media/libraries/decoder_mpegh/README.md

MPEG-H decoder module

The MPEG-H module provides MpeghAudioRenderer, which uses the libmpegh native library to decode MPEG-H audio.

License note

Please note that while the code in this repository is licensed under Apache 2.0, using this module also requires building and including the Fraunhofer GitHub MPEG-H decoder which is licensed under the Fraunhofer GitHub MPEG-H decoder project.

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 libmpegh library as follows:

• Set the following environment variables:

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

• Fetch libmpegh library:

cd "${MPEGH_MODULE_PATH}/jni" && \
git clone https://github.com/Fraunhofer-IIS/mpeghdec.git --branch r2.0.0 libmpegh

• 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 mpeghdec 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 MpeghAudioRenderer. 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 MpeghAudioRenderer for playback if MediaCodecAudioRenderer doesn't support the input format. Pass EXTENSION_RENDERER_MODE_PREFER to give MpeghAudioRenderer priority over MediaCodecAudioRenderer.
• If you've subclassed DefaultRenderersFactory, add a MpeghAudioRenderer 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 MpeghAudioRenderer 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 MpeghAudioRenderer 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 MpeghAudioRenderer to the player, then implement your own logic to use the renderer for a given track.

Links

• Troubleshooting using decoding extensions