音频数据（进入AvAudioEngine）在SwiftUi中播放嘶嘶作响的音频

Question

我正在尝试通过 GCDAsyncUdpSocket 将音频（通过 iPhone 麦克风）发送到另一个收听设备，我使用 AudioEngine 获取音频，并将 AVAudioPCMBuffer 转换为数据并通过套接字发送，但是当我收听即将到来的音频声音时，它会播放嘶嘶声，我下面分享了发送音频和将方法 AVAudioPCMBuffer 转换为数据，以及监听音频方法，为什么我从发送的音频中得到嘶嘶声？，谢谢..

//Sending Audio
    func sendAudio {
        audioEngine = AVAudioEngine()
        //var socket: GCDAsyncUdpSocket!
        let inputNode = audioEngine.inputNode
        var error: NSError?
        let bus = 0
        
        DispatchQueue.global(qos: .background).async { [weak self] in
            guard let self = self else { return }
            do {
                self.socket.setIPv4Enabled(true)
                self.socket.setIPv6Enabled(false)
                try self.socket.connect(toHost:"239.10.10.100" ?? "", onPort: 4545 ?? 0)
                try self.socket.beginReceiving()
                print("Socket started")
            } catch {
                print("Socket Started Error: \(error)")
            }
        }
         
        inputNode.installTap(onBus: bus, bufferSize: 2048, format: inputNode.inputFormat(forBus: bus)) {
            (buffer: AVAudioPCMBuffer!, time: AVAudioTime!) -> Void in
            
            DispatchQueue.global(qos: .background).async { [weak self] in
                guard let self = self else { return }
                do {
                    let data = self.toNSData(PCMBuffer: buffer)
                    print(data)
                    self.socket.send(data, withTimeout: 0, tag: 0)
                } catch {
                    print("Socket send Error: \(error)")
                }
            }
        }
        
        audioEngine.prepare()
        do {
            try audioEngine.start()
        } catch {
            print("Can't start the engine: \(error)")
        }
    }

func toNSData(PCMBuffer: AVAudioPCMBuffer) -> Data {
    let channelCount = 1  // given PCMBuffer channel count is 1
    let channels = UnsafeBufferPointer(start: PCMBuffer.floatChannelData, count: channelCount)
    let ch0Data = NSData(bytes: channels[0], length:Int(PCMBuffer.frameCapacity * PCMBuffer.format.streamDescription.pointee.mBytesPerFrame) / 2)
    return ch0Data as Data
}

// 收听音频

func udpSocket(_ sock: GCDAsyncUdpSocket, didReceive data: Data, fromAddress address: Data, withFilterContext filterContext: Any?) {
    audioPlayer.scheduleBuffer(getComingAudio(with: data), completionHandler: nil)
}

func getComingAudio(with data: Data) -> AVAudioPCMBuffer {
    let audioBuffer = AVAudioPCMBuffer(pcmFormat: audioFormat, frameCapacity: UInt32(data.count) / 2)!
    data.withUnsafeBytes { (bufferPointer: UnsafeRawBufferPointer) in
        let int16Array = Array(bufferPointer.bindMemory(to: Int16.self))
        let floatArray = int16Array.map { Float($0) / Float(Int16.max) }
        floatArray.withUnsafeBufferPointer { audioBuffer.floatChannelData!.pointee.assign(from: $0.baseAddress!, count: floatArray.count) }
    }
    audioBuffer.frameLength = audioBuffer.frameCapacity
    return audioBuffer
}

Answer 1

在发送端，您获取浮点数据：

let channels = UnsafeBufferPointer(start: PCMBuffer.floatChannelData, count: channelCount) 但是在接收端，你将其解释为 Int16 数据：

let int16Array = Array(bufferPointer.bindMemory(to: Int16.self)) 这至少是你问题的一部分。您还需要更广泛地确保两种格式相同。特别是具有不同的采样率并不罕见。但“静态”声音很可能是由于您的 float/int16 转换所致。

我会更简单地开始您的项目，并将数据写入内存，然后在同一设备上播放。这将确保您的基本逻辑有效。