Obs Cross Compiling

OBS Cross-Compilation

Purpose

Cross-compile OBS Studio plugins from Linux to Windows using MinGW-w64. Covers CMake presets, toolchain configuration, headers-only linking, CI/CD workflows, and artifact packaging.

When NOT to Use

• Native Windows builds with MSVC → Use obs-windows-building
• Qt/C++ frontend development → Use obs-cpp-qt-patterns
• Audio plugin implementation → Use obs-audio-plugin-writing
• Code review → Use obs-plugin-reviewing

Quick Start: Cross-Compile in 5 Steps

Step 1: Install MinGW on Linux

# Ubuntu/Debian
sudo apt install mingw-w64 gcc-mingw-w64-x86-64 g++-mingw-w64-x86-64

# Verify
x86_64-w64-mingw32-gcc --version

Step 2: Create Toolchain File

Create cmake/mingw-w64-toolchain.cmake:

# Target Windows from Linux
set(CMAKE_SYSTEM_NAME Windows)
set(CMAKE_SYSTEM_PROCESSOR x86_64)

# Cross-compilers
set(CMAKE_C_COMPILER x86_64-w64-mingw32-gcc)
set(CMAKE_CXX_COMPILER x86_64-w64-mingw32-g++)
set(CMAKE_RC_COMPILER x86_64-w64-mingw32-windres)

# Target environment (search for libraries here)
set(CMAKE_FIND_ROOT_PATH /usr/x86_64-w64-mingw32)

# Host programs (cmake, etc.) - use from host system
set(CMAKE_FIND_ROOT_PATH_MODE_PROGRAM NEVER)

# Target libraries/includes - only search in target environment
set(CMAKE_FIND_ROOT_PATH_MODE_LIBRARY ONLY)
set(CMAKE_FIND_ROOT_PATH_MODE_INCLUDE ONLY)
set(CMAKE_FIND_ROOT_PATH_MODE_PACKAGE ONLY)

# Windows flags
set(WIN32 TRUE)
set(MINGW TRUE)
set(CMAKE_SHARED_LIBRARY_SUFFIX ".dll")
set(CMAKE_EXECUTABLE_SUFFIX ".exe")

# Static link C runtime (avoid DLL dependencies)
set(CMAKE_EXE_LINKER_FLAGS "${CMAKE_EXE_LINKER_FLAGS} -static-libgcc -static-libstdc++")
set(CMAKE_SHARED_LINKER_FLAGS "${CMAKE_SHARED_LINKER_FLAGS} -static-libgcc -static-libstdc++")
set(CMAKE_MODULE_LINKER_FLAGS "${CMAKE_MODULE_LINKER_FLAGS} -static-libgcc -static-libstdc++")

# CRITICAL: Allow unresolved OBS symbols (resolved at runtime)
set(CMAKE_MODULE_LINKER_FLAGS "${CMAKE_MODULE_LINKER_FLAGS} -Wl,--unresolved-symbols=ignore-all,--warn-unresolved-symbols,--noinhibit-exec")

Step 3: Create CMakePresets.json

{
  "version": 8,
  "configurePresets": [
    {
      "name": "linux-cross-windows-x64",
      "displayName": "Cross-compile Windows x64 (from Linux)",
      "description": "Cross-compile for Windows x64 using MinGW-w64 on Linux",
      "binaryDir": "${sourceDir}/build_windows_x64",
      "condition": {
        "type": "equals",
        "lhs": "${hostSystemName}",
        "rhs": "Linux"
      },
      "generator": "Ninja",
      "toolchainFile": "${sourceDir}/cmake/mingw-w64-toolchain.cmake",
      "cacheVariables": {
        "CMAKE_BUILD_TYPE": "RelWithDebInfo",
        "CROSS_COMPILE_WINDOWS": true
      }
    }
  ],
  "buildPresets": [
    {
      "name": "linux-cross-windows-x64",
      "configurePreset": "linux-cross-windows-x64"
    }
  ]
}

