[PATCH v9] audio/pwaudio.c: Add Pipewire audio backend for QEMU

Dorinda Bassey posted 1 patch 1 year, 1 month ago
Patches applied successfully (tree, apply log)
git fetch https://github.com/patchew-project/qemu tags/patchew/20230328130819.136186-1-dbassey@redhat.com
Maintainers: Gerd Hoffmann <kraxel@redhat.com>, "Marc-André Lureau" <marcandre.lureau@redhat.com>, Paolo Bonzini <pbonzini@redhat.com>, "Daniel P. Berrangé" <berrange@redhat.com>, Thomas Huth <thuth@redhat.com>, "Philippe Mathieu-Daudé" <philmd@linaro.org>, Eric Blake <eblake@redhat.com>, Markus Armbruster <armbru@redhat.com>
There is a newer version of this series
audio/audio.c                 |   3 +
audio/audio_template.h        |   4 +
audio/meson.build             |   1 +
audio/pwaudio.c               | 879 ++++++++++++++++++++++++++++++++++
audio/trace-events            |   8 +
meson.build                   |   8 +
meson_options.txt             |   4 +-
qapi/audio.json               |  44 ++
qemu-options.hx               |  21 +
scripts/meson-buildoptions.sh |   8 +-
10 files changed, 977 insertions(+), 3 deletions(-)
create mode 100644 audio/pwaudio.c
[PATCH v9] audio/pwaudio.c: Add Pipewire audio backend for QEMU
Posted by Dorinda Bassey 1 year, 1 month ago
This commit adds a new audiodev backend to allow QEMU to use Pipewire as
both an audio sink and source. This backend is available on most systems

Add Pipewire entry points for QEMU Pipewire audio backend
Add wrappers for QEMU Pipewire audio backend in qpw_pcm_ops()
qpw_write function returns the current state of the stream to pwaudio
and Writes some data to the server for playback streams using pipewire
spa_ringbuffer implementation.
qpw_read function returns the current state of the stream to pwaudio and
reads some data from the server for capture streams using pipewire
spa_ringbuffer implementation. These functions qpw_write and qpw_read
are called during playback and capture.
Added some functions that convert pw audio formats to QEMU audio format
and vice versa which would be needed in the pipewire audio sink and
source functions qpw_init_in() & qpw_init_out().
These methods that implement playback and recording will create streams
for playback and capture that will start processing and will result in
the on_process callbacks to be called.
Built a connection to the Pipewire sound system server in the
qpw_audio_init() method.

Signed-off-by: Dorinda Bassey <dbassey@redhat.com>
---
v9:
add code to play silence on a buffer underrun
remove redundant block in playback and capture process functions
refactor code for enabling/disabling audio stream
add volume_out and volume_in pcm_ops function
add code for in|out.name options
add in|out.stream-name options
fix format specifiers
change release version
add missing latency option

 audio/audio.c                 |   3 +
 audio/audio_template.h        |   4 +
 audio/meson.build             |   1 +
 audio/pwaudio.c               | 879 ++++++++++++++++++++++++++++++++++
 audio/trace-events            |   8 +
 meson.build                   |   8 +
 meson_options.txt             |   4 +-
 qapi/audio.json               |  44 ++
 qemu-options.hx               |  21 +
 scripts/meson-buildoptions.sh |   8 +-
 10 files changed, 977 insertions(+), 3 deletions(-)
 create mode 100644 audio/pwaudio.c

diff --git a/audio/audio.c b/audio/audio.c
index 70b096713c..90c7c49d11 100644
--- a/audio/audio.c
+++ b/audio/audio.c
@@ -2061,6 +2061,9 @@ void audio_create_pdos(Audiodev *dev)
 #ifdef CONFIG_AUDIO_PA
         CASE(PA, pa, Pa);
 #endif
+#ifdef CONFIG_AUDIO_PIPEWIRE
+        CASE(PIPEWIRE, pipewire, Pipewire);
+#endif
 #ifdef CONFIG_AUDIO_SDL
         CASE(SDL, sdl, Sdl);
 #endif
diff --git a/audio/audio_template.h b/audio/audio_template.h
index e42326c20d..dc0c74aa74 100644
--- a/audio/audio_template.h
+++ b/audio/audio_template.h
@@ -362,6 +362,10 @@ AudiodevPerDirectionOptions *glue(audio_get_pdo_, TYPE)(Audiodev *dev)
     case AUDIODEV_DRIVER_PA:
         return qapi_AudiodevPaPerDirectionOptions_base(dev->u.pa.TYPE);
 #endif
+#ifdef CONFIG_AUDIO_PIPEWIRE
+    case AUDIODEV_DRIVER_PIPEWIRE:
+        return qapi_AudiodevPipewirePerDirectionOptions_base(dev->u.pipewire.TYPE);
+#endif
 #ifdef CONFIG_AUDIO_SDL
     case AUDIODEV_DRIVER_SDL:
         return qapi_AudiodevSdlPerDirectionOptions_base(dev->u.sdl.TYPE);
diff --git a/audio/meson.build b/audio/meson.build
index 0722224ba9..65a49c1a10 100644
--- a/audio/meson.build
+++ b/audio/meson.build
@@ -19,6 +19,7 @@ foreach m : [
   ['sdl', sdl, files('sdlaudio.c')],
   ['jack', jack, files('jackaudio.c')],
   ['sndio', sndio, files('sndioaudio.c')],
+  ['pipewire', pipewire, files('pwaudio.c')],
   ['spice', spice, files('spiceaudio.c')]
 ]
   if m[1].found()
diff --git a/audio/pwaudio.c b/audio/pwaudio.c
new file mode 100644
index 0000000000..ca83bc55f9
--- /dev/null
+++ b/audio/pwaudio.c
@@ -0,0 +1,879 @@
+/*
+ * QEMU Pipewire audio driver
+ *
+ * Copyright (c) 2023 Red Hat Inc.
+ *
+ * Author: Dorinda Bassey       <dbassey@redhat.com>
+ *
+ * SPDX-License-Identifier: GPL-2.0-or-later
+ */
+
+#include "qemu/osdep.h"
+#include "qemu/module.h"
+#include "audio.h"
+#include <errno.h>
+#include "qemu/error-report.h"
+#include <spa/param/audio/format-utils.h>
+#include <spa/utils/ringbuffer.h>
+#include <spa/utils/result.h>
+#include <spa/param/props.h>
+
+#include <pipewire/pipewire.h>
+#include "trace.h"
+
+#define AUDIO_CAP "pipewire"
+#define RINGBUFFER_SIZE    (1u << 22)
+#define RINGBUFFER_MASK    (RINGBUFFER_SIZE - 1)
+
+#include "audio_int.h"
+
+enum {
+    MODE_SINK,
+    MODE_SOURCE
+};
+
+typedef struct pwvolume {
+    uint32_t channels;
+    float values[SPA_AUDIO_MAX_CHANNELS];
+} pwvolume;
+
+typedef struct pwaudio {
+    Audiodev *dev;
+    struct pw_thread_loop *thread_loop;
+    struct pw_context *context;
+
+    struct pw_core *core;
+    struct spa_hook core_listener;
+    int seq;
+} pwaudio;
+
+typedef struct PWVoice {
+    pwaudio *g;
+    struct pw_stream *stream;
+    struct spa_hook stream_listener;
+    struct spa_audio_info_raw info;
+    uint32_t highwater_mark;
+    uint32_t frame_size;
+    struct spa_ringbuffer ring;
+    uint8_t buffer[RINGBUFFER_SIZE];
+
+    uint32_t mode;
+    struct pw_properties *props;
+    pwvolume volume;
+    bool muted;
+} PWVoice;
+
+typedef struct PWVoiceOut {
+    HWVoiceOut hw;
+    PWVoice v;
+} PWVoiceOut;
+
+typedef struct PWVoiceIn {
+    HWVoiceIn hw;
+    PWVoice v;
+} PWVoiceIn;
+
+static void
+stream_destroy(void *data)
+{
+    PWVoice *v = (PWVoice *) data;
+    spa_hook_remove(&v->stream_listener);
+    v->stream = NULL;
+}
+
+/* output data processing function to read stuffs from the buffer */
+static void
+playback_on_process(void *data)
+{
+    PWVoice *v = (PWVoice *) data;
+    void *p;
+    struct pw_buffer *b;
+    struct spa_buffer *buf;
+    uint32_t req, index, n_bytes;
+    int32_t avail;
+
+    if (!v->stream) {
+        return;
+    }
+
+    /* obtain a buffer to read from */
+    b = pw_stream_dequeue_buffer(v->stream);
+    if (b == NULL) {
+        error_report("out of buffers: %s", strerror(errno));
+        return;
+    }
+
+    buf = b->buffer;
+    p = buf->datas[0].data;
+    if (p == NULL) {
+        return;
+    }
+    /* calculate the total no of bytes to read data from buffer */
+    req = b->requested * v->frame_size;
+    if (req == 0) {
+        req = (uint64_t)v->g->dev->timer_period * v->info.rate
+                * 1 / 2 / 1000000 * v->frame_size;
+    }
+    n_bytes = SPA_MIN(req, buf->datas[0].maxsize);
+
+    /* get no of available bytes to read data from buffer */
+
+    avail = spa_ringbuffer_get_read_index(&v->ring, &index);
+
+
+    if (avail == 0) {
+        memset(p, 0, n_bytes);
+    }
+
+    if (avail < (int32_t) n_bytes) {
+        n_bytes = avail;
+    }
+
+    spa_ringbuffer_read_data(&v->ring,
+                                v->buffer, RINGBUFFER_SIZE,
+                                index & RINGBUFFER_MASK, p, n_bytes);
+
+    index += n_bytes;
+    spa_ringbuffer_read_update(&v->ring, index);
+
+    buf->datas[0].chunk->offset = 0;
+    buf->datas[0].chunk->stride = v->frame_size;
+    buf->datas[0].chunk->size = n_bytes;
+
+    /* queue the buffer for playback */
+    pw_stream_queue_buffer(v->stream, b);
+}
+
+/* output data processing function to generate stuffs in the buffer */
+static void
+capture_on_process(void *data)
+{
+    PWVoice *v = (PWVoice *) data;
+    void *p;
+    struct pw_buffer *b;
+    struct spa_buffer *buf;
+    int32_t filled;
+    uint32_t index, offs, n_bytes;
+
+    if (!v->stream) {
+        return;
+    }
+
+    /* obtain a buffer */
+    b = pw_stream_dequeue_buffer(v->stream);
+    if (b == NULL) {
+        error_report("out of buffers: %s", strerror(errno));
+        return;
+    }
+
+    /* Write data into buffer */
+    buf = b->buffer;
+    p = buf->datas[0].data;
+    if (p == NULL) {
+        return;
+    }
+    offs = SPA_MIN(buf->datas[0].chunk->offset, buf->datas[0].maxsize);
+    n_bytes = SPA_MIN(buf->datas[0].chunk->size, buf->datas[0].maxsize - offs);
+
+    filled = spa_ringbuffer_get_write_index(&v->ring, &index);
+
+
+    if (filled < 0) {
+        error_report("%p: underrun write:%u filled:%d", p, index, filled);
+    } else {
+        if ((uint32_t) filled + n_bytes > RINGBUFFER_SIZE) {
+            error_report("%p: overrun write:%u filled:%d + size:%u > max:%u",
+            p, index, filled, n_bytes, RINGBUFFER_SIZE);
+        }
+    }
+    spa_ringbuffer_write_data(&v->ring,
+                                v->buffer, RINGBUFFER_SIZE,
+                                index & RINGBUFFER_MASK,
+                                SPA_PTROFF(p, offs, void), n_bytes);
+    index += n_bytes;
+    spa_ringbuffer_write_update(&v->ring, index);
+
+    /* queue the buffer for playback */
+    pw_stream_queue_buffer(v->stream, b);
+}
+
+static void
+on_stream_state_changed(void *_data, enum pw_stream_state old,
+                        enum pw_stream_state state, const char *error)
+{
+    PWVoice *v = (PWVoice *) _data;
+
+    trace_pw_state_changed(pw_stream_state_as_string(state));
+
+    switch (state) {
+    case PW_STREAM_STATE_ERROR:
+    case PW_STREAM_STATE_UNCONNECTED:
+        {
+            break;
+        }
+    case PW_STREAM_STATE_PAUSED:
+        trace_pw_node(pw_stream_get_node_id(v->stream));
+        break;
+    case PW_STREAM_STATE_CONNECTING:
+    case PW_STREAM_STATE_STREAMING:
+        break;
+    }
+}
+
+static const struct pw_stream_events capture_stream_events = {
+    PW_VERSION_STREAM_EVENTS,
+    .destroy = stream_destroy,
+    .state_changed = on_stream_state_changed,
+    .process = capture_on_process
+};
+
+static const struct pw_stream_events playback_stream_events = {
+    PW_VERSION_STREAM_EVENTS,
+    .destroy = stream_destroy,
+    .state_changed = on_stream_state_changed,
+    .process = playback_on_process
+};
+
+static size_t
+qpw_read(HWVoiceIn *hw, void *data, size_t len)
+{
+    PWVoiceIn *pw = (PWVoiceIn *) hw;
+    PWVoice *v = &pw->v;
+    pwaudio *c = v->g;
+    const char *error = NULL;
+    size_t l;
+    int32_t avail;
+    uint32_t index;
+
+    pw_thread_loop_lock(c->thread_loop);
+    if (pw_stream_get_state(v->stream, &error) != PW_STREAM_STATE_STREAMING) {
+        /* wait for stream to become ready */
+        l = 0;
+        goto done_unlock;
+    }
+    /* get no of available bytes to read data from buffer */
+    avail = spa_ringbuffer_get_read_index(&v->ring, &index);
+
+    trace_pw_read(avail, index, len);
+
+    if (avail < (int32_t) len) {
+        len = avail;
+    }
+
+    spa_ringbuffer_read_data(&v->ring,
+                             v->buffer, RINGBUFFER_SIZE,
+                             index & RINGBUFFER_MASK, data, len);
+    index += len;
+    spa_ringbuffer_read_update(&v->ring, index);
+    l = len;
+
+done_unlock:
+    pw_thread_loop_unlock(c->thread_loop);
+    return l;
+}
+
+static size_t qpw_buffer_get_free(HWVoiceOut *hw)
+{
+    PWVoiceOut *pw = (PWVoiceOut *)hw;
+    PWVoice *v = &pw->v;
+    pwaudio *c = v->g;
+    const char *error = NULL;
+    int32_t filled, avail;
+    uint32_t index;
+
+    pw_thread_loop_lock(c->thread_loop);
+    if (pw_stream_get_state(v->stream, &error) != PW_STREAM_STATE_STREAMING) {
+        /* wait for stream to become ready */
+        avail = 0;
+        goto done_unlock;
+    }
+
+    filled = spa_ringbuffer_get_write_index(&v->ring, &index);
+    avail = v->highwater_mark - filled;
+
+done_unlock:
+    pw_thread_loop_unlock(c->thread_loop);
+    return avail;
+}
+
+static size_t
+qpw_write(HWVoiceOut *hw, void *data, size_t len)
+{
+    PWVoiceOut *pw = (PWVoiceOut *) hw;
+    PWVoice *v = &pw->v;
+    pwaudio *c = v->g;
+    const char *error = NULL;
+    int32_t filled, avail;
+    uint32_t index;
+
+    pw_thread_loop_lock(c->thread_loop);
+    if (pw_stream_get_state(v->stream, &error) != PW_STREAM_STATE_STREAMING) {
+        /* wait for stream to become ready */
+        len = 0;
+        goto done_unlock;
+    }
+    filled = spa_ringbuffer_get_write_index(&v->ring, &index);
+    avail = v->highwater_mark - filled;
+
+    trace_pw_write(filled, avail, index, len);
+
+    if (len > avail) {
+        len = avail;
+    }
+
+    if (filled < 0) {
+        error_report("%p: underrun write:%u filled:%d", pw, index, filled);
+    } else {
+        if ((uint32_t) filled + len > RINGBUFFER_SIZE) {
+            error_report("%p: overrun write:%u filled:%d + size:%zu > max:%u",
+            pw, index, filled, len, RINGBUFFER_SIZE);
+        }
+    }
+
+    spa_ringbuffer_write_data(&v->ring,
+                                v->buffer, RINGBUFFER_SIZE,
+                                index & RINGBUFFER_MASK, data, len);
+    index += len;
+    spa_ringbuffer_write_update(&v->ring, index);
+
+done_unlock:
+    pw_thread_loop_unlock(c->thread_loop);
+    return len;
+}
+
+static int
+audfmt_to_pw(AudioFormat fmt, int endianness)
+{
+    int format;
+
+    switch (fmt) {
+    case AUDIO_FORMAT_S8:
+        format = SPA_AUDIO_FORMAT_S8;
+        break;
+    case AUDIO_FORMAT_U8:
+        format = SPA_AUDIO_FORMAT_U8;
+        break;
+    case AUDIO_FORMAT_S16:
+        format = endianness ? SPA_AUDIO_FORMAT_S16_BE : SPA_AUDIO_FORMAT_S16_LE;
+        break;
+    case AUDIO_FORMAT_U16:
+        format = endianness ? SPA_AUDIO_FORMAT_U16_BE : SPA_AUDIO_FORMAT_U16_LE;
+        break;
+    case AUDIO_FORMAT_S32:
+        format = endianness ? SPA_AUDIO_FORMAT_S32_BE : SPA_AUDIO_FORMAT_S32_LE;
+        break;
+    case AUDIO_FORMAT_U32:
+        format = endianness ? SPA_AUDIO_FORMAT_U32_BE : SPA_AUDIO_FORMAT_U32_LE;
+        break;
+    case AUDIO_FORMAT_F32:
+        format = endianness ? SPA_AUDIO_FORMAT_F32_BE : SPA_AUDIO_FORMAT_F32_LE;
+        break;
+    default:
+        dolog("Internal logic error: Bad audio format %d\n", fmt);
+        format = SPA_AUDIO_FORMAT_U8;
+        break;
+    }
+    return format;
+}
+
+static AudioFormat
+pw_to_audfmt(enum spa_audio_format fmt, int *endianness,
+             uint32_t *frame_size)
+{
+    switch (fmt) {
+    case SPA_AUDIO_FORMAT_S8:
+        *frame_size = 1;
+        return AUDIO_FORMAT_S8;
+    case SPA_AUDIO_FORMAT_U8:
+        *frame_size = 1;
+        return AUDIO_FORMAT_U8;
+    case SPA_AUDIO_FORMAT_S16_BE:
+        *frame_size = 2;
+        *endianness = 1;
+        return AUDIO_FORMAT_S16;
+    case SPA_AUDIO_FORMAT_S16_LE:
+        *frame_size = 2;
+        *endianness = 0;
+        return AUDIO_FORMAT_S16;
+    case SPA_AUDIO_FORMAT_U16_BE:
+        *frame_size = 2;
+        *endianness = 1;
+        return AUDIO_FORMAT_U16;
+    case SPA_AUDIO_FORMAT_U16_LE:
+        *frame_size = 2;
+        *endianness = 0;
+        return AUDIO_FORMAT_U16;
+    case SPA_AUDIO_FORMAT_S32_BE:
+        *frame_size = 4;
+        *endianness = 1;
+        return AUDIO_FORMAT_S32;
+    case SPA_AUDIO_FORMAT_S32_LE:
+        *frame_size = 4;
+        *endianness = 0;
+        return AUDIO_FORMAT_S32;
+    case SPA_AUDIO_FORMAT_U32_BE:
+        *frame_size = 4;
+        *endianness = 1;
+        return AUDIO_FORMAT_U32;
+    case SPA_AUDIO_FORMAT_U32_LE:
+        *frame_size = 4;
+        *endianness = 0;
+        return AUDIO_FORMAT_U32;
+    case SPA_AUDIO_FORMAT_F32_BE:
+        *frame_size = 4;
+        *endianness = 1;
+        return AUDIO_FORMAT_F32;
+    case SPA_AUDIO_FORMAT_F32_LE:
+        *frame_size = 4;
+        *endianness = 0;
+        return AUDIO_FORMAT_F32;
+    default:
+        *frame_size = 1;
+        dolog("Internal logic error: Bad spa_audio_format %d\n", fmt);
+        return AUDIO_FORMAT_U8;
+    }
+}
+
+static int
+create_stream(pwaudio *c, PWVoice *v, const char *stream_name, const char *name)
+{
+    int res;
+    uint32_t n_params;
+    const struct spa_pod *params[2];
+    uint8_t buffer[1024];
+    struct spa_pod_builder b;
+
+    v->props = pw_properties_new(NULL, NULL);
+    pw_properties_setf(v->props, PW_KEY_NODE_LATENCY, "%" PRIu64 "/%u",
+                       (uint64_t)v->g->dev->timer_period * v->info.rate
+                       * 3 / 4 / 1000000, v->info.rate);
+    if (name) {
+        pw_properties_set(v->props, PW_KEY_TARGET_OBJECT, name);
+    }
+    v->stream = pw_stream_new(c->core, stream_name, v->props);
+
+    if (v->stream == NULL) {
+        return -1;
+    }
+
+    if (v->mode == MODE_SOURCE) {
+        pw_stream_add_listener(v->stream,
+                            &v->stream_listener, &capture_stream_events, v);
+    } else {
+        pw_stream_add_listener(v->stream,
+                            &v->stream_listener, &playback_stream_events, v);
+    }
+
+    n_params = 0;
+    spa_pod_builder_init(&b, buffer, sizeof(buffer));
+    params[n_params++] = spa_format_audio_raw_build(&b,
+                            SPA_PARAM_EnumFormat,
+                            &v->info);
+
+    /* connect the stream to a sink or source */
+    res = pw_stream_connect(v->stream,
+                            v->mode ==
+                            MODE_SOURCE ? PW_DIRECTION_INPUT :
+                            PW_DIRECTION_OUTPUT, PW_ID_ANY,
+                            PW_STREAM_FLAG_AUTOCONNECT |
+                            PW_STREAM_FLAG_INACTIVE |
+                            PW_STREAM_FLAG_MAP_BUFFERS |
+                            PW_STREAM_FLAG_RT_PROCESS, params, n_params);
+    if (res < 0) {
+        pw_stream_destroy(v->stream);
+        return -1;
+    }
+
+    return 0;
+}
+
+static int
+qpw_stream_new(pwaudio *c, PWVoice *v,
+               const char *stream_name, const char *name)
+{
+    int r;
+
+    switch (v->info.channels) {
+    case 8:
+        v->info.position[0] = SPA_AUDIO_CHANNEL_FL;
+        v->info.position[1] = SPA_AUDIO_CHANNEL_FR;
+        v->info.position[2] = SPA_AUDIO_CHANNEL_FC;
+        v->info.position[3] = SPA_AUDIO_CHANNEL_LFE;
+        v->info.position[4] = SPA_AUDIO_CHANNEL_RL;
+        v->info.position[5] = SPA_AUDIO_CHANNEL_RR;
+        v->info.position[6] = SPA_AUDIO_CHANNEL_SL;
+        v->info.position[7] = SPA_AUDIO_CHANNEL_SR;
+        break;
+    case 6:
+        v->info.position[0] = SPA_AUDIO_CHANNEL_FL;
+        v->info.position[1] = SPA_AUDIO_CHANNEL_FR;
+        v->info.position[2] = SPA_AUDIO_CHANNEL_FC;
+        v->info.position[3] = SPA_AUDIO_CHANNEL_LFE;
+        v->info.position[4] = SPA_AUDIO_CHANNEL_RL;
+        v->info.position[5] = SPA_AUDIO_CHANNEL_RR;
+        break;
+    case 5:
+        v->info.position[0] = SPA_AUDIO_CHANNEL_FL;
+        v->info.position[1] = SPA_AUDIO_CHANNEL_FR;
+        v->info.position[2] = SPA_AUDIO_CHANNEL_FC;
+        v->info.position[3] = SPA_AUDIO_CHANNEL_LFE;
+        v->info.position[4] = SPA_AUDIO_CHANNEL_RC;
+        break;
+    case 4:
+        v->info.position[0] = SPA_AUDIO_CHANNEL_FL;
+        v->info.position[1] = SPA_AUDIO_CHANNEL_FR;
+        v->info.position[2] = SPA_AUDIO_CHANNEL_FC;
+        v->info.position[3] = SPA_AUDIO_CHANNEL_RC;
+        break;
+    case 3:
+        v->info.position[0] = SPA_AUDIO_CHANNEL_FL;
+        v->info.position[1] = SPA_AUDIO_CHANNEL_FR;
+        v->info.position[2] = SPA_AUDIO_CHANNEL_LFE;
+        break;
+    case 2:
+        v->info.position[0] = SPA_AUDIO_CHANNEL_FL;
+        v->info.position[1] = SPA_AUDIO_CHANNEL_FR;
+        break;
+    case 1:
+        v->info.position[0] = SPA_AUDIO_CHANNEL_MONO;
+        break;
+    default:
+        for (size_t i = 0; i < v->info.channels; i++) {
+            v->info.position[i] = SPA_AUDIO_CHANNEL_UNKNOWN;
+        }
+        break;
+    }
+
+    /* create a new unconnected pwstream */
+    r = create_stream(c, v, stream_name, name);
+    if (r < 0) {
+        AUD_log(AUDIO_CAP, "Failed to create stream.");
+        return -1;
+    }
+
+    return r;
+}
+
+static int
+qpw_init_out(HWVoiceOut *hw, struct audsettings *as, void *drv_opaque)
+{
+    PWVoiceOut *pw = (PWVoiceOut *) hw;
+    PWVoice *v = &pw->v;
+    struct audsettings obt_as = *as;
+    pwaudio *c = v->g = drv_opaque;
+    AudiodevPipewireOptions *popts = &c->dev->u.pipewire;
+    AudiodevPipewirePerDirectionOptions *ppdo = popts->out;
+    int r;
+
+    v->mode = MODE_SINK;
+
+    pw_thread_loop_lock(c->thread_loop);
+
+    v->info.format = audfmt_to_pw(as->fmt, as->endianness);
+    v->info.channels = as->nchannels;
+    v->info.rate = as->freq;
+
+    obt_as.fmt =
+        pw_to_audfmt(v->info.format, &obt_as.endianness, &v->frame_size);
+    v->frame_size *= as->nchannels;
+
+    /* call the function that creates a new stream for playback */
+    r = qpw_stream_new(c, v, ppdo->stream_name ? : c->dev->id, ppdo->name);
+    if (r < 0) {
+        error_report("qpw_stream_new for playback failed");
+        pw_thread_loop_unlock(c->thread_loop);
+        return -1;
+    }
+
+    /* report the audio format we support */
+    audio_pcm_init_info(&hw->info, &obt_as);
+
+    /* report the buffer size to qemu */
+    hw->samples = audio_buffer_frames(
+        qapi_AudiodevPipewirePerDirectionOptions_base(ppdo), &obt_as, 46440);
+    v->highwater_mark = MIN(RINGBUFFER_SIZE,
+                            (ppdo->has_latency ? ppdo->latency : 46440)
+                            * (uint64_t)v->info.rate / 1000000 * v->frame_size);
+
+    pw_thread_loop_unlock(c->thread_loop);
+    return 0;
+}
+
+static int
+qpw_init_in(HWVoiceIn *hw, struct audsettings *as, void *drv_opaque)
+{
+    PWVoiceIn *pw = (PWVoiceIn *) hw;
+    PWVoice *v = &pw->v;
+    struct audsettings obt_as = *as;
+    pwaudio *c = v->g = drv_opaque;
+    AudiodevPipewireOptions *popts = &c->dev->u.pipewire;
+    AudiodevPipewirePerDirectionOptions *ppdo = popts->in;
+    int r;
+
+    v->mode = MODE_SOURCE;
+    pw_thread_loop_lock(c->thread_loop);
+
+    v->info.format = audfmt_to_pw(as->fmt, as->endianness);
+    v->info.channels = as->nchannels;
+    v->info.rate = as->freq;
+
+    obt_as.fmt =
+        pw_to_audfmt(v->info.format, &obt_as.endianness, &v->frame_size);
+    v->frame_size *= as->nchannels;
+
+    /* call the function that creates a new stream for recording */
+    r = qpw_stream_new(c, v, ppdo->stream_name ? : c->dev->id, ppdo->name);
+    if (r < 0) {
+        error_report("qpw_stream_new for recording failed");
+        pw_thread_loop_unlock(c->thread_loop);
+        return -1;
+    }
+
+    /* report the audio format we support */
+    audio_pcm_init_info(&hw->info, &obt_as);
+
+    /* report the buffer size to qemu */
+    hw->samples = audio_buffer_frames(
+        qapi_AudiodevPipewirePerDirectionOptions_base(ppdo), &obt_as, 46440);
+
+    pw_thread_loop_unlock(c->thread_loop);
+    return 0;
+}
+
+static void
+qpw_fini_out(HWVoiceOut *hw)
+{
+    PWVoiceOut *pw = (PWVoiceOut *) hw;
+    PWVoice *v = &pw->v;
+
+    if (v->stream) {
+        pwaudio *c = v->g;
+        pw_thread_loop_lock(c->thread_loop);
+        pw_stream_destroy(v->stream);
+        v->stream = NULL;
+        pw_thread_loop_unlock(c->thread_loop);
+    }
+}
+
+static void
+qpw_fini_in(HWVoiceIn *hw)
+{
+    PWVoiceIn *pw = (PWVoiceIn *) hw;
+    PWVoice *v = &pw->v;
+
+    if (v->stream) {
+        pwaudio *c = v->g;
+        pw_thread_loop_lock(c->thread_loop);
+        pw_stream_destroy(v->stream);
+        v->stream = NULL;
+        pw_thread_loop_unlock(c->thread_loop);
+    }
+}
+
+static void
+qpw_enable_out(HWVoiceOut *hw, bool enable)
+{
+    PWVoiceOut *po = (PWVoiceOut *) hw;
+    PWVoice *v = &po->v;
+    pw_stream_set_active(v->stream, enable);
+}
+
+static void
+qpw_enable_in(HWVoiceIn *hw, bool enable)
+{
+    PWVoiceIn *pi = (PWVoiceIn *) hw;
+    PWVoice *v = &pi->v;
+    pw_stream_set_active(v->stream, enable);
+}
+
+static void
+qpw_volume_out(HWVoiceOut *hw, Volume *vol)
+{
+    PWVoiceOut *pw = (PWVoiceOut *) hw;
+    PWVoice *v = &pw->v;
+    pwaudio *c = v->g;
+    int i, ret;
+
+    pw_thread_loop_lock(c->thread_loop);
+    v->volume.channels = vol->channels;
+
+    for (i = 0; i < vol->channels; ++i) {
+        v->volume.values[i] = vol->vol[i] / 100;
+    }
+
+    ret = pw_stream_set_control(v->stream,
+        SPA_PROP_channelVolumes, v->volume.channels, v->volume.values, 0);
+    trace_pw_vol(ret == 0 ? "success" : "failed");
+
+    v->muted = vol->mute;
+    float val = v->muted ? 1.f : 0.f;
+    ret = pw_stream_set_control(v->stream, SPA_PROP_mute, 1, &val, 0);
+    pw_thread_loop_unlock(c->thread_loop);
+}
+
+static void
+qpw_volume_in(HWVoiceIn *hw, Volume *vol)
+{
+    PWVoiceIn *pw = (PWVoiceIn *) hw;
+    PWVoice *v = &pw->v;
+    pwaudio *c = v->g;
+    int i, ret;
+
+    pw_thread_loop_lock(c->thread_loop);
+    v->volume.channels = vol->channels;
+
+    for (i = 0; i < vol->channels; ++i) {
+        v->volume.values[i] = vol->vol[i] / 100;
+    }
+
+    ret = pw_stream_set_control(v->stream,
+        SPA_PROP_channelVolumes, v->volume.channels, v->volume.values, 0);
+    trace_pw_vol(ret == 0 ? "success" : "failed");
+
+    v->muted = vol->mute;
+    float val = v->muted ? 1.f : 0.f;
+    ret = pw_stream_set_control(v->stream, SPA_PROP_mute, 1, &val, 0);
+    pw_thread_loop_unlock(c->thread_loop);
+}
+
+static void
+on_core_error(void *data, uint32_t id, int seq, int res, const char *message)
+{
+    pwaudio *pw = data;
+
+    error_report("error id:%u seq:%d res:%d (%s): %s",
+                id, seq, res, spa_strerror(res), message);
+
+    /* stop and exit the thread loop */
+    pw_thread_loop_signal(pw->thread_loop, FALSE);
+}
+
+static void
+on_core_done(void *data, uint32_t id, int seq)
+{
+    pwaudio *pw = data;
+    if (id == PW_ID_CORE) {
+        pw->seq = seq;
+        /* stop and exit the thread loop */
+        pw_thread_loop_signal(pw->thread_loop, FALSE);
+    }
+}
+
+static const struct pw_core_events core_events = {
+    PW_VERSION_CORE_EVENTS,
+    .done = on_core_done,
+    .error = on_core_error,
+};
+
+static void *
+qpw_audio_init(Audiodev *dev)
+{
+    g_autofree pwaudio *pw = g_new0(pwaudio, 1);
+    pw_init(NULL, NULL);
+
+    trace_pw_audio_init();
+    assert(dev->driver == AUDIODEV_DRIVER_PIPEWIRE);
+
+    pw->dev = dev;
+    pw->thread_loop = pw_thread_loop_new("Pipewire thread loop", NULL);
+    if (pw->thread_loop == NULL) {
+        error_report("Could not create Pipewire loop");
+        goto fail;
+    }
+
+    pw->context =
+        pw_context_new(pw_thread_loop_get_loop(pw->thread_loop), NULL, 0);
+    if (pw->context == NULL) {
+        error_report("Could not create Pipewire context");
+        goto fail;
+    }
+
+    if (pw_thread_loop_start(pw->thread_loop) < 0) {
+        error_report("Could not start Pipewire loop");
+        goto fail;
+    }
+
+    pw_thread_loop_lock(pw->thread_loop);
+
+    pw->core = pw_context_connect(pw->context, NULL, 0);
+    if (pw->core == NULL) {
+        pw_thread_loop_unlock(pw->thread_loop);
+        goto fail;
+    }
+
+    pw_core_add_listener(pw->core, &pw->core_listener, &core_events, pw);
+
+    pw_thread_loop_unlock(pw->thread_loop);
+
+    return g_steal_pointer(&pw);
+
+fail:
+    AUD_log(AUDIO_CAP, "Failed to initialize PW context");
+    if (pw->thread_loop) {
+        pw_thread_loop_stop(pw->thread_loop);
+        g_clear_pointer(&pw->thread_loop, pw_thread_loop_destroy);
+    }
+    if (pw->context) {
+        g_clear_pointer(&pw->context, pw_context_destroy);
+    }
+    return NULL;
+}
+
+static void
+qpw_audio_fini(void *opaque)
+{
+    pwaudio *pw = opaque;
+
+    pw_thread_loop_stop(pw->thread_loop);
+
+    if (pw->core) {
+        spa_hook_remove(&pw->core_listener);
+        spa_zero(pw->core_listener);
+        pw_core_disconnect(pw->core);
+    }
+
+    if (pw->context) {
+        pw_context_destroy(pw->context);
+    }
+    pw_thread_loop_destroy(pw->thread_loop);
+
+    g_free(pw);
+}
+
+static struct audio_pcm_ops qpw_pcm_ops = {
+    .init_out = qpw_init_out,
+    .fini_out = qpw_fini_out,
+    .write = qpw_write,
+    .buffer_get_free = qpw_buffer_get_free,
+    .run_buffer_out = audio_generic_run_buffer_out,
+    .enable_out = qpw_enable_out,
+    .volume_out = qpw_volume_out,
+    .volume_in = qpw_volume_in,
+
+    .init_in = qpw_init_in,
+    .fini_in = qpw_fini_in,
+    .read = qpw_read,
+    .run_buffer_in = audio_generic_run_buffer_in,
+    .enable_in = qpw_enable_in
+};
+
+static struct audio_driver pw_audio_driver = {
+    .name = "pipewire",
+    .descr = "http://www.pipewire.org/",
+    .init = qpw_audio_init,
+    .fini = qpw_audio_fini,
+    .pcm_ops = &qpw_pcm_ops,
+    .can_be_default = 1,
+    .max_voices_out = INT_MAX,
+    .max_voices_in = INT_MAX,
+    .voice_size_out = sizeof(PWVoiceOut),
+    .voice_size_in = sizeof(PWVoiceIn),
+};
+
+static void
+register_audio_pw(void)
+{
+    audio_driver_register(&pw_audio_driver);
+}
+
+type_init(register_audio_pw);
diff --git a/audio/trace-events b/audio/trace-events
index e1ab643add..59ec817c9d 100644
--- a/audio/trace-events
+++ b/audio/trace-events
@@ -18,6 +18,14 @@ dbus_audio_register(const char *s, const char *dir) "sender = %s, dir = %s"
 dbus_audio_put_buffer_out(size_t len) "len = %zu"
 dbus_audio_read(size_t len) "len = %zu"
 
