iOS 最简单的OpenAL播放PCM实时音频
这是拿windows版的移植来的，当然也可以再移植过去。这里简单说一下怎么使用，因为音频播放速率是一定的，那么给openal更新pcm数据包的速率也是一定的，太快了太慢了都会播放异常，openal有pcm数据缓冲，要实时监控缓冲里面剩余数据的多少，少了及时更新数据多了及时阻塞，其中m_numqueued头文件中这个值的大小就是将要播放的缓存的队列的数据数量。这个队列数据缓存太大了播放延迟大，太小了要注意适配不同采样率的音频数据。
我是这样阻塞的，如下：
完整播放器demo ffmpeg+opengl+openal：
http://blog.csdn.net/m0_37677536/article/details/78769362
.h
//
// OpenalPlayer.h
// FFmpeg-project
//
// Created by huizai on 2017/10/26.
// Copyright © 2017年 huizai. All rights reserved.
//
#import .m
//
// OpenalPlayer.m
// FFmpeg-project
//
// Created by huizai on 2017/10/26.
// Copyright © 2017年 huizai. All rights reserved.
//
#import "OpenalPlayer.h"
@implementation OpenalPlayer{
ALCdevice * m_Devicde; //device句柄
ALCcontext * m_Context; //device context
ALuint m_outSourceId; //source id 负责播放
NSLock * lock;
float rate;
}
-(int)initOpenAL{
int ret = 0;
lock = [[NSLock alloc]init];
printf("=======initOpenAl===\n");
rate = 1.0;
m_Devicde = alcOpenDevice(NULL);
if (m_Devicde)
{
//建立声音文本描述
m_Context = alcCreateContext(m_Devicde, NULL);
//设置行为文本描述
alcMakeContextCurrent(m_Context);
}else
ret = -1;
//创建一个source并设置一些属性
alGenSources(1, &m_outSourceId);
alSpeedOfSound(1.0);
alDopplerVelocity(1.0);
alDopplerFactor(1.0);
alSourcef(m_outSourceId, AL_PITCH, 1.0f);
alSourcef(m_outSourceId, AL_GAIN, 1.0f);
alSourcei(m_outSourceId, AL_LOOPING, AL_FALSE);
alSourcef(m_outSourceId, AL_SOURCE_TYPE, AL_STREAMING);
return ret;
}
-(int)updataQueueBuffer{
//播放状态字段
ALint stateVaue = 0;
//获取处理队列，得出已经播放过的缓冲器的数量
alGetSourcei(m_outSourceId, AL_BUFFERS_PROCESSED, &_m_numprocessed);
//获取缓存队列，缓存的队列数量
alGetSourcei(m_outSourceId, AL_BUFFERS_QUEUED, &_m_numqueued);
//获取播放状态，是不是正在播放
alGetSourcei(m_outSourceId, AL_SOURCE_STATE, &stateVaue);
//printf("===statevaue ========================%x\n",stateVaue);
if (stateVaue == AL_STOPPED ||
stateVaue == AL_PAUSED ||
stateVaue == AL_INITIAL)
{
//如果没有数据,或数据播放完了
if (_m_numqueued < _m_numprocessed || _m_numqueued == 0 ||(_m_numqueued == 1 && _m_numprocessed ==1))
{
//停止播放
printf("...Audio Stop\n");
[self stopSound];;
[self cleanUpOpenAL];
return 0;
}
if (stateVaue != AL_PLAYING)
{
[self playSound];
}
}
//将已经播放过的的数据删除掉
while(_m_numprocessed --)
{
ALuint buff;
//更新缓存buffer中的数据到source中
alSourceUnqueueBuffers(m_outSourceId, 1, &buff);
//删除缓存buff中的数据
alDeleteBuffers(1, &buff);
//得到已经播放的音频队列多少块
_m_IsplayBufferSize ++;
}
return 1;
}
-(void)cleanUpOpenAL{
printf("=======cleanUpOpenAL===\n");
alDeleteSources(1, &m_outSourceId);
ALCcontext * Context = alcGetCurrentContext();
// ALCdevice * Devicde = alcGetContextsDevice(Context);
if (Context)
{
alcMakeContextCurrent(NULL);
alcDestroyContext(Context);
m_Context = NULL;
}
alcCloseDevice(m_Devicde);
m_Devicde = NULL;
}
-(void)playSound{
int ret = 0;
alSourcePlay(m_outSourceId);
if((ret = alGetError()) != AL_NO_ERROR)
{
printf("error alcMakeContextCurrent %x\n", ret);
}
}
-(void)stopSound{
alSourceStop(m_outSourceId);
}
-(int)openAudioFromQueue:(char*)data andWithDataSize:(int)dataSize andWithSampleRate:(int) aSampleRate andWithAbit:(int)aBit andWithAchannel:(int)aChannel{
int ret = 0;
//样本数openal的表示方法
ALenum format = 0;
//buffer id 负责缓存,要用局部变量每次数据都是新的地址
ALuint bufferID = 0;
if (_m_datasize == 0 &&
_m_samplerate == 0 &&
_m_bit == 0 &&
_m_channel == 0)
{
if (dataSize != 0 &&
aSampleRate != 0 &&
aBit != 0 &&
aChannel != 0)
{
_m_datasize = dataSize;
_m_samplerate = aSampleRate;
_m_bit = aBit;
_m_channel = aChannel;
_m_oneframeduration = _m_datasize * 1.0 /(_m_bit/8) /_m_channel /_m_samplerate * 1000 ; //计算一帧数据持续时间
}
}
//创建一个buffer
alGenBuffers(1, &bufferID);
if((ret = alGetError()) != AL_NO_ERROR)
{
printf("error alGenBuffers %x \n", ret);
// printf("error alGenBuffers %x : %s\n", ret,alutGetErrorString (ret));
//AL_ILLEGAL_ENUM
//AL_INVALID_VALUE
//#define AL_ILLEGAL_COMMAND 0xA004
//#define AL_INVALID_OPERATION 0xA004
}
if (aBit == 8)
{
if (aChannel == 1)
{
format = AL_FORMAT_MONO8;
}
else if(aChannel == 2)
{
format = AL_FORMAT_STEREO8;
}
}
if( aBit == 16 )
{
if( aChannel == 1 )
{
format = AL_FORMAT_MONO16;
}
if( aChannel == 2 )
{
format = AL_FORMAT_STEREO16;
}
}
//指定要将数据复制到缓冲区中的数据
alBufferData(bufferID, format, data, dataSize,aSampleRate);
if((ret = alGetError()) != AL_NO_ERROR)
{
printf("error alBufferData %x\n", ret);
//AL_ILLEGAL_ENUM
//AL_INVALID_VALUE
//#define AL_ILLEGAL_COMMAND 0xA004
//#define AL_INVALID_OPERATION 0xA004
}
//附加一个或一组buffer到一个source上
alSourceQueueBuffers(m_outSourceId, 1, &bufferID);
if((ret = alGetError()) != AL_NO_ERROR)
{
printf("error alSourceQueueBuffers %x\n", ret);
}
//更新队列数据
ret = [self updataQueueBuffer];
bufferID = 0;
return ret;
}
- (void)setM_volume:(float)m_volume{
self.m_volume = m_volume;
alSourcef(m_outSourceId,AL_GAIN,m_volume);
}
- (float)m_volume{
return self.m_volume;
}
-(void)setPlayRate:(double)playRate{
alSourcef(m_outSourceId, AL_PITCH, playRate);
}
@end