iphone - 如何在Apple Aurio Touch( Audio Session 示例)应用程序中使输出静音？

Question

我已经根据苹果的aurio Touch编写了呼吸检测器
示例应用程序。但是我不知道如何设置音频单元或音频
session 不播放来自音频输入的声音。现在，当吹入麦克风时，
我可以从iPhone扬声器听到呼吸。如何预防呢？

这是苹果的音频 session 初始化代码:

            XThrowIfError(AudioSessionInitialize(NULL, NULL, rioInterruptionListener, self), "couldn't initialize audio session");
        XThrowIfError(AudioSessionSetActive(true), "couldn't set audio session active\n");


        UInt32 audioCategory = kAudioSessionCategory_RecordAudio;
        XThrowIfError(AudioSessionSetProperty(kAudioSessionProperty_AudioCategory, sizeof(audioCategory), &audioCategory), "couldn't set audio category");
        XThrowIfError(AudioSessionAddPropertyListener(kAudioSessionProperty_AudioRouteChange, propListener, self), "couldn't set property listener");

        Float32 preferredBufferSize = .005;
        XThrowIfError(AudioSessionSetProperty(kAudioSessionProperty_PreferredHardwareIOBufferDuration, sizeof(preferredBufferSize), &preferredBufferSize), "couldn't set i/o buffer duration");

        UInt32 size = sizeof(hwSampleRate);
        XThrowIfError(AudioSessionGetProperty(kAudioSessionProperty_CurrentHardwareSampleRate, &size, &hwSampleRate), "couldn't get hw sample rate");

        XThrowIfError(SetupRemoteIO(rioUnit, inputProc, thruFormat), "couldn't setup remote i/o unit");

        dcFilter = new DCRejectionFilter[thruFormat.NumberChannels()];

        UInt32 maxFPS;
        size = sizeof(maxFPS);
        XThrowIfError(AudioUnitGetProperty(rioUnit, kAudioUnitProperty_MaximumFramesPerSlice, kAudioUnitScope_Global, 0, &maxFPS, &size), "couldn't get the remote I/O unit's max frames per slice");

        fftBufferManager = new FFTBufferManager(maxFPS);
        l_fftData = new int32_t[maxFPS/2];



        XThrowIfError(AudioOutputUnitStart(rioUnit), "couldn't start remote i/o unit");

        size = sizeof(thruFormat);
        XThrowIfError(AudioUnitGetProperty(rioUnit, kAudioUnitProperty_StreamFormat, kAudioUnitScope_Output, 1, &thruFormat, &size), "couldn't get the remote I/O unit's output client format");

Answer 1

非常感谢Tim Bolstad
他的回答:
AURIOTouch使用单个回调将音频从输入传递到输出。所以最简单的事情是零
进行呼吸检测后，请清除ioData结构。

就像是:

for (UInt32 i=0; i < inData->mNumberBuffers; i++)
memset(inData->mBuffers[i].mData, 0, inData->mBuffers[i].mDataByteSize);

或者，您可以看一下CAPlayThrough示例，该示例具有用于输入和输出的单独回调。