+# pwaudio.c
+pw_state_changed(const char *s) "stream state: %s"
+pw_node(int nodeid) "node id: %d"
+pw_read(int32_t avail, uint32_t index, size_t len) "avail=%d index=%u len=%zu"
+pw_write(int32_t filled, int32_t avail, uint32_t index, size_t len) "filled=%d avail=%d index=%u len=%zu"
+pw_vol(const char *ret) "set volume: %s"
+pw_audio_init(void) "Initialize Pipewire context"
+
 # audio.c
 audio_timer_start(int interval) "interval %d ms"
 audio_timer_stop(void) ""
diff --git a/meson.build b/meson.build
index 29f8644d6d..31bf280c0d 100644
--- a/meson.build
+++ b/meson.build
@@ -730,6 +730,12 @@ if not get_option('jack').auto() or have_system
   jack = dependency('jack', required: get_option('jack'),
                     method: 'pkg-config', kwargs: static_kwargs)
 endif
+pipewire = not_found
+if not get_option('pipewire').auto() or (targetos == 'linux' and have_system)
+  pipewire = dependency('libpipewire-0.3', version: '>=0.3.60',
+                    required: get_option('pipewire'),
+                    method: 'pkg-config', kwargs: static_kwargs)
+endif
 sndio = not_found
 if not get_option('sndio').auto() or have_system
   sndio = dependency('sndio', required: get_option('sndio'),
@@ -1667,6 +1673,7 @@ if have_system
     'jack': jack.found(),
     'oss': oss.found(),
     'pa': pulse.found(),
+    'pipewire': pipewire.found(),
     'sdl': sdl.found(),
     'sndio': sndio.found(),
   }
@@ -3980,6 +3987,7 @@ if targetos == 'linux'
   summary_info += {'ALSA support':    alsa}
   summary_info += {'PulseAudio support': pulse}
 endif
+summary_info += {'Pipewire support':   pipewire}
 summary_info += {'JACK support':      jack}
 summary_info += {'brlapi support':    brlapi}
 summary_info += {'vde support':       vde}
diff --git a/meson_options.txt b/meson_options.txt
index fc9447d267..9ae1ec7f47 100644
--- a/meson_options.txt
+++ b/meson_options.txt
@@ -21,7 +21,7 @@ option('tls_priority', type : 'string', value : 'NORMAL',
 option('default_devices', type : 'boolean', value : true,
        description: 'Include a default selection of devices in emulators')
 option('audio_drv_list', type: 'array', value: ['default'],
-       choices: ['alsa', 'coreaudio', 'default', 'dsound', 'jack', 'oss', 'pa', 'sdl', 'sndio'],
+       choices: ['alsa', 'coreaudio', 'default', 'dsound', 'jack', 'oss', 'pa', 'pipewire', 'sdl', 'sndio'],
        description: 'Set audio driver list')
 option('block_drv_rw_whitelist', type : 'string', value : '',
        description: 'set block driver read-write whitelist (by default affects only QEMU, not tools like qemu-img)')
@@ -255,6 +255,8 @@ option('oss', type: 'feature', value: 'auto',
        description: 'OSS sound support')
 option('pa', type: 'feature', value: 'auto',
        description: 'PulseAudio sound support')
+option('pipewire', type: 'feature', value: 'auto',
+       description: 'Pipewire sound support')
 option('sndio', type: 'feature', value: 'auto',
        description: 'sndio sound support')
 
diff --git a/qapi/audio.json b/qapi/audio.json
index 4e54c00f51..e03396a7bc 100644
--- a/qapi/audio.json
+++ b/qapi/audio.json
@@ -324,6 +324,47 @@
     '*out':    'AudiodevPaPerDirectionOptions',
     '*server': 'str' } }
 
+##
+# @AudiodevPipewirePerDirectionOptions:
+#
+# Options of the Pipewire backend that are used for both playback and
+# recording.
+#
+# @name: name of the sink/source to use
+#
+# @stream-name: name of the Pipewire stream created by qemu.  Can be
+#               used to identify the stream in Pipewire when you
+#               create multiple Pipewire devices or run multiple qemu
+#               instances (default: audiodev's id)
+#
+# @latency: latency you want Pipewire to achieve in microseconds
+#           (default 46000)
+#
+# Since: 8.1
+##
+{ 'struct': 'AudiodevPipewirePerDirectionOptions',
+  'base': 'AudiodevPerDirectionOptions',
+  'data': {
+    '*name': 'str',
+    '*stream-name': 'str',
+    '*latency': 'uint32' } }
+
+##
+# @AudiodevPipewireOptions:
+#
+# Options of the Pipewire audio backend.
+#
+# @in: options of the capture stream
+#
+# @out: options of the playback stream
+#
+# Since: 8.1
+##
+{ 'struct': 'AudiodevPipewireOptions',
+  'data': {
+    '*in':     'AudiodevPipewirePerDirectionOptions',
+    '*out':    'AudiodevPipewirePerDirectionOptions' } }
+
 ##
 # @AudiodevSdlPerDirectionOptions:
 #
@@ -416,6 +457,7 @@
             { 'name': 'jack', 'if': 'CONFIG_AUDIO_JACK' },
             { 'name': 'oss', 'if': 'CONFIG_AUDIO_OSS' },
             { 'name': 'pa', 'if': 'CONFIG_AUDIO_PA' },
+            { 'name': 'pipewire', 'if': 'CONFIG_AUDIO_PIPEWIRE' },
             { 'name': 'sdl', 'if': 'CONFIG_AUDIO_SDL' },
             { 'name': 'sndio', 'if': 'CONFIG_AUDIO_SNDIO' },
             { 'name': 'spice', 'if': 'CONFIG_SPICE' },
@@ -456,6 +498,8 @@
                    'if': 'CONFIG_AUDIO_OSS' },
     'pa':        { 'type': 'AudiodevPaOptions',
                    'if': 'CONFIG_AUDIO_PA' },
+    'pipewire':  { 'type': 'AudiodevPipewireOptions',
+                   'if': 'CONFIG_AUDIO_PIPEWIRE' },
     'sdl':       { 'type': 'AudiodevSdlOptions',
                    'if': 'CONFIG_AUDIO_SDL' },
     'sndio':     { 'type': 'AudiodevSndioOptions',
diff --git a/qemu-options.hx b/qemu-options.hx
index 59bdf67a2c..2d908717bd 100644
--- a/qemu-options.hx
+++ b/qemu-options.hx
@@ -779,6 +779,12 @@ DEF("audiodev", HAS_ARG, QEMU_OPTION_audiodev,
     "                in|out.name= source/sink device name\n"
     "                in|out.latency= desired latency in microseconds\n"
 #endif
+#ifdef CONFIG_AUDIO_PIPEWIRE
+    "-audiodev pipewire,id=id[,prop[=value][,...]]\n"
+    "                in|out.name= source/sink device name\n"
+    "                in|out.stream-name= name of pipewire stream\n"
+    "                in|out.latency= desired latency in microseconds\n"
+#endif
 #ifdef CONFIG_AUDIO_SDL
     "-audiodev sdl,id=id[,prop[=value][,...]]\n"
     "                in|out.buffer-count= number of buffers\n"
@@ -942,6 +948,21 @@ SRST
         Desired latency in microseconds. The PulseAudio server will try
         to honor this value but actual latencies may be lower or higher.
 
+``-audiodev pipewire,id=id[,prop[=value][,...]]``
+    Creates a backend using Pipewire. This backend is available on
+    most systems.
+
+    Pipewire specific options are:
+
+    ``in|out.latency=usecs``
+        Desired latency in microseconds.
+
+    ``in|out.name=sink``
+        Use the specified source/sink for recording/playback.
+
+    ``in|out.stream-name``
+        Specify the name of pipewire stream.
+
 ``-audiodev sdl,id=id[,prop[=value][,...]]``
     Creates a backend using SDL. This backend is available on most
     systems, but you should use your platform's native backend if
diff --git a/scripts/meson-buildoptions.sh b/scripts/meson-buildoptions.sh
index 009fab1515..ba1057b62c 100644
--- a/scripts/meson-buildoptions.sh
+++ b/scripts/meson-buildoptions.sh
@@ -1,7 +1,8 @@
 # This file is generated by meson-buildoptions.py, do not edit!
 meson_options_help() {
-  printf "%s\n" '  --audio-drv-list=CHOICES Set audio driver list [default] (choices: alsa/co'
-  printf "%s\n" '                           reaudio/default/dsound/jack/oss/pa/sdl/sndio)'
+  printf "%s\n" '  --audio-drv-list=CHOICES Set audio driver list [default] (choices: al'
+  printf "%s\n" '                           sa/coreaudio/default/dsound/jack/oss/pa/'
+  printf "%s\n" '                           pipewire/sdl/sndio)'
   printf "%s\n" '  --block-drv-ro-whitelist=VALUE'
   printf "%s\n" '                           set block driver read-only whitelist (by default'
   printf "%s\n" '                           affects only QEMU, not tools like qemu-img)'
@@ -136,6 +137,7 @@ meson_options_help() {
   printf "%s\n" '  oss             OSS sound support'
   printf "%s\n" '  pa              PulseAudio sound support'
   printf "%s\n" '  parallels       parallels image format support'
+  printf "%s\n" '  pipewire        Pipewire sound support'
   printf "%s\n" '  png             PNG support with libpng'
   printf "%s\n" '  pvrdma          Enable PVRDMA support'
   printf "%s\n" '  qcow1           qcow1 image format support'
@@ -370,6 +372,8 @@ _meson_option_parse() {
     --disable-pa) printf "%s" -Dpa=disabled ;;
     --enable-parallels) printf "%s" -Dparallels=enabled ;;
     --disable-parallels) printf "%s" -Dparallels=disabled ;;
+    --enable-pipewire) printf "%s" -Dpipewire=enabled ;;
+    --disable-pipewire) printf "%s" -Dpipewire=disabled ;;
     --with-pkgversion=*) quote_sh "-Dpkgversion=$2" ;;
     --enable-png) printf "%s" -Dpng=enabled ;;
     --disable-png) printf "%s" -Dpng=disabled ;;
-- 
2.39.1
Re: [PATCH v9] audio/pwaudio.c: Add Pipewire audio backend for QEMU
Posted by Volker Rümelin 1 year ago
Am 28.03.23 um 15:08 schrieb Dorinda Bassey:

