Detect if a GIF is Animated
If you tweet an animated GIF, you'll notice that Twitter takes it and converts it to an mp4. I'd speculate that they do that conversion because an MP4 is better supported across platforms, at least in that they allow for playing/pause of the animation. And with a video you can prevent infinite looping, unlike a GIF. How can you determine if a GIF is animated though? I found a few good solutions.
Command Line with ImageMagick
ImageMagick, the amazing image manipulation library, provides a method for counting frames in a GIF:
./ImageMagick-6.9.0/bin/identify -format %n wtf.gif
The command above will provide you a count of the frames within the GIF.
animated-gif-detector
For those of you that prefer JavaScript (...my people...), I found a really simple animated GIF detection library on NPM: animated-gif-detector. Its API couldn't be shorter:
var fs = require('fs');
var animated = require('animated-gif-detector');
> animated(fs.readFileSync('wtf.gif'));
// true
> animated(fs.readFileSync('blank.gif'));
// false
The function call simply returns true or false, representing if the GIF is animated. Exactly what I wanted!
As for what each library looks for, I've seen some ugly bit code I wont try to describe. If you want to determine if a GIF is animated, however, it's as easy as the utilities above!
Only as a side note, Twitter is using mp4 because it’s an stream. Gif loading prevents the browser to fire the “ready” state until all of them are loaded. By using the video the event is fired meanwhile all the “gif” are being loaded in parallel.
And of course there is this webservice: https://doesthisgifcontainananimation.com/
Hey Robert: Any Idea on how to put that service to work? I can’t find the correct syntax to use with http://i.imgur.com/tYqyhJT.gif for example. If you have the solution, please let me know. Ok?
It’s easy! In Javascript, you can call:
encodeURIComponent("http://i.imgur.com/tYqyhJT.gif")Then you append the result to the domain, just like this:
https://doesthisgifcontainananimation.com/http%3A%2F%2Fi.imgur.com%2FtYqyhJT.gif
You can then see, whether the GIF contains an animation or not. :)
Oh, now I get it. I wasn’t understanding that encoding stuff. Thanks for clearing it out! :)
By the way: I’m now trying to get result to be fetched from a Javascript or Yahoo Pipe, but I’m not getting close. If you have or manage to find something, please bring some words once more O.K.?
Duhh!… Forget about it. Yahoo Pipes is shutting down, so…Nevermind.
Please, don’t advocate
fs.readFileSyncas it is not a good approach in 99% of the cases. animated-gif-detector supports streams, so use them instead. And you don’t even have to continue reading the file when you have already detected that it is a animated gif. Animated gifs can be big, and reading big files into memory is not too efficient, especially if they are not even on your local machine, but read from a network.