media3/extensions/vp9/README.md
2018-01-15 14:13:30 +00:00

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# ExoPlayer VP9 extension #
The VP9 extension provides `LibvpxVideoRenderer`, which uses libvpx (the VPx
decoding library) to decode VP9 video.
## 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 ##
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 build the extension's native components as
follows:
* Set the following environment variables:
```
cd "<path to exoplayer checkout>"
EXOPLAYER_ROOT="$(pwd)"
VP9_EXT_PATH="${EXOPLAYER_ROOT}/extensions/vp9/src/main"
```
* Download the [Android NDK][] and set its location in an environment variable.
```
NDK_PATH="<path to Android NDK>"
```
* Fetch libvpx and libyuv:
```
cd "${VP9_EXT_PATH}/jni" && \
git clone https://chromium.googlesource.com/webm/libvpx libvpx && \
git clone https://chromium.googlesource.com/libyuv/libyuv libyuv
```
* Checkout the appropriate branches of libvpx and libyuv (the scripts and
makefiles bundled in this repo are known to work only at these versions of the
libraries - we will update this periodically as newer versions of
libvpx/libyuv are released):
```
cd "${VP9_EXT_PATH}/jni/libvpx" && \
git checkout tags/v1.6.1 -b v1.6.1 && \
cd "${VP9_EXT_PATH}/jni/libyuv" && \
git checkout 996a2bbd
```
* Run a script that generates necessary configuration files for libvpx:
```
cd ${VP9_EXT_PATH}/jni && \
./generate_libvpx_android_configs.sh "${NDK_PATH}"
```
* Build the JNI native libraries from the command line:
```
cd "${VP9_EXT_PATH}"/jni && \
${NDK_PATH}/ndk-build APP_ABI=all -j4
```
[top level README]: https://github.com/google/ExoPlayer/blob/release-v2/README.md
[Android NDK]: https://developer.android.com/tools/sdk/ndk/index.html
[#3520]: https://github.com/google/ExoPlayer/issues/3520
## Notes ##
* Every time there is a change to the libvpx checkout:
* Android config scripts should be re-generated by running
`generate_libvpx_android_configs.sh`
* Clean and re-build the project.
* If you want to use your own version of libvpx or libyuv, place it in
`${VP9_EXT_PATH}/jni/libvpx` or `${VP9_EXT_PATH}/jni/libyuv` respectively. But
please note that `generate_libvpx_android_configs.sh` and the makefiles need
to be modified to work with arbitrary versions of libvpx and libyuv.
## 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 `LibvpxVideoRenderer`.
How you do this depends on which player API you're using:
* If you're passing a `DefaultRenderersFactory` to
`ExoPlayerFactory.newSimpleInstance`, you can enable using the extension by
setting the `extensionRendererMode` parameter of the `DefaultRenderersFactory`
constructor to `EXTENSION_RENDERER_MODE_ON`. This will use
`LibvpxVideoRenderer` for playback if `MediaCodecVideoRenderer` doesn't
support decoding the input VP9 stream. Pass `EXTENSION_RENDERER_MODE_PREFER`
to give `LibvpxVideoRenderer` priority over `MediaCodecVideoRenderer`.
* If you've subclassed `DefaultRenderersFactory`, add a `LibvpxVideoRenderer`
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
`LibvpxVideoRenderer` instance from `createRenderers`. ExoPlayer will use the
first `Renderer` in the returned array that supports the input media format.
* If you're using `ExoPlayerFactory.newInstance`, pass a `LibvpxVideoRenderer`
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,
so you need to make sure you are passing an `LibvpxVideoRenderer` to the
player, then implement your own logic to use the renderer for a given track.
`LibvpxVideoRenderer` can optionally output to a `VpxVideoSurfaceView` when not
being used via `SimpleExoPlayer`, in which case color space conversion will be
performed using a GL shader. To enable this mode, send the renderer a message of
type `LibvpxVideoRenderer.MSG_SET_OUTPUT_BUFFER_RENDERER` with the
`VpxVideoSurfaceView` as its object, instead of sending `MSG_SET_SURFACE` with a
`Surface`.
## Links ##
* [Javadoc][]: Classes matching `com.google.android.exoplayer2.ext.vp9.*`
belong to this module.
[Javadoc]: https://google.github.io/ExoPlayer/doc/reference/index.html