jellyfin-ffmpeg: use regular ffmpeg

NixOS#271863

jellyfin-ffmpeg is a rebuild anyways, so we can simply cherry-pick the features
that we actually need rather than smashing ffmpeg-full into it.

These should be all the "special" features jellyfin expects of it.

nvcodec and amf support are already enabled by default in regular ffmpeg.

pkgs/by-name/je/jellyfin-ffmpeg/package.nix

@@ -1,4 +1,4 @@
-{ ffmpeg_7-full
+{ ffmpeg_7-headless
 , fetchFromGitHub
 , fetchpatch
 , lib
@@ -8,14 +8,23 @@ let
   version = "7.0.2-5";
 in
 
-(ffmpeg_7-full.override {
+(ffmpeg_7-headless.override {
   inherit version; # Important! This sets the ABI.
   source = fetchFromGitHub {
     owner = "jellyfin";
     repo = "jellyfin-ffmpeg";
     rev = "v${version}";
     hash = "sha256-cqyXQNx65eLEumOoSCucNpAqShMhiPqzsKc/GjKKQOA=";
   };
+
+  # jellyfin-ffmpeg needs OpenCL or CUDA (depending on the GPU) for fully
+  # HW-accelerated video transcoding
+  # https://github.com/NixOS/nixpkgs/issues/271863#issuecomment-1837900239
+  withOpencl = true;
+  withCudaLLVM = true;
+
+  # This provides Intel Quicksync
+  withMfx = true;
 }).overrideAttrs (old: {
   pname = "jellyfin-ffmpeg";