Step 4: Configure Headers-Only Linking

In CMakeLists.txt:

option(CROSS_COMPILE_WINDOWS "Cross-compile for Windows from Linux" OFF)

if(CROSS_COMPILE_WINDOWS)
    # Headers only - OBS provides symbols at runtime
    add_library(obs-headers INTERFACE)
    target_include_directories(obs-headers INTERFACE
        "${OBS_SOURCE_DIR}/libobs"
        "${OBS_SOURCE_DIR}/frontend/api"
    )
    target_compile_definitions(obs-headers INTERFACE
        UNICODE _UNICODE _CRT_SECURE_NO_WARNINGS WIN32 _WIN32
    )
    target_link_libraries(${PROJECT_NAME} PRIVATE obs-headers)

    # Windows system libraries
    target_link_libraries(${PROJECT_NAME} PRIVATE ws2_32 comctl32)

    # CRITICAL: Use .def file for exports
    set_target_properties(${PROJECT_NAME} PROPERTIES
        LINK_FLAGS "${CMAKE_CURRENT_SOURCE_DIR}/src/plugin.def -Wl,--unresolved-symbols=ignore-all"
    )
else()
    # Native build - full OBS libraries
    find_package(libobs REQUIRED)
    target_link_libraries(${PROJECT_NAME} PRIVATE OBS::libobs)
endif()

Step 5: Build

# Fetch OBS SDK headers
./ci/fetch-obs-sdk.sh windows

# Configure
cmake --preset linux-cross-windows-x64 \
    -DOBS_SOURCE_DIR="$PWD/.deps/windows-x64/obs-studio-32.0.4"

# Build
cmake --build --preset linux-cross-windows-x64

# Verify
file build_windows_x64/my-plugin.dll | grep "PE32+"

Headers-Only Linking Pattern

Why headers-only? OBS plugins are loaded at runtime by OBS Studio. The plugin doesn't link against libobs.dll - instead:

1. OBS loads the plugin DLL
2. Plugin exports obs_module_load() and other functions
3. OBS provides all obs_* symbols at load time

Critical linker flags:

-Wl,--unresolved-symbols=ignore-all   # Don't fail on missing OBS symbols
-Wl,--warn-unresolved-symbols         # Downgrade to warnings
-Wl,--noinhibit-exec                  # Create output despite warnings

Symbol Export with .def File

MinGW sometimes exports functions by ordinal only. OBS requires named exports.

Create src/plugin.def:

LIBRARY my-plugin
EXPORTS
    ; Required OBS module entry points
    obs_module_load
    obs_module_unload
    obs_module_post_load
    obs_module_ver
    obs_module_set_pointer
    obs_current_module
    obs_module_description

    ; Locale functions (from OBS_MODULE_USE_DEFAULT_LOCALE)
    obs_module_set_locale
    obs_module_free_locale
    obs_module_get_string
    obs_module_text

Verify exports:

x86_64-w64-mingw32-objdump -p my-plugin.dll | grep -A 100 "Export Table"

OBS SDK Fetching

For cross-compilation, you need OBS headers (not full libraries).

Pattern from translate-live:

#!/bin/bash
# fetch-obs-sdk.sh

PLATFORM="$1"  # "windows" or "linux"
OBS_VERSION="32.0.4"
OBS_HASH="5e17f2e99..."  # From buildspec.json

# Create deps directory
mkdir -p .deps/${PLATFORM}-x64

# Download OBS source (for headers)
curl -L "https://github.com/obsproject/obs-studio/archive/refs/tags/${OBS_VERSION}.tar.gz" \
    -o obs-studio.tar.gz

# Verify checksum
echo "${OBS_HASH}  obs-studio.tar.gz" | sha256sum -c

# Extract
tar -xzf obs-studio.tar.gz -C .deps/${PLATFORM}-x64

# Create stub obsconfig.h (normally generated by CMake)
cat > .deps/${PLATFORM}-x64/obs-studio-${OBS_VERSION}/libobs/obsconfig.h << 'EOF'
#pragma once
#define OBS_VERSION "32.0.4"
#define OBS_DATA_PATH ""
#define OBS_INSTALL_PREFIX ""
#define OBS_PLUGIN_PATH ""
EOF

CI/CD Workflow

Gitea Actions / GitHub Actions

build-windows:
  name: Build Windows x64 (Cross-compile)
  runs-on: ubuntu-latest
  steps:
    - uses: actions/checkout@v4

