android13/external/exoplayer/tree_8e57d3715f9092d5ec54eb.../extensions/ffmpeg/README.md

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# ExoPlayer FFmpeg module
The FFmpeg module provides `FfmpegAudioRenderer`, which uses FFmpeg for decoding
and can render audio encoded in a variety of formats.
## 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][]. The module is not provided via Google's Maven repository
(see [#2781][] for more information).
In addition, it's necessary to manually build the FFmpeg library, so that gradle
can bundle the FFmpeg binaries in the APK:
* Set the following shell variable:
```
cd "<path to project checkout>"
FFMPEG_MODULE_PATH="$(pwd)/extensions/ffmpeg/src/main"
```
* Download the [Android NDK][] and set its location in a shell variable.
This build configuration has been tested on NDK r21.
```
NDK_PATH="<path to Android NDK>"
```
* Set the host platform (use "darwin-x86_64" for Mac OS X):
```
HOST_PLATFORM="linux-x86_64"
```
* Fetch FFmpeg and checkout an appropriate branch. We cannot guarantee
compatibility with all versions of FFmpeg. We currently recommend version 4.2:
```
cd "<preferred location for ffmpeg>" && \
git clone git://source.ffmpeg.org/ffmpeg && \
cd ffmpeg && \
git checkout release/4.2 && \
FFMPEG_PATH="$(pwd)"
```
* Configure the decoders to include. See the [Supported formats][] page for
details of the available decoders, and which formats they support.
```
ENABLED_DECODERS=(vorbis opus flac)
```
* Add a link to the FFmpeg source code in the FFmpeg module `jni` directory.
```
cd "${FFMPEG_MODULE_PATH}/jni" && \
ln -s "$FFMPEG_PATH" ffmpeg
```
* Execute `build_ffmpeg.sh` to build FFmpeg for `armeabi-v7a`, `arm64-v8a`,
`x86` and `x86_64`. The script can be edited if you need to build for
different architectures:
```
cd "${FFMPEG_MODULE_PATH}/jni" && \
./build_ffmpeg.sh \
"${FFMPEG_MODULE_PATH}" "${NDK_PATH}" "${HOST_PLATFORM}" "${ENABLED_DECODERS[@]}"
```
## 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
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 `FfmpegAudioRenderer`. 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 `FfmpegAudioRenderer` for
playback if `MediaCodecAudioRenderer` doesn't support the input format. Pass
`EXTENSION_RENDERER_MODE_PREFER` to give `FfmpegAudioRenderer` priority over
`MediaCodecAudioRenderer`.
* If you've subclassed `DefaultRenderersFactory`, add an `FfmpegAudioRenderer`
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 an
`FfmpegAudioRenderer` 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 an `FfmpegAudioRenderer` 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 `FfmpegAudioRenderer` to the player,
then implement your own logic to use the renderer for a given track.
[top level README]: https://github.com/google/ExoPlayer/blob/release-v2/README.md
[Android NDK]: https://developer.android.com/tools/sdk/ndk/index.html
[#2781]: https://github.com/google/ExoPlayer/issues/2781
[Supported formats]: https://exoplayer.dev/supported-formats.html#ffmpeg-extension
## 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
* [Troubleshooting using extensions][]
* [Javadoc][]
[Troubleshooting using extensions]: https://exoplayer.dev/troubleshooting.html#how-can-i-get-a-decoding-extension-to-load-and-be-used-for-playback
[Javadoc]: https://exoplayer.dev/doc/reference/index.html