@Override
    public MediaExtractor getAudioExtractor() throws IOException {
        if(mAudioFile != null) {
            // In case of a separate audio file, return an audio extractor
            MediaExtractor mediaExtractor = new MediaExtractor();
            mediaExtractor.setDataSource(mAudioFile.getAbsolutePath());
            return mediaExtractor;
        }
        // We do not need a separate audio extractor when only a single (multiplexed) file
        // is passed into this class.
        return null;
    }
Creates a media source from separate local video and audio files.
@param videoFile the video source file
@param audioFile the audio source file
MediaPlayer/src/main/java/net/protyposis/android/mediaplayer/FileSource.java