I'm looking for a nice short easy way to create a series of thumbnails for any given video file. I'm almost there using ffmpeg, here's what I have:

ffmpeg -i /tmp/video.avi -r 1 -ss 60 -r 1 foo-%03d.jpeg`

The only problem is that this takes a shot every second and I'd like to make it every minute or so. I tried setting the -r value to 1/60 or .02 to no avail.

For reference, here's the old script I was using that only worked for some files:

#!/bin/bash
# grab a screenshot every 60 seconds
file=$1
orig_dir=`pwd`
mins=`exiftool "$file" | grep "Duration" | awk -F : '{print $2}' | grep --only-matching '[0-9]*'`
dir="$file-screenshots"
mkdir "$dir"
cd "$dir"
mplayer -vo png -vf screenshot -sstep 60 -frames $mins -ao null "../$file"
cd "$orig_dir"

This doesn't have to be on the command line, it's just that it always ends up being easiest.