我有两个类,分别是MicrophoneHandler
和AudioPlayer
。我已经成功使用AVCaptureSession
来获取麦克风数据,方法在这里可以找到,并使用以下函数将CMSampleBuffer
转换为NSData
:
func sendDataToDelegate(buffer: CMSampleBuffer!)
{
let block = CMSampleBufferGetDataBuffer(buffer)
var length = 0
var data: UnsafeMutablePointer<Int8> = nil
var status = CMBlockBufferGetDataPointer(block!, 0, nil, &length, &data) // TODO: check for errors
let result = NSData(bytesNoCopy: data, length: length, freeWhenDone: false)
self.delegate.handleBuffer(result)
}
现在我想通过将上面生成的NSData
转换为AVAudioPCMBuffer
并使用AVAudioEngine
播放音频。我的AudioPlayer
类如下:
var engine: AVAudioEngine!
var playerNode: AVAudioPlayerNode!
var mixer: AVAudioMixerNode!
override init()
{
super.init()
self.setup()
self.start()
}
func handleBuffer(data: NSData)
{
let newBuffer = self.toPCMBuffer(data)
print(newBuffer)
self.playerNode.scheduleBuffer(newBuffer, completionHandler: nil)
}
func setup()
{
self.engine = AVAudioEngine()
self.playerNode = AVAudioPlayerNode()
self.engine.attachNode(self.playerNode)
self.mixer = engine.mainMixerNode
engine.connect(self.playerNode, to: self.mixer, format: self.mixer.outputFormatForBus(0))
}
func start()
{
do {
try self.engine.start()
}
catch {
print("error couldn't start engine")
}
self.playerNode.play()
}
func toPCMBuffer(data: NSData) -> AVAudioPCMBuffer
{
let audioFormat = AVAudioFormat(commonFormat: AVAudioCommonFormat.PCMFormatFloat32, sampleRate: 8000, channels: 2, interleaved: false) // given NSData audio format
let PCMBuffer = AVAudioPCMBuffer(PCMFormat: audioFormat, frameCapacity: UInt32(data.length) / audioFormat.streamDescription.memory.mBytesPerFrame)
PCMBuffer.frameLength = PCMBuffer.frameCapacity
let channels = UnsafeBufferPointer(start: PCMBuffer.floatChannelData, count: Int(PCMBuffer.format.channelCount))
data.getBytes(UnsafeMutablePointer<Void>(channels[0]) , length: data.length)
return PCMBuffer
}
当在上面的第一个代码片段中调用self.delegate.handleBuffer(result)
时,缓冲区会到达handleBuffer:buffer
函数。
我可以使用print(newBuffer)
查看转换后缓冲区的内存位置,但是没有任何声音从扬声器中输出。我只能想象在NSData
的转换过程中存在不一致的地方。有什么建议吗?先谢谢了。
NSData
是开箱即用的。你能把文件看作一个缓冲区吗?它恰好是一个磁盘缓冲区,但它仍然只是一个缓冲区。 - SwiftArchitect