缓冲区长度为frameCapacity * bytesPerframe。以下是可以在NSData和AVAudioPCMBuffer之间进行转换的函数。
func tonSData(PCMBuffer: AVAudioPCMBuffer) -> NSData { let channelCount = 1 // given PCMBuffer channel count is 1 var channels = UnsafeBufferPointer(start: PCMBuffer.floatChannelData, count: channelCount) var ch0Data = NSData(bytes: channels[0], length:Int(PCMBuffer.frameCapacity * PCMBuffer.format.streamDescription.memory.mBytesPerframe)) return ch0Data}func toPCMBuffer(data: NSData) -> AVAudioPCMBuffer { let audioFormat = AVAudioFormat(commonFormat: AVAudioCommonFormat.PCMFormatFloat32, sampleRate: 8000, channels: 1, interleaved: false) // given NSData audio format var 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}
