1. Framewave
2. Guides
3. Cut without re-encoding

How to cut an MP4 without re-encoding

Re-encoding a video costs time and a little quality every time. A lossless trim copies the video's data as it is: an hour-long recording is cut in seconds, and not one pixel changes.

Cut losslessly

1. Open Framewave and drop your MP4 or MOV onto the page.
2. Set the start and end with the handles, or with I and O at the playhead.
3. Press Export and keep Automatic, or choose Lossless. Keep the format as MP4.
4. Press Export. The file is ready in seconds.

Why key frames matter

A compressed video stores a full picture only now and then (a key frame); the frames in between are stored as changes. Decoding has to start at a key frame, so a lossless copy also keeps the moment from the key frame before your start.

In MP4 and MOV that moment is hidden: players start right on your frame. Framewave shows it in amber on the timeline. In WebM and MKV it would play, so there Framewave re-encodes instead, unless your start is on a key frame (↑ and ↓ jump between them).