snd_pcm_start_at() - alsa-lib

The headlines:

- Provide userspace snd_pcm_start_at, leverage new ioctl - Provide some decent doxygen guff

diff --git a/include/pcm.h b/include/pcm.h index 0655e7f..bbe6e79 100644 --- a/include/pcm.h +++ b/include/pcm.h @@ -325,9 +325,10 @@ typedef enum _snd_pcm_tstamp {

typedef enum _snd_pcm_tstamp_type { SND_PCM_TSTAMP_TYPE_GETTIMEOFDAY = 0, /** gettimeofday equivalent */ - SND_PCM_TSTAMP_TYPE_MONOTONIC, /** posix_clock_monotonic equivalent */ + SND_PCM_TSTAMP_TYPE_MONOTONIC, /** posix_clock_monotonic equivalent */ SND_PCM_TSTAMP_TYPE_MONOTONIC_RAW, /** monotonic_raw (no NTP) */ - SND_PCM_TSTAMP_TYPE_LAST = SND_PCM_TSTAMP_TYPE_MONOTONIC_RAW, + SND_PCM_TSTAMP_TYPE_AUDIO_WALLCLOCK, /** audio hw clock */ + SND_PCM_TSTAMP_TYPE_LAST = SND_PCM_TSTAMP_TYPE_AUDIO_WALLCLOCK, } snd_pcm_tstamp_type_t;

/** Unsigned frames quantity */ @@ -478,6 +479,7 @@ int snd_pcm_prepare(snd_pcm_t *pcm); int snd_pcm_reset(snd_pcm_t *pcm); int snd_pcm_status(snd_pcm_t *pcm, snd_pcm_status_t *status); int snd_pcm_start(snd_pcm_t *pcm); +int snd_pcm_start_at(snd_pcm_t *pcm, const snd_htimestamp_t* start_time); int snd_pcm_drop(snd_pcm_t *pcm); int snd_pcm_drain(snd_pcm_t *pcm); int snd_pcm_pause(snd_pcm_t *pcm, int enable); diff --git a/include/sound/asound.h b/include/sound/asound.h index 941d32f..bcc49dc 100644 --- a/include/sound/asound.h +++ b/include/sound/asound.h @@ -467,8 +467,9 @@ struct snd_xfern { enum { SNDRV_PCM_TSTAMP_TYPE_GETTIMEOFDAY = 0, /* gettimeofday equivalent */ SNDRV_PCM_TSTAMP_TYPE_MONOTONIC, /* posix_clock_monotonic equivalent */ - SNDRV_PCM_TSTAMP_TYPE_MONOTONIC_RAW, /* monotonic_raw (no NTP) */ - SNDRV_PCM_TSTAMP_TYPE_LAST = SNDRV_PCM_TSTAMP_TYPE_MONOTONIC_RAW, + SNDRV_PCM_TSTAMP_TYPE_MONOTONIC_RAW, /* monotonic_raw (no NTP) */ + SNDRV_PCM_TSTAMP_TYPE_AUDIO_WALLCLOCK, /* audio hw clock */ + SNDRV_PCM_TSTAMP_TYPE_LAST = SNDRV_PCM_TSTAMP_TYPE_AUDIO_WALLCLOCK, };

/* channel positions */ @@ -549,6 +550,8 @@ enum { #define SNDRV_PCM_IOCTL_READN_FRAMES _IOR('A', 0x53, struct snd_xfern) #define SNDRV_PCM_IOCTL_LINK _IOW('A', 0x60, int) #define SNDRV_PCM_IOCTL_UNLINK _IO('A', 0x61) +#define SNDRV_PCM_IOCTL_START_AT _IOW('A', 0x62, snd_htimestamp_t) +

/***************************************************************************** * * diff --git a/src/pcm/pcm.c b/src/pcm/pcm.c index baa47c7..61158cb 100644 --- a/src/pcm/pcm.c +++ b/src/pcm/pcm.c @@ -1085,6 +1085,38 @@ int snd_pcm_start(snd_pcm_t *pcm) }

