pa_linux_alsa.h File Reference

ALSA-specific PortAudio API extension header file. More...

#include "portaudio.h"

Go to the source code of this file.

Data Structures
struct	PaAlsaStreamInfo

Typedefs
typedef struct PaAlsaStreamInfo	PaAlsaStreamInfo

Functions
void	PaAlsa_InitializeStreamInfo (PaAlsaStreamInfo *info)
void	PaAlsa_EnableRealtimeScheduling (PaStream *s, int enable)
PaError	PaAlsa_GetStreamInputCard (PaStream *s, int *card)
PaError	PaAlsa_GetStreamOutputCard (PaStream *s, int *card)
PaError	PaAlsa_SetNumPeriods (int numPeriods)
PaError	PaAlsa_SetRetriesBusy (int retries)
void	PaAlsa_SetLibraryPathName (const char *pathName)

Detailed Description

ALSA-specific PortAudio API extension header file.

Typedef Documentation

typedef struct PaAlsaStreamInfo PaAlsaStreamInfo

Function Documentation

void PaAlsa_EnableRealtimeScheduling	(	PaStream *	s,
		int	enable
	)

Instruct whether to enable real-time priority when starting the audio thread.

If this is turned on by the stream is started, the audio callback thread will be created with the FIFO scheduling policy, which is suitable for realtime operation.

References PaAlsaStream::rtSched.

PaError PaAlsa_GetStreamInputCard	(	PaStream *	s,
		int *	card
	)

Get the ALSA-lib card index of this stream's input device.

References alsa_snd_pcm_info_alloca, PaAlsaStream::capture, PA_ENSURE, PA_UNLESS, paDeviceUnavailable, paNoError, and PaAlsaStreamComponent::pcm.

PaError PaAlsa_GetStreamOutputCard	(	PaStream *	s,
		int *	card
	)

Get the ALSA-lib card index of this stream's output device.

References alsa_snd_pcm_info_alloca, PA_ENSURE, PA_UNLESS, paDeviceUnavailable, paNoError, PaAlsaStreamComponent::pcm, and PaAlsaStream::playback.

void PaAlsa_InitializeStreamInfo

(

PaAlsaStreamInfo *

info

)

Initialize host API specific structure, call this before setting relevant attributes.

References PaAlsaStreamInfo::deviceString, PaAlsaStreamInfo::hostApiType, paALSA, PaAlsaStreamInfo::size, and PaAlsaStreamInfo::version.

void PaAlsa_SetLibraryPathName

(

const char *

pathName

)

Set the path and name of ALSA library file if PortAudio is configured to load it dynamically (see PA_ALSA_DYNAMIC). This setting will overwrite the default name set by PA_ALSA_PATHNAME define.

Parameters

pathName

Full path with filename. Only filename can be used, but dlopen() will lookup default searchable directories (/usr/lib;/usr/local/lib) then.

PaError PaAlsa_SetNumPeriods

(

int

numPeriods

)

Set the number of periods (buffer fragments) to configure devices with.

By default the number of periods is 4, this is the lowest number of periods that works well on the author's soundcard.

Parameters

numPeriods

The number of periods.

References paNoError.

PaError PaAlsa_SetRetriesBusy

(

int

retries

)

Set the maximum number of times to retry opening busy device (sleeping for a short interval inbetween).

References paNoError.