README.md
1README.md {#LREADME}
2=========
3# AV1 Codec Library
4
5## Contents
61. [Building the lib and applications](#building-the-library-and-applications)
7 - [Prerequisites](#prerequisites)
8 - [Get the code](#get-the-code)
9 - [Basics](#basic-build)
10 - [Configuration options](#configuration-options)
11 - [Dylib builds](#dylib-builds)
12 - [Debugging](#debugging)
13 - [Cross compiling](#cross-compiling)
14 - [Sanitizer support](#sanitizers)
15 - [MSVC builds](#microsoft-visual-studio-builds)
16 - [Xcode builds](#xcode-builds)
17 - [Emscripten builds](#emscripten-builds)
18 - [Extra Build Flags](#extra-build-flags)
19 - [Build with VMAF support](#build-with-vmaf)
202. [Testing the library](#testing-the-av1-codec)
21 - [Basics](#testing-basics)
22 - [Unit tests](#unit-tests)
23 - [Example tests](#example-tests)
24 - [Encoder tests](#encoder-tests)
25 - [IDE hosted tests](#ide-hosted-tests)
26 - [Downloading test data](#downloading-the-test-data)
27 - [Adding a new test data file](#adding-a-new-test-data-file)
28 - [Additional test data](#additional-test-data)
29 - [Sharded testing](#sharded-testing)
30 - [Running tests directly](#running-test_libaom-directly)
31 - [Running tests via CMake](#running-the-tests-via-the-cmake-build)
323. [Coding style](#coding-style)
334. [Submitting patches](#submitting-patches)
34 - [Login cookie](#login-cookie)
35 - [Contributor agreement](#contributor-agreement)
36 - [Testing your code](#testing-your-code)
37 - [Commit message hook](#commit-message-hook)
38 - [Upload your change](#upload-your-change)
39 - [Incorporating Reviewer Comments](#incorporating-reviewer-comments)
40 - [Submitting your change](#submitting-your-change)
41 - [Viewing change status](#viewing-the-status-of-uploaded-changes)
425. [Support](#support)
436. [Bug reports](#bug-reports)
44
45## Building the library and applications {#building-the-library-and-applications}
46
47### Prerequisites {#prerequisites}
48
491. [CMake](https://cmake.org). See CMakeLists.txt for the minimum version
50 required.
512. [Git](https://git-scm.com/).
523. A modern C compiler. gcc 6+, clang 7+, Microsoft Visual Studio 2019+ or
53 the latest version of MinGW-w64 (clang64 or ucrt toolchains) are
54 recommended. A C++ compiler is necessary to build the unit tests and some
55 features contained in the examples.
564. [Perl](https://www.perl.org/).
575. For x86 targets, [yasm](http://yasm.tortall.net/) or a recent version (2.14
58 or later) of [nasm](http://www.nasm.us/). (If both yasm and nasm are
59 present, yasm will be used by default. Pass -DENABLE_NASM=ON to cmake to
60 select nasm.) If you download yasm with the intention to work with Visual
61 Studio, please download win32.exe or win64.exe and rename it into yasm.exe.
62 DO NOT download or use vsyasm.exe.
636. Building the documentation requires
64 [doxygen version 1.8.10 or newer](http://doxygen.org).
657. Emscripten builds require the portable
66 [EMSDK](https://kripken.github.io/emscripten-site/index.html).
67
68### Get the code {#get-the-code}
69
70The AV1 library source code is stored in the Alliance for Open Media Git
71repository:
72
73~~~
74 $ git clone https://aomedia.googlesource.com/aom
75 # By default, the above command stores the source in the aom directory:
76 $ cd aom
77~~~
78
79### Basic build {#basic-build}
80
81CMake replaces the configure step typical of many projects. Running CMake will
82produce configuration and build files for the currently selected CMake
83generator. For most systems the default generator is Unix Makefiles. The basic
84form of a makefile build is the following:
85
86~~~
87 $ cmake path/to/aom
88 $ make
89~~~
90
91The above will generate a makefile build that produces the AV1 library and
92applications for the current host system after the make step completes
93successfully. The compiler chosen varies by host platform, but a general rule
94applies: On systems where cc and c++ are present in $PATH at the time CMake is
95run the generated build will use cc and c++ by default.
96
97### Configuration options {#configuration-options}
98
99The AV1 codec library has a great many configuration options. These come in two
100varieties:
101
102 1. Build system configuration options. These have the form `ENABLE_FEATURE`.
