Hardware Parameters

Collaboration diagram for Hardware Parameters:

Macros
#define	snd_pcm_hw_params_alloca(ptr)
	allocate an invalid snd_pcm_hw_params_t using standard alloca More...

Functions
int	snd_pcm_hw_params_any (snd_pcm_t *pcm, snd_pcm_hw_params_t *params)
	Fill params with a full configuration space for a PCM. More...
int	snd_pcm_hw_params_can_mmap_sample_resolution (const snd_pcm_hw_params_t *params)
	Check if hardware supports sample-resolution mmap for given configuration. More...
int	snd_pcm_hw_params_is_double (const snd_pcm_hw_params_t *params)
	Check if hardware does double buffering for start/stop for given configuration. More...
int	snd_pcm_hw_params_is_batch (const snd_pcm_hw_params_t *params)
	Check if hardware does double buffering for data transfers for given configuration. More...
int	snd_pcm_hw_params_is_block_transfer (const snd_pcm_hw_params_t *params)
	Check if hardware does block transfers for samples for given configuration. More...
int	snd_pcm_hw_params_is_monotonic (const snd_pcm_hw_params_t *params)
	Check if timestamps are monotonic for given configuration. More...
int	snd_pcm_hw_params_can_overrange (const snd_pcm_hw_params_t *params)
	Check if hardware supports overrange detection. More...
int	snd_pcm_hw_params_can_pause (const snd_pcm_hw_params_t *params)
	Check if hardware supports pause. More...
int	snd_pcm_hw_params_can_resume (const snd_pcm_hw_params_t *params)
	Check if hardware supports resume. More...
int	snd_pcm_hw_params_is_half_duplex (const snd_pcm_hw_params_t *params)
	Check if hardware does half-duplex only. More...
int	snd_pcm_hw_params_is_joint_duplex (const snd_pcm_hw_params_t *params)
	Check if hardware does joint-duplex (playback and capture are somewhat correlated) More...
int	snd_pcm_hw_params_can_sync_start (const snd_pcm_hw_params_t *params)
	Check if hardware supports synchronized start with sample resolution. More...
int	snd_pcm_hw_params_can_disable_period_wakeup (const snd_pcm_hw_params_t *params)
	Check if hardware can disable period wakeups. More...
int	snd_pcm_hw_params_supports_audio_wallclock_ts (const snd_pcm_hw_params_t *params)
	Check if hardware supports audio wallclock timestamps. More...
int	snd_pcm_hw_params_supports_audio_ts_type (const snd_pcm_hw_params_t *params, int type)
	Check if hardware supports type of audio timestamps. More...
int	snd_pcm_hw_params_get_rate_numden (const snd_pcm_hw_params_t *params, unsigned int *rate_num, unsigned int *rate_den)
	Get rate exact info from a configuration space. More...
int	snd_pcm_hw_params_get_sbits (const snd_pcm_hw_params_t *params)
	Get sample resolution info from a configuration space. More...
int	snd_pcm_hw_params_get_fifo_size (const snd_pcm_hw_params_t *params)
	Get hardware FIFO size info from a configuration space. More...
size_t	snd_pcm_hw_params_sizeof (void)
	get size of snd_pcm_hw_params_t More...
int	snd_pcm_hw_params_malloc (snd_pcm_hw_params_t **ptr)
	allocate an invalid snd_pcm_hw_params_t using standard malloc More...
void	snd_pcm_hw_params_free (snd_pcm_hw_params_t *obj)
	frees a previously allocated snd_pcm_hw_params_t More...
void	snd_pcm_hw_params_copy (snd_pcm_hw_params_t *dst, const snd_pcm_hw_params_t *src)
	copy one snd_pcm_hw_params_t to another More...
int	snd_pcm_hw_params_get_access (const snd_pcm_hw_params_t *params, snd_pcm_access_t *_access)
	Extract access type from a configuration space. More...
int	snd_pcm_hw_params_test_access (snd_pcm_t *pcm, snd_pcm_hw_params_t *params, snd_pcm_access_t _access)
	Verify if an access type is available inside a configuration space for a PCM. More...
int	snd_pcm_hw_params_set_access (snd_pcm_t *pcm, snd_pcm_hw_params_t *params, snd_pcm_access_t _access)
	Restrict a configuration space to contain only one access type. More...
int	snd_pcm_hw_params_set_access_first (snd_pcm_t *pcm, snd_pcm_hw_params_t *params, snd_pcm_access_t *_access)
	Restrict a configuration space to contain only its first access type. More...
int	snd_pcm_hw_params_set_access_last (snd_pcm_t *pcm, snd_pcm_hw_params_t *params, snd_pcm_access_t *_access)
	Restrict a configuration space to contain only its last access type. More...
int	snd_pcm_hw_params_set_access_mask (snd_pcm_t *pcm, snd_pcm_hw_params_t *params, snd_pcm_access_mask_t *mask)
	Restrict a configuration space to contain only a set of access types. More...
int	snd_pcm_hw_params_get_access_mask (snd_pcm_hw_params_t *params, snd_pcm_access_mask_t *mask)
	Get access mask from a configuration space. More...
int	snd_pcm_hw_params_get_format (const snd_pcm_hw_params_t *params, snd_pcm_format_t *val)
	Extract format from a configuration space. More...
int	snd_pcm_hw_params_test_format (snd_pcm_t *pcm, snd_pcm_hw_params_t *params, snd_pcm_format_t val)
	Verify if a format is available inside a configuration space for a PCM. More...
int	snd_pcm_hw_params_set_format (snd_pcm_t *pcm, snd_pcm_hw_params_t *params, snd_pcm_format_t val)
	Restrict a configuration space to contain only one format. More...
int	snd_pcm_hw_params_set_format_first (snd_pcm_t *pcm, snd_pcm_hw_params_t *params, snd_pcm_format_t *format)
	Restrict a configuration space to contain only its first format. More...
int	snd_pcm_hw_params_set_format_last (snd_pcm_t *pcm, snd_pcm_hw_params_t *params, snd_pcm_format_t *format)
	Restrict a configuration space to contain only its last format. More...
int	snd_pcm_hw_params_set_format_mask (snd_pcm_t *pcm, snd_pcm_hw_params_t *params, snd_pcm_format_mask_t *mask)
	Restrict a configuration space to contain only a set of formats. More...
void	snd_pcm_hw_params_get_format_mask (snd_pcm_hw_params_t *params, snd_pcm_format_mask_t *mask)
	Get format mask from a configuration space. More...
int	snd_pcm_hw_params_get_subformat (const snd_pcm_hw_params_t *params, snd_pcm_subformat_t *subformat)
	Extract subformat from a configuration space. More...
int	snd_pcm_hw_params_test_subformat (snd_pcm_t *pcm, snd_pcm_hw_params_t *params, snd_pcm_subformat_t subformat)
	Verify if a subformat is available inside a configuration space for a PCM. More...
int	snd_pcm_hw_params_set_subformat (snd_pcm_t *pcm, snd_pcm_hw_params_t *params, snd_pcm_subformat_t subformat)
	Restrict a configuration space to contain only one subformat. More...
int	snd_pcm_hw_params_set_subformat_first (snd_pcm_t *pcm, snd_pcm_hw_params_t *params, snd_pcm_subformat_t *subformat)
	Restrict a configuration space to contain only its first subformat. More...
int	snd_pcm_hw_params_set_subformat_last (snd_pcm_t *pcm, snd_pcm_hw_params_t *params, snd_pcm_subformat_t *subformat)
	Restrict a configuration space to contain only its last subformat. More...
int	snd_pcm_hw_params_set_subformat_mask (snd_pcm_t *pcm, snd_pcm_hw_params_t *params, snd_pcm_subformat_mask_t *mask)
	Restrict a configuration space to contain only a set of subformats. More...
void	snd_pcm_hw_params_get_subformat_mask (snd_pcm_hw_params_t *params, snd_pcm_subformat_mask_t *mask)
	Get subformat mask from a configuration space. More...
int	snd_pcm_hw_params_get_channels (const snd_pcm_hw_params_t *params, unsigned int *val)
	Extract channels from a configuration space. More...
int	snd_pcm_hw_params_get_channels_min (const snd_pcm_hw_params_t *params, unsigned int *val)
	Extract minimum channels count from a configuration space. More...
int	snd_pcm_hw_params_get_channels_max (const snd_pcm_hw_params_t *params, unsigned int *val)
	Extract maximum channels count from a configuration space. More...
int	snd_pcm_hw_params_test_channels (snd_pcm_t *pcm, snd_pcm_hw_params_t *params, unsigned int val)
	Verify if a channels count is available inside a configuration space for a PCM. More...
int	snd_pcm_hw_params_set_channels (snd_pcm_t *pcm, snd_pcm_hw_params_t *params, unsigned int val)
	Restrict a configuration space to contain only one channels count. More...
int	snd_pcm_hw_params_set_channels_min (snd_pcm_t *pcm, snd_pcm_hw_params_t *params, unsigned int *val)
	Restrict a configuration space with a minimum channels count. More...
int	snd_pcm_hw_params_set_channels_max (snd_pcm_t *pcm, snd_pcm_hw_params_t *params, unsigned int *val)
	Restrict a configuration space with a maximum channels count. More...
int	snd_pcm_hw_params_set_channels_minmax (snd_pcm_t *pcm, snd_pcm_hw_params_t *params, unsigned int *min, unsigned int *max)
	Restrict a configuration space to have channels counts in a given range. More...
int	snd_pcm_hw_params_set_channels_near (snd_pcm_t *pcm, snd_pcm_hw_params_t *params, unsigned int *val)
	Restrict a configuration space to have channels count nearest to a target. More...
int	snd_pcm_hw_params_set_channels_first (snd_pcm_t *pcm, snd_pcm_hw_params_t *params, unsigned int *val)
	Restrict a configuration space to contain only its minimum channels count. More...
int	snd_pcm_hw_params_set_channels_last (snd_pcm_t *pcm, snd_pcm_hw_params_t *params, unsigned int *val)
	Restrict a configuration space to contain only its maximum channels count. More...
int	snd_pcm_hw_params_get_rate (const snd_pcm_hw_params_t *params, unsigned int *val, int *dir)
	Extract rate from a configuration space. More...
int	snd_pcm_hw_params_get_rate_min (const snd_pcm_hw_params_t *params, unsigned int *val, int *dir)
	Extract minimum rate from a configuration space. More...
int	snd_pcm_hw_params_get_rate_max (const snd_pcm_hw_params_t *params, unsigned int *val, int *dir)
	Extract maximum rate from a configuration space. More...
int	snd_pcm_hw_params_test_rate (snd_pcm_t *pcm, snd_pcm_hw_params_t *params, unsigned int val, int dir)
	Verify if a rate is available inside a configuration space for a PCM. More...
int	snd_pcm_hw_params_set_rate (snd_pcm_t *pcm, snd_pcm_hw_params_t *params, unsigned int val, int dir)
	Restrict a configuration space to contain only one rate. More...
int	snd_pcm_hw_params_set_rate_min (snd_pcm_t *pcm, snd_pcm_hw_params_t *params, unsigned int *val, int *dir)
	Restrict a configuration space with a minimum rate. More...
int	snd_pcm_hw_params_set_rate_max (snd_pcm_t *pcm, snd_pcm_hw_params_t *params, unsigned int *val, int *dir)
	Restrict a configuration space with a maximum rate. More...
int	snd_pcm_hw_params_set_rate_minmax (snd_pcm_t *pcm, snd_pcm_hw_params_t *params, unsigned int *min, int *mindir, unsigned int *max, int *maxdir)
	Restrict a configuration space to have rates in a given range. More...
int	snd_pcm_hw_params_set_rate_near (snd_pcm_t *pcm, snd_pcm_hw_params_t *params, unsigned int *val, int *dir)
	Restrict a configuration space to have rate nearest to a target. More...
int	snd_pcm_hw_params_set_rate_first (snd_pcm_t *pcm, snd_pcm_hw_params_t *params, unsigned int *val, int *dir)
	Restrict a configuration space to contain only its minimum rate. More...
int	snd_pcm_hw_params_set_rate_last (snd_pcm_t *pcm, snd_pcm_hw_params_t *params, unsigned int *val, int *dir)
	Restrict a configuration space to contain only its maximum rate. More...
int	snd_pcm_hw_params_set_rate_resample (snd_pcm_t *pcm, snd_pcm_hw_params_t *params, unsigned int val)
	Restrict a configuration space to contain only real hardware rates. More...
int	snd_pcm_hw_params_get_rate_resample (snd_pcm_t *pcm, snd_pcm_hw_params_t *params, unsigned int *val)
	Extract resample state from a configuration space. More...
int	snd_pcm_hw_params_set_export_buffer (snd_pcm_t *pcm, snd_pcm_hw_params_t *params, unsigned int val)
	Restrict a configuration space to allow the buffer to be accessible from outside. More...
