ios - 麦克风播放的音频断断续续，听起来像是空气吹入麦克风

Question

我正在使用以下内容录制音频:

    localInput?.installTap(onBus: 0, bufferSize: 4096, format: localInputFormat) {
        (buffer, time) -> Void in

        let audioBuffer = self.audioBufferToBytes(audioBuffer: buffer)
        let output = self.outputStream!.write(audioBuffer, maxLength: Int(buffer.frameLength))

        if output > 0 {
            print("\(#file) > \(#function) > \(output) bytes written from queue \(self.currentQueueName())")
        }
        else if output == -1 {
            let error = self.outputStream!.streamError
            print("\(#file) > \(#function) > Error writing to stream: \(error?.localizedDescription)")
        }
    }

我的 localInputFormat 如下:

self.localInput = self.localAudioEngine.inputNode
self.localAudioEngine.attach(self.localAudioPlayer)
self.localInputFormat = self.localInput?.inputFormat(forBus: 0)
self.localAudioEngine.connect(self.localAudioPlayer, to: self.localAudioEngine.mainMixerNode, format: self.localInputFormat)

audioBufferToBytes函数如下:

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

    // initialize bytes by 0 
    var audioByteArray = [UInt8](repeating: 0, count: numBytes)

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

    return audioByteArray
}

在其他设备上，当我收到数据时，我必须将其转换回来。因此，当它收到时，它会执行以下操作:

func bytesToAudioBuffer(_ buf: [UInt8]) -> AVAudioPCMBuffer {

    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]

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

    return audioBuffer
}

最后，我们播放音频数据:

                self.audioPlayerQueue.async {
                    self.peerAudioPlayer.scheduleBuffer(audioBuffer)

                    if (!self.peerAudioPlayer.isPlaying && self.localAudioEngine.isRunning) {
                        self.peerAudioPlayer.play()
                    }
                }

但是，在任一扬声器上，我都只能听到有人每半秒敲击一次麦克风的声音。不是他们实际上在说话或什么。我想这是由于我从音频缓冲区到字节的转换造成的，但我不确定。有人发现上述内容有任何问题吗？

谢谢。

Answer 1

如果有人对解决方案感兴趣，基本上问题是录音设备上的音频是 17640 字节，但为了流式传输它，它会将其分解成更小的片段，而在接收设备上我必须读取第一个 17640 字节字节然后播放音频。不播放收到的每一小块数据。