code: func (self AudioFrame) Slice(start int, end int) (out AudioFrame) {
  	if start > end {
  		panic(fmt.Sprintf("av: AudioFrame split failed start=%d end=%d invalid", start, end))
  	}
  	out = self
  	out.Data = append([][]byte(nil), out.Data...)
  	out.SampleCount = end - start
  	size := self.SampleFormat.BytesPerSample()
  	for i := range out.Data {
  		out.Data[i] = out.Data[i][start*size : end*size]
  	}
  	return
  }
docs: // Split sample audio sample from this frame.