libsent/src/adin/adin_mic_linux_alsa.c File Reference

Microphone input on Linux/ALSA. More...

#include <sent/stddefs.h>
#include <sent/adin.h>
#include <sys/ioctl.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <alsa/asoundlib.h>

Go to the source code of this file.

Functions
boolean	adin_mic_standby (int sfreq, void *dummy)
	Device initialization: check device capability and open for recording.
static int	xrun_recovery (snd_pcm_t *handle, int err)
	Error recovery when PCM buffer underrun or suspend.
boolean	adin_mic_begin ()
	Start recording.
boolean	adin_mic_end ()
	Stop recording.
int	adin_mic_read (SP16 *buf, int sampnum)
	Read samples from device.
Variables
static snd_pcm_t *	handle
	Audio handler.
static snd_pcm_hw_params_t *	hwparams
	Pointer to device hardware parameters.
static char *	pcm_name = "hw:0,0"
	Name of the PCM device.
static boolean	need_swap
	Whether samples need byte swap.
static int	latency = 32
	Lantency time in msec. You can override this value by specifying environment valuable "LATENCY_MSEC".
static struct pollfd *	ufds
	Poll descriptor.
static int	count
	Poll descriptor count.

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Detailed Description

Microphone input on Linux/ALSA.

Low level I/O functions for microphone input on Linux using Advanced Linux Sound Architechture (ALSA) API, developed on version 0.9.x. If you want to use this API, please specify "--with-mictype=alsa" options at compilation time to configure script.

Julius does not alter any mixer device setting at all on Linux. You should configure the mixer for recording source (mic/line) and recording volume correctly using other audio tool such as alsamixer.

Note that sound card should support 16bit monaural recording, and multiple cards are not supported (in that case the first one will be used).

See also:

http://www.alsa-project.org/

Author:

Akinobu LEE

Date:

Sun Feb 13 16:18:26 2005

Revision

1.1.1.1

Definition in file adin_mic_linux_alsa.c.

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Function Documentation

boolean adin_mic_standby	(	int	sfreq,
		void *	dummy
	)

Device initialization: check device capability and open for recording.

Connection initialization: check connectivity and open for recording.

Parameters:

	sfreq	[in] required sampling frequency.
	dummy	[in] a dummy data

Returns:

TRUE on success, FALSE on failure.

Definition at line 81 of file adin_mic_linux_alsa.c.

static int xrun_recovery	(	snd_pcm_t *	handle,
		int	err
	)			[static]

Error recovery when PCM buffer underrun or suspend.

Parameters:

	handle	[in] audio handler
	err	[in] error code

Returns:

0 on success, otherwise the given errno.

Definition at line 287 of file adin_mic_linux_alsa.c.

boolean adin_mic_begin

(

)

Start recording.

Returns:

TRUE on success, FALSE on failure.

Definition at line 313 of file adin_mic_linux_alsa.c.

boolean adin_mic_end

(

)

Stop recording.

Returns:

TRUE on success, FALSE on failure.

Definition at line 359 of file adin_mic_linux_alsa.c.

int adin_mic_read	(	SP16 *	buf,
		int	sampnum
	)

Read samples from device.

Read samples from the daemon.

Try to read sampnum samples and returns actual number of recorded samples currently available. This function will block until at least one sample can be obtained.

Parameters:

	buf	[out] samples obtained in this function
	sampnum	[in] wanted number of samples to be read

Returns:

actural number of read samples, -2 if an error occured.

Definition at line 377 of file adin_mic_linux_alsa.c.

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