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diff --git a/media/libaom/src/README.md b/media/libaom/src/README.md new file mode 100644 index 000000000..cab3f9993 --- /dev/null +++ b/media/libaom/src/README.md @@ -0,0 +1,625 @@ +# AV1 Codec Library + +## Contents +1. [Building the lib and applications](#building-the-library-and-applications) + - [Prerequisites](#prerequisites) + - [Get the code](#get-the-code) + - [Basics](#basic-build) + - [Configuration options](#configuration-options) + - [Dylib builds](#dylib-builds) + - [Debugging](#debugging) + - [Cross compiling](#cross-compiling) + - [Sanitizer support](#sanitizers) + - [MSVC builds](#microsoft-visual-studio-builds) + - [Xcode builds](#xcode-builds) + - [Emscripten builds](#emscripten-builds) + - [Extra Build Flags](#extra-build-flags) +2. [Testing the library](#testing-the-av1-codec) + - [Basics](#testing-basics) + - [Unit tests](#1_unit-tests) + - [Example tests](#2_example-tests) + - [Encoder tests](#3_encoder-tests) + - [IDE hosted tests](#ide-hosted-tests) + - [Downloading test data](#downloading-the-test-data) + - [Adding a new test data file](#adding-a-new-test-data-file) + - [Additional test data](#additional-test-data) + - [Sharded testing](#sharded-testing) + - [Running tests directly](#1_running-test_libaom-directly) + - [Running tests via CMake](#2_running-the-tests-via-the-cmake-build) +3. [Coding style](#coding-style) +4. [Submitting patches](#submitting-patches) + - [Login cookie](#login-cookie) + - [Contributor agreement](#contributor-agreement) + - [Testing your code](#testing-your-code) + - [Commit message hook](#commit-message-hook) + - [Upload your change](#upload-your-change) + - [Incorporating Reviewer Comments](#incorporating-reviewer-comments) + - [Submitting your change](#submitting-your-change) + - [Viewing change status](#viewing-the-status-of-uploaded-changes) +5. [Support](#support) +6. [Bug reports](#bug-reports) + +## Building the library and applications + +### Prerequisites + + 1. [CMake](https://cmake.org) version 3.5 or higher. + 2. [Git](https://git-scm.com/). + 3. [Perl](https://www.perl.org/). + 4. For x86 targets, [yasm](http://yasm.tortall.net/), which is preferred, or a + recent version of [nasm](http://www.nasm.us/). + 5. Building the documentation requires [doxygen](http://doxygen.org). + 6. Building the unit tests requires [Python](https://www.python.org/). + 7. Emscripten builds require the portable + [EMSDK](https://kripken.github.io/emscripten-site/index.html). + +### Get the code + +The AV1 library source code is stored in the Alliance for Open Media Git +repository: + +~~~ + $ git clone https://aomedia.googlesource.com/aom + # By default, the above command stores the source in the aom directory: + $ cd aom +~~~ + +### Basic build + +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. + +### Configuration options + +The AV1 codec library has a great many configuration options. These come in two +varieties: + + 1. Build system configuration options. These have the form `ENABLE_FEATURE`. + 2. 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 the AV1 encoder: + +~~~ + $ cmake path/to/aom -DENABLE_CCACHE=1 -DCONFIG_AV1_ENCODER=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`. + +### Dylib builds + +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 -DBUILD_SHARED_LIBS=1 + $ make +~~~ + +This is currently only supported on non-Windows targets. + +### Debugging + +Depending on the generator used there are multiple ways of going about +debugging AV1 components. For single configuration generators like the Unix +Makefiles generator, setting `CMAKE_BUILD_TYPE` to Debug is sufficient: + +~~~ + $ cmake path/to/aom -DCMAKE_BUILD_TYPE=Debug +~~~ + +For Xcode, mainly because configuration controls for Xcode builds are buried two +configuration windows deep and must be set for each subproject within the Xcode +IDE individually, `CMAKE_CONFIGURATION_TYPES` should be set to Debug: + +~~~ + $ cmake path/to/aom -G Xcode -DCMAKE_CONFIGURATION_TYPES=Debug +~~~ + +For Visual Studio the in-IDE configuration controls should be used. Simply set +the IDE project configuration to Debug to allow for stepping through the code. + +In addition to the above it can sometimes be useful to debug only C and C++ +code. To disable all assembly code and intrinsics set `AOM_TARGET_CPU` to +generic at generation time: + +~~~ + $ cmake path/to/aom -DAOM_TARGET_CPU=generic +~~~ + +### Cross compiling + +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 + - arm64-mingw-gcc.cmake + - armv7-ios.cmake + - armv7-linux-gcc.cmake + - armv7-mingw-gcc.cmake + - armv7s-ios.cmake + - mips32-linux-gcc.cmake + - mips64-linux-gcc.cmake + - x86-ios-simulator.cmake + - x86-linux.cmake + - x86-macos.cmake + - x86-mingw-gcc.cmake + - x86\_64-ios-simulator.cmake + - x86\_64-mingw-gcc.