103 2. AV1 codec configuration options. These have the form `CONFIG_FEATURE`.
104
105Both types of options are set at the time CMake is run. The following example
106enables ccache and disables the AV1 encoder:
107
108~~~
109 $ cmake path/to/aom -DENABLE_CCACHE=1 -DCONFIG_AV1_ENCODER=0
110 $ make
111~~~
112
113The available configuration options are too numerous to list here. Build system
114configuration options can be found at the top of the CMakeLists.txt file found
115in the root of the AV1 repository, and AV1 codec configuration options can
116currently be found in the file `build/cmake/aom_config_defaults.cmake`.
117
118### Dylib builds {#dylib-builds}
119
120A dylib (shared object) build of the AV1 codec library can be enabled via the
121CMake built in variable `BUILD_SHARED_LIBS`:
122
123~~~
124 $ cmake path/to/aom -DBUILD_SHARED_LIBS=1
125 $ make
126~~~
127
128This is currently only supported on non-Windows targets.
129
130### Debugging {#debugging}
131
132Depending on the generator used there are multiple ways of going about
133debugging AV1 components. For single configuration generators like the Unix
134Makefiles generator, setting `CMAKE_BUILD_TYPE` to Debug is sufficient:
135
136~~~
137 $ cmake path/to/aom -DCMAKE_BUILD_TYPE=Debug
138~~~
139
140For Xcode, mainly because configuration controls for Xcode builds are buried two
141configuration windows deep and must be set for each subproject within the Xcode
142IDE individually, `CMAKE_CONFIGURATION_TYPES` should be set to Debug:
143
144~~~
145 $ cmake path/to/aom -G Xcode -DCMAKE_CONFIGURATION_TYPES=Debug
146~~~
147
148For Visual Studio the in-IDE configuration controls should be used. Simply set
149the IDE project configuration to Debug to allow for stepping through the code.
150
151In addition to the above it can sometimes be useful to debug only C and C++
152code. To disable all assembly code and intrinsics set `AOM_TARGET_CPU` to
153generic at generation time:
154
155~~~
156 $ cmake path/to/aom -DAOM_TARGET_CPU=generic
157~~~
158
159### Cross compiling {#cross-compiling}
160
161For the purposes of building the AV1 codec and applications and relative to the
162scope of this guide, all builds for architectures differing from the native host
163architecture will be considered cross compiles. The AV1 CMake build handles
164cross compiling via the use of toolchain files included in the AV1 repository.
165The toolchain files available at the time of this writing are:
166
167 - arm64-ios.cmake
168 - arm64-linux-clang.cmake
169 - arm64-linux-gcc.cmake
170 - arm64-mingw-gcc.cmake
171 - armv7-ios.cmake
172 - armv7-linux-gcc.cmake
173 - armv7-mingw-gcc.cmake
174 - armv7s-ios.cmake
175 - ppc-linux-gcc.cmake
176 - riscv-linux-gcc.cmake
177 - x86-ios-simulator.cmake
178 - x86-linux.cmake
179 - x86-macos.cmake
180 - x86-mingw-gcc.cmake
181 - x86\_64-ios-simulator.cmake
182 - x86\_64-mingw-gcc.cmake
183
184The following example demonstrates use of the x86-macos.cmake toolchain file on
185a x86\_64 MacOS host:
186
187~~~
188 $ cmake path/to/aom \
189 -DCMAKE_TOOLCHAIN_FILE=path/to/aom/build/cmake/toolchains/x86-macos.cmake
190 $ make
191~~~
192
193To build for an unlisted target creation of a new toolchain file is the best
194solution. The existing toolchain files can be used a starting point for a new
195toolchain file since each one exposes the basic requirements for toolchain files
196as used in the AV1 codec build.
197
198As a temporary work around an unoptimized AV1 configuration that builds only C
199and C++ sources can be produced using the following commands:
200
201~~~
202 $ cmake path/to/aom -DAOM_TARGET_CPU=generic
203 $ make
204~~~
205
206In addition to the above it's important to note that the toolchain files
207suffixed with gcc behave differently than the others. These toolchain files
208attempt to obey the $CROSS environment variable.
