I think you need to save the stream to the file system; then you can try using the MediaPlayer methodsetDataSource
FileInputStream rawmp3file= new FileInputStream(yourByteArrayAsMp3File);
mediaPlayer.setDataSource(rawmp3file.getFD());
If you can switch to a PCM sound source, check out the AudioTrack class.
AudioTrack Java . PCM . "" AudioTrack , (byte [], int, int) write (short [], int, int) .