#!/bin/sh

#
# Usage: ./fps.sh 20 24 new_
#        this is for input framerate 20, output framerate 24
#        prefix for new files "new_"
#
# NB no sanity checking is done!
#
# Ben Edgington 12/08/2002
#

ifps=$1
ofps=$2
dst_pfx=$3
src_pfx=''

echo "Converting from ${ifps}fps to ${ofps}fps"

interval=`expr $ifps / \( $ofps - $ifps \)`

# Start one before the first picture
src=0
dst=0

copy_src_dst ()
{
    echo "Copy $src_num to $dst_num"
    cp -f $src_num $dst_num
}

inc_src ()
{
    let src++
    src_num=`printf "${src_pfx}%8.8d.jpg" $src`
}

inc_dst ()
{
    let dst++
    dst_num=`printf "${dst_pfx}%8.8d.jpg" $dst`
}

inc_src
inc_dst

while [ -f $src_num ]
do

    copy_src_dst

    if !(($src%$interval))
    then
	inc_dst
	copy_src_dst
    fi

    inc_src
    inc_dst

done