209
210### Sanitizers {#sanitizers}
211
212Sanitizer integration is built-in to the CMake build system. To enable a
213sanitizer, add `-DSANITIZE=<type>` to the CMake command line. For example, to
214enable address sanitizer:
215
216~~~
217 $ cmake path/to/aom -DSANITIZE=address
218 $ make
219~~~
220
221Sanitizers available vary by platform, target, and compiler. Consult your
222compiler documentation to determine which, if any, are available.
223
224### Microsoft Visual Studio builds {#microsoft-visual-studio-builds}
225
226Building the AV1 codec library in Microsoft Visual Studio is supported. Visual
227Studio 2019 (16.0) or later is required. The following example demonstrates
228generating projects and a solution for the Microsoft IDE:
229
230~~~
231 # This does not require a bash shell; Command Prompt (cmd.exe) is fine.
232 # This assumes the build host is a Windows x64 computer.
233
234 # To create a Visual Studio 2022 solution for the x64 target:
235 $ cmake path/to/aom -G "Visual Studio 17 2022"
236
237 # To create a Visual Studio 2022 solution for the 32-bit x86 target:
238 $ cmake path/to/aom -G "Visual Studio 17 2022" -A Win32
239
240 # To create a Visual Studio 2019 solution for the x64 target:
241 $ cmake path/to/aom -G "Visual Studio 16 2019"
242
243 # To create a Visual Studio 2019 solution for the 32-bit x86 target:
244 $ cmake path/to/aom -G "Visual Studio 16 2019" -A Win32
245
246 # To build the solution:
247 $ cmake --build .
248~~~
249
250NOTE: The build system targets Windows 7 or later by compiling files with
251`-D_WIN32_WINNT=0x0601`.
252
253### Xcode builds {#xcode-builds}
254
255Building the AV1 codec library in Xcode is supported. The following example
256demonstrates generating an Xcode project:
257
258~~~
259 $ cmake path/to/aom -G Xcode
260~~~
261
262### Emscripten builds {#emscripten-builds}
263
264Building the AV1 codec library with Emscripten is supported. Typically this is
265used to hook into the AOMAnalyzer GUI application. These instructions focus on
266using the inspector with AOMAnalyzer, but all tools can be built with
267Emscripten.
268
269It is assumed here that you have already downloaded and installed the EMSDK,
270installed and activated at least one toolchain, and setup your environment
271appropriately using the emsdk\_env script.
272
2731. Build [AOM Analyzer](https://github.com/xiph/aomanalyzer).
274
2752. Configure the build:
276
277~~~
278 $ cmake path/to/aom \
279 -DENABLE_CCACHE=1 \
280 -DAOM_TARGET_CPU=generic \
281 -DENABLE_DOCS=0 \
282 -DENABLE_TESTS=0 \
283 -DCONFIG_ACCOUNTING=1 \
284 -DCONFIG_INSPECTION=1 \
285 -DCONFIG_MULTITHREAD=0 \
286 -DCONFIG_RUNTIME_CPU_DETECT=0 \
287 -DCONFIG_WEBM_IO=0 \
288 -DCMAKE_TOOLCHAIN_FILE=path/to/emsdk-portable/.../Emscripten.cmake
289~~~
290
2913. Build it: run make if that's your generator of choice:
292
293~~~
294 $ make inspect
295~~~
296
2974. Run the analyzer:
298
299~~~
300 # inspect.js is in the examples sub directory of the directory in which you
301 # executed cmake.
302 $ path/to/AOMAnalyzer path/to/examples/inspect.js path/to/av1/input/file
303~~~
304
305### Extra build flags {#extra-build-flags}
306
307Three variables allow for passing of additional flags to the build system.
308
309- AOM\_EXTRA\_C\_FLAGS
310- AOM\_EXTRA\_CXX\_FLAGS
311- AOM\_EXTRA\_EXE\_LINKER\_FLAGS
312
313The build system attempts to ensure the flags passed through the above variables
314are passed to tools last in order to allow for override of default behavior.
