mencoder -> x264 : FPS problem : Video is 2x faster at the output

I got an input video, ffmpeg says about it : 29.96FPS 59.75 tbr 1k tbn 59.83 tbc My process to encode is :

$ mencoder input_video -vf dsize=480:320:0,scale=0:0,expand=480:320,dsize=1.5,format=i420 -of rawvideo -ofps 25 -ovc raw -nosound -o output.yuv
$ x264 input_video --profile baseline --fps 25 [blahblah] -o output
$ MP4Box -ad开发者_JS百科d output.yuv -fps 25 output.mp4

Im'simplificating a lot here to let you parse less as I'm encoding the audio apart and merging the result using mp4box.

ffmpeg -i output says that the vid is : 25 FPS 25 tbr 25 tbn 50 tbc

And while playing the video, the audio is normal, the video is 2x faster than input, so the video ends at the half of the audio track (compared to the input, the audio is good, it's just the video running 2x faster)

Any idea about my problem ?

I found the solution, just add -noskip to the mencoder line.