it appears a one-character typo in the cmake_minimum_required line prevents it from compiling under CMake 4.0. in order to fix that, I had to take this thing out of submodules... it is recommended to do this after you pull; git submodule deinit extern/libsndfile
		
			
				
	
	
		
			320 lines
		
	
	
		
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			Markdown
		
	
	
	
	
	
			
		
		
	
	
			320 lines
		
	
	
		
			13 KiB
		
	
	
	
		
			Markdown
		
	
	
	
	
	
NOTICE: THIS IS A MODIFIED VERSION OF LIBSNDFILE WHICH FIXES COMPILATION WHEN USING CMAKE 4.0.
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---
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# libsndfile
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libsndfile is a C library for reading and writing files containing sampled audio
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data.
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## Authors
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The libsndfile project was originally developed and maintained by
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Erik de Castro Lopo <erikd@mega-nerd.com> aka @erikd. The project was developed
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on Github at <https://github.com/erikd/libsndfile>.
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After the release of version 1.0.30, @erikd transferred the project to
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[the libsndfile team](https://github.com/libsndfile), see [AUTHORS](AUTHORS)
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for details.
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## Hacking
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The canonical source code repository for libsndfile is at
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<https://github.com/libsndfile/libsndfile>.
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You can grab the source code using:
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    git clone https://github.com/libsndfile/libsndfile.git
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For building for Android see [BuildingForAndroid][BuildingForAndroid].
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There are currently two build systems: the traditional GNU autotool based one and
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modern CMake based build system. Use of the CMake build system is documented
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below.
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Setting up a build environment for libsndfile on Debian or Ubuntu is as simple as:
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    sudo apt install autoconf autogen automake build-essential libasound2-dev \
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      libflac-dev libogg-dev libtool libvorbis-dev libopus-dev libmp3lame-dev \
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      libmpg123-dev pkg-config python
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For other Linux distributions or any of the *BSDs, the setup should be similar
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although the package install tools and package names may be slightly different.
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Similarly on Mac OS X, assuming [brew] is already installed:
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    brew install autoconf autogen automake flac libogg libtool libvorbis opus mpg123 pkg-config
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Once the build environment has been set up, building and testing libsndfile is
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as simple as:
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    autoreconf -vif
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    ./configure --enable-werror
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    make
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    make check
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## The CMake build system
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Although Autotools is the primary and recommended build toolchain, CMake meta
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build generator is also available. The build process with CMake takes
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place in two stages. First, standard build files are created from configuration
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scripts. Then the platform's native build tools are used for the actual
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building. CMake can produce Microsoft Visual Studio project and solution files,
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Unix Makefiles, Xcode projects and [many more](https://cmake.org/cmake/help/latest/manual/cmake-generators.7.html).
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Some IDE support CMake natively or with plugins, check you IDE documentation
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 for details.
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### Requirements
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1. C99-compliant compiler toolchain (tested with GCC, Clang and Visual
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   Studio 2015)
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2. CMake 3.1.3 or newer
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There are some recommended packages to enable all features of libsndfile:
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1. Ogg, Vorbis and FLAC libraries and headers to enable these formats support
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2. ALSA development package under Linux to build sndfile-play utility
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3. Sndio development package under BSD to build sndfile-play utility
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### Building from command line
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CMake can handle out-of-place builds, enabling several builds from
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the same source tree, and cross-compilation. The ability to build a directory
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tree outside the source tree is a key feature, ensuring that if a build
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directory is removed, the source files remain unaffected.
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    mkdir CMakeBuild
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    cd CMakeBuild
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Then run `cmake` command with directory where CMakeLists.txt script is located
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as argument (relative paths are supported):
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    cmake ..
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This command will configure and write build script or solution to CMakeBuild
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directory. CMake is smart enough to create Unix makefiles under Linux or Visual
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Studio solution if you have Visual Studio installed, but you can configure
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[generator](https://cmake.org/cmake/help/latest/manual/cmake-generators.7.html)
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with `-G` command line parameter:
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    cmake .. -G"Unix Makefiles"
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The build procedure depends on the selected generator. With "Unix Makefiles" you
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can type:
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    make & make install
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With "Visual Studio" and some other generators you can open solution or project
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from `CMakeBuild` directory and build using IDE.
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Finally, you can use unified command:
