- CMake version 3.5 or higher.
- Git.
- Perl.
- For x86 targets, yasm, which is preferred, or a recent version of nasm.
- Building the documentation requires doxygen.
- Building the unit tests requires Python.
CMake replaces the configure step typical of many projects. Running CMake will produce configuration and build files for the currently selected CMake generator. For most systems the default generator is Unix Makefiles. The basic form of a makefile build is the following:
$ cmake path/to/aom
$ make
The above will generate a makefile build that produces the AV1 library and applications for the current host system after the make step completes successfully. The compiler chosen varies by host platform, but a general rule applies: On systems where cc and c++ are present in $PATH at the time CMake is run the generated build will use cc and c++ by default.
The AV1 codec library has a great many configuration options. These come in two varieties:
- Build system configuration options. These have the form
ENABLE_FEATURE. - AV1 codec configuration options. These have the form
CONFIG_FEATURE.
Both types of options are set at the time CMake is run. The following example enables ccache and disables high bit depth:
$ cmake path/to/aom -DENABLE_CCACHE=1 -DCONFIG_HIGHBITDEPTH=0
$ make
The available configuration options are too numerous to list here. Build system
configuration options can be found at the top of the CMakeLists.txt file found
in the root of the AV1 repository, and AV1 codec configuration options can
currently be found in the file build/cmake/aom_config_defaults.cmake.
A dylib (shared object) build of the AV1 codec library can be enabled via the CMake built in variable BUILD_SHARED_LIBS:
$ cmake path/to/aom -D BUILD_SHARED_LIBS=1
$ make
This is currently only supported on non-Windows targets.
For the purposes of building the AV1 codec and applications and relative to the scope of this guide, all builds for architectures differing from the native host architecture will be considered cross compiles. The AV1 CMake build handles cross compiling via the use of toolchain files included in the AV1 repository. The toolchain files available at the time of this writing are:
- arm64-ios.cmake
- arm64-linux-gcc.cmake
- armv7-ios.cmake
- armv7-linux-gcc.cmake
- armv7s-ios.cmake
- mips32-linux-gcc.cmake
- mips64-linux-gcc.cmake
- x86-ios-simulator.cmake
- x86-linux.cmake
- x86-macos.cmake
- x86_64-ios-simulator.cmake
The following example demonstrates use of the x86-macos.cmake toolchain file on a x86_64 MacOS host:
$ cmake path/to/aom \
-DCMAKE_TOOLCHAIN_FILE=path/to/aom/build/cmake/toolchains/x86-macos.cmake
$ make
To build for an unlisted target creation of a new toolchain file is the best solution. The existing toolchain files can be used a starting point for a new toolchain file since each one exposes the basic requirements for toolchain files as used in the AV1 codec build.
As a temporary work around an unoptimized AV1 configuration that builds only C and C++ sources can be produced using the following commands:
$ cmake path/to/aom -DAOM_TARGET_CPU=generic
$ make
In addition to the above it's important to note that the toolchain files suffixed with gcc behave differently than the others. These toolchain files attempt to obey the $CROSS environment variable.
Building the AV1 codec library in Microsoft Visual Studio is supported. The following example demonstrates generating projects and a solution for the Microsoft IDE:
# This does not require a bash shell; command.exe is fine.
$ cmake path/to/aom -G "Visual Studio 15 2017"
Building the AV1 codec library in Xcode is supported. The following example demonstrates generating an Xcode project:
$ cmake path/to/aom -G Xcode
Currently there are two types of tests in the AV1 codec repository:
- Unit tests.
- Example tests.
The unit tests can be run at build time:
# Before running the make command the LIBAOM_TEST_DATA_PATH environment
# variable should be set to avoid downloading the test files to the
# cmake build configuration directory.
$ cmake path/to/aom
# Note: The AV1 CMake build creates many test targets. Running make
# with multiple jobs will speed up the test run significantly.
$ make runtests
The example tests require a bash shell and can be run in the following manner:
# See the note above about LIBAOM_TEST_DATA_PATH above.
$ cmake path/to/aom
$ make
# It's best to build the testdata target using many make jobs.
# Running it like this will verify and download (if necessary)
# one at a time, which takes a while.
$ make testdata
$ path/to/aom/test/examples.sh --bin-path examples
By default the generated projects files created by CMake will not include the
runtests and testdata rules when generating for IDEs like Microsoft Visual
Studio and Xcode. This is done to avoid intolerably long build cycles in the
IDEs-- IDE behavior is to build all targets when selecting the build project
options in MSVS and Xcode. To enable the test rules in IDEs the
ENABLE_IDE_TEST_HOSTING variable must be enabled at CMake generation time:
# This example uses Xcode. To get a list of the generators
# available, run cmake with the -G argument missing its
# value.
$ cmake path/to/aom -DENABLE_IDE_TEST_HOSTING=1 -G Xcode
The fastest and easiest way to obtain the test data is to use CMake to generate a build using the Unix Makefiles generator, and then to build only the testdata rule:
$ cmake path/to/aom -G "Unix Makefiles"
# 28 is used because there are 28 test files as of this writing.
$ make -j28 testdata
The above make command will only download and verify the test data.
The coding style used by this project is enforced with clang-format using the configuration contained in the .clang-format file in the root of the repository.
Before pushing changes for review you can format your code with:
# Apply clang-format to modified .c, .h and .cc files
$ clang-format -i --style=file \
$(git diff --name-only --diff-filter=ACMR '*.[hc]' '*.cc')
Check the .clang-format file for the version used to generate it if there is any difference between your local formatting and the review system.
See also: http://clang.llvm.org/docs/ClangFormat.html
This library is an open source project supported by its community. Please please email [email protected] for help.
Bug reports can be filed in the Alliance for Open Media issue tracker.
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