ffmpeg: default to ffmpeg_4

[doronbehar]

Motivation for this change

Libraries without a version suffix should point to their latest version upstream! See https://discourse.nixos.org/t/nixpkgs-policy-regarding-libraries-available-in-multiple-versions/7026

This PR intends to make ffmpeg point to ffmpeg4. To make the review easier, I renamed the inputs where necessary for all derivations that used ffmpeg (without a version suffix) and as seen by the PR's labels, ofborg didn't detect any paths changed, besides of course ffmpeg itself.

Things done

• Tested using sandboxing (nix.useSandbox on NixOS, or option sandbox in nix.conf on non-NixOS linux)
• Built on platform(s)
  • NixOS
  • macOS
  • other Linux distributions
• Tested via one or more NixOS test(s) if existing and applicable for the change (look inside nixos/tests)
• Tested compilation of all pkgs that depend on this change using nix-shell -p nixpkgs-review --run "nixpkgs-review wip"
• Tested execution of all binary files (usually in ./result/bin/)
• Determined the impact on package closure size (by running nix path-info -S before and after)
• Ensured that relevant documentation is up to date
• Fits CONTRIBUTING.md.

[doronbehar]

@GrahamcOfBorg eval

[AluisioASG]

As far as I can tell, r128gain works with ffmpeg 4. Should we change it ourselves back when we update our packages?

[doronbehar]

As far as I can tell, r128gain works with ffmpeg 4. Should we change it ourselves back when we update our packages?

If you've meant that you should do that in a separate PR then yes, but I don't want to do include this change in this PR. The goal is to reduce the scope as much as possible as it's hard enough to get such a change in Nixpkgs (not to mention the amount of time it took me to s/ffmpeg/ffmpeg_3/g in all the files in a way that ofborg won't detect changes).

The general idea, is that when a package maintainer will come to edit their package expression, it will hopefully come to their attention that they use an old version of ffmpeg as an input.

[AluisioASG]

That's what I wanted to know, thank you.

[jonringer]

diff and package set difference LGTM

[1 built, 1 copied (1.1 MiB), 0.2 MiB DL]
https://github.com/NixOS/nixpkgs/pull/89264
1 package built:
ffmpeg

[jonringer]

this PR has been open for 12 days, which I think was ample time for people to voice any strong opposition to this

[doronbehar]

🎉 Thanks!