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    cmake --build .
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CMake also provides Qt-based cross platform GUI, cmake-gui. Using it is trivial
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and does not require detailed explanations.
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### Configuring CMake
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You can pass additional options with `/D<parameter>=<value>` when you run
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`cmake` command. Some useful system options:
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* `CMAKE_C_FLAGS` - additional C compiler flags
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* `CMAKE_BUILD_TYPE` - configuration type, `DEBUG`, `RELEASE`, `RELWITHDEBINFO`
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  or `MINSIZEREL`. `DEBUG` is default
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* `CMAKE_INSTALL_PREFIX` - build install location, the same as `--prefix` option
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  of `configure` script
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 Useful libsndfile options:
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* `BUILD_SHARED_LIBS` - build shared library (DLL under Windows) when `ON`,
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  build static library othervise. This option is `OFF` by default.
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* `BUILD_PROGRAMS` - build libsndfile's utilities from `programs/` directory,
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  `ON` by default.
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* `BUILD_EXAMPLES` - build examples, `ON` by default.
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* `BUILD_TESTING` - build tests. Then you can run tests with `ctest` command,
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  `ON` by default. Setting `BUILD_SHARED_LIBS` to `ON` disables this option.
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* `ENABLE_EXTERNAL_LIBS` - enable Ogg, Vorbis, FLAC and Opus support. This
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  option is available and set to `ON` if all dependency libraries were found.
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* `ENABLE_MPEG` - MP3 support. This option is available and set to `ON` if all
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  dependency libraries were found.
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* `ENABLE_CPU_CLIP` - enable tricky cpu specific clipper. Enabled and set to
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  `ON` when CPU clips negative\positive. Don't touch it if you are not sure
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* `ENABLE_BOW_DOCS` - enable black-on-white documentation theme, `OFF` by
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  default.
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* `ENABLE_EXPERIMENTAL` - enable experimental code. Don't use it if you are
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  not sure. This option is `OFF` by default.
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* `ENABLE_CPACK` - enable [CPack](https://cmake.org/cmake/help/latest/module/CPack.html) support.
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  This option is `ON` by default.
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* `ENABLE_PACKAGE_CONFIG` - generate and install [package config file](https://cmake.org/cmake/help/latest/manual/cmake-packages.7.html#config-file-packages).
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* `INSTALL_PKGCONFIG_MODULE` - generate and install [pkg-config module](https://people.freedesktop.org/~dbn/pkg-config-guide.html).
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* `INSTALL_MANPAGES` - install [man pages](https://en.wikipedia.org/wiki/Man_page) for programs. This option is `ON` by  default
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* `ENABLE_STATIC_RUNTIME` - enable static runtime on Windows platform (MSVC and
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  MinGW), `OFF` by default.
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  **Note**: For MSVC compiler this option is deprecated for CMake >= 3.15, see
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  policy [CMP0091](https://cmake.org/cmake/help/latest/policy/CMP0091.html).
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  Use `CMAKE_MSVC_RUNTIME_LIBRARY` option instead.
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  **Note**: For MinGW toolchain this option is experimental. If you enabled it
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  and then disabled again, you need to clear CMake cache (delete CMakeCache.txt).
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* `ENABLE_COMPATIBLE_LIBSNDFILE_NAME` - set DLL name to `libsndfile-1.dll`
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  (canonical name) on Windows platform, `sndfile.dll` otherwise, `OFF` by
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  default. Library name can be different depending on platform. The well known
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  DLL name on Windows platform is `libsndfile-1.dll`, because the only way to
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  build Windows library before was MinGW toolchain with Autotools. This name
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  is native for MinGW ecosystem, Autotools constructs it using MinGW platform
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  rules from `sndfile` target. But when you build with CMake using native
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  Windows compiler, the name is `sndfile.dll`. This is name for native Windows
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  platform, because Windows has no library naming rules. It is preffered
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  because you can search library using package manager or CMake's
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  `find_library` command on any platform using the same `sndfile` name.
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* `ENABLE_SSE2` - add compiler flag to enable SSE2 if required, `ON` by default.
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  This option is for X86 and GCC compatible compilers configurations only.
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  If you compile for other SIMD set, e.g. AVX2, you may want to set
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  `ENABLE_SSE2` to `OFF`.
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  **Note**: This option is not active for X64 configuration, because SSE2 is
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  always available in this mode and all optimizations are enabled by default.
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Deprecated options:
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* `DISABLE_EXTERNAL_LIBS` - disable Ogg, Vorbis and FLAC support. Replaced by
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  `ENABLE_EXTERNAL_LIBS`
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* `DISABLE_CPU_CLIP` - disable tricky cpu specific clipper. Replaced by
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  `ENABLE_CPU_CLIP`
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* `BUILD_STATIC_LIBS` - build static library. Use `BUILD_SHARED_LIBS` instead
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### Linking from CMake projects
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First you need to add `FindOgg.cmake`, `FindVorbis.cmake`, `FindFLAC.cmake` and
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`FindOpus.cmake` files to some directory inside your CMake project (usually
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`cmake`) and add it to `CMAKE_MODULE_PATH`:
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    project(SomeApplication)
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    list(APPEND CMAKE_MODULE_PATH ${CMAKE_CURRENT_SOURCE_DIR}/cmake)
