Google Chromecast subtitle not working

Question

I have this code

var englishSubtitle = new chrome.cast.media.Track(2,chrome.cast.media.TrackType.TEXT);
englishSubtitle.trackContentId = 'english.vtt';
englishSubtitle.trackContentType = 'text/vtt';
englishSubtitle.subtype = chrome.cast.media.TextTrackType.CAPTIONS;
englishSubtitle.name = 'English';
englishSubtitle.language = 'en-US';
englishSubtitle.customData = null;
var tracks = englishSubtitle;

var mediaInfo = new chrome.cast.media.MediaInfo(app.streamState_.manifest);
mediaInfo.contentType = app.streamState_.type;
mediaInfo.metadata = new chrome.cast.media.GenericMediaMetadata();
mediaInfo.customData = null;
mediaInfo.streamType = chrome.cast.media.StreamType.BUFFERED;
mediaInfo.textTrackStyle = new chrome.cast.media.TextTrackStyle();
mediaInfo.tracks = tracks; 
mediaInfo.metadata.metadataType = chrome.cast.media.MetadataType.GENERIC;

var activeTrackIds = [2];   

var request = new chrome.cast.media.LoadRequest(mediaInfo);
request.autoplay = true;
request.currentTime = 0;
request.activeTrackIds = activeTrackIds;
session.loadMedia(request,onMediaDiscovered.bind(   this, 'loadedMedia'),  onMediaError);

I want to show subtitle on chromecast. When I want to set activeTracks on the request, I receive an error Object {code: "session_error", description: "INVALID_PARAMS", details: Object} The subtitle it doesn't show and the video doesn't play it at all, because of that error. Am I doing something wrong?

Answer 1

tracks should be an array when you set

mediaInfo.tracks = tracks;

In your case, you should try

var tracks = [englishSubtitle];

and as was said earlier, use SUBTITLES instead of CAPTIONS. Finally make sure you have CORS headers present from your web server even if you are using mp4.

Answer 2

tracks should be stored inside an array

https://developers.google.com/cast/docs/reference/chrome/chrome.cast.media.MediaInfo#tracks
Array of non-null chrome.cast.media.Track
Array of Track objects.

mediaInfo.tracks = [englishSubtitle, frenchSubtitle, germanSubtitle]

I've created a simple javascript wrapper for the chromecast SDK:
https://github.com/Fenny/ChromecastJS

Might be worth to check out if you stumble upon more problems, good luck!