315These flags can be used, for example, to enable asserts in a release build:
316
317~~~
318 $ cmake path/to/aom \
319 -DCMAKE_BUILD_TYPE=Release \
320 -DAOM_EXTRA_C_FLAGS=-UNDEBUG \
321 -DAOM_EXTRA_CXX_FLAGS=-UNDEBUG
322~~~
323
324### Build with VMAF support {#build-with-vmaf}
325
326After installing
327[libvmaf.a](https://github.com/Netflix/vmaf/tree/master/libvmaf),
328you can use it with the encoder:
329
330~~~
331 $ cmake path/to/aom -DCONFIG_TUNE_VMAF=1
332~~~
333
334Please note that the default VMAF model
335("/usr/local/share/model/vmaf_v0.6.1.json")
336will be used unless you set the following flag when running the encoder:
337
338~~~
339 # --vmaf-model-path=path/to/model
340~~~
341
342## Testing the AV1 codec {#testing-the-av1-codec}
343
344### Testing basics {#testing-basics}
345
346There are several methods of testing the AV1 codec. All of these methods require
347the presence of the AV1 source code and a working build of the AV1 library and
348applications.
349
350#### 1. Unit tests: {#unit-tests}
351
352The unit tests can be run at build time:
353
354~~~
355 # Before running the make command the LIBAOM_TEST_DATA_PATH environment
356 # variable should be set to avoid downloading the test files to the
357 # cmake build configuration directory.
358 $ cmake path/to/aom
359 # Note: The AV1 CMake build creates many test targets. Running make
360 # with multiple jobs will speed up the test run significantly.
361 $ make runtests
362~~~
363
364#### 2. Example tests: {#example-tests}
365
366The example tests require a bash shell and can be run in the following manner:
367
368~~~
369 # See the note above about LIBAOM_TEST_DATA_PATH above.
370 $ cmake path/to/aom
371 $ make
372 # It's best to build the testdata target using many make jobs.
373 # Running it like this will verify and download (if necessary)
374 # one at a time, which takes a while.
375 $ make testdata
376 $ path/to/aom/test/examples.sh --bin-path examples
377~~~
378
379#### 3. Encoder tests: {#encoder-tests}
380
381When making a change to the encoder run encoder tests to confirm that your
382change has a positive or negligible impact on encode quality. When running these
383tests the build configuration should be changed to enable internal encoder
384statistics:
385
386~~~
387 $ cmake path/to/aom -DCONFIG_INTERNAL_STATS=1
388 $ make
389~~~
390
391The repository contains scripts intended to make running these tests as simple
392as possible. The following example demonstrates creating a set of baseline clips
393for comparison to results produced after making your change to libaom:
394
395~~~
396 # This will encode all Y4M files in the current directory using the
397 # settings specified to create the encoder baseline statistical data:
398 $ cd path/to/test/inputs
399 # This command line assumes that run_encodes.sh, its helper script
400 # best_encode.sh, and the aomenc you intend to test are all within a
401 # directory in your PATH.
402 $ run_encodes.sh 200 500 50 baseline
403~~~
404
405After making your change and creating the baseline clips, you'll need to run
406encodes that include your change(s) to confirm that things are working as
407intended:
408
409~~~
410 # This will encode all Y4M files in the current directory using the
411 # settings specified to create the statistical data for your change:
412 $ cd path/to/test/inputs
413 # This command line assumes that run_encodes.sh, its helper script
414 # best_encode.sh, and the aomenc you intend to test are all within a
415 # directory in your PATH.
416 $ run_encodes.sh 200 500 50 mytweak
417~~~
418
419After creating both data sets you can use `test/visual_metrics.py` to generate a
420report that can be viewed in a web browser:
421
422~~~
423 $ visual_metrics.py metrics_template.html "*stt" baseline mytweak \
424 > mytweak.html
425~~~
426
427You can view the report by opening mytweak.html in a web browser.
428
429
430### IDE hosted tests {#ide-hosted-tests}
431
432By default the generated projects files created by CMake will not include the
433runtests and testdata rules when generating for IDEs like Microsoft Visual
434Studio and Xcode. This is done to avoid intolerably long build cycles in the
435IDEs-- IDE behavior is to build all targets when selecting the build project
436options in MSVS and Xcode. To enable the test rules in IDEs the
437`ENABLE_IDE_TEST_HOSTING` variable must be enabled at CMake generation time:
438
439~~~
440 # This example uses Xcode. To get a list of the generators
441 # available, run cmake with the -G argument missing its
442 # value.
443 $ cmake path/to/aom -DENABLE_IDE_TEST_HOSTING=1 -G Xcode
444~~~
445
446### Downloading the test data {#downloading-the-test-data}
447
448The fastest and easiest way to obtain the test data is to use CMake to generate
449a build using the Unix Makefiles generator, and then to build only the testdata
450rule. By default the test files will be downloaded to the current directory. The
451`LIBAOM_TEST_DATA_PATH` environment variable can be used to set a
452custom one.
