LFI Sandboxing for Android Media

This fork contains modified versions of the Opus and VP9 ExoPlayer decoders so that they can run in an app inside of an LFI sandbox.

These instructions will tell you how to set up the Opus sandboxed decoder for use with an app that uses ExoPlayer, such as OpusDemo. If you use the OpusDemo repository, make sure to change the last line of settings.gradle.kts to point to your checkout of this repository (pointing to core_settings.gradle).

Build

First, you'll need latest lfi-bind installed from the new-tls branch. Next, you'll need liblfi built from the new-tls branch of the main lfi repository and you need it to be built for Android. To cross-compile liblfi, first create a cross file (there is an example one for android in toolchains/android.txt that uses my local NDK compiler).

meson setup build-android --cross-file toolchains/android.txt
cd build-android
ninja liblfi/liblfi.a

Next, you'll have to place this library somewhere it can be found by your NDK build. As a quick solution, on my machine I placed it in my NDK sysroot: Android/Sdk/ndk/27.0.12077973/toolchains/llvm/prebuilt/linux-x86_64/sysroot/usr/lib/aarch64-linux-android/. There might be better locations, or it's probably possible to modify the CMake file (libraries/decoder_opus/src/main/jni/CMakeLists.txt) so that it can pick it up locally.

Now you can build the sandboxed libopus:

cd libraries/decoder_opus/src/main/jni
git clone https://gitlab.xiph.org/xiph/opus.git libopus
make LFICC=... -B

This should build libopus with the provided LFI compiler. By default it will use aarch64-lfi-linux-musl-clang. This will also generate the trampolines in gen/ with the lfi-bind command.

Once complete, you can include the Opus decoder from an app like the OpusDemo app.

AndroidX Media

AndroidX Media is a collection of libraries for implementing media use cases on Android, including local playback (via ExoPlayer), video editing (via Transformer) and media sessions.

Documentation

• The developer guide provides a wealth of information.
• The class reference documents the classes and methods.
• The release notes document the major changes in each release.
• The media dev center provides samples and guidelines.
• Follow our developer blog to keep up to date with the latest developments!

Migration for existing ExoPlayer and MediaSession projects

You'll find a migration guide for existing ExoPlayer and MediaSession users on developer.android.com.

API stability

AndroidX Media releases provide API stability guarantees, ensuring that the API surface remains backwards compatible for the most commonly used APIs. APIs intended for more advanced use cases are marked as unstable. To use an unstable method or class without lint warnings, you’ll need to add the OptIn annotation before using it. For more information see the UnstableApi documentation.

Using the libraries

You can get the libraries from the Google Maven repository. It's also possible to clone this GitHub repository and depend on the modules locally.

From the Google Maven repository

1. Add module dependencies

The easiest way to get started using AndroidX Media is to add gradle dependencies on the libraries you need in the build.gradle.kts file of your app module.

For example, to depend on ExoPlayer with DASH playback support and UI components you can add dependencies on the modules like this:

implementation("androidx.media3:media3-exoplayer:1.X.X")
implementation("androidx.media3:media3-exoplayer-dash:1.X.X")
implementation("androidx.media3:media3-ui:1.X.X")

Or in Gradle Groovy DSL build.gradle:

implementation 'androidx.media3:media3-exoplayer:1.X.X'
implementation 'androidx.media3:media3-exoplayer-dash:1.X.X'
implementation 'androidx.media3:media3-ui:1.X.X'

where 1.X.X is your preferred version. All modules must be the same version.

Please see the AndroidX Media3 developer.android.com page for more information, including a full list of library modules.

This repository includes some modules that depend on external libraries that need to be built manually, and are not available from the Maven repository. Please see the individual READMEs under the libraries directory for more details.

2. Turn on Java 8 support

If not enabled already, you also need to turn on Java 8 support in all build.gradle.kts files depending on AndroidX Media, by adding the following to the android section:

compileOptions {
  targetCompatibility = JavaVersion.VERSION_1_8
}

Or in Gradle Groovy DSL build.gradle:

compileOptions {
  targetCompatibility JavaVersion.VERSION_1_8
}

Locally

Cloning the repository and depending on the modules locally is required when using some libraries. It's also a suitable approach if you want to make local changes, or if you want to use the main branch.

First, clone the repository into a local directory:

git clone https://github.com/androidx/media.git

Next, add the following to your project's settings.gradle.kts file, replacing path/to/media with the path to your local copy:

(gradle as ExtensionAware).extra["androidxMediaModulePrefix"] = "media3-"
apply(from = file("path/to/media/core_settings.gradle"))

Or in Gradle Groovy DSL settings.gradle:

gradle.ext.androidxMediaModulePrefix = 'media3-'
apply from: file("path/to/media/core_settings.gradle")

You should now see the AndroidX Media modules appear as part of your project. You can depend on them from build.gradle.kts as you would on any other local module, for example:

implementation(project(":media3-lib-exoplayer"))
implementation(project(":media3-lib-exoplayer-dash"))
implementation(project(":media3-lib-ui"))

Or in Gradle Groovy DSL build.gradle:

implementation project(':media3-lib-exoplayer')
implementation project(':media3-lib-exoplayer-dash')
implementation project(':media3-lib-ui')

MIDI module

By default the MIDI module is disabled as a local dependency, because it requires additional Maven repository config. If you want to use it as a local dependency, please configure the JitPack repository as described in the module README, and then enable building the module in your settings.gradle.kts file:

gradle.extra.apply {
  set("androidxMediaEnableMidiModule", true)
}

Or in Gradle Groovy DSL settings.gradle:

gradle.ext.androidxMediaEnableMidiModule = true

Developing AndroidX Media

Project branches

Development work happens on the main branch. Pull requests should normally be made to this branch.

The release branch holds the most recent stable release.

Using Android Studio

To develop AndroidX Media using Android Studio, simply open the project in the root directory of this repository.