Non-preloaded, default text track is loaded and parsed twice

[sethcarlton]

Description

When not preloading text tracks and setting a default, the default text track is being loaded and parsed twice, resulting in a "double caption"

Reduced test case: https://codepen.io/scarlton/pen/ZEpvaEo

Steps to reproduce

1. Set preloadTextTracks to false
2. Set one of your text tracks as default
3. Load the player

Results

Expected

A single network request for the default text track, the default track to be selected, the selected track cues to be shown.

Actual

Two network requests for the default text track, the default track is selected, the selected track cues are showing double.

Additional Information

On track load, if we are preloading OR this track is default, then loadTrack is called. However, when we are NOT preloading, loadTrack is also called for each track when its mode changes. Since a track set as default fires a mode change, loadTrack ends up being called twice.

As far as I can tell, the issue could be resolved by removing || default_ from line 344 of text-track.js. When preloading, all tracks would still be loaded here while non preloaded default tracks would load when its mode changes.

versions

videojs

7.10.2

browsers

Chrome (probably others)

OSes

macOS (probably Windows)

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[isabelleingato]

New here! I'd like to grab this one if that's okay.

I agree with the assessment of #6043 in the issue description. The other option would seem to be to assume the default track has always been preloaded and not try to load it a second time on mode change to "showing": https://github.com/videojs/video.js/blob/affc0611d978b1a6d02e443a46d14a58f2b1441c/src/js/tracks/text-track.js/#L240; that might be more aligned with the original intent of #2192.

[sethcarlton]

Yep that could also be a solution and may be more clear/more aligned with the original intent. Thanks for picking this up!