android13/external/exoplayer/tree_15dc86382f17a24a3e881e.../extensions/opus/README.md

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# ExoPlayer Opus module
The Opus module provides `LibopusAudioRenderer`, which uses libopus (the Opus
decoding library) to decode Opus audio.
## License note
Please note that whilst the code in this repository is licensed under
[Apache 2.0][], using this module 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 the module you need to clone this GitHub project and depend on its
modules locally. Instructions for doing this can be found in the
[top level README][].
In addition, it's necessary to build the module's native components as follows:
* Set the following environment variables:
```
cd "<path to project checkout>"
OPUS_MODULE_PATH="$(pwd)/extensions/opus/src/main"
```
* Download the [Android NDK][] and set its location in an environment variable.
This build configuration has been tested on NDK r21.
```
NDK_PATH="<path to Android NDK>"
```
* Fetch libopus:
```
cd "${OPUS_MODULE_PATH}/jni" && \
git clone https://gitlab.xiph.org/xiph/opus.git libopus
```
* Run the script to convert arm assembly to NDK compatible format:
```
cd ${OPUS_MODULE_PATH}/jni && ./convert_android_asm.sh
```
* Build the JNI native libraries from the command line:
```
cd "${OPUS_MODULE_PATH}"/jni && \
${NDK_PATH}/ndk-build APP_ABI=all -j4
```
[top level README]: https://github.com/google/ExoPlayer/blob/release-v2/README.md
[Android NDK]: https://developer.android.com/tools/sdk/ndk/index.html
## Build instructions (Windows)
We do not provide support for building this module on Windows, however it should
be possible to follow the Linux instructions in [Windows PowerShell][].
[Windows PowerShell]: https://docs.microsoft.com/en-us/powershell/scripting/getting-started/getting-started-with-windows-powershell
## Notes
* Every time there is a change to the libopus checkout:
* Arm assembly should be converted by running `convert_android_asm.sh`
* Clean and re-build the project.
* If you want to use your own version of libopus, place it in
`${OPUS_MODULE_PATH}/jni/libopus`.
## Using the module
Once you've followed the instructions above to check out, build and depend on
the module, the next step is to tell ExoPlayer to use `LibopusAudioRenderer`.
How you do this depends on which player API you're using:
* If you're passing a `DefaultRenderersFactory` to `ExoPlayer.Builder`, you
can enable using the module by setting the `extensionRendererMode` parameter
of the `DefaultRenderersFactory` constructor to
`EXTENSION_RENDERER_MODE_ON`. This will use `LibopusAudioRenderer` for
playback if `MediaCodecAudioRenderer` doesn't support the input format. Pass
`EXTENSION_RENDERER_MODE_PREFER` to give `LibopusAudioRenderer` priority
over `MediaCodecAudioRenderer`.
* If you've subclassed `DefaultRenderersFactory`, add a `LibopusAudioRenderer`
to the output list in `buildAudioRenderers`. ExoPlayer will use the first
`Renderer` in the list that supports the input media format.
* If you've implemented your own `RenderersFactory`, return a
`LibopusAudioRenderer` 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 `LibopusAudioRenderer` 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 `LibopusAudioRenderer` to the
player, then implement your own logic to use the renderer for a given track.
## Using the module in the demo application
To try out playback using the module 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
## Links
* [Javadoc][]
[Javadoc]: https://exoplayer.dev/doc/reference/index.html