Hi Dorinda,

> This commit adds a new audiodev backend to allow QEMU to use Pipewire as
> both an audio sink and source. This backend is available on most systems
>
> Add Pipewire entry points for QEMU Pipewire audio backend
> Add wrappers for QEMU Pipewire audio backend in qpw_pcm_ops()
> qpw_write function returns the current state of the stream to pwaudio
> and Writes some data to the server for playback streams using pipewire
> spa_ringbuffer implementation.
> qpw_read function returns the current state of the stream to pwaudio and
> reads some data from the server for capture streams using pipewire
> spa_ringbuffer implementation. These functions qpw_write and qpw_read
> are called during playback and capture.
> Added some functions that convert pw audio formats to QEMU audio format
> and vice versa which would be needed in the pipewire audio sink and
> source functions qpw_init_in() & qpw_init_out().
> These methods that implement playback and recording will create streams
> for playback and capture that will start processing and will result in
> the on_process callbacks to be called.
> Built a connection to the Pipewire sound system server in the
> qpw_audio_init() method.
>
> Signed-off-by: Dorinda Bassey <dbassey@redhat.com>
> ---
> v9:
> add code to play silence on a buffer underrun
> remove redundant block in playback and capture process functions
> refactor code for enabling/disabling audio stream
> add volume_out and volume_in pcm_ops function
> add code for in|out.name options
> add in|out.stream-name options
> fix format specifiers
> change release version
> add missing latency option
>
>   audio/audio.c                 |   3 +
>   audio/audio_template.h        |   4 +
>   audio/meson.build             |   1 +
>   audio/pwaudio.c               | 879 ++++++++++++++++++++++++++++++++++
>   audio/trace-events            |   8 +
>   meson.build                   |   8 +
>   meson_options.txt             |   4 +-
>   qapi/audio.json               |  44 ++
>   qemu-options.hx               |  21 +
>   scripts/meson-buildoptions.sh |   8 +-
>   10 files changed, 977 insertions(+), 3 deletions(-)
>   create mode 100644 audio/pwaudio.c
>
> diff --git a/audio/audio.c b/audio/audio.c
> index 70b096713c..90c7c49d11 100644
> --- a/audio/audio.c
> +++ b/audio/audio.c
> @@ -2061,6 +2061,9 @@ void audio_create_pdos(Audiodev *dev)
>   #ifdef CONFIG_AUDIO_PA
>           CASE(PA, pa, Pa);
>   #endif
> +#ifdef CONFIG_AUDIO_PIPEWIRE
> +        CASE(PIPEWIRE, pipewire, Pipewire);
> +#endif
>   #ifdef CONFIG_AUDIO_SDL
>           CASE(SDL, sdl, Sdl);
>   #endif
> diff --git a/audio/audio_template.h b/audio/audio_template.h
> index e42326c20d..dc0c74aa74 100644
> --- a/audio/audio_template.h
> +++ b/audio/audio_template.h
> @@ -362,6 +362,10 @@ AudiodevPerDirectionOptions *glue(audio_get_pdo_, TYPE)(Audiodev *dev)
>       case AUDIODEV_DRIVER_PA:
>           return qapi_AudiodevPaPerDirectionOptions_base(dev->u.pa.TYPE);
>   #endif
> +#ifdef CONFIG_AUDIO_PIPEWIRE
> +    case AUDIODEV_DRIVER_PIPEWIRE:
> +        return qapi_AudiodevPipewirePerDirectionOptions_base(dev->u.pipewire.TYPE);
> +#endif
>   #ifdef CONFIG_AUDIO_SDL
>       case AUDIODEV_DRIVER_SDL:
>           return qapi_AudiodevSdlPerDirectionOptions_base(dev->u.sdl.TYPE);
> diff --git a/audio/meson.build b/audio/meson.build
> index 0722224ba9..65a49c1a10 100644
> --- a/audio/meson.build
> +++ b/audio/meson.build
> @@ -19,6 +19,7 @@ foreach m : [
>     ['sdl', sdl, files('sdlaudio.c')],
>     ['jack', jack, files('jackaudio.c')],
>     ['sndio', sndio, files('sndioaudio.c')],
> +  ['pipewire', pipewire, files('pwaudio.c')],
>     ['spice', spice, files('spiceaudio.c')]
>   ]
>     if m[1].found()
> diff --git a/audio/pwaudio.c b/audio/pwaudio.c
> new file mode 100644
> index 0000000000..ca83bc55f9
> --- /dev/null
> +++ b/audio/pwaudio.c
> @@ -0,0 +1,879 @@
> +/*
> + * QEMU Pipewire audio driver
> + *
> + * Copyright (c) 2023 Red Hat Inc.
> + *
> + * Author: Dorinda Bassey       <dbassey@redhat.com>
> + *
> + * SPDX-License-Identifier: GPL-2.0-or-later
> + */
> +
> +#include "qemu/osdep.h"
> +#include "qemu/module.h"
> +#include "audio.h"
> +#include <errno.h>
> +#include "qemu/error-report.h"
> +#include <spa/param/audio/format-utils.h>
> +#include <spa/utils/ringbuffer.h>
> +#include <spa/utils/result.h>
> +#include <spa/param/props.h>
> +
> +#include <pipewire/pipewire.h>
> +#include "trace.h"
> +
> +#define AUDIO_CAP "pipewire"
> +#define RINGBUFFER_SIZE    (1u << 22)
> +#define RINGBUFFER_MASK    (RINGBUFFER_SIZE - 1)
> +
> +#include "audio_int.h"
> +
> +enum {
> +    MODE_SINK,
> +    MODE_SOURCE
> +};
> +
> +typedef struct pwvolume {
> +    uint32_t channels;
> +    float values[SPA_AUDIO_MAX_CHANNELS];
> +} pwvolume;
> +
> +typedef struct pwaudio {
> +    Audiodev *dev;
> +    struct pw_thread_loop *thread_loop;
> +    struct pw_context *context;
> +
> +    struct pw_core *core;
> +    struct spa_hook core_listener;
> +    int seq;
> +} pwaudio;
> +
> +typedef struct PWVoice {
> +    pwaudio *g;
> +    struct pw_stream *stream;
> +    struct spa_hook stream_listener;
> +    struct spa_audio_info_raw info;
> +    uint32_t highwater_mark;
> +    uint32_t frame_size;
> +    struct spa_ringbuffer ring;
> +    uint8_t buffer[RINGBUFFER_SIZE];
> +
> +    uint32_t mode;
> +    struct pw_properties *props;
> +    pwvolume volume;
> +    bool muted;
> +} PWVoice;
> +
> +typedef struct PWVoiceOut {
> +    HWVoiceOut hw;
> +    PWVoice v;
> +} PWVoiceOut;
> +
> +typedef struct PWVoiceIn {
> +    HWVoiceIn hw;
> +    PWVoice v;
> +} PWVoiceIn;
> +
> +static void
> +stream_destroy(void *data)
> +{
> +    PWVoice *v = (PWVoice *) data;
> +    spa_hook_remove(&v->stream_listener);
> +    v->stream = NULL;
> +}
> +
> +/* output data processing function to read stuffs from the buffer */
> +static void
> +playback_on_process(void *data)
> +{
> +    PWVoice *v = (PWVoice *) data;
> +    void *p;
> +    struct pw_buffer *b;
> +    struct spa_buffer *buf;
> +    uint32_t req, index, n_bytes;
> +    int32_t avail;
> +
> +    if (!v->stream) {
> +        return;
> +    }
> +
> +    /* obtain a buffer to read from */
> +    b = pw_stream_dequeue_buffer(v->stream);
> +    if (b == NULL) {
> +        error_report("out of buffers: %s", strerror(errno));
> +        return;
> +    }
> +
> +    buf = b->buffer;
> +    p = buf->datas[0].data;
> +    if (p == NULL) {
> +        return;
> +    }
> +    /* calculate the total no of bytes to read data from buffer */
> +    req = b->requested * v->frame_size;
> +    if (req == 0) {
> +        req = (uint64_t)v->g->dev->timer_period * v->info.rate
> +                * 1 / 2 / 1000000 * v->frame_size;
> +    }
> +    n_bytes = SPA_MIN(req, buf->datas[0].maxsize);
> +
> +    /* get no of available bytes to read data from buffer */
> +
> +    avail = spa_ringbuffer_get_read_index(&v->ring, &index);
> +
> +
> +    if (avail == 0) {
> +        memset(p, 0, n_bytes);

Filling a buffer with zeros to produce silence still wrong for unsigned 
samples. For example, a 0 in SPA_AUDIO_FORMAT_U8 format maps to -1.0 in 
SPA_AUDIO_FORMAT_F32.

> +    }
> +
> +    if (avail < (int32_t) n_bytes) {
> +        n_bytes = avail;
> +    }
> +

This is a bug. On a buffer underrun, the buffer filled with silence is 
dropped.

> +    spa_ringbuffer_read_data(&v->ring,
> +                                v->buffer, RINGBUFFER_SIZE,
> +                                index & RINGBUFFER_MASK, p, n_bytes);
> +
> +    index += n_bytes;
> +    spa_ringbuffer_read_update(&v->ring, index);
> +
> +    buf->datas[0].chunk->offset = 0;
> +    buf->datas[0].chunk->stride = v->frame_size;
> +    buf->datas[0].chunk->size = n_bytes;
> +
> +    /* queue the buffer for playback */
> +    pw_stream_queue_buffer(v->stream, b);
> +}
> +
> +/* output data processing function to generate stuffs in the buffer */
> +static void
> +capture_on_process(void *data)
> +{
> +    PWVoice *v = (PWVoice *) data;
> +    void *p;
> +    struct pw_buffer *b;
> +    struct spa_buffer *buf;
> +    int32_t filled;
> +    uint32_t index, offs, n_bytes;
> +
> +    if (!v->stream) {
> +        return;
> +    }
> +
> +    /* obtain a buffer */
> +    b = pw_stream_dequeue_buffer(v->stream);
> +    if (b == NULL) {
> +        error_report("out of buffers: %s", strerror(errno));
> +        return;
> +    }
> +
> +    /* Write data into buffer */
> +    buf = b->buffer;
> +    p = buf->datas[0].data;
> +    if (p == NULL) {
> +        return;
> +    }
> +    offs = SPA_MIN(buf->datas[0].chunk->offset, buf->datas[0].maxsize);
> +    n_bytes = SPA_MIN(buf->datas[0].chunk->size, buf->datas[0].maxsize - offs);
> +
> +    filled = spa_ringbuffer_get_write_index(&v->ring, &index);
> +
> +
> +    if (filled < 0) {
> +        error_report("%p: underrun write:%u filled:%d", p, index, filled);
> +    } else {
> +        if ((uint32_t) filled + n_bytes > RINGBUFFER_SIZE) {
> +            error_report("%p: overrun write:%u filled:%d + size:%u > max:%u",
> +            p, index, filled, n_bytes, RINGBUFFER_SIZE);
> +        }
> +    }
> +    spa_ringbuffer_write_data(&v->ring,
> +                                v->buffer, RINGBUFFER_SIZE,
> +                                index & RINGBUFFER_MASK,
> +                                SPA_PTROFF(p, offs, void), n_bytes);
> +    index += n_bytes;
> +    spa_ringbuffer_write_update(&v->ring, index);
> +
> +    /* queue the buffer for playback */
> +    pw_stream_queue_buffer(v->stream, b);
> +}
> +
> +static void
> +on_stream_state_changed(void *_data, enum pw_stream_state old,
> +                        enum pw_stream_state state, const char *error)
> +{
> +    PWVoice *v = (PWVoice *) _data;
> +
> +    trace_pw_state_changed(pw_stream_state_as_string(state));
> +
> +    switch (state) {
> +    case PW_STREAM_STATE_ERROR:
> +    case PW_STREAM_STATE_UNCONNECTED:
> +        {
> +            break;
> +        }
> +    case PW_STREAM_STATE_PAUSED:
> +        trace_pw_node(pw_stream_get_node_id(v->stream));
> +        break;
> +    case PW_STREAM_STATE_CONNECTING:
> +    case PW_STREAM_STATE_STREAMING:
> +        break;
> +    }
> +}
> +
> +static const struct pw_stream_events capture_stream_events = {
> +    PW_VERSION_STREAM_EVENTS,
> +    .destroy = stream_destroy,
> +    .state_changed = on_stream_state_changed,
> +    .process = capture_on_process
> +};
> +
> +static const struct pw_stream_events playback_stream_events = {
> +    PW_VERSION_STREAM_EVENTS,
> +    .destroy = stream_destroy,
> +    .state_changed = on_stream_state_changed,
> +    .process = playback_on_process
> +};
> +
> +static size_t
> +qpw_read(HWVoiceIn *hw, void *data, size_t len)
> +{
> +    PWVoiceIn *pw = (PWVoiceIn *) hw;
> +    PWVoice *v = &pw->v;
> +    pwaudio *c = v->g;
> +    const char *error = NULL;
> +    size_t l;
> +    int32_t avail;
> +    uint32_t index;
> +
> +    pw_thread_loop_lock(c->thread_loop);
> +    if (pw_stream_get_state(v->stream, &error) != PW_STREAM_STATE_STREAMING) {
> +        /* wait for stream to become ready */
> +        l = 0;
> +        goto done_unlock;
> +    }
> +    /* get no of available bytes to read data from buffer */
> +    avail = spa_ringbuffer_get_read_index(&v->ring, &index);
> +
> +    trace_pw_read(avail, index, len);
> +
> +    if (avail < (int32_t) len) {
> +        len = avail;
> +    }
> +
> +    spa_ringbuffer_read_data(&v->ring,
> +                             v->buffer, RINGBUFFER_SIZE,
> +                             index & RINGBUFFER_MASK, data, len);
> +    index += len;
> +    spa_ringbuffer_read_update(&v->ring, index);
> +    l = len;
> +
> +done_unlock:
> +    pw_thread_loop_unlock(c->thread_loop);
> +    return l;
> +}
> +
> +static size_t qpw_buffer_get_free(HWVoiceOut *hw)
> +{
> +    PWVoiceOut *pw = (PWVoiceOut *)hw;
> +    PWVoice *v = &pw->v;
> +    pwaudio *c = v->g;
> +    const char *error = NULL;
> +    int32_t filled, avail;
> +    uint32_t index;
> +
> +    pw_thread_loop_lock(c->thread_loop);
> +    if (pw_stream_get_state(v->stream, &error) != PW_STREAM_STATE_STREAMING) {
> +        /* wait for stream to become ready */
> +        avail = 0;
> +        goto done_unlock;
> +    }
> +
> +    filled = spa_ringbuffer_get_write_index(&v->ring, &index);
> +    avail = v->highwater_mark - filled;
> +
> +done_unlock:
> +    pw_thread_loop_unlock(c->thread_loop);
> +    return avail;
> +}
> +
> +static size_t
> +qpw_write(HWVoiceOut *hw, void *data, size_t len)
> +{
> +    PWVoiceOut *pw = (PWVoiceOut *) hw;
> +    PWVoice *v = &pw->v;
> +    pwaudio *c = v->g;
> +    const char *error = NULL;
> +    int32_t filled, avail;
> +    uint32_t index;
> +
> +    pw_thread_loop_lock(c->thread_loop);
> +    if (pw_stream_get_state(v->stream, &error) != PW_STREAM_STATE_STREAMING) {
> +        /* wait for stream to become ready */
> +        len = 0;
> +        goto done_unlock;
> +    }
> +    filled = spa_ringbuffer_get_write_index(&v->ring, &index);
> +    avail = v->highwater_mark - filled;
> +
> +    trace_pw_write(filled, avail, index, len);
> +
> +    if (len > avail) {
> +        len = avail;
> +    }
> +
> +    if (filled < 0) {
> +        error_report("%p: underrun write:%u filled:%d", pw, index, filled);
> +    } else {
> +        if ((uint32_t) filled + len > RINGBUFFER_SIZE) {
> +            error_report("%p: overrun write:%u filled:%d + size:%zu > max:%u",
> +            pw, index, filled, len, RINGBUFFER_SIZE);
> +        }
> +    }
> +
> +    spa_ringbuffer_write_data(&v->ring,
> +                                v->buffer, RINGBUFFER_SIZE,
> +                                index & RINGBUFFER_MASK, data, len);
> +    index += len;
> +    spa_ringbuffer_write_update(&v->ring, index);
> +
> +done_unlock:
> +    pw_thread_loop_unlock(c->thread_loop);
> +    return len;
> +}
> +
> +static int
> +audfmt_to_pw(AudioFormat fmt, int endianness)
> +{
> +    int format;
> +
> +    switch (fmt) {
> +    case AUDIO_FORMAT_S8:
> +        format = SPA_AUDIO_FORMAT_S8;
> +        break;
> +    case AUDIO_FORMAT_U8:
> +        format = SPA_AUDIO_FORMAT_U8;
> +        break;
> +    case AUDIO_FORMAT_S16:
> +        format = endianness ? SPA_AUDIO_FORMAT_S16_BE : SPA_AUDIO_FORMAT_S16_LE;
> +        break;
> +    case AUDIO_FORMAT_U16:
> +        format = endianness ? SPA_AUDIO_FORMAT_U16_BE : SPA_AUDIO_FORMAT_U16_LE;
> +        break;
> +    case AUDIO_FORMAT_S32:
> +        format = endianness ? SPA_AUDIO_FORMAT_S32_BE : SPA_AUDIO_FORMAT_S32_LE;
> +        break;
> +    case AUDIO_FORMAT_U32:
> +        format = endianness ? SPA_AUDIO_FORMAT_U32_BE : SPA_AUDIO_FORMAT_U32_LE;
> +        break;
> +    case AUDIO_FORMAT_F32:
> +        format = endianness ? SPA_AUDIO_FORMAT_F32_BE : SPA_AUDIO_FORMAT_F32_LE;
> +        break;
> +    default:
> +        dolog("Internal logic error: Bad audio format %d\n", fmt);
> +        format = SPA_AUDIO_FORMAT_U8;
> +        break;
> +    }
> +    return format;
> +}
> +
> +static AudioFormat
> +pw_to_audfmt(enum spa_audio_format fmt, int *endianness,
> +             uint32_t *frame_size)
> +{
> +    switch (fmt) {
> +    case SPA_AUDIO_FORMAT_S8:
> +        *frame_size = 1;
> +        return AUDIO_FORMAT_S8;
> +    case SPA_AUDIO_FORMAT_U8:
> +        *frame_size = 1;
> +        return AUDIO_FORMAT_U8;
> +    case SPA_AUDIO_FORMAT_S16_BE:
> +        *frame_size = 2;
> +        *endianness = 1;
> +        return AUDIO_FORMAT_S16;
> +    case SPA_AUDIO_FORMAT_S16_LE:
> +        *frame_size = 2;
> +        *endianness = 0;
> +        return AUDIO_FORMAT_S16;
> +    case SPA_AUDIO_FORMAT_U16_BE:
> +        *frame_size = 2;
> +        *endianness = 1;
> +        return AUDIO_FORMAT_U16;
> +    case SPA_AUDIO_FORMAT_U16_LE:
> +        *frame_size = 2;
> +        *endianness = 0;
> +        return AUDIO_FORMAT_U16;
> +    case SPA_AUDIO_FORMAT_S32_BE:
> +        *frame_size = 4;
> +        *endianness = 1;
> +        return AUDIO_FORMAT_S32;
> +    case SPA_AUDIO_FORMAT_S32_LE:
> +        *frame_size = 4;
> +        *endianness = 0;
> +        return AUDIO_FORMAT_S32;
> +    case SPA_AUDIO_FORMAT_U32_BE:
> +        *frame_size = 4;
> +        *endianness = 1;
> +        return AUDIO_FORMAT_U32;
> +    case SPA_AUDIO_FORMAT_U32_LE:
> +        *frame_size = 4;
> +        *endianness = 0;
> +        return AUDIO_FORMAT_U32;
> +    case SPA_AUDIO_FORMAT_F32_BE:
> +        *frame_size = 4;
> +        *endianness = 1;
> +        return AUDIO_FORMAT_F32;
> +    case SPA_AUDIO_FORMAT_F32_LE:
> +        *frame_size = 4;
> +        *endianness = 0;
> +        return AUDIO_FORMAT_F32;
> +    default:
> +        *frame_size = 1;
> +        dolog("Internal logic error: Bad spa_audio_format %d\n", fmt);
> +        return AUDIO_FORMAT_U8;
> +    }
> +}
> +
> +static int
> +create_stream(pwaudio *c, PWVoice *v, const char *stream_name, const char *name)
> +{
> +    int res;
> +    uint32_t n_params;
> +    const struct spa_pod *params[2];
> +    uint8_t buffer[1024];
> +    struct spa_pod_builder b;
> +
> +    v->props = pw_properties_new(NULL, NULL);
> +    pw_properties_setf(v->props, PW_KEY_NODE_LATENCY, "%" PRIu64 "/%u",
> +                       (uint64_t)v->g->dev->timer_period * v->info.rate
> +                       * 3 / 4 / 1000000, v->info.rate);
> +    if (name) {
> +        pw_properties_set(v->props, PW_KEY_TARGET_OBJECT, name);
> +    }
> +    v->stream = pw_stream_new(c->core, stream_name, v->props);
> +
> +    if (v->stream == NULL) {
> +        return -1;
> +    }
> +
> +    if (v->mode == MODE_SOURCE) {
> +        pw_stream_add_listener(v->stream,
> +                            &v->stream_listener, &capture_stream_events, v);
> +    } else {
> +        pw_stream_add_listener(v->stream,
> +                            &v->stream_listener, &playback_stream_events, v);
> +    }
> +
> +    n_params = 0;
> +    spa_pod_builder_init(&b, buffer, sizeof(buffer));
> +    params[n_params++] = spa_format_audio_raw_build(&b,
> +                            SPA_PARAM_EnumFormat,
> +                            &v->info);
> +
> +    /* connect the stream to a sink or source */
> +    res = pw_stream_connect(v->stream,
> +                            v->mode ==
> +                            MODE_SOURCE ? PW_DIRECTION_INPUT :
> +                            PW_DIRECTION_OUTPUT, PW_ID_ANY,
> +                            PW_STREAM_FLAG_AUTOCONNECT |
> +                            PW_STREAM_FLAG_INACTIVE |
> +                            PW_STREAM_FLAG_MAP_BUFFERS |
> +                            PW_STREAM_FLAG_RT_PROCESS, params, n_params);
> +    if (res < 0) {
> +        pw_stream_destroy(v->stream);
> +        return -1;
> +    }
> +
> +    return 0;
> +}
> +
> +static int
> +qpw_stream_new(pwaudio *c, PWVoice *v,
> +               const char *stream_name, const char *name)
> +{
> +    int r;
> +
> +    switch (v->info.channels) {
> +    case 8:
> +        v->info.position[0] = SPA_AUDIO_CHANNEL_FL;
> +        v->info.position[1] = SPA_AUDIO_CHANNEL_FR;
> +        v->info.position[2] = SPA_AUDIO_CHANNEL_FC;
> +        v->info.position[3] = SPA_AUDIO_CHANNEL_LFE;
> +        v->info.position[4] = SPA_AUDIO_CHANNEL_RL;
> +        v->info.position[5] = SPA_AUDIO_CHANNEL_RR;
> +        v->info.position[6] = SPA_AUDIO_CHANNEL_SL;
> +        v->info.position[7] = SPA_AUDIO_CHANNEL_SR;
> +        break;
> +    case 6:
> +        v->info.position[0] = SPA_AUDIO_CHANNEL_FL;
> +        v->info.position[1] = SPA_AUDIO_CHANNEL_FR;
> +        v->info.position[2] = SPA_AUDIO_CHANNEL_FC;
> +        v->info.position[3] = SPA_AUDIO_CHANNEL_LFE;
> +        v->info.position[4] = SPA_AUDIO_CHANNEL_RL;
> +        v->info.position[5] = SPA_AUDIO_CHANNEL_RR;
> +        break;
> +    case 5:
> +        v->info.position[0] = SPA_AUDIO_CHANNEL_FL;
> +        v->info.position[1] = SPA_AUDIO_CHANNEL_FR;
> +        v->info.position[2] = SPA_AUDIO_CHANNEL_FC;
> +        v->info.position[3] = SPA_AUDIO_CHANNEL_LFE;
> +        v->info.position[4] = SPA_AUDIO_CHANNEL_RC;
> +        break;
> +    case 4:
> +        v->info.position[0] = SPA_AUDIO_CHANNEL_FL;
> +        v->info.position[1] = SPA_AUDIO_CHANNEL_FR;
> +        v->info.position[2] = SPA_AUDIO_CHANNEL_FC;
> +        v->info.position[3] = SPA_AUDIO_CHANNEL_RC;
> +        break;
> +    case 3:
> +        v->info.position[0] = SPA_AUDIO_CHANNEL_FL;
> +        v->info.position[1] = SPA_AUDIO_CHANNEL_FR;
> +        v->info.position[2] = SPA_AUDIO_CHANNEL_LFE;
> +        break;
> +    case 2:
> +        v->info.position[0] = SPA_AUDIO_CHANNEL_FL;
> +        v->info.position[1] = SPA_AUDIO_CHANNEL_FR;
> +        break;
> +    case 1:
> +        v->info.position[0] = SPA_AUDIO_CHANNEL_MONO;
> +        break;
> +    default:
> +        for (size_t i = 0; i < v->info.channels; i++) {
> +            v->info.position[i] = SPA_AUDIO_CHANNEL_UNKNOWN;
> +        }
> +        break;
> +    }
> +
> +    /* create a new unconnected pwstream */
> +    r = create_stream(c, v, stream_name, name);
> +    if (r < 0) {
> +        AUD_log(AUDIO_CAP, "Failed to create stream.");
> +        return -1;
> +    }
> +
> +    return r;
> +}
> +
> +static int
> +qpw_init_out(HWVoiceOut *hw, struct audsettings *as, void *drv_opaque)
> +{
> +    PWVoiceOut *pw = (PWVoiceOut *) hw;
> +    PWVoice *v = &pw->v;
> +    struct audsettings obt_as = *as;
> +    pwaudio *c = v->g = drv_opaque;
> +    AudiodevPipewireOptions *popts = &c->dev->u.pipewire;
> +    AudiodevPipewirePerDirectionOptions *ppdo = popts->out;
> +    int r;
> +
> +    v->mode = MODE_SINK;
> +
> +    pw_thread_loop_lock(c->thread_loop);
> +
> +    v->info.format = audfmt_to_pw(as->fmt, as->endianness);
> +    v->info.channels = as->nchannels;
> +    v->info.rate = as->freq;
> +
> +    obt_as.fmt =
> +        pw_to_audfmt(v->info.format, &obt_as.endianness, &v->frame_size);
> +    v->frame_size *= as->nchannels;
> +
> +    /* call the function that creates a new stream for playback */
> +    r = qpw_stream_new(c, v, ppdo->stream_name ? : c->dev->id, ppdo->name);
> +    if (r < 0) {
> +        error_report("qpw_stream_new for playback failed");
> +        pw_thread_loop_unlock(c->thread_loop);
> +        return -1;
> +    }
> +
> +    /* report the audio format we support */
> +    audio_pcm_init_info(&hw->info, &obt_as);
> +
> +    /* report the buffer size to qemu */
> +    hw->samples = audio_buffer_frames(
> +        qapi_AudiodevPipewirePerDirectionOptions_base(ppdo), &obt_as, 46440);
> +    v->highwater_mark = MIN(RINGBUFFER_SIZE,
> +                            (ppdo->has_latency ? ppdo->latency : 46440)
> +                            * (uint64_t)v->info.rate / 1000000 * v->frame_size);
> +
> +    pw_thread_loop_unlock(c->thread_loop);
> +    return 0;
> +}
> +
> +static int
> +qpw_init_in(HWVoiceIn *hw, struct audsettings *as, void *drv_opaque)
> +{
> +    PWVoiceIn *pw = (PWVoiceIn *) hw;
> +    PWVoice *v = &pw->v;
> +    struct audsettings obt_as = *as;
> +    pwaudio *c = v->g = drv_opaque;
> +    AudiodevPipewireOptions *popts = &c->dev->u.pipewire;
> +    AudiodevPipewirePerDirectionOptions *ppdo = popts->in;
> +    int r;
> +
> +    v->mode = MODE_SOURCE;
> +    pw_thread_loop_lock(c->thread_loop);
> +
> +    v->info.format = audfmt_to_pw(as->fmt, as->endianness);
> +    v->info.channels = as->nchannels;
> +    v->info.rate = as->freq;
> +
> +    obt_as.fmt =
> +        pw_to_audfmt(v->info.format, &obt_as.endianness, &v->frame_size);
> +    v->frame_size *= as->nchannels;
> +
> +    /* call the function that creates a new stream for recording */
> +    r = qpw_stream_new(c, v, ppdo->stream_name ? : c->dev->id, ppdo->name);
> +    if (r < 0) {
> +        error_report("qpw_stream_new for recording failed");
> +        pw_thread_loop_unlock(c->thread_loop);
> +        return -1;
> +    }
> +
> +    /* report the audio format we support */
> +    audio_pcm_init_info(&hw->info, &obt_as);
> +
> +    /* report the buffer size to qemu */
> +    hw->samples = audio_buffer_frames(
> +        qapi_AudiodevPipewirePerDirectionOptions_base(ppdo), &obt_as, 46440);
> +
> +    pw_thread_loop_unlock(c->thread_loop);
> +    return 0;
> +}
> +
> +static void
> +qpw_fini_out(HWVoiceOut *hw)
> +{
> +    PWVoiceOut *pw = (PWVoiceOut *) hw;
> +    PWVoice *v = &pw->v;
> +
> +    if (v->stream) {
> +        pwaudio *c = v->g;
> +        pw_thread_loop_lock(c->thread_loop);
> +        pw_stream_destroy(v->stream);
> +        v->stream = NULL;
> +        pw_thread_loop_unlock(c->thread_loop);
> +    }
> +}
> +
> +static void
> +qpw_fini_in(HWVoiceIn *hw)
> +{
> +    PWVoiceIn *pw = (PWVoiceIn *) hw;
> +    PWVoice *v = &pw->v;
> +
> +    if (v->stream) {
> +        pwaudio *c = v->g;
> +        pw_thread_loop_lock(c->thread_loop);
> +        pw_stream_destroy(v->stream);
> +        v->stream = NULL;
> +        pw_thread_loop_unlock(c->thread_loop);
> +    }
> +}
> +
> +static void
> +qpw_enable_out(HWVoiceOut *hw, bool enable)
> +{
> +    PWVoiceOut *po = (PWVoiceOut *) hw;
> +    PWVoice *v = &po->v;
> +    pw_stream_set_active(v->stream, enable);

Why don't you need a lock here? Is pw_stream_set_active() thread safe?

