VST does not appear in DAW when using libtorch

Audio Plugins
1

Hi, I am trying to build an VST3 plugin that loads a TorchScript model. I am using CMAKE to build the project. Right now I am just building the default AudioPluginExample project from the JUCE repository. I have added the following code to the CMakeLists.txt file:

find_package(Torch REQUIRED)
set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} ${TORCH_CXX_FLAGS}")
target_link_libraries(AudioPluginExample PRIVATE "${TORCH_LIBRARIES}")
set_property(TARGET AudioPluginExample PROPERTY CXX_STANDARD 14)

# The following code block is suggested to be used on Windows.
# According to https://github.com/pytorch/pytorch/issues/25457,
# the DLLs need to be copied to avoid memory errors.
if (MSVC)
  file(GLOB TORCH_DLLS "${TORCH_INSTALL_PREFIX}/lib/*.dll")
  add_custom_command(TARGET AudioPluginExample
                     POST_BUILD
                     COMMAND ${CMAKE_COMMAND} -E copy_if_different
                     ${TORCH_DLLS}
                     $<TARGET_FILE_DIR:AudioPluginExample>)
endif (MSVC)

The interesting thing is that I can load the project into a DAW (using Reaper) with no problems as long as I do not include the target_link_libraries(AudioPluginExample PRIVATE “${TORCH_LIBRARIES}”) line in CMakeLists.txt. As soon as I add that line, the plugin does not show up in the DAW any more. The build seems fine however, I do not get any errors while building the project. The commands I am using to build are:

cmake . -B cmake-build -DJUCE_BUILD_EXAMPLES=ON -DJUCE_BUILD_EXTRAS=ON -DCMAKE_PREFIX_PATH="D:\School\Grad School\Project\libtorch_debug\libtorch"
cmake --build cmake-build --target AudioPluginExample_VST3 --config Debug

Does anybody have any ideas as to what could be going wrong? Thanks!

2

Windows loads DLLs that are next to an executable when starting it, but that behavior doesn’t apply to plugins.

You have a few options:

  • build and link libtorch statically (so there is no DLL)
  • load the libtorch DLL at runtime (for instance using juce::DynamicLibrary)

Either way, please stop using ${TORCH_CXX_FLAGS} and ${TORCH_LIBRARIES}, that’s the old CMake way. find_package(Torch ...) provides an imported target torch that you can use directly to do target_link_libraries(AudioPluginExample PRIVATE torch).

1 Like
3

Is can share a full example of a JUCE plugin that works with Libtorch? I want know how convert torch::Tensor to JUCE and back.
Thanks you

4

Did you ever figure this out? I am able to build libtorch as a standalone application but trying to run it as a VST fails. Does anyone have example code or a guide for running JUCE with Libtorch in an audio plugin?