OK at this point I have no idea

Author: NicolasHug

src/torchcodec/_core/CMakeLists.txt

@@ -71,30 +71,11 @@ function(make_torchcodec_sublibrary
         )
     endif()
 
-    # For the core library, make dependencies PRIVATE to prevent transitive linking issues
-    # but still expose include directories
-    if(${library_name} MATCHES ".*_core[0-9]+$")
-        target_link_libraries(
-            ${library_name}
-            PRIVATE
-            ${library_dependencies}
-        )
-        # Manually expose FFmpeg include directories as PUBLIC for compilation
-        foreach(dep ${library_dependencies})
-            if(TARGET ${dep})
-                get_target_property(dep_include_dirs ${dep} INTERFACE_INCLUDE_DIRECTORIES)
-                if(dep_include_dirs)
-                    target_include_directories(${library_name} PUBLIC ${dep_include_dirs})
-                endif()
-            endif()
-        endforeach()
-    else()
-        target_link_libraries(
-            ${library_name}
-            PUBLIC
-            ${library_dependencies}
-        )
-    endif()
+    target_link_libraries(
+        ${library_name}
+        PUBLIC
+        ${library_dependencies}
+    )
 
 endfunction()
 
@@ -160,19 +141,32 @@ function(make_torchcodec_libraries
         AVIOTensorContext.cpp
         custom_ops.cpp
     )
-    set(custom_ops_dependencies
-        ${core_library_name}
-        ${Python3_LIBRARIES}
-    )
-    if (WIN32)
-        list(APPEND custom_ops_dependencies Python3::Python)
+    # On Windows, custom_ops should not transitively link to FFmpeg to avoid DLL issues
+    if(WIN32)
+        set(custom_ops_dependencies
+            ${Python3_LIBRARIES}
+            Python3::Python
+        )
+        # Link to core library but without transitive dependencies
+        set(custom_ops_core_dependency ${core_library_name})
+    else()
+        set(custom_ops_dependencies
+            ${core_library_name}
+            ${Python3_LIBRARIES}
+        )
+        set(custom_ops_core_dependency "")
     endif()
     make_torchcodec_sublibrary(
         "${custom_ops_library_name}"
         SHARED
         "${custom_ops_sources}"
         "${custom_ops_dependencies}"
     )
+    
+    # On Windows, link to core library privately to avoid transitive FFmpeg dependencies
+    if(WIN32 AND custom_ops_core_dependency)
+        target_link_libraries(${custom_ops_library_name} PRIVATE ${custom_ops_core_dependency})
+    endif()
 
 
     # 3. Create libtorchcodec_pybind_opsN.so.