MediaPlayer getTrackInfo () never includes a TimedText

Question

MediaPlayer getTrackInfo () never includes a TimedText

I tried this sample iTech project (here you can find it here ) Its about displaying subtitles using the Android MediaPlayer class.

When I try to start a project, the media player works fine, but the subtitles do not. After debugging, I found out that getTrackInfo () returns an array with a length of 2 (this is only a video and audio track), and the timedText track was not included in the array. Does anyone know why?

For convenience, send the code snippet below:

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        txtDisplay = (TextView) findViewById(R.id.txtDisplay);
        MediaPlayer player = MediaPlayer.create(this, R.raw.video);

        try {
            player.addTimedTextSource(getSubtitleFile(R.raw.sub),
                    MediaPlayer.MEDIA_MIMETYPE_TEXT_SUBRIP);
            int textTrackIndex = findTrackIndexFor(
                    TrackInfo.MEDIA_TRACK_TYPE_TIMEDTEXT, player.getTrackInfo());
            Log.d(TAG, "textTrackIndex = "+textTrackIndex);
            if (textTrackIndex >= 0) {
                player.selectTrack(textTrackIndex);
            } else {
                Log.w(TAG, "Cannot find text track!");
            }
            player.setOnTimedTextListener(this);
            player.start();
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    private int findTrackIndexFor(int mediaTrackType, TrackInfo[] trackInfo) {
        int index = -1;
        Log.w(TAG, "trackinfo length = "+trackInfo.length);
        for (int i = 0; i < trackInfo.length; i++) {
            Log.d(TAG, "track type = "+trackInfo[i].getTrackType()+" and mediaTrackType = "+mediaTrackType);
            if (trackInfo[i].getTrackType() == mediaTrackType) {
                return i;
            }
        }
        return index;
    }

Please note: if you try a sample project, the video will not be displayed, but there will only be sound. This is not a mistake, as I think iTech intentionally does not show the video :)