As I was curious, I implemented it in javascript.
JsFiddle demo (edited image host as per comments).
What I found out:
- It works! And better than expected.
- The CPU usage is actually low (did not test it in IE6 dinosaur and I’m sure it would require “fixes”).
- The size can be cut off, and/or quality can be increased, significantly (source-dependent).
- Unlike Mikey G.’s concept, this works even if you zoom in/out (try it in both).
- It allows variable frame duration just like a gif.
- With more work, it could even have a player-like API (pause/resume, fastforward, skip, etc…).
- Leverages other formats: 8-bit alpha PNG, progressive JPEG,
<canvas>, SVG, WebP…
More info in the JsFiddle demo page.