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pcm: hw: introduce SNDRV_PCM_HW_PARAMS_DRAIN_SILENCE

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The application may not require to touch the playback
sample stream for the drain operation at all. In this case,
the application is responsible to setup a silencing mechanism
for the playback or another graceful stop (like using the
rewind operation).

Signed-off-by: Jaroslav Kysela <perex@perex.cz>
This commit is contained in:
Jaroslav Kysela 2023-05-02 10:34:41 +02:00
parent 90e25887d2
commit 264d6c43ee
5 changed files with 45 additions and 1 deletions
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2
include/pcm.h
View file

@ -822,6 +822,8 @@ int snd_pcm_hw_params_set_export_buffer(snd_pcm_t *pcm, snd_pcm_hw_params_t *par
int snd_pcm_hw_params_get_export_buffer(snd_pcm_t *pcm, snd_pcm_hw_params_t *params, unsigned int *val);
int snd_pcm_hw_params_set_period_wakeup(snd_pcm_t *pcm, snd_pcm_hw_params_t *params, unsigned int val);
int snd_pcm_hw_params_get_period_wakeup(snd_pcm_t *pcm, snd_pcm_hw_params_t *params, unsigned int *val);
int snd_pcm_hw_params_set_drain_silence(snd_pcm_t *pcm, snd_pcm_hw_params_t *params, unsigned int val);
int snd_pcm_hw_params_get_drain_silence(snd_pcm_t *pcm, snd_pcm_hw_params_t *params, unsigned int *val);
int snd_pcm_hw_params_get_period_time(const snd_pcm_hw_params_t *params, unsigned int *val, int *dir);
int snd_pcm_hw_params_get_period_time_min(const snd_pcm_hw_params_t *params, unsigned int *val, int *dir);

3
include/sound/uapi/asound.h
View file

@ -390,6 +390,9 @@ typedef int snd_pcm_hw_param_t;
#define SNDRV_PCM_HW_PARAMS_NORESAMPLE (1<<0) /* avoid rate resampling */
#define SNDRV_PCM_HW_PARAMS_EXPORT_BUFFER (1<<1) /* export buffer */
#define SNDRV_PCM_HW_PARAMS_NO_PERIOD_WAKEUP (1<<2) /* disable period wakeups */
#define SNDRV_PCM_HW_PARAMS_NO_DRAIN_SILENCE (1<<3) /* suppress the silence fill
* for draining
*/
struct snd_interval {
unsigned int min, max;

37
src/pcm/pcm.c
View file

@ -4958,6 +4958,43 @@ int snd_pcm_hw_params_get_period_wakeup(snd_pcm_t *pcm, snd_pcm_hw_params_t *par
return 0;
}
/**
* \brief Restrict a configuration space to fill the end of playback stream with silence when drain() is invoked
* \param pcm PCM handle
* \param params Configuration space
* \param val 0 = disabled, 1 = enabled (default) fill the end of the playback stream with silence when drain() is invoked
* \return Zero on success, otherwise a negative error code.
*
* When disabled, the application should handle the end of stream gracefully
* (fill the silent samples to align to the period size plus some extra
* samples for hardware / driver without perfect drain). Note that the rewind
* may be used for this purpose or the sw_params silencing mechanism.
*/
int snd_pcm_hw_params_set_drain_silence(snd_pcm_t *pcm, snd_pcm_hw_params_t *params, unsigned int val)
{
assert(pcm && params);
if (val)
params->flags &= ~SND_PCM_HW_PARAMS_NO_DRAIN_SILENCE;
else
params->flags |= SND_PCM_HW_PARAMS_NO_DRAIN_SILENCE;
params->rmask = ~0;
return snd_pcm_hw_refine(pcm, params);
}
/**
* \brief Extract drain with the filling of silence samples from a configuration space
* \param pcm PCM handle
* \param params Configuration space
* \param val 0 = disabled, 1 = enabled
* \return 0 otherwise a negative error code
*/
int snd_pcm_hw_params_get_drain_silence(snd_pcm_t *pcm, snd_pcm_hw_params_t *params, unsigned int *val)
{
assert(pcm && params && val);
*val = params->flags & SND_PCM_HW_PARAMS_NO_DRAIN_SILENCE ? 0 : 1;
return 0;
}
/**
* \brief Extract period time from a configuration space
* \param params Configuration space

3
src/pcm/pcm_hw.c
View file

@ -399,7 +399,8 @@ static int snd_pcm_hw_hw_params(snd_pcm_t *pcm, snd_pcm_hw_params_t * params)
params->info &= ~0xf0000000;
if (pcm->tstamp_type != SND_PCM_TSTAMP_TYPE_GETTIMEOFDAY)
params->info |= SND_PCM_INFO_MONOTONIC;
hw->perfect_drain = !!(params->info & SND_PCM_INFO_PERFECT_DRAIN);
hw->perfect_drain = !!(params->info & SND_PCM_INFO_PERFECT_DRAIN) ||
!!(params->flags & SND_PCM_HW_PARAMS_NO_DRAIN_SILENCE);
return query_status_data(hw);
}

1
src/pcm/pcm_local.h
View file

@ -107,6 +107,7 @@
#define SND_PCM_HW_PARAMS_NORESAMPLE SNDRV_PCM_HW_PARAMS_NORESAMPLE
#define SND_PCM_HW_PARAMS_EXPORT_BUFFER SNDRV_PCM_HW_PARAMS_EXPORT_BUFFER
#define SND_PCM_HW_PARAMS_NO_PERIOD_WAKEUP SNDRV_PCM_HW_PARAMS_NO_PERIOD_WAKEUP
#define SND_PCM_HW_PARAMS_NO_DRAIN_SILENCE SNDRV_PCM_HW_PARAMS_NO_DRAIN_SILENCE
#define SND_PCM_INFO_MONOTONIC 0x80000000