Add README.md.
And mark README as deprecated.
Change-Id: I9b353f70de9261a1877e520928df30b42226c02f
diff --git a/README.md b/README.md
new file mode 100644
index 0000000..1fc764d
--- /dev/null
+++ b/README.md
@@ -0,0 +1,189 @@
+# AV1 Codec Library
+
+## 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).
+
+### 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 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`.
+
+### 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
+ - 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.
+
+### 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
+
+
+## Testing the AV1 codec
+
+### Testing basics
+
+Currently there are two types of tests in the AV1 codec repository:
+
+ 1. Unit tests.
+ 2. 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
+
+### 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.
+
+
+## Coding style
+
+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
+
+## 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).