/** + * \brief Start a PCM at a specified point in the future + * \param pcm PCM handle + * \param start_time Absolute time at which to start the stream + * \return 0 on success otherwise a negative error code + * \retval -ENOSYS operation not supported for the current timestamp type + * \retval -EINVAL timespec invalid + * \retval -ETIME requested start_time cannot be satisfied + * + * This method is non-blocking: It establishes an appropriate timer in the kernel + * that will start the stream on expiry. + * + * The timer is unconditionally cancelled upon any \a attempt to change the stream + * state e.g. drop, drain, start, start_at. + * + * \p start_time is interpreted in the context of the stream snd_pcm_tstamp_type, + * set using \link ::snd_pcm_sw_params_set_tstamp_type() \endlink. + */ +int snd_pcm_start_at(snd_pcm_t *pcm, const snd_htimestamp_t *start_time) +{ + assert(pcm); + assert(start_time); + if (CHECK_SANITY(! pcm->setup)) { + SNDMSG("PCM not set up"); + return -EIO; + } + if (pcm->fast_ops->start_at) { + return pcm->fast_ops->start_at(pcm->fast_op_arg, start_time); + } + return -EINVAL; +} + +/** * \brief Stop a PCM dropping pending frames * \param pcm PCM handle * \return 0 on success otherwise a negative error code @@ -1693,6 +1725,7 @@ static const char *const snd_pcm_tstamp_type_names[] = { TSTAMP_TYPE(GETTIMEOFDAY), TSTAMP_TYPE(MONOTONIC), TSTAMP_TYPE(MONOTONIC_RAW), + TSTAMP_TYPE(AUDIO_WALLCLOCK), }; #endif

diff --git a/src/pcm/pcm_hw.c b/src/pcm/pcm_hw.c index c34b766..aa0c7ba 100644 --- a/src/pcm/pcm_hw.c +++ b/src/pcm/pcm_hw.c @@ -447,6 +447,11 @@ static int snd_pcm_hw_sw_params(snd_pcm_t *pcm, snd_pcm_sw_params_t * params) hw->mmap_control->avail_min = params->avail_min; return sync_ptr(hw, 0); } + if (params->tstamp_type == SND_PCM_TSTAMP_TYPE_AUDIO_WALLCLOCK && + hw->version < SNDRV_PROTOCOL_VERSION(2, 0, 12)) { + SYSMSG("Kernel doesn't support SND_PCM_TSTAMP_TYPE_AUDIO_WALLCLOCK"); + return -EINVAL; + } if (params->tstamp_type == SND_PCM_TSTAMP_TYPE_MONOTONIC_RAW && hw->version < SNDRV_PROTOCOL_VERSION(2, 0, 12)) { SYSMSG("Kernel doesn't support SND_PCM_TSTAMP_TYPE_MONOTONIC_RAW"); @@ -620,6 +625,20 @@ static int snd_pcm_hw_start(snd_pcm_t *pcm) return 0; }

+static int snd_pcm_hw_start_at(snd_pcm_t *pcm, const snd_htimestamp_t *start_time) +{ + snd_pcm_hw_t *hw = pcm->private_data; + int err; + + sync_ptr(hw, 0); + if (ioctl(hw->fd, SNDRV_PCM_IOCTL_START_AT, start_time) < 0) { + err = -errno; + SYSMSG("SNDRV_PCM_IOCTL_START_AT failed (%i)", err); + return err; + } + return 0; +} + static int snd_pcm_hw_drop(snd_pcm_t *pcm) { snd_pcm_hw_t *hw = pcm->private_data; @@ -1336,6 +1355,7 @@ static const snd_pcm_fast_ops_t snd_pcm_hw_fast_ops = { .prepare = snd_pcm_hw_prepare, .reset = snd_pcm_hw_reset, .start = snd_pcm_hw_start, + .start_at = snd_pcm_hw_start_at, .drop = snd_pcm_hw_drop, .drain = snd_pcm_hw_drain, .pause = snd_pcm_hw_pause, diff --git a/src/pcm/pcm_local.h b/src/pcm/pcm_local.h index 394505f..6829750 100644 --- a/src/pcm/pcm_local.h +++ b/src/pcm/pcm_local.h @@ -154,6 +154,7 @@ typedef struct { int (*prepare)(snd_pcm_t *pcm); int (*reset)(snd_pcm_t *pcm); int (*start)(snd_pcm_t *pcm); + int (*start_at)(snd_pcm_t *pcm, const snd_htimestamp_t *start_time); int (*drop)(snd_pcm_t *pcm); int (*drain)(snd_pcm_t *pcm); int (*pause)(snd_pcm_t *pcm, int enable);