int	snd_pcm_hw_params_get_export_buffer (snd_pcm_t *pcm, snd_pcm_hw_params_t *params, unsigned int *val)
	Extract buffer accessibility from a configuration space. More...
int	snd_pcm_hw_params_set_period_wakeup (snd_pcm_t *pcm, snd_pcm_hw_params_t *params, unsigned int val)
	Restrict a configuration space to settings without period wakeups. More...
int	snd_pcm_hw_params_get_period_wakeup (snd_pcm_t *pcm, snd_pcm_hw_params_t *params, unsigned int *val)
	Extract period wakeup flag from a configuration space. More...
int	snd_pcm_hw_params_get_period_time (const snd_pcm_hw_params_t *params, unsigned int *val, int *dir)
	Extract period time from a configuration space. More...
int	snd_pcm_hw_params_get_period_time_min (const snd_pcm_hw_params_t *params, unsigned int *val, int *dir)
	Extract minimum period time from a configuration space. More...
int	snd_pcm_hw_params_get_period_time_max (const snd_pcm_hw_params_t *params, unsigned int *val, int *dir)
	Extract maximum period time from a configuration space. More...
int	snd_pcm_hw_params_test_period_time (snd_pcm_t *pcm, snd_pcm_hw_params_t *params, unsigned int val, int dir)
	Verify if a period time is available inside a configuration space for a PCM. More...
int	snd_pcm_hw_params_set_period_time (snd_pcm_t *pcm, snd_pcm_hw_params_t *params, unsigned int val, int dir)
	Restrict a configuration space to contain only one period time. More...
int	snd_pcm_hw_params_set_period_time_min (snd_pcm_t *pcm, snd_pcm_hw_params_t *params, unsigned int *val, int *dir)
	Restrict a configuration space with a minimum period time. More...
int	snd_pcm_hw_params_set_period_time_max (snd_pcm_t *pcm, snd_pcm_hw_params_t *params, unsigned int *val, int *dir)
	Restrict a configuration space with a maximum period time. More...
int	snd_pcm_hw_params_set_period_time_minmax (snd_pcm_t *pcm, snd_pcm_hw_params_t *params, unsigned int *min, int *mindir, unsigned int *max, int *maxdir)
	Restrict a configuration space to have period times in a given range. More...
int	snd_pcm_hw_params_set_period_time_near (snd_pcm_t *pcm, snd_pcm_hw_params_t *params, unsigned int *val, int *dir)
	Restrict a configuration space to have period time nearest to a target. More...
int	snd_pcm_hw_params_set_period_time_first (snd_pcm_t *pcm, snd_pcm_hw_params_t *params, unsigned int *val, int *dir)
	Restrict a configuration space to contain only its minimum period time. More...
int	snd_pcm_hw_params_set_period_time_last (snd_pcm_t *pcm, snd_pcm_hw_params_t *params, unsigned int *val, int *dir)
	Restrict a configuration space to contain only its maximum period time. More...
int	snd_pcm_hw_params_get_period_size (const snd_pcm_hw_params_t *params, snd_pcm_uframes_t *frames, int *dir)
	Extract period size from a configuration space. More...
int	snd_pcm_hw_params_get_period_size_min (const snd_pcm_hw_params_t *params, snd_pcm_uframes_t *frames, int *dir)
	Extract minimum period size from a configuration space. More...
int	snd_pcm_hw_params_get_period_size_max (const snd_pcm_hw_params_t *params, snd_pcm_uframes_t *frames, int *dir)
	Extract maximum period size from a configuration space. More...
int	snd_pcm_hw_params_test_period_size (snd_pcm_t *pcm, snd_pcm_hw_params_t *params, snd_pcm_uframes_t val, int dir)
	Verify if a period size is available inside a configuration space for a PCM. More...
int	snd_pcm_hw_params_set_period_size (snd_pcm_t *pcm, snd_pcm_hw_params_t *params, snd_pcm_uframes_t val, int dir)
	Restrict a configuration space to contain only one period size. More...
int	snd_pcm_hw_params_set_period_size_min (snd_pcm_t *pcm, snd_pcm_hw_params_t *params, snd_pcm_uframes_t *val, int *dir)
	Restrict a configuration space with a minimum period size. More...
int	snd_pcm_hw_params_set_period_size_max (snd_pcm_t *pcm, snd_pcm_hw_params_t *params, snd_pcm_uframes_t *val, int *dir)
	Restrict a configuration space with a maximum period size. More...
int	snd_pcm_hw_params_set_period_size_minmax (snd_pcm_t *pcm, snd_pcm_hw_params_t *params, snd_pcm_uframes_t *min, int *mindir, snd_pcm_uframes_t *max, int *maxdir)
	Restrict a configuration space to have period sizes in a given range. More...
int	snd_pcm_hw_params_set_period_size_near (snd_pcm_t *pcm, snd_pcm_hw_params_t *params, snd_pcm_uframes_t *val, int *dir)
	Restrict a configuration space to have period size nearest to a target. More...
int	snd_pcm_hw_params_set_period_size_first (snd_pcm_t *pcm, snd_pcm_hw_params_t *params, snd_pcm_uframes_t *val, int *dir)
	Restrict a configuration space to contain only its minimum period size. More...
int	snd_pcm_hw_params_set_period_size_last (snd_pcm_t *pcm, snd_pcm_hw_params_t *params, snd_pcm_uframes_t *val, int *dir)
	Restrict a configuration space to contain only its maximum period size. More...
int	snd_pcm_hw_params_set_period_size_integer (snd_pcm_t *pcm, snd_pcm_hw_params_t *params)
	Restrict a configuration space to contain only integer period sizes. More...
int	snd_pcm_hw_params_get_periods (const snd_pcm_hw_params_t *params, unsigned int *val, int *dir)
	Extract periods from a configuration space. More...
int	snd_pcm_hw_params_get_periods_min (const snd_pcm_hw_params_t *params, unsigned int *val, int *dir)
	Extract minimum periods count from a configuration space. More...
int	snd_pcm_hw_params_get_periods_max (const snd_pcm_hw_params_t *params, unsigned int *val, int *dir)
	Extract maximum periods count from a configuration space. More...
int	snd_pcm_hw_params_test_periods (snd_pcm_t *pcm, snd_pcm_hw_params_t *params, unsigned int val, int dir)
	Verify if a periods count is available inside a configuration space for a PCM. More...
int	snd_pcm_hw_params_set_periods (snd_pcm_t *pcm, snd_pcm_hw_params_t *params, unsigned int val, int dir)
	Restrict a configuration space to contain only one periods count. More...
int	snd_pcm_hw_params_set_periods_min (snd_pcm_t *pcm, snd_pcm_hw_params_t *params, unsigned int *val, int *dir)
	Restrict a configuration space with a minimum periods count. More...
int	snd_pcm_hw_params_set_periods_max (snd_pcm_t *pcm, snd_pcm_hw_params_t *params, unsigned int *val, int *dir)
	Restrict a configuration space with a maximum periods count. More...
int	snd_pcm_hw_params_set_periods_minmax (snd_pcm_t *pcm, snd_pcm_hw_params_t *params, unsigned int *min, int *mindir, unsigned int *max, int *maxdir)
	Restrict a configuration space to have periods counts in a given range. More...
int	snd_pcm_hw_params_set_periods_near (snd_pcm_t *pcm, snd_pcm_hw_params_t *params, unsigned int *val, int *dir)
	Restrict a configuration space to have periods count nearest to a target. More...
int	snd_pcm_hw_params_set_periods_first (snd_pcm_t *pcm, snd_pcm_hw_params_t *params, unsigned int *val, int *dir)
	Restrict a configuration space to contain only its minimum periods count. More...
int	snd_pcm_hw_params_set_periods_last (snd_pcm_t *pcm, snd_pcm_hw_params_t *params, unsigned int *val, int *dir)
	Restrict a configuration space to contain only its maximum periods count. More...
int	snd_pcm_hw_params_set_periods_integer (snd_pcm_t *pcm, snd_pcm_hw_params_t *params)
	Restrict a configuration space to contain only integer periods counts. More...
int	snd_pcm_hw_params_get_buffer_time (const snd_pcm_hw_params_t *params, unsigned int *val, int *dir)
	Extract buffer time from a configuration space. More...
int	snd_pcm_hw_params_get_buffer_time_min (const snd_pcm_hw_params_t *params, unsigned int *val, int *dir)
	Extract minimum buffer time from a configuration space. More...
int	snd_pcm_hw_params_get_buffer_time_max (const snd_pcm_hw_params_t *params, unsigned int *val, int *dir)
	Extract maximum buffer time from a configuration space. More...
int	snd_pcm_hw_params_test_buffer_time (snd_pcm_t *pcm, snd_pcm_hw_params_t *params, unsigned int val, int dir)
	Verify if a buffer time is available inside a configuration space for a PCM. More...
int	snd_pcm_hw_params_set_buffer_time (snd_pcm_t *pcm, snd_pcm_hw_params_t *params, unsigned int val, int dir)
	Restrict a configuration space to contain only one buffer time. More...
int	snd_pcm_hw_params_set_buffer_time_min (snd_pcm_t *pcm, snd_pcm_hw_params_t *params, unsigned int *val, int *dir)
	Restrict a configuration space with a minimum buffer time. More...
int	snd_pcm_hw_params_set_buffer_time_max (snd_pcm_t *pcm, snd_pcm_hw_params_t *params, unsigned int *val, int *dir)
	Restrict a configuration space with a maximum buffer time. More...
int	snd_pcm_hw_params_set_buffer_time_minmax (snd_pcm_t *pcm, snd_pcm_hw_params_t *params, unsigned int *min, int *mindir, unsigned int *max, int *maxdir)
	Restrict a configuration space to have buffer times in a given range. More...
int	snd_pcm_hw_params_set_buffer_time_near (snd_pcm_t *pcm, snd_pcm_hw_params_t *params, unsigned int *val, int *dir)
	Restrict a configuration space to have buffer time nearest to a target. More...
int	snd_pcm_hw_params_set_buffer_time_first (snd_pcm_t *pcm, snd_pcm_hw_params_t *params, unsigned int *val, int *dir)
	Restrict a configuration space to contain only its minimum buffer time. More...
int	snd_pcm_hw_params_set_buffer_time_last (snd_pcm_t *pcm, snd_pcm_hw_params_t *params, unsigned int *val, int *dir)
	Restrict a configuration space to contain only its maximum buffered time. More...
int	snd_pcm_hw_params_get_buffer_size (const snd_pcm_hw_params_t *params, snd_pcm_uframes_t *val)
	Extract buffer size from a configuration space. More...
int	snd_pcm_hw_params_get_buffer_size_min (const snd_pcm_hw_params_t *params, snd_pcm_uframes_t *val)
	Extract minimum buffer size from a configuration space. More...
int	snd_pcm_hw_params_get_buffer_size_max (const snd_pcm_hw_params_t *params, snd_pcm_uframes_t *val)
	Extract maximum buffer size from a configuration space. More...
int	snd_pcm_hw_params_test_buffer_size (snd_pcm_t *pcm, snd_pcm_hw_params_t *params, snd_pcm_uframes_t val)
	Verify if a buffer size is available inside a configuration space for a PCM. More...
int	snd_pcm_hw_params_set_buffer_size (snd_pcm_t *pcm, snd_pcm_hw_params_t *params, snd_pcm_uframes_t val)
	Restrict a configuration space to contain only one buffer size. More...
int	snd_pcm_hw_params_set_buffer_size_min (snd_pcm_t *pcm, snd_pcm_hw_params_t *params, snd_pcm_uframes_t *val)
	Restrict a configuration space with a minimum buffer size. More...
int	snd_pcm_hw_params_set_buffer_size_max (snd_pcm_t *pcm, snd_pcm_hw_params_t *params, snd_pcm_uframes_t *val)
	Restrict a configuration space with a maximum buffer size. More...
int	snd_pcm_hw_params_set_buffer_size_minmax (snd_pcm_t *pcm, snd_pcm_hw_params_t *params, snd_pcm_uframes_t *min, snd_pcm_uframes_t *max)
	Restrict a configuration space to have buffer sizes in a given range. More...
int	snd_pcm_hw_params_set_buffer_size_near (snd_pcm_t *pcm, snd_pcm_hw_params_t *params, snd_pcm_uframes_t *val)
	Restrict a configuration space to have buffer size nearest to a target. More...
int	snd_pcm_hw_params_set_buffer_size_first (snd_pcm_t *pcm, snd_pcm_hw_params_t *params, snd_pcm_uframes_t *val)
	Restrict a configuration space to contain only its minimum buffer size. More...
int	snd_pcm_hw_params_set_buffer_size_last (snd_pcm_t *pcm, snd_pcm_hw_params_t *params, snd_pcm_uframes_t *val)
	Restrict a configuration space to contain only its maximum buffer size. More...
int	snd_pcm_hw_params_get_min_align (const snd_pcm_hw_params_t *params, snd_pcm_uframes_t *val)
	Get the minimum transfer align value in samples. More...

