After searching and tinkering extensively, I am quite stumped if this is possible. My dilemma is this: I want to cut short scenes (ad breaks, ...) from a single movie file, but without reencoding the whole movie.

If I splice the movie up at I frames, and concat together again with stream copy, it works like a charm.

If I splice, then edit/reencode a part and concat together again - sometimes it works, sometimes there is broken audio - or even broken video for a few seconds. I can just imagine that reencoding the video part alters the beginning of that video part enough so that stream copy screws up.

Is there a way to tell ffmpeg "hey, reencode this 30 sec video with a filter (for fading and such) - but leave the first and/or last X seconds untouched"? Then stream copy should in theory work again.

Cheers,

Bernhard