Optional AVIF support

[Aloso]

This adds optional support for AVIF files. It can be enabled with --features=avif. Note that it requires cmake.

I can confirm that it works on Arch Linux. You can test if it works on your platform with this file: avif.zip

There's a tracking issue for AVIF support in image-rs, but that's unlikely to be implemented soon (image-rs only accepts pure Rust codecs).

If you don't think adding this is a good idea, feel free to close this PR.

[ArturKovacs]

Closing and re-opening to trigger a re-build.

[paolobarbolini]

I think you are missing Meson, Ninja and NASM.

• Ubuntu (please note we are using 20.04 to get the latest nasm Meson required by Dav1d)
• macOS
• I haven't written the Windows build but I think they are available via Chocolatey

[Aloso]

@paolobarbolini thanks for your help! I'll see if I get it to work on ubuntu and macos

[Aloso]

Note that I disabled the avif feature for Windows, since I don't know how to install the dependencies (mesa, ninja, nasm) on Windows.

[paolobarbolini]

I can make a PR to this repo when I get the chance to also add it to the libavif-rs CI

[ArturKovacs]

I can make a PR to this repo when I get the chance to also add it to the libavif-rs CI

@paolobarbolini I'm not sure what this means. Could you explain?

[paolobarbolini]

I can make a PR to this repo when I get the chance to also add it to the libavif-rs CI

@paolobarbolini I'm not sure what this means. Could you explain?

After writing the Windows CI steps for the libavif-rs repo I'll also open a PR for this one, since the CI configuration is very similar between the two repositories.

[paolobarbolini]

Update: I started working on the Windows support njaard/libavif-rs#15 but at the moment it's not working for some reason.

[ArturKovacs]

I love to hear that @paolobarbolini! Unfortunately I don't have much time for open source development but I can see that the relevant PR (njaard/libavif-rs#18) was merged so updating the libavif-rs dependency should be done for Emulsion but I'm not sure when will I get to it.

[paolobarbolini]

Windows support will come out in the v0.3 release. At the moment there aren't any breaking changes in the libavif-image crate, so you should be able to just bump the version once we release it. You can also try it right now by importing from git, but because of a bug in libgit2 cloning the repository might fail in some cargo versions.

Your CI isn't currently testing AVIF on Windows, and that will require the Windows job to be updated to install the libavif required build dependencies (build dependencies | tests), but that can be done later.