Something

#!/bin/bash
inname=$1
outname=${inname%.avi}"_770.avi"

echo Encoding $inname to $outname
# This is without cropping and scaling - e.g. -vf-add crop=710:570 -vf-add scale=400x240

mencoder $inname -o $outname -srate 22050 -channels 2 -oac mp3lame -lameopts lowpassfreq=10000:mode=3:vbr=3:br=64 -af volnorm,channels=2 -ovc xvid -xvidencopts bitrate=236:vhq=4:lumi_mask:me_quality=6:vhq=4:lumi_mask:gmc -vf-add hqdn3d=09:0:10 2> /dev/null