为音频队列缓冲区获取 <AudioTimeStamp>

Question

我正在尝试在 Swift 中创建一个连续的 FIFO 录音机。我运行在尝试创建 audioQueueCallback 时遇到问题。

来自文档 AudioTimeStamp 有这个初始化方法：

AudioTimeStamp(mSampleTime: Float64, mHostTime: UInt64, mRateScalar: Float64, mWordClockTime: UInt64, mSMPTETime: SMPTETime, mFlags: AudioTimeStampFlags, mReserved: UInt32)

而且我不知道如何使用它。

在我看来，该设备应该有一个可靠的内部时钟，以便能够管理 audioQueues，但我还没有找到它的任何文档。

这是我创建 BufferQueue 的尝试：

ypealias WYNDRInputQueueCallback = ((Data) -> Void)

class WYNDRInputQueue {

  class WYNDRInputQueueUserData {
    let callback: WYNDRInputQueueCallback
    let bufferStub: NSData

    init(callback: @escaping WYNDRInputQueueCallback, bufferStub: NSData){
      self.callback = callback
      self.bufferStub = bufferStub
    }
  }


  private var audioQueueRef: AudioQueueRef?
  private let userData: WYNDRInputQueueUserData



  public init(asbd: inout AudioStreamBasicDescription, callback: @escaping WYNDRInputQueueCallback, buffersCount: UInt32 = 3, bufferSize: UInt32 = 9600) throws {

    self.userData = WYNDRInputQueueUserData(callback: callback, bufferStub: NSMutableData(length: Int(bufferSize))!)

    let userDataUnsafe = UnsafeMutableRawPointer(Unmanaged.passRetained(self.userData).toOpaque())

    let input = AudioQueueNewInput(&asbd,
                                   audioQueueInputCallback,
                                   userDataUnsafe,
                                   .none,
                                   .none,
                                   0,
                                   &audioQueueRef)

    if input != noErr {
      throw InputQueueError.genericError(input)
    }

    assert(audioQueueRef != nil )

    for _ in 0..<buffersCount {
      var bufferRef: AudioQueueBufferRef?

      let bufferInput = AudioQueueAllocateBuffer(audioQueueRef!, bufferSize, &bufferRef)

      if bufferInput != noErr {
        throw InputQueueError.genericError(bufferInput)
      }

      assert(bufferRef != nil)

这里是我使用 audioTimeStamp 的地方：

      audioQueueInputCallback(userDataUnsafe, audioQueueRef!, bufferRef!, <#T##UnsafePointer<AudioTimeStamp>#>, 0, nil)
    }
  }

  private let audioQueueInputCallback: AudioQueueInputCallback = { (inUserData, inAQ, inBuffer, inStartTime, inNumberPacketDescriptions, inPacketDescs) in

    let userData = Unmanaged<WYNDRInputQueueUserData>.fromOpaque(inUserData!).takeUnretainedValue()

    let dataSize = Int(inBuffer.pointee.mAudioDataByteSize)

    let inputData = Data(bytes: inBuffer.pointee.mAudioData, count: dataSize)

    userData.callback(inputData)

    AudioQueueEnqueueBuffer(inAQ, inBuffer, 0, nil)
  }

如有任何建议，我们将不胜感激！

Answer 1

我不确定时间戳将如何使用或谁将使用它，但如果有疑问，为什么不使用您记录的样本数作为时间戳？

var timestamp = AudioTimeStamp()

timestamp.mSampleTime = numberOfSamplesRecorded
timestamp.mFlags = .sampleHostTimeValid

为音频队列缓冲区获取 <AudioTimeStamp>

Obtain a <AudioTimeStamp> for Audio Queue Buffer

ios

swift

avfoundation

core-audio

audiotoolbox