Simple setup functions

Files
file	/home/abuild/rpmbuild/BUILD/alsa-1.2.15.3-build/alsa-lib-1.2.15.3/src/pcm/pcm_simple.c
	PCM Simple Interface.

Enumerations
enum	snd_spcm_latency_t { SND_SPCM_LATENCY_STANDARD = 0 , SND_SPCM_LATENCY_MEDIUM , SND_SPCM_LATENCY_REALTIME }
enum	snd_spcm_xrun_type_t { SND_SPCM_XRUN_IGNORE = 0 , SND_SPCM_XRUN_STOP }
enum	snd_spcm_duplex_type_t { SND_SPCM_DUPLEX_LIBERAL = 0 , SND_SPCM_DUPLEX_PEDANTIC }

Functions
int	snd_spcm_init (snd_pcm_t *pcm, unsigned int rate, unsigned int channels, snd_pcm_format_t format, snd_pcm_subformat_t subformat, snd_spcm_latency_t latency, snd_pcm_access_t _access, snd_spcm_xrun_type_t xrun_type)
	Set up a simple PCM.
int	snd_spcm_init_duplex (snd_pcm_t *playback_pcm, snd_pcm_t *capture_pcm, unsigned int rate, unsigned int channels, snd_pcm_format_t format, snd_pcm_subformat_t subformat, snd_spcm_latency_t latency, snd_pcm_access_t _access, snd_spcm_xrun_type_t xrun_type, snd_spcm_duplex_type_t duplex_type)
	Initialize simple PCMs in the duplex mode.
int	snd_spcm_init_get_params (snd_pcm_t *pcm, unsigned int *rate, snd_pcm_uframes_t *buffer_size, snd_pcm_uframes_t *period_size)
	Get the set up of simple PCM.

Detailed Description

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

Enumeration Type Documentation

snd_spcm_duplex_type_t

enum snd_spcm_duplex_type_t

Simple PCM duplex type

Enumerator
SND_SPCM_DUPLEX_LIBERAL	liberal duplex - the buffer and period sizes might not match
SND_SPCM_DUPLEX_PEDANTIC	pedantic duplex - the buffer and period sizes MUST match

snd_spcm_latency_t

enum snd_spcm_latency_t

Simple PCM latency type

Enumerator
SND_SPCM_LATENCY_STANDARD	standard latency - for standard playback or capture (estimated latency in one direction 350ms)
SND_SPCM_LATENCY_MEDIUM	medium latency - software phones etc. (estimated latency in one direction maximally 25ms
SND_SPCM_LATENCY_REALTIME	realtime latency - realtime applications (effect processors etc.) (estimated latency in one direction 5ms and better)

snd_spcm_xrun_type_t

enum snd_spcm_xrun_type_t

Simple PCM xrun type

Enumerator
SND_SPCM_XRUN_IGNORE	driver / library will ignore all xruns, the stream runs forever
SND_SPCM_XRUN_STOP	driver / library stops the stream when an xrun occurs

Function Documentation

snd_spcm_init()

int snd_spcm_init	(	snd_pcm_t *	pcm,
		unsigned int	rate,
		unsigned int	channels,
		snd_pcm_format_t	format,
		snd_pcm_subformat_t	subformat,
		snd_spcm_latency_t	latency,
		snd_pcm_access_t	access,
		snd_spcm_xrun_type_t	xrun_type )

Set up a simple PCM.

Parameters

pcm	PCM handle
rate	Sample rate
channels	Number of channels
format	PCM format
subformat	PCM subformat
latency	Latency type
access	PCM acceess type
xrun_type	XRUN type

Returns

0 if successful, or a negative error code

Warning

The simple PCM API may be broken in the current release.

snd_spcm_init_duplex()

int snd_spcm_init_duplex	(	snd_pcm_t *	playback_pcm,
		snd_pcm_t *	capture_pcm,
		unsigned int	rate,
		unsigned int	channels,
		snd_pcm_format_t	format,
		snd_pcm_subformat_t	subformat,
		snd_spcm_latency_t	latency,
		snd_pcm_access_t	access,
		snd_spcm_xrun_type_t	xrun_type,
		snd_spcm_duplex_type_t	duplex_type )

Initialize simple PCMs in the duplex mode.

Parameters

playback_pcm	PCM handle for playback
capture_pcm	PCM handle for capture
rate	Sample rate
channels	Number of channels
format	PCM format
subformat	PCM subformat
latency	Latency type
access	PCM acceess type
xrun_type	XRUN type
duplex_type	Duplex mode

Returns

0 if successful, or a negative error code

Warning

The simple PCM API may be broken in the current release.

snd_spcm_init_get_params()

int snd_spcm_init_get_params	(	snd_pcm_t *	pcm,
		unsigned int *	rate,
		snd_pcm_uframes_t *	buffer_size,
		snd_pcm_uframes_t *	period_size )

Get the set up of simple PCM.

Parameters

pcm	PCM handle
rate	Pointer to store the current sample rate
buffer_size	Pointer to store the current buffer size
period_size	Pointer to store the current period size

Returns

0 if successful, or a negative error code

Warning

The simple PCM API may be broken in the current release.