feat(flake): add hardware acceleration support for Linux in dev shell

Adds conditional dependencies for hardware acceleration on Linux including:
- Vulkan loader for Vulkan-accelerated encoders
- Intel media drivers for VA-API support
- oneVPL runtime for Intel QuickSync

Configures environment variables in shellHook to properly expose GPU drivers,
Vulkan loaders, and Intel media components when running on Linux systems.

Author: flexiondotorg

flake.nix

@@ -20,44 +20,75 @@
       in
       {
         devShells.default = pkgs.mkShell {
-          packages = with pkgs; [
-            # Build tools
-            autoconf
-            automake
-            libtool
-            cmake
-            curl
-            ffmpeg
-            file
-            gcc
-            git-filter-repo
-            gnumake
-            go
-            gperf
-            just
-            meson
-            nasm
-            ninja
-            # LLVM/Clang for code generator (go-clang requires libclang)
-            # llvmPackages.libclang provides: clang compiler + libclang library
-            # llvmPackages.llvm provides: llvm-config command
-            llvmPackages_18.libclang
-            llvmPackages_18.llvm
-            pkg-config
-            python3
-            yasm
-            # Rust toolchain for rav1e AV1 encoder
-            cargo
-            cargo-c
-            rustc
-          ];
+          packages =
+            with pkgs;
+            [
+              # Build tools
+              autoconf
+              automake
+              libtool
+              cmake
+              curl
+              ffmpeg
+              file
+              gcc
+              git-filter-repo
+              gnumake
+              go
+              gperf
+              just
+              meson
+              nasm
+              ninja
+              # LLVM/Clang for code generator (go-clang requires libclang)
+              # llvmPackages.libclang provides: clang compiler + libclang library
+              # llvmPackages.llvm provides: llvm-config command
+              llvmPackages_18.libclang
+              llvmPackages_18.llvm
+              pkg-config
+              python3
+              yasm
+              # Rust toolchain for rav1e AV1 encoder
+              cargo
+              cargo-c
+              rustc
+            ]
+            ++ pkgs.lib.optionals pkgs.stdenv.isLinux [
+              # Hardware acceleration runtime (Linux only)
+              vulkan-loader # Required for Vulkan accelerated encoders
+              intel-media-driver # VA-API driver for Intel GPUs (iHD_drv_video.so)
+              vpl-gpu-rt # oneVPL runtime for Intel GPUs (QSV backend)
+            ];
 
-          # Environment for go-clang CGO compilation
+          # Environment for go-clang CGO compilation and hardware acceleration
           shellHook = ''
             export CGO_LDFLAGS="-L${pkgs.llvmPackages.libclang.lib}/lib"
             export CPATH="${pkgs.llvmPackages.libclang.dev}/include"
             # Ensure vpx build finds yasm
             export PATH="${pkgs.yasm}/bin:${pkgs.nasm}/bin:$PATH"
+          ''
+          + pkgs.lib.optionalString pkgs.stdenv.isLinux ''
+            # Hardware acceleration: Make GPU drivers visible
+            # NixOS mounts GPU drivers under /run/opengl-driver/lib
+            if [ -d "/run/opengl-driver/lib" ]; then
+              if [ -z "$LD_LIBRARY_PATH" ]; then
+                export LD_LIBRARY_PATH="/run/opengl-driver/lib"
+              else
+                export LD_LIBRARY_PATH="/run/opengl-driver/lib:$LD_LIBRARY_PATH"
+              fi
+            fi
+            # Vulkan loader for h264_vulkan, hevc_vulkan, av1_vulkan encoders
+            export LD_LIBRARY_PATH="${pkgs.vulkan-loader}/lib:$LD_LIBRARY_PATH"
+            # Intel media driver and oneVPL runtime for QuickSync
+            export LD_LIBRARY_PATH="${pkgs.intel-media-driver}/lib:$LD_LIBRARY_PATH"
+            export LD_LIBRARY_PATH="${pkgs.vpl-gpu-rt}/lib:$LD_LIBRARY_PATH"
+            export ONEVPL_SEARCH_PATH="${pkgs.vpl-gpu-rt}/lib"
+
+            # Vulkan ICD discovery: tell vulkan-loader where to find GPU drivers
+            # NixOS installs ICDs under /run/opengl-driver/share/vulkan/icd.d/
+            if [ -d "/run/opengl-driver/share/vulkan/icd.d" ]; then
+              export VK_DRIVER_FILES=$(find /run/opengl-driver/share/vulkan/icd.d -name '*.json' 2>/dev/null | tr '\n' ':' | sed 's/:$//')
+            fi
           '';
         };
       }