Laser , 11 months ago

Thanks for the thorough answer.

<span style="color:#323232;">final: prev: lib.genAttrs (n: prev."${n}".overrideAttrs (old: {
</span><span style="color:#323232;">  buildInputs = old.buildInputs or [ ] ++ [ my-proprietary-codec ];
</span><span style="color:#323232;">})) packageNamesToModify
</span>

Thanks. I didn’t know that worked, however I’d say this is rather advanced nix. I know genAttrs “generate[s] an attribute set by mapping a function over a list of attribute names”, however for this piece of code I’d have trouble locating the list of attribute names. But I guess this is because I don’t understand overrideAttrs fully / correctly. In my defense, locating the documentation for that one isn’t trivial – I think this requires having some more experience with the language and the needed libraries. While I know that genAttrs is defined and explained in nixpkgs/lib/attrsets.nix, I’m not so sure about overrideAttrs– I’d guess it’s in nixpkgs/pkgs/stdenv/generic/make-derivation.nix? Even ryantm.github.io/nixpkgs/using/overrides/#sec-pkg… is not very verbose.

Please don’t take this as criticism, I know nix is a full language and I’m not trying to bash anyone here, however there’s quite the learning curve.

What you’re actually looking for here is a Gentoo USE-flags like system. We have a precursor of that in i.e. config.cudaSupport but it’s not widely used.

In my uneducated opinion, full use of USE-flags are rather complicated with package managers providing binaries, no? It would require a big number of builds for all possible options and their combinations.

You’d do that upstream because that’s something that every instance of ffmpeg should be able to do. And also ping me because I maintain ffmpeg ;)

Thanks for your work, I don’t really need jpeg-xl in ffmpeg, I played around with it when I was still using Arch (i.e. take screenshots in the format in mpv) but it wasn’t urgent enough for me to file an issue on Github.

I’d expect most packages to make use of such a feature dependently. I don’t know how gwenview or QT stuff works but from a quick Google I gather that KDE stuff has the kimageformats library which then in turn depends on jxl. Gwenview should depend on that but only depends on qtimageformats currently? I’d give adding kimageformats to its buildInputs a spin if you’re curious. If it works, make sure to submit a patch against Nixpkgs.

I had a quick glance at the definitions myself; also since 2021, kimageformats should provide support for jxl. My knowledge here was outdated that it needs a seperate plugin (Arch has one here aur.archlinux.org/…/qt5-jpegxl-image-plugin) but that seems to no longer be the case. Also I don’t actually have jxl files to test stuff with, since the major browsers don’t support it atm. I tried finding an easy example to OPs problem, though it seems it is kind of moot now, and Gwenview in nixpkgs does support JPEG-XL (just tested it by creating one via cjxl).