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audio_macosx.c
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audio_macosx.c
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/*
* macosx audio output
*
* (c) 2005 bl0rg.net
*
* ripped from audio_macosx.c from mpg123, originally by
* guillaume.outters@free.fr, and from libao macosx plugin
* by Timothy Wood
*/
#include <CoreAudio/AudioHardware.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <mad.h>
#include "audio_macosx_rb.h"
#include "error.h"
#include "audio.h"
#define AUDIO_BUFFER_SIZE 1152 * 2
typedef struct audio_s {
AudioDeviceID device;
unsigned long channels;
unsigned long samplerate;
rb_t rb;
} audio_t;
static audio_t audio;
static int audio_initialized = 0;
static int audio_started = 0;
/* audio_play_proc has to be thread safe */
static OSStatus audio_play_proc(AudioDeviceID inDevice,
const AudioTimeStamp *inNow,
const AudioBufferList *inInputData,
const AudioTimeStamp *inInputTime,
AudioBufferList *outOutputData,
const AudioTimeStamp *inOutputTime,
void *inClientData) {
int i;
for(i = 0; i < outOutputData->mNumberBuffers; i++) {
AudioBuffer *buffer = outOutputData->mBuffers + i;
if ((buffer->mDataByteSize / sizeof(float)) != (1152 * 2)) {
memset(buffer->mData, 0, 1152 * 2 * sizeof(float));
continue;
}
int ret;
ret = rb_dequeue(&audio.rb, buffer->mData, 1152 * 2);
if (ret == 0)
memset(buffer->mData, 0, 1152 * 2 * sizeof(float));
}
return 0;
}
static int audio_init(error_t *error) {
UInt32 size;
int ret;
AudioStreamBasicDescription format;
UInt32 byte_count;
/* get device */
size = sizeof(audio.device);
ret = AudioHardwareGetProperty(kAudioHardwarePropertyDefaultOutputDevice,
&size, &audio.device);
if (ret != 0) {
error_set(error, "Could not get default audio device");
return 0;
}
if (audio.device == kAudioDeviceUnknown) {
error_set(error, "Unknown audio device");
return 0;
}
/* check that the format is pcm */
size = sizeof(format);
ret = AudioDeviceGetProperty(audio.device, 0, false,
kAudioDevicePropertyStreamFormat,
&size, &format);
if (ret != 0) {
error_set(error, "Could not get the stream format");
return 0;
}
if (format.mFormatID != kAudioFormatLinearPCM) {
error_set(error, "The output device is not using PCM format");
return 0;
}
/* set the buffer size, channels, samplerate */
/* XXX channels, samplerate */
size = sizeof(byte_count);
ret = AudioDeviceGetProperty(audio.device, 0, false,
kAudioDevicePropertyBufferSize,
&size, &byte_count);
if (ret) {
error_set(error, "Could not get the buffer size");
return 0;
}
byte_count = 1152 * 2 * sizeof(float);
ret = AudioDeviceSetProperty(audio.device, NULL, 0, false,
kAudioDevicePropertyBufferSize,
size, &byte_count);
if (ret) {
error_set(error, "Could not set the buffer size");
return 0;
}
/* initialize the ring buffer */
rb_init(&audio.rb);
ret = AudioDeviceAddIOProc(audio.device, audio_play_proc, NULL);
if (ret) {
error_set(error, "Could not start the IO proc");
return 0;
}
audio_initialized = 1;
return 1;
}
static inline
float mad_scale_float(mad_fixed_t sample) {
return (float)(sample/(float)(1L << MAD_F_FRACBITS));
}
static inline
signed int mad_scale(mad_fixed_t sample)
{
/* round */
sample += (1L << (MAD_F_FRACBITS - 16));
/* clip */
if (sample >= MAD_F_ONE)
sample = MAD_F_ONE - 1;
else if (sample < -MAD_F_ONE)
sample = -MAD_F_ONE;
/* quantize */
return sample >> (MAD_F_FRACBITS + 1 - 16);
}
int audio_write(struct mad_pcm *pcm, error_t *error) {
if (!audio_initialized) {
audio.channels = pcm->channels;
audio.samplerate = pcm->samplerate;
if (!audio_init(error)) {
error_prepend(error, "Could not initialize audio");
return 0;
}
}
if ((audio.channels != pcm->channels) ||
(audio.samplerate != pcm->samplerate)) {
/* XXX */
error_set(error, "Changing the audio parameters is not supported");
return 0;
}
if (pcm->length != 1152) {
error_printf(error, "Unknown number of samples in the mad buffer: %d",
pcm->length);
return 0;
}
if (pcm->channels != 2) {
error_set(error, "Only stereo PCM data supported");
return 0;
}
int ret;
float buf[1152 * pcm->channels];
float *ptr = buf;
int i;
mad_fixed_t const *left_ch, *right_ch;
left_ch = pcm->samples[0];
right_ch = pcm->samples[1];
for (i = 0; i < pcm->length; i++) {
signed int sample;
*ptr++ = mad_scale(*left_ch++) / 32768.0;
*ptr++ = mad_scale(*right_ch++) / 32768.0;
}
ret = rb_enqueue(&audio.rb, buf, 1152 * pcm->channels);
if (ret == 0) {
error_set(error, "Could not enqueue the PCM samples");
return 0;
}
if (!audio_started) {
ret = AudioDeviceStart(audio.device, audio_play_proc);
if (ret) {
error_set(error, "Could not start the audio playback");
return 0;
}
audio_started = 1;
}
return 1;
}
int audio_close(error_t *error) {
int ret;
if (audio_started) {
ret = AudioDeviceStop(audio.device, audio_play_proc);
if (ret) {
error_set(error, "Could not stop audio playback");
return 0;
}
audio_started = 0;
}
if (audio_initialized) {
ret = AudioDeviceRemoveIOProc(audio.device, audio_play_proc);
if (ret) {
error_set(error, "Could not remove the IOProc");
return 0;
}
audio_initialized = 0;
}
rb_destroy(&audio.rb);
return 1;
}