Hardware Parameters
[PCM Interface]

Defines

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

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.
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.
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.
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.
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.
int snd_pcm_hw_params_is_monotonic (const snd_pcm_hw_params_t *params)
 Check, if timestamps are monotonic for given configuration.
int snd_pcm_hw_params_can_overrange (const snd_pcm_hw_params_t *params)
 Check, if hardware supports overrange detection.
int snd_pcm_hw_params_can_pause (const snd_pcm_hw_params_t *params)
 Check, if hardware supports pause.
int snd_pcm_hw_params_can_resume (const snd_pcm_hw_params_t *params)
 Check, if hardware supports resume.
int snd_pcm_hw_params_is_half_duplex (const snd_pcm_hw_params_t *params)
 Check, if hardware does half-duplex only.
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).
int snd_pcm_hw_params_can_sync_start (const snd_pcm_hw_params_t *params)
 Check, if hardware supports synchronized start with sample resolution.
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.
int snd_pcm_hw_params_get_sbits (const snd_pcm_hw_params_t *params)
 Get sample resolution info from a configuration space.
int snd_pcm_hw_params_get_fifo_size (const snd_pcm_hw_params_t *params)
 Get hard are FIFO size info from a configuration space.
size_t snd_pcm_hw_params_sizeof (void)
 get size of snd_pcm_hw_params_t
int snd_pcm_hw_params_malloc (snd_pcm_hw_params_t **ptr)
 allocate an invalid snd_pcm_hw_params_t using standard malloc
void snd_pcm_hw_params_free (snd_pcm_hw_params_t *obj)
 frees a previously allocated snd_pcm_hw_params_t
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
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
int snd_pcm_hw_params_get_channels (const snd_pcm_hw_params_t *params, unsigned int *val)
 Extract channels from a configuration space.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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 accessible from outside.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.

Detailed Description

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


Define Documentation

#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

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
Examples:
/test/latency.c, and /test/pcm.c.
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
Returns:
Boolean value
Return values:
0 Hardware doesn't support sample-resolution mmap
1 Hardware supports sample-resolution mmap

The return value is always one when given configuration is not exactly one. Usually, snd_pcm_hw_params() function chooses one configuration from the configuration space.

int snd_pcm_hw_params_can_overrange ( const snd_pcm_hw_params_t params  ) 

Check, if hardware supports overrange detection.

Parameters:
params Configuration space
Returns:
Boolean value
Return values:
0 Hardware doesn't support overrange detection
1 Hardware supports overrange detection

It is not allowed to call this function when given configuration is not exactly one. Usually, snd_pcm_hw_params() function chooses one configuration from the configuration space.

int snd_pcm_hw_params_can_pause ( const snd_pcm_hw_params_t params  ) 

Check, if hardware supports pause.

Parameters:
params Configuration space
Returns:
Boolean value
Return values:
0 Hardware doesn't support pause
1 Hardware supports pause

It is not allowed to call this function when given configuration is not exactly one. Usually, snd_pcm_hw_params() function chooses one configuration from the configuration space.

int snd_pcm_hw_params_can_resume ( const snd_pcm_hw_params_t params  ) 

Check, if hardware supports resume.

Parameters:
params Configuration space
Returns:
Boolean value
Return values:
0 Hardware doesn't support resume
1 Hardware supports resume

It is not allowed to call this function when given configuration is not exactly one. Usually, snd_pcm_hw_params() function chooses one configuration from the configuration space.

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
Returns:
Boolean value
Return values:
0 Hardware doesn't support synchronized start
1 Hardware supports synchronized start

It is not allowed to call this function when given configuration is not exactly one. Usually, snd_pcm_hw_params() function chooses one configuration from the configuration space.

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.
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
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 not exactly one is present
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
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 not exactly one is present
Examples:
/test/latency.c, and /test/pcm.c.
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)

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
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 not exactly one is present

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

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)

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)

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 not exactly one is present
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
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
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
int snd_pcm_hw_params_get_fifo_size ( const snd_pcm_hw_params_t params  ) 

Get hard are 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

It is not allowed to call this function when given configuration is not exactly one. Usually, snd_pcm_hw_params() function chooses one configuration from the configuration space.

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 not exactly one is present
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
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 not exactly one is present
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 not exactly one is present

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

Examples:
/test/latency.c, and /test/pcm.c.
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)

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)

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 not exactly one is present

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

Examples:
/test/latency.c.
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)

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)

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 not exactly one is present

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

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)

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)

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 not exactly one is present

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

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)

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)

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

It is not allowed to call this function when given configuration is not exactly one. Usually, snd_pcm_hw_params() function chooses one configuration from the configuration space.

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
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

It is not allowed to call this function when given configuration is not exactly one. Usually, snd_pcm_hw_params() function chooses one configuration from the configuration space.

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 not exactly one is present
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
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
Returns:
Boolean value
Return values:
0 Hardware doesn't do double buffering for data transfers
1 Hardware does double buffering for data transfers

It is not allowed to call this function when given configuration is not exactly one. Usually, snd_pcm_hw_params() function chooses one configuration from the configuration space.

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
Returns:
Boolean value
Return values:
0 Hardware doesn't block transfers
1 Hardware does block transfers

It is not allowed to call this function when given configuration is not exactly one. Usually, snd_pcm_hw_params() function chooses one configuration from the configuration space.

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
Returns:
Boolean value
Return values:
0 Hardware doesn't do double buffering for start/stop
1 Hardware does double buffering for start/stop

It is not allowed to call this function when given configuration is not exactly one. Usually, snd_pcm_hw_params() function chooses one configuration from the configuration space.

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
Returns:
Boolean value
Return values:
0 Hardware doesn't do half-duplex
1 Hardware does half-duplex

It is not allowed to call this function when given configuration is not exactly one. Usually, snd_pcm_hw_params() function chooses one configuration from the configuration space.

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
Returns:
Boolean value
Return values:
0 Hardware doesn't do joint-duplex
1 Hardware does joint-duplex

It is not allowed to call this function when given configuration is not exactly one. Usually, snd_pcm_hw_params() function chooses one configuration from the configuration space.

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
Returns:
Boolean value
Return values:
0 Device doesn't do monotomic timestamps
1 Device does monotonic timestamps

It is not allowed to call this function when given configuration is not exactly one. Usually, snd_pcm_hw_params() function chooses one configuration from the configuration space.

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
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.
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
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
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
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)

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
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
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
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
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
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.
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)

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)

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)

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)

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)

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)

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.
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.
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
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
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
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
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
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
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 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
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.
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
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
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
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)

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)

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
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)

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)

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)

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)

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.
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)

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)

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
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)

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)

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)

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.
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)

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)

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
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)

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)

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)

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)

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)

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)

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)

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)

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)

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)

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)

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.
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.
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
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
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
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
size_t snd_pcm_hw_params_sizeof ( void   ) 

get size of snd_pcm_hw_params_t

Returns:
size in bytes
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
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)

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)

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
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
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)

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)

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)

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)

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
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