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0d86f4475c
Currently FlacDecoder/FlacExtractor always perform resampling to 16bit. In some case (with 24bit audio), this might lower the audio quality if the system supports 24bit audio. Since AudioTrack implementation supports resampling, we will remove the resampling step, and return an output with the same bits-per-sample as the original stream. User can choose to re-sample to 16bit in AudioTrack if necessary. ------------- Created by MOE: https://github.com/google/moe MOE_MIGRATED_REVID=167494350
98 lines
3.7 KiB
Markdown
98 lines
3.7 KiB
Markdown
# ExoPlayer Flac extension #
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The Flac extension provides `FlacExtractor` and `LibflacAudioRenderer`, which
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use 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 extension 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]: https://github.com/google/ExoPlayer/blob/release-v2/LICENSE
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## Build instructions ##
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To use this extension you need to clone the ExoPlayer repository and depend on
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its modules locally. Instructions for doing this can be found in ExoPlayer's
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[top level README][].
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In addition, it's necessary to build the extension's native components as
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follows:
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* Set the following environment variables:
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```
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cd "<path to exoplayer checkout>"
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EXOPLAYER_ROOT="$(pwd)"
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FLAC_EXT_PATH="${EXOPLAYER_ROOT}/extensions/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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```
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NDK_PATH="<path to Android NDK>"
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```
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* Download and extract flac-1.3.1 as "${FLAC_EXT_PATH}/jni/flac" folder:
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```
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cd "${FLAC_EXT_PATH}/jni" && \
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curl https://ftp.osuosl.org/pub/xiph/releases/flac/flac-1.3.1.tar.xz | tar xJ && \
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mv flac-1.3.1 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 "${FLAC_EXT_PATH}"/jni && \
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${NDK_PATH}/ndk-build APP_ABI=all -j4
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```
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[top level README]: https://github.com/google/ExoPlayer/blob/release-v2/README.md
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[Android NDK]: https://developer.android.com/tools/sdk/ndk/index.html
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## Using the extension ##
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Once you've followed the instructions above to check out, build and depend on
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the extension, 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 `ExtractorMediaSource`. 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` ###
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* If you're passing a `DefaultRenderersFactory` to
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`ExoPlayerFactory.newSimpleInstance`, you can enable using the extension by
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setting the `extensionRendererMode` parameter of the `DefaultRenderersFactory`
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constructor to `EXTENSION_RENDERER_MODE_ON`. This will use
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`LibflacAudioRenderer` for playback if `MediaCodecAudioRenderer` doesn't
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support the input format. Pass `EXTENSION_RENDERER_MODE_PREFER` to give
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`LibflacAudioRenderer` priority 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 the
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first `Renderer` in the returned array that supports the input media format.
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* If you're using `ExoPlayerFactory.newInstance`, pass a `LibflacAudioRenderer`
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in the array of `Renderer`s. ExoPlayer will use the first `Renderer` in the
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list 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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* [Javadoc][]: Classes matching `com.google.android.exoplayer2.ext.flac.*`
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belong to this module.
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[Javadoc]: https://google.github.io/ExoPlayer/doc/reference/index.html
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