[jerich]

For the first question, I ended up using this trick for a video editing app on Android phones about 10 years ago in order to cut video together on low end, out of date (Android 2.3) phones. They couldn’t handle video compression in a reasonable time and we didn’t want to upload/download to process on a server.

The point of the app was to sync the cuts to music cues, so each clip had a defined length. I ended up doing it all through file manipulation. You can cut into a video file starting at any arbitrary I-frame then trim it to the desired length. I would cut the input videos down to size then concatenate the files, replacing the audio with the new soundtrack at the end.

It worked great, only took a few seconds to create the final edit. Of course you couldn’t overlay text or filter video, but I still think it was a valid solution.

With the requirement of starting each clip on an I-frame, there was some imprecision in where your cut would actually start—an arteur might have a problem with their masterpiece being butchered that way, but it would certainly work well for some special cases like efficient distribution or being able to show a diff that a video was unaltered outside of timing cuts.