How does reverse seeking work?

[telekid]

Howdy! Thanks so much for making asciinema-player open source. I've enjoyed working with it recently.

I was curious as to how reverse seeking was implemented. After a cursory look at the code, it appears that you just feed each output between the playback head and the target location (or between the start of the recording and the target location in the case of reverse seeking) to the vt. Is that true? I would never have guessed that would be fast enough to scrub backwards from the end of the Star Wars recording. I guess this is a great example of "do the simple thing first."

[ku1ik]

Howdy!

Yeah, that's correct, it's done exactly like that. And it's the simplest thing I could do there.

I briefly touch on it in this post https://blog.asciinema.org/post/smaller-faster/

There's embedded player in that post, which is high bandwidth one, lots of color sequences etc, and it's equally fast to reverse-seek on it as on the Star Wars one. Rust/WASM is just super fast.

[telekid]

Awesome. Thanks for confirming!