AccessKit: Pause animated webp images

[Hrshl7]

Concept

Same as the Pause GIFs option, but applicable to animated webp.

[AprilSylph]

This shouldn't be a new option. If the "Pause GIFs" option doesn't work on uploaded WEBP, that's an oversight.

I'm not sure we have any methods available to determine if a WEBP is animated or not, though...

[marcustyphoon]

We don't have a way to determine if GIFs are animated, to be fair; we just assume they are :D I don't think there's a way that doesn't involve looking at the binary, and I can't remember if you can even do that in a web extension. Might only be doable if Tumblr staff specifically adds some sort of indicator in the code to animated images, which seems unlikely.

[AprilSylph]

Hmm... I wonder if we can just... apply the same assumption to WEBP. Why would anyone be uploading still images as WEBP? Tumblr certainly doesn't ever convert still images to WEBP.

Actually, do single-frame GIFs and WEBPs even stay as GIFs and WEBPs when uploaded?

[marcustyphoon]

I wonder if we can just... apply the same assumption to WEBP. Why would anyone be uploading still images as WEBP?

If they downloaded them from a site that transcodes, probably. My guess is that there are a quite small number of them now, but that might change in the future (yes, it sure seems like WebP lost the format wars, but you never know). Still might be good enough though. I do sometimes see us processing still GIFs. A version of this that applies to GIFs could also be a thing.

Then again, we could always just apply-to-all and revert that if or when that starts becoming a thing. You know, if this script, XKit Rewritten and Tumblr exist then. I think that seems like the most reasonable option.

Tumblr certainly doesn't ever convert still images to WEBP.

I wouldn't assume that to be true forever, backlash over image downloading aside. Again, though, can always just revert if it happens.

Actually, do single-frame GIFs and WEBPs even stay as GIFs and WEBPs when uploaded?

As alluded to, yes. I have seen single-frame GIFs in the wild, and I tested a WebP upload. (I didn't get around to digging up or creating all four variants and putting them into a test post to link here yet.)