呼叫AudioUnitRender之外呈现回调方法

Question

取样类似的项目MixerHost，我想混合输出流写入到文件而不是到speakers.So我用kAudioUnitSubType_GenericOutput，并呼吁：

CheckError(AudioUnitInitialize(mixerUnit), "AudioUnitInitialize mixerUnit"); 
CheckError(AudioUnitInitialize(ioUnit), "AudioUnitInitialize iOUnit"); 
CheckError(AudioOutputUnitStart(ioUnit), "AudioOutputUnitStart iOUnit"); 

AudioUnitRenderActionFlags ioActionFlags = 0; 
AudioTimeStamp inTimeStamp; 
memset(&inTimeStamp, 0, sizeof(AudioTimeStamp)); 
inTimeStamp.mFlags = kAudioTimeStampSampleTimeValid; 
UInt32 inOutputBusNumber = 0; 
UInt32 inNumberFrames = 100; 
AudioBuffer buffer; 
buffer.mNumberChannels = 2; 
buffer.mDataByteSize = inNumberFrames*2; 
buffer.mData = malloc(inNumberFrames*2); 
AudioBufferList ioData; 
ioData.mNumberBuffers = 1; 
ioData.mBuffers[0] = buffer; 
CheckError(AudioUnitRender(ioUnit, 
          &ioActionFlags, 
          &inTimeStamp, 
          inOutputBusNumber, 
          inNumberFrames, 
          &ioData), 
      "AudioUnitRender"); 

错误：AudioUnitRender（-50），请告诉我正确的方法来调用AudioUnitRender（）

iluvcapra是正确的，我改变了它的工作原理：

AudioUnitRenderActionFlags flags = 0; 
AudioTimeStamp inTimeStamp; 
memset(&inTimeStamp, 0, sizeof(AudioTimeStamp)); 
inTimeStamp.mFlags = kAudioTimeStampSampleTimeValid; 
UInt32 busNumber = 0; 
UInt32 numberFrames = 100; 

int channelCount = 2; 
AudioBufferList *bufferList = (AudioBufferList*)malloc(sizeof(AudioBufferList)+sizeof(AudioBuffer)*(channelCount-1)); 
bufferList->mNumberBuffers = channelCount; 
for (int i=0; i<channelCount; i++) { 
    AudioBuffer buffer = {0}; 
    buffer.mNumberChannels = 1; 
    buffer.mDataByteSize = numberFrames*sizeof(AudioUnitSampleType); 
    buffer.mData = calloc(numberFrames, sizeof(AudioUnitSampleType)); 

    bufferList->mBuffers[i] = buffer; 

} 
CheckError(AudioUnitRender(ioUnit, 
          &flags, 
          &inTimeStamp, 
          busNumber, 
          numberFrames, 
          bufferList), 
      "AudioUnitRender ioUnit"); 

Answer 1

两件事情，虽然没有看到更多的我不能说，如果这是所有这是错误的：

• 你的采样时间是无效的，你要增加这为绘制的每个循环。

• 您的AudioBuffer和AudioBufferList没有正确设置，调音台的输出数据格式通常会将频道拆分为单独的AudioBuffer而不是交错。无论哪种方式，你没有分配足够的空间，你应该是calloc ing，而你正在分配样本大小的对象，而不是字节大小的对象。

你AudioBufferList分配应该看起来更像这个（MixerHost年代后）：

AudioBufferList *ioData = (AudioBufferList *) malloc (
     sizeof (AudioBufferList) + sizeof (AudioBuffer) * (channelCount - 1) 
    ); 


    ioData->mNumberBuffers = channelCount; 

    int i; 
    for (i = 0; i < channelCount; i++) { 
     ioData->mBuffers[i] = {0}; 
     ioData->mBuffers[i].mNumberChannels = 1; 
     ioData->mBuffers[i].mDataByteSize = BUFFER_SIZE_IN_SAMPLES * 
      sizeof (AudioUnitSampleType); 
     ioData->mBuffers[i].mData = calloc(BUFFER_SIZE_IN_SAMPLES, 
      sizeof(AudioUnitSampleType); 
    }