| Message ID | 20230502115010.986325-5-perex@perex.cz (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | pcm: hw: implement explicit silencing for snd_pcm_drain | expand |
On Tue, May 02, 2023 at 01:50:10PM +0200, Jaroslav Kysela wrote: >The application may not require to touch the sample stream >for the drain operation at all. Handle this situation >in alsa-lib. > i find this too vague. This allows an application which uses an mmapped buffer to inform us that it is handling the silence padding itself. >Signed-off-by: Jaroslav Kysela <perex@perex.cz> >--- > include/sound/uapi/asound.h | 3 +++ > src/pcm/pcm.c | 32 ++++++++++++++++++++++++++++++++ > src/pcm/pcm_hw.c | 3 ++- > src/pcm/pcm_local.h | 1 + > 4 files changed, 38 insertions(+), 1 deletion(-) > >diff --git a/include/sound/uapi/asound.h b/include/sound/uapi/asound.h >index 0b8834f2..f970179e 100644 >--- a/include/sound/uapi/asound.h >+++ b/include/sound/uapi/asound.h >@@ -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) /* supress drain with the filling >+ * of the silence samples >+ */ "suppress automatic silence fill when draining playback" >--- a/src/pcm/pcm.c >+++ b/src/pcm/pcm.c >@@ -4958,6 +4958,38 @@ 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 allow the drain with the >filling of silence samples > there is no way i'd understand what this means. in fact, i'm having a hard time even though i more or less know it already. >+ * \param pcm PCM handle >+ * \param params Configuration space >+ * \param val 0 = disable, 1 = enable (default) drain with the filling of silence samples > "padding the playback buffer with silence when drain() is invoked" >+ * \return 0 otherwise a negative error code add description: "When disabled, the application must ensure that enough samples are silenced, as most hardware will read beyond the application pointer when drain() is invoked." >+/** >+ * \brief Extract drain with the filling of silence samples from a configuration space > this is also kinda incomprehensible. >+ * \param pcm PCM handle >+ * \param params Configuration space >+ * \param val 0 = disable, 1 = enable > as this returns the status quo, this should be disabled/enabled. >+ * \return 0 otherwise a negative error code > there is no "otherwise" here. >+ */ >+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; > i know i'm paranoid, but i'd put extra parens around the condition. >+ return 0; >+} >+ >--- a/src/pcm/pcm_hw.c >+++ b/src/pcm/pcm_hw.c >@@ -399,7 +399,8 @@ static int snd_pcm_hw_hw_params(snd_pcm_t *pcm, snd_pcm_hw_params_t * params) >- 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); > pedantically, you can remove the double negations as this point. regards
diff --git a/include/sound/uapi/asound.h b/include/sound/uapi/asound.h index 0b8834f2..f970179e 100644 --- a/include/sound/uapi/asound.h +++ b/include/sound/uapi/asound.h @@ -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) /* supress drain with the filling + * of the silence samples + */ struct snd_interval { unsigned int min, max; diff --git a/src/pcm/pcm.c b/src/pcm/pcm.c index 099d83ee..5872ee6f 100644 --- a/src/pcm/pcm.c +++ b/src/pcm/pcm.c @@ -4958,6 +4958,38 @@ 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 allow the drain with the filling of silence samples + * \param pcm PCM handle + * \param params Configuration space + * \param val 0 = disable, 1 = enable (default) drain with the filling of silence samples + * \return 0 otherwise a negative error code + */ +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 = disable, 1 = enable + * \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 diff --git a/src/pcm/pcm_hw.c b/src/pcm/pcm_hw.c index ea0c2ef2..90d5d07a 100644 --- a/src/pcm/pcm_hw.c +++ b/src/pcm/pcm_hw.c @@ -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); } diff --git a/src/pcm/pcm_local.h b/src/pcm/pcm_local.h index b039dda0..abea6654 100644 --- a/src/pcm/pcm_local.h +++ b/src/pcm/pcm_local.h @@ -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
The application may not require to touch the sample stream for the drain operation at all. Handle this situation in alsa-lib. Signed-off-by: Jaroslav Kysela <perex@perex.cz> --- include/sound/uapi/asound.h | 3 +++ src/pcm/pcm.c | 32 ++++++++++++++++++++++++++++++++ src/pcm/pcm_hw.c | 3 ++- src/pcm/pcm_local.h | 1 + 4 files changed, 38 insertions(+), 1 deletion(-)