> +}
> +
> +static void
> +qpw_enable_in(HWVoiceIn *hw, bool enable)
> +{
> +    PWVoiceIn *pi = (PWVoiceIn *) hw;
> +    PWVoice *v = &pi->v;
> +    pw_stream_set_active(v->stream, enable);

Same here.

> +}
> +
> +static void
> +qpw_volume_out(HWVoiceOut *hw, Volume *vol)
> +{
> +    PWVoiceOut *pw = (PWVoiceOut *) hw;
> +    PWVoice *v = &pw->v;
> +    pwaudio *c = v->g;
> +    int i, ret;
> +
> +    pw_thread_loop_lock(c->thread_loop);
> +    v->volume.channels = vol->channels;
> +
> +    for (i = 0; i < vol->channels; ++i) {
> +        v->volume.values[i] = vol->vol[i] / 100;

You only have the three volume levels 2.0, 1.0 and 0.0 while vol[i] has 
256 levels.

> +    }
> +
> +    ret = pw_stream_set_control(v->stream,
> +        SPA_PROP_channelVolumes, v->volume.channels, v->volume.values, 0);
> +    trace_pw_vol(ret == 0 ? "success" : "failed");
> +
> +    v->muted = vol->mute;
> +    float val = v->muted ? 1.f : 0.f;
> +    ret = pw_stream_set_control(v->stream, SPA_PROP_mute, 1, &val, 0);
> +    pw_thread_loop_unlock(c->thread_loop);
> +}
> +
> +static void
> +qpw_volume_in(HWVoiceIn *hw, Volume *vol)
> +{
> +    PWVoiceIn *pw = (PWVoiceIn *) hw;
> +    PWVoice *v = &pw->v;
> +    pwaudio *c = v->g;
> +    int i, ret;
> +
> +    pw_thread_loop_lock(c->thread_loop);
> +    v->volume.channels = vol->channels;
> +
> +    for (i = 0; i < vol->channels; ++i) {
> +        v->volume.values[i] = vol->vol[i] / 100;

Same here.

> +    }
> +
> +    ret = pw_stream_set_control(v->stream,
> +        SPA_PROP_channelVolumes, v->volume.channels, v->volume.values, 0);
> +    trace_pw_vol(ret == 0 ? "success" : "failed");
> +
> +    v->muted = vol->mute;
> +    float val = v->muted ? 1.f : 0.f;
> +    ret = pw_stream_set_control(v->stream, SPA_PROP_mute, 1, &val, 0);
> +    pw_thread_loop_unlock(c->thread_loop);
> +}
> +
> +static void
> +on_core_error(void *data, uint32_t id, int seq, int res, const char *message)
> +{
> +    pwaudio *pw = data;
> +
> +    error_report("error id:%u seq:%d res:%d (%s): %s",
> +                id, seq, res, spa_strerror(res), message);
> +
> +    /* stop and exit the thread loop */
> +    pw_thread_loop_signal(pw->thread_loop, FALSE);
> +}
> +
> +static void
> +on_core_done(void *data, uint32_t id, int seq)
> +{
> +    pwaudio *pw = data;
> +    if (id == PW_ID_CORE) {
> +        pw->seq = seq;
> +        /* stop and exit the thread loop */
> +        pw_thread_loop_signal(pw->thread_loop, FALSE);
> +    }
> +}
> +
> +static const struct pw_core_events core_events = {
> +    PW_VERSION_CORE_EVENTS,
> +    .done = on_core_done,
> +    .error = on_core_error,
> +};
> +
> +static void *
> +qpw_audio_init(Audiodev *dev)
> +{
> +    g_autofree pwaudio *pw = g_new0(pwaudio, 1);
> +    pw_init(NULL, NULL);
> +
> +    trace_pw_audio_init();
> +    assert(dev->driver == AUDIODEV_DRIVER_PIPEWIRE);
> +
> +    pw->dev = dev;
> +    pw->thread_loop = pw_thread_loop_new("Pipewire thread loop", NULL);
> +    if (pw->thread_loop == NULL) {
> +        error_report("Could not create Pipewire loop");
> +        goto fail;
> +    }
> +
> +    pw->context =
> +        pw_context_new(pw_thread_loop_get_loop(pw->thread_loop), NULL, 0);
> +    if (pw->context == NULL) {
> +        error_report("Could not create Pipewire context");
> +        goto fail;
> +    }
> +
> +    if (pw_thread_loop_start(pw->thread_loop) < 0) {
> +        error_report("Could not start Pipewire loop");
> +        goto fail;
> +    }
> +
> +    pw_thread_loop_lock(pw->thread_loop);
> +
> +    pw->core = pw_context_connect(pw->context, NULL, 0);
> +    if (pw->core == NULL) {
> +        pw_thread_loop_unlock(pw->thread_loop);
> +        goto fail;
> +    }
> +
> +    pw_core_add_listener(pw->core, &pw->core_listener, &core_events, pw);
> +
> +    pw_thread_loop_unlock(pw->thread_loop);
> +
> +    return g_steal_pointer(&pw);
> +
> +fail:
> +    AUD_log(AUDIO_CAP, "Failed to initialize PW context");
> +    if (pw->thread_loop) {
> +        pw_thread_loop_stop(pw->thread_loop);
> +        g_clear_pointer(&pw->thread_loop, pw_thread_loop_destroy);
> +    }
> +    if (pw->context) {
> +        g_clear_pointer(&pw->context, pw_context_destroy);
> +    }
> +    return NULL;
> +}
> +
> +static void
> +qpw_audio_fini(void *opaque)
> +{
> +    pwaudio *pw = opaque;
> +
> +    pw_thread_loop_stop(pw->thread_loop);
> +
> +    if (pw->core) {
> +        spa_hook_remove(&pw->core_listener);
> +        spa_zero(pw->core_listener);
> +        pw_core_disconnect(pw->core);
> +    }
> +
> +    if (pw->context) {
> +        pw_context_destroy(pw->context);
> +    }
> +    pw_thread_loop_destroy(pw->thread_loop);
> +
> +    g_free(pw);
> +}
> +
> +static struct audio_pcm_ops qpw_pcm_ops = {
> +    .init_out = qpw_init_out,
> +    .fini_out = qpw_fini_out,
> +    .write = qpw_write,
> +    .buffer_get_free = qpw_buffer_get_free,
> +    .run_buffer_out = audio_generic_run_buffer_out,
> +    .enable_out = qpw_enable_out,
> +    .volume_out = qpw_volume_out,
> +    .volume_in = qpw_volume_in,
> +
> +    .init_in = qpw_init_in,
> +    .fini_in = qpw_fini_in,
> +    .read = qpw_read,
> +    .run_buffer_in = audio_generic_run_buffer_in,
> +    .enable_in = qpw_enable_in
> +};
> +
> +static struct audio_driver pw_audio_driver = {
> +    .name = "pipewire",
> +    .descr = "http://www.pipewire.org/",
> +    .init = qpw_audio_init,
> +    .fini = qpw_audio_fini,
> +    .pcm_ops = &qpw_pcm_ops,
> +    .can_be_default = 1,
> +    .max_voices_out = INT_MAX,
> +    .max_voices_in = INT_MAX,
> +    .voice_size_out = sizeof(PWVoiceOut),
> +    .voice_size_in = sizeof(PWVoiceIn),
> +};
> +
> +static void
> +register_audio_pw(void)
> +{
> +    audio_driver_register(&pw_audio_driver);
> +}
> +
> +type_init(register_audio_pw);
> diff --git a/audio/trace-events b/audio/trace-events
> index e1ab643add..59ec817c9d 100644
> --- a/audio/trace-events
> +++ b/audio/trace-events
> @@ -18,6 +18,14 @@ dbus_audio_register(const char *s, const char *dir) "sender = %s, dir = %s"
>   dbus_audio_put_buffer_out(size_t len) "len = %zu"
>   dbus_audio_read(size_t len) "len = %zu"
>   
> +# pwaudio.c
> +pw_state_changed(const char *s) "stream state: %s"
> +pw_node(int nodeid) "node id: %d"
> +pw_read(int32_t avail, uint32_t index, size_t len) "avail=%d index=%u len=%zu"
> +pw_write(int32_t filled, int32_t avail, uint32_t index, size_t len) "filled=%d avail=%d index=%u len=%zu"
> +pw_vol(const char *ret) "set volume: %s"
> +pw_audio_init(void) "Initialize Pipewire context"
> +
>   # audio.c
>   audio_timer_start(int interval) "interval %d ms"
>   audio_timer_stop(void) ""
> diff --git a/meson.build b/meson.build
> index 29f8644d6d..31bf280c0d 100644
> --- a/meson.build
> +++ b/meson.build
> @@ -730,6 +730,12 @@ if not get_option('jack').auto() or have_system
>     jack = dependency('jack', required: get_option('jack'),
>                       method: 'pkg-config', kwargs: static_kwargs)
>   endif
> +pipewire = not_found
> +if not get_option('pipewire').auto() or (targetos == 'linux' and have_system)
> +  pipewire = dependency('libpipewire-0.3', version: '>=0.3.60',
> +                    required: get_option('pipewire'),
> +                    method: 'pkg-config', kwargs: static_kwargs)
> +endif
>   sndio = not_found
>   if not get_option('sndio').auto() or have_system
>     sndio = dependency('sndio', required: get_option('sndio'),
> @@ -1667,6 +1673,7 @@ if have_system
>       'jack': jack.found(),
>       'oss': oss.found(),
>       'pa': pulse.found(),
> +    'pipewire': pipewire.found(),
>       'sdl': sdl.found(),
>       'sndio': sndio.found(),
>     }
> @@ -3980,6 +3987,7 @@ if targetos == 'linux'
>     summary_info += {'ALSA support':    alsa}
>     summary_info += {'PulseAudio support': pulse}
>   endif
> +summary_info += {'Pipewire support':   pipewire}
>   summary_info += {'JACK support':      jack}
>   summary_info += {'brlapi support':    brlapi}
>   summary_info += {'vde support':       vde}
> diff --git a/meson_options.txt b/meson_options.txt
> index fc9447d267..9ae1ec7f47 100644
> --- a/meson_options.txt
> +++ b/meson_options.txt
> @@ -21,7 +21,7 @@ option('tls_priority', type : 'string', value : 'NORMAL',
>   option('default_devices', type : 'boolean', value : true,
>          description: 'Include a default selection of devices in emulators')
>   option('audio_drv_list', type: 'array', value: ['default'],
> -       choices: ['alsa', 'coreaudio', 'default', 'dsound', 'jack', 'oss', 'pa', 'sdl', 'sndio'],
> +       choices: ['alsa', 'coreaudio', 'default', 'dsound', 'jack', 'oss', 'pa', 'pipewire', 'sdl', 'sndio'],
>          description: 'Set audio driver list')
>   option('block_drv_rw_whitelist', type : 'string', value : '',
>          description: 'set block driver read-write whitelist (by default affects only QEMU, not tools like qemu-img)')
> @@ -255,6 +255,8 @@ option('oss', type: 'feature', value: 'auto',
>          description: 'OSS sound support')
>   option('pa', type: 'feature', value: 'auto',
>          description: 'PulseAudio sound support')
> +option('pipewire', type: 'feature', value: 'auto',
> +       description: 'Pipewire sound support')
>   option('sndio', type: 'feature', value: 'auto',
>          description: 'sndio sound support')
>   
> diff --git a/qapi/audio.json b/qapi/audio.json
> index 4e54c00f51..e03396a7bc 100644
> --- a/qapi/audio.json
> +++ b/qapi/audio.json
> @@ -324,6 +324,47 @@
>       '*out':    'AudiodevPaPerDirectionOptions',
>       '*server': 'str' } }
>   
> +##
> +# @AudiodevPipewirePerDirectionOptions:
> +#
> +# Options of the Pipewire backend that are used for both playback and
> +# recording.
> +#
> +# @name: name of the sink/source to use
> +#
> +# @stream-name: name of the Pipewire stream created by qemu.  Can be
> +#               used to identify the stream in Pipewire when you
> +#               create multiple Pipewire devices or run multiple qemu
> +#               instances (default: audiodev's id)
> +#
> +# @latency: latency you want Pipewire to achieve in microseconds
> +#           (default 46000)
> +#
> +# Since: 8.1
> +##
> +{ 'struct': 'AudiodevPipewirePerDirectionOptions',
> +  'base': 'AudiodevPerDirectionOptions',
> +  'data': {
> +    '*name': 'str',
> +    '*stream-name': 'str',
> +    '*latency': 'uint32' } }
> +
> +##
> +# @AudiodevPipewireOptions:
> +#
> +# Options of the Pipewire audio backend.
> +#
> +# @in: options of the capture stream
> +#
> +# @out: options of the playback stream
> +#
> +# Since: 8.1
> +##
> +{ 'struct': 'AudiodevPipewireOptions',
> +  'data': {
> +    '*in':     'AudiodevPipewirePerDirectionOptions',
> +    '*out':    'AudiodevPipewirePerDirectionOptions' } }
> +
>   ##
>   # @AudiodevSdlPerDirectionOptions:
>   #
> @@ -416,6 +457,7 @@
>               { 'name': 'jack', 'if': 'CONFIG_AUDIO_JACK' },
>               { 'name': 'oss', 'if': 'CONFIG_AUDIO_OSS' },
>               { 'name': 'pa', 'if': 'CONFIG_AUDIO_PA' },
> +            { 'name': 'pipewire', 'if': 'CONFIG_AUDIO_PIPEWIRE' },
>               { 'name': 'sdl', 'if': 'CONFIG_AUDIO_SDL' },
>               { 'name': 'sndio', 'if': 'CONFIG_AUDIO_SNDIO' },
>               { 'name': 'spice', 'if': 'CONFIG_SPICE' },
> @@ -456,6 +498,8 @@
>                      'if': 'CONFIG_AUDIO_OSS' },
>       'pa':        { 'type': 'AudiodevPaOptions',
>                      'if': 'CONFIG_AUDIO_PA' },
> +    'pipewire':  { 'type': 'AudiodevPipewireOptions',
> +                   'if': 'CONFIG_AUDIO_PIPEWIRE' },
>       'sdl':       { 'type': 'AudiodevSdlOptions',
>                      'if': 'CONFIG_AUDIO_SDL' },
>       'sndio':     { 'type': 'AudiodevSndioOptions',
> diff --git a/qemu-options.hx b/qemu-options.hx
> index 59bdf67a2c..2d908717bd 100644
> --- a/qemu-options.hx
> +++ b/qemu-options.hx
> @@ -779,6 +779,12 @@ DEF("audiodev", HAS_ARG, QEMU_OPTION_audiodev,
>       "                in|out.name= source/sink device name\n"
>       "                in|out.latency= desired latency in microseconds\n"
>   #endif
> +#ifdef CONFIG_AUDIO_PIPEWIRE
> +    "-audiodev pipewire,id=id[,prop[=value][,...]]\n"
> +    "                in|out.name= source/sink device name\n"
> +    "                in|out.stream-name= name of pipewire stream\n"
> +    "                in|out.latency= desired latency in microseconds\n"
> +#endif
>   #ifdef CONFIG_AUDIO_SDL
>       "-audiodev sdl,id=id[,prop[=value][,...]]\n"
>       "                in|out.buffer-count= number of buffers\n"
> @@ -942,6 +948,21 @@ SRST
>           Desired latency in microseconds. The PulseAudio server will try
>           to honor this value but actual latencies may be lower or higher.
>   
> +``-audiodev pipewire,id=id[,prop[=value][,...]]``
> +    Creates a backend using Pipewire. This backend is available on
> +    most systems.
> +
> +    Pipewire specific options are:
> +
> +    ``in|out.latency=usecs``
> +        Desired latency in microseconds.
> +
> +    ``in|out.name=sink``
> +        Use the specified source/sink for recording/playback.
> +
> +    ``in|out.stream-name``
> +        Specify the name of pipewire stream.
> +
>   ``-audiodev sdl,id=id[,prop[=value][,...]]``
>       Creates a backend using SDL. This backend is available on most
>       systems, but you should use your platform's native backend if
> diff --git a/scripts/meson-buildoptions.sh b/scripts/meson-buildoptions.sh
> index 009fab1515..ba1057b62c 100644
> --- a/scripts/meson-buildoptions.sh
> +++ b/scripts/meson-buildoptions.sh
> @@ -1,7 +1,8 @@
>   # This file is generated by meson-buildoptions.py, do not edit!
>   meson_options_help() {
> -  printf "%s\n" '  --audio-drv-list=CHOICES Set audio driver list [default] (choices: alsa/co'
> -  printf "%s\n" '                           reaudio/default/dsound/jack/oss/pa/sdl/sndio)'
> +  printf "%s\n" '  --audio-drv-list=CHOICES Set audio driver list [default] (choices: al'
> +  printf "%s\n" '                           sa/coreaudio/default/dsound/jack/oss/pa/'
> +  printf "%s\n" '                           pipewire/sdl/sndio)'
>     printf "%s\n" '  --block-drv-ro-whitelist=VALUE'
>     printf "%s\n" '                           set block driver read-only whitelist (by default'
>     printf "%s\n" '                           affects only QEMU, not tools like qemu-img)'
> @@ -136,6 +137,7 @@ meson_options_help() {
>     printf "%s\n" '  oss             OSS sound support'
>     printf "%s\n" '  pa              PulseAudio sound support'
>     printf "%s\n" '  parallels       parallels image format support'
> +  printf "%s\n" '  pipewire        Pipewire sound support'
>     printf "%s\n" '  png             PNG support with libpng'
>     printf "%s\n" '  pvrdma          Enable PVRDMA support'
>     printf "%s\n" '  qcow1           qcow1 image format support'
> @@ -370,6 +372,8 @@ _meson_option_parse() {
>       --disable-pa) printf "%s" -Dpa=disabled ;;
>       --enable-parallels) printf "%s" -Dparallels=enabled ;;
>       --disable-parallels) printf "%s" -Dparallels=disabled ;;
> +    --enable-pipewire) printf "%s" -Dpipewire=enabled ;;
> +    --disable-pipewire) printf "%s" -Dpipewire=disabled ;;
>       --with-pkgversion=*) quote_sh "-Dpkgversion=$2" ;;
>       --enable-png) printf "%s" -Dpng=enabled ;;
>       --disable-png) printf "%s" -Dpng=disabled ;;
Re: [PATCH v9] audio/pwaudio.c: Add Pipewire audio backend for QEMU
Posted by Marc-André Lureau 1 year ago
Hi Dorinda,

On Tue, Mar 28, 2023 at 5:08 PM Dorinda Bassey <dbassey@redhat.com> wrote:
>
> This commit adds a new audiodev backend to allow QEMU to use Pipewire as
> both an audio sink and source. This backend is available on most systems
>
> Add Pipewire entry points for QEMU Pipewire audio backend
> Add wrappers for QEMU Pipewire audio backend in qpw_pcm_ops()
> qpw_write function returns the current state of the stream to pwaudio
> and Writes some data to the server for playback streams using pipewire
> spa_ringbuffer implementation.
> qpw_read function returns the current state of the stream to pwaudio and
> reads some data from the server for capture streams using pipewire
> spa_ringbuffer implementation. These functions qpw_write and qpw_read
> are called during playback and capture.
> Added some functions that convert pw audio formats to QEMU audio format
> and vice versa which would be needed in the pipewire audio sink and
> source functions qpw_init_in() & qpw_init_out().
> These methods that implement playback and recording will create streams
> for playback and capture that will start processing and will result in
> the on_process callbacks to be called.
> Built a connection to the Pipewire sound system server in the
> qpw_audio_init() method.
>
> Signed-off-by: Dorinda Bassey <dbassey@redhat.com>
> ---
> v9:
> add code to play silence on a buffer underrun
> remove redundant block in playback and capture process functions
> refactor code for enabling/disabling audio stream
> add volume_out and volume_in pcm_ops function
> add code for in|out.name options
> add in|out.stream-name options
> fix format specifiers
> change release version
> add missing latency option
>
>  audio/audio.c                 |   3 +
>  audio/audio_template.h        |   4 +
>  audio/meson.build             |   1 +
>  audio/pwaudio.c               | 879 ++++++++++++++++++++++++++++++++++
>  audio/trace-events            |   8 +
>  meson.build                   |   8 +
>  meson_options.txt             |   4 +-
>  qapi/audio.json               |  44 ++
>  qemu-options.hx               |  21 +
>  scripts/meson-buildoptions.sh |   8 +-
>  10 files changed, 977 insertions(+), 3 deletions(-)
>  create mode 100644 audio/pwaudio.c
>
> diff --git a/audio/audio.c b/audio/audio.c
> index 70b096713c..90c7c49d11 100644
> --- a/audio/audio.c
> +++ b/audio/audio.c
> @@ -2061,6 +2061,9 @@ void audio_create_pdos(Audiodev *dev)
>  #ifdef CONFIG_AUDIO_PA
>          CASE(PA, pa, Pa);
>  #endif
> +#ifdef CONFIG_AUDIO_PIPEWIRE
> +        CASE(PIPEWIRE, pipewire, Pipewire);
> +#endif
>  #ifdef CONFIG_AUDIO_SDL
>          CASE(SDL, sdl, Sdl);
>  #endif
> diff --git a/audio/audio_template.h b/audio/audio_template.h
> index e42326c20d..dc0c74aa74 100644
> --- a/audio/audio_template.h
> +++ b/audio/audio_template.h
> @@ -362,6 +362,10 @@ AudiodevPerDirectionOptions *glue(audio_get_pdo_, TYPE)(Audiodev *dev)
>      case AUDIODEV_DRIVER_PA:
>          return qapi_AudiodevPaPerDirectionOptions_base(dev->u.pa.TYPE);
>  #endif
> +#ifdef CONFIG_AUDIO_PIPEWIRE
> +    case AUDIODEV_DRIVER_PIPEWIRE:
> +        return qapi_AudiodevPipewirePerDirectionOptions_base(dev->u.pipewire.TYPE);
> +#endif
>  #ifdef CONFIG_AUDIO_SDL
>      case AUDIODEV_DRIVER_SDL:
>          return qapi_AudiodevSdlPerDirectionOptions_base(dev->u.sdl.TYPE);
> diff --git a/audio/meson.build b/audio/meson.build
> index 0722224ba9..65a49c1a10 100644
> --- a/audio/meson.build
> +++ b/audio/meson.build
> @@ -19,6 +19,7 @@ foreach m : [
>    ['sdl', sdl, files('sdlaudio.c')],
>    ['jack', jack, files('jackaudio.c')],
>    ['sndio', sndio, files('sndioaudio.c')],
> +  ['pipewire', pipewire, files('pwaudio.c')],
>    ['spice', spice, files('spiceaudio.c')]
>  ]
>    if m[1].found()
> diff --git a/audio/pwaudio.c b/audio/pwaudio.c
> new file mode 100644
> index 0000000000..ca83bc55f9
> --- /dev/null
> +++ b/audio/pwaudio.c
> @@ -0,0 +1,879 @@
> +/*
> + * QEMU Pipewire audio driver
> + *
> + * Copyright (c) 2023 Red Hat Inc.
> + *
> + * Author: Dorinda Bassey       <dbassey@redhat.com>
> + *
> + * SPDX-License-Identifier: GPL-2.0-or-later
> + */
> +
> +#include "qemu/osdep.h"
> +#include "qemu/module.h"
> +#include "audio.h"
> +#include <errno.h>
> +#include "qemu/error-report.h"
> +#include <spa/param/audio/format-utils.h>
> +#include <spa/utils/ringbuffer.h>
> +#include <spa/utils/result.h>
> +#include <spa/param/props.h>
> +
> +#include <pipewire/pipewire.h>
> +#include "trace.h"
> +
> +#define AUDIO_CAP "pipewire"
> +#define RINGBUFFER_SIZE    (1u << 22)
> +#define RINGBUFFER_MASK    (RINGBUFFER_SIZE - 1)
> +
> +#include "audio_int.h"
> +
> +enum {
> +    MODE_SINK,
> +    MODE_SOURCE
> +};
> +
> +typedef struct pwvolume {
> +    uint32_t channels;
> +    float values[SPA_AUDIO_MAX_CHANNELS];
> +} pwvolume;
> +
> +typedef struct pwaudio {
> +    Audiodev *dev;
> +    struct pw_thread_loop *thread_loop;
> +    struct pw_context *context;
> +
> +    struct pw_core *core;
> +    struct spa_hook core_listener;
> +    int seq;
> +} pwaudio;
> +
> +typedef struct PWVoice {
> +    pwaudio *g;
> +    struct pw_stream *stream;
> +    struct spa_hook stream_listener;
> +    struct spa_audio_info_raw info;
> +    uint32_t highwater_mark;
> +    uint32_t frame_size;
> +    struct spa_ringbuffer ring;
> +    uint8_t buffer[RINGBUFFER_SIZE];
> +
> +    uint32_t mode;
> +    struct pw_properties *props;
> +    pwvolume volume;
> +    bool muted;
> +} PWVoice;
> +
> +typedef struct PWVoiceOut {
> +    HWVoiceOut hw;
> +    PWVoice v;
> +} PWVoiceOut;
> +
> +typedef struct PWVoiceIn {
> +    HWVoiceIn hw;
> +    PWVoice v;
> +} PWVoiceIn;
> +
> +static void
> +stream_destroy(void *data)
> +{
> +    PWVoice *v = (PWVoice *) data;
> +    spa_hook_remove(&v->stream_listener);
> +    v->stream = NULL;
> +}
> +
> +/* output data processing function to read stuffs from the buffer */
> +static void
> +playback_on_process(void *data)
> +{
> +    PWVoice *v = (PWVoice *) data;
> +    void *p;
> +    struct pw_buffer *b;
> +    struct spa_buffer *buf;
> +    uint32_t req, index, n_bytes;
> +    int32_t avail;
> +
> +    if (!v->stream) {
> +        return;
> +    }

Could you replace with an assert(v->stream) instead?


