Since I’ve seen nothing which addresses the processing delays that I noticed in ffmpeg when generating thumbnail images, I figured I should share some important optimizations. I used to specify this command line when generating the images from a movie source (f4v in this case):
ffmpeg -y -i mymovie.f4v -an -ss 00:05:00 -t 00:00:00.01 -sameq -r 1 -vframes 1 -deinterlace -f mjpeg mythumbnail.jpg
This will take about one minute to generate the image of the video frame which is five seconds into the clip. This seems really extreme and is even worse when you try to increase the start location; for instance 45 seconds in, takes about an hour.
So, I knew there had to be a better way and I monkeyed around with the options:
ffmpeg -y -ss 00:05:00 -i mymovie.f4v -an -t 00:00:00.01 -sameq -r 1 -vframes 1 -deinterlace -f mjpeg mythumbnail.jpg
There is only one change between these lines, the placement of the “ss” option. This change causes the command to complete in less than a second, no matter what our start time is. Quite an increase in processing for something so simple! I hope this helps a few of you out there.