I think I know where you're confused: from the guide it looks like there is only a difference where you put -ss; but in reality, where you put -t/-to matters to

I think I know where you're confused: from the guide it looks like there is only a difference where you put -ss; but in reality, where you put -t/-to matters too. In my Python script, I did input seeking for -ss (start point) part, and then output seeking for -t part (end point). As you can see, the -ss part is before -i {inputfile}, and -t is after. -ss 1:00 -i file -t 5 is NOT the same as -ss 1:00 -t 5 -i file. The latter has a bug that happens frequently when I'm trimming MPEG-TS files recorded from HDTV. It literally doesn't stop at the -t/-to timestamp for reason I don't know. And it only happens when stream copy. Below is a quick showcase: t.ts is the source, and the filenames show how I generate them with FFMPEG (for example, ss_t_i means input seeking -ss first, then -i t.ts, then -t 1:00). https://i.imgur.com/lLUSzEM.png https://i.imgur.com/lLUSzEM.png As you can see, if I use -t/-to before -i, it doesn't cut the file properly. >Also, input seeking should be inaccurate when doing stream copy Yeah, it's not frame accurate, can only cut at keyframes, but enough for my application. By the way the same inaccuracy exists for output seeking if you're doing stream copy.