如何使用 Swift 在 iOS 中同时录制和播放音频？

Posted 2023-02-15

【中文标题】如何使用 Swift 在 iOS 中同时录制和播放音频？

【英文标题】：How to record and play audio simultaneously in iOS using Swift?

【发布时间】：2016-08-26 09:55:54

【问题描述】：

在 Objective-C 中，同时录制和播放音频相当简单。互联网上有大量的示例代码。但我想在 Swift 中使用音频单元/核心音频同时录制和播放音频。使用 Swift 的帮助和示例代码很少。而且我找不到任何可以展示如何实现这一目标的帮助。

我正在为以下代码苦苦挣扎。

let preferredIOBufferDuration = 0.005 
let kInputBus  = AudioUnitElement(1)
let kOutputBus = AudioUnitElement(0)

init() 
    // This is my Audio Unit settings code.
    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! = AURenderCallbackStruct(inputProc: recordingCallback, inputProcRefCon: UnsafeMutablePointer(unsafeAddressOf(self)))
    inputCallbackStruct.inputProc = recordingCallback
    inputCallbackStruct.inputProcRefCon = UnsafeMutablePointer(unsafeAddressOf(self))
    status = AudioUnitSetProperty(audioUnit, kAudioOutputUnitProperty_SetInputCallback, kAudioUnitScope_Global, kInputBus, &inputCallbackStruct, UInt32(sizeof(UInt32)))
    checkStatus(status)


    // Set output/renderar/playback callback
    var renderCallbackStruct: AURenderCallbackStruct! = AURenderCallbackStruct(inputProc: playbackCallback, inputProcRefCon: UnsafeMutablePointer(unsafeAddressOf(self)))
    renderCallbackStruct.inputProc = playbackCallback
    renderCallbackStruct.inputProcRefCon = UnsafeMutablePointer(unsafeAddressOf(self))
    status = AudioUnitSetProperty(audioUnit, kAudioUnitProperty_SetRenderCallback, kAudioUnitScope_Global, kOutputBus, &renderCallbackStruct, UInt32(sizeof(UInt32)))
    checkStatus(status)


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



func recordingCallback(inRefCon: UnsafeMutablePointer<Void>,
                      ioActionFlags: UnsafeMutablePointer<AudioUnitRenderActionFlags>,
                      inTimeStamp: UnsafePointer<AudioTimeStamp>,
                      inBufNumber: UInt32,
                      inNumberFrames: UInt32,
                      ioData: UnsafeMutablePointer<AudioBufferList>) -> OSStatus 

    print("recordingCallback got fired  >>>")


    return noErr




func playbackCallback(inRefCon: UnsafeMutablePointer<Void>,
                      ioActionFlags: UnsafeMutablePointer<AudioUnitRenderActionFlags>,
                      inTimeStamp: UnsafePointer<AudioTimeStamp>,
                      inBufNumber: UInt32,
                      inNumberFrames: UInt32,
                      ioData: UnsafeMutablePointer<AudioBufferList>) -> OSStatus 

    print("playbackCallback got fired  <<<")


    return noErr

使用该代码，只有recordingCallback 方法被调用。并且 playbackCallback 方法根本没有被解雇。我确定我在这里出了点问题。有人可以帮我解决这个问题。我正在努力解决这个问题。

【问题讨论】：

audioUnit 变量在哪里？

【参考方案1】：

您错误地设置了InputCallback 和RenderCallback 方法。其他设置似乎还可以。所以你的init方法应该是这样的。

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)))

尝试使用此代码，如果有帮助，请告诉我们。

【讨论】：

如何使用此代码进行录音和像麦克风一样播放，同时它会在扬声器中播放

在哪里可以指定要从哪个设备进行录制？即 iPhone 与耳机？