> +
> +    /* obtain a buffer to read from */
> +    b = pw_stream_dequeue_buffer(v->stream);
> +    if (b == NULL) {
> +        error_report("out of buffers: %s", strerror(errno));
> +        return;
> +    }
> +
> +    buf = b->buffer;
> +    p = buf->datas[0].data;
> +    if (p == NULL) {
> +        return;
> +    }
> +    /* calculate the total no of bytes to read data from buffer */
> +    req = b->requested * v->frame_size;
> +    if (req == 0) {
> +        req = (uint64_t)v->g->dev->timer_period * v->info.rate
> +                * 1 / 2 / 1000000 * v->frame_size;
> +    }
> +    n_bytes = SPA_MIN(req, buf->datas[0].maxsize);
> +
> +    /* get no of available bytes to read data from buffer */
> +
> +    avail = spa_ringbuffer_get_read_index(&v->ring, &index);
> +
> +
> +    if (avail == 0) {
> +        memset(p, 0, n_bytes);

Clear the buffer...

> +    }
> +
> +    if (avail < (int32_t) n_bytes) {
> +        n_bytes = avail;

...but queue 0. Look like you don't need the memset() after all.

> +    }
> +
> +    spa_ringbuffer_read_data(&v->ring,
> +                                v->buffer, RINGBUFFER_SIZE,
> +                                index & RINGBUFFER_MASK, p, n_bytes);
> +
> +    index += n_bytes;
> +    spa_ringbuffer_read_update(&v->ring, index);
> +
> +    buf->datas[0].chunk->offset = 0;
> +    buf->datas[0].chunk->stride = v->frame_size;
> +    buf->datas[0].chunk->size = n_bytes;
> +
> +    /* queue the buffer for playback */
> +    pw_stream_queue_buffer(v->stream, b);
> +}
> +
> +/* output data processing function to generate stuffs in the buffer */
> +static void
> +capture_on_process(void *data)
> +{
> +    PWVoice *v = (PWVoice *) data;
> +    void *p;
> +    struct pw_buffer *b;
> +    struct spa_buffer *buf;
> +    int32_t filled;
> +    uint32_t index, offs, n_bytes;
> +
> +    if (!v->stream) {
> +        return;
> +    }

Could you replace with an assert(v->stream) instead?

> +
> +    /* obtain a buffer */
> +    b = pw_stream_dequeue_buffer(v->stream);
> +    if (b == NULL) {
> +        error_report("out of buffers: %s", strerror(errno));
> +        return;
> +    }
> +
> +    /* Write data into buffer */
> +    buf = b->buffer;
> +    p = buf->datas[0].data;
> +    if (p == NULL) {
> +        return;
> +    }
> +    offs = SPA_MIN(buf->datas[0].chunk->offset, buf->datas[0].maxsize);
> +    n_bytes = SPA_MIN(buf->datas[0].chunk->size, buf->datas[0].maxsize - offs);
> +
> +    filled = spa_ringbuffer_get_write_index(&v->ring, &index);
> +
> +
> +    if (filled < 0) {
> +        error_report("%p: underrun write:%u filled:%d", p, index, filled);
> +    } else {
> +        if ((uint32_t) filled + n_bytes > RINGBUFFER_SIZE) {
> +            error_report("%p: overrun write:%u filled:%d + size:%u > max:%u",
> +            p, index, filled, n_bytes, RINGBUFFER_SIZE);
> +        }
> +    }
> +    spa_ringbuffer_write_data(&v->ring,
> +                                v->buffer, RINGBUFFER_SIZE,
> +                                index & RINGBUFFER_MASK,
> +                                SPA_PTROFF(p, offs, void), n_bytes);
> +    index += n_bytes;
> +    spa_ringbuffer_write_update(&v->ring, index);
> +
> +    /* queue the buffer for playback */
> +    pw_stream_queue_buffer(v->stream, b);
> +}
> +
> +static void
> +on_stream_state_changed(void *_data, enum pw_stream_state old,
> +                        enum pw_stream_state state, const char *error)
> +{
> +    PWVoice *v = (PWVoice *) _data;

why not simply name it "data"?

> +
> +    trace_pw_state_changed(pw_stream_state_as_string(state));
> +
> +    switch (state) {
> +    case PW_STREAM_STATE_ERROR:
> +    case PW_STREAM_STATE_UNCONNECTED:
> +        {
> +            break;
> +        }

hmm..

> +    case PW_STREAM_STATE_PAUSED:
> +        trace_pw_node(pw_stream_get_node_id(v->stream));
> +        break;
> +    case PW_STREAM_STATE_CONNECTING:
> +    case PW_STREAM_STATE_STREAMING:
> +        break;
> +    }

I understand it may be desirable to have a trace for stream state
change. But the implementation could be simpler, no switch involved,
and easier to read, simply change the code to:

 trace_pw_state_changed(pw_stream_get_node_id(v->stream),
pw_stream_state_as_string(state));


> +}
> +
> +static const struct pw_stream_events capture_stream_events = {
> +    PW_VERSION_STREAM_EVENTS,
> +    .destroy = stream_destroy,
> +    .state_changed = on_stream_state_changed,
> +    .process = capture_on_process
> +};
> +
> +static const struct pw_stream_events playback_stream_events = {
> +    PW_VERSION_STREAM_EVENTS,
> +    .destroy = stream_destroy,
> +    .state_changed = on_stream_state_changed,
> +    .process = playback_on_process
> +};
> +
> +static size_t
> +qpw_read(HWVoiceIn *hw, void *data, size_t len)
> +{
> +    PWVoiceIn *pw = (PWVoiceIn *) hw;
> +    PWVoice *v = &pw->v;
> +    pwaudio *c = v->g;
> +    const char *error = NULL;
> +    size_t l;
> +    int32_t avail;
> +    uint32_t index;
> +
> +    pw_thread_loop_lock(c->thread_loop);
> +    if (pw_stream_get_state(v->stream, &error) != PW_STREAM_STATE_STREAMING) {
> +        /* wait for stream to become ready */
> +        l = 0;
> +        goto done_unlock;
> +    }
> +    /* get no of available bytes to read data from buffer */
> +    avail = spa_ringbuffer_get_read_index(&v->ring, &index);
> +
> +    trace_pw_read(avail, index, len);
> +
> +    if (avail < (int32_t) len) {
> +        len = avail;
> +    }
> +
> +    spa_ringbuffer_read_data(&v->ring,
> +                             v->buffer, RINGBUFFER_SIZE,
> +                             index & RINGBUFFER_MASK, data, len);
> +    index += len;
> +    spa_ringbuffer_read_update(&v->ring, index);
> +    l = len;
> +
> +done_unlock:
> +    pw_thread_loop_unlock(c->thread_loop);
> +    return l;
> +}
> +
> +static size_t qpw_buffer_get_free(HWVoiceOut *hw)
> +{
> +    PWVoiceOut *pw = (PWVoiceOut *)hw;
> +    PWVoice *v = &pw->v;
> +    pwaudio *c = v->g;
> +    const char *error = NULL;
> +    int32_t filled, avail;
> +    uint32_t index;
> +
> +    pw_thread_loop_lock(c->thread_loop);
> +    if (pw_stream_get_state(v->stream, &error) != PW_STREAM_STATE_STREAMING) {
> +        /* wait for stream to become ready */
> +        avail = 0;
> +        goto done_unlock;
> +    }
> +
> +    filled = spa_ringbuffer_get_write_index(&v->ring, &index);
> +    avail = v->highwater_mark - filled;
> +
> +done_unlock:
> +    pw_thread_loop_unlock(c->thread_loop);
> +    return avail;
> +}
> +
> +static size_t
> +qpw_write(HWVoiceOut *hw, void *data, size_t len)
> +{
> +    PWVoiceOut *pw = (PWVoiceOut *) hw;
> +    PWVoice *v = &pw->v;
> +    pwaudio *c = v->g;
> +    const char *error = NULL;
> +    int32_t filled, avail;
> +    uint32_t index;
> +
> +    pw_thread_loop_lock(c->thread_loop);
> +    if (pw_stream_get_state(v->stream, &error) != PW_STREAM_STATE_STREAMING) {
> +        /* wait for stream to become ready */
> +        len = 0;
> +        goto done_unlock;
> +    }
> +    filled = spa_ringbuffer_get_write_index(&v->ring, &index);
> +    avail = v->highwater_mark - filled;
> +
> +    trace_pw_write(filled, avail, index, len);
> +
> +    if (len > avail) {
> +        len = avail;
> +    }
> +
> +    if (filled < 0) {
> +        error_report("%p: underrun write:%u filled:%d", pw, index, filled);
> +    } else {
> +        if ((uint32_t) filled + len > RINGBUFFER_SIZE) {
> +            error_report("%p: overrun write:%u filled:%d + size:%zu > max:%u",
> +            pw, index, filled, len, RINGBUFFER_SIZE);
> +        }
> +    }
> +
> +    spa_ringbuffer_write_data(&v->ring,
> +                                v->buffer, RINGBUFFER_SIZE,
> +                                index & RINGBUFFER_MASK, data, len);
> +    index += len;
> +    spa_ringbuffer_write_update(&v->ring, index);
> +
> +done_unlock:
> +    pw_thread_loop_unlock(c->thread_loop);
> +    return len;
> +}
> +
> +static int
> +audfmt_to_pw(AudioFormat fmt, int endianness)
> +{
> +    int format;
> +
> +    switch (fmt) {
> +    case AUDIO_FORMAT_S8:
> +        format = SPA_AUDIO_FORMAT_S8;
> +        break;
> +    case AUDIO_FORMAT_U8:
> +        format = SPA_AUDIO_FORMAT_U8;
> +        break;
> +    case AUDIO_FORMAT_S16:
> +        format = endianness ? SPA_AUDIO_FORMAT_S16_BE : SPA_AUDIO_FORMAT_S16_LE;
> +        break;
> +    case AUDIO_FORMAT_U16:
> +        format = endianness ? SPA_AUDIO_FORMAT_U16_BE : SPA_AUDIO_FORMAT_U16_LE;
> +        break;
> +    case AUDIO_FORMAT_S32:
> +        format = endianness ? SPA_AUDIO_FORMAT_S32_BE : SPA_AUDIO_FORMAT_S32_LE;
> +        break;
> +    case AUDIO_FORMAT_U32:
> +        format = endianness ? SPA_AUDIO_FORMAT_U32_BE : SPA_AUDIO_FORMAT_U32_LE;
> +        break;
> +    case AUDIO_FORMAT_F32:
> +        format = endianness ? SPA_AUDIO_FORMAT_F32_BE : SPA_AUDIO_FORMAT_F32_LE;
> +        break;
> +    default:
> +        dolog("Internal logic error: Bad audio format %d\n", fmt);
> +        format = SPA_AUDIO_FORMAT_U8;
> +        break;
> +    }
> +    return format;
> +}
> +
> +static AudioFormat
> +pw_to_audfmt(enum spa_audio_format fmt, int *endianness,
> +             uint32_t *frame_size)
> +{
> +    switch (fmt) {
> +    case SPA_AUDIO_FORMAT_S8:
> +        *frame_size = 1;
> +        return AUDIO_FORMAT_S8;
> +    case SPA_AUDIO_FORMAT_U8:
> +        *frame_size = 1;
> +        return AUDIO_FORMAT_U8;
> +    case SPA_AUDIO_FORMAT_S16_BE:
> +        *frame_size = 2;
> +        *endianness = 1;
> +        return AUDIO_FORMAT_S16;
> +    case SPA_AUDIO_FORMAT_S16_LE:
> +        *frame_size = 2;
> +        *endianness = 0;
> +        return AUDIO_FORMAT_S16;
> +    case SPA_AUDIO_FORMAT_U16_BE:
> +        *frame_size = 2;
> +        *endianness = 1;
> +        return AUDIO_FORMAT_U16;
> +    case SPA_AUDIO_FORMAT_U16_LE:
> +        *frame_size = 2;
> +        *endianness = 0;
> +        return AUDIO_FORMAT_U16;
> +    case SPA_AUDIO_FORMAT_S32_BE:
> +        *frame_size = 4;
> +        *endianness = 1;
> +        return AUDIO_FORMAT_S32;
> +    case SPA_AUDIO_FORMAT_S32_LE:
> +        *frame_size = 4;
> +        *endianness = 0;
> +        return AUDIO_FORMAT_S32;
> +    case SPA_AUDIO_FORMAT_U32_BE:
> +        *frame_size = 4;
> +        *endianness = 1;
> +        return AUDIO_FORMAT_U32;
> +    case SPA_AUDIO_FORMAT_U32_LE:
> +        *frame_size = 4;
> +        *endianness = 0;
> +        return AUDIO_FORMAT_U32;
> +    case SPA_AUDIO_FORMAT_F32_BE:
> +        *frame_size = 4;
> +        *endianness = 1;
> +        return AUDIO_FORMAT_F32;
> +    case SPA_AUDIO_FORMAT_F32_LE:
> +        *frame_size = 4;
> +        *endianness = 0;
> +        return AUDIO_FORMAT_F32;
> +    default:
> +        *frame_size = 1;
> +        dolog("Internal logic error: Bad spa_audio_format %d\n", fmt);
> +        return AUDIO_FORMAT_U8;
> +    }
> +}
> +
> +static int
> +create_stream(pwaudio *c, PWVoice *v, const char *stream_name, const char *name)
> +{
> +    int res;
> +    uint32_t n_params;
> +    const struct spa_pod *params[2];
> +    uint8_t buffer[1024];
> +    struct spa_pod_builder b;
> +
> +    v->props = pw_properties_new(NULL, NULL);
> +    pw_properties_setf(v->props, PW_KEY_NODE_LATENCY, "%" PRIu64 "/%u",
> +                       (uint64_t)v->g->dev->timer_period * v->info.rate
> +                       * 3 / 4 / 1000000, v->info.rate);

What is 3/4 for? I might have missed previous discussions, it would be
worth explaining and adding a trace for the value.

> +    if (name) {
> +        pw_properties_set(v->props, PW_KEY_TARGET_OBJECT, name);
> +    }
> +    v->stream = pw_stream_new(c->core, stream_name, v->props);
> +
> +    if (v->stream == NULL) {
> +        return -1;
> +    }
> +
> +    if (v->mode == MODE_SOURCE) {
> +        pw_stream_add_listener(v->stream,
> +                            &v->stream_listener, &capture_stream_events, v);
> +    } else {
> +        pw_stream_add_listener(v->stream,
> +                            &v->stream_listener, &playback_stream_events, v);
> +    }
> +
> +    n_params = 0;
> +    spa_pod_builder_init(&b, buffer, sizeof(buffer));
> +    params[n_params++] = spa_format_audio_raw_build(&b,
> +                            SPA_PARAM_EnumFormat,
> +                            &v->info);
> +
> +    /* connect the stream to a sink or source */
> +    res = pw_stream_connect(v->stream,
> +                            v->mode ==
> +                            MODE_SOURCE ? PW_DIRECTION_INPUT :
> +                            PW_DIRECTION_OUTPUT, PW_ID_ANY,
> +                            PW_STREAM_FLAG_AUTOCONNECT |
> +                            PW_STREAM_FLAG_INACTIVE |
> +                            PW_STREAM_FLAG_MAP_BUFFERS |
> +                            PW_STREAM_FLAG_RT_PROCESS, params, n_params);
> +    if (res < 0) {
> +        pw_stream_destroy(v->stream);
> +        return -1;
> +    }
> +
> +    return 0;
> +}
> +
> +static int
> +qpw_stream_new(pwaudio *c, PWVoice *v,
> +               const char *stream_name, const char *name)
> +{
> +    int r;
> +
> +    switch (v->info.channels) {
> +    case 8:
> +        v->info.position[0] = SPA_AUDIO_CHANNEL_FL;
> +        v->info.position[1] = SPA_AUDIO_CHANNEL_FR;
> +        v->info.position[2] = SPA_AUDIO_CHANNEL_FC;
> +        v->info.position[3] = SPA_AUDIO_CHANNEL_LFE;
> +        v->info.position[4] = SPA_AUDIO_CHANNEL_RL;
> +        v->info.position[5] = SPA_AUDIO_CHANNEL_RR;
> +        v->info.position[6] = SPA_AUDIO_CHANNEL_SL;
> +        v->info.position[7] = SPA_AUDIO_CHANNEL_SR;
> +        break;
> +    case 6:
> +        v->info.position[0] = SPA_AUDIO_CHANNEL_FL;
> +        v->info.position[1] = SPA_AUDIO_CHANNEL_FR;
> +        v->info.position[2] = SPA_AUDIO_CHANNEL_FC;
> +        v->info.position[3] = SPA_AUDIO_CHANNEL_LFE;
> +        v->info.position[4] = SPA_AUDIO_CHANNEL_RL;
> +        v->info.position[5] = SPA_AUDIO_CHANNEL_RR;
> +        break;
> +    case 5:
> +        v->info.position[0] = SPA_AUDIO_CHANNEL_FL;
> +        v->info.position[1] = SPA_AUDIO_CHANNEL_FR;
> +        v->info.position[2] = SPA_AUDIO_CHANNEL_FC;
> +        v->info.position[3] = SPA_AUDIO_CHANNEL_LFE;
> +        v->info.position[4] = SPA_AUDIO_CHANNEL_RC;
> +        break;
> +    case 4:
> +        v->info.position[0] = SPA_AUDIO_CHANNEL_FL;
> +        v->info.position[1] = SPA_AUDIO_CHANNEL_FR;
> +        v->info.position[2] = SPA_AUDIO_CHANNEL_FC;
> +        v->info.position[3] = SPA_AUDIO_CHANNEL_RC;
> +        break;
> +    case 3:
> +        v->info.position[0] = SPA_AUDIO_CHANNEL_FL;
> +        v->info.position[1] = SPA_AUDIO_CHANNEL_FR;
> +        v->info.position[2] = SPA_AUDIO_CHANNEL_LFE;
> +        break;
> +    case 2:
> +        v->info.position[0] = SPA_AUDIO_CHANNEL_FL;
> +        v->info.position[1] = SPA_AUDIO_CHANNEL_FR;
> +        break;
> +    case 1:
> +        v->info.position[0] = SPA_AUDIO_CHANNEL_MONO;
> +        break;
> +    default:
> +        for (size_t i = 0; i < v->info.channels; i++) {
> +            v->info.position[i] = SPA_AUDIO_CHANNEL_UNKNOWN;
> +        }
> +        break;
> +    }
> +
> +    /* create a new unconnected pwstream */
> +    r = create_stream(c, v, stream_name, name);
> +    if (r < 0) {
> +        AUD_log(AUDIO_CAP, "Failed to create stream.");
> +        return -1;
> +    }
> +
> +    return r;
> +}
> +
> +static int
> +qpw_init_out(HWVoiceOut *hw, struct audsettings *as, void *drv_opaque)
> +{
> +    PWVoiceOut *pw = (PWVoiceOut *) hw;
> +    PWVoice *v = &pw->v;
> +    struct audsettings obt_as = *as;
> +    pwaudio *c = v->g = drv_opaque;
> +    AudiodevPipewireOptions *popts = &c->dev->u.pipewire;
> +    AudiodevPipewirePerDirectionOptions *ppdo = popts->out;
> +    int r;
> +
> +    v->mode = MODE_SINK;

This field and enum is not necessary if you simply pass a PW_DIRECTION
down to create_stream().

> +
> +    pw_thread_loop_lock(c->thread_loop);
> +
> +    v->info.format = audfmt_to_pw(as->fmt, as->endianness);
> +    v->info.channels = as->nchannels;
> +    v->info.rate = as->freq;
> +
> +    obt_as.fmt =
> +        pw_to_audfmt(v->info.format, &obt_as.endianness, &v->frame_size);
> +    v->frame_size *= as->nchannels;
> +
> +    /* call the function that creates a new stream for playback */
> +    r = qpw_stream_new(c, v, ppdo->stream_name ? : c->dev->id, ppdo->name);
> +    if (r < 0) {
> +        error_report("qpw_stream_new for playback failed");
> +        pw_thread_loop_unlock(c->thread_loop);
> +        return -1;
> +    }
> +
> +    /* report the audio format we support */
> +    audio_pcm_init_info(&hw->info, &obt_as);
> +
> +    /* report the buffer size to qemu */
> +    hw->samples = audio_buffer_frames(
> +        qapi_AudiodevPipewirePerDirectionOptions_base(ppdo), &obt_as, 46440);
> +    v->highwater_mark = MIN(RINGBUFFER_SIZE,
> +                            (ppdo->has_latency ? ppdo->latency : 46440)
> +                            * (uint64_t)v->info.rate / 1000000 * v->frame_size);
> +
> +    pw_thread_loop_unlock(c->thread_loop);
> +    return 0;
> +}
> +
> +static int
> +qpw_init_in(HWVoiceIn *hw, struct audsettings *as, void *drv_opaque)
> +{
> +    PWVoiceIn *pw = (PWVoiceIn *) hw;
> +    PWVoice *v = &pw->v;
> +    struct audsettings obt_as = *as;
> +    pwaudio *c = v->g = drv_opaque;
> +    AudiodevPipewireOptions *popts = &c->dev->u.pipewire;
> +    AudiodevPipewirePerDirectionOptions *ppdo = popts->in;
> +    int r;
> +
> +    v->mode = MODE_SOURCE;
> +    pw_thread_loop_lock(c->thread_loop);
> +
> +    v->info.format = audfmt_to_pw(as->fmt, as->endianness);
> +    v->info.channels = as->nchannels;
> +    v->info.rate = as->freq;
> +
> +    obt_as.fmt =
> +        pw_to_audfmt(v->info.format, &obt_as.endianness, &v->frame_size);
> +    v->frame_size *= as->nchannels;
> +
> +    /* call the function that creates a new stream for recording */
> +    r = qpw_stream_new(c, v, ppdo->stream_name ? : c->dev->id, ppdo->name);
> +    if (r < 0) {
> +        error_report("qpw_stream_new for recording failed");
> +        pw_thread_loop_unlock(c->thread_loop);
> +        return -1;
> +    }
> +
> +    /* report the audio format we support */
> +    audio_pcm_init_info(&hw->info, &obt_as);
> +
> +    /* report the buffer size to qemu */
> +    hw->samples = audio_buffer_frames(
> +        qapi_AudiodevPipewirePerDirectionOptions_base(ppdo), &obt_as, 46440);
> +
> +    pw_thread_loop_unlock(c->thread_loop);
> +    return 0;
> +}
> +
> +static void
> +qpw_fini_out(HWVoiceOut *hw)
> +{
> +    PWVoiceOut *pw = (PWVoiceOut *) hw;
> +    PWVoice *v = &pw->v;
> +
> +    if (v->stream) {
> +        pwaudio *c = v->g;
> +        pw_thread_loop_lock(c->thread_loop);
> +        pw_stream_destroy(v->stream);
> +        v->stream = NULL;
> +        pw_thread_loop_unlock(c->thread_loop);
> +    }
> +}
> +
> +static void
> +qpw_fini_in(HWVoiceIn *hw)
> +{
> +    PWVoiceIn *pw = (PWVoiceIn *) hw;
> +    PWVoice *v = &pw->v;
> +
> +    if (v->stream) {
> +        pwaudio *c = v->g;
> +        pw_thread_loop_lock(c->thread_loop);
> +        pw_stream_destroy(v->stream);
> +        v->stream = NULL;
> +        pw_thread_loop_unlock(c->thread_loop);
> +    }
> +}

It looks like you could easily factorize the 2 functions (an extra
function with PWVoice argument).

