I wanted to convert some video files on my Linux system to the xvid codec so that I could see them on my PS3. The solution I found was using the mencoder package.
#!/bin/bash
# this script converts videos given to it to the xvid codec, IN PLACE,
# this means it replaces the original files...
for x in "$@"; do
echo "$x"
y="$x.tmp"
mencoder "$x" -ovc xvid -oac copy -xvidencopts fixed_quant=4 -o "$y"
ret=$?
if [[ $ret -eq 0 ]]; then
mv "$y" "$x"
ret=$?
if [[ $ret -ne 0 ]]; then
echo "problem moving file $x"
break
fi
else
echo "problem converting file $x"
break
fi
done