code: func (h FrameHeader) IsValid() bool {
  	if len(h) < 4 {
  		return false
  	}
  	return h[0] == 0xff && h[1]&0xE0 == 0xE0 && h.Version() <= MPEG1 && h.Layer() <= Layer1
  }
docs: // IsValid tests the basic validity of the frame header by checking the sync word