> +
> +static void
> +qpw_enable_out(HWVoiceOut *hw, bool enable)
> +{
> +    PWVoiceOut *po = (PWVoiceOut *) hw;
> +    PWVoice *v = &po->v;
> +    pw_stream_set_active(v->stream, enable);
> +}
> +
> +static void
> +qpw_enable_in(HWVoiceIn *hw, bool enable)
> +{
> +    PWVoiceIn *pi = (PWVoiceIn *) hw;
> +    PWVoice *v = &pi->v;
> +    pw_stream_set_active(v->stream, enable);
> +}
> +
> +static void
> +qpw_volume_out(HWVoiceOut *hw, Volume *vol)
> +{
> +    PWVoiceOut *pw = (PWVoiceOut *) hw;
> +    PWVoice *v = &pw->v;
> +    pwaudio *c = v->g;
> +    int i, ret;
> +
> +    pw_thread_loop_lock(c->thread_loop);
> +    v->volume.channels = vol->channels;
> +
> +    for (i = 0; i < vol->channels; ++i) {
> +        v->volume.values[i] = vol->vol[i] / 100;
> +    }
> +
> +    ret = pw_stream_set_control(v->stream,
> +        SPA_PROP_channelVolumes, v->volume.channels, v->volume.values, 0);
> +    trace_pw_vol(ret == 0 ? "success" : "failed");
> +
> +    v->muted = vol->mute;
> +    float val = v->muted ? 1.f : 0.f;
> +    ret = pw_stream_set_control(v->stream, SPA_PROP_mute, 1, &val, 0);
> +    pw_thread_loop_unlock(c->thread_loop);
> +}
> +
> +static void
> +qpw_volume_in(HWVoiceIn *hw, Volume *vol)
> +{
> +    PWVoiceIn *pw = (PWVoiceIn *) hw;
> +    PWVoice *v = &pw->v;
> +    pwaudio *c = v->g;
> +    int i, ret;
> +
> +    pw_thread_loop_lock(c->thread_loop);
> +    v->volume.channels = vol->channels;
> +
> +    for (i = 0; i < vol->channels; ++i) {
> +        v->volume.values[i] = vol->vol[i] / 100;
> +    }
> +
> +    ret = pw_stream_set_control(v->stream,
> +        SPA_PROP_channelVolumes, v->volume.channels, v->volume.values, 0);
> +    trace_pw_vol(ret == 0 ? "success" : "failed");
> +
> +    v->muted = vol->mute;
> +    float val = v->muted ? 1.f : 0.f;
> +    ret = pw_stream_set_control(v->stream, SPA_PROP_mute, 1, &val, 0);
> +    pw_thread_loop_unlock(c->thread_loop);
> +}

It looks like you could easily factorize the 2 functions.

> +
> +static void
> +on_core_error(void *data, uint32_t id, int seq, int res, const char *message)
> +{
> +    pwaudio *pw = data;
> +
> +    error_report("error id:%u seq:%d res:%d (%s): %s",
> +                id, seq, res, spa_strerror(res), message);
> +
> +    /* stop and exit the thread loop */
> +    pw_thread_loop_signal(pw->thread_loop, FALSE);

I don't understand how this works. The API doc says:
"Signal the thread of loop. If wait_for_accept is true, this function
waits until pw_thread_loop_accept() is called."

And, the associated waiting function is pw_thread_loop_wait(). Can you
explain where it is called from? (since it's not in this file)

> +}
> +
> +static void
> +on_core_done(void *data, uint32_t id, int seq)
> +{
> +    pwaudio *pw = data;
> +    if (id == PW_ID_CORE) {
> +        pw->seq = seq;
> +        /* stop and exit the thread loop */
> +        pw_thread_loop_signal(pw->thread_loop, FALSE);

(same remark about signal)



What do you need pw->seq for?

> +    }
> +}
> +
> +static const struct pw_core_events core_events = {
> +    PW_VERSION_CORE_EVENTS,
> +    .done = on_core_done,
> +    .error = on_core_error,
> +};
> +
> +static void *
> +qpw_audio_init(Audiodev *dev)
> +{
> +    g_autofree pwaudio *pw = g_new0(pwaudio, 1);
> +    pw_init(NULL, NULL);
> +
> +    trace_pw_audio_init();
> +    assert(dev->driver == AUDIODEV_DRIVER_PIPEWIRE);
> +
> +    pw->dev = dev;
> +    pw->thread_loop = pw_thread_loop_new("Pipewire thread loop", NULL);
> +    if (pw->thread_loop == NULL) {
> +        error_report("Could not create Pipewire loop");
> +        goto fail;
> +    }
> +
> +    pw->context =
> +        pw_context_new(pw_thread_loop_get_loop(pw->thread_loop), NULL, 0);
> +    if (pw->context == NULL) {
> +        error_report("Could not create Pipewire context");
> +        goto fail;
> +    }
> +
> +    if (pw_thread_loop_start(pw->thread_loop) < 0) {
> +        error_report("Could not start Pipewire loop");
> +        goto fail;
> +    }
> +
> +    pw_thread_loop_lock(pw->thread_loop);
> +
> +    pw->core = pw_context_connect(pw->context, NULL, 0);
> +    if (pw->core == NULL) {
> +        pw_thread_loop_unlock(pw->thread_loop);
> +        goto fail;
> +    }
> +
> +    pw_core_add_listener(pw->core, &pw->core_listener, &core_events, pw);
> +
> +    pw_thread_loop_unlock(pw->thread_loop);
> +
> +    return g_steal_pointer(&pw);
> +
> +fail:
> +    AUD_log(AUDIO_CAP, "Failed to initialize PW context");
> +    if (pw->thread_loop) {
> +        pw_thread_loop_stop(pw->thread_loop);
> +        g_clear_pointer(&pw->thread_loop, pw_thread_loop_destroy);
> +    }
> +    if (pw->context) {
> +        g_clear_pointer(&pw->context, pw_context_destroy);
> +    }

You should clean up in reverse order of initialization, no?

> +    return NULL;
> +}
> +
> +static void
> +qpw_audio_fini(void *opaque)
> +{
> +    pwaudio *pw = opaque;
> +
> +    pw_thread_loop_stop(pw->thread_loop);

No lock needed?

Are you sure stopping the loop before ending the core and the context
associated with it here is fine?


> +
> +    if (pw->core) {
> +        spa_hook_remove(&pw->core_listener);
> +        spa_zero(pw->core_listener);
> +        pw_core_disconnect(pw->core);
> +    }
> +
> +    if (pw->context) {
> +        pw_context_destroy(pw->context);
> +    }
> +    pw_thread_loop_destroy(pw->thread_loop);
> +
> +    g_free(pw);
> +}
> +
> +static struct audio_pcm_ops qpw_pcm_ops = {
> +    .init_out = qpw_init_out,
> +    .fini_out = qpw_fini_out,
> +    .write = qpw_write,
> +    .buffer_get_free = qpw_buffer_get_free,
> +    .run_buffer_out = audio_generic_run_buffer_out,
> +    .enable_out = qpw_enable_out,
> +    .volume_out = qpw_volume_out,
> +    .volume_in = qpw_volume_in,
> +
> +    .init_in = qpw_init_in,
> +    .fini_in = qpw_fini_in,
> +    .read = qpw_read,
> +    .run_buffer_in = audio_generic_run_buffer_in,
> +    .enable_in = qpw_enable_in
> +};
> +
> +static struct audio_driver pw_audio_driver = {
> +    .name = "pipewire",
> +    .descr = "http://www.pipewire.org/",
> +    .init = qpw_audio_init,
> +    .fini = qpw_audio_fini,
> +    .pcm_ops = &qpw_pcm_ops,
> +    .can_be_default = 1,
> +    .max_voices_out = INT_MAX,
> +    .max_voices_in = INT_MAX,
> +    .voice_size_out = sizeof(PWVoiceOut),
> +    .voice_size_in = sizeof(PWVoiceIn),
> +};
> +
> +static void
> +register_audio_pw(void)
> +{
> +    audio_driver_register(&pw_audio_driver);
> +}
> +
> +type_init(register_audio_pw);
> diff --git a/audio/trace-events b/audio/trace-events
> index e1ab643add..59ec817c9d 100644
> --- a/audio/trace-events
> +++ b/audio/trace-events
> @@ -18,6 +18,14 @@ dbus_audio_register(const char *s, const char *dir) "sender = %s, dir = %s"
>  dbus_audio_put_buffer_out(size_t len) "len = %zu"
>  dbus_audio_read(size_t len) "len = %zu"
>
> +# pwaudio.c
> +pw_state_changed(const char *s) "stream state: %s"
> +pw_node(int nodeid) "node id: %d"
> +pw_read(int32_t avail, uint32_t index, size_t len) "avail=%d index=%u len=%zu"
> +pw_write(int32_t filled, int32_t avail, uint32_t index, size_t len) "filled=%d avail=%d index=%u len=%zu"
> +pw_vol(const char *ret) "set volume: %s"
> +pw_audio_init(void) "Initialize Pipewire context"
> +
>  # audio.c
>  audio_timer_start(int interval) "interval %d ms"
>  audio_timer_stop(void) ""
> diff --git a/meson.build b/meson.build
> index 29f8644d6d..31bf280c0d 100644
> --- a/meson.build
> +++ b/meson.build
> @@ -730,6 +730,12 @@ if not get_option('jack').auto() or have_system
>    jack = dependency('jack', required: get_option('jack'),
>                      method: 'pkg-config', kwargs: static_kwargs)
>  endif
> +pipewire = not_found
> +if not get_option('pipewire').auto() or (targetos == 'linux' and have_system)
> +  pipewire = dependency('libpipewire-0.3', version: '>=0.3.60',
> +                    required: get_option('pipewire'),
> +                    method: 'pkg-config', kwargs: static_kwargs)
> +endif
>  sndio = not_found
>  if not get_option('sndio').auto() or have_system
>    sndio = dependency('sndio', required: get_option('sndio'),
> @@ -1667,6 +1673,7 @@ if have_system
>      'jack': jack.found(),
>      'oss': oss.found(),
>      'pa': pulse.found(),
> +    'pipewire': pipewire.found(),
>      'sdl': sdl.found(),
>      'sndio': sndio.found(),
>    }
> @@ -3980,6 +3987,7 @@ if targetos == 'linux'
>    summary_info += {'ALSA support':    alsa}
>    summary_info += {'PulseAudio support': pulse}
>  endif
> +summary_info += {'Pipewire support':   pipewire}
>  summary_info += {'JACK support':      jack}
>  summary_info += {'brlapi support':    brlapi}
>  summary_info += {'vde support':       vde}
> diff --git a/meson_options.txt b/meson_options.txt
> index fc9447d267..9ae1ec7f47 100644
> --- a/meson_options.txt
> +++ b/meson_options.txt
> @@ -21,7 +21,7 @@ option('tls_priority', type : 'string', value : 'NORMAL',
>  option('default_devices', type : 'boolean', value : true,
>         description: 'Include a default selection of devices in emulators')
>  option('audio_drv_list', type: 'array', value: ['default'],
> -       choices: ['alsa', 'coreaudio', 'default', 'dsound', 'jack', 'oss', 'pa', 'sdl', 'sndio'],
> +       choices: ['alsa', 'coreaudio', 'default', 'dsound', 'jack', 'oss', 'pa', 'pipewire', 'sdl', 'sndio'],
>         description: 'Set audio driver list')
>  option('block_drv_rw_whitelist', type : 'string', value : '',
>         description: 'set block driver read-write whitelist (by default affects only QEMU, not tools like qemu-img)')
> @@ -255,6 +255,8 @@ option('oss', type: 'feature', value: 'auto',
>         description: 'OSS sound support')
>  option('pa', type: 'feature', value: 'auto',
>         description: 'PulseAudio sound support')
> +option('pipewire', type: 'feature', value: 'auto',
> +       description: 'Pipewire sound support')
>  option('sndio', type: 'feature', value: 'auto',
>         description: 'sndio sound support')
>
> diff --git a/qapi/audio.json b/qapi/audio.json
> index 4e54c00f51..e03396a7bc 100644
> --- a/qapi/audio.json
> +++ b/qapi/audio.json
> @@ -324,6 +324,47 @@
>      '*out':    'AudiodevPaPerDirectionOptions',
>      '*server': 'str' } }
>
> +##
> +# @AudiodevPipewirePerDirectionOptions:
> +#
> +# Options of the Pipewire backend that are used for both playback and
> +# recording.
> +#
> +# @name: name of the sink/source to use
> +#
> +# @stream-name: name of the Pipewire stream created by qemu.  Can be
> +#               used to identify the stream in Pipewire when you
> +#               create multiple Pipewire devices or run multiple qemu
> +#               instances (default: audiodev's id)
> +#
> +# @latency: latency you want Pipewire to achieve in microseconds
> +#           (default 46000)
> +#
> +# Since: 8.1
> +##
> +{ 'struct': 'AudiodevPipewirePerDirectionOptions',
> +  'base': 'AudiodevPerDirectionOptions',
> +  'data': {
> +    '*name': 'str',
> +    '*stream-name': 'str',
> +    '*latency': 'uint32' } }
> +
> +##
> +# @AudiodevPipewireOptions:
> +#
> +# Options of the Pipewire audio backend.
> +#
> +# @in: options of the capture stream
> +#
> +# @out: options of the playback stream
> +#
> +# Since: 8.1
> +##
> +{ 'struct': 'AudiodevPipewireOptions',
> +  'data': {
> +    '*in':     'AudiodevPipewirePerDirectionOptions',
> +    '*out':    'AudiodevPipewirePerDirectionOptions' } }
> +
>  ##
>  # @AudiodevSdlPerDirectionOptions:
>  #
> @@ -416,6 +457,7 @@
>              { 'name': 'jack', 'if': 'CONFIG_AUDIO_JACK' },
>              { 'name': 'oss', 'if': 'CONFIG_AUDIO_OSS' },
>              { 'name': 'pa', 'if': 'CONFIG_AUDIO_PA' },
> +            { 'name': 'pipewire', 'if': 'CONFIG_AUDIO_PIPEWIRE' },
>              { 'name': 'sdl', 'if': 'CONFIG_AUDIO_SDL' },
>              { 'name': 'sndio', 'if': 'CONFIG_AUDIO_SNDIO' },
>              { 'name': 'spice', 'if': 'CONFIG_SPICE' },
> @@ -456,6 +498,8 @@
>                     'if': 'CONFIG_AUDIO_OSS' },
>      'pa':        { 'type': 'AudiodevPaOptions',
>                     'if': 'CONFIG_AUDIO_PA' },
> +    'pipewire':  { 'type': 'AudiodevPipewireOptions',
> +                   'if': 'CONFIG_AUDIO_PIPEWIRE' },
>      'sdl':       { 'type': 'AudiodevSdlOptions',
>                     'if': 'CONFIG_AUDIO_SDL' },
>      'sndio':     { 'type': 'AudiodevSndioOptions',
> diff --git a/qemu-options.hx b/qemu-options.hx
> index 59bdf67a2c..2d908717bd 100644
> --- a/qemu-options.hx
> +++ b/qemu-options.hx
> @@ -779,6 +779,12 @@ DEF("audiodev", HAS_ARG, QEMU_OPTION_audiodev,
>      "                in|out.name= source/sink device name\n"
>      "                in|out.latency= desired latency in microseconds\n"
>  #endif
> +#ifdef CONFIG_AUDIO_PIPEWIRE
> +    "-audiodev pipewire,id=id[,prop[=value][,...]]\n"
> +    "                in|out.name= source/sink device name\n"
> +    "                in|out.stream-name= name of pipewire stream\n"
> +    "                in|out.latency= desired latency in microseconds\n"
> +#endif
>  #ifdef CONFIG_AUDIO_SDL
>      "-audiodev sdl,id=id[,prop[=value][,...]]\n"
>      "                in|out.buffer-count= number of buffers\n"
> @@ -942,6 +948,21 @@ SRST
>          Desired latency in microseconds. The PulseAudio server will try
>          to honor this value but actual latencies may be lower or higher.
>
> +``-audiodev pipewire,id=id[,prop[=value][,...]]``
> +    Creates a backend using Pipewire. This backend is available on
> +    most systems.
> +
> +    Pipewire specific options are:
> +
> +    ``in|out.latency=usecs``
> +        Desired latency in microseconds.
> +
> +    ``in|out.name=sink``
> +        Use the specified source/sink for recording/playback.
> +
> +    ``in|out.stream-name``
> +        Specify the name of pipewire stream.
> +
>  ``-audiodev sdl,id=id[,prop[=value][,...]]``
>      Creates a backend using SDL. This backend is available on most
>      systems, but you should use your platform's native backend if
> diff --git a/scripts/meson-buildoptions.sh b/scripts/meson-buildoptions.sh
> index 009fab1515..ba1057b62c 100644
> --- a/scripts/meson-buildoptions.sh
> +++ b/scripts/meson-buildoptions.sh
> @@ -1,7 +1,8 @@
>  # This file is generated by meson-buildoptions.py, do not edit!
>  meson_options_help() {
> -  printf "%s\n" '  --audio-drv-list=CHOICES Set audio driver list [default] (choices: alsa/co'
> -  printf "%s\n" '                           reaudio/default/dsound/jack/oss/pa/sdl/sndio)'
> +  printf "%s\n" '  --audio-drv-list=CHOICES Set audio driver list [default] (choices: al'
> +  printf "%s\n" '                           sa/coreaudio/default/dsound/jack/oss/pa/'
> +  printf "%s\n" '                           pipewire/sdl/sndio)'
>    printf "%s\n" '  --block-drv-ro-whitelist=VALUE'
>    printf "%s\n" '                           set block driver read-only whitelist (by default'
>    printf "%s\n" '                           affects only QEMU, not tools like qemu-img)'
> @@ -136,6 +137,7 @@ meson_options_help() {
>    printf "%s\n" '  oss             OSS sound support'
>    printf "%s\n" '  pa              PulseAudio sound support'
>    printf "%s\n" '  parallels       parallels image format support'
> +  printf "%s\n" '  pipewire        Pipewire sound support'
>    printf "%s\n" '  png             PNG support with libpng'
>    printf "%s\n" '  pvrdma          Enable PVRDMA support'
>    printf "%s\n" '  qcow1           qcow1 image format support'
> @@ -370,6 +372,8 @@ _meson_option_parse() {
>      --disable-pa) printf "%s" -Dpa=disabled ;;
>      --enable-parallels) printf "%s" -Dparallels=enabled ;;
>      --disable-parallels) printf "%s" -Dparallels=disabled ;;
> +    --enable-pipewire) printf "%s" -Dpipewire=enabled ;;
> +    --disable-pipewire) printf "%s" -Dpipewire=disabled ;;
>      --with-pkgversion=*) quote_sh "-Dpkgversion=$2" ;;
>      --enable-png) printf "%s" -Dpng=enabled ;;
>      --disable-png) printf "%s" -Dpng=disabled ;;
> --
> 2.39.1
>


--
Marc-André Lureau
Re: [PATCH v9] audio/pwaudio.c: Add Pipewire audio backend for QEMU
Posted by Dorinda Bassey 1 year ago
Hi Marc-André,

...but queue 0. Look like you don't need the memset() after all.

I thought so too, however Volker wanted it there.

I understand it may be desirable to have a trace for stream state
> change. But the implementation could be simpler, no switch involved,
> and easier to read, simply change the code to:
>
>  trace_pw_state_changed(pw_stream_get_node_id(v->stream),
> pw_stream_state_as_string(state));
>
Ack

What is 3/4 for? I might have missed previous discussions, it would be
> worth explaining and adding a trace for the value.
>
Volker said that "The PW_KEY_NODE_LATENCY property is a hint for Pipewire
that we need
updates faster than timer_period. I selected 75% of timer-period. Then
there's a good chance the audio frontends can write or read new audio
packets every timer-period. It doesn't matter that Pipewire calls the
callbacks faster in most cases."
I would add a trace for the value.

This field and enum is not necessary if you simply pass a PW_DIRECTION
> down to create_stream().
>
Ack

It looks like you could easily factorize the 2 functions (an extra
> function with PWVoice argument).
>
I think it's better to keep it simple, as this can increase the overall
complexity of the code.

I don't understand how this works. The API doc says:
> "Signal the thread of loop. If wait_for_accept is true, this function
> waits until pw_thread_loop_accept() is called."
>
> And, the associated waiting function is pw_thread_loop_wait(). Can you
> explain where it is called from? (since it's not in this file)
>
The second parameter passed to the pw_thread_loop_signal function is a bool
value that specifies whether the function should wait for the signal to be
accepted or return immediately. If the value is true, the function will
wait until the signal is accepted by a call to pw_thread_loop_accept(). If
the value is false, the function will return immediately after sending the
signal. I alway thought that In this case it is false so it is not waiting
for any call to pw_thread_loop_accept(), but I'm wrong It actually needs
the associated waiting function pw_thread_loop_wait(). I would fix that
along with the use of pw->seq thanks.

You should clean up in reverse order of initialization, no?
>
Yes, context_destroy before loop_destroy actually.

No lock needed?
>
yes, no lock needed.

Are you sure stopping the loop before ending the core and the context
> associated with it here is fine?
>
yes, It's fine, however I would improve it.

Thanks,
Dorinda.


