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media/libraries/decoder_flac
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ibaker 5c1e0d964a Add 32-bit FLAC test files, and use them in some tests 
The matroska file works without further changes. The FLAC container
file works with `lib-flac-decoder` depending on a bundled `libflac`
implementation, but not when using
`androidx.media3.extractor.flac.FlacExtractor` with a `MediaCodec` FLAC
decoder because the media3 extractor doesn't support 32-bit FLAC yet.
The fix for that is in a follow-up change.

`bear_32bit.flac` was generated from `bear.flac` with `ffmpeg`:

```shell
$ ffmpeg \
    -i bear.flac \
    -c:a flac \
    -sample_fmt s32 \
    -strict experimental \
    bear_32bit.flac
```

`bear-flac-32bit.mka` was generated by re-muxing `bear_32bit.flac`,
also with `ffmpeg` (trying to convert `bear-flac-24bit.mka` to 32-bit
didn't work, the resulting file was still 24-bit):

```shell
$ ffmpeg \
    -i ../flac/bear_32bit.flac \
    -c:a copy \
    bear-flac-32bit.mka
```

Issue: androidx/media#2197
PiperOrigin-RevId: 736552251
(cherry picked from commit dfebe72b6a175ed92420c1946bd06b952d85132d)
2025-03-18 11:39:46 +00:00
..
src
Add 32-bit FLAC test files, and use them in some tests
2025-03-18 11:39:46 +00:00
build.gradle
Switch most intra-lib deps from implementation to api
2025-02-12 11:29:50 -08:00
proguard-rules.txt
Update to androidx.media3
2021-10-27 09:12:46 +01:00
README.md
Simplify Flac extension build process
2024-10-11 03:09:32 -07:00

README.md

Flac decoder module

The Flac module provides FlacExtractor and LibflacAudioRenderer, which use libFLAC (the Flac decoding library) to extract and decode FLAC 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.

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 libflac as follows:

  • Set the following environment variables:
cd "<path to project checkout>"
FLAC_MODULE_PATH="$(pwd)/libraries/decoder_flac/src/main"
  • Fetch libflac:
cd "${FLAC_MODULE_PATH}/jni" && \
git clone https://github.com/xiph/flac.git libflac

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 libflac 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

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 the extractor and/or renderer.

Using FlacExtractor

FlacExtractor is used via ProgressiveMediaSource. If you're using DefaultExtractorsFactory, FlacExtractor will automatically be used to read .flac files. If you're not using DefaultExtractorsFactory, return a FlacExtractor from your ExtractorsFactory.createExtractors implementation.

Using LibflacAudioRenderer with ExoPlayer

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

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