Detailed Description

See the PCM (digital audio) interface page for more details.

Macro Definition Documentation

snd_pcm_hw_params_alloca

#define snd_pcm_hw_params_alloca

(

ptr

)

allocate an invalid snd_pcm_hw_params_t using standard alloca

Parameters

ptr	returned pointer

Examples

/test/latency.c, and /test/pcm.c.

Function Documentation

snd_pcm_hw_params_any()

int snd_pcm_hw_params_any	(	snd_pcm_t *	pcm,
		snd_pcm_hw_params_t *	params
	)

Fill params with a full configuration space for a PCM.

Parameters

pcm	PCM handle
params	Configuration space

The configuration space will be filled with all possible ranges for the PCM device.

Examples

/test/latency.c, and /test/pcm.c.

snd_pcm_hw_params_can_disable_period_wakeup()

int snd_pcm_hw_params_can_disable_period_wakeup

(

const snd_pcm_hw_params_t *

params

)

Check if hardware can disable period wakeups.

Parameters

params

Configuration space

Return values

0	Hardware cannot disable period wakeups
1	Hardware can disable period wakeups

snd_pcm_hw_params_can_mmap_sample_resolution()

int snd_pcm_hw_params_can_mmap_sample_resolution

(

const snd_pcm_hw_params_t *

params

)

Check if hardware supports sample-resolution mmap for given configuration.

Parameters

params

Configuration space

Return values

0	Hardware doesn't support sample-resolution mmap
1	Hardware supports sample-resolution mmap

This function should only be called when the configuration space contains a single configuration. Call snd_pcm_hw_params to choose a single configuration from the configuration space.

snd_pcm_hw_params_can_overrange()

int snd_pcm_hw_params_can_overrange

(

const snd_pcm_hw_params_t *

params

)

Check if hardware supports overrange detection.

Parameters

params

Configuration space

Return values

0	Hardware doesn't support overrange detection
1	Hardware supports overrange detection

This function should only be called when the configuration space contains a single configuration. Call snd_pcm_hw_params to choose a single configuration from the configuration space.

snd_pcm_hw_params_can_pause()

int snd_pcm_hw_params_can_pause

(

const snd_pcm_hw_params_t *

params

)

Check if hardware supports pause.

Parameters

params

Configuration space

Return values

0	Hardware doesn't support pause
1	Hardware supports pause

This function should only be called when the configuration space contains a single configuration. Call snd_pcm_hw_params to choose a single configuration from the configuration space.

snd_pcm_hw_params_can_resume()

int snd_pcm_hw_params_can_resume

(

const snd_pcm_hw_params_t *

params

)

Check if hardware supports resume.

Parameters

params

Configuration space

Return values

0	Hardware doesn't support resume
1	Hardware supports resume

This function should only be called when the configuration space contains a single configuration. Call snd_pcm_hw_params to choose a single configuration from the configuration space.

snd_pcm_hw_params_can_sync_start()

int snd_pcm_hw_params_can_sync_start

(

const snd_pcm_hw_params_t *

params

)

Check if hardware supports synchronized start with sample resolution.

Parameters

params

Configuration space

Return values

0	Hardware doesn't support synchronized start
1	Hardware supports synchronized start

This function should only be called when the configuration space contains a single configuration. Call snd_pcm_hw_params to choose a single configuration from the configuration space.

snd_pcm_hw_params_copy()

void snd_pcm_hw_params_copy	(	snd_pcm_hw_params_t *	dst,
		const snd_pcm_hw_params_t *	src
	)

copy one snd_pcm_hw_params_t to another

Parameters

dst	pointer to destination
src	pointer to source

Examples

/test/latency.c.

snd_pcm_hw_params_free()

void snd_pcm_hw_params_free

(

snd_pcm_hw_params_t *

obj

)

frees a previously allocated snd_pcm_hw_params_t

Parameters

obj	pointer to object to free

snd_pcm_hw_params_get_access()

int snd_pcm_hw_params_get_access	(	const snd_pcm_hw_params_t *	params,
		snd_pcm_access_t *	access
	)

Extract access type from a configuration space.

Parameters

params	Configuration space
access	Returned value

Returns

access type otherwise a negative error code if the configuration space does not contain a single value

snd_pcm_hw_params_get_access_mask()

int snd_pcm_hw_params_get_access_mask	(	snd_pcm_hw_params_t *	params,
		snd_pcm_access_mask_t *	mask
	)

Get access mask from a configuration space.

Parameters

params	Configuration space
mask	Returned Access mask

snd_pcm_hw_params_get_buffer_size()

int snd_pcm_hw_params_get_buffer_size	(	const snd_pcm_hw_params_t *	params,
		snd_pcm_uframes_t *	val
	)

Extract buffer size from a configuration space.

Parameters

params	Configuration space
val	Returned buffer size in frames

Returns

0 otherwise a negative error code if the configuration space does not contain a single value

Examples

/test/latency.c, and /test/pcm.c.

snd_pcm_hw_params_get_buffer_size_max()

int snd_pcm_hw_params_get_buffer_size_max	(	const snd_pcm_hw_params_t *	params,
		snd_pcm_uframes_t *	val
	)

Extract maximum buffer size from a configuration space.

Parameters

params	Configuration space
val	Returned approximate maximum buffer size in frames

Returns

0 otherwise a negative error code

Exact value is <,=,> the returned one following dir (-1,0,1)

snd_pcm_hw_params_get_buffer_size_min()

int snd_pcm_hw_params_get_buffer_size_min	(	const snd_pcm_hw_params_t *	params,
		snd_pcm_uframes_t *	val
	)

Extract minimum buffer size from a configuration space.

Parameters

params	Configuration space
val	Returned approximate minimum buffer size in frames

Returns

0 otherwise a negative error code

snd_pcm_hw_params_get_buffer_time()

int snd_pcm_hw_params_get_buffer_time	(	const snd_pcm_hw_params_t *	params,
		unsigned int *	val,
		int *	dir
	)

Extract buffer time from a configuration space.

Parameters

params	Configuration space
val	Returned buffer time in us
dir	Sub unit direction

Returns

0 otherwise a negative error code if the configuration space does not contain a single value

Actual exact value is <,=,> the approximate one following dir (-1, 0, 1)

snd_pcm_hw_params_get_buffer_time_max()

int snd_pcm_hw_params_get_buffer_time_max	(	const snd_pcm_hw_params_t *	params,
		unsigned int *	val,
		int *	dir
	)

Extract maximum buffer time from a configuration space.

Parameters

params	Configuration space
val	approximate maximum buffer duration in us
dir	Sub unit direction

Returns

0 otherwise a negative error code

Exact value is <,=,> the returned one following dir (-1,0,1)

snd_pcm_hw_params_get_buffer_time_min()

int snd_pcm_hw_params_get_buffer_time_min	(	const snd_pcm_hw_params_t *	params,
		unsigned int *	val,
		int *	dir
	)

Extract minimum buffer time from a configuration space.

