audio_loopback.c File Reference

#include <unistd.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <pthread.h>
#include <stdint.h>
#include <semaphore.h>
#include "audio_loopback.h"
#include "utility.h"

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Data Structures
struct	audio_loopback_ts
Enumerations
enum	audio_loopback_thread_state_te { AUDIO_LOOPBACK_STOP, AUDIO_LOOPBACK_RUN }
Functions
static void	audio_loopback_thr (void *param)
static void	audio_loopback_convert_thr (void *param)
static void	audio_loopback_trigger (void)
int32_t	audio_loopback_start (te_audio_device_types device_type, const char *device_name, uint32_t segment_size, int32_t sample_frequency)
int32_t	audio_loopback_stop (void)
void	audio_loopback_feed (const double *src)
Variables
static audio_loopback_ts	loopback
static pthread_cond_t	write_segment_cond [AUDIO_BUFFER_SEGMENTS] = {PTHREAD_COND_INITIALIZER, PTHREAD_COND_INITIALIZER}
static pthread_mutex_t	write_segment_mutex [AUDIO_BUFFER_SEGMENTS] = {PTHREAD_MUTEX_INITIALIZER, PTHREAD_MUTEX_INITIALIZER}
static sem_t	loopback_trigger

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Enumeration Type Documentation

enum audio_loopback_thread_state_te

Audio loopback thread states.

Enumerator:

AUDIO_LOOPBACK_STOP
AUDIO_LOOPBACK_RUN

Definition at line 38 of file audio_loopback.c.

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Function Documentation

static void audio_loopback_convert_thr

(

void *

param

)

[static]

Definition at line 159 of file audio_loopback.c.

References AUDIO_BUFFER_SEGMENTS, audio_loopback_ts::audio_data, audio_data, audio_loopback_ts::audio_device, audio_double2raw(), AUDIO_LOOPBACK_RUN, audio_loopback_trigger(), BUFFER_SEGMENT_1, audio_loopback_ts::dst_samples, audio_loopback_ts::run, write_segment_cond, and write_segment_mutex.

Referenced by audio_loopback_start().

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void audio_loopback_feed

(

const double *

src

)

Used to copy audio data (sound) to the loopback device

Parameters:

src

Pointer to the source audio data (usually filtered).

Definition at line 121 of file audio_loopback.c.

References AUDIO_BUFFER_SEGMENTS, audio_loopback_ts::audio_data, BUFFER_SEGMENT_1, audio_loopback_ts::dst_samples, and write_segment_cond.

int32_t audio_loopback_start	(	te_audio_device_types	device_type,
		const char *	device_name,
		uint32_t	segment_size,
		int32_t	sample_frequency
	)

Starts the audio loopback device.

Parameters:

	device_type	Audio device type
	device_name	Audio device name
	segment_size	Number of samples per segment
	sample_frequency	Sample frequency in Hertz

Returns:

If successful 0, else non-zero.

Todo:

Need to test for full-duplex audio device capability before actually starting.

Definition at line 82 of file audio_loopback.c.

References AUDIO_BUFFER_SEGMENTS, audio_create(), audio_loopback_ts::audio_data, audio_loopback_ts::audio_device, AUDIO_DEVICE_PLAY, audio_device_samples_get(), audio_init(), audio_loopback_convert_thr(), AUDIO_LOOPBACK_RUN, audio_loopback_thr(), audio_open(), audio_loopback_ts::convert_id, audio_loopback_ts::dst_samples, loopback_trigger, audio_loopback_ts::play_id, audio_loopback_ts::run, and audio_loopback_ts::src_samples.

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int32_t audio_loopback_stop

(

void

)

Stop and frees the audio loopback device

Definition at line 110 of file audio_loopback.c.

References audio_loopback_ts::audio_data, audio_destroy(), audio_loopback_ts::audio_device, AUDIO_LOOPBACK_STOP, audio_loopback_ts::convert_id, audio_loopback_ts::play_id, and audio_loopback_ts::run.

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static void audio_loopback_thr

(

void *

param

)

[static]

Definition at line 137 of file audio_loopback.c.

References AUDIO_BUFFER_SEGMENTS, audio_loopback_ts::audio_device, AUDIO_LOOPBACK_RUN, audio_play(), BUFFER_SEGMENT_1, loopback_trigger, audio_loopback_ts::run, and write_segment_cond.

Referenced by audio_loopback_start().

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static void audio_loopback_trigger

(

void

)

[static]

Definition at line 105 of file audio_loopback.c.

References loopback_trigger.

Referenced by audio_loopback_convert_thr().

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Variable Documentation

audio_loopback_ts loopback [static]

Definition at line 66 of file audio_loopback.c.

sem_t loopback_trigger [static]

Definition at line 69 of file audio_loopback.c.

Referenced by audio_loopback_start(), audio_loopback_thr(), and audio_loopback_trigger().

pthread_cond_t write_segment_cond[AUDIO_BUFFER_SEGMENTS] = {PTHREAD_COND_INITIALIZER, PTHREAD_COND_INITIALIZER} [static]

Definition at line 67 of file audio_loopback.c.

Referenced by audio_loopback_convert_thr(), audio_loopback_feed(), and audio_loopback_thr().

pthread_mutex_t write_segment_mutex[AUDIO_BUFFER_SEGMENTS] = {PTHREAD_MUTEX_INITIALIZER, PTHREAD_MUTEX_INITIALIZER} [static]

Definition at line 68 of file audio_loopback.c.

Referenced by audio_loopback_convert_thr().