That's where I am now. I'd like to optimize out the retyping and duplication of time strings.

I want the player ui (I'm using mpv) to have a command that:

1. Remembers the last end time to use as this chapter's start time

2. Gets the current time to use as chapter-end.

3. Accepts the name (e.g. 'chapter1').

4. Runs the ffmpeg copy command.

Perhaps mpv+lua can already handle this. I see commands for setting a loop range and for calling a subprocess. Not sure how I'd input the chapter name. Maybe I'll have an LLM name the chapters for me :)