The format exists, it's called ASS. It can do things like this: https://youtu.be/djrJP_Pi03U https://youtu.be/djrJP_Pi03U https://youtu.be/R3shsgKbd_M?t=12s h

The format exists, it's called ASS. It can do things like this: https://youtu.be/djrJP_Pi03U https://youtu.be/djrJP_Pi03U https://youtu.be/R3shsgKbd_M?t=12s https://youtu.be/R3shsgKbd_M?t=12s That's a pure text format; no bitmaps involved, just markup and TTF fonts. It can do vector shapes and perspective positioning. These are somewhat overdone examples, but one more common nice use case is literally translating signs on buildings, objects and such, seamlessly, while preserving the image style. The whole thing is rendered in real time and you can toggle the subs off and see the original frame. https://youtu.be/n_c-eKTisI0 https://youtu.be/n_c-eKTisI0 Again, that's all markup rendered on the video in real time from fonts. Yes, really. It is the standard in the anime fansub community, but has seen little adoption elsewhere. Partially this is because it seems commercial operations rarely have much interest in subtitle quality or technology. Incidentally, even YouTube supports an undocumented subtitle format that can support a decent amount of styling (YTT). Unfortunately, support is inconsistent across web/mobile versions, and it looks best when viewed in a browser. I've used it to do things like this (turn on captions): https://www.youtube.com/watch?v=dh1BCyjCbes https://www.youtube.com/watch?v=dh1BCyjCbes https://www.youtube.com/watch?v=IxLI7KmzOjE https://www.youtube.com/watch?v=IxLI7KmzOjE You can convert a subset of ASS to that format with this tool: https://github.com/arcusmaximus/YTSubConverter https://github.com/arcusmaximus/YTSubConverter