WebM (despite being closely related to WebP) can be 5-10x more efficient than WebP.
That's because WebP focused so strongly on being a GIF equivalent that it also dropped all things that made WebM efficient and instead adopted GIF's awfully inefficient architecture (just dumb frames overlaid on top of each other, without motion vectors or predicted frames).
Safari shows how it can be done: it supports silent MP4/H.264 straight in <img>. You get all the ease of use GIF, order of magnitude smaller file, and hardware acceleration.
It's unintuitive, but well-compressed videos are cheaper to decode than dumb "animation" formats, because file size differences are so massive that it's cheaper to decompress a small amount of complex data than to chew through vast amounts of poorly compressed data.
There's also the practical matter of network speed. In many common scenarios a 300kb webm can be fully downloaded and playing while a roughly equivalent 5mb gif is paused a few frames in, buffering.
I can't imagine any cheap SoC for smartphones without H.264 HW decoder because playing video is essential and it can record video. Possibly exists for low-feature phones without camera but it's not for web browsing.
The licenses for codecs sometimes cut into the thin margins on budget phones. A large amount of people outside of the US and EU are stuck on low-end phones, and I'm pretty sure many of the government subsidized phones in the US are in the same boat.
Edit- I was unaware the recently-announced Safari 14 Technical Preview adds support for WebP too! Making both formats viable for all browsers, finally.
Recently we've been going through the browser stats on our websites, and while globally apparently IE is dying, it's certainly not dead yet. In the specific industry I work in (Heavy Automotive Retailing, eg Truck Sales and Servicing), we see upwards of 30% of our users on browsers <= IE11. All of our sites are getting poor lighthouse scores on performance with the main suggestion to be changing to webp, but that would exclude 30% of our customers.
It only has VP8's intraframe compression, not VP8's interframe compression, so animated WebP is not a proper video codec and is a different beast to WebM video.
As far as I can tell though, it has to be VP8 and can't be VP9. Maybe I'm mistaken about that, but all the webp literature I've read or skimmed talks about VP8 specifically. So what's the advantage of an animated webp using VP8 over a webm using VP9?
I think this a very poor comparison to make because it denies the time dimension of video completely, which fundamentally affects how we perceive and use video, and also ignores the fact that still images linger and have different requirements.
For me is all about sharing. The website itself usually displays the "video" as if it was a gif, but as soon as you go to share anywhere, you're sharing a video on platforms that handle it like a video. No looping, seek controls, complicated UI, etc. I just want to post a photo that auto plays and loops anywhere. I don't are about the internals, but I want all applications to recognize that file as an animated photo, not a video.
video format usually take up too much memory: what you gain in efficiency costs in resources.
Conversely, animated WebP are dirt cheap: one buffer only, written over and over.
Then, there's optim being made in WebP to allow fast jump to keyframe, even when there's transparency. Video codec don't allow that, and you can have an arbitrary long torture sequence of transparent frame that needs to be decoded back when the video comes in the view again.
Last, animation are usually low-fps (~10fps): there, video codec don't perform very well and are basically keyframes. So the difference isn't as great as one would think.
Oh, and hardware need a 'reset' between decoding tasks, to reconfigure memory, and decoding can't be parallelized.
Eh. An animated image (an image that contains some sort of video media, whether gif or h264 or whatever) is a hint to the browser to play it automatically and without sound. If everything were true video (say, mp4) you couldn’t make that distinction. As long as the video in the animated video is encoded properly — as real video and not a sequence of frames as gif does — then animated images definitely have their places.
> An animated image (an image that contains some sort of video media, whether gif or h264 or whatever) is a hint to the browser to play it automatically and without sound. If everything were true video (say, mp4) you couldn’t make that distinction.
