option of subtitles provided by YouTube to be hardcoded into downloaded videos, similar to subbed anime

[RagglenLove]

Checklist

• I'm reporting a feature request
• I've verified that I'm running youtube-dl version 2020.01.24
• I've searched the bugtracker for similar feature requests including closed ones

Description

I'm requesting for the option of subtitles provided by YouTube to be hardcoded into downloaded videos, similar to subbed anime.

This is how I do it manually;

youtube-dl --write-sub https://www.youtube.com/watch?v=KaqC5FnvAEc

ffmpeg -i 'Trolling Saruman-KaqC5FnvAEc.en.vtt' 'Trolling Saruman-KaqC5FnvAEc.en.ass'

ffmpeg -i 'Trolling Saruman-KaqC5FnvAEc.mkv' -vf ass='Trolling Saruman-KaqC5FnvAEc.en.ass' 'Trolling Saruman-KaqC5FnvAEc-subbed.mkv'

And here is the output video: https://www.reddit.com/user/RagglenLove/comments/evxlkm/trolling_sarumankaqc5fnvaec_subbed/

Since youtube-dl relies on ffmpeg, I would like for this to be an available option, thanks.

[RagglenLove]

Hello, where is the duplicate issue please, because I couldn't find it earlier. Thanks.