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# ExoPlayer AV1 extension #
The AV1 extension provides `Libgav1VideoRenderer`, which uses libgav1 native
library to decode AV1 videos.
## License note ##
Please note that whilst the code in this repository is licensed under
[Apache 2.0][], using this extension also requires building and including one or
more external libraries as described below. These are licensed separately.
[Apache 2.0]: https://github.com/google/ExoPlayer/blob/release-v2/LICENSE
## Build instructions (Linux, macOS) ##
To use this extension you need to clone the ExoPlayer repository and depend on
its modules locally. Instructions for doing this can be found in ExoPlayer's
[top level README][].
In addition, it's necessary to fetch cpu_features library and libgav1 with its
dependencies as follows:
* Set the following environment variables:
```
cd "<path to exoplayer checkout>"
EXOPLAYER_ROOT="$(pwd)"
AV1_EXT_PATH="${EXOPLAYER_ROOT}/extensions/av1/src/main"
```
* Fetch cpu_features library:
```
cd "${AV1_EXT_PATH}/jni" && \
git clone https://github.com/google/cpu_features
```
* Fetch libgav1:
```
cd "${AV1_EXT_PATH}/jni" && \
git clone https://chromium.googlesource.com/codecs/libgav1 libgav1
```
* Fetch Abseil:
```
cd "${AV1_EXT_PATH}/jni/libgav1" && \
git clone https://github.com/abseil/abseil-cpp.git third_party/abseil-cpp
```
* [Install CMake][].
Having followed these steps, gradle will build the extension automatically when
run on the command line or via Android Studio, using [CMake][] and [Ninja][]
to configure and build libgav1 and the extension's [JNI wrapper library][].
[top level README]: https://github.com/google/ExoPlayer/blob/release-v2/README.md
[Install CMake]: https://developer.android.com/studio/projects/install-ndk
[CMake]: https://cmake.org/
[Ninja]: https://ninja-build.org
[JNI wrapper library]: https://github.com/google/ExoPlayer/blob/release-v2/extensions/av1/src/main/jni/gav1_jni.cc
## Build instructions (Windows) ##
We do not provide support for building this extension on Windows, however it
should be possible to follow the Linux instructions in [Windows PowerShell][].
[Windows PowerShell]: https://docs.microsoft.com/en-us/powershell/scripting/getting-started/getting-started-with-windows-powershell
## Using the extension ##
Once you've followed the instructions above to check out, build and depend on
the extension, the next step is to tell ExoPlayer to use `Libgav1VideoRenderer`.
How you do this depends on which player API you're using:
* If you're passing a `DefaultRenderersFactory` to `SimpleExoPlayer.Builder`,
you can enable using the extension by setting the `extensionRendererMode`
parameter of the `DefaultRenderersFactory` constructor to
`EXTENSION_RENDERER_MODE_ON`. This will use `Libgav1VideoRenderer` for
playback if `MediaCodecVideoRenderer` doesn't support decoding the input AV1
stream. Pass `EXTENSION_RENDERER_MODE_PREFER` to give `Libgav1VideoRenderer`
priority over `MediaCodecVideoRenderer`.
* If you've subclassed `DefaultRenderersFactory`, add a `Libvgav1VideoRenderer`
to the output list in `buildVideoRenderers`. ExoPlayer will use the first
`Renderer` in the list that supports the input media format.
* If you've implemented your own `RenderersFactory`, return a
`Libgav1VideoRenderer` instance from `createRenderers`. ExoPlayer will use the
first `Renderer` in the returned array that supports the input media format.
* If you're using `ExoPlayer.Builder`, pass a `Libgav1VideoRenderer` in the
array of `Renderer`s. ExoPlayer will use the first `Renderer` in the list that
supports the input media format.
Note: These instructions assume you're using `DefaultTrackSelector`. If you have
a custom track selector the choice of `Renderer` is up to your implementation.
You need to make sure you are passing a `Libgav1VideoRenderer` to the player and
then you need to implement your own logic to use the renderer for a given track.
## Using the extension in the demo application ##
To try out playback using the extension in the [demo application][], see
[enabling extension decoders][].
[demo application]: https://exoplayer.dev/demo-application.html
[enabling extension decoders]: https://exoplayer.dev/demo-application.html#enabling-extension-decoders
## Rendering options ##
There are two possibilities for rendering the output `Libgav1VideoRenderer`
gets from the libgav1 decoder:
* GL rendering using GL shader for color space conversion
* If you are using `SimpleExoPlayer` with `PlayerView`, enable this option by
setting `surface_type` of `PlayerView` to be
`video_decoder_gl_surface_view`.
* Otherwise, enable this option by sending `Libgav1VideoRenderer` a message
of type `C.MSG_SET_VIDEO_DECODER_OUTPUT_BUFFER_RENDERER` with an instance of
`VideoDecoderOutputBufferRenderer` as its object.
* Native rendering using `ANativeWindow`
* If you are using `SimpleExoPlayer` with `PlayerView`, this option is enabled
by default.
* Otherwise, enable this option by sending `Libgav1VideoRenderer` a message of
type `C.MSG_SET_SURFACE` with an instance of `SurfaceView` as its object.
Note: Although the default option uses `ANativeWindow`, based on our testing the
GL rendering mode has better performance, so should be preferred
## Links ##
* [Javadoc][]: Classes matching `com.google.android.exoplayer2.ext.av1.*`
belong to this module.
[Javadoc]: https://exoplayer.dev/doc/reference/index.html