My use case is to cut segments from one video file and append the segments together. This way I can trim ads or parts I don't want.
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.
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.