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. + +### Sanitizers + +Sanitizer integration is built-in to the CMake build system. To enable a +sanitizer, add `-DSANITIZE=<type>` to the CMake command line. For example, to +enable address sanitizer: + +~~~ + $ cmake path/to/aom -DSANITIZE=address + $ make +~~~ + +Sanitizers available vary by platform, target, and compiler. Consult your +compiler documentation to determine which, if any, are available. + +### Microsoft Visual Studio builds + +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" +~~~ + +### Xcode builds + +Building the AV1 codec library in Xcode is supported. The following example +demonstrates generating an Xcode project: + +~~~ + $ cmake path/to/aom -G Xcode +~~~ + +### Emscripten builds + +Building the AV1 codec library with Emscripten is supported. Typically this is +used to hook into the AOMAnalyzer GUI application. These instructions focus on +using the inspector with AOMAnalyzer, but all tools can be built with +Emscripten. + +It is assumed here that you have already downloaded and installed the EMSDK, +installed and activated at least one toolchain, and setup your environment +appropriately using the emsdk\_env script. + +1. Download [AOMAnalyzer](https://people.xiph.org/~mbebenita/analyzer/). + +2. Configure the build: + +~~~ + $ cmake path/to/aom \ + -DENABLE_CCACHE=1 \ + -DAOM_TARGET_CPU=generic \ + -DENABLE_DOCS=0 \ + -DENABLE_TESTS=0 \ + -DCONFIG_ACCOUNTING=1 \ + -DCONFIG_INSPECTION=1 \ + -DCONFIG_MULTITHREAD=0 \ + -DCONFIG_RUNTIME_CPU_DETECT=0 \ + -DCONFIG_WEBM_IO=0 \ + -DCMAKE_TOOLCHAIN_FILE=path/to/emsdk-portable/.../Emscripten.cmake +~~~ + +3. Build it: run make if that's your generator of choice: + +~~~ + $ make inspect +~~~ + +4. Run the analyzer: + +~~~ + # inspect.js is in the examples sub directory of the directory in which you + # executed cmake. + $ path/to/AOMAnalyzer path/to/examples/inspect.js path/to/av1/input/file +~~~ + +### Extra build flags + +Three variables allow for passing of additional flags to the build system. + +- AOM\_EXTRA\_C\_FLAGS +- AOM\_EXTRA\_CXX\_FLAGS +- AOM\_EXTRA\_EXE\_LINKER\_FLAGS + +The build system attempts to ensure the flags passed through the above variables +are passed to tools last in order to allow for override of default behavior. +These flags can be used, for example, to enable asserts in a release build: + +~~~ + $ cmake path/to/aom \ + -DCMAKE_BUILD_TYPE=Release \ + -DAOM_EXTRA_C_FLAGS=-UNDEBUG \ + -DAOM_EXTRA_CXX_FLAGS=-UNDEBUG +~~~ + +## Testing the AV1 codec + +### Testing basics + +There are several methods of testing the AV1 codec. All of these methods require +the presence of the AV1 source code and a working build of the AV1 library and +applications. + +#### 1. Unit 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 +~~~ + +#### 2. Example tests: + +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 +~~~ + +#### 3. Encoder tests: + +When making a change to the encoder run encoder tests to confirm that your +change has a positive or negligible impact on encode quality. When running these +tests the build configuration should be changed to enable internal encoder +statistics: + +~~~ + $ cmake path/to/aom -DCONFIG_INTERNAL_STATS=1 + $ make +~~~ + +The repository contains scripts intended to make running these tests as simple +as possible. The following example demonstrates creating a set of baseline clips +for comparison to results produced after making your change to libaom: + +~~~ + # This will encode all Y4M files in the current directory using the + # settings specified to create the encoder baseline statistical data: + $ cd path/to/test/inputs + # This command line assumes that run_encodes.sh, its helper script + # best_encode.sh, and