swift – 尝试通过多路连接将音频从麦克风传输到另一部手机

我正试图通过Apples Multipeer Connectivity框架将音频从麦克风传输到另一部iPhone.要进行音频捕获和回放我正在使用AVAudioEngine(非常感谢 Rhythmic Fistman’s回答 here).

我通过在输入上安装一个麦克风从麦克风接收数据,从中我得到一个AVAudioPCMBuffer然后我转换为一个UInt8数组,然后我流到另一个手机.

但是当我将数组转换回AVAudioPCMBuffer时,我得到一个EXC_BAD_ACCESS异常,编译器指向我再次将字节数组转换为AVAudioPCMBuffer的方法.

这是我正在采取的转换和流输入的代码：

input.installTap(onBus: 0,bufferSize: 2048,format: input.inputFormat(forBus: 0),block: {
                (buffer: AVAudioPCMBuffer!,time: AVAudioTime!) -> Void in

                let audioBuffer = self.typetobinary(buffer)
                stream.write(audioBuffer,maxLength: audioBuffer.count)
            })

我的两个转换数据的功能(取自Martin.R的答案here)：

func binarytotype <T> (_ value: [UInt8],_: T.Type) -> T {
    return value.withUnsafeBufferPointer {
        UnsafeRawPointer($0.baseAddress!).load(as: T.self)
    }

}

func typetobinary<T>(_ value: T) -> [UInt8] {
    var data = [UInt8](repeating: 0,count: MemoryLayout<T>.size)
    data.withUnsafeMutableBufferPointer {
        UnsafeMutableRawPointer($0.baseAddress!).storeBytes(of: value,as: T.self)
    }
    return data
}

并在接收端：

func session(_ session: MCSession,didReceive stream: InputStream,withName streamName: String,fromPeer peerID: MCPeerID) {
    if streamName == "voice" {

        stream.schedule(in: RunLoop.current,forMode: .defaultRunLoopMode)
        stream.open()

        var bytes = [UInt8](repeating: 0,count: 8)
        stream.read(&bytes,maxLength: bytes.count)

        let audioBuffer = self.binarytotype(bytes,AVAudioPCMBuffer.self) //Here is where the app crashes

        do {
            try engine.start()

            audioPlayer.scheduleBuffer(audioBuffer,completionHandler: nil)
            audioPlayer.play()
       }catch let error {
            print(error.localizedDescription)

        }
    }
}

问题是我可以来回转换字节数组并在流式传输之前播放声音(在同一部手机中)但不在接收端创建AVAudioPCMBuffer.有谁知道为什么转换在接收端不起作用？这是正确的方法吗？

任何帮助,关于此的想法/意见将非常感激.

您的AVAudioPCMBuffer序列化/反序列化是错误的.

Swift3的演员阵容发生了很大的变化.似乎需要比Swift2更多的复制.

以下是如何在[UInt8]和AVAudioPCMBuffers之间进行转换的方法：

N.B：此代码假设单声道浮点数据为44.1kHz.
您可能想要更改它.

func copyAudioBufferBytes(_ audioBuffer: AVAudioPCMBuffer) -> [UInt8] {
    let srcLeft = audioBuffer.floatChannelData![0]
    let bytesPerFrame = audioBuffer.format.streamDescription.pointee.mBytesPerFrame
    let numBytes = Int(bytesPerFrame * audioBuffer.frameLength)

    // initialize bytes to 0 (how to avoid?)
    var audioByteArray = [UInt8](repeating: 0,count: numBytes)

    // copy data from buffer
    srcLeft.withMemoryRebound(to: UInt8.self,capacity: numBytes) { srcByteData in
        audioByteArray.withUnsafeMutableBufferPointer {
            $0.baseAddress!.initialize(from: srcByteData,count: numBytes)
        }
    }

    return audioByteArray
}

func bytesToAudioBuffer(_ buf: [UInt8]) -> AVAudioPCMBuffer {
    // format assumption! make this part of your protocol?
    let fmt = AVAudioFormat(commonFormat: .pcmFormatFloat32,sampleRate: 44100,channels: 1,interleaved: true)
    let frameLength = UInt32(buf.count) / fmt.streamDescription.pointee.mBytesPerFrame

    let audioBuffer = AVAudioPCMBuffer(pcmFormat: fmt,frameCapacity: frameLength)
    audioBuffer.frameLength = frameLength

    let dstLeft = audioBuffer.floatChannelData![0]
    // for stereo
    // let dstRight = audioBuffer.floatChannelData![1]

    buf.withUnsafeBufferPointer {
        let src = UnsafeRawPointer($0.baseAddress!).bindMemory(to: Float.self,capacity: Int(frameLength))
        dstLeft.initialize(from: src,count: Int(frameLength))
    }

    return audioBuffer
}