Parameters

params	Configuration space
val	approximate minimum buffer duration in us
dir	Sub unit direction

Returns

0 otherwise a negative error code

Exact value is <,=,> the returned one following dir (-1,0,1)

snd_pcm_hw_params_get_channels()

int snd_pcm_hw_params_get_channels	(	const snd_pcm_hw_params_t *	params,
		unsigned int *	val
	)

Extract channels from a configuration space.

Parameters

params	Configuration space
val	Returned channels count

Returns

0 otherwise a negative error code if the configuration space does not contain a single value

snd_pcm_hw_params_get_channels_max()

int snd_pcm_hw_params_get_channels_max	(	const snd_pcm_hw_params_t *	params,
		unsigned int *	val
	)

Extract maximum channels count from a configuration space.

Parameters

params	Configuration space
val	maximum channels count

Returns

0 otherwise a negative error code

snd_pcm_hw_params_get_channels_min()

int snd_pcm_hw_params_get_channels_min	(	const snd_pcm_hw_params_t *	params,
		unsigned int *	val
	)

Extract minimum channels count from a configuration space.

Parameters

params	Configuration space
val	minimum channels count

Returns

0 otherwise a negative error code

snd_pcm_hw_params_get_export_buffer()

int snd_pcm_hw_params_get_export_buffer	(	snd_pcm_t *	pcm,
		snd_pcm_hw_params_t *	params,
		unsigned int *	val
	)

Extract buffer accessibility from a configuration space.

Parameters

pcm	PCM handle
params	Configuration space
val	0 = disable, 1 = enable exporting buffer

Returns

0 otherwise a negative error code

snd_pcm_hw_params_get_fifo_size()

int snd_pcm_hw_params_get_fifo_size

(

const snd_pcm_hw_params_t *

params

)

Get hardware FIFO size info from a configuration space.

Parameters

params

Configuration space

Returns

FIFO size in frames otherwise a negative error code if the info is not available

This function should only be called when the configuration space contains a single configuration. Call snd_pcm_hw_params to choose a single configuration from the configuration space.

snd_pcm_hw_params_get_format()

int snd_pcm_hw_params_get_format	(	const snd_pcm_hw_params_t *	params,
		snd_pcm_format_t *	format
	)

Extract format from a configuration space.

Parameters

params	Configuration space
format	returned format

Returns

format otherwise a negative error code if the configuration space does not contain a single value

snd_pcm_hw_params_get_format_mask()

void snd_pcm_hw_params_get_format_mask	(	snd_pcm_hw_params_t *	params,
		snd_pcm_format_mask_t *	mask
	)

Get format mask from a configuration space.

Parameters

params	Configuration space
mask	Returned Format mask

snd_pcm_hw_params_get_min_align()

int snd_pcm_hw_params_get_min_align	(	const snd_pcm_hw_params_t *	params,
		snd_pcm_uframes_t *	val
	)

Get the minimum transfer align value in samples.

Parameters

params	Configuration space
val	Returned minimum align value

Returns

0 otherwise a negative error code if the configuration space does not contain a single value

snd_pcm_hw_params_get_period_size()

int snd_pcm_hw_params_get_period_size	(	const snd_pcm_hw_params_t *	params,
		snd_pcm_uframes_t *	val,
		int *	dir
	)

Extract period size from a configuration space.

Parameters

params	Configuration space
val	Returned approximate period size in frames
dir	Sub unit direction

Returns

0 otherwise a negative error code if the configuration space does not contain a single value

Actual exact value is <,=,> the approximate one following dir (-1, 0, 1)

Examples

/test/latency.c, and /test/pcm.c.

snd_pcm_hw_params_get_period_size_max()

int snd_pcm_hw_params_get_period_size_max	(	const snd_pcm_hw_params_t *	params,
		snd_pcm_uframes_t *	val,
		int *	dir
	)

Extract maximum period size from a configuration space.

Parameters

params	Configuration space
val	approximate minimum period size in frames
dir	Sub unit direction

Returns

0 otherwise a negative error code

Exact value is <,=,> the returned one following dir (-1,0,1)

snd_pcm_hw_params_get_period_size_min()

int snd_pcm_hw_params_get_period_size_min	(	const snd_pcm_hw_params_t *	params,
		snd_pcm_uframes_t *	val,
		int *	dir
	)

Extract minimum period size from a configuration space.

Parameters

params	Configuration space
val	approximate minimum period size in frames
dir	Sub unit direction

Returns

0 otherwise a negative error code

Exact value is <,=,> the returned one following dir (-1,0,1)

snd_pcm_hw_params_get_period_time()

int snd_pcm_hw_params_get_period_time	(	const snd_pcm_hw_params_t *	params,
		unsigned int *	val,
		int *	dir
	)

Extract period time from a configuration space.

Parameters

params	Configuration space
val	Returned approximate period duration in us
dir	Sub unit direction

Returns

0 otherwise a negative error code if the configuration space does not contain a single value

Actual exact value is <,=,> the approximate one following dir (-1, 0, 1)

Examples

/test/latency.c.

snd_pcm_hw_params_get_period_time_max()

int snd_pcm_hw_params_get_period_time_max	(	const snd_pcm_hw_params_t *	params,
		unsigned int *	val,
		int *	dir
	)

Extract maximum period time from a configuration space.

Parameters

params	Configuration space
val	approximate maximum period duration in us
dir	Sub unit direction

Returns

0 otherwise a negative error code

Exact value is <,=,> the returned one following dir (-1,0,1)

snd_pcm_hw_params_get_period_time_min()

int snd_pcm_hw_params_get_period_time_min	(	const snd_pcm_hw_params_t *	params,
		unsigned int *	val,
		int *	dir
	)

Extract minimum period time from a configuration space.

Parameters

params	Configuration space
val	approximate minimum period duration in us
dir	Sub unit direction

Returns

0 otherwise a negative error code

Exact value is <,=,> the returned one following dir (-1,0,1)

snd_pcm_hw_params_get_period_wakeup()

int snd_pcm_hw_params_get_period_wakeup	(	snd_pcm_t *	pcm,
		snd_pcm_hw_params_t *	params,
		unsigned int *	val
	)

Extract period wakeup flag from a configuration space.

Parameters

pcm	PCM handle
params	Configuration space
val	0 = disabled, 1 = enabled period wakeups

Returns

Zero on success, otherwise a negative error code.

snd_pcm_hw_params_get_periods()

int snd_pcm_hw_params_get_periods	(	const snd_pcm_hw_params_t *	params,
		unsigned int *	val,
		int *	dir
	)

Extract periods from a configuration space.

Parameters

params	Configuration space
val	approximate periods per buffer
dir	Sub unit direction

Returns

0 otherwise a negative error code if the configuration space does not contain a single value

Actual exact value is <,=,> the approximate one following dir (-1, 0, 1)

snd_pcm_hw_params_get_periods_max()

int snd_pcm_hw_params_get_periods_max	(	const snd_pcm_hw_params_t *	params,
		unsigned int *	val,
		int *	dir
	)

Extract maximum periods count from a configuration space.

Parameters

params	Configuration space
val	approximate maximum periods per buffer
dir	Sub unit direction

Returns

0 otherwise a negative error code

Exact value is <,=,> the returned one following dir (-1,0,1)

snd_pcm_hw_params_get_periods_min()

int snd_pcm_hw_params_get_periods_min	(	const snd_pcm_hw_params_t *	params,
		unsigned int *	val,
		int *	dir
	)

Extract minimum periods count from a configuration space.

Parameters

params	Configuration space
val	approximate minimum periods per buffer
dir	Sub unit direction

Returns

0 otherwise a negative error code

Exact value is <,=,> the returned one following dir (-1,0,1)

Examples

/test/latency.c.

snd_pcm_hw_params_get_rate()

int snd_pcm_hw_params_get_rate	(	const snd_pcm_hw_params_t *	params,
		unsigned int *	val,
		int *	dir
	)

Extract rate from a configuration space.

Parameters

params	Configuration space
val	Returned approximate rate
dir	Sub unit direction

Returns

0 otherwise a negative error code if the configuration space does not contain a single value

Actual exact value is <,=,> the approximate one following dir (-1, 0, 1)

snd_pcm_hw_params_get_rate_max()

int snd_pcm_hw_params_get_rate_max	(	const snd_pcm_hw_params_t *	params,
		unsigned int *	val,
		int *	dir
	)

Extract maximum rate from a configuration space.

Parameters

params	Configuration space
val	Returned approximate maximum rate
dir	Sub unit direction

Returns

0 otherwise a negative error code

Exact value is <,=,> the returned one following dir (-1,0,1)

snd_pcm_hw_params_get_rate_min()

int snd_pcm_hw_params_get_rate_min	(	const snd_pcm_hw_params_t *	params,
		unsigned int *	val,
		int *	dir
	)

Extract minimum rate from a configuration space.

Parameters

params	Configuration space
val	Returned approximate minimum rate
dir	Sub unit direction

Returns

0 otherwise a negative error code

Exact value is <,=,> the returned one following dir (-1,0,1)

snd_pcm_hw_params_get_rate_numden()

int snd_pcm_hw_params_get_rate_numden	(	const snd_pcm_hw_params_t *	params,
		unsigned int *	rate_num,
		unsigned int *	rate_den
	)

Get rate exact info from a configuration space.

Parameters

params	Configuration space
rate_num	Pointer to returned rate numerator
rate_den	Pointer to returned rate denominator

Returns

0 otherwise a negative error code if the info is not available

This function should only be called when the configuration space contains a single configuration. Call snd_pcm_hw_params to choose a single configuration from the configuration space.

snd_pcm_hw_params_get_rate_resample()

int snd_pcm_hw_params_get_rate_resample	(	snd_pcm_t *	pcm,
		snd_pcm_hw_params_t *	params,
		unsigned int *	val
	)

Extract resample state from a configuration space.

Parameters

pcm	PCM handle
params	Configuration space
val	0 = disable, 1 = enable rate resampling

Returns

0 otherwise a negative error code

snd_pcm_hw_params_get_sbits()

int snd_pcm_hw_params_get_sbits

(

const snd_pcm_hw_params_t *

params

)

Get sample resolution info from a configuration space.

Parameters

params

Configuration space

Returns

signification bits in sample otherwise a negative error code if the info is not available

This function should only be called when the configuration space contains a single configuration. Call snd_pcm_hw_params to choose a single configuration from the configuration space.

snd_pcm_hw_params_get_subformat()

int snd_pcm_hw_params_get_subformat	(	const snd_pcm_hw_params_t *	params,
		snd_pcm_subformat_t *	subformat
	)

Extract subformat from a configuration space.

Parameters

params	Configuration space
subformat	Returned subformat value

Returns

subformat otherwise a negative error code if the configuration space does not contain a single value

snd_pcm_hw_params_get_subformat_mask()

void snd_pcm_hw_params_get_subformat_mask	(	snd_pcm_hw_params_t *	params,
		snd_pcm_subformat_mask_t *	mask
	)

Get subformat mask from a configuration space.