the aomenc you intend to test are all within a + # directory in your PATH. + $ run_encodes.sh 200 500 50 baseline +~~~ + +After making your change and creating the baseline clips, you'll need to run +encodes that include your change(s) to confirm that things are working as +intended: + +~~~ + # This will encode all Y4M files in the current directory using the + # settings specified to create the statistical data for your change: + $ cd path/to/test/inputs + # This command line assumes that run_encodes.sh, its helper script + # best_encode.sh, and the aomenc you intend to test are all within a + # directory in your PATH. + $ run_encodes.sh 200 500 50 mytweak +~~~ + +After creating both data sets you can use `test/visual_metrics.py` to generate a +report that can be viewed in a web browser: + +~~~ + $ visual_metrics.py metrics_template.html "*stt" baseline mytweak \ + > mytweak.html +~~~ + +You can view the report by opening mytweak.html in a web browser. + + +### IDE hosted tests + +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 +~~~ + +### Downloading the test data + +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. + +### Adding a new test data file + +First, add the new test data file to the `aom-test-data` bucket of the +`aomedia-testing` project on Google Cloud Platform. You may need to ask someone +with the necessary access permissions to do this for you. + +NOTE: When a new test data file is added to the `aom-test-data` bucket, its +"Public access" is initially "Not public". We need to change its +"Public access" to "Public" by using the following +[`gsutil`](https://cloud.google.com/storage/docs/gsutil_install) command: +~~~ + $ gsutil acl ch -g all:R gs://aom-test-data/test-data-file-name +~~~ +This command grants the `AllUsers` group READ access to the file named +"test-data-file-name" in the `aom-test-data` bucket. + +Once the new test data file has been added to `aom-test-data`, create a CL to +add the name of the new test data file to `test/test_data_util.cmake` and add +the SHA1 checksum of the new test data file to `test/test-data.sha1`. (The SHA1 +checksum of a file can be calculated by running the `sha1sum` command on the +file.) + +### Additional test data + +The test data mentioned above is strictly intended for unit testing. + +Additional input data for testing the encoder can be obtained from: +https://media.xiph.org/video/derf/ + +### Sharded testing + +The AV1 codec library unit tests are built upon gtest which supports sharding of +test jobs. Sharded test runs can be achieved in a couple of ways. + +#### 1. Running test\_libaom directly: + +~~~ + # Set the environment variable GTEST_TOTAL_SHARDS to control the number of + # shards. + $ export GTEST_TOTAL_SHARDS=10 + # (GTEST shard indexing is 0 based). + $ seq 0 $(( $GTEST_TOTAL_SHARDS - 1 )) \ + | xargs -n 1 -P 0 -I{} env GTEST_SHARD_INDEX={} ./test_libaom +~~~ + +To create a test shard for each CPU core available on the current system set +`GTEST_TOTAL_SHARDS` to the number of CPU cores on your system minus one. + +#### 2. Running the tests via the CMake build: + +~~~ + # For IDE based builds, ENABLE_IDE_TEST_HOSTING must be enabled. See + # the IDE hosted tests section above for more information. If the IDE + # supports building targets concurrently tests will be sharded by default. + + # For make and ninja builds the -j parameter controls the number of shards + # at test run time. This example will run the tests using 10 shards via + # make. + $ make -j10 runtests +~~~ + +The maximum number of test targets that can run concurrently is determined by +the number of CPUs on the system where the build is configured as detected by +CMake. A system with 24 cores can run 24 test shards using a value of 24 with +the `-j` parameter. When CMake is unable to detect the number of cores 10 shards +is the default maximum value. + +## Coding style + +We are using the Google C Coding Style defined by the +[Google C++ Style Guide](https://google.github.io/styleguide/cppguide.html). + +The coding style used by this project is enforced with clang-format using the +configuration contained in the +[.clang-format](https://chromium.googlesource.com/webm/aom/+/master/.clang-format) +file in the root of the repository. + +You can download clang-format using