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Set ALSA playback buffer and period size based on time

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So rate adjustments won't modify the latency
This commit is contained in:
Chris Robinson 2010-02-08 17:42:44 -08:00
parent a329f9c84a
commit 96303893bc
1 changed files with 13 additions and 9 deletions
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22
Alc/alsa.c
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@ -68,6 +68,8 @@ MAKE_FUNC(snd_pcm_hw_params_set_periods_near);
MAKE_FUNC(snd_pcm_hw_params_set_rate_near);
MAKE_FUNC(snd_pcm_hw_params_set_rate);
MAKE_FUNC(snd_pcm_hw_params_set_rate_resample);
MAKE_FUNC(snd_pcm_hw_params_set_buffer_time_near);
MAKE_FUNC(snd_pcm_hw_params_set_period_time_near);
MAKE_FUNC(snd_pcm_hw_params_set_buffer_size_near);
MAKE_FUNC(snd_pcm_hw_params_set_period_size_near);
MAKE_FUNC(snd_pcm_hw_params_set_buffer_size_min);
@ -163,6 +165,8 @@ LOAD_FUNC(snd_pcm_hw_params_set_periods_near);
LOAD_FUNC(snd_pcm_hw_params_set_rate_near);
LOAD_FUNC(snd_pcm_hw_params_set_rate);
LOAD_FUNC(snd_pcm_hw_params_set_rate_resample);
LOAD_FUNC(snd_pcm_hw_params_set_buffer_time_near);
LOAD_FUNC(snd_pcm_hw_params_set_period_time_near);
LOAD_FUNC(snd_pcm_hw_params_set_buffer_size_near);
LOAD_FUNC(snd_pcm_hw_params_set_buffer_size_min);
LOAD_FUNC(snd_pcm_hw_params_set_period_size_near);
@ -512,7 +516,7 @@ static ALCboolean alsa_reset_playback(ALCdevice *device)
{
alsa_data *data = (alsa_data*)device->ExtraData;
snd_pcm_uframes_t periodSizeInFrames;
snd_pcm_uframes_t bufferSizeInFrames;
unsigned int periodLen, bufferLen;
snd_pcm_sw_params_t *sp = NULL;
snd_pcm_hw_params_t *p = NULL;
snd_pcm_access_t access;
@ -542,7 +546,7 @@ static ALCboolean alsa_reset_playback(ALCdevice *device)
allowmmap = GetConfigValueBool("alsa", "mmap", 1);
periods = device->NumUpdates;
periodSizeInFrames = device->UpdateSize;
periodLen = (ALuint64)device->UpdateSize * 1000000 / device->Frequency;
rate = device->Frequency;
err = NULL;
@ -625,13 +629,13 @@ static ALCboolean alsa_reset_playback(ALCdevice *device)
/* set rate (implicitly constrains period/buffer parameters) */
if(i >= 0 && (i=psnd_pcm_hw_params_set_rate_near(data->pcmHandle, p, &rate, NULL)) < 0)
err = "set rate near";
/* set buffer size (implicitly constrains period/buffer parameters) */
bufferSizeInFrames = periodSizeInFrames * periods;
if(i >= 0 && (i=psnd_pcm_hw_params_set_buffer_size_near(data->pcmHandle, p, &bufferSizeInFrames)) < 0)
err = "set buffer size near";
/* set period size in frame units (implicitly sets buffer size/bytes/time and period time/bytes) */
if(i >= 0 && (i=psnd_pcm_hw_params_set_period_size_near(data->pcmHandle, p, &periodSizeInFrames, NULL)) < 0)
err = "set period size near";
/* set buffer time (implicitly constrains period/buffer parameters) */
bufferLen = periodLen * periods;
if(i >= 0 && (i=psnd_pcm_hw_params_set_buffer_time_near(data->pcmHandle, p, &bufferLen, NULL)) < 0)
err = "set buffer time near";
/* set period time in frame units (implicitly sets buffer size/bytes/time and period size/bytes) */
if(i >= 0 && (i=psnd_pcm_hw_params_set_period_time_near(data->pcmHandle, p, &periodLen, NULL)) < 0)
err = "set period time near";
/* install and prepare hardware configuration */
if(i >= 0 && (i=psnd_pcm_hw_params(data->pcmHandle, p)) < 0)
err = "set params";