Okay, I'm on board. But what container am I meant to be using for my AV1 content? I see the value of a limited subset of mkv, e.g. webm, but webm is too lim

Okay, I'm on board. But what container am I meant to be using for my AV1 content? I see the value of a limited subset of mkv, e.g. webm, but webm is too limited in my opinion. It has no facilities for soft subtitles for instance. How is that an acceptable state of affairs? That's an accessibility issue. And yes, I know websites can send subtitles separately then render the subtitles over the <video> element, but that's no excuse for an ostensibly modern media container to not support subtitle tracks.