Fix loading nvEncodeAPI.dll in winarm64 build

Signed-off-by: nyanmisaka <nst799610810@gmail.com>

msys2/PKGBUILD/50-mingw-w64-ffnvcodec-headers/01-Load-nvEncodeAPI-dll-for-native-Windows-ARM64.patch

@@ -0,0 +1,34 @@
+From 15ee32753c92faddbabbff11676779618fc6db7e Mon Sep 17 00:00:00 2001
+From: Diego de Souza <ddesouza@nvidia.com>
+Date: Fri, 26 Jun 2026 22:59:03 +0200
+Subject: [PATCH] Load nvEncodeAPI.dll for native Windows ARM64
+
+On Windows on Arm, nvEncodeAPI.dll is an Arm64X dispatch proxy.
+It routes native ARM64 callers to nvEncodeAPIa64.dll and x64 or
+ARM64EC callers to nvEncodeAPI64.dll.
+
+Select the proxy for native ARM64 builds while preserving the existing
+library name for other 64-bit Windows targets.
+
+Signed-off-by: Diego de Souza <ddesouza@nvidia.com>
+---
+ include/ffnvcodec/dynlink_loader.h | 6 +++++-
+ 1 file changed, 5 insertions(+), 1 deletion(-)
+
+diff --git a/include/ffnvcodec/dynlink_loader.h b/include/ffnvcodec/dynlink_loader.h
+index 6d6a0ec..1be0dbf 100644
+--- a/include/ffnvcodec/dynlink_loader.h
++++ b/include/ffnvcodec/dynlink_loader.h
+@@ -50,7 +50,11 @@
+ # define CUDA_LIBNAME "nvcuda.dll"
+ # define NVCUVID_LIBNAME "nvcuvid.dll"
+ # if defined(_WIN64) || defined(__CYGWIN64__)
+-#  define NVENC_LIBNAME "nvEncodeAPI64.dll"
++#  if defined(_M_ARM64) || defined(__aarch64__)
++#   define NVENC_LIBNAME "nvEncodeAPI.dll"
++#  else
++#   define NVENC_LIBNAME "nvEncodeAPI64.dll"
++#  endif
+ # else
+ #  define NVENC_LIBNAME "nvEncodeAPI.dll"
+ # endif

msys2/PKGBUILD/50-mingw-w64-ffnvcodec-headers/PKGBUILD

@@ -12,8 +12,10 @@ url=https://github.com/FFmpeg/nv-codec-headers.git
 license=('spdx:MIT')
 makedepends=("git")
 _tag=451da99614412a7f9526ef301a5ee0c7a6f9ad76
-source=(git+https://github.com/FFmpeg/nv-codec-headers.git#tag=${_tag})
+source=("git+https://github.com/FFmpeg/nv-codec-headers.git#tag=${_tag}"
-sha256sums=('SKIP')
+        "01-Load-nvEncodeAPI-dll-for-native-Windows-ARM64.patch")
+sha256sums=('SKIP'
+            '43c248049c16e207635a9e56a26365b26014d2dc2d7c0e0688aa09ad649208f9')
 
 export MINGW_TOOLCHAIN_PREFIX="${MINGW_PREFIX}"
 export FF_MINGW_PREFIX="${MINGW_TOOLCHAIN_PREFIX}/ffbuild"
@@ -24,6 +26,12 @@ pkgver() {
   git describe --tags | sed 's/^n//'
 }
 
+prepare() {
+  cd nv-codec-headers
+
+  patch -p1 -i "${srcdir}/01-Load-nvEncodeAPI-dll-for-native-Windows-ARM64.patch"
+}
+
 build() {
   make PREFIX=${FF_MINGW_PREFIX} -C nv-codec-headers
   sed -n '4,25p' nv-codec-headers/include/ffnvcodec/nvEncodeAPI.h > LICENSE # Extract license