#!/bin/bash

# start
date

# base variables
INPUT=$1
OUTPUT=$2
WIDTH=$(mplayer -identify "$INPUT" -ao null -vo null -frames 0 2>/dev/null | grep WIDTH | gawk -F = '{print $2}')
HEIGHT=$(mplayer -identify "$INPUT" -ao null -vo null -frames 0 2>/dev/null | grep HEIGHT | gawk -F = '{print $2}')

# set new size and margins
NEW_WIDTH=320
NEW_HEIGHT=$(($NEW_WIDTH*100/($WIDTH*100/$HEIGHT)))
TOP=$(((240-$NEW_HEIGHT)/2))
BOTTOM=$TOP

# all values must be a multiple of 2
NEW_WIDTH=$(($NEW_WIDTH+$NEW_WIDTH%2))
NEW_HEIGHT=$(($NEW_HEIGHT+$NEW_HEIGHT%2))
TOP=$(($TOP-$TOP%2))
BOTTOM=$(($BOTTOM+$BOTTOM%2))

# extract video
ffmpeg -i "$INPUT" -f mp4 -vcodec mpeg4 -r 25 -b 400 -padtop $TOP -padbottom $BOTTOM -s "$NEW_WIDTH"x"$NEW_HEIGHT" -aspect 4:3 -an temp.mp4
mp4creator -extract=1 temp.mp4 temp.divx
rm temp.mp4

# extract audio
ffmpeg -i "$INPUT" -ab 96 -ar 44100 temp.wav
faac -o temp.mp4 temp.wav
mp4creator -extract=1 temp.mp4 temp.aac
rm temp.wav temp.mp4

# mux audio/video
test -e "$OUTPUT" && rm "$OUTPUT"
mp4creator -H -i -I -c temp.divx -r 25 "$OUTPUT"
mp4creator -H -i -I -c temp.aac "$OUTPUT"
mp4creator -optimize "$OUTPUT"
rm temp.divx temp.aac

# finish
date