Essentially there are two ways to make a time-lapse video, regardless of the tool. I chose FFmpeg because it was easy to use, and available on Ubuntu.

From Video

With the first, you take an existing video, recorded at 25 (or 30) frames per second, and strip out all the frames except for one every second. This gives you an effective speedup of 25x. For example, by extracting one frame per second from a 60 minute video, you can drop the length to a much more watchable, entertaining, and web-friendly 2.4 minutes (not to mention a smaller, easier to download file size).

Here’s a bash script (timelapsify.sh) that uses FFmpeg to convert a normal video into a time-lapse video. It takes an input video filename and an output video filename as command line arguments:

#!/bin/bash
# sample usage: ./timelapsify.sh input.avi output.mp4
mkdir ffmpeg_temp
ffmpeg -i $1 -r 1 -f image2 ffmpeg_temp/%05d.png
ffmpeg -i ffmpeg_temp/%05d.png -sameq $2
rm -rf ./ffmpeg_temp

From Stills

The other way is to set up your camera so that it takes a photo every 1 or 2 seconds. Many of the popular Canon Powershot cameras can be customized with a non-destructive, non-permanent firmware enhancement called CHDK which you can use to run a custom intervalometer (like this one). Or your camera may offer this functionality natively.

Keep in mind that 2 minutes of video represents 3000 distinct photos at 25 frames/second. Your battery or your memory card may run out before you get that far, so if possible, plug your camera in and set it to its lowest resolution setting.

One FFmpeg-specific caveat: in order to assemble photos into a video, you need to name them sequentially, starting from 1. So I wrote a simple little command line PHP script to rename the series of image filenames that my camera produced (IMG_3550.JPG, IMG_3551.JPG, IMG_3552.JPG) into something a little more FFmpeg-friendly (frame_1.jpg, frame_2.jpg, frame_3.jpg):

<?php
$files = scandir(".");
$i = 1;
foreach ($files as $file) {
  if (preg_match("/IMG_[0-9]{4}.JPG/", $file)) {
    copy($file, "frame_" . $i . ".jpg");
    $i++;
  }
}

And here’s the FFmpeg command to assemble all those renamed “frame” jpgs into an actual mp4, H.264-encoded video (very much like timelapsify.sh above):

ffmpeg -f image2 -r 25 -i frame_%d.jpg -vcodec libx264 -vpre hq -crf 22 video.mp4