JPEG XL

ect optimized (with previews) ffmpeg png fpnge

for the anime images I kinda understand, given how fpnge works, but I do wonder what's up with the black images

can you try doing high effort fpnge?

it smells like there's a bug lurking

yeah, it happens even if it's a completely black or single-color frame hmm, I will try

`-5` is the maximum? looks like nothing changes

mhhhh interesting

ah, I think I know what's happening, I suspect we might end up not RLEing something like 15 values per row

an easy way to test this is to check whether a, say, 1024xY image and a 2048xY image, all black, have similar or different sizes

8x2048,8x1024

2048x8

mhhh ok

ah maybe I get it

IIRC fpnge forces lz77 symbols to have at least 8 bits

probably 10 or so

we might be observing that, probably for single color images this is a very suboptimal choice

I think I can make length-258 be its own symbol without issues and that should improve all black images a lot

libvips compression 1

*of course* the code seems to say I already do that

sigh... debugging time

ops, I am entirely blind, I misread your first set of images as being 1024x8

the behaviour on the second set makes sense and would be hard(er?) to fix

as for the first screenshot images... I see they are not entirely black, which certainly changes stuff

in particular they have super odd patterns

at least one does

looks like a DCT basis function that alternates between 0 and 1

that's pretty much the worst case for fpnge xD probably fixable by doing smarter LZ77, but I am unsure whether I want to try and figure that out

yes, probably because it's still a lossy video as the source, the colors may not be completely consistent

well, at least in most cases fpnge has the same or better compression than ffmpeg, and such images are a small percentage

I won't go to them asking to replace their png encoder, but if someone does I'm not opposed xD

for ffmpeg as already discussed there may be difficulties due to different licenses and if ffmpeg already has a stable internal encoder it will be hard to replace it because it must also consider stability, portability and simplicity besides better and faster compression and I have not compared other more typical images but for example for libvips for the fastest modes fpnge may be useful, plus the main developers are here, but this will also require more extensive benchmarks

yup, makes sense, as I said I don't particularly feel like trying to convince them

although I am pretty sure it is OK to use an Apache2 lib in a GPL program

and maybe it's worth it to add fpnge for djxl? having a fast transcoding to png in the jxl decoder would be cool and actual use would help improve or maybe fix some issues for fpnge