我正在尝试通过Apples Multipeer Connectivity框架将音频从麦克风流式传输到另一部iPhone。为了进行音频捕获和回放，我使用了AVAudioEngine(非常感谢Rhythmic Fistman'的回答here)。
我通过在输入上安装一个抽头来从麦克风接收数据，由此我得到一个AVAudioPCMBuffer，然后将其转换为UInt8数组，然后将其流式传输到另一部电话。
但是，当我将数组转换回AVAudioPCMBuffer时，我得到了EXC_BAD_ACCESS异常，编译器指向了将字节数组再次转换为AVAudioPCMBuffer的方法。
这是我要处理，转换和流式处理输入内容的代码:
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)
})
我的两个函数都用于转换数据(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
}
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)
}
}
}
事实是，我可以在来回传输字节数组(在同一部电话中)之前来回转换字节数组并从中播放声音，但不能在接收端创建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，对此的想法/投入将不胜感激。
最佳答案
您的AVAudioPCMBuffer序列化/反序列化错误。
Swift3的转换方式已发生很大变化，并且似乎需要比Swift2更多的复制。
这是如何在[UInt8]和AVAudioPCMBuffer之间进行转换的方法:
N.B :此代码假定44.1kHz处的单声道浮点数据。
您可能要更改它。
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
}
关于swift - 尝试通过多点连接将音频从麦克风流传输到另一部电话，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/39505888/