Any one Know what is the PASSTHROUGH_DECODER_INFO of both Himedia H8 & H8 plus  box

I am an android developer I am using Exoplayer for streaming of movies , But i am not able to utilize the passthrough option in exoplayer
If i use the normal video view it allows passthrough but we can't convert it to pcm if there is no external decoder for passthrough so no audio if it is a Ac3 codec
I s there any one successfully implemented passthrough in exoplayer in H8 box
https://github.com/google/ExoPlayer
does it have to do with this lines of code
  private static final MediaCodecInfo PASSTHROUGH_DECODER_INFO =
      MediaCodecInfo.newPassthroughInstance("OMX.google.raw.decoder");
Please help its urgent !!!!