mkv extract and mymp4box problems

[edy_smf]

i extract .264 movie from a mkv file with mkvextractGUI2 then mux it to mp4 with my mp4boxgui 0.5.5.4 but i have a problem after,even i keep 'NO CHANGE' option in the frame options the movie file has a shorter duration (from a 1.48.17 input a 1.44.11 duration output results)
when i merge back the video resulted and the original audio it is badly out of sync because ot time duration.
i made that 100 times before and it worked fine but sudenly i can't do it anymore ,can anyone tell me what happened,is some extraction problem in mkvextractgui or muxing problem?
the only thing i make in editor is just to increase resolution and dpi rate but it not changes the time duration or start/end points there.

[Baldrick]

Try a mkv to mp4 tool and see if you get same problem, https://www.videohelp.com/tools/sections/all-in-one-mkv-to-mp4-avchd-ts . Most are based on same software as you use.