Ringlets in the Encke Gap of Saturn’s rings. Photographed by Cassini, 14 December 2006.
Wait, 2006? Why wasn’t this gif posted a year or two ago?
In the olden days (before March 2014), Tumblr’s animated gif limits were an utterly confusing nightmare. Officially you were limited to 1MB filesize and some pixel limits, but there was obviously something more going on. With one exception, gifs longer than 99 frames would (for me) fail to upload. Sometimes I’d have to cut the frame number to below 50. It was horribly inconsistent.
The gif in today’s post is 154 frames long, and it, like so many other long gifs, failed to upload when I first made it. Then a few weeks ago I stumbled across a post from the Tumblr Engineering blog, saying that they’d fixed the gif irregularities!
The old problem had been caused by a couple of limits imposed by Tumblr: not only did the uploaded gif have to be below 1MB, but all resized gifs also had to be below 1MB. Furthermore, the resizes had to take less than 20 seconds.
The linked blog post doesn’t say if they used to use ImageMagick for these gif resizes, but it wouldn’t surprise me. It’s what I use, and a) it can be very slow to convert long gifs, especially with the -layers Optimize option, and b) it does some very strange things to file sizes sometimes (e.g., making the file bigger when you shrink it)
Tumblr worked with Gifsicle to get a tool which was fast, gave good results on resizing, and didn’t bizarrely increase file sizes. And so today we belatedly see these Encke Gap ringlets in gif form.
(I don’t have any other old long gifs waiting to be uploaded; all others I just truncated as much as necessary.)