Parameters

params	Configuration space
mask	Returned Subformat mask

snd_pcm_hw_params_is_batch()

int snd_pcm_hw_params_is_batch

(

const snd_pcm_hw_params_t *

params

)

Check if hardware does double buffering for data transfers for given configuration.

Parameters

params

Configuration space

Return values

0	Hardware doesn't do double buffering for data transfers
1	Hardware does double buffering for data transfers

This function should only be called when the configuration space contains a single configuration. Call snd_pcm_hw_params to choose a single configuration from the configuration space.

snd_pcm_hw_params_is_block_transfer()

int snd_pcm_hw_params_is_block_transfer

(

const snd_pcm_hw_params_t *

params

)

Check if hardware does block transfers for samples for given configuration.

Parameters

params

Configuration space

Return values

0	Hardware doesn't block transfers
1	Hardware does block transfers

This function should only be called when the configuration space contains a single configuration. Call snd_pcm_hw_params to choose a single configuration from the configuration space.

snd_pcm_hw_params_is_double()

int snd_pcm_hw_params_is_double

(

const snd_pcm_hw_params_t *

params

)

Check if hardware does double buffering for start/stop for given configuration.

Parameters

params

Configuration space

Return values

0	Hardware doesn't do double buffering for start/stop
1	Hardware does double buffering for start/stop

This function should only be called when the configuration space contains a single configuration. Call snd_pcm_hw_params to choose a single configuration from the configuration space.

snd_pcm_hw_params_is_half_duplex()

int snd_pcm_hw_params_is_half_duplex

(

const snd_pcm_hw_params_t *

params

)

Check if hardware does half-duplex only.

Parameters

params

Configuration space

Return values

0	Hardware doesn't do half-duplex
1	Hardware does half-duplex

This function should only be called when the configuration space contains a single configuration. Call snd_pcm_hw_params to choose a single configuration from the configuration space.

snd_pcm_hw_params_is_joint_duplex()

int snd_pcm_hw_params_is_joint_duplex

(

const snd_pcm_hw_params_t *

params

)

Check if hardware does joint-duplex (playback and capture are somewhat correlated)

Parameters

params

Configuration space

Return values

0	Hardware doesn't do joint-duplex
1	Hardware does joint-duplex

This function should only be called when the configuration space contains a single configuration. Call snd_pcm_hw_params to choose a single configuration from the configuration space.

snd_pcm_hw_params_is_monotonic()

int snd_pcm_hw_params_is_monotonic

(

const snd_pcm_hw_params_t *

params

)

Check if timestamps are monotonic for given configuration.

Parameters

params

Configuration space

Return values

0	Device doesn't do monotomic timestamps
1	Device does monotonic timestamps

This function should only be called when the configuration space contains a single configuration. Call snd_pcm_hw_params to choose a single configuration from the configuration space.

snd_pcm_hw_params_malloc()

int snd_pcm_hw_params_malloc

(

snd_pcm_hw_params_t **

ptr

)

allocate an invalid snd_pcm_hw_params_t using standard malloc

Parameters

ptr	returned pointer

Returns

0 on success otherwise negative error code

snd_pcm_hw_params_set_access()

int snd_pcm_hw_params_set_access	(	snd_pcm_t *	pcm,
		snd_pcm_hw_params_t *	params,
		snd_pcm_access_t	access
	)

Restrict a configuration space to contain only one access type.

Parameters

pcm	PCM handle
params	Configuration space
access	access type

Returns

0 otherwise a negative error code if configuration space would become empty

Examples

/test/latency.c, and /test/pcm.c.

snd_pcm_hw_params_set_access_first()

int snd_pcm_hw_params_set_access_first	(	snd_pcm_t *	pcm,
		snd_pcm_hw_params_t *	params,
		snd_pcm_access_t *	access
	)

Restrict a configuration space to contain only its first access type.

Parameters

pcm	PCM handle
params	Configuration space
access	Returned first access type

Returns

0 otherwise a negative error code

snd_pcm_hw_params_set_access_last()

int snd_pcm_hw_params_set_access_last	(	snd_pcm_t *	pcm,
		snd_pcm_hw_params_t *	params,
		snd_pcm_access_t *	access
	)

Restrict a configuration space to contain only its last access type.

Parameters

pcm	PCM handle
params	Configuration space
access	Returned last access type

Returns

0 otherwise a negative error code

snd_pcm_hw_params_set_access_mask()

int snd_pcm_hw_params_set_access_mask	(	snd_pcm_t *	pcm,
		snd_pcm_hw_params_t *	params,
		snd_pcm_access_mask_t *	mask
	)

Restrict a configuration space to contain only a set of access types.

Parameters

pcm	PCM handle
params	Configuration space
mask	Access mask

Returns

0 otherwise a negative error code

snd_pcm_hw_params_set_buffer_size()

int snd_pcm_hw_params_set_buffer_size	(	snd_pcm_t *	pcm,
		snd_pcm_hw_params_t *	params,
		snd_pcm_uframes_t	val
	)

Restrict a configuration space to contain only one buffer size.

Parameters

pcm	PCM handle
params	Configuration space
val	buffer size in frames

Returns

0 otherwise a negative error code if configuration space would become empty

Wanted exact value is <,=,> val following dir (-1,0,1)

snd_pcm_hw_params_set_buffer_size_first()

int snd_pcm_hw_params_set_buffer_size_first	(	snd_pcm_t *	pcm,
		snd_pcm_hw_params_t *	params,
		snd_pcm_uframes_t *	val
	)

Restrict a configuration space to contain only its minimum buffer size.

Parameters

pcm	PCM handle
params	Configuration space
val	Returned minimum buffer size in frames

Returns

buffer size in frames

snd_pcm_hw_params_set_buffer_size_last()

int snd_pcm_hw_params_set_buffer_size_last	(	snd_pcm_t *	pcm,
		snd_pcm_hw_params_t *	params,
		snd_pcm_uframes_t *	val
	)

Restrict a configuration space to contain only its maximum buffer size.

Parameters

pcm	PCM handle
params	Configuration space
val	Returned maximum buffer size in frames

Returns

0 otherwise a negative error code

snd_pcm_hw_params_set_buffer_size_max()

int snd_pcm_hw_params_set_buffer_size_max	(	snd_pcm_t *	pcm,
		snd_pcm_hw_params_t *	params,
		snd_pcm_uframes_t *	val
	)

Restrict a configuration space with a maximum buffer size.

Parameters

pcm	PCM handle
params	Configuration space
val	approximate maximum buffer size in frames (on return filled with actual maximum)

Returns

0 otherwise a negative error code if configuration space would become empty

snd_pcm_hw_params_set_buffer_size_min()

int snd_pcm_hw_params_set_buffer_size_min	(	snd_pcm_t *	pcm,
		snd_pcm_hw_params_t *	params,
		snd_pcm_uframes_t *	val
	)

Restrict a configuration space with a minimum buffer size.

Parameters

pcm	PCM handle
params	Configuration space
val	approximate minimum buffer size in frames (on return filled with actual minimum)

Returns

0 otherwise a negative error code if configuration space would become empty

snd_pcm_hw_params_set_buffer_size_minmax()

int snd_pcm_hw_params_set_buffer_size_minmax	(	snd_pcm_t *	pcm,
		snd_pcm_hw_params_t *	params,
		snd_pcm_uframes_t *	min,
		snd_pcm_uframes_t *	max
	)

Restrict a configuration space to have buffer sizes in a given range.

Parameters

pcm	PCM handle
params	Configuration space
min	approximate minimum buffer size in frames (on return filled with actual minimum)
max	approximate maximum buffer size in frames (on return filled with actual maximum)

Returns

0 otherwise a negative error code if configuration space would become empty

snd_pcm_hw_params_set_buffer_size_near()

int snd_pcm_hw_params_set_buffer_size_near	(	snd_pcm_t *	pcm,
		snd_pcm_hw_params_t *	params,
		snd_pcm_uframes_t *	val
	)

Restrict a configuration space to have buffer size nearest to a target.

Parameters

pcm	PCM handle
params	Configuration space
val	approximate target buffer size in frames / returned chosen approximate target buffer size in frames

Returns

0 otherwise a negative error code if configuration space is empty

Examples

/test/latency.c.

snd_pcm_hw_params_set_buffer_time()

int snd_pcm_hw_params_set_buffer_time	(	snd_pcm_t *	pcm,
		snd_pcm_hw_params_t *	params,
		unsigned int	val,
		int	dir
	)

Restrict a configuration space to contain only one buffer time.

Parameters

pcm	PCM handle
params	Configuration space
val	approximate buffer duration in us
dir	Sub unit direction

Returns

0 otherwise a negative error code if configuration space would become empty

Wanted exact value is <,=,> val following dir (-1,0,1)

snd_pcm_hw_params_set_buffer_time_first()

int snd_pcm_hw_params_set_buffer_time_first	(	snd_pcm_t *	pcm,
		snd_pcm_hw_params_t *	params,
		unsigned int *	val,
		int *	dir
	)

Restrict a configuration space to contain only its minimum buffer time.

Parameters

pcm	PCM handle
params	Configuration space
val	Returned approximate minimum buffer duration in us
dir	Sub unit direction

Returns

0 otherwise a negative error code

Actual exact value is <,=,> the approximate one following dir (-1, 0, 1)

snd_pcm_hw_params_set_buffer_time_last()

int snd_pcm_hw_params_set_buffer_time_last	(	snd_pcm_t *	pcm,
		snd_pcm_hw_params_t *	params,
		unsigned int *	val,
		int *	dir
	)

Restrict a configuration space to contain only its maximum buffered time.

Parameters

pcm	PCM handle
params	Configuration space
val	Returned approximate maximum buffer duration in us
dir	Sub unit direction

Returns

0 otherwise a negative error code

Actual exact value is <,=,> the approximate one following dir (-1, 0, 1)

snd_pcm_hw_params_set_buffer_time_max()

int snd_pcm_hw_params_set_buffer_time_max	(	snd_pcm_t *	pcm,
		snd_pcm_hw_params_t *	params,
		unsigned int *	val,
		int *	dir
	)

Restrict a configuration space with a maximum buffer time.

Parameters

pcm	PCM handle
params	Configuration space
val	approximate maximum buffer duration in us (on return filled with actual maximum)
dir	Sub unit direction (on return filled with actual direction)

Returns

0 otherwise a negative error code if configuration space would become empty

Wanted/actual exact maximum is <,=,> val following dir (-1,0,1)

snd_pcm_hw_params_set_buffer_time_min()

int snd_pcm_hw_params_set_buffer_time_min	(	snd_pcm_t *	pcm,
		snd_pcm_hw_params_t *	params,
		unsigned int *	val,
		int *	dir
	)

Restrict a configuration space with a minimum buffer time.

Parameters

pcm	PCM handle
params	Configuration space
val	approximate minimum buffer duration in us (on return filled with actual minimum)
dir	Sub unit direction (on return filled with actual direction)

Returns

0 otherwise a negative error code if configuration space would become empty

Wanted/actual exact minimum is <,=,> val following dir (-1,0,1)

snd_pcm_hw_params_set_buffer_time_minmax()

int snd_pcm_hw_params_set_buffer_time_minmax	(	snd_pcm_t *	pcm,
		snd_pcm_hw_params_t *	params,
		unsigned int *	min,
		int *	mindir,
		unsigned int *	max,
		int *	maxdir
	)

Restrict a configuration space to have buffer times in a given range.

