使用AUAudioUnit录制音频时，禁用扬声器声音

Question

我尝试使用AUAudioUnit录制音频。我成功地获得了音频缓冲区，但在录音时也能通过扬声器听到录制的声音。问题是如何让缓冲区不把声音传给扬声器？

func startRecording() {
setupAudioSessionForRecording()
do {
let audioComponentDescription = AudioComponentDescription(
componentType: kAudioUnitType_Output,
componentSubType: kAudioUnitSubType_RemoteIO,
componentManufacturer: kAudioUnitManufacturer_Apple,
componentFlags: 0,
componentFlagsMask: 0 )
try auAudioUnit = AUAudioUnit(componentDescription: audioComponentDescription)
let audioFormat = AVAudioFormat(commonFormat: .pcmFormatInt16,
sampleRate: sampleRate,
interleaved: true,
channelLayout: AVAudioChannelLayout(layoutTag: kAudioChannelLayoutTag_Mono)!)
try auAudioUnit.inputBusses[0].setFormat(audioFormat)
try auAudioUnit.outputBusses[1].setFormat(audioFormat)
} catch {
print(error)
}
auAudioUnit.isInputEnabled  = true
auAudioUnit.outputProvider = {(actionFlags, timestamp, frameCount, inputBusNumber, inputData) -> AUAudioUnitStatus in
let err : OSStatus = self.auAudioUnit.renderBlock(actionFlags,
timestamp,
frameCount,
1,
inputData,
.none)
if err == noErr {
self.processMicrophoneBuffer(inputDataList:  inputData,
frameCount: UInt32(frameCount) )
} else {
print(err)
}
return err
}
do {
try auAudioUnit.allocateRenderResources()
try auAudioUnit.startHardware()
} catch {
print(error)
}
}

解决方案：

解决方案如下：https://gist.github.com/leonid-s-usov/dcd674b0a8baf96123cac6c4e08e3e0c

这个想法是在inputHandler内部调用呈现块，而不是在outputProvider中调用

auAudioUnit.inputHandler = { (actionFlags, timestamp, frameCount, inputBusNumber) in
var bufferList = AudioBufferList(mNumberBuffers: 1,
mBuffers: AudioBuffer(
mNumberChannels: audioFormat!.channelCount,
mDataByteSize: 0,
mData: nil))
let err: OSStatus = block(actionFlags,
timestamp,
frameCount,
inputBusNumber,
&bufferList,
.none)
if err == noErr {
self.processMicrophoneBuffer(inputDataList: inputData,
frameCount: UInt32(frameCount) )
} else {
print(err)
}
}

Answer 1

使RemoteIO输出静音的一种方法是在处理(复制(每个缓冲区后，将记录的输入数据中音频缓冲区的内容(frameCount样本(清零。