avconv -i in.avi -vcodec mpeg4 -b 100000k out.avi
or in parallel:
find ./ -maxdepth 1 -name "*.avi" -type f | xargs -I@@ -P 8 -n 1 bash -c "filename=@@; avconv -i \$filename -vcodec mpeg4 -b 100000k \${filename/.avi/}-mpeg.avi"
11/18/13