Parameters

pcm	PCM handle
params	Configuration space
min	approximate minimum buffer duration in us (on return filled with actual minimum)
mindir	Sub unit direction for minimum (on return filled with actual direction)
max	approximate maximum buffer duration in us (on return filled with actual maximum)
maxdir	Sub unit direction for maximum (on return filled with actual direction)

Returns

0 otherwise a negative error code if configuration space would become empty

Wanted/actual exact min/max is <,=,> val following dir (-1,0,1)

snd_pcm_hw_params_set_buffer_time_near()

int snd_pcm_hw_params_set_buffer_time_near	(	snd_pcm_t *	pcm,
		snd_pcm_hw_params_t *	params,
		unsigned int *	val,
		int *	dir
	)

Restrict a configuration space to have buffer time nearest to a target.

Parameters

pcm	PCM handle
params	Configuration space
val	approximate target buffer duration in us / returned chosen approximate target buffer duration
dir	Sub unit direction

Returns

0 otherwise a negative error code if configuration space is empty

target/chosen exact value is <,=,> val following dir (-1,0,1)

Examples

/test/pcm.c.

snd_pcm_hw_params_set_channels()

int snd_pcm_hw_params_set_channels	(	snd_pcm_t *	pcm,
		snd_pcm_hw_params_t *	params,
		unsigned int	val
	)

Restrict a configuration space to contain only one channels count.

Parameters

pcm	PCM handle
params	Configuration space
val	channels count

Returns

0 otherwise a negative error code if configuration space would become empty

Examples

/test/latency.c, and /test/pcm.c.

snd_pcm_hw_params_set_channels_first()

int snd_pcm_hw_params_set_channels_first	(	snd_pcm_t *	pcm,
		snd_pcm_hw_params_t *	params,
		unsigned int *	val
	)

Restrict a configuration space to contain only its minimum channels count.

Parameters

pcm	PCM handle
params	Configuration space
val	minimum channels count

Returns

0 otherwise a negative error code

snd_pcm_hw_params_set_channels_last()

int snd_pcm_hw_params_set_channels_last	(	snd_pcm_t *	pcm,
		snd_pcm_hw_params_t *	params,
		unsigned int *	val
	)

Restrict a configuration space to contain only its maximum channels count.

Parameters

pcm	PCM handle
params	Configuration space
val	maximum channels count

Returns

0 otherwise a negative error code

snd_pcm_hw_params_set_channels_max()

int snd_pcm_hw_params_set_channels_max	(	snd_pcm_t *	pcm,
		snd_pcm_hw_params_t *	params,
		unsigned int *	val
	)

Restrict a configuration space with a maximum channels count.

Parameters

pcm	PCM handle
params	Configuration space
val	maximum channels count (on return filled with actual maximum)

Returns

0 otherwise a negative error code if configuration space would become empty

snd_pcm_hw_params_set_channels_min()

int snd_pcm_hw_params_set_channels_min	(	snd_pcm_t *	pcm,
		snd_pcm_hw_params_t *	params,
		unsigned int *	val
	)

Restrict a configuration space with a minimum channels count.

Parameters

pcm	PCM handle
params	Configuration space
val	minimum channels count (on return filled with actual minimum)

Returns

0 otherwise a negative error code if configuration space would become empty

snd_pcm_hw_params_set_channels_minmax()

int snd_pcm_hw_params_set_channels_minmax	(	snd_pcm_t *	pcm,
		snd_pcm_hw_params_t *	params,
		unsigned int *	min,
		unsigned int *	max
	)

Restrict a configuration space to have channels counts in a given range.

Parameters

pcm	PCM handle
params	Configuration space
min	minimum channels count (on return filled with actual minimum)
max	maximum channels count (on return filled with actual maximum)

Returns

0 otherwise a negative error code if configuration space would become empty

snd_pcm_hw_params_set_channels_near()

int snd_pcm_hw_params_set_channels_near	(	snd_pcm_t *	pcm,
		snd_pcm_hw_params_t *	params,
		unsigned int *	val
	)

Restrict a configuration space to have channels count nearest to a target.

Parameters

pcm	PCM handle
params	Configuration space
val	target channels count, returned chosen channels count

Returns

0 otherwise a negative error code if configuration space is empty

snd_pcm_hw_params_set_export_buffer()

int snd_pcm_hw_params_set_export_buffer	(	snd_pcm_t *	pcm,
		snd_pcm_hw_params_t *	params,
		unsigned int	val
	)

Restrict a configuration space to allow the buffer to be accessible from outside.

Parameters

pcm	PCM handle
params	Configuration space
val	0 = disable, 1 = enable (default) exporting buffer

Returns

0 otherwise a negative error code

snd_pcm_hw_params_set_format()

int snd_pcm_hw_params_set_format	(	snd_pcm_t *	pcm,
		snd_pcm_hw_params_t *	params,
		snd_pcm_format_t	format
	)

Restrict a configuration space to contain only one format.

Parameters

pcm	PCM handle
params	Configuration space
format	format

Returns

0 otherwise a negative error code

Examples

/test/latency.c, and /test/pcm.c.

snd_pcm_hw_params_set_format_first()

int snd_pcm_hw_params_set_format_first	(	snd_pcm_t *	pcm,
		snd_pcm_hw_params_t *	params,
		snd_pcm_format_t *	format
	)

Restrict a configuration space to contain only its first format.

Parameters

pcm	PCM handle
params	Configuration space
format	Returned first format

Returns

0 otherwise a negative error code

snd_pcm_hw_params_set_format_last()

int snd_pcm_hw_params_set_format_last	(	snd_pcm_t *	pcm,
		snd_pcm_hw_params_t *	params,
		snd_pcm_format_t *	format
	)

Restrict a configuration space to contain only its last format.

Parameters

pcm	PCM handle
params	Configuration space
format	Returned last format

Returns

0 otherwise a negative error code

snd_pcm_hw_params_set_format_mask()

int snd_pcm_hw_params_set_format_mask	(	snd_pcm_t *	pcm,
		snd_pcm_hw_params_t *	params,
		snd_pcm_format_mask_t *	mask
	)

Restrict a configuration space to contain only a set of formats.

Parameters

pcm	PCM handle
params	Configuration space
mask	Format mask

Returns

0 otherwise a negative error code

snd_pcm_hw_params_set_period_size()

int snd_pcm_hw_params_set_period_size	(	snd_pcm_t *	pcm,
		snd_pcm_hw_params_t *	params,
		snd_pcm_uframes_t	val,
		int	dir
	)

Restrict a configuration space to contain only one period size.

Parameters

pcm	PCM handle
params	Configuration space
val	approximate period size in frames
dir	Sub unit direction

Returns

0 otherwise a negative error code if configuration space would become empty

Wanted exact value is <,=,> val following dir (-1,0,1)

snd_pcm_hw_params_set_period_size_first()

int snd_pcm_hw_params_set_period_size_first	(	snd_pcm_t *	pcm,
		snd_pcm_hw_params_t *	params,
		snd_pcm_uframes_t *	val,
		int *	dir
	)

Restrict a configuration space to contain only its minimum period size.

Parameters

pcm	PCM handle
params	Configuration space
val	Returned maximum approximate period size in frames
dir	Sub unit direction

Returns

0 otherwise a negative error code

Actual exact value is <,=,> the approximate one following dir (-1, 0, 1)

snd_pcm_hw_params_set_period_size_integer()

int snd_pcm_hw_params_set_period_size_integer	(	snd_pcm_t *	pcm,
		snd_pcm_hw_params_t *	params
	)

Restrict a configuration space to contain only integer period sizes.

Parameters

pcm	PCM handle
params	Configuration space

Returns

0 otherwise a negative error code if configuration space would become empty

snd_pcm_hw_params_set_period_size_last()

int snd_pcm_hw_params_set_period_size_last	(	snd_pcm_t *	pcm,
		snd_pcm_hw_params_t *	params,
		snd_pcm_uframes_t *	val,
		int *	dir
	)

Restrict a configuration space to contain only its maximum period size.

Parameters

pcm	PCM handle
params	Configuration space
val	Returned maximum approximate period size in frames
dir	Sub unit direction

Returns

0 otherwise a negative error code

Actual exact value is <,=,> the approximate one following dir (-1, 0, 1)

snd_pcm_hw_params_set_period_size_max()

int snd_pcm_hw_params_set_period_size_max	(	snd_pcm_t *	pcm,
		snd_pcm_hw_params_t *	params,
		snd_pcm_uframes_t *	val,
		int *	dir
	)

Restrict a configuration space with a maximum period size.

Parameters

pcm	PCM handle
params	Configuration space
val	approximate maximum period size in frames (on return filled with actual maximum)
dir	Sub unit direction (on return filled with actual direction)

Returns

0 otherwise a negative error code if configuration space would become empty

Wanted/actual exact minimum is <,=,> val following dir (-1,0,1)

snd_pcm_hw_params_set_period_size_min()

int snd_pcm_hw_params_set_period_size_min	(	snd_pcm_t *	pcm,
		snd_pcm_hw_params_t *	params,
		snd_pcm_uframes_t *	val,
		int *	dir
	)

Restrict a configuration space with a minimum period size.

Parameters

pcm	PCM handle
params	Configuration space
val	approximate minimum period size in frames (on return filled with actual minimum)
dir	Sub unit direction (on return filled with actual direction)

Returns

0 otherwise a negative error code if configuration space would become empty

Wanted/actual exact minimum is <,=,> val following dir (-1,0,1)

snd_pcm_hw_params_set_period_size_minmax()

int snd_pcm_hw_params_set_period_size_minmax	(	snd_pcm_t *	pcm,
		snd_pcm_hw_params_t *	params,
		snd_pcm_uframes_t *	min,
		int *	mindir,
		snd_pcm_uframes_t *	max,
		int *	maxdir
	)

Restrict a configuration space to have period sizes in a given range.

Parameters

pcm	PCM handle
params	Configuration space
min	approximate minimum period size in frames (on return filled with actual minimum)
mindir	Sub unit direction for minimum (on return filled with actual direction)
max	approximate maximum period size in frames (on return filled with actual maximum)
maxdir	Sub unit direction for maximum (on return filled with actual direction)

Returns

0 otherwise a negative error code if configuration space would become empty

Wanted/actual exact min/max is <,=,> val following dir (-1,0,1)

snd_pcm_hw_params_set_period_size_near()

int snd_pcm_hw_params_set_period_size_near	(	snd_pcm_t *	pcm,
		snd_pcm_hw_params_t *	params,
		snd_pcm_uframes_t *	val,
		int *	dir
	)

Restrict a configuration space to have period size nearest to a target.