453
454~~~
455 $ cmake path/to/aom -G "Unix Makefiles"
456 # 28 is used because there are 28 test files as of this writing.
457 $ make -j28 testdata
458~~~
459
460The above make command will only download and verify the test data.
461
462### Adding a new test data file {#adding-a-new-test-data-file}
463
464First, add the new test data file to the `aom-test-data` bucket of the
465`aomedia-testing` project on Google Cloud Platform. You may need to ask someone
466with the necessary access permissions to do this for you.
467
468NOTE: When a new test data file is added to the `aom-test-data` bucket, its
469"Public access" is initially "Not public". We need to change its
470"Public access" to "Public" by using the following
471[`gsutil`](https://cloud.google.com/storage/docs/gsutil_install) command:
472~~~
473 $ gsutil acl ch -g all:R gs://aom-test-data/test-data-file-name
474~~~
475This command grants the `AllUsers` group READ access to the file named
476"test-data-file-name" in the `aom-test-data` bucket.
477
478Once the new test data file has been added to `aom-test-data`, create a CL to
479add the name of the new test data file to `test/test_data_util.cmake` and add
480the SHA1 checksum of the new test data file to `test/test-data.sha1`. (The SHA1
481checksum of a file can be calculated by running the `sha1sum` command on the
482file.)
483
484### Additional test data {#additional-test-data}
485
486The test data mentioned above is strictly intended for unit testing.
487
488Additional input data for testing the encoder can be obtained from:
489https://media.xiph.org/video/derf/
490
491### Sharded testing {#sharded-testing}
492
493The AV1 codec library unit tests are built upon gtest which supports sharding of
494test jobs. Sharded test runs can be achieved in a couple of ways.
495
496#### 1. Running test\_libaom directly: {#running-test_libaom-directly}
497
498~~~
499 # Set the environment variable GTEST_TOTAL_SHARDS to control the number of
500 # shards.
501 $ export GTEST_TOTAL_SHARDS=10
502 # (GTEST shard indexing is 0 based).
503 $ seq 0 $(( $GTEST_TOTAL_SHARDS - 1 )) \
504 | xargs -n 1 -P 0 -I{} env GTEST_SHARD_INDEX={} ./test_libaom
505~~~
506
507To create a test shard for each CPU core available on the current system set
508`GTEST_TOTAL_SHARDS` to the number of CPU cores on your system minus one.
509
510#### 2. Running the tests via the CMake build: {#running-the-tests-via-the-cmake-build}
511
512~~~
513 # For IDE based builds, ENABLE_IDE_TEST_HOSTING must be enabled. See
514 # the IDE hosted tests section above for more information. If the IDE
515 # supports building targets concurrently tests will be sharded by default.
516
517 # For make and ninja builds the -j parameter controls the number of shards
518 # at test run time. This example will run the tests using 10 shards via
519 # make.
520 $ make -j10 runtests
521~~~
522
523The maximum number of test targets that can run concurrently is determined by
524the number of CPUs on the system where the build is configured as detected by
525CMake. A system with 24 cores can run 24 test shards using a value of 24 with
526the `-j` parameter. When CMake is unable to detect the number of cores 10 shards
527is the default maximum value.
528
529## Coding style {#coding-style}
530
531We are using the Google C Coding Style defined by the
532[Google C++ Style Guide](https://google.github.io/styleguide/cppguide.html).
533
534The coding style used by this project is enforced with clang-format using the
535configuration contained in the
536[.clang-format](https://chromium.googlesource.com/webm/aom/+/main/.clang-format)
537file in the root of the repository.
538
539You can download clang-format using your system's package manager, or directly
540from [llvm.org](http://llvm.org/releases/download.html). You can also view the
541[documentation](https://clang.llvm.org/docs/ClangFormat.html) on llvm.org.
542Output from clang-format varies by clang-format version, for best results your
543version should match the one used on Jenkins. You can find the clang-format
544version by reading the comment in the `.clang-format` file linked above.
545
546Before pushing changes for review you can format your code with:
547
548~~~
549 # Apply clang-format to modified .c, .h and .cc files
550 $ clang-format -i --style=file \
551 $(git diff --name-only --diff-filter=ACMR '*.[hc]' '*.cc')
552~~~
553
554Check the .clang-format file for the version used to generate it if there is any
555difference between your local formatting and the review system.
