[Retr0id]

I did something very similar with progressive (adam7 interlaced) PNG: https://www.da.vidbuchanan.co.uk/adamation/image.png

> so playback is entirely dependent on network delay

Ultimately true, but I set up my server to send each "frame" separately, with a fixed delay between each. Each frame is small so unless your network is unusually slow, the timing is set by my server.

[omoikane]

If you have control over the HTTP server, a different technique is to set "refresh" in the response header[1], which makes the client fetch new animation frames periodically. This is the technique used in a 2013 IOCCC entry to show a continuously updated clock that's rendered as PNG[2].

[1] https://developer.mozilla.org/en-US/docs/Web/HTTP/Reference/...

[2] https://www.ioccc.org/2013/mills/index.html

The "Refresh" header is encoded backwards on this line:

https://github.com/ioccc-src/winner/blob/619f554bbdb19e5003a...

[jbochi]

And I did something similar to steam live video via an infinite gif: https://github.com/jbochi/gifstreaming#live-video-streaming-...

[Dwedit]

Interesting that people are making hacks of PNG to do animations, yet there's also APNG sitting over there saying "Hey I exist!"

[donatj]

You don't even need a hack, there's built-in support for this.

https://en.wikipedia.org/wiki/Motion_JPEG

I've been here screaming "Motion JPEG EXISTS and is well supported in browsers" the entire time those gif hacks were popular. I've built a bunch of cool stuff with it.

https://github.com/donatj/mjpeg-php/blob/master/mjpeg.php

https://github.com/donatj/imgboard/blob/master/main.go

The PHP example here is an illustration of how easy it is to pull off, and the Go example is part of a JavaScript-free multiuser drawing board.

[Retr0id]

We even have proper video codecs like h264!

[account42]

Which can't be used in <img> tags which is the only method users have to embed media in many contexts.

[qingcharles]

Sure, but most sites strip the animation out of APNGs while still allowing GIFs, which is frustrating.

[moron4hire]

I did this once, 20 years ago, with an animated GIF to add a live streaming air quality layer to a map application at work. The image itself was rendered using Java2D. I had a version I was working on that used JOGL to make gradient blobs instead of point clouds, but I couldn't get the server admin to install the OpenGL driver to get it to work.