A lot of advances and good ideas come when one browser or another pushes something beyond the World Wide Web Consortium (W3C) specs. This is one of those — MP4s in img tags.
The latest Safari Tech preview adds the ability to have MP4s in img tags. If this catches, on it means we can keep animations on the web efficient, but lose all the downsides of animated GIFs.
Animated GIFs: We’re Doing it Wrong
While animated GIFs can allow for some crude animation, it turns out the original GIF89a specification never really was meant for that.
The Graphics Interchange Format is not intended as a platform for animation, even though it can be done in a limited way.
If nothing else, this could be a great thing for bandwidth and quality. Since the GIF format is limited in its color pallette, and the fact that video codecs are constantly being evolved to allow for better compression, sites can have short animations and videos and still improve page load times.
MP4s in img tags
Another advantage of using the video in an image tag is you get the same benefits a static JPG, PNG, etc. get. They’ll preload, and early tests found in the article below say the speed is measurably faster—20x faster, while decode 7x faster than an equivalent .GIF.
It also would vastly improve responsiveness setups for video.
Read On More About MP4s in img tags
Read the article below for more of an in-depth look at the new feature, the big advantages, and a bunch of supporting comparisons and graphs of animated GIFs versus MP4s.
The biggest question is whether other web browsers will see this and embrace it. I’m not seeing any real downsides to this, other than the current state of browser support.
Source: Performance Calendar – Evolution of : Gif without the GIF