556
557Some Git installations have clang-format integration. Here are some examples:
558
559~~~
560 # Apply clang-format to all staged changes:
561 $ git clang-format
562
563 # Clang format all staged and unstaged changes:
564 $ git clang-format -f
565
566 # Clang format all staged and unstaged changes interactively:
567 $ git clang-format -f -p
568~~~
569
570## Submitting patches {#submitting-patches}
571
572We manage the submission of patches using the
573[Gerrit](https://www.gerritcodereview.com/) code review tool. This tool
574implements a workflow on top of the Git version control system to ensure that
575all changes get peer reviewed and tested prior to their distribution.
576
577### Login cookie {#login-cookie}
578
579Browse to [AOMedia Git index](https://aomedia.googlesource.com/) and login with
580your account (Gmail credentials, for example). Next, follow the
581`Generate Password` Password link at the top of the page. You’ll be given
582instructions for creating a cookie to use with our Git repos.
583
584You must also have a Gerrit account associated with your Google account. To do
585this visit the [Gerrit review server](https://aomedia-review.googlesource.com)
586and click "Sign in" (top right).
587
588### Contributor agreement {#contributor-agreement}
589
590You will be required to execute a
591[contributor agreement](http://aomedia.org/license) to ensure that the AOMedia
592Project has the right to distribute your changes.
593
594Note: If you are pushing changes on behalf of an Alliance for Open Media member
595organization this step is not necessary.
596
597### Testing your code {#testing-your-code}
598
599The testing basics are covered in the [testing section](#testing-the-av1-codec)
600above.
601
602In addition to the local tests, many more (e.g. asan, tsan, valgrind) will run
603through Jenkins instances upon upload to gerrit.
604
605### Commit message hook {#commit-message-hook}
606
607Gerrit requires that each submission include a unique Change-Id. You can assign
608one manually using git commit --amend, but it’s easier to automate it with the
609commit-msg hook provided by Gerrit.
610
611Copy commit-msg to the `.git/hooks` directory of your local repo. Here's an
612example:
613
614~~~
615 $ curl -Lo aom/.git/hooks/commit-msg https://chromium-review.googlesource.com/tools/hooks/commit-msg
616
617 # Next, ensure that the downloaded commit-msg script is executable:
618 $ chmod u+x aom/.git/hooks/commit-msg
619~~~
620
621See the Gerrit
622[documentation](https://gerrit-review.googlesource.com/Documentation/user-changeid.html)
623for more information.
624
625### Upload your change {#upload-your-change}
626
627The command line to upload your patch looks like this:
628
629~~~
630 $ git push https://aomedia-review.googlesource.com/aom HEAD:refs/for/main
631~~~
632
633### Incorporating reviewer comments {#incorporating-reviewer-comments}
634
635If you previously uploaded a change to Gerrit and the Approver has asked for
636changes, follow these steps:
637
6381. Edit the files to make the changes the reviewer has requested.
6392. Recommit your edits using the --amend flag, for example:
640
641~~~
642 $ git commit -a --amend
643~~~
644
6453. Use the same git push command as above to upload to Gerrit again for another
646 review cycle.
647
648In general, you should not rebase your changes when doing updates in response to
649review. Doing so can make it harder to follow the evolution of your change in
650the diff view.
651
652### Submitting your change {#submitting-your-change}
653
654Once your change has been Approved and Verified, you can “submit” it through the
655Gerrit UI. This will usually automatically rebase your change onto the branch
656specified.
657
658Sometimes this can’t be done automatically. If you run into this problem, you
659must rebase your changes manually:
660
661~~~
662 $ git fetch
663 $ git rebase origin/branchname
664~~~
665
666If there are any conflicts, resolve them as you normally would with Git. When
667you’re done, reupload your change.
668
669### Viewing the status of uploaded changes {#viewing-the-status-of-uploaded-changes}
670
671To check the status of a change that you uploaded, open
672[Gerrit](https://aomedia-review.googlesource.com/), sign in, and click My >
673Changes.
674
675## Support {#support}
676
677This library is an open source project supported by its community. Please
678please email aomediacodec@jointdevelopment.kavi.com for help.
679
680## Bug reports {#bug-reports}
681
682Bug reports can be filed in the Alliance for Open Media
683[issue tracker](https://bugs.chromium.org/p/aomedia/issues/list).
684