audiounit输入样品

Question

因此，我在iOS中的麦克风/线路中获取数据时在这里遇到了一些麻烦。我能够将所有内容设置为我认为还可以的一切，并且正在称呼我的录音，但是我从缓冲区中获得的数据不正确。它总是返回完全相同的东西，这主要是零和随机大数字。有人知道会导致这一点吗？我的代码如下。

设置音频单元

OSStatus status;

// Describe audio component
AudioComponentDescription desc;
desc.componentType = kAudioUnitType_Output;
desc.componentSubType = kAudioUnitSubType_RemoteIO;
desc.componentFlags = 0;
desc.componentFlagsMask = 0;
desc.componentManufacturer = kAudioUnitManufacturer_Apple;

// Get component
AudioComponent inputComponent = AudioComponentFindNext(NULL, &desc);
status = AudioComponentInstanceNew(inputComponent, &audioUnit);

// Enable IO for recording
UInt32 flag = 1;
status = AudioUnitSetProperty(audioUnit, 
                              kAudioOutputUnitProperty_EnableIO, 
                              kAudioUnitScope_Input, 
                              kInputBusNumber,
                              &flag, 
                              sizeof(flag));
// Disable playback IO
flag = 0;
status = AudioUnitSetProperty(audioUnit, 
                              kAudioOutputUnitProperty_EnableIO, 
                              kAudioUnitScope_Output, 
                              kOutputBusNumber,
                              &flag, 
                              sizeof(flag));

// Describe format
AudioStreamBasicDescription audioFormat;
audioFormat.mSampleRate         = 44100.00;
audioFormat.mFormatID           = kAudioFormatLinearPCM;
audioFormat.mFormatFlags        = kAudioFormatFlagsNativeFloatPacked |kAudioFormatFlagIsNonInterleaved;
audioFormat.mFramesPerPacket    = 1;
audioFormat.mChannelsPerFrame   = 1;
audioFormat.mBitsPerChannel     = 32;
audioFormat.mBytesPerPacket     = 4;
audioFormat.mBytesPerFrame      = 4;

// Apply format
status = AudioUnitSetProperty(audioUnit, 
                              kAudioUnitProperty_StreamFormat, 
                              kAudioUnitScope_Output, 
                              kInputBusNumber, 
                              &audioFormat, 
                              sizeof(audioFormat));

// Set input callback
AURenderCallbackStruct callbackStruct;
callbackStruct.inputProc = recordingCallback;
callbackStruct.inputProcRefCon = (__bridge void*)self;
status = AudioUnitSetProperty(audioUnit, 
                              kAudioOutputUnitProperty_SetInputCallback, 
                              kAudioUnitScope_Global, 
                              kInputBusNumber, 
                              &callbackStruct, 
                              sizeof(callbackStruct));
status = AudioUnitInitialize(audioUnit);

输入回调

static OSStatus recordingCallback(void *inRefCon, 
                                  AudioUnitRenderActionFlags *ioActionFlags, 
                                  const AudioTimeStamp *inTimeStamp, 
                                  UInt32 inBusNumber, 
                                  UInt32 inNumberFrames, 
                                  AudioBufferList *ioData) {

    AudioBufferList bufferList;
    bufferList.mNumberBuffers = 1;
    bufferList.mBuffers[0].mDataByteSize = 4;
    bufferList.mBuffers[0].mNumberChannels = 1;
    bufferList.mBuffers[0].mData = malloc(sizeof(float)*inNumberFrames); //
    InputAudio *input = (__bridge InputAudio*)inRefCon;

    OSStatus status;

    status = AudioUnitRender([input audioUnit], 
                             ioActionFlags, 
                             inTimeStamp, 
                             inBusNumber, 
                             inNumberFrames, 
                             &bufferList);

    float* result = (float*)&bufferList.mBuffers[0].mData;

    if (input->counter == 5) {
        for (int i = 0;i<inNumberFrames;i++) {
            printf("%f ",result[i]);
        }
    }
    input->counter++;
    return noErr;
}

任何人曾经遇到过类似的问题，或者在我的代码中看到明显的问题。预先感谢您的任何帮助！

我正在将所有内容基于

MichaelTysons Core Audio RemotioCode

Answer 1

如果我没记错的话，您从回调中的音频缓冲区中获得的样本不是浮点，它们是sint16。尝试施放这样的样品：

SInt16 *sn16AudioData= (SInt16 *)(bufferList.mBuffers[0].mData); 这些应该是最大和最小值：

#define sn16_MAX_SAMPLE_VALUE 32767
#define sn16_MIN_SAMPLE_VALUE -32768

Answer 2

AudioGraph()

。我遇到了同样的问题，麦克风的输出数据中的零，直到我添加行

直到我添加行才能正常工作。

Status = AUGraphConnectNodeInput(graph, ioNode, 1, ioNode, 0);

当您不使用图形时，您需要使用

AudioUnitSetProperty()

N来调用并通过并通过完整的AudioUnitConnection结构

改变

kAudioUnitProperty_MakeConnectio

Answer 3

to

float* result = (float*)&bufferList.mBuffers[0].mData; // the data from microphone is stored in mData. However, your ’result' actually points to the address of mData.