MP4AudioInputStream(InputStream in, AudioFormat format, long length) throws IOException {
   super(in, format, length);
   mp4 = new MP4Reader(in);
   final DecoderConfig conf =
       DecoderConfig.parseMP4DecoderSpecificInfo(mp4.getDecoderSpecificInfo());
   decoder = new Decoder(conf);
   sampleBuffer = new SampleBuffer();
 }