Enable videotoolbox on osx

[mmcauliffe]

Checklist

• [ ] Used a personal fork of the feedstock to propose changes
• [ ] Bumped the build number (if the version is unchanged)
• [ ] Reset the build number to 0 (if the version changed)
• [ ] Re-rendered with the latest conda-smithy (Use the phrase code>@<space/conda-forge-admin, please rerender in a comment in this PR for automated rerendering)
• [ ] Ensured the license file is being packaged.

This is needed for using ffmpeg as the backend for Qt Multimedia for Qt 6.7: https://github.com/conda-forge/qt-main-feedstock/pull/256.

Addresses #241, but mostly curious in figuring out whether videotoolbox can be re-enabled.

[conda-forge-webservices[bot]]

Hi! This is the friendly automated conda-forge-linting service.

I just wanted to let you know that I linted all conda-recipes in your PR (recipe) and found it was in an excellent condition.

[mmcauliffe]

So it's erroring with

libavcodec/videotoolbox.c:918:13: error: call to undeclared function 'VTRegisterProfessionalVideoWorkflowVideoDecoders'; ISO C99 and later do not support implicit function declarations [-Wimplicit-function-declaration]
            VTRegisterProfessionalVideoWorkflowVideoDecoders();

I'm not the most knowledgeable about Macs, but is this the result of the specific image that's being used for conda builds? It seems like it should be available on MacOSX 10.9+: https://developer.apple.com/documentation/videotoolbox/vtregisterprofessionalvideoworkflowvideodecoders().

[h-vetinari]

You can try setting

c_stdlib_version:   # [osx and x86_64]
  - "10.13"         # [osx and x86_64]

in recipe/conda_build_config.yaml, and add {{ stdlib("c") }} to the build requirements, and see if that fixes things. It's not a question of availability, but of not using K&R style declaration-less functions. In case the above doesn't help, you can also try

c_compiler_version:            # [osx]
  - 15                         # [osx]
cxx_compiler_version:          # [osx]
  - 15                         # [osx]

to get the last clang version that allowed this kind of thing by default.

[mmcauliffe]

@h-vetinari Perfect, thanks! This should be ready for review now!

[hmaarrfk]

I’m all for bumping the minimum OSX version.

So if that was the only change. I’m all for it.