Trouble getting WebVTT captions/subtitles working on Chromecast

Question

I'm working on a Chromecast app for Android, and trying to get WebVTT captions/subtitles working.

I instantiate a MediaTrack object as follows:

            MediaTrack track = new MediaTrack.Builder(0, MediaTrack.TYPE_TEXT)
                .setContentId("http://www.example.com/example.vtt")
                .setSubtype(MediaTrack.SUBTYPE_SUBTITLES)
                .setContentType("ISO-8859-1")
                .setLanguage(Locale.ENGLISH)
                .setName("English")
                .build();

and add it to a list.

I instantiate MediaInfo using the builder, and include reference the list of tracks using the .setMediaTracks method:

MediaInfo.Builder builder = new MediaInfo.Builder("http://www.example.com/example.m3u8")
                .setStreamType(MediaInfo.STREAM_TYPE_BUFFERED)
                .setContentType("application/vnd.apple.mpegurl")
                .setMetadata(movieMetadata)
                .setMediaTracks(mediaTracks).build();

In my app I then start the CastControllerActivity that comes with the companion library:

mCastManager.startCastControllerActivity(this, mSelectedMedia, position, autoPlay);

After I've done this I set the active media track (only one in my case), and the text track style:

long [] activeTracks = new long[1];
activeTracks[0] = 0l;
mCastManager.getRemoteMediaPlayer()
        .setActiveMediaTracks(mCastManager.getGoogleApiClient(), activeTracks)
        .setResultCallback(new MediaResultCallback());
mCastManager.getRemoteMediaPlayer().setTextTrackStyle(
        mCastManager.getGoogleApiClient(),
        TextTrackStyle.fromSystemSettings(getBaseContext()));

When playing a clip containing subtitles the console shows the following:

[775.223s] [cast.receiver.MediaManager] Too many track IDs cast_receiver.js:18
[775.232s] [cast.receiver.MediaManager] Invalid track IDs cast_receiver.js:18
[775.238s] [cast.receiver.MediaManager] Sending error: INVALID_REQUEST INVALID_PARAMS

and the status code in the returned ResultCallback is SERVICE_MISSING - even though Google Play Services 5.0.89 is installed on both Android 4.4 devices I'm using when developing. The subtitles are hosted with CORS headers.

Any ideas or pointers?

Ali Naddaf Ali Naddaf · Accepted Answer · 2014-08-17T21:57:14

This is due to the fact that CCL has not yet been updated to handle Tracks (it is an upcoming feature). CCL builds a Bundle from MediaInfo and uses that bundle when firing the CastControllerActivity to pass the MediaInfo (MediaInfo is not parcelable, hence have to use a wrapper and a Bundle is one solution). In the exiting CCL, when it creates a bundle, it doesn't consider Tracks, hence the bundle doesn't have the tracks info. As a result, you are practically loading a media (since it happens in the CastControllerActivity) that doesn't have any tracks info, hence the error that you see.

Till Tracks support gets added to CCL, you can do the following. In Utils class, update the two methods fromMediaInfo() and toMediaInfo() with the following codes in the CCL itself:

private static final String KEY_TRACK_ID = "track-id";
private static final String KEY_TRACK_CONTENT_ID = "track-custom-id";
private static final String KEY_TRACK_NAME = "track-name";
private static final String KEY_TRACK_TYPE = "track-type";
private static final String KEY_TRACK_SUBTYPE = "track-subtype";
private static final String KEY_TRACK_LANGUAGE = "track-language";
private static final String KEY_TRACK_CUSTOM_DATA = "track-custom-data";
private static final String KEY_TRACKS_DATA = "track-data";

public static Bundle fromMediaInfo(MediaInfo info) {
    if (null == info) {
        return null;
    }

    MediaMetadata md = info.getMetadata();
    Bundle wrapper = new Bundle();
    wrapper.putString(MediaMetadata.KEY_TITLE, md.getString(MediaMetadata.KEY_TITLE));
    wrapper.putString(MediaMetadata.KEY_SUBTITLE, md.getString(MediaMetadata.KEY_SUBTITLE));
    wrapper.putString(KEY_URL, info.getContentId());
    wrapper.putString(MediaMetadata.KEY_STUDIO, md.getString(MediaMetadata.KEY_STUDIO));
    wrapper.putString(KEY_CONTENT_TYPE, info.getContentType());
    wrapper.putInt(KEY_STREAM_TYPE, info.getStreamType());
    if (!md.getImages().isEmpty()) {
        ArrayList<String> urls = new ArrayList<String>();
        for (WebImage img : md.getImages()) {
            urls.add(img.getUrl().toString());
        }
        wrapper.putStringArrayList(KEY_IMAGES, urls);
    }
    JSONObject customData = info.getCustomData();
    if (null != customData) {
        wrapper.putString(KEY_CUSTOM_DATA, customData.toString());
    }

