[MEncoder-users] Why the duration becomes longer after converting?

[wisent]

Hi, all
 
I want to convert a m2ts format video to h264 format using mencoder.exe, but every time the duration of the converted video is about twice than the source file. The command line that I used is like:
 
mencoder.exe test.m2ts -o test.h264 -mc 0 -af volnorm,lavcresample=44100:channels=2 -vf scale=320:240,harddup -ofps 29.97 -ovc lavc -lavcopts vcodec=libx264 -oac copy -srate 44100
 
Why does this happen? Is there anything wrong with the command line? 
Any suggestions will be greatly appreciated.
Thanks!
 
 
-Wisent