opencv4 doesn't work with ffmpeg6 or ffmpeg7

[Lord-Kamina (Gregorio Litenstein)]

OpenCV4 has the following dependency path:lib/libavcodec.dylib:ffmpeg. This means if ffmpeg 6 or 7 are installed, it will insist on installing ffmpeg 4.4 and linking itself against that.

Symlinking the correct library from libexec/ffmpeg@version@/lib onto the main lib folder works fine, but is of course very cumbersome and unintuitive.

I'm not sure what the best way to to go around fixing this is. I'm thinking of two possibilities:

1) Variants. 2) Adding the folders inside libexec to the paths macports searches to satisfy this kind of dependencies.

I think conceptually, the ideal would be the latter but I'm not sure whether that's at all possible, and/or whether it could be done without adding uncertainty to builds in cases where more than one version of ffmpeg is installed at once, so maybe it'd be safer to go with variants.

Not sure what anyone else thinks about this?