Adjacent advice:
I've recently played with opengl and jpeg turbo and I wanted to display images fast. I don't remember exact numbers, but enabling progressive for a jpeg was a significant slowdown for decoding.
So if anyone like me is stuck with the old school advice that progressive is an nice to have, it's likely not. I personally don't remember any visual progressive image buildup in like decades, so it's not doing anything valuable at all.
I wonder if and how you can use this for steganography, hiding data in plain sight. I bet most automated image analysis programs would only consider the final image. I sure some highschooler can use this to bypass their schools contentfilter
Nice! I think you can approximate timing somewhat, by making your web server create the "jpeg" on the fly and send it to the client in timed chunks. The source could even be a webcam, so the "jpeg" would go on forever.
The format supports progressive decoding but IIRC none of the current browser implementations support it. The first Chrome and Firefox implementations did, and I think it's on their roadmap for the new Rust implementation. No idea about WebKit/Safari.
Edit: the format also supports region-of-interest decoding and I suspect you can make some cool maps or fractal images with both features. But I think they're not quite prioritizing implementing that right now.
Excellent hack! Should definitely be possible to make an animated gif to jpeg converter. I guess the animation could be slowed a little by repeating frames.
That's basically the server telling the client 'That data I just sent you, well now replace it with this new thing'.
No JavaScript needed, and can work with plain http and jpeg
You can use Service Worker to emulate a slow connection :)
Edit: the format also supports region-of-interest decoding and I suspect you can make some cool maps or fractal images with both features. But I think they're not quite prioritizing implementing that right now.
But this is clever - just smash them together. Low frequency of one image concatenated with high frequency from another. This works surprisingly well!
Easy enough to add a delay() each frame if your server is python/nodejs/PHP/whatever