如何实时获取音频录制缓冲区数据？

Question

我正在从 iPhone 麦克风获取音频数据并将其发送到套接字，我已经尝试使用 AVAudioEngine 来获取音频缓冲区，但有些它无法正常工作。所以你能建议我用什么更好的方法来实时记录缓冲区数据。

  override func viewDidLoad() {
        super.viewDidLoad()



        // initialize engine
        engine = AVAudioEngine()
        guard nil != engine?.inputNode else {
            // @TODO: error out
            return
        }



        SocketIOManager.sharedInstance.socket.on("listen") {data, ack in

            let BuffurData:Data = data[0] as! Data

            // let playData = self?.audioBufferToNSData(PCMBuffer: BuffurData as! AVAudioPCMBuffer)
            do {
               // let data = NSData(bytes: &BuffurData, length: BuffurData.count)

                let player = try AVAudioPlayer(data:BuffurData)
                player.play()
            } catch let error as NSError {
                print(error.description)
            }



            print("socket connected \(data)")
        }
    }

 func installTap() {

        engine = AVAudioEngine()
        guard let engine = engine, let input = engine.inputNode else {
            // @TODO: error out
            return
        }

        let format = input.inputFormat(forBus: 0)
        input.installTap(onBus: 0, bufferSize:4096, format:format, block: { [weak self] buffer, when in

            guard let this = self else {
                return
            }

            // writing to file: for testing purposes only
            do {
                try this.file!.write(from: buffer)
            } catch {

            }

            if let channel1Buffer = buffer.floatChannelData?[0] {
               let test = self?.copyAudioBufferBytes(buffer)
                let stram = self?.toNSData(PCMBuffer: buffer)
                SocketIOManager.sharedInstance.socket.emit("talk",stram!);

               // socket.on("listen", function (data)



                /*! @property floatChannelData
                 @abstract Access the buffer's float audio samples.
                 @discussion
                 floatChannelData returns pointers to the buffer's audio samples if the buffer's format is
                 32-bit float, or nil if it is another format.

                 The returned pointer is to format.channelCount pointers to float. Each of these pointers
                 is to "frameLength" valid samples, which are spaced by "stride" samples.

                 If format.interleaved is false (as with the standard deinterleaved float format), then
                 the pointers will be to separate chunks of memory. "stride" is 1.

                 If format.interleaved is true, then the pointers will refer into the same chunk of interleaved
                 samples, each offset by 1 frame. "stride" is the number of interleaved channels.
                 */

                // @TODO: send data, better to pass into separate queue for processing
            }            
        })

        engine.prepare()

        do {
            try engine.start()
        } catch {
            // @TODO: error out
        }
    }

Answer 1

试试这个代码：

var audioPlayerQueue = DispatchQueue(label: "audioPlayerQueue", qos: DispatchQoS.userInteractive)

var peerAudioPlayer: AVAudioPlayerNode = AVAudioPlayerNode()
var peerInputFormat: AVAudioFormat?

override func viewDidLoad() {
    super.viewDidLoad()
    // initialize engine
    engine = AVAudioEngine()
    guard nil != engine?.inputNode else {
        // @TODO: error out
        return
    }
    engine.attach(self.peerAudioPlayer)
    self.peerInputFormat = AVAudioFormat.init(commonFormat: .pcmFormatFloat32, sampleRate: 44100, channels: 1, interleaved: false)
    self.peerAudioEngine.connect(peerAudioPlayer, to: self.peerAudioEngine.mainMixerNode, format: peerInput?.outputFormat(forBus: 0))
    do {
        peerAudioEngine.prepare()
        try peerAudioEngine.start()
    } catch let error {
        print(error.localizedDescription)
    }

    SocketIOManager.sharedInstance.socket.on("listen") { data, ack in
        let pcmBuffer = toPCMBuffer(data: data)
        self.audioPlayerQueue.async {
            self.peerAudioPlayer.scheduleBuffer(pcmBuffer, completionHandler: nil)
            if self.peerAudioEngine.isRunning {
                self.peerAudioPlayer.play()
            } else {
                do {
                    try self.peerAudioEngine.start()
                } catch {
                    print(error.localizedDescription)
                }
            }
        }
    }

    print("socket connected \(data)")
}       

func toPCMBuffer(data: NSData) -> AVAudioPCMBuffer {
    let audioFormat = AVAudioFormat(commonFormat: AVAudioCommonFormat.pcmFormatFloat32, sampleRate: 44100, channels: 1, interleaved: false)  // given NSData audio format
    let PCMBuffer = AVAudioPCMBuffer(pcmFormat: audioFormat, frameCapacity: UInt32(data.length) / audioFormat.streamDescription.pointee.mBytesPerFrame)
    PCMBuffer.frameLength = PCMBuffer.frameCapacity
    let channels = UnsafeBufferPointer(start: PCMBuffer.floatChannelData, count: Int(PCMBuffer.format.channelCount))
    data.getBytes(UnsafeMutableRawPointer(channels[0]) , length: data.length)
    return PCMBuffer
}

func installTap() {    
    engine = AVAudioEngine()
    guard let engine = engine, let input = engine.inputNode else {
        // @TODO: error out
        return
    }

    let format = input.inputFormat(forBus: 0)
    input.installTap(onBus: 0, bufferSize: 4410, format: format, block: { (buffer: AVAudioPCMBuffer, AVAudioTime) in
        guard let this = self else {
            return
        }
        let stram = self?.toNSData(PCMBuffer: buffer)
        SocketIOManager.sharedInstance.socket.emit("talk",stram!)
    })

    do {    
        engine.prepare()
        try engine.start()
    } catch {
        // @TODO: error out
    }
}

// **Edit: For Enable Lound Speaker**

func speakerEnabled(_ enabled:Bool) -> Bool {
    let session = AVAudioSession.sharedInstance()
    var options = session.categoryOptions

    if (enabled) {
        options.insert(.defaultToSpeaker)
    } else {
        options.remove(.defaultToSpeaker)
    }

    try! session.setCategory(AVAudioSessionCategoryPlayAndRecord, with: options)
    return true
}