Motivation:

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

Solution:

1. Download XMedia Recode.
2. Install the application.
3. Open a MP4 file.
4. Under the Format tab set
   Profile = Custom
   Format = MP4
   File Extension = mp4
5. Click the Video tab and set Mode = Copy on the middle panel.
6. Click the Audio tab and set Mode = Copy on the middle panel.
7. Click the Filters/Preview tab and set Start Time and to (End Time).
8. Click Add to queue button (with the + icon) on the tool bar.
9. Click Encode on the tool bar.

If you want to split a MP4 file to multiple files by time then just repeat the procedure except that in the 7th step, you specify appropriate time range for each file, for example from 00:00:00:0000 to 00:09:00:0000 for the first file, then from 00:09:00:0000 to 00:18:00:0000 for the second file, then from 00:18:00:0000 to 00:27:00:0000 for the third file, etc.