As some of you may already know, Pixiv.net uses a custom format for animations — essentially a ZIP full of JPEGs.
Since it's not always easy transform these into a useful format, I've taken the liberty of writing a userscript which automatically converts Pixiv animations to animated-PNG files:

github.com/bipface/usersc...imation-converter.user.js

With the script running, every Pixiv animation should have a button underneath, {"Convert to APNG"}, like this: imgur.com/T1FbIJO
Click it and wait a minute; eventually it should offer you an animated-PNG (APNG) file containing the converted animation.

Near the top of the script I've also added some notes on converting APNG files to WebM, which is ideal for uploading them to Rule34. To do this, you'll need to use FFmpeg yourself though.

Let me know if you encounter any problems. I haven't tested it very thoroughly yet, but so far I've been really happy with the results.

Note that Chrome, IE, Opera and Edge don't have built-in support for animated PNGs. Firefox and Safari should work fine.

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Here's a few samples

source: www.pixiv.net/member_illu...um&illust_id=60761611
APNG: i.imgur.com/IbfAdi4.png
WebM: webmshare.com/WJrad

source: www.pixiv.net/member_illu...um&illust_id=60757004
APNG: imgur.com/n7BYpCR (50 megabytes!)
WebM: webmshare.com/wndLj

(NSFW:)
source: www.pixiv.net/member_illu...um&illust_id=50079941
APNG: imgur.com/t4KQO6T (60 megabytes!)
WebM: webmshare.com/KEJVB

Videos doesnt work.

which ones, the APNGs, the WebMs or the Pixiv sources? What browser are you using?

Apng's, chrome.

Ah, yes for some reason Chrome still doesn't support APNG. There's an extension for it though:
chrome.google.com/webstor...conegkhpodgoaeamnpckdbblp