Download YouTube-specific subtitle format called SRV3

Can you add support for downloading YouTube-specific subtitle format called SRV3 (also referred to as YTT for "YouTube Timed Text")?

There are plenty of these subtitles on YouTube in the karaoke section.

I found also 2 applications on github to convert to this format, from ass format and vice versa

YTSubConverter ytt2ass

Here's a couple of examples with subtitles like this: this and this.