AURenderCallbackStruct in Swift

问题

I have an Objective-C example to an AURenderCallbackStruct, and I would like to do one in swift. I read it's not possible, is that correct?

Thank you.

回答1:

It's possible. Use the following code for your Audio Unit settings.

init() {

    var status: OSStatus

    do {
        try AVAudioSession.sharedInstance().setPreferredIOBufferDuration(preferredIOBufferDuration)
    } catch let error as NSError {
        print(error)
    }


    var desc: AudioComponentDescription = AudioComponentDescription()
    desc.componentType = kAudioUnitType_Output
    desc.componentSubType = kAudioUnitSubType_VoiceProcessingIO
    desc.componentFlags = 0
    desc.componentFlagsMask = 0
    desc.componentManufacturer = kAudioUnitManufacturer_Apple

    let inputComponent: AudioComponent = AudioComponentFindNext(nil, &desc)

    status = AudioComponentInstanceNew(inputComponent, &audioUnit)
    checkStatus(status)

    var flag = UInt32(1)
    status = AudioUnitSetProperty(audioUnit, kAudioOutputUnitProperty_EnableIO, kAudioUnitScope_Input, kInputBus, &flag, UInt32(sizeof(UInt32)))
    checkStatus(status)

    status = AudioUnitSetProperty(audioUnit, kAudioOutputUnitProperty_EnableIO, kAudioUnitScope_Output, kOutputBus, &flag, UInt32(sizeof(UInt32)))
    checkStatus(status)

    var audioFormat: AudioStreamBasicDescription! = AudioStreamBasicDescription()
    audioFormat.mSampleRate = 8000
    audioFormat.mFormatID = kAudioFormatLinearPCM
    audioFormat.mFormatFlags = kAudioFormatFlagIsSignedInteger | kAudioFormatFlagIsPacked
    audioFormat.mFramesPerPacket = 1
    audioFormat.mChannelsPerFrame = 1
    audioFormat.mBitsPerChannel = 16
    audioFormat.mBytesPerPacket = 2
    audioFormat.mBytesPerFrame = 2

    status = AudioUnitSetProperty(audioUnit, kAudioUnitProperty_StreamFormat, kAudioUnitScope_Output, kInputBus, &audioFormat, UInt32(sizeof(UInt32)))
    checkStatus(status)


    try! AVAudioSession.sharedInstance().setCategory(AVAudioSessionCategoryPlayAndRecord)
    status = AudioUnitSetProperty(audioUnit, kAudioUnitProperty_StreamFormat, kAudioUnitScope_Input, kOutputBus, &audioFormat, UInt32(sizeof(UInt32)))
    checkStatus(status)


    // Set input/recording callback
    var inputCallbackStruct = AURenderCallbackStruct(inputProc: recordingCallback, inputProcRefCon: UnsafeMutablePointer(unsafeAddressOf(self)))
    AudioUnitSetProperty(audioUnit, AudioUnitPropertyID(kAudioOutputUnitProperty_SetInputCallback), AudioUnitScope(kAudioUnitScope_Global), 1, &inputCallbackStruct, UInt32(sizeof(AURenderCallbackStruct)))


    // Set output/renderar/playback callback
    var renderCallbackStruct = AURenderCallbackStruct(inputProc: playbackCallback, inputProcRefCon: UnsafeMutablePointer(unsafeAddressOf(self)))
    AudioUnitSetProperty(audioUnit, AudioUnitPropertyID(kAudioUnitProperty_SetRenderCallback), AudioUnitScope(kAudioUnitScope_Global), 0, &renderCallbackStruct, UInt32(sizeof(AURenderCallbackStruct)))


    flag = 0
    status = AudioUnitSetProperty(audioUnit, kAudioUnitProperty_ShouldAllocateBuffer, kAudioUnitScope_Output, kInputBus, &flag, UInt32(sizeof(UInt32)))
}

回答2:

You can format a callback function in Swift 4 like the following.

func recordingCallback(
  inRefCon:UnsafeMutableRawPointer,
  ioActionFlags:UnsafeMutablePointer<AudioUnitRenderActionFlags>,
  inTimeStamp:UnsafePointer<AudioTimeStamp>,
  inBusNumber:UInt32,
  inNumberFrames:UInt32,
  ioData:UnsafeMutablePointer<AudioBufferList>?) -> OSStatus {


  return noErr
}

Note this must be a global function and not inside of a class.

You can then set your callback function with the following code:

var callbackStruct = AURenderCallbackStruct()
callbackStruct.inputProc = recordingCallback
callbackStruct.inputProcRefCon = nil
status = AudioUnitSetProperty(remoteIOUnit!,
                                  kAudioOutputUnitProperty_SetInputCallback,
                                  kAudioUnitScope_Global,
                                  bus1,
                                  &callbackStruct,
                                  UInt32(MemoryLayout<AURenderCallbackStruct>.size));
if (status != noErr) {
  return status // Do something with the error
}

Source

来源：https://stackoverflow.com/questions/29942310/aurendercallbackstruct-in-swift

标签

swift

callback