On Wed, Mar 29, 2023 at 10:19 AM Marc-André Lureau <
marcandre.lureau@gmail.com> wrote:

> Hi Dorinda,
>
> On Tue, Mar 28, 2023 at 5:08 PM Dorinda Bassey <dbassey@redhat.com> wrote:
> >
> > This commit adds a new audiodev backend to allow QEMU to use Pipewire as
> > both an audio sink and source. This backend is available on most systems
> >
> > Add Pipewire entry points for QEMU Pipewire audio backend
> > Add wrappers for QEMU Pipewire audio backend in qpw_pcm_ops()
> > qpw_write function returns the current state of the stream to pwaudio
> > and Writes some data to the server for playback streams using pipewire
> > spa_ringbuffer implementation.
> > qpw_read function returns the current state of the stream to pwaudio and
> > reads some data from the server for capture streams using pipewire
> > spa_ringbuffer implementation. These functions qpw_write and qpw_read
> > are called during playback and capture.
> > Added some functions that convert pw audio formats to QEMU audio format
> > and vice versa which would be needed in the pipewire audio sink and
> > source functions qpw_init_in() & qpw_init_out().
> > These methods that implement playback and recording will create streams
> > for playback and capture that will start processing and will result in
> > the on_process callbacks to be called.
> > Built a connection to the Pipewire sound system server in the
> > qpw_audio_init() method.
> >
> > Signed-off-by: Dorinda Bassey <dbassey@redhat.com>
> > ---
> > v9:
> > add code to play silence on a buffer underrun
> > remove redundant block in playback and capture process functions
> > refactor code for enabling/disabling audio stream
> > add volume_out and volume_in pcm_ops function
> > add code for in|out.name options
> > add in|out.stream-name options
> > fix format specifiers
> > change release version
> > add missing latency option
> >
> >  audio/audio.c                 |   3 +
> >  audio/audio_template.h        |   4 +
> >  audio/meson.build             |   1 +
> >  audio/pwaudio.c               | 879 ++++++++++++++++++++++++++++++++++
> >  audio/trace-events            |   8 +
> >  meson.build                   |   8 +
> >  meson_options.txt             |   4 +-
> >  qapi/audio.json               |  44 ++
> >  qemu-options.hx               |  21 +
> >  scripts/meson-buildoptions.sh |   8 +-
> >  10 files changed, 977 insertions(+), 3 deletions(-)
> >  create mode 100644 audio/pwaudio.c
> >
> > diff --git a/audio/audio.c b/audio/audio.c
> > index 70b096713c..90c7c49d11 100644
> > --- a/audio/audio.c
> > +++ b/audio/audio.c
> > @@ -2061,6 +2061,9 @@ void audio_create_pdos(Audiodev *dev)
> >  #ifdef CONFIG_AUDIO_PA
> >          CASE(PA, pa, Pa);
> >  #endif
> > +#ifdef CONFIG_AUDIO_PIPEWIRE
> > +        CASE(PIPEWIRE, pipewire, Pipewire);
> > +#endif
> >  #ifdef CONFIG_AUDIO_SDL
> >          CASE(SDL, sdl, Sdl);
> >  #endif
> > diff --git a/audio/audio_template.h b/audio/audio_template.h
> > index e42326c20d..dc0c74aa74 100644
> > --- a/audio/audio_template.h
> > +++ b/audio/audio_template.h
> > @@ -362,6 +362,10 @@ AudiodevPerDirectionOptions *glue(audio_get_pdo_,
> TYPE)(Audiodev *dev)
> >      case AUDIODEV_DRIVER_PA:
> >          return qapi_AudiodevPaPerDirectionOptions_base(dev->u.pa.TYPE);
> >  #endif
> > +#ifdef CONFIG_AUDIO_PIPEWIRE
> > +    case AUDIODEV_DRIVER_PIPEWIRE:
> > +        return
> qapi_AudiodevPipewirePerDirectionOptions_base(dev->u.pipewire.TYPE);
> > +#endif
> >  #ifdef CONFIG_AUDIO_SDL
> >      case AUDIODEV_DRIVER_SDL:
> >          return
> qapi_AudiodevSdlPerDirectionOptions_base(dev->u.sdl.TYPE);
> > diff --git a/audio/meson.build b/audio/meson.build
> > index 0722224ba9..65a49c1a10 100644
> > --- a/audio/meson.build
> > +++ b/audio/meson.build
> > @@ -19,6 +19,7 @@ foreach m : [
> >    ['sdl', sdl, files('sdlaudio.c')],
> >    ['jack', jack, files('jackaudio.c')],
> >    ['sndio', sndio, files('sndioaudio.c')],
> > +  ['pipewire', pipewire, files('pwaudio.c')],
> >    ['spice', spice, files('spiceaudio.c')]
> >  ]
> >    if m[1].found()
> > diff --git a/audio/pwaudio.c b/audio/pwaudio.c
> > new file mode 100644
> > index 0000000000..ca83bc55f9
> > --- /dev/null
> > +++ b/audio/pwaudio.c
> > @@ -0,0 +1,879 @@
> > +/*
> > + * QEMU Pipewire audio driver
> > + *
> > + * Copyright (c) 2023 Red Hat Inc.
> > + *
> > + * Author: Dorinda Bassey       <dbassey@redhat.com>
> > + *
> > + * SPDX-License-Identifier: GPL-2.0-or-later
> > + */
> > +
> > +#include "qemu/osdep.h"
> > +#include "qemu/module.h"
> > +#include "audio.h"
> > +#include <errno.h>
> > +#include "qemu/error-report.h"
> > +#include <spa/param/audio/format-utils.h>
> > +#include <spa/utils/ringbuffer.h>
> > +#include <spa/utils/result.h>
> > +#include <spa/param/props.h>
> > +
> > +#include <pipewire/pipewire.h>
> > +#include "trace.h"
> > +
> > +#define AUDIO_CAP "pipewire"
> > +#define RINGBUFFER_SIZE    (1u << 22)
> > +#define RINGBUFFER_MASK    (RINGBUFFER_SIZE - 1)
> > +
> > +#include "audio_int.h"
> > +
> > +enum {
> > +    MODE_SINK,
> > +    MODE_SOURCE
> > +};
> > +
> > +typedef struct pwvolume {
> > +    uint32_t channels;
> > +    float values[SPA_AUDIO_MAX_CHANNELS];
> > +} pwvolume;
> > +
> > +typedef struct pwaudio {
> > +    Audiodev *dev;
> > +    struct pw_thread_loop *thread_loop;
> > +    struct pw_context *context;
> > +
> > +    struct pw_core *core;
> > +    struct spa_hook core_listener;
> > +    int seq;
> > +} pwaudio;
> > +
> > +typedef struct PWVoice {
> > +    pwaudio *g;
> > +    struct pw_stream *stream;
> > +    struct spa_hook stream_listener;
> > +    struct spa_audio_info_raw info;
> > +    uint32_t highwater_mark;
> > +    uint32_t frame_size;
> > +    struct spa_ringbuffer ring;
> > +    uint8_t buffer[RINGBUFFER_SIZE];
> > +
> > +    uint32_t mode;
> > +    struct pw_properties *props;
> > +    pwvolume volume;
> > +    bool muted;
> > +} PWVoice;
> > +
> > +typedef struct PWVoiceOut {
> > +    HWVoiceOut hw;
> > +    PWVoice v;
> > +} PWVoiceOut;
> > +
> > +typedef struct PWVoiceIn {
> > +    HWVoiceIn hw;
> > +    PWVoice v;
> > +} PWVoiceIn;
> > +
> > +static void
> > +stream_destroy(void *data)
> > +{
> > +    PWVoice *v = (PWVoice *) data;
> > +    spa_hook_remove(&v->stream_listener);
> > +    v->stream = NULL;
> > +}
> > +
> > +/* output data processing function to read stuffs from the buffer */
> > +static void
> > +playback_on_process(void *data)
> > +{
> > +    PWVoice *v = (PWVoice *) data;
> > +    void *p;
> > +    struct pw_buffer *b;
> > +    struct spa_buffer *buf;
> > +    uint32_t req, index, n_bytes;
> > +    int32_t avail;
> > +
> > +    if (!v->stream) {
> > +        return;
> > +    }
>
> Could you replace with an assert(v->stream) instead?
>
>
> > +
> > +    /* obtain a buffer to read from */
> > +    b = pw_stream_dequeue_buffer(v->stream);
> > +    if (b == NULL) {
> > +        error_report("out of buffers: %s", strerror(errno));
> > +        return;
> > +    }
> > +
> > +    buf = b->buffer;
> > +    p = buf->datas[0].data;
> > +    if (p == NULL) {
> > +        return;
> > +    }
> > +    /* calculate the total no of bytes to read data from buffer */
> > +    req = b->requested * v->frame_size;
> > +    if (req == 0) {
> > +        req = (uint64_t)v->g->dev->timer_period * v->info.rate
> > +                * 1 / 2 / 1000000 * v->frame_size;
> > +    }
> > +    n_bytes = SPA_MIN(req, buf->datas[0].maxsize);
> > +
> > +    /* get no of available bytes to read data from buffer */
> > +
> > +    avail = spa_ringbuffer_get_read_index(&v->ring, &index);
> > +
> > +
> > +    if (avail == 0) {
> > +        memset(p, 0, n_bytes);
>
> Clear the buffer...
>
> > +    }
> > +
> > +    if (avail < (int32_t) n_bytes) {
> > +        n_bytes = avail;
>
> ...but queue 0. Look like you don't need the memset() after all.
>
> > +    }
> > +
> > +    spa_ringbuffer_read_data(&v->ring,
> > +                                v->buffer, RINGBUFFER_SIZE,
> > +                                index & RINGBUFFER_MASK, p, n_bytes);
> > +
> > +    index += n_bytes;
> > +    spa_ringbuffer_read_update(&v->ring, index);
> > +
> > +    buf->datas[0].chunk->offset = 0;
> > +    buf->datas[0].chunk->stride = v->frame_size;
> > +    buf->datas[0].chunk->size = n_bytes;
> > +
> > +    /* queue the buffer for playback */
> > +    pw_stream_queue_buffer(v->stream, b);
> > +}
> > +
> > +/* output data processing function to generate stuffs in the buffer */
> > +static void
> > +capture_on_process(void *data)
> > +{
> > +    PWVoice *v = (PWVoice *) data;
> > +    void *p;
> > +    struct pw_buffer *b;
> > +    struct spa_buffer *buf;
> > +    int32_t filled;
> > +    uint32_t index, offs, n_bytes;
> > +
> > +    if (!v->stream) {
> > +        return;
> > +    }
>
> Could you replace with an assert(v->stream) instead?
>
> > +
> > +    /* obtain a buffer */
> > +    b = pw_stream_dequeue_buffer(v->stream);
> > +    if (b == NULL) {
> > +        error_report("out of buffers: %s", strerror(errno));
> > +        return;
> > +    }
> > +
> > +    /* Write data into buffer */
> > +    buf = b->buffer;
> > +    p = buf->datas[0].data;
> > +    if (p == NULL) {
> > +        return;
> > +    }
> > +    offs = SPA_MIN(buf->datas[0].chunk->offset, buf->datas[0].maxsize);
> > +    n_bytes = SPA_MIN(buf->datas[0].chunk->size, buf->datas[0].maxsize
> - offs);
> > +
> > +    filled = spa_ringbuffer_get_write_index(&v->ring, &index);
> > +
> > +
> > +    if (filled < 0) {
> > +        error_report("%p: underrun write:%u filled:%d", p, index,
> filled);
> > +    } else {
> > +        if ((uint32_t) filled + n_bytes > RINGBUFFER_SIZE) {
> > +            error_report("%p: overrun write:%u filled:%d + size:%u >
> max:%u",
> > +            p, index, filled, n_bytes, RINGBUFFER_SIZE);
> > +        }
> > +    }
> > +    spa_ringbuffer_write_data(&v->ring,
> > +                                v->buffer, RINGBUFFER_SIZE,
> > +                                index & RINGBUFFER_MASK,
> > +                                SPA_PTROFF(p, offs, void), n_bytes);
> > +    index += n_bytes;
> > +    spa_ringbuffer_write_update(&v->ring, index);
> > +
> > +    /* queue the buffer for playback */
> > +    pw_stream_queue_buffer(v->stream, b);
> > +}
> > +
> > +static void
> > +on_stream_state_changed(void *_data, enum pw_stream_state old,
> > +                        enum pw_stream_state state, const char *error)
> > +{
> > +    PWVoice *v = (PWVoice *) _data;
>
> why not simply name it "data"?
>
> > +
> > +    trace_pw_state_changed(pw_stream_state_as_string(state));
> > +
> > +    switch (state) {
> > +    case PW_STREAM_STATE_ERROR:
> > +    case PW_STREAM_STATE_UNCONNECTED:
> > +        {
> > +            break;
> > +        }
>
> hmm..
>
> > +    case PW_STREAM_STATE_PAUSED:
> > +        trace_pw_node(pw_stream_get_node_id(v->stream));
> > +        break;
> > +    case PW_STREAM_STATE_CONNECTING:
> > +    case PW_STREAM_STATE_STREAMING:
> > +        break;
> > +    }
>
> I understand it may be desirable to have a trace for stream state
> change. But the implementation could be simpler, no switch involved,
> and easier to read, simply change the code to:
>
>  trace_pw_state_changed(pw_stream_get_node_id(v->stream),
> pw_stream_state_as_string(state));
>
>
> > +}
> > +
> > +static const struct pw_stream_events capture_stream_events = {
> > +    PW_VERSION_STREAM_EVENTS,
> > +    .destroy = stream_destroy,
> > +    .state_changed = on_stream_state_changed,
> > +    .process = capture_on_process
> > +};
> > +
> > +static const struct pw_stream_events playback_stream_events = {
> > +    PW_VERSION_STREAM_EVENTS,
> > +    .destroy = stream_destroy,
> > +    .state_changed = on_stream_state_changed,
> > +    .process = playback_on_process
> > +};
> > +
> > +static size_t
> > +qpw_read(HWVoiceIn *hw, void *data, size_t len)
> > +{
> > +    PWVoiceIn *pw = (PWVoiceIn *) hw;
> > +    PWVoice *v = &pw->v;
> > +    pwaudio *c = v->g;
> > +    const char *error = NULL;
> > +    size_t l;
> > +    int32_t avail;
> > +    uint32_t index;
> > +
> > +    pw_thread_loop_lock(c->thread_loop);
> > +    if (pw_stream_get_state(v->stream, &error) !=
> PW_STREAM_STATE_STREAMING) {
> > +        /* wait for stream to become ready */
> > +        l = 0;
> > +        goto done_unlock;
> > +    }
> > +    /* get no of available bytes to read data from buffer */
> > +    avail = spa_ringbuffer_get_read_index(&v->ring, &index);
> > +
> > +    trace_pw_read(avail, index, len);
> > +
> > +    if (avail < (int32_t) len) {
> > +        len = avail;
> > +    }
> > +
> > +    spa_ringbuffer_read_data(&v->ring,
> > +                             v->buffer, RINGBUFFER_SIZE,
> > +                             index & RINGBUFFER_MASK, data, len);
> > +    index += len;
> > +    spa_ringbuffer_read_update(&v->ring, index);
> > +    l = len;
> > +
> > +done_unlock:
> > +    pw_thread_loop_unlock(c->thread_loop);
> > +    return l;
> > +}
> > +
> > +static size_t qpw_buffer_get_free(HWVoiceOut *hw)
> > +{
> > +    PWVoiceOut *pw = (PWVoiceOut *)hw;
> > +    PWVoice *v = &pw->v;
> > +    pwaudio *c = v->g;
> > +    const char *error = NULL;
> > +    int32_t filled, avail;
> > +    uint32_t index;
> > +
> > +    pw_thread_loop_lock(c->thread_loop);
> > +    if (pw_stream_get_state(v->stream, &error) !=
> PW_STREAM_STATE_STREAMING) {
> > +        /* wait for stream to become ready */
> > +        avail = 0;
> > +        goto done_unlock;
> > +    }
> > +
> > +    filled = spa_ringbuffer_get_write_index(&v->ring, &index);
> > +    avail = v->highwater_mark - filled;
> > +
> > +done_unlock:
> > +    pw_thread_loop_unlock(c->thread_loop);
> > +    return avail;
> > +}
> > +
> > +static size_t
> > +qpw_write(HWVoiceOut *hw, void *data, size_t len)
> > +{
> > +    PWVoiceOut *pw = (PWVoiceOut *) hw;
> > +    PWVoice *v = &pw->v;
> > +    pwaudio *c = v->g;
> > +    const char *error = NULL;
> > +    int32_t filled, avail;
> > +    uint32_t index;
> > +
> > +    pw_thread_loop_lock(c->thread_loop);
> > +    if (pw_stream_get_state(v->stream, &error) !=
> PW_STREAM_STATE_STREAMING) {
> > +        /* wait for stream to become ready */
> > +        len = 0;
> > +        goto done_unlock;
> > +    }
> > +    filled = spa_ringbuffer_get_write_index(&v->ring, &index);
> > +    avail = v->highwater_mark - filled;
> > +
> > +    trace_pw_write(filled, avail, index, len);
> > +
> > +    if (len > avail) {
> > +        len = avail;
> > +    }
> > +
> > +    if (filled < 0) {
> > +        error_report("%p: underrun write:%u filled:%d", pw, index,
> filled);
> > +    } else {
> > +        if ((uint32_t) filled + len > RINGBUFFER_SIZE) {
> > +            error_report("%p: overrun write:%u filled:%d + size:%zu >
> max:%u",
> > +            pw, index, filled, len, RINGBUFFER_SIZE);
> > +        }
> > +    }
> > +
> > +    spa_ringbuffer_write_data(&v->ring,
> > +                                v->buffer, RINGBUFFER_SIZE,
> > +                                index & RINGBUFFER_MASK, data, len);
> > +    index += len;
> > +    spa_ringbuffer_write_update(&v->ring, index);
> > +
> > +done_unlock:
> > +    pw_thread_loop_unlock(c->thread_loop);
> > +    return len;
> > +}
> > +
> > +static int
> > +audfmt_to_pw(AudioFormat fmt, int endianness)
> > +{
> > +    int format;
> > +
> > +    switch (fmt) {
> > +    case AUDIO_FORMAT_S8:
> > +        format = SPA_AUDIO_FORMAT_S8;
> > +        break;
> > +    case AUDIO_FORMAT_U8:
> > +        format = SPA_AUDIO_FORMAT_U8;
> > +        break;
> > +    case AUDIO_FORMAT_S16:
> > +        format = endianness ? SPA_AUDIO_FORMAT_S16_BE :
> SPA_AUDIO_FORMAT_S16_LE;
> > +        break;
> > +    case AUDIO_FORMAT_U16:
> > +        format = endianness ? SPA_AUDIO_FORMAT_U16_BE :
> SPA_AUDIO_FORMAT_U16_LE;
> > +        break;
> > +    case AUDIO_FORMAT_S32:
> > +        format = endianness ? SPA_AUDIO_FORMAT_S32_BE :
> SPA_AUDIO_FORMAT_S32_LE;
> > +        break;
> > +    case AUDIO_FORMAT_U32:
> > +        format = endianness ? SPA_AUDIO_FORMAT_U32_BE :
> SPA_AUDIO_FORMAT_U32_LE;
> > +        break;
> > +    case AUDIO_FORMAT_F32:
> > +        format = endianness ? SPA_AUDIO_FORMAT_F32_BE :
> SPA_AUDIO_FORMAT_F32_LE;
> > +        break;
> > +    default:
> > +        dolog("Internal logic error: Bad audio format %d\n", fmt);
> > +        format = SPA_AUDIO_FORMAT_U8;
> > +        break;
> > +    }
> > +    return format;
> > +}
> > +
> > +static AudioFormat
> > +pw_to_audfmt(enum spa_audio_format fmt, int *endianness,
> > +             uint32_t *frame_size)
> > +{
> > +    switch (fmt) {
> > +    case SPA_AUDIO_FORMAT_S8:
> > +        *frame_size = 1;
> > +        return AUDIO_FORMAT_S8;
> > +    case SPA_AUDIO_FORMAT_U8:
> > +        *frame_size = 1;
> > +        return AUDIO_FORMAT_U8;
> > +    case SPA_AUDIO_FORMAT_S16_BE:
> > +        *frame_size = 2;
> > +        *endianness = 1;
> > +        return AUDIO_FORMAT_S16;
> > +    case SPA_AUDIO_FORMAT_S16_LE:
> > +        *frame_size = 2;
> > +        *endianness = 0;
> > +        return AUDIO_FORMAT_S16;
> > +    case SPA_AUDIO_FORMAT_U16_BE:
> > +        *frame_size = 2;
> > +        *endianness = 1;
> > +        return AUDIO_FORMAT_U16;
> > +    case SPA_AUDIO_FORMAT_U16_LE:
> > +        *frame_size = 2;
> > +        *endianness = 0;
> > +        return AUDIO_FORMAT_U16;
> > +    case SPA_AUDIO_FORMAT_S32_BE:
> > +        *frame_size = 4;
> > +        *endianness = 1;
> > +        return AUDIO_FORMAT_S32;
> > +    case SPA_AUDIO_FORMAT_S32_LE:
> > +        *frame_size = 4;
> > +        *endianness = 0;
> > +        return AUDIO_FORMAT_S32;
> > +    case SPA_AUDIO_FORMAT_U32_BE:
> > +        *frame_size = 4;
> > +        *endianness = 1;
> > +        return AUDIO_FORMAT_U32;
> > +    case SPA_AUDIO_FORMAT_U32_LE:
> > +        *frame_size = 4;
> > +        *endianness = 0;
> > +        return AUDIO_FORMAT_U32;
> > +    case SPA_AUDIO_FORMAT_F32_BE:
> > +        *frame_size = 4;
> > +        *endianness = 1;
> > +        return AUDIO_FORMAT_F32;
> > +    case SPA_AUDIO_FORMAT_F32_LE:
> > +        *frame_size = 4;
> > +        *endianness = 0;
> > +        return AUDIO_FORMAT_F32;
> > +    default:
> > +        *frame_size = 1;
> > +        dolog("Internal logic error: Bad spa_audio_format %d\n", fmt);
> > +        return AUDIO_FORMAT_U8;
> > +    }
> > +}
> > +
> > +static int
> > +create_stream(pwaudio *c, PWVoice *v, const char *stream_name, const
> char *name)
> > +{
> > +    int res;
> > +    uint32_t n_params;
> > +    const struct spa_pod *params[2];
> > +    uint8_t buffer[1024];
> > +    struct spa_pod_builder b;
> > +
> > +    v->props = pw_properties_new(NULL, NULL);
> > +    pw_properties_setf(v->props, PW_KEY_NODE_LATENCY, "%" PRIu64 "/%u",
> > +                       (uint64_t)v->g->dev->timer_period * v->info.rate
> > +                       * 3 / 4 / 1000000, v->info.rate);
>
> What is 3/4 for? I might have missed previous discussions, it would be
> worth explaining and adding a trace for the value.
>
> > +    if (name) {
> > +        pw_properties_set(v->props, PW_KEY_TARGET_OBJECT, name);
> > +    }
> > +    v->stream = pw_stream_new(c->core, stream_name, v->props);
> > +
> > +    if (v->stream == NULL) {
> > +        return -1;
> > +    }
> > +
> > +    if (v->mode == MODE_SOURCE) {
> > +        pw_stream_add_listener(v->stream,
> > +                            &v->stream_listener,
> &capture_stream_events, v);
> > +    } else {
> > +        pw_stream_add_listener(v->stream,
> > +                            &v->stream_listener,
> &playback_stream_events, v);
> > +    }
> > +
> > +    n_params = 0;
> > +    spa_pod_builder_init(&b, buffer, sizeof(buffer));
> > +    params[n_params++] = spa_format_audio_raw_build(&b,
> > +                            SPA_PARAM_EnumFormat,
> > +                            &v->info);
> > +
> > +    /* connect the stream to a sink or source */
> > +    res = pw_stream_connect(v->stream,
> > +                            v->mode ==
> > +                            MODE_SOURCE ? PW_DIRECTION_INPUT :
> > +                            PW_DIRECTION_OUTPUT, PW_ID_ANY,
> > +                            PW_STREAM_FLAG_AUTOCONNECT |
> > +                            PW_STREAM_FLAG_INACTIVE |
> > +                            PW_STREAM_FLAG_MAP_BUFFERS |
> > +                            PW_STREAM_FLAG_RT_PROCESS, params,
> n_params);
> > +    if (res < 0) {
> > +        pw_stream_destroy(v->stream);
> > +        return -1;
> > +    }
> > +
> > +    return 0;
> > +}
> > +
> > +static int
> > +qpw_stream_new(pwaudio *c, PWVoice *v,
> > +               const char *stream_name, const char *name)
> > +{
> > +    int r;
> > +
> > +    switch (v->info.channels) {
> > +    case 8:
> > +        v->info.position[0] = SPA_AUDIO_CHANNEL_FL;
> > +        v->info.position[1] = SPA_AUDIO_CHANNEL_FR;
> > +        v->info.position[2] = SPA_AUDIO_CHANNEL_FC;
> > +        v->info.position[3] = SPA_AUDIO_CHANNEL_LFE;
> > +        v->info.position[4] = SPA_AUDIO_CHANNEL_RL;
> > +        v->info.position[5] = SPA_AUDIO_CHANNEL_RR;
> > +        v->info.position[6] = SPA_AUDIO_CHANNEL_SL;
> > +        v->info.position[7] = SPA_AUDIO_CHANNEL_SR;
> > +        break;
> > +    case 6:
> > +        v->info.position[0] = SPA_AUDIO_CHANNEL_FL;
> > +        v->info.position[1] = SPA_AUDIO_CHANNEL_FR;
> > +        v->info.position[2] = SPA_AUDIO_CHANNEL_FC;
> > +        v->info.position[3] = SPA_AUDIO_CHANNEL_LFE;
> > +        v->info.position[4] = SPA_AUDIO_CHANNEL_RL;
> > +        v->info.position[5] = SPA_AUDIO_CHANNEL_RR;
> > +        break;
> > +    case 5:
> > +        v->info.position[0] = SPA_AUDIO_CHANNEL_FL;
> > +        v->info.position[1] = SPA_AUDIO_CHANNEL_FR;
> > +        v->info.position[2] = SPA_AUDIO_CHANNEL_FC;
> > +        v->info.position[3] = SPA_AUDIO_CHANNEL_LFE;
> > +        v->info.position[4] = SPA_AUDIO_CHANNEL_RC;
> > +        break;
> > +    case 4:
> > +        v->info.position[0] = SPA_AUDIO_CHANNEL_FL;
> > +        v->info.position[1] = SPA_AUDIO_CHANNEL_FR;
