[v1] pulseaudio: process audio data in smaller chunks

[Qemu-devel] [PATCH] pulseaudio: process audio data in smaller chunks

Gerd Hoffmann posted 1 patch 7 years, 4 months ago

Diff against v2
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git fetch https://github.com/patchew-project/qemu tags/patchew/20180703121924.11411-1-kraxel@redhat.com

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audio/paaudio.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

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[Qemu-devel] [PATCH] pulseaudio: process audio data in smaller chunks

Posted by Gerd Hoffmann 7 years, 4 months ago

The rate of pulseaudio absorbing the audio stream is used to control the
the rate of the guests audio stream.  When the emulated hardware uses
small chunks (like intel-hda does) we need small chunks on the audio
backend side too, otherwise that feedback loop doesn't work very well.

Cc: Max Ehrlich <maxehr@umiacs.umd.edu>
Cc: Martin Schrodt <martin@schrodt.org>
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
---
 audio/paaudio.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/audio/paaudio.c b/audio/paaudio.c
index 949769774d..4c100bc318 100644
--- a/audio/paaudio.c
+++ b/audio/paaudio.c
@@ -227,7 +227,7 @@ static void *qpa_thread_out (void *arg)
             }
         }
 
-        decr = to_mix = audio_MIN (pa->live, pa->g->conf.samples >> 2);
+        decr = to_mix = audio_MIN(pa->live, pa->g->conf.samples >> 5);
         rpos = pa->rpos;
 
         if (audio_pt_unlock(&pa->pt, __func__)) {
@@ -319,7 +319,7 @@ static void *qpa_thread_in (void *arg)
             }
         }
 
-        incr = to_grab = audio_MIN (pa->dead, pa->g->conf.samples >> 2);
+        incr = to_grab = audio_MIN(pa->dead, pa->g->conf.samples >> 5);
         wpos = pa->wpos;
 
         if (audio_pt_unlock(&pa->pt, __func__)) {
-- 
2.9.3

Re: [Qemu-devel] [PATCH] pulseaudio: process audio data in smaller chunks

Posted by Philippe Mathieu-Daudé 7 years, 4 months ago

On 07/03/2018 09:19 AM, Gerd Hoffmann wrote:
> The rate of pulseaudio absorbing the audio stream is used to control the
> the rate of the guests audio stream.  When the emulated hardware uses
> small chunks (like intel-hda does) we need small chunks on the audio
> backend side too, otherwise that feedback loop doesn't work very well.
> 
> Cc: Max Ehrlich <maxehr@umiacs.umd.edu>
> Cc: Martin Schrodt <martin@schrodt.org>
> Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
> ---
>  audio/paaudio.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/audio/paaudio.c b/audio/paaudio.c
> index 949769774d..4c100bc318 100644
> --- a/audio/paaudio.c
> +++ b/audio/paaudio.c
> @@ -227,7 +227,7 @@ static void *qpa_thread_out (void *arg)
>              }
>          }
>  
> -        decr = to_mix = audio_MIN (pa->live, pa->g->conf.samples >> 2);
> +        decr = to_mix = audio_MIN(pa->live, pa->g->conf.samples >> 5);
>          rpos = pa->rpos;
>  
>          if (audio_pt_unlock(&pa->pt, __func__)) {
> @@ -319,7 +319,7 @@ static void *qpa_thread_in (void *arg)
>              }
>          }
>  
> -        incr = to_grab = audio_MIN (pa->dead, pa->g->conf.samples >> 2);
> +        incr = to_grab = audio_MIN(pa->dead, pa->g->conf.samples >> 5);

Same pattern/value: can we have a #define?

I looked at the PA intel-hda code and couldn't find the chunk size,
anyway this change looks sane.

>          wpos = pa->wpos;
>  
>          if (audio_pt_unlock(&pa->pt, __func__)) {
>