The motivation for this started with some initial exploration of how native captions are inconcistent and extremely limited with respect to positioning + styling across browsers. In addtion, existing captions work was glued inside player libs and all open-source parsers were ancient (e.g., mozilla/vtt)!
I wanted to modernize it all with newer web APIs such as `fetch` and `ReadableStream` and extend support out to multiple captions formats. I also noticed that a lot of popular players on the web in recent years started adding caption customization options. Turns out accessible captions can be legally enforced!
Do note that accessible captions not only includes sync/timing, but also an adequate set of controls to customize the style of the captions, ensuring they're readable for everyone. You can see an example of this on YouTube when you go to the settings, captions, and click customize.
It just seemed silly that probably every single company is internally building this type of lib which is insanely hard to get right. I built this to serve our accessiblity goals at Vidstack[1] where we're working on enabling you to build a production-ready player quickly.
It took me about two weeks to build this and honestly there's still a lot of areas that need work but it's a great start. I hope you find it useful. You'll find a lot more helpful information in the repo.
I'll also leave you with this YouTube video where Dan Sparacio beautifully explains the complexities of building accessible media captions on the web at Paramount [2]. This is one of my favourite Demuxed talks. In there case, acessible enough to meet FCC guidelines. _Highly_ recommend checking it out to learn more!