Avidemux converting mkv to mp4 1 second shorter fps different 23.976 24000/1001

[xomuz]

Hello
When I converting mkv movie to mp4 my movie is 1 second shorter and FPS is slightly different
form MediaInfo:
original: Frame rate : 23.976 FPS
after conversion: Frame rate : 23.976 (24000/1001) FPS
Why it can't copy 1:1?
In Video Output I have selected Copy option

[eumagga0x2a]

When I converting mkv movie to mp4 my movie is 1 second shorter and FPS is slightly different
form MediaInfo:
original: Frame rate : 23.976 FPS
after conversion: Frame rate : 23.976 (24000/1001) FPS
Why it can't copy 1:1?

MKV stores frame timestamps with a millisecond precision; the FrameRate field in the header is purely informational. MP4 uses a fraction (nominator/denominator) and thus an exact value.

[xomuz]

oh ok thanks for your reply