The length of video remains the same as original after splitting

[Moth Queen]

I have an original mp4 video that is 38:40. When I split it, the playable length is 23:48. The split video plays fine in mpc, but when I play it in VLC (my preferred media player) the length is shown as 38:40. So when I hit the seek bar towards the end, the video turns off because the playable length is 23:48 but, for some reason it is displayed as 38:40.

How do I fix this? I tried right-click and edit the details in the length box, but it wont let me.

BTW, I used boilsoft video splitter to split the video.

[Baldrick]

Boilsoft is crap as it does not update the mp4 headers correctly. But you could try repair the mp4 by remuxing it with yamb or mymp4boxgui, add the mp4 and create a new mp4.

Or try cut with avidemux.