XVID fps, mp4box problem ?

[juGGaKNot]

Just noticed that the fps on my xvid encodes is wrong :

Frame rate mode : Variable
Frame rate : 59.994 fps
Minimum frame rate : 30.000 fps
Maximum frame rate : 60.000 fps
Original frame rate : 60.000 fps

AVS :

AVIsource("C:\x264\movie.avi")
ConvertToYV12(matrix="PC.601")
LoadPlugin("C:\x264\bin\autocrop.dll")
AutoCrop(0, 16, 16, threshold=0)

CMD :

-pass1 -progress 10 -threads 3 -overhead 0 -nopacked -vhqmode 4 -closed_gop -bvhq -framerate %myfps%
-pass2 -progress 10 -threads 3 -overhead 0 -nopacked -vhqmode 4 -closed_gop -bvhq -framerate %myfps% -avi %outxvid%

i get the %myfps% from

AVIsource("C:\x264\movie.avi",audio=false)
WriteFile("C:\x264\Movie_2D\T1\fps.txt", "Framerate")
ffmpeg -i "x.avs"
set /p myfps=<"%mypath%\%mpath%\T1\fps.txt"

And there is no problem this way for divx264 and x264.

I mux with mp4box

MP4box -add "movie.avi" -add "movie.m4a" -fps %myfps% -new "3.Movie_XVID_2D.avi"

What can cause this ? is it a problem ?

The raw avi is k, the muxed is not, shoud i use an other app ? (avi-gui ) for muxing ? i need a full cli app!

thnx.