The text track setting saved to local storage and read by the MediaController during initialization are not taken into account by the TextController/TextTrack.

[HugoSaintLaurent]

Environment

• The MPD passes the DASH-IF Conformance Tool on https://conformance.dashif.org/
• The stream has correct Access-Control-Allow-Origin headers (CORS)
• There are no network errors such as 404s in the browser console when trying to play the stream
• The issue observed is not mentioned on https://github.com/Dash-Industry-Forum/dash.js/wiki/FAQ
• [] The issue occurs in the latest reference client on http://reference.dashif.org/dash.js/ and not just on my page

• Link to playable MPD file:
  https://storage.googleapis.com/shaka-demo-assets/sintel/dash.mpd

• Dash.js version: 4.5.2

• Browser name/version: Chrome Version 111.0.5563.147

• OS name/version: Windows 10

Steps to reproduce

Play a stream with multiple text tracks like https://storage.googleapis.com/shaka-demo-assets/sintel/dash.mpd for example.
Change to a different text tracks, leaving the video, retune, and verify if the text track matches the setting in the options menu.

Observed behavior

The text track setting are saved to local storage (https://github.sie.sony.com/SIE-Private/dashjs/blob/master/src/streaming/controllers/MediaController.js#L210).
And they are read by the MediaController during initialization (https://github.sie.sony.com/SIE-Private/dashjs/blob/master/src/streaming/controllers/MediaController.js#L69).
However, the TextController/TextTrack does not take into account these setting, and instead sets the default text track as the current one (https://github.sie.sony.com/SIE-Private/dashjs/blob/master/src/streaming/text/TextTracks.js#L161).

Turning off the closed captions is not remembered either. I'm not sure if this is expected or not.

This issue appears to be related to #1866

Console output

Sorry, I don't have log at the moment.

Expected behavior

After changing different text tracks, leaving the video, retuning, the text trackshould matches the setting in the options menu.

Possible solution

The following fix resolves the issue, however there might be a better way to fix this.

Modify https://github.sie.sony.com/SIE-Private/dashjs/blob/master/src/streaming/text/TextController.js#L128 as follow:
function createTracks(streamInfo) {
const streamId = streamInfo.id;

    if (!textTracks[streamId]) {
        return;
    }
    textTracks[streamId].createTracks();

    // Fix start
    // The Media Controller loads the initial text track saved in local storage,
    // but the Text Track doesn't.  Check to see if they're different and then
    // try and set the correct text track index.
    const textTrack = textTracks[streamId].getCurrentTrackInfo();
    const mediaTrack = mediaController.getCurrentTrackFor(textTrack.type, streamId);
    if (textTrack && mediaTrack && textTrack.index !== mediaTrack.index) {
        setTextTrack(streamId, mediaTrack.index - textTrack.index);
    }
    // Fix end

The unit tests have the same results with and without this change.

[dsilhavy]

@HugoSaintLaurent Can you please recheck in 4.7.0: https://reference.dashif.org/dash.js/v4.7.0/samples/dash-if-reference-player/index.html I was not able to reproduce the problem, reloading the media results in using the last selected track.

getCurrentTrack is called in _onTextTracksAdded

[dsilhavy]

Closing for now as this seems to work. Please comment if you see any remaining issues.

[HugoSaintLaurent]

Hi @dsilhavy, I finally had I chance to double check this issue. And it looks fixed on my end to with 4.7.0.
Best regards