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104 lines
4.0 KiB
Markdown
104 lines
4.0 KiB
Markdown
# Flac decoder module
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The Flac module provides `FlacExtractor` and `LibflacAudioRenderer`, which use
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libFLAC (the Flac decoding library) to extract and decode FLAC audio.
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## License note
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Please note that whilst the code in this repository is licensed under
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[Apache 2.0][], using this module also requires building and including one or
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more external libraries as described below. These are licensed separately.
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[Apache 2.0]: ../../LICENSE
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## Build instructions (Linux, macOS)
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To use the module you need to clone this GitHub project and depend on its
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modules locally. Instructions for doing this can be found in the
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[top level README][].
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In addition, it's necessary to build the module's native components as follows:
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* Set the following environment variables:
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```
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cd "<path to project checkout>"
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FLAC_MODULE_PATH="$(pwd)/libraries/decoder_flac/src/main"
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```
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* Download the [Android NDK][] and set its location in an environment variable.
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This build configuration has been tested on NDK r21.
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```
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NDK_PATH="<path to Android NDK>"
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```
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* Download and extract flac-1.3.2 as "${FLAC_MODULE_PATH}/jni/flac" folder:
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```
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cd "${FLAC_MODULE_PATH}/jni" && \
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curl https://ftp.osuosl.org/pub/xiph/releases/flac/flac-1.3.2.tar.xz | tar xJ && \
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mv flac-1.3.2 flac
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```
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* Build the JNI native libraries from the command line:
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```
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cd "${FLAC_MODULE_PATH}"/jni && \
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${NDK_PATH}/ndk-build APP_ABI=all -j4
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```
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[top level README]: ../../README.md
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[Android NDK]: https://developer.android.com/tools/sdk/ndk/index.html
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## Build instructions (Windows)
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We do not provide support for building this module on Windows, however it should
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be possible to follow the Linux instructions in [Windows PowerShell][].
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[Windows PowerShell]: https://docs.microsoft.com/en-us/powershell/scripting/getting-started/getting-started-with-windows-powershell
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## Using the module
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Once you've followed the instructions above to check out, build and depend on
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the module, the next step is to tell ExoPlayer to use the extractor and/or
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renderer.
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### Using `FlacExtractor`
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`FlacExtractor` is used via `ProgressiveMediaSource`. If you're using
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`DefaultExtractorsFactory`, `FlacExtractor` will automatically be used to read
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`.flac` files. If you're not using `DefaultExtractorsFactory`, return a
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`FlacExtractor` from your `ExtractorsFactory.createExtractors` implementation.
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### Using `LibflacAudioRenderer` with ExoPlayer
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* If you're passing a `DefaultRenderersFactory` to `ExoPlayer.Builder`, you
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can enable using the module by setting the `extensionRendererMode` parameter
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of the `DefaultRenderersFactory` constructor to
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`EXTENSION_RENDERER_MODE_ON`. This will use `LibflacAudioRenderer` for
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playback if `MediaCodecAudioRenderer` doesn't support the input format. Pass
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`EXTENSION_RENDERER_MODE_PREFER` to give `LibflacAudioRenderer` priority
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over `MediaCodecAudioRenderer`.
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* If you've subclassed `DefaultRenderersFactory`, add a `LibflacAudioRenderer`
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to the output list in `buildAudioRenderers`. ExoPlayer will use the first
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`Renderer` in the list that supports the input media format.
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* If you've implemented your own `RenderersFactory`, return a
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`LibflacAudioRenderer` instance from `createRenderers`. ExoPlayer will use
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the first `Renderer` in the returned array that supports the input media
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format.
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* If you're using `ExoPlayer.Builder`, pass a `LibflacAudioRenderer` in the
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array of `Renderer`s. ExoPlayer will use the first `Renderer` in the list
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that supports the input media format.
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Note: These instructions assume you're using `DefaultTrackSelector`. If you have
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a custom track selector the choice of `Renderer` is up to your implementation,
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so you need to make sure you are passing an `LibflacAudioRenderer` to the
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player, then implement your own logic to use the renderer for a given track.
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## Links
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* [Troubleshooting using decoding extensions][]
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[Troubleshooting using decoding extensions]: https://developer.android.com/guide/topics/media/exoplayer/troubleshooting#how-can-i-get-a-decoding-library-to-load-and-be-used-for-playback
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