I would like to have a simple free video editor that can cut and append files together without re-encoding. It's doable with avidemux, but it is just pain to manage.
Works well for the mp4 streams from my helmet camera, reliable key frames etc. For video that's been more highly compressed you'll need to compromise on the cut points if you want to avoid reencoding. And the cuts are abrupt, no fades or transitions.
The aged virtualdub does this as long as the container is avi (the codec could be avc/h.264 etc). I used avidemux to convert mp4 to avi without reencoding (just change the container format), then use virtualdub to trim it.
Actually I just write time stamps in a text file then use a groovy script to generate a script can be read by virtualdub, run virtualdub with the script to do the trimming.
It has worked for me for many years.
Not free but cheap.
https://en.wikipedia.org/wiki/Video_compression_picture_type...
If you need more resolution, you can apply more tricks, recompose i-frames from the same data, etc.