Add initial support for Windows ARM64

[anthony-linaro]

This PR adds support for building the plugin natively for Windows ARM64.

Had to switch buildspec to use my own fork, as the cmake in the main OBS tree blocks newer python. I suspect this is an oversight by OBS, as they have removed the limit elsewhere. For continuity, I would recommend pushing my changes to your own fork so that your code is not dependent on mine.

No CI as of yet, the scripts need a little bit of tweaking for the new GHA runners (lots of assumptions of Windows == x64).

Steps to test this is working:

1. Open an x64 VS tools window, and run an x64 configure from in there: cmake --preset windows-x64
2. Open an ARM64 VS tools window, and run an ARM64 configure from in there: cmake --preset windows-arm64
3. Build the plugin: cmake --build --preset windows-arm64
4. Install the plugin: cmake --install build_arm64 --prefix ./install --config RelWithDebInfo
5. Copy to obs plugins directory

[anthony-linaro]

Not entirely sure what's going on with macOS there, and I don't have a machine set up for it. It appears an empty list is being passed to add_dependencies somehow here: https://github.com/obsproject/obs-studio/blob/235be8ca3f8abcb99c4f44e9d9cea8ce9c736b99/cmake/macos/helpers.cmake#L89

[glikely]

I found the problem. Cmake option ENABLE_UI was renamed to ENABLE_FRONTEND in upstream obs-studio https://github.com/obsproject/obs-studio/commit/7db4a75913fb627c1d1c169dc51e5468ebb7a148, meaning that the frontend isn't getting disabled in the deps build. That seems to be fine on Windows and Linux, but it appears to break the macos build. I suspect macos is broken with ENABLE_FRONTEND=TRUE and ENABLE_PLUGINS=FALSE. Here is the fix:

diff --git a/cmake/common/buildspec_common.cmake b/cmake/common/buildspec_common.cmake
index e4a688b..b22504a 100644
--- a/cmake/common/buildspec_common.cmake
+++ b/cmake/common/buildspec_common.cmake
@@ -158,7 +158,7 @@ function(_setup_obs_studio)
     COMMAND
       "${CMAKE_COMMAND}" -S "${dependencies_dir}/${_obs_destination}" -B
       "${dependencies_dir}/${_obs_destination}/build_${arch}" -G ${_cmake_generator} "${_cmake_arch}"
-      -DOBS_CMAKE_VERSION:STRING=3.0.0 -DENABLE_PLUGINS:BOOL=OFF -DENABLE_UI:BOOL=OFF
+      -DOBS_CMAKE_VERSION:STRING=3.0.0 -DENABLE_PLUGINS:BOOL=OFF -DENABLE_FRONTEND:BOOL=OFF
       -DOBS_VERSION_OVERRIDE:STRING=${_obs_version} "-DCMAKE_PREFIX_PATH='${CMAKE_PREFIX_PATH}'" ${_is_fresh}
       ${_cmake_extra}
     RESULT_VARIABLE _process_result

[anthony-linaro]

I have reworked the commits and added your patch - hopefully the CI passes now!

[glikely]

Thanks Anthony. I’ll take a look at the changes tomorrow.

You can squash the ENABLE_FRONTEND patch into the dependencies update patch. If it is kept separate then the series won’t build cleanly when bisecting