media3/extensions/opus/README.md

ExoPlayer Opus Extension

Description

The Opus Extension is a TrackRenderer implementation that helps you bundle libopus (the Opus decoding library) into your app and use it along with ExoPlayer to play Opus audio on Android devices.

Build Instructions (Android Studio and Eclipse)

Building the Opus Extension involves building libopus and JNI bindings using the Android NDK and linking it into your app. The following steps will