The number of pictures shown per second is known as “frames per second” (FPS) or Frame Rate. Pictures are flashed at a certain rate to trick the eye into thinking it’s seeing real motion. Since this concept comes from old film, it should be somewhat familiar. Video on the other hand, has a constant frame rate.

It’s one we used during development of GIFV. Bonus: This makes a handy calibration GIF since it can be estimated by a human easily.

The duration is 11 seconds though with delays of 2000, 3000, 1000, and 5000. The GIF below for example, is only 4 frames. A note here for those of you thinking of writing conversion software – pick a max cumulative duration so you don’t waste your time encoding a 50 day GIF. That delay can, according to spec, be anywhere from 0 to 4,294,967,295 milliseconds (thousandths of a second) on most computing platforms (that’s the limit for a 32 bit unsigned integer – almost 50 days). How does a GIF measure time? An animated GIF has a “delay” assigned to each frame – it’s essentially a slide show as originally intended. In order to encode video, you need to explode more than the original frames of a GIF – you need to get them to repeat at a constant rate. Tools such as ffmpeg don’t convert GIF delays to fill in dead space. If you want to convert GIFs to video or display a GIF frame by frame (thanks iOS!), you’ll run into a fundamental problem: GIFs don’t have a constant frame rate, but good video sources do.

Ffmpeg gif second per frame