Motivation:

You have MP4 files with unwanted portions. You want to trim these portions.

Solution:

1. Download XMedia Recode.
2. Under the Format tab set
   Profile = Custom
   Format = MP4
   File Extension = mp4
3. Click the Video tab and select Copy Mode.
4. Click the Audio tab and select Copy Mode.
5. Click the Filters/Preview tab and set Start Time and to (End Time).
6. Click Add to queue button on the tool bar.
7. Click Encode on the tool bar.