Generating thumbnails/screenshots of a video is useful in many ways. Youtube and many other video sites use this to show a preview of the video as a small thumbnail. Google video captures a series of thumbnails from a video at various time intervals to show a better video preview.

There is a simple way to generate thumbnails in Linux using ffmpeg, a very very useful tool for processing videos. Let us generate a thumbnail for this video. Download the video and rename it to test.avi.

Then, run this command,

ffmpeg  -itsoffset -4  -i test.avi -vcodec mjpeg -vframes 1 -an -f rawvideo -s 320x240 test.jpg

This command generates a 320x240 sized PNG thumbnail at the 4th second in the video. The output looks like this.

If you do not have ffmpeg installed and are using Debian/Ubuntu, do,

sudo apt-get install ffmpeg

A series of thumbnails, at 4, 8, 12 and 16 seconds.

ffmpeg  -itsoffset -4  -i test.avi -vcodec mjpeg -vframes 1 -an -f rawvideo -s 320x240 test.jpg
ffmpeg  -itsoffset -8  -i test.avi -vcodec mjpeg -vframes 1 -an -f rawvideo -s 320x240 test.jpg
ffmpeg  -itsoffset -12  -i test.avi -vcodec mjpeg -vframes 1 -an -f rawvideo -s 320x240 test.jpg
ffmpeg  -itsoffset -16  -i test.avi -vcodec mjpeg -vframes 1 -an -f rawvideo -s 320x240 test.jpg

useful links

• Create a random thumbnail of a video file
• http://www.danielfischer.com/2007/06/27/how-to-use-ffmpeg-to-convert-video-via-ruby-on-rails/

Happy thumbnailing!