your system's package manager, or directly +from [llvm.org](http://llvm.org/releases/download.html). You can also view the +[documentation](https://clang.llvm.org/docs/ClangFormat.html) on llvm.org. +Output from clang-format varies by clang-format version, for best results your +version should match the one used on Jenkins. You can find the clang-format +version by reading the comment in the `.clang-format` file linked above. + +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. + +Some Git installations have clang-format integration. Here are some examples: + +~~~ + # Apply clang-format to all staged changes: + $ git clang-format + + # Clang format all staged and unstaged changes: + $ git clang-format -f + + # Clang format all staged and unstaged changes interactively: + $ git clang-format -f -p +~~~ + +## Submitting patches + +We manage the submission of patches using the +[Gerrit](https://www.gerritcodereview.com/) code review tool. This tool +implements a workflow on top of the Git version control system to ensure that +all changes get peer reviewed and tested prior to their distribution. + +### Login cookie + +Browse to [AOMedia Git index](https://aomedia.googlesource.com/) and login with +your account (Gmail credentials, for example). Next, follow the +`Generate Password` Password link at the top of the page. You’ll be given +instructions for creating a cookie to use with our Git repos. + +### Contributor agreement + +You will be required to execute a +[contributor agreement](http://aomedia.org/license) to ensure that the AOMedia +Project has the right to distribute your changes. + +### Testing your code + +The testing basics are covered in the [testing section](#testing-the-av1-codec) +above. + +In addition to the local tests, many more (e.g. asan, tsan, valgrind) will run +through Jenkins instances upon upload to gerrit. + +### Commit message hook + +Gerrit requires that each submission include a unique Change-Id. You can assign +one manually using git commit --amend, but it’s easier to automate it with the +commit-msg hook provided by Gerrit. + +Copy commit-msg to the `.git/hooks` directory of your local repo. Here's an +example: + +~~~ + $ curl -Lo aom/.git/hooks/commit-msg https://chromium-review.googlesource.com/tools/hooks/commit-msg + + # Next, ensure that the downloaded commit-msg script is executable: + $ chmod u+x aom/.git/hooks/commit-msg +~~~ + +See the Gerrit +[documentation](https://gerrit-review.googlesource.com/Documentation/user-changeid.html) +for more information. + +### Upload your change + +The command line to upload your patch looks like this: + +~~~ + $ git push https://aomedia-review.googlesource.com/aom HEAD:refs/for/master +~~~ + +### Incorporating reviewer comments + +If you previously uploaded a change to Gerrit and the Approver has asked for +changes, follow these steps: + +1. Edit the files to make the changes the reviewer has requested. +2. Recommit your edits using the --amend flag, for example: + +~~~ + $ git commit -a --amend +~~~ + +3. Use the same git push command as above to upload to Gerrit again for another + review cycle. + +In general, you should not rebase your changes when doing updates in response to +review. Doing so can make it harder to follow the evolution of your change in +the diff view. + +### Submitting your change + +Once your change has been Approved and Verified, you can “submit” it through the +Gerrit UI. This will usually automatically rebase your change onto the branch +specified. + +Sometimes this can’t be done automatically. If you run into this problem, you +must rebase your changes manually: + +~~~ + $ git fetch + $ git rebase origin/branchname +~~~ + +If there are any conflicts, resolve them as you normally would with Git. When +you’re done, reupload your change. + +### Viewing the status of uploaded changes + +To check the status of a change that you uploaded, open +[Gerrit](https://aomedia-review.googlesource.com/), sign in, and click My > +Changes. + +## Support + +This library is an open source project supported by its community. Please +please email aomediacodec@jointdevelopment.kavi.com for help. + +## Bug reports + +Bug reports can be filed in the Alliance for Open Media +[issue tracker](https://bugs.chromium.org/p/aomedia/issues/list). |