音频采集会得到格式为CMSampleBufferRef的音频包，音频推流一般把音频流转换成flv格式
（1）将音频流CMSampleBufferRef转换成PCM data
- (NSData *)convertAudioSmapleBufferToPcmData:(CMSampleBufferRef) audioSample{
//获取数据大小
NSInteger audioDataSize =CMSampleBufferGetTotalSampleSize(audioSample);
//分配数据空间
int8_t * audio_data =aw_alloc((int32_t)audioDataSize);
//创建CMBlockBufferRef，获取PCM数据
CMBlockBufferRef dataBuffer =CMSampleBufferGetDataBuffer(audioSample);
//将数据copy至分配的内存中
CMBlockBufferCopyDataBytes(dataBuffer,0, audioDataSize, audio_data);
//返回PCM data
return [NSData dataWithBytesNoCopy:audio_data length:audioDataSize];
}
（2）将音频PCM data编码成acc格式并合成为flv
- (aw_flv_audio_tag*)encodePCMDataToFlvTag:(NSData*)pcmData{
self.curFramePcmData= pcmData;
AudioBufferList outAudioBufferList = {0};
outAudioBufferList.mNumberBuffers=1;
outAudioBufferList.mBuffers[0].mNumberChannels = (uint32_t)self.audioConfig.channelCount;
outAudioBufferList.mBuffers[0].mDataByteSize = self.aMaxOutputFrameSize;
outAudioBufferList.mBuffers[0].mData = malloc(self.aMaxOutputFrameSize);
uint32_t outputDataPacketSize =1;
OSStatus status =AudioConverterFillComplexBuffer(_aConverter,aacEncodeInputDataProc, (__bridgevoid*_Nullable)(self), &outputDataPacketSize, &outAudioBufferList,NULL);
if(status == noErr) {
NSData * rawAAC = [NSDatadataWithBytesNoCopy: outAudioBufferList.mBuffers[0].mDatalength:outAudioBufferList.mBuffers[0].mDataByteSize];
self.manager.timestamp += 1024*1000/self.audioConfig.sampleRate;
return aw_encoder_create_audio_tag((int8_t*)rawAAC.bytes, rawAAC.length, (uint32_t)self.manager.timestamp, &_faacConfig);
}else {
NSLog(@"aac编码错误");
}
return NULL;
}