# First pass
mencoder -v -v  -vf spp,scale video.vob \
    -ovc x264 \
    -x264encopts subq=1:partitions=all:8x8dct:me=umh:frameref=1:bframes=3:b_pyramid:weight_b:bitrate=2000
    -nosound \
    -of rawvideo \
    -ofps 23.976 \
    -o pass1.x264

NB:The error   happens it the first pass)
##########################################

# Second pass
mencoder -v myvideo.vob -ovc x264 -x264encopts subq=6:partitions=all:8x8dct:me=umh:frameref=5:bframes=3:bitrate=2000
    -nosound\
    -of rawvideo \
    -o pass2.x264