> > +        v->info.position[2] = SPA_AUDIO_CHANNEL_FC;
> > +        v->info.position[3] = SPA_AUDIO_CHANNEL_RC;
> > +        break;
> > +    case 3:
> > +        v->info.position[0] = SPA_AUDIO_CHANNEL_FL;
> > +        v->info.position[1] = SPA_AUDIO_CHANNEL_FR;
> > +        v->info.position[2] = SPA_AUDIO_CHANNEL_LFE;
> > +        break;
> > +    case 2:
> > +        v->info.position[0] = SPA_AUDIO_CHANNEL_FL;
> > +        v->info.position[1] = SPA_AUDIO_CHANNEL_FR;
> > +        break;
> > +    case 1:
> > +        v->info.position[0] = SPA_AUDIO_CHANNEL_MONO;
> > +        break;
> > +    default:
> > +        for (size_t i = 0; i < v->info.channels; i++) {
> > +            v->info.position[i] = SPA_AUDIO_CHANNEL_UNKNOWN;
> > +        }
> > +        break;
> > +    }
> > +
> > +    /* create a new unconnected pwstream */
> > +    r = create_stream(c, v, stream_name, name);
> > +    if (r < 0) {
> > +        AUD_log(AUDIO_CAP, "Failed to create stream.");
> > +        return -1;
> > +    }
> > +
> > +    return r;
> > +}
> > +
> > +static int
> > +qpw_init_out(HWVoiceOut *hw, struct audsettings *as, void *drv_opaque)
> > +{
> > +    PWVoiceOut *pw = (PWVoiceOut *) hw;
> > +    PWVoice *v = &pw->v;
> > +    struct audsettings obt_as = *as;
> > +    pwaudio *c = v->g = drv_opaque;
> > +    AudiodevPipewireOptions *popts = &c->dev->u.pipewire;
> > +    AudiodevPipewirePerDirectionOptions *ppdo = popts->out;
> > +    int r;
> > +
> > +    v->mode = MODE_SINK;
>
> This field and enum is not necessary if you simply pass a PW_DIRECTION
> down to create_stream().
>
> > +
> > +    pw_thread_loop_lock(c->thread_loop);
> > +
> > +    v->info.format = audfmt_to_pw(as->fmt, as->endianness);
> > +    v->info.channels = as->nchannels;
> > +    v->info.rate = as->freq;
> > +
> > +    obt_as.fmt =
> > +        pw_to_audfmt(v->info.format, &obt_as.endianness,
> &v->frame_size);
> > +    v->frame_size *= as->nchannels;
> > +
> > +    /* call the function that creates a new stream for playback */
> > +    r = qpw_stream_new(c, v, ppdo->stream_name ? : c->dev->id,
> ppdo->name);
> > +    if (r < 0) {
> > +        error_report("qpw_stream_new for playback failed");
> > +        pw_thread_loop_unlock(c->thread_loop);
> > +        return -1;
> > +    }
> > +
> > +    /* report the audio format we support */
> > +    audio_pcm_init_info(&hw->info, &obt_as);
> > +
> > +    /* report the buffer size to qemu */
> > +    hw->samples = audio_buffer_frames(
> > +        qapi_AudiodevPipewirePerDirectionOptions_base(ppdo), &obt_as,
> 46440);
> > +    v->highwater_mark = MIN(RINGBUFFER_SIZE,
> > +                            (ppdo->has_latency ? ppdo->latency : 46440)
> > +                            * (uint64_t)v->info.rate / 1000000 *
> v->frame_size);
> > +
> > +    pw_thread_loop_unlock(c->thread_loop);
> > +    return 0;
> > +}
> > +
> > +static int
> > +qpw_init_in(HWVoiceIn *hw, struct audsettings *as, void *drv_opaque)
> > +{
> > +    PWVoiceIn *pw = (PWVoiceIn *) hw;
> > +    PWVoice *v = &pw->v;
> > +    struct audsettings obt_as = *as;
> > +    pwaudio *c = v->g = drv_opaque;
> > +    AudiodevPipewireOptions *popts = &c->dev->u.pipewire;
> > +    AudiodevPipewirePerDirectionOptions *ppdo = popts->in;
> > +    int r;
> > +
> > +    v->mode = MODE_SOURCE;
> > +    pw_thread_loop_lock(c->thread_loop);
> > +
> > +    v->info.format = audfmt_to_pw(as->fmt, as->endianness);
> > +    v->info.channels = as->nchannels;
> > +    v->info.rate = as->freq;
> > +
> > +    obt_as.fmt =
> > +        pw_to_audfmt(v->info.format, &obt_as.endianness,
> &v->frame_size);
> > +    v->frame_size *= as->nchannels;
> > +
> > +    /* call the function that creates a new stream for recording */
> > +    r = qpw_stream_new(c, v, ppdo->stream_name ? : c->dev->id,
> ppdo->name);
> > +    if (r < 0) {
> > +        error_report("qpw_stream_new for recording failed");
> > +        pw_thread_loop_unlock(c->thread_loop);
> > +        return -1;
> > +    }
> > +
> > +    /* report the audio format we support */
> > +    audio_pcm_init_info(&hw->info, &obt_as);
> > +
> > +    /* report the buffer size to qemu */
> > +    hw->samples = audio_buffer_frames(
> > +        qapi_AudiodevPipewirePerDirectionOptions_base(ppdo), &obt_as,
> 46440);
> > +
> > +    pw_thread_loop_unlock(c->thread_loop);
> > +    return 0;
> > +}
> > +
> > +static void
> > +qpw_fini_out(HWVoiceOut *hw)
> > +{
> > +    PWVoiceOut *pw = (PWVoiceOut *) hw;
> > +    PWVoice *v = &pw->v;
> > +
> > +    if (v->stream) {
> > +        pwaudio *c = v->g;
> > +        pw_thread_loop_lock(c->thread_loop);
> > +        pw_stream_destroy(v->stream);
> > +        v->stream = NULL;
> > +        pw_thread_loop_unlock(c->thread_loop);
> > +    }
> > +}
> > +
> > +static void
> > +qpw_fini_in(HWVoiceIn *hw)
> > +{
> > +    PWVoiceIn *pw = (PWVoiceIn *) hw;
> > +    PWVoice *v = &pw->v;
> > +
> > +    if (v->stream) {
> > +        pwaudio *c = v->g;
> > +        pw_thread_loop_lock(c->thread_loop);
> > +        pw_stream_destroy(v->stream);
> > +        v->stream = NULL;
> > +        pw_thread_loop_unlock(c->thread_loop);
> > +    }
> > +}
>
> It looks like you could easily factorize the 2 functions (an extra
> function with PWVoice argument).
>
> > +
> > +static void
> > +qpw_enable_out(HWVoiceOut *hw, bool enable)
> > +{
> > +    PWVoiceOut *po = (PWVoiceOut *) hw;
> > +    PWVoice *v = &po->v;
> > +    pw_stream_set_active(v->stream, enable);
> > +}
> > +
> > +static void
> > +qpw_enable_in(HWVoiceIn *hw, bool enable)
> > +{
> > +    PWVoiceIn *pi = (PWVoiceIn *) hw;
> > +    PWVoice *v = &pi->v;
> > +    pw_stream_set_active(v->stream, enable);
> > +}
> > +
> > +static void
> > +qpw_volume_out(HWVoiceOut *hw, Volume *vol)
> > +{
> > +    PWVoiceOut *pw = (PWVoiceOut *) hw;
> > +    PWVoice *v = &pw->v;
> > +    pwaudio *c = v->g;
> > +    int i, ret;
> > +
> > +    pw_thread_loop_lock(c->thread_loop);
> > +    v->volume.channels = vol->channels;
> > +
> > +    for (i = 0; i < vol->channels; ++i) {
> > +        v->volume.values[i] = vol->vol[i] / 100;
> > +    }
> > +
> > +    ret = pw_stream_set_control(v->stream,
> > +        SPA_PROP_channelVolumes, v->volume.channels, v->volume.values,
> 0);
> > +    trace_pw_vol(ret == 0 ? "success" : "failed");
> > +
> > +    v->muted = vol->mute;
> > +    float val = v->muted ? 1.f : 0.f;
> > +    ret = pw_stream_set_control(v->stream, SPA_PROP_mute, 1, &val, 0);
> > +    pw_thread_loop_unlock(c->thread_loop);
> > +}
> > +
> > +static void
> > +qpw_volume_in(HWVoiceIn *hw, Volume *vol)
> > +{
> > +    PWVoiceIn *pw = (PWVoiceIn *) hw;
> > +    PWVoice *v = &pw->v;
> > +    pwaudio *c = v->g;
> > +    int i, ret;
> > +
> > +    pw_thread_loop_lock(c->thread_loop);
> > +    v->volume.channels = vol->channels;
> > +
> > +    for (i = 0; i < vol->channels; ++i) {
> > +        v->volume.values[i] = vol->vol[i] / 100;
> > +    }
> > +
> > +    ret = pw_stream_set_control(v->stream,
> > +        SPA_PROP_channelVolumes, v->volume.channels, v->volume.values,
> 0);
> > +    trace_pw_vol(ret == 0 ? "success" : "failed");
> > +
> > +    v->muted = vol->mute;
> > +    float val = v->muted ? 1.f : 0.f;
> > +    ret = pw_stream_set_control(v->stream, SPA_PROP_mute, 1, &val, 0);
> > +    pw_thread_loop_unlock(c->thread_loop);
> > +}
>
> It looks like you could easily factorize the 2 functions.
>
> > +
> > +static void
> > +on_core_error(void *data, uint32_t id, int seq, int res, const char
> *message)
> > +{
> > +    pwaudio *pw = data;
> > +
> > +    error_report("error id:%u seq:%d res:%d (%s): %s",
> > +                id, seq, res, spa_strerror(res), message);
> > +
> > +    /* stop and exit the thread loop */
> > +    pw_thread_loop_signal(pw->thread_loop, FALSE);
>
> I don't understand how this works. The API doc says:
> "Signal the thread of loop. If wait_for_accept is true, this function
> waits until pw_thread_loop_accept() is called."
>
> And, the associated waiting function is pw_thread_loop_wait(). Can you
> explain where it is called from? (since it's not in this file)
>
> > +}
> > +
> > +static void
> > +on_core_done(void *data, uint32_t id, int seq)
> > +{
> > +    pwaudio *pw = data;
> > +    if (id == PW_ID_CORE) {
> > +        pw->seq = seq;
> > +        /* stop and exit the thread loop */
> > +        pw_thread_loop_signal(pw->thread_loop, FALSE);
>
> (same remark about signal)
>
>
>
> What do you need pw->seq for?
>
> > +    }
> > +}
> > +
> > +static const struct pw_core_events core_events = {
> > +    PW_VERSION_CORE_EVENTS,
> > +    .done = on_core_done,
> > +    .error = on_core_error,
> > +};
> > +
> > +static void *
> > +qpw_audio_init(Audiodev *dev)
> > +{
> > +    g_autofree pwaudio *pw = g_new0(pwaudio, 1);
> > +    pw_init(NULL, NULL);
> > +
> > +    trace_pw_audio_init();
> > +    assert(dev->driver == AUDIODEV_DRIVER_PIPEWIRE);
> > +
> > +    pw->dev = dev;
> > +    pw->thread_loop = pw_thread_loop_new("Pipewire thread loop", NULL);
> > +    if (pw->thread_loop == NULL) {
> > +        error_report("Could not create Pipewire loop");
> > +        goto fail;
> > +    }
> > +
> > +    pw->context =
> > +        pw_context_new(pw_thread_loop_get_loop(pw->thread_loop), NULL,
> 0);
> > +    if (pw->context == NULL) {
> > +        error_report("Could not create Pipewire context");
> > +        goto fail;
> > +    }
> > +
> > +    if (pw_thread_loop_start(pw->thread_loop) < 0) {
> > +        error_report("Could not start Pipewire loop");
> > +        goto fail;
> > +    }
> > +
> > +    pw_thread_loop_lock(pw->thread_loop);
> > +
> > +    pw->core = pw_context_connect(pw->context, NULL, 0);
> > +    if (pw->core == NULL) {
> > +        pw_thread_loop_unlock(pw->thread_loop);
> > +        goto fail;
> > +    }
> > +
> > +    pw_core_add_listener(pw->core, &pw->core_listener, &core_events,
> pw);
> > +
> > +    pw_thread_loop_unlock(pw->thread_loop);
> > +
> > +    return g_steal_pointer(&pw);
> > +
> > +fail:
> > +    AUD_log(AUDIO_CAP, "Failed to initialize PW context");
> > +    if (pw->thread_loop) {
> > +        pw_thread_loop_stop(pw->thread_loop);
> > +        g_clear_pointer(&pw->thread_loop, pw_thread_loop_destroy);
> > +    }
> > +    if (pw->context) {
> > +        g_clear_pointer(&pw->context, pw_context_destroy);
> > +    }
>
> You should clean up in reverse order of initialization, no?
>
> > +    return NULL;
> > +}
> > +
> > +static void
> > +qpw_audio_fini(void *opaque)
> > +{
> > +    pwaudio *pw = opaque;
> > +
> > +    pw_thread_loop_stop(pw->thread_loop);
>
> No lock needed?
>
> Are you sure stopping the loop before ending the core and the context
> associated with it here is fine?
>
>
> > +
> > +    if (pw->core) {
> > +        spa_hook_remove(&pw->core_listener);
> > +        spa_zero(pw->core_listener);
> > +        pw_core_disconnect(pw->core);
> > +    }
> > +
> > +    if (pw->context) {
> > +        pw_context_destroy(pw->context);
> > +    }
> > +    pw_thread_loop_destroy(pw->thread_loop);
> > +
> > +    g_free(pw);
> > +}
> > +
> > +static struct audio_pcm_ops qpw_pcm_ops = {
> > +    .init_out = qpw_init_out,
> > +    .fini_out = qpw_fini_out,
> > +    .write = qpw_write,
> > +    .buffer_get_free = qpw_buffer_get_free,
> > +    .run_buffer_out = audio_generic_run_buffer_out,
> > +    .enable_out = qpw_enable_out,
> > +    .volume_out = qpw_volume_out,
> > +    .volume_in = qpw_volume_in,
> > +
> > +    .init_in = qpw_init_in,
> > +    .fini_in = qpw_fini_in,
> > +    .read = qpw_read,
> > +    .run_buffer_in = audio_generic_run_buffer_in,
> > +    .enable_in = qpw_enable_in
> > +};
> > +
> > +static struct audio_driver pw_audio_driver = {
> > +    .name = "pipewire",
> > +    .descr = "http://www.pipewire.org/",
> > +    .init = qpw_audio_init,
> > +    .fini = qpw_audio_fini,
> > +    .pcm_ops = &qpw_pcm_ops,
> > +    .can_be_default = 1,
> > +    .max_voices_out = INT_MAX,
> > +    .max_voices_in = INT_MAX,
> > +    .voice_size_out = sizeof(PWVoiceOut),
> > +    .voice_size_in = sizeof(PWVoiceIn),
> > +};
> > +
> > +static void
> > +register_audio_pw(void)
> > +{
> > +    audio_driver_register(&pw_audio_driver);
> > +}
> > +
> > +type_init(register_audio_pw);
> > diff --git a/audio/trace-events b/audio/trace-events
> > index e1ab643add..59ec817c9d 100644
> > --- a/audio/trace-events
> > +++ b/audio/trace-events
> > @@ -18,6 +18,14 @@ dbus_audio_register(const char *s, const char *dir)
> "sender = %s, dir = %s"
> >  dbus_audio_put_buffer_out(size_t len) "len = %zu"
> >  dbus_audio_read(size_t len) "len = %zu"
> >
> > +# pwaudio.c
> > +pw_state_changed(const char *s) "stream state: %s"
> > +pw_node(int nodeid) "node id: %d"
> > +pw_read(int32_t avail, uint32_t index, size_t len) "avail=%d index=%u
> len=%zu"
> > +pw_write(int32_t filled, int32_t avail, uint32_t index, size_t len)
> "filled=%d avail=%d index=%u len=%zu"
> > +pw_vol(const char *ret) "set volume: %s"
> > +pw_audio_init(void) "Initialize Pipewire context"
> > +
> >  # audio.c
> >  audio_timer_start(int interval) "interval %d ms"
> >  audio_timer_stop(void) ""
> > diff --git a/meson.build b/meson.build
> > index 29f8644d6d..31bf280c0d 100644
> > --- a/meson.build
> > +++ b/meson.build
> > @@ -730,6 +730,12 @@ if not get_option('jack').auto() or have_system
> >    jack = dependency('jack', required: get_option('jack'),
> >                      method: 'pkg-config', kwargs: static_kwargs)
> >  endif
> > +pipewire = not_found
> > +if not get_option('pipewire').auto() or (targetos == 'linux' and
> have_system)
> > +  pipewire = dependency('libpipewire-0.3', version: '>=0.3.60',
> > +                    required: get_option('pipewire'),
> > +                    method: 'pkg-config', kwargs: static_kwargs)
> > +endif
> >  sndio = not_found
> >  if not get_option('sndio').auto() or have_system
> >    sndio = dependency('sndio', required: get_option('sndio'),
> > @@ -1667,6 +1673,7 @@ if have_system
> >      'jack': jack.found(),
> >      'oss': oss.found(),
> >      'pa': pulse.found(),
> > +    'pipewire': pipewire.found(),
> >      'sdl': sdl.found(),
> >      'sndio': sndio.found(),
> >    }
> > @@ -3980,6 +3987,7 @@ if targetos == 'linux'
> >    summary_info += {'ALSA support':    alsa}
> >    summary_info += {'PulseAudio support': pulse}
> >  endif
> > +summary_info += {'Pipewire support':   pipewire}
> >  summary_info += {'JACK support':      jack}
> >  summary_info += {'brlapi support':    brlapi}
> >  summary_info += {'vde support':       vde}
> > diff --git a/meson_options.txt b/meson_options.txt
> > index fc9447d267..9ae1ec7f47 100644
> > --- a/meson_options.txt
> > +++ b/meson_options.txt
> > @@ -21,7 +21,7 @@ option('tls_priority', type : 'string', value :
> 'NORMAL',
> >  option('default_devices', type : 'boolean', value : true,
> >         description: 'Include a default selection of devices in
> emulators')
> >  option('audio_drv_list', type: 'array', value: ['default'],
> > -       choices: ['alsa', 'coreaudio', 'default', 'dsound', 'jack',
> 'oss', 'pa', 'sdl', 'sndio'],
> > +       choices: ['alsa', 'coreaudio', 'default', 'dsound', 'jack',
> 'oss', 'pa', 'pipewire', 'sdl', 'sndio'],
> >         description: 'Set audio driver list')
> >  option('block_drv_rw_whitelist', type : 'string', value : '',
> >         description: 'set block driver read-write whitelist (by default
> affects only QEMU, not tools like qemu-img)')
> > @@ -255,6 +255,8 @@ option('oss', type: 'feature', value: 'auto',
> >         description: 'OSS sound support')
> >  option('pa', type: 'feature', value: 'auto',
> >         description: 'PulseAudio sound support')
> > +option('pipewire', type: 'feature', value: 'auto',
> > +       description: 'Pipewire sound support')
> >  option('sndio', type: 'feature', value: 'auto',
> >         description: 'sndio sound support')
> >
> > diff --git a/qapi/audio.json b/qapi/audio.json
> > index 4e54c00f51..e03396a7bc 100644
> > --- a/qapi/audio.json
> > +++ b/qapi/audio.json
> > @@ -324,6 +324,47 @@
> >      '*out':    'AudiodevPaPerDirectionOptions',
> >      '*server': 'str' } }
> >
> > +##
> > +# @AudiodevPipewirePerDirectionOptions:
> > +#
> > +# Options of the Pipewire backend that are used for both playback and
> > +# recording.
> > +#
> > +# @name: name of the sink/source to use
> > +#
> > +# @stream-name: name of the Pipewire stream created by qemu.  Can be
> > +#               used to identify the stream in Pipewire when you
> > +#               create multiple Pipewire devices or run multiple qemu
> > +#               instances (default: audiodev's id)
> > +#
> > +# @latency: latency you want Pipewire to achieve in microseconds
> > +#           (default 46000)
> > +#
> > +# Since: 8.1
> > +##
> > +{ 'struct': 'AudiodevPipewirePerDirectionOptions',
> > +  'base': 'AudiodevPerDirectionOptions',
> > +  'data': {
> > +    '*name': 'str',
> > +    '*stream-name': 'str',
> > +    '*latency': 'uint32' } }
> > +
> > +##
> > +# @AudiodevPipewireOptions:
> > +#
> > +# Options of the Pipewire audio backend.
> > +#
> > +# @in: options of the capture stream
> > +#
> > +# @out: options of the playback stream
> > +#
> > +# Since: 8.1
> > +##
> > +{ 'struct': 'AudiodevPipewireOptions',
> > +  'data': {
> > +    '*in':     'AudiodevPipewirePerDirectionOptions',
> > +    '*out':    'AudiodevPipewirePerDirectionOptions' } }
> > +
> >  ##
> >  # @AudiodevSdlPerDirectionOptions:
> >  #
> > @@ -416,6 +457,7 @@
> >              { 'name': 'jack', 'if': 'CONFIG_AUDIO_JACK' },
> >              { 'name': 'oss', 'if': 'CONFIG_AUDIO_OSS' },
> >              { 'name': 'pa', 'if': 'CONFIG_AUDIO_PA' },
> > +            { 'name': 'pipewire', 'if': 'CONFIG_AUDIO_PIPEWIRE' },
> >              { 'name': 'sdl', 'if': 'CONFIG_AUDIO_SDL' },
> >              { 'name': 'sndio', 'if': 'CONFIG_AUDIO_SNDIO' },
> >              { 'name': 'spice', 'if': 'CONFIG_SPICE' },
> > @@ -456,6 +498,8 @@
> >                     'if': 'CONFIG_AUDIO_OSS' },
> >      'pa':        { 'type': 'AudiodevPaOptions',
> >                     'if': 'CONFIG_AUDIO_PA' },
> > +    'pipewire':  { 'type': 'AudiodevPipewireOptions',
> > +                   'if': 'CONFIG_AUDIO_PIPEWIRE' },
> >      'sdl':       { 'type': 'AudiodevSdlOptions',
> >                     'if': 'CONFIG_AUDIO_SDL' },
> >      'sndio':     { 'type': 'AudiodevSndioOptions',
> > diff --git a/qemu-options.hx b/qemu-options.hx
> > index 59bdf67a2c..2d908717bd 100644
> > --- a/qemu-options.hx
> > +++ b/qemu-options.hx
> > @@ -779,6 +779,12 @@ DEF("audiodev", HAS_ARG, QEMU_OPTION_audiodev,
> >      "                in|out.name= source/sink device name\n"
> >      "                in|out.latency= desired latency in microseconds\n"
> >  #endif
> > +#ifdef CONFIG_AUDIO_PIPEWIRE
> > +    "-audiodev pipewire,id=id[,prop[=value][,...]]\n"
> > +    "                in|out.name= source/sink device name\n"
> > +    "                in|out.stream-name= name of pipewire stream\n"
> > +    "                in|out.latency= desired latency in microseconds\n"
> > +#endif
> >  #ifdef CONFIG_AUDIO_SDL
> >      "-audiodev sdl,id=id[,prop[=value][,...]]\n"
> >      "                in|out.buffer-count= number of buffers\n"
> > @@ -942,6 +948,21 @@ SRST
> >          Desired latency in microseconds. The PulseAudio server will try
> >          to honor this value but actual latencies may be lower or higher.
> >
> > +``-audiodev pipewire,id=id[,prop[=value][,...]]``
> > +    Creates a backend using Pipewire. This backend is available on
> > +    most systems.
> > +
> > +    Pipewire specific options are:
> > +
> > +    ``in|out.latency=usecs``
> > +        Desired latency in microseconds.
> > +
> > +    ``in|out.name=sink``
> > +        Use the specified source/sink for recording/playback.
> > +
> > +    ``in|out.stream-name``
> > +        Specify the name of pipewire stream.
> > +
> >  ``-audiodev sdl,id=id[,prop[=value][,...]]``
> >      Creates a backend using SDL. This backend is available on most
> >      systems, but you should use your platform's native backend if
> > diff --git a/scripts/meson-buildoptions.sh
> b/scripts/meson-buildoptions.sh
> > index 009fab1515..ba1057b62c 100644
> > --- a/scripts/meson-buildoptions.sh
> > +++ b/scripts/meson-buildoptions.sh
> > @@ -1,7 +1,8 @@
> >  # This file is generated by meson-buildoptions.py, do not edit!
> >  meson_options_help() {
> > -  printf "%s\n" '  --audio-drv-list=CHOICES Set audio driver list
> [default] (choices: alsa/co'
> > -  printf "%s\n" '
>  reaudio/default/dsound/jack/oss/pa/sdl/sndio)'
> > +  printf "%s\n" '  --audio-drv-list=CHOICES Set audio driver list
> [default] (choices: al'
> > +  printf "%s\n" '
>  sa/coreaudio/default/dsound/jack/oss/pa/'
> > +  printf "%s\n" '                           pipewire/sdl/sndio)'
> >    printf "%s\n" '  --block-drv-ro-whitelist=VALUE'
> >    printf "%s\n" '                           set block driver read-only
> whitelist (by default'
> >    printf "%s\n" '                           affects only QEMU, not
> tools like qemu-img)'
> > @@ -136,6 +137,7 @@ meson_options_help() {
> >    printf "%s\n" '  oss             OSS sound support'
> >    printf "%s\n" '  pa              PulseAudio sound support'
> >    printf "%s\n" '  parallels       parallels image format support'
> > +  printf "%s\n" '  pipewire        Pipewire sound support'
> >    printf "%s\n" '  png             PNG support with libpng'
> >    printf "%s\n" '  pvrdma          Enable PVRDMA support'
> >    printf "%s\n" '  qcow1           qcow1 image format support'
> > @@ -370,6 +372,8 @@ _meson_option_parse() {
> >      --disable-pa) printf "%s" -Dpa=disabled ;;
> >      --enable-parallels) printf "%s" -Dparallels=enabled ;;
> >      --disable-parallels) printf "%s" -Dparallels=disabled ;;
> > +    --enable-pipewire) printf "%s" -Dpipewire=enabled ;;
> > +    --disable-pipewire) printf "%s" -Dpipewire=disabled ;;
> >      --with-pkgversion=*) quote_sh "-Dpkgversion=$2" ;;
> >      --enable-png) printf "%s" -Dpng=enabled ;;
> >      --disable-png) printf "%s" -Dpng=disabled ;;
> > --
> > 2.39.1
> >
>
>
> --
> Marc-André Lureau
>
>