Parameters

pcm	PCM handle
params	Configuration space
val	approximate target period size in frames / returned chosen approximate target period size
dir	Sub unit direction

Returns

0 otherwise a negative error code if configuration space is empty

target/chosen exact value is <,=,> val following dir (-1,0,1)

Examples

/test/latency.c.

snd_pcm_hw_params_set_period_time()

int snd_pcm_hw_params_set_period_time	(	snd_pcm_t *	pcm,
		snd_pcm_hw_params_t *	params,
		unsigned int	val,
		int	dir
	)

Restrict a configuration space to contain only one period time.

Parameters

pcm	PCM handle
params	Configuration space
val	approximate period duration in us
dir	Sub unit direction

Returns

0 otherwise a negative error code if configuration space would become empty

Wanted exact value is <,=,> val following dir (-1,0,1)

snd_pcm_hw_params_set_period_time_first()

int snd_pcm_hw_params_set_period_time_first	(	snd_pcm_t *	pcm,
		snd_pcm_hw_params_t *	params,
		unsigned int *	val,
		int *	dir
	)

Restrict a configuration space to contain only its minimum period time.

Parameters

pcm	PCM handle
params	Configuration space
val	Returned approximate period duration in us
dir	Sub unit direction

Returns

0 otherwise a negative error code

Actual exact value is <,=,> the approximate one following dir (-1, 0, 1)

snd_pcm_hw_params_set_period_time_last()

int snd_pcm_hw_params_set_period_time_last	(	snd_pcm_t *	pcm,
		snd_pcm_hw_params_t *	params,
		unsigned int *	val,
		int *	dir
	)

Restrict a configuration space to contain only its maximum period time.

Parameters

pcm	PCM handle
params	Configuration space
val	Returned maximum approximate period time
dir	Sub unit direction

Returns

approximate period duration in us

snd_pcm_hw_params_set_period_time_max()

int snd_pcm_hw_params_set_period_time_max	(	snd_pcm_t *	pcm,
		snd_pcm_hw_params_t *	params,
		unsigned int *	val,
		int *	dir
	)

Restrict a configuration space with a maximum period time.

Parameters

pcm	PCM handle
params	Configuration space
val	approximate maximum period duration in us (on return filled with actual maximum)
dir	Sub unit direction (on return filled with actual direction)

Returns

0 otherwise a negative error code if configuration space would become empty

Wanted/actual exact maximum is <,=,> val following dir (-1,0,1)

snd_pcm_hw_params_set_period_time_min()

int snd_pcm_hw_params_set_period_time_min	(	snd_pcm_t *	pcm,
		snd_pcm_hw_params_t *	params,
		unsigned int *	val,
		int *	dir
	)

Restrict a configuration space with a minimum period time.

Parameters

pcm	PCM handle
params	Configuration space
val	approximate minimum period duration in us (on return filled with actual minimum)
dir	Sub unit direction (on return filled with actual direction)

Returns

0 otherwise a negative error code if configuration space would become empty

Wanted/actual exact minimum is <,=,> val following dir (-1,0,1)

snd_pcm_hw_params_set_period_time_minmax()

int snd_pcm_hw_params_set_period_time_minmax	(	snd_pcm_t *	pcm,
		snd_pcm_hw_params_t *	params,
		unsigned int *	min,
		int *	mindir,
		unsigned int *	max,
		int *	maxdir
	)

Restrict a configuration space to have period times in a given range.

Parameters

pcm	PCM handle
params	Configuration space
min	approximate minimum period duration in us (on return filled with actual minimum)
mindir	Sub unit direction for minimum (on return filled with actual direction)
max	approximate maximum period duration in us (on return filled with actual maximum)
maxdir	Sub unit direction for maximum (on return filled with actual direction)

Returns

0 otherwise a negative error code if configuration space would become empty

Wanted/actual exact min/max is <,=,> val following dir (-1,0,1)

snd_pcm_hw_params_set_period_time_near()

int snd_pcm_hw_params_set_period_time_near	(	snd_pcm_t *	pcm,
		snd_pcm_hw_params_t *	params,
		unsigned int *	val,
		int *	dir
	)

Restrict a configuration space to have period time nearest to a target.

Parameters

pcm	PCM handle
params	Configuration space
val	approximate target period duration in us / returned chosen approximate target period duration
dir	Sub unit direction

Returns

0 otherwise a negative error code if configuration space is empty

target/chosen exact value is <,=,> val following dir (-1,0,1)

Examples

/test/pcm.c.

snd_pcm_hw_params_set_period_wakeup()

int snd_pcm_hw_params_set_period_wakeup	(	snd_pcm_t *	pcm,
		snd_pcm_hw_params_t *	params,
		unsigned int	val
	)

Restrict a configuration space to settings without period wakeups.

Parameters

pcm	PCM handle
params	Configuration space
val	0 = disable, 1 = enable (default) period wakeup

Returns

Zero on success, otherwise a negative error code.

This function must be called only on devices where non-blocking mode is enabled.

To check whether the hardware does support disabling period wakeups, call snd_pcm_hw_params_can_disable_period_wakeup(). If the hardware does not support this mode, standard period wakeups will be generated.

Even with disabled period wakeups, the period size/time/count parameters are valid; it is suggested to use snd_pcm_hw_params_set_period_size_last().

When period wakeups are disabled, the application must not use any functions that could block on this device. The use of poll should be limited to error cases. The application needs to use an external event or a timer to check the state of the ring buffer and refill it apropriately.

snd_pcm_hw_params_set_periods()

int snd_pcm_hw_params_set_periods	(	snd_pcm_t *	pcm,
		snd_pcm_hw_params_t *	params,
		unsigned int	val,
		int	dir
	)

Restrict a configuration space to contain only one periods count.

Parameters

pcm	PCM handle
params	Configuration space
val	approximate periods per buffer
dir	Sub unit direction

Returns

0 otherwise a negative error code if configuration space would become empty

Wanted exact value is <,=,> val following dir (-1,0,1)

snd_pcm_hw_params_set_periods_first()

int snd_pcm_hw_params_set_periods_first	(	snd_pcm_t *	pcm,
		snd_pcm_hw_params_t *	params,
		unsigned int *	val,
		int *	dir
	)

Restrict a configuration space to contain only its minimum periods count.

Parameters

pcm	PCM handle
params	Configuration space
val	Returned approximate minimum periods per buffer
dir	Sub unit direction

Returns

0 otherwise a negative error code

Actual exact value is <,=,> the approximate one following dir (-1, 0, 1)

snd_pcm_hw_params_set_periods_integer()

int snd_pcm_hw_params_set_periods_integer	(	snd_pcm_t *	pcm,
		snd_pcm_hw_params_t *	params
	)

Restrict a configuration space to contain only integer periods counts.

Parameters

pcm	PCM handle
params	Configuration space

Returns

0 otherwise a negative error code if configuration space would become empty

snd_pcm_hw_params_set_periods_last()

int snd_pcm_hw_params_set_periods_last	(	snd_pcm_t *	pcm,
		snd_pcm_hw_params_t *	params,
		unsigned int *	val,
		int *	dir
	)

Restrict a configuration space to contain only its maximum periods count.

Parameters

pcm	PCM handle
params	Configuration space
val	Returned approximate maximum periods per buffer
dir	Sub unit direction

Returns

0 otherwise a negative error code

Actual exact value is <,=,> the approximate one following dir (-1, 0, 1)

snd_pcm_hw_params_set_periods_max()

int snd_pcm_hw_params_set_periods_max	(	snd_pcm_t *	pcm,
		snd_pcm_hw_params_t *	params,
		unsigned int *	val,
		int *	dir
	)

Restrict a configuration space with a maximum periods count.

Parameters

pcm	PCM handle
params	Configuration space
val	approximate maximum periods per buffer (on return filled with actual maximum)
dir	Sub unit direction (on return filled with actual direction)

Returns

0 otherwise a negative error code if configuration space would become empty

Wanted/actual exact maximum is <,=,> val following dir (-1,0,1)

snd_pcm_hw_params_set_periods_min()

int snd_pcm_hw_params_set_periods_min	(	snd_pcm_t *	pcm,
		snd_pcm_hw_params_t *	params,
		unsigned int *	val,
		int *	dir
	)

Restrict a configuration space with a minimum periods count.

Parameters

pcm	PCM handle
params	Configuration space
val	approximate minimum periods per buffer (on return filled with actual minimum)
dir	Sub unit direction (on return filled with actual direction)

Returns

0 otherwise a negative error code if configuration space would become empty

Wanted/actual exact minimum is <,=,> val following dir (-1,0,1)

snd_pcm_hw_params_set_periods_minmax()

int snd_pcm_hw_params_set_periods_minmax	(	snd_pcm_t *	pcm,
		snd_pcm_hw_params_t *	params,
		unsigned int *	min,
		int *	mindir,
		unsigned int *	max,
		int *	maxdir
	)

Restrict a configuration space to have periods counts in a given range.

Parameters

pcm	PCM handle
params	Configuration space
min	approximate minimum periods per buffer (on return filled with actual minimum)
mindir	Sub unit direction for minimum (on return filled with actual direction)
max	approximate maximum periods per buffer (on return filled with actual maximum)
maxdir	Sub unit direction for maximum (on return filled with actual direction)

Returns

0 otherwise a negative error code if configuration space would become empty

Wanted/actual exact min/max is <,=,> val following dir (-1,0,1)

snd_pcm_hw_params_set_periods_near()

int snd_pcm_hw_params_set_periods_near	(	snd_pcm_t *	pcm,
		snd_pcm_hw_params_t *	params,
		unsigned int *	val,
		int *	dir
	)

Restrict a configuration space to have periods count nearest to a target.

Parameters

pcm	PCM handle
params	Configuration space
val	approximate target periods per buffer / returned chosen approximate target periods per buffer
dir	Sub unit direction

Returns

0 otherwise a negative error code if configuration space is empty

target/chosen exact value is <,=,> val following dir (-1,0,1)

snd_pcm_hw_params_set_rate()

int snd_pcm_hw_params_set_rate	(	snd_pcm_t *	pcm,
		snd_pcm_hw_params_t *	params,
		unsigned int	val,
		int	dir
	)

Restrict a configuration space to contain only one rate.

Parameters

pcm	PCM handle
params	Configuration space
val	approximate rate
dir	Sub unit direction

Returns

0 otherwise a negative error code if configuration space would become empty

Wanted exact value is <,=,> val following dir (-1,0,1)

snd_pcm_hw_params_set_rate_first()

int snd_pcm_hw_params_set_rate_first	(	snd_pcm_t *	pcm,
		snd_pcm_hw_params_t *	params,
		unsigned int *	val,
		int *	dir
	)

Restrict a configuration space to contain only its minimum rate.

Parameters

pcm	PCM handle
params	Configuration space
val	Returned minimum approximate rate
dir	Sub unit direction

Returns

0 otherwise a negative error code

Actual exact value is <,=,> the approximate one following dir (-1, 0, 1)

snd_pcm_hw_params_set_rate_last()

int snd_pcm_hw_params_set_rate_last	(	snd_pcm_t *	pcm,
		snd_pcm_hw_params_t *	params,
		unsigned int *	val,
		int *	dir
	)

Restrict a configuration space to contain only its maximum rate.

