Importantly, the webp format supports animation, and is considerably more efficient than animated gif. [1]
[1] http://res.cloudinary.com/demo/image/upload/fl_awebp/cell_an...
[1] http://res.cloudinary.com/demo/image/upload/fl_awebp/cell_an...
The concept of creating animated images out of the index frame format of a video codec is pretty amusing to me. Just use the video codec if you want video.
It's probably also an easier sell to the more problematic browsers (you know who they are) to support webp than webm.
> It's probably also an easier sell to the more problematic browsers
The only browser I can think of that does not support webm already but might conceivably add support for webp is Safari. Chrome, Firefox and Edge all support webm, and I don't see IE or Opera Mini adding webp support, since neither one is really in active development.
Maybe you're right that Safari is more likely to support webp than webm. It's hard to say.
http://www.html5rocks.com/en/tutorials/responsive/picture-el...
If a browser doesn't support that, it's probably not going to support the image format you're trying to negotiate anyway. In that case it's just going to fall back to the enclosed default img which is exactly what you'd want.