    if (null != info.getMediaTracks() && !info.getMediaTracks().isEmpty()) {
        try {
            JSONArray jsonArray = new JSONArray();
            for (MediaTrack mt : info.getMediaTracks()) {
                JSONObject jsonObject = new JSONObject();
                jsonObject.put(KEY_TRACK_NAME, mt.getName());
                jsonObject.put(KEY_TRACK_CONTENT_ID, mt.getContentId());
                jsonObject.put(KEY_TRACK_ID, mt.getId());
                jsonObject.put(KEY_TRACK_LANGUAGE, mt.getLanguage());
                jsonObject.put(KEY_TRACK_TYPE, mt.getType());
                jsonObject.put(KEY_TRACK_SUBTYPE, mt.getSubtype());
                if (null != mt.getCustomData()) {
                    jsonObject.put(KEY_TRACK_CUSTOM_DATA, mt.getCustomData().toString());
                }
                jsonArray.put(jsonObject);
            }
            wrapper.putString(KEY_TRACKS_DATA, jsonArray.toString());
        } catch (JSONException e) {
            LOGE(TAG, "fromMediaInfo(): Failed to convert Tracks data to json", e);
        }
    }

    return wrapper;
}

public static MediaInfo toMediaInfo(Bundle wrapper) {
    if (null == wrapper) {
        return null;
    }

    MediaMetadata metaData = new MediaMetadata(MediaMetadata.MEDIA_TYPE_MOVIE);

    metaData.putString(MediaMetadata.KEY_SUBTITLE,
            wrapper.getString(MediaMetadata.KEY_SUBTITLE));
    metaData.putString(MediaMetadata.KEY_TITLE, wrapper.getString(MediaMetadata.KEY_TITLE));
    metaData.putString(MediaMetadata.KEY_STUDIO, wrapper.getString(MediaMetadata.KEY_STUDIO));
    ArrayList<String> images = wrapper.getStringArrayList(KEY_IMAGES);
    if (null != images && !images.isEmpty()) {
        for (String url : images) {
            Uri uri = Uri.parse(url);
            metaData.addImage(new WebImage(uri));
        }
    }
    String customDataStr = wrapper.getString(KEY_CUSTOM_DATA);
    JSONObject customData = null;
    if (!TextUtils.isEmpty(customDataStr)) {
        try {
            customData = new JSONObject(customDataStr);
        } catch (JSONException e) {
            LOGE(TAG, "Failed to deserialize the custom data string: custom data= "
                    + customDataStr, e);
        }
    }
    List<MediaTrack> mediaTracks = null;
    if (null != wrapper.getString(KEY_TRACKS_DATA)) {
        try {
            JSONArray jsonArray = new JSONArray(wrapper.getString(KEY_TRACKS_DATA));
            mediaTracks = new ArrayList<MediaTrack>();
            if (null != jsonArray && jsonArray.length() > 0) {
                for (int i = 0; i < jsonArray.length(); i++) {
                    JSONObject jsonObj = (JSONObject) jsonArray.get(i);
                    MediaTrack.Builder builder = new MediaTrack.Builder(
                            jsonObj.getLong(KEY_TRACK_ID), jsonObj.getInt(KEY_TRACK_TYPE));
                    if (jsonObj.has(KEY_TRACK_NAME)) {
                        builder.setName(jsonObj.getString(KEY_TRACK_NAME));
                    }
                    if (jsonObj.has(KEY_TRACK_SUBTYPE)) {
                        builder.setSubtype(jsonObj.getInt(KEY_TRACK_SUBTYPE));
                    }
                    if (jsonObj.has(KEY_TRACK_CONTENT_ID)) {
                        builder.setContentId(jsonObj.getString(KEY_TRACK_CONTENT_ID));
                    }
                    if (jsonObj.has(KEY_TRACK_LANGUAGE)) {
                        builder.setLanguage(jsonObj.getString(KEY_TRACK_LANGUAGE));
                    }
                    if (jsonObj.has(KEY_TRACKS_DATA)) {
                        builder.setCustomData(
                                new JSONObject(jsonObj.getString(KEY_TRACKS_DATA)));
                    }
                    mediaTracks.add(builder.build());
                }
            }
        } catch (JSONException e) {
            LOGE(TAG, "Failed to build media tracks from the wrapper bundle", e);
        }
    }
    return new MediaInfo.Builder(wrapper.getString(KEY_URL))
            .setStreamType(wrapper.getInt(KEY_STREAM_TYPE))
            .setContentType(wrapper.getString(KEY_CONTENT_TYPE))
            .setMetadata(metaData)
            .setCustomData(customData)
            .setMediaTracks(mediaTracks)
            .build();
}

This should hopefully solve your issue.

Trouble getting WebVTT captions/subtitles working on Chromecast

1 Answers