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Now you can search `libsndfile` library from your `CMakeLists.txt`
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 with this command:
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    find_package(SndFile)
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`SndFile_FOUND` is set to `ON` when library is found.
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If `libsndfile` dependency is critical, you can add `REQUIRED` to
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 `find_package`:
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    find_package(SndFile REQUIRED)
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With with option `find_package` will terminate configuration process
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 if `libsndfile` is not found.
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You can also add version check:
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    find_package(SndFile 1.0.29)
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`find_package` will report error, if `libsndfile` version is < 1.0.29.
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You can combine `REQUIRED` and version if you need.
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To link `libsndfile` library use:
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    target_link_libraries(my_application PRIVATE SndFile::sndfile)
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### Notes for Windows users
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#### System CRT library
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First advice about Visual Studio [system CRT libraries](https://docs.microsoft.com/en-us/cpp/c-runtime-library/c-run-time-library-reference?view=vs-2019),
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it is system code linked as static or dynamic library to every C application.
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You can find related option in Visual Studio project properties:
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    C/C++ -> Code Generation -> Runtime Library
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Dynamic version of system CRT library is default and it means that end user needs
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to have the same runtime library installed on his system. Most likely it is so,
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but if it is not, the user will see this error message using libsndfile DLL:
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    "The program can't start because <crt-dll-name>.dll is missing from your computer. Try reinstalling the program to fix this problem. "
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To avoid this, you may want to enable static CRT library linking. In this case
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the size of your DLL will increase slightly the size will increase slightly, but
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you can redistribute the libsndfile DLL without having to install the correct
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version of the system CRT library.
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CMake project will use dynamic system CRT libraries by default, just like
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Visual Studio does. But you can change it using `ENABLE_STATIC_RUNTIME` or
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`CMAKE_MSVC_RUNTIME_LIBRARY` options.
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**Note**: You cannot use both options at the same time, it will lead to a
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configuration error.
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If you have CMake >= 3.15 you should use
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[`CMAKE_MSVC_RUNTIME_LIBRARY`](https://cmake.org/cmake/help/v3.15/variable/CMAKE_MSVC_RUNTIME_LIBRARY.html) option.
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This will enable static linking:
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    cmake .. -D"MultiThreaded$<$<CONFIG:Debug>:Debug>"
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You can use libsndfile `ENABLE_STATIC_RUNTIME` option to to control CRT library
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linking for CMake project: `OFF` or unset (default) for dynamic, and `ON` for
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static linking:
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    cmake .. -DENABLE_STATIC_RUNTIME=ON
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**Note**: This option is deprecated and may be removed in far future because we
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have standard option `CMAKE_MSVC_RUNTIME_LIBRARY` now.
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#### Using Vcpkg package manager
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Second advice is about Ogg, Vorbis FLAC and Opus support. Searching external
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libraries under Windows is a little bit tricky. The best way is to use
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[Vcpkg](https://github.com/Microsoft/vcpkg).
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Install Vcpkg and then add this parameter to cmake command line:
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    -DCMAKE_TOOLCHAIN_FILE=<path-to-vcpkg>/scripts/buildsystems/vcpkg.cmake
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You also need to set `VCPKG_TARGET_TRIPLET` if you want to use static libraries:
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    -DVCPKG_TARGET_TRIPLET=x64-windows-static
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Then you need to install static libogg, libvorbis, libflac, libopus, mpg123 and
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mp3lame Vcpkg packages.
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After 1.1.0beta2 you don't need to install dependencies manually. Libsndfile
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now supports [Vcpkg manifest mode](https://vcpkg.readthedocs.io/en/latest/users/manifests/)
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and all dependencies are installed automatically.
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However, you can turn off the manifest mode and return to the classic mode using
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the `VCPKG_MANIFEST_MODE` parameter from the command line:
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    -DVCPKG_MANIFEST_MODE=OFF
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In classic mode, you need to install the required libraries manually:
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    vcpkg install libvorbis:x64-windows-static libflac:x64-windows-static
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    opus:x64-windows-static mp3lame:x86-windows-static mpg123:x86-windows-static
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    libvorbis:x86-windows-static libflac:x86-windows-static
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    opus:x86-windows-static mp3lame:x86-windows-static mpg123:x86-windows-static
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**Note**: Use must use the same CRT library for external libraries and the
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libsndfile library itself. For `*-static` triplets Vcpkg uses
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[static CRT](https://vcpkg.readthedocs.io/en/latest/users/triplets/).
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## Submitting Patches
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See [CONTRIBUTING.md](CONTRIBUTING.md) for details.
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[brew]: http://brew.sh/
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[github]: http://libsndfile.github.io/libsndfile/
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[BuildingForAndroid]: https://github.com/libsndfile/libsndfile/blob/master/Building-for-Android.md
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