Parameters

pcm	PCM handle
params	Configuration space
val	Returned maximum approximate rate
dir	Sub unit direction

Returns

0 otherwise a negative error code

Actual exact value is <,=,> the approximate one following dir (-1, 0, 1)

snd_pcm_hw_params_set_rate_max()

int snd_pcm_hw_params_set_rate_max	(	snd_pcm_t *	pcm,
		snd_pcm_hw_params_t *	params,
		unsigned int *	val,
		int *	dir
	)

Restrict a configuration space with a maximum rate.

Parameters

pcm	PCM handle
params	Configuration space
val	approximate maximum rate (on return filled with actual maximum)
dir	Sub unit direction (on return filled with actual direction)

Returns

0 otherwise a negative error code if configuration space would become empty

Wanted/actual exact maximum is <,=,> val following dir (-1,0,1)

snd_pcm_hw_params_set_rate_min()

int snd_pcm_hw_params_set_rate_min	(	snd_pcm_t *	pcm,
		snd_pcm_hw_params_t *	params,
		unsigned int *	val,
		int *	dir
	)

Restrict a configuration space with a minimum rate.

Parameters

pcm	PCM handle
params	Configuration space
val	approximate minimum rate (on return filled with actual minimum)
dir	Sub unit direction (on return filled with actual direction)

Returns

0 otherwise a negative error code if configuration space would become empty

Wanted/actual exact minimum is <,=,> val following dir (-1,0,1)

snd_pcm_hw_params_set_rate_minmax()

int snd_pcm_hw_params_set_rate_minmax	(	snd_pcm_t *	pcm,
		snd_pcm_hw_params_t *	params,
		unsigned int *	min,
		int *	mindir,
		unsigned int *	max,
		int *	maxdir
	)

Restrict a configuration space to have rates in a given range.

Parameters

pcm	PCM handle
params	Configuration space
min	approximate minimum rate (on return filled with actual minimum)
mindir	Sub unit direction for minimum (on return filled with actual direction)
max	approximate maximum rate (on return filled with actual maximum)
maxdir	Sub unit direction for maximum (on return filled with actual direction)

Returns

0 otherwise a negative error code if configuration space would become empty

Wanted/actual exact min/max is <,=,> val following dir (-1,0,1)

snd_pcm_hw_params_set_rate_near()

int snd_pcm_hw_params_set_rate_near	(	snd_pcm_t *	pcm,
		snd_pcm_hw_params_t *	params,
		unsigned int *	val,
		int *	dir
	)

Restrict a configuration space to have rate nearest to a target.

Parameters

pcm	PCM handle
params	Configuration space
val	approximate target rate / returned approximate set rate
dir	Sub unit direction

Returns

0 otherwise a negative error code if configuration space is empty

target/chosen exact value is <,=,> val following dir (-1,0,1)

Examples

/test/latency.c, and /test/pcm.c.

snd_pcm_hw_params_set_rate_resample()

int snd_pcm_hw_params_set_rate_resample	(	snd_pcm_t *	pcm,
		snd_pcm_hw_params_t *	params,
		unsigned int	val
	)

Restrict a configuration space to contain only real hardware rates.

Parameters

pcm	PCM handle
params	Configuration space
val	0 = disable, 1 = enable (default) rate resampling

Returns

0 otherwise a negative error code

Examples

/test/latency.c, and /test/pcm.c.

snd_pcm_hw_params_set_subformat()

int snd_pcm_hw_params_set_subformat	(	snd_pcm_t *	pcm,
		snd_pcm_hw_params_t *	params,
		snd_pcm_subformat_t	subformat
	)

Restrict a configuration space to contain only one subformat.

Parameters

pcm	PCM handle
params	Configuration space
subformat	subformat value

Returns

0 otherwise a negative error code if configuration space would become empty

snd_pcm_hw_params_set_subformat_first()

int snd_pcm_hw_params_set_subformat_first	(	snd_pcm_t *	pcm,
		snd_pcm_hw_params_t *	params,
		snd_pcm_subformat_t *	subformat
	)

Restrict a configuration space to contain only its first subformat.

Parameters

pcm	PCM handle
params	Configuration space
subformat	Returned subformat

Returns

0 otherwise a negative error code

snd_pcm_hw_params_set_subformat_last()

int snd_pcm_hw_params_set_subformat_last	(	snd_pcm_t *	pcm,
		snd_pcm_hw_params_t *	params,
		snd_pcm_subformat_t *	subformat
	)

Restrict a configuration space to contain only its last subformat.

Parameters

pcm	PCM handle
params	Configuration space
subformat	Returned subformat

Returns

0 otherwise a negative error code

snd_pcm_hw_params_set_subformat_mask()

int snd_pcm_hw_params_set_subformat_mask	(	snd_pcm_t *	pcm,
		snd_pcm_hw_params_t *	params,
		snd_pcm_subformat_mask_t *	mask
	)

Restrict a configuration space to contain only a set of subformats.

Parameters

pcm	PCM handle
params	Configuration space
mask	Subformat mask

Returns

0 otherwise a negative error code

snd_pcm_hw_params_sizeof()

size_t snd_pcm_hw_params_sizeof

(

void

)

get size of snd_pcm_hw_params_t

Returns

size in bytes

snd_pcm_hw_params_supports_audio_ts_type()

int snd_pcm_hw_params_supports_audio_ts_type	(	const snd_pcm_hw_params_t *	params,
		int	type
	)

Check if hardware supports type of audio timestamps.

Parameters

params	Configuration space
type	Audio timestamp type

Return values

0	Hardware doesn't support type of audio timestamps
1	Hardware supports type of audio timestamps

This function should only be called when the configuration space contains a single configuration. Call snd_pcm_hw_params to choose a single configuration from the configuration space.

snd_pcm_hw_params_supports_audio_wallclock_ts()

int snd_pcm_hw_params_supports_audio_wallclock_ts

(

const snd_pcm_hw_params_t *

params

)

Check if hardware supports audio wallclock timestamps.

Parameters

params

Configuration space

Return values

0	Hardware doesn't support audio wallclock timestamps
1	Hardware supports audio wallclock timestamps

This function should only be called when the configuration space contains a single configuration. Call snd_pcm_hw_params to choose a single configuration from the configuration space.

snd_pcm_hw_params_test_access()

int snd_pcm_hw_params_test_access	(	snd_pcm_t *	pcm,
		snd_pcm_hw_params_t *	params,
		snd_pcm_access_t	access
	)

Verify if an access type is available inside a configuration space for a PCM.

Parameters

pcm	PCM handle
params	Configuration space
access	access type

Returns

0 if available a negative error code otherwise

snd_pcm_hw_params_test_buffer_size()

int snd_pcm_hw_params_test_buffer_size	(	snd_pcm_t *	pcm,
		snd_pcm_hw_params_t *	params,
		snd_pcm_uframes_t	val
	)

Verify if a buffer size is available inside a configuration space for a PCM.

Parameters

pcm	PCM handle
params	Configuration space
val	buffer size in frames

Returns

0 if available a negative error code otherwise

Wanted exact value is <,=,> val following dir (-1,0,1)

snd_pcm_hw_params_test_buffer_time()

int snd_pcm_hw_params_test_buffer_time	(	snd_pcm_t *	pcm,
		snd_pcm_hw_params_t *	params,
		unsigned int	val,
		int	dir
	)

Verify if a buffer time is available inside a configuration space for a PCM.

Parameters

pcm	PCM handle
params	Configuration space
val	approximate buffer duration in us
dir	Sub unit direction

Returns

0 if available a negative error code otherwise

Wanted exact value is <,=,> val following dir (-1,0,1)

snd_pcm_hw_params_test_channels()

int snd_pcm_hw_params_test_channels	(	snd_pcm_t *	pcm,
		snd_pcm_hw_params_t *	params,
		unsigned int	val
	)

Verify if a channels count is available inside a configuration space for a PCM.

Parameters

pcm	PCM handle
params	Configuration space
val	channels count

Returns

0 if available a negative error code otherwise

snd_pcm_hw_params_test_format()

int snd_pcm_hw_params_test_format	(	snd_pcm_t *	pcm,
		snd_pcm_hw_params_t *	params,
		snd_pcm_format_t	format
	)

Verify if a format is available inside a configuration space for a PCM.

Parameters

pcm	PCM handle
params	Configuration space
format	format

Returns

0 if available a negative error code otherwise

snd_pcm_hw_params_test_period_size()

int snd_pcm_hw_params_test_period_size	(	snd_pcm_t *	pcm,
		snd_pcm_hw_params_t *	params,
		snd_pcm_uframes_t	val,
		int	dir
	)

Verify if a period size is available inside a configuration space for a PCM.

Parameters

pcm	PCM handle
params	Configuration space
val	approximate period size in frames
dir	Sub unit direction

Returns

0 if available a negative error code otherwise

Wanted exact value is <,=,> val following dir (-1,0,1)

snd_pcm_hw_params_test_period_time()

int snd_pcm_hw_params_test_period_time	(	snd_pcm_t *	pcm,
		snd_pcm_hw_params_t *	params,
		unsigned int	val,
		int	dir
	)

Verify if a period time is available inside a configuration space for a PCM.

Parameters

pcm	PCM handle
params	Configuration space
val	approximate period duration in us
dir	Sub unit direction

Returns

0 if available a negative error code otherwise

Wanted exact value is <,=,> val following dir (-1,0,1)

snd_pcm_hw_params_test_periods()

int snd_pcm_hw_params_test_periods	(	snd_pcm_t *	pcm,
		snd_pcm_hw_params_t *	params,
		unsigned int	val,
		int	dir
	)

Verify if a periods count is available inside a configuration space for a PCM.

Parameters

pcm	PCM handle
params	Configuration space
val	approximate periods per buffer
dir	Sub unit direction

Returns

0 if available a negative error code otherwise

Wanted exact value is <,=,> val following dir (-1,0,1)

snd_pcm_hw_params_test_rate()

int snd_pcm_hw_params_test_rate	(	snd_pcm_t *	pcm,
		snd_pcm_hw_params_t *	params,
		unsigned int	val,
		int	dir
	)

Verify if a rate is available inside a configuration space for a PCM.

Parameters

pcm	PCM handle
params	Configuration space
val	approximate rate
dir	Sub unit direction

Returns

0 if available a negative error code otherwise

Wanted exact value is <,=,> val following dir (-1,0,1)

snd_pcm_hw_params_test_subformat()

int snd_pcm_hw_params_test_subformat	(	snd_pcm_t *	pcm,
		snd_pcm_hw_params_t *	params,
		snd_pcm_subformat_t	subformat
	)

Verify if a subformat is available inside a configuration space for a PCM.

Parameters

pcm	PCM handle
params	Configuration space
subformat	subformat value

Returns

0 if available a negative error code otherwise