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Software Parameters
[PCM Interface]

Defines
#define	snd_pcm_sw_params_alloca(ptr)
	allocate an invalid snd_pcm_sw_params_t using standard alloca
Functions
size_t	snd_pcm_sw_params_sizeof (void)
	get size of snd_pcm_sw_params_t
int	snd_pcm_sw_params_malloc (snd_pcm_sw_params_t **ptr)
	allocate an invalid snd_pcm_sw_params_t using standard malloc
void	snd_pcm_sw_params_free (snd_pcm_sw_params_t *obj)
	frees a previously allocated snd_pcm_sw_params_t
void	snd_pcm_sw_params_copy (snd_pcm_sw_params_t *dst, const snd_pcm_sw_params_t *src)
	copy one snd_pcm_sw_params_t to another
int	snd_pcm_sw_params_set_tstamp_mode (snd_pcm_t *pcm, snd_pcm_sw_params_t *params, snd_pcm_tstamp_t val)
	Set timestamp mode inside a software configuration container.
int	snd_pcm_sw_params_set_sleep_min (snd_pcm_t *pcm, snd_pcm_sw_params_t *params, unsigned int val)
	Set minimum number of ticks to sleep inside a software configuration container.
int	snd_pcm_sw_params_set_avail_min (snd_pcm_t *pcm, snd_pcm_sw_params_t *params, snd_pcm_uframes_t val)
	Set avail min inside a software configuration container.
int	snd_pcm_sw_params_set_xfer_align (snd_pcm_t *pcm, snd_pcm_sw_params_t *params, snd_pcm_uframes_t val)
	Set xfer align inside a software configuration container.
int	snd_pcm_sw_params_set_start_threshold (snd_pcm_t *pcm, snd_pcm_sw_params_t *params, snd_pcm_uframes_t val)
	Set start threshold inside a software configuration container.
int	snd_pcm_sw_params_set_stop_threshold (snd_pcm_t *pcm, snd_pcm_sw_params_t *params, snd_pcm_uframes_t val)
	Set stop threshold inside a software configuration container.
int	snd_pcm_sw_params_set_silence_threshold (snd_pcm_t *pcm, snd_pcm_sw_params_t *params, snd_pcm_uframes_t val)
	Set silence threshold inside a software configuration container.
int	snd_pcm_sw_params_set_silence_size (snd_pcm_t *pcm, snd_pcm_sw_params_t *params, snd_pcm_uframes_t val)
	Set silence size inside a software configuration container.

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Detailed Description

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

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Define Documentation

#define snd_pcm_sw_params_alloca (  ptr    )

allocate an invalid snd_pcm_sw_params_t using standard alloca Parameters: ptr  returned pointer Examples: /test/latency.c, and /test/pcm.c.

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Function Documentation

void snd_pcm_sw_params_copy (  snd_pcm_sw_params_t *    dst, const snd_pcm_sw_params_t *    src )

copy one snd_pcm_sw_params_t to another Parameters: dst  pointer to destination src  pointer to source

void snd_pcm_sw_params_free (  snd_pcm_sw_params_t *    obj )

frees a previously allocated snd_pcm_sw_params_t Parameters: pointer  to object to free

int snd_pcm_sw_params_malloc (  snd_pcm_sw_params_t **    ptr )

allocate an invalid snd_pcm_sw_params_t using standard malloc Parameters: ptr  returned pointer Returns: 0 on success otherwise negative error code

int snd_pcm_sw_params_set_avail_min (  snd_pcm_t *    pcm, snd_pcm_sw_params_t *    params, snd_pcm_uframes_t    val )

Set avail min inside a software configuration container. Parameters: pcm  PCM handle params  Software configuration container val  Minimum avail frames to consider PCM ready Returns: 0 otherwise a negative error code Note: This is similar to setting an OSS wakeup point. The valid values for 'val' are determined by the specific hardware. Most PC sound cards can only accept power of 2 frame counts (i.e. 512, 1024, 2048). You cannot use this as a high resolution timer - it is limited to how often the sound card hardware raises an interrupt. Note that you can greatly improve the reponses using Software Parameters where another timing source is used. Examples: /test/latency.c, and /test/pcm.c.

int snd_pcm_sw_params_set_silence_size (  snd_pcm_t *    pcm, snd_pcm_sw_params_t *    params, snd_pcm_uframes_t    val )

Set silence size inside a software configuration container. Parameters: pcm  PCM handle params  Software configuration container val  Silence size in frames (0 for disabled) Returns: 0 otherwise a negative error code A portion of playback buffer is overwritten with silence when playback underrun is nearer than silence threshold (see snd_pcm_sw_params_set_silence_threshold)

int snd_pcm_sw_params_set_silence_threshold (  snd_pcm_t *    pcm, snd_pcm_sw_params_t *    params, snd_pcm_uframes_t    val )

Set silence threshold inside a software configuration container. Parameters: pcm  PCM handle params  Software configuration container val  Silence threshold in frames Returns: 0 otherwise a negative error code A portion of playback buffer is overwritten with silence (see snd_pcm_sw_params_set_silence_size) when playback underrun is nearer than silence threshold

int snd_pcm_sw_params_set_sleep_min (  snd_pcm_t *    pcm, snd_pcm_sw_params_t *    params, unsigned int    val )

Set minimum number of ticks to sleep inside a software configuration container. Parameters: pcm  PCM handle params  Software configuration container val  Minimum ticks to sleep or 0 to disable the use of tick timer Returns: 0 otherwise a negative error code Examples: /test/latency.c.

int snd_pcm_sw_params_set_start_threshold (  snd_pcm_t *    pcm, snd_pcm_sw_params_t *    params, snd_pcm_uframes_t    val )

Set start threshold inside a software configuration container. Parameters: pcm  PCM handle params  Software configuration container val  Start threshold in frames Returns: 0 otherwise a negative error code PCM is automatically started when playback frames available to PCM are >= threshold or when requested capture frames are >= threshold Examples: /test/latency.c, and /test/pcm.c.

int snd_pcm_sw_params_set_stop_threshold (  snd_pcm_t *    pcm, snd_pcm_sw_params_t *    params, snd_pcm_uframes_t    val )

Set stop threshold inside a software configuration container. Parameters: pcm  PCM handle params  Software configuration container val  Stop threshold in frames Returns: 0 otherwise a negative error code PCM is automatically stopped in SND_PCM_STATE_XRUN state when available frames is >= threshold

int snd_pcm_sw_params_set_tstamp_mode (  snd_pcm_t *    pcm, snd_pcm_sw_params_t *    params, snd_pcm_tstamp_t    val )

Set timestamp mode inside a software configuration container. Parameters: pcm  PCM handle params  Software configuration container val  Timestamp mode Returns: 0 otherwise a negative error code

int snd_pcm_sw_params_set_xfer_align (  snd_pcm_t *    pcm, snd_pcm_sw_params_t *    params, snd_pcm_uframes_t    val )

Set xfer align inside a software configuration container. Parameters: pcm  PCM handle params  Software configuration container val  Chunk size (frames are attempted to be transferred in chunks) Returns: 0 otherwise a negative error code Examples: /test/latency.c, and /test/pcm.c.

size_t snd_pcm_sw_params_sizeof (  void    )

get size of snd_pcm_sw_params_t Returns: size in bytes

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