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[Qemu-devel] [PATCH 1/3] pulseaudio: process 1/4 buffer max at once
From: |
Gerd Hoffmann |
Subject: |
[Qemu-devel] [PATCH 1/3] pulseaudio: process 1/4 buffer max at once |
Date: |
Fri, 29 Oct 2010 14:55:53 +0200 |
Limit the size of data pieces processed by the pulseaudio worker
threads. Never ever process more than 1/4 of the buffer at once.
Background: The buffer area currently processed by the pulseaudio thread
is blocked, i.e. the main thread (or iothread) can't fill in more data
there. The buffer processing time is roughly real-time due to the
pa_simple_write() call blocking when the output queue to the pulse
server is full. Thus processing big chunks at once means blocking
a large part of the buffer for a long time. This brings high latency
and can lead to dropouts.
When processing the buffer in smaller chunks the rpos handling becomes a
problem though. The thread reads hw->rpos without knowing whenever
qpa_run_out has already seen the last (small) chunk processed and
updated rpos accordingly. There is no point in reading hw->rpos though,
pa->rpos can be used instead. We just need to take care to initialize
pa->rpos before kicking the thread.
Signed-off-by: Gerd Hoffmann <address@hidden>
---
audio/paaudio.c | 22 +++++++++-------------
1 files changed, 9 insertions(+), 13 deletions(-)
diff --git a/audio/paaudio.c b/audio/paaudio.c
index ff71dac..f99ca73 100644
--- a/audio/paaudio.c
+++ b/audio/paaudio.c
@@ -57,9 +57,6 @@ static void *qpa_thread_out (void *arg)
{
PAVoiceOut *pa = arg;
HWVoiceOut *hw = &pa->hw;
- int threshold;
-
- threshold = conf.divisor ? hw->samples / conf.divisor : 0;
if (audio_pt_lock (&pa->pt, AUDIO_FUNC)) {
return NULL;
@@ -73,7 +70,7 @@ static void *qpa_thread_out (void *arg)
goto exit;
}
- if (pa->live > threshold) {
+ if (pa->live > 0) {
break;
}
@@ -82,8 +79,8 @@ static void *qpa_thread_out (void *arg)
}
}
- decr = to_mix = pa->live;
- rpos = hw->rpos;
+ decr = to_mix = audio_MIN (pa->live, conf.samples >> 2);
+ rpos = pa->rpos;
if (audio_pt_unlock (&pa->pt, AUDIO_FUNC)) {
return NULL;
@@ -110,8 +107,8 @@ static void *qpa_thread_out (void *arg)
return NULL;
}
- pa->live = 0;
pa->rpos = rpos;
+ pa->live -= decr;
pa->decr += decr;
}
@@ -152,9 +149,6 @@ static void *qpa_thread_in (void *arg)
{
PAVoiceIn *pa = arg;
HWVoiceIn *hw = &pa->hw;
- int threshold;
-
- threshold = conf.divisor ? hw->samples / conf.divisor : 0;
if (audio_pt_lock (&pa->pt, AUDIO_FUNC)) {
return NULL;
@@ -168,7 +162,7 @@ static void *qpa_thread_in (void *arg)
goto exit;
}
- if (pa->dead > threshold) {
+ if (pa->dead > 0) {
break;
}
@@ -177,8 +171,8 @@ static void *qpa_thread_in (void *arg)
}
}
- incr = to_grab = pa->dead;
- wpos = hw->wpos;
+ incr = to_grab = audio_MIN (pa->dead, conf.samples >> 2);
+ wpos = pa->wpos;
if (audio_pt_unlock (&pa->pt, AUDIO_FUNC)) {
return NULL;
@@ -323,6 +317,7 @@ static int qpa_init_out (HWVoiceOut *hw, struct audsettings
*as)
audio_pcm_init_info (&hw->info, &obt_as);
hw->samples = conf.samples;
pa->pcm_buf = audio_calloc (AUDIO_FUNC, hw->samples, 1 << hw->info.shift);
+ pa->rpos = hw->rpos;
if (!pa->pcm_buf) {
dolog ("Could not allocate buffer (%d bytes)\n",
hw->samples << hw->info.shift);
@@ -377,6 +372,7 @@ static int qpa_init_in (HWVoiceIn *hw, struct audsettings
*as)
audio_pcm_init_info (&hw->info, &obt_as);
hw->samples = conf.samples;
pa->pcm_buf = audio_calloc (AUDIO_FUNC, hw->samples, 1 << hw->info.shift);
+ pa->wpos = hw->wpos;
if (!pa->pcm_buf) {
dolog ("Could not allocate buffer (%d bytes)\n",
hw->samples << hw->info.shift);
--
1.7.1