Opus decoder module

The Opus module provides LibopusAudioRenderer, which uses the libopus native 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.

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 fetch libopus as follows:

• Set the following environment variables:

cd "<path to project checkout>"
OPUS_MODULE_PATH="$(pwd)/libraries/decoder_opus/src/main"

• Fetch libopus:

cd "${OPUS_MODULE_PATH}/jni" && \
git clone https://gitlab.xiph.org/xiph/opus.git libopus

• Install CMake

Having followed these steps, gradle will build the module automatically when run on the command line or via Android Studio, using CMake and Ninja to configure and build libopus and the module's JNI wrapper library.

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.

Using the module with ExoPlayer

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 Renderers. 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.

Links

• Troubleshooting using decoding extensions