You have MP4 files with unwanted portions. You want to trim these portions.
- Download XMedia Recode.
- Under the Format tab set
Profile = Custom
Format = MP4
File Extension = mp4
- Click the Video tab and select Copy Mode.
- Click the Audio tab and select Copy Mode.
- Click the Filters/Preview tab and set Start Time and to (End Time).
- Click Add to queue button on the tool bar.
- Click Encode on the tool bar.