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pcm: plugin - fix avail_min calculation on rate plugin

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commit 88e4ae27, ff1f669d introduced a dynamic recalculation of the slave's
avail_min value.
The calculated avail_min setting did not take into account, that the avail_min value
depends on the used sampling rate and must be adapted accordingly
if the slave is using a different sampling rate.
That leads to too large/too small calculated avail_min settings and inaccurate
period wake-up events if a rate converter plugin is used.

This patch is adapting the avail_min calculation to consider a different
sampling rate between actual pcm and it's slave.

Fixes: https://github.com/alsa-project/alsa-lib/pull/218
Signed-off-by: Andreas Pape <apape@de.adit-jv.com>
Signed-off-by: Jaroslav Kysela <perex@perex.cz>
This commit is contained in:
Andreas Pape 2022-03-22 12:45:37 +01:00 • committed by Jaroslav Kysela
parent ea15c83525
commit d21e0e01c6
3 changed files with 31 additions and 0 deletions
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8
src/pcm/pcm_plugin.c
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@ -614,6 +614,14 @@ int snd_pcm_plugin_may_wait_for_avail_min(snd_pcm_t *pcm,
return 0;
needed_slave_avail_min = pcm->avail_min - available;
/* proportional adaption if rate converter is in place..
* Can happen only on built-in rate plugin.
* This code is also used by extplug, but extplug does not allow to alter the sampling rate.
*/
if (snd_pcm_type(pcm) == SND_PCM_TYPE_RATE)
needed_slave_avail_min = snd_pcm_rate_slave_frames(pcm, needed_slave_avail_min);
if (slave->avail_min != needed_slave_avail_min) {
snd_pcm_sw_params_t *swparams;
snd_pcm_sw_params_alloca(&swparams);