Encode frames saved in image files to 2-pass-mpeg4-compressed video

twopassenc.sh

#!/bin/sh
# optimal_bitrate = 50 * 25 * width * height / 256
# credits: http://personal.cscs.ch/~mvalle/mencoder/mencoder.html

if [ $1 = "-h" ] ; then
	echo "usage: twopassenc \"frames_run1/*.png\"   output1.avi   1920    1200"
	echo "                  [filname search string] [output file] [width] [height]"
else
	bitrate=`(echo  "50 * 25 * $3 * $4 / 256"|bc)`
	echo "Using bitrate: $bitrate"
	opt="vbitrate=$bitrate:mbd=2:keyint=132:v4mv:vqmin=3:lumi_mask=0.07:dark_mask=0.2:scplx_mask=0.1:tcplx_mask=0.1:naq"
	mencoder "mf://$1" -mf fps=25 -ovc lavc -lavcopts vcodec=mpeg4:vpass=1:$opt -nosound -o /dev/null
	mencoder "mf://$1" -mf fps=25 -ovc lavc -lavcopts vcodec=mpeg4:vpass=2:$opt -nosound -o $2
fi