rohks 6acddfeee6 Simplify IAMF extension build process
Removed `Android.mk` and `Application.mk`, allowing `CMake` to run directly from the `build.gradle` file. Users no longer need to check out `NDK` or depend on it, simplifying the usage of the IAMF extension.

PiperOrigin-RevId: 684471874
2024-10-10 09:32:25 -07:00

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# IAMF decoder module
The IAMF module provides `LibiamfAudioRenderer`, which uses the libiamf native
library to decode IAMF 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]: ../../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 fetch libiamf as follows:
* Set the following environment variables:
```
cd "<path to project checkout>"
IAMF_MODULE_PATH="$(pwd)/libraries/decoder_iamf/src/main"
```
* Fetch libiamf:
```
cd "${IAMF_MODULE_PATH}/jni" && \
git clone https://github.com/AOMediaCodec/libiamf.git
```
* [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 libiamf and the module's [JNI wrapper library][].
[top level README]: ../../README.md
[Install CMake]: https://developer.android.com/studio/projects/install-ndk
[CMake]: https://cmake.org/
[Ninja]: https://ninja-build.org
[JNI wrapper library]: src/main/jni/iamf_jni.cc
## 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
## 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 `LibiamfAudioRenderer`.
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 `LibiamfAudioRenderer` for
playback if `MediaCodecAudioRenderer` doesn't support the input format. Pass
`EXTENSION_RENDERER_MODE_PREFER` to give `LibiamfAudioRenderer` priority
over `MediaCodecAudioRenderer`.
* If you've subclassed `DefaultRenderersFactory`, add a `LibiamfAudioRenderer`
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
`LibiamfAudioRenderer` 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 `LibiamfAudioRenderer` 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 a `LibiamfAudioRenderer` to the
player, then implement your own logic to use the renderer for a given track.
## Links
* [Troubleshooting using decoding extensions][]
[Troubleshooting using decoding extensions]: https://developer.android.com/media/media3/exoplayer/troubleshooting#how-can-i-get-a-decoding-library-to-load-and-be-used-for-playback