Why is it that I can post the attached mp4 but not the source as a gif?
To make the mp4 I encoded the gif in handbrake, which actually made increased the file size but reduced the dimensions.
Source gif: 728*408, 785.5 KiB
Encoded mp4: 640*360, 836.7 KiB
On size, Lemmy uses pict-rs. There’s a per-instance-settable byte limit max on the max file size that can be uploaded to a pict-rs instance. I’ve got no idea whether it supports animated gifs.
EDIT: So, a bit of experimentation later, Pict-rs does take WebM. And WebM can contain AV1-encoded stuff, which can be lossless. But AV1 doesn’t appear to be optimized for GIF-style flat color images, the way MNG and APNG are. Still, you can get a (larger) file which a pict-rs instance will accept as long as it doesn’t hit the filesize limit, which represents the video in the GIF file without loss:
$ stat --format=%s ibjtdug-imgur.gif 804394 $ ffmpeg -i ibjtdug-imgur.gif -c:v libaom-av1 -aom-params lossless=1 ibjtdug-imgur-av1-lossless.webm $ stat --format=%s ibjtdug-imgur-av1-lossless.webm 1856545 $That slightly more than doubles the filesize.
That being said, I will point out that GIF itself really isn’t a great format for this. Like, the reason that many codecs won’t do well with this is because they deal poorly with dithered images. The original data (the original original data, pre-GIF-encoding) isn’t dithered, and got smashed down to 256 colors and an ordered dither when it was encoded as a GIF, and it’d probably be preferable to not dither it; using that would probably result in a better-quality and smaller video.
I’m on @jerry@infosec.exchange 's cursed Mbin instance, and I can upload GIFs as images. The upload filesize limit here is 6,000,000 bytes with the drawback that I can’t upload in better formats like MP4 or WebP.
I can increase that if you like.
based admin
5.71MB is plenty generous. I’d give up 5MB of that if we could have anonymous browsing again. I can’t recommend Mbin to people if they have to log in to see anything. Would converting all uploads to WebP lighten the load?
@hitstun connections to mbin are super heavy weight, which is fine if it were legit people browsing, but the AI scrapers endlessly hammering the site with hundreds or thousands of requests per minute ends up taking the whole site down. I’ll try opening it up again and see what happens and try to block as many crawlers as I can, but it’s been hundreds of net blocks in the past interspersed with other actual fediverse instances. Let’s see what happens.
I reenabled anonymous access and predictably the site started getting hammered immediately. I blocked a bunch of broad IP ranges that were the biggest sources but I’m sure I’ve probably blocked some legit people.
MP4 > GIF
I mean yeah but having to use handbrake to encode it is less than great.
I feel like something’s gone very wrong if the MP4 is dimensionally smaller but has a larger file size than the GIF
The original video was not dithered.
GIF is a format that was originally designed to do static images with flat colors. (Or, I think dithered…I know that PNG definitely can encode ordered dithers efficiently, and this is an ordered dither, rather than something like a Floyd-Steinberg dither).
GIF cannot do more than 256 colors in a frame, so whoever created the GIF will have, as part of the compression, caused the number of colors to be reduced, with dithering used to try to compensate for the lack of colors. That’s why it looks “grainy”.
Most video compression codecs are not optimized for compressing dithered images, because video normally doesn’t look like that.
If you took the original, pre-GIF-compression video, which wasn’t dithered down, and compressed it with something like MP4, you’d probably get rather better quality per byte size than you do with GIF. But once the video has been passed through GIF’s compression…shrugs
I’ve pretty much given up on Lemmy media uploads and I default to hotlinking these days.
Catbox.moe is a popular place for uploading for this purpose. Alternatively, I decided to roll my own for various reasons and you can DM me if you’re interested in testing the platform.
I’m pretty sure that pict-rs doesn’t force-convert things to WebP – the vanilla Lemmy Web UI just fails the upload, and I’m sure that it at least also does PNG and JPEG, as static images go. It might be that your client is doing a conversion to try to work around that limitation?
I only upload photos from the web interface. They all always become webp.
Hmm. I’m certain that they’ve just failed on lemmy.today’s vanilla Lemmy Web UI, not converted.
goes to test
I just created a test (non-animated) gif. Trying to upload it just fails — that is, one can select it and try to upload it, but the Web UI never inserts the uploaded image URL in the textbox.
Here it is on catbox.moe:
If I convert it to a PNG, a format that pict-rs does understand, it uploads without being converted to WebP:
Maybe it’s something unique to lemmy.blahaj.zone?
EDIT: There’s an option in the docker/docker-compose.yml in the lemmy git repo showing an example of how to add an option to force pict-rs to convert everything to WebP. So my bet is that lemmy.blahaj.zone has done that:
https://github.com/LemmyNet/lemmy/blob/main/docker/docker-compose.yml
# we can set options to pictrs like this, here we set max. image size and forced format for conversion # entrypoint: /sbin/tini -- /usr/local/bin/pict-rs -p /mnt -m 4 --image-format webpEDIT2: @Ada@lemmy.blahaj.zone would know.
We run our own custom image caching setup. I’ll ask Kaity to look in to it and see what’s going on
