// Move everything from bytesOut into a new buffer.
    val fullBuffer = Buffer()
    bytesOut.read(fullBuffer, bytesOut.size)

    // Copy back all but what we're truncating.
    fullBuffer.read(bytesOut, lastFrame.start + length)
    outFrames.add(OutFrame(lastFrame.sequence, lastFrame.start, true))
    return writer
  }

  fun takeFrame(): InFrame = inFrames.take()

  fun play() {