Convert .ogv files to avi using mencoder

Convert .ogv to avi with sound

mencoder wgrass.ogv -ovc xvid -oac mp3lame -xvidencopts pass=1 -o wgrass.avi

Convert .ogv to .avi without audio

mencoder wgrass.ogv -ovc xvid -oac nosound -xvidencopts pass=1 -o wgrass.avi

Merge .mp4 files

mencoder -forceidx -ovc copy -oac pcm -o out.avi 1.mp4 2.mp4 3.mp4 4.mp4 5.mp4 6.mp4 7.mp4 8.mp4 9.mp4 10.mp4 11.mp4 12.mp4 13.mp4