    - name: Install dependencies
      run: |
        sudo apt-get update
        sudo apt-get install -y \
          cmake ninja-build jq curl unzip \
          mingw-w64 gcc-mingw-w64-x86-64 g++-mingw-w64-x86-64

    - name: Fetch OBS SDK
      run: ./ci/fetch-obs-sdk.sh windows

    - name: Configure
      run: |
        OBS_VERSION=$(jq -r '.dependencies["obs-studio"].version' buildspec.json)
        cmake --preset linux-cross-windows-ci-x64 \
          -DOBS_SOURCE_DIR="${PWD}/.deps/windows-x64/obs-studio-${OBS_VERSION}"

    - name: Build
      run: cmake --build --preset linux-cross-windows-ci-x64

    - name: Verify DLL
      run: |
        file build_windows_x64/my-plugin.dll | grep "PE32+"
        x86_64-w64-mingw32-objdump -p build_windows_x64/my-plugin.dll | grep -A 100 "Export Table"

    - name: Package
      run: |
        VERSION=$(jq -r '.version' buildspec.json)
        COMMIT=$(git rev-parse --short=9 HEAD)
        ARTIFACT="my-plugin-${VERSION}-windows-x64-${COMMIT}"

        mkdir -p "release/${ARTIFACT}/bin/64bit"
        cp build_windows_x64/my-plugin.dll "release/${ARTIFACT}/bin/64bit/"
        cd release && zip -rq "${ARTIFACT}.zip" "${ARTIFACT}"

Artifact Naming Convention

{plugin-name}-{version}-{platform}-{commit}.{ext}

Examples:

• my-plugin-1.0.0-linux-x86_64-abc123def.tar.xz
• my-plugin-1.0.0-windows-x64-abc123def.zip

Structure inside archive:

my-plugin-1.0.0-windows-x64-abc123def/
├── bin/
│   └── 64bit/
│       └── my-plugin.dll
└── data/
    └── locale/
        └── en-US.ini

buildspec.json Pattern

Centralize dependencies and versions:

{
  "name": "my-plugin",
  "displayName": "My OBS Plugin",
  "version": "1.0.0",
  "author": "Your Name",
  "dependencies": {
    "obs-studio": {
      "version": "32.0.4",
      "hashes": {
        "windows-x64": "5e17f2e99213af77ee15c047755ee3e3e88b78e5eee17351c113d79671ffb98b"
      }
    }
  }
}

FORBIDDEN Patterns

Troubleshooting

DLL has no exports

Symptom: Plugin loads but OBS can't find obs_module_load

Cause: Missing or incorrect .def file

Fix:

# Check exports
x86_64-w64-mingw32-objdump -p my-plugin.dll | grep -A 50 "Export Table"

# Should show named functions, not just ordinals

Undefined reference to OBS functions

Symptom: Linker errors about obs_register_source, etc.

Cause: Missing unresolved-symbols flag

Fix: Add to CMakeLists.txt:

set_target_properties(${PROJECT_NAME} PROPERTIES
    LINK_FLAGS "-Wl,--unresolved-symbols=ignore-all"
)

Wrong file format

Symptom: file shows "ELF" instead of "PE32+"

Cause: Using host compiler instead of cross-compiler

Fix: Ensure toolchain file is loaded:

cmake -DCMAKE_TOOLCHAIN_FILE=cmake/mingw-w64-toolchain.cmake ..

External Documentation

Context7 (Real-time docs)

mcp__context7__query-docs
libraryId: "/obsproject/obs-studio"
query: "CMake cross-compile Windows Linux plugin"

Official References

• OBS CMake Guide: https://docs.obsproject.com/building
• MinGW Wiki: https://www.mingw-w64.org/
• CMake Presets: https://cmake.org/cmake/help/latest/manual/cmake-presets.7.html

Related Skills

• obs-windows-building - Native Windows builds (MSVC, MinGW)
• obs-cpp-qt-patterns - Qt frontend integration
• obs-plugin-developing - Plugin architecture overview
• obs-audio-plugin-writing - Audio plugin implementation

Related Agent

Use obs-plugin-expert for coordinated guidance across all OBS plugin skills.