No captions in YouTube livestreams

[peteruhrig]

Checklist

• I'm reporting a site feature request
• I've verified that I'm running youtube-dl version 2019.09.28
• I've searched the bugtracker for similar site feature requests including closed ones

Description

I'm not sure whether this is a bug report or a feature request, but there are no captions in livestreams, even though I can see them in the browser. Example:

 ~/ytdlvenv/bin/youtube-dl --write-sub --write-auto-sub --sub-lang en --write-info-json --sub-format vtt -f 'mp4[height=360]' -o "%(id)s.mp4" https://www.youtube.com/watch?v=rVH3vmpoOVA
[youtube] rVH3vmpoOVA: Downloading webpage
[youtube] rVH3vmpoOVA: Downloading video info webpage
[youtube] rVH3vmpoOVA: Downloading m3u8 information
WARNING: video doesn't have subtitles
[youtube] rVH3vmpoOVA: Looking for automatic captions
WARNING: Couldn't find automatic captions for rVH3vmpoOVA
[youtube] rVH3vmpoOVA: Downloading MPD manifest
[info] Writing video description metadata as JSON to: rVH3vmpoOVA.info.json
[download] rVH3vmpoOVA.mp4 has already been downloaded
[download] 100% of 1.36MiB

I am attaching the .info.json, which says the same thing:

"subtitles": {},
"automatic_captions": {},

rVH3vmpoOVA.info.json.txt

If I am missing something or doing it wrong, please let me know!

[peteruhrig]

It's not like I did not search for this with multiple keywords; I simply can't find anything. Could you point me to the relevant issue? Thanks!