[Bug] Auto-generated subtitles no longer display in the video player

[DUOLabs333]

Describe the bug
Even though a particular language is selected in the video player's "Caption Settings" menu, no captions are displayed. This is only an issue with auto-generated subtitles

Steps to Reproduce

1. Go to any video with auto-generated captions (eg, https://youtube.com/watch?v=l-nMKJ5J3Uc).
2. Go the the player's "Caption Settings"
3. Click on "english (auto-generated)"
4. Notice that there are no subtitles.

Logs

Screenshots

Additional context
Note that /api/v1/captions/l-nMKJ5J3Uc?label=English%20(auto-generated) returns

WEBVTT
Kind: captions
Language: en

[DUOLabs333]

I want to look into this --- does anyone know what URL Invidious uses to fetch the caption?

[syeopite]

It depends on whether the instance has the configuration option use_innertube_for_captions enabled.

The default endpoint Invidious uses is rate-limited on larger instances resulting in broken subtitles as Invidious is unable to fetch the captions from YouTube.

When the workaround use_innertube_for_captions is enabled though, Invidious utilizes YouTube's InnerTube transcript API as a workaround to generate captions. Said API is not ratelimited.

In this particular case, it seems like the bug is caused by your Invidious not enabling the workaround. If you try to view the auto generated caption on https://iv.nboeck.de (an instance with the workaround enabled) you'll see that the captions does show.

[DUOLabs333]

Interesting --- I'll try that. However, my instance isn't large --- I'm the only one that uses it, and I rarely watch more than 2-3 videos on it per day, which shouldn't be enough for a rate-limit.

[csmith1210]

I'm also experiencing this on my single user self-hosted instance. use_innertube_for_captions has fixed this, but should this now be enabled by default if the current default is no longer returning captions?

[DUOLabs333]

use_innertube_for_captions works for me too (I previously had it at the wrong level of indentation).

[syeopite]

I just did some testing.

It seems like YouTube changed something on the regular timedtext endpoint... manually-created captions still work but auto-generated captions are completely broken when not using the workaround.

Although, I'm not even sure if the auto-generated captions has ever actually worked in Invidious... There's been a feature request for YouTube's automatically translated captions for years now. See #2187 and automatically-generated untranslated captions probably also falls into that same category.

[LittleAmpton]

Auto-generated captions definitely worked at least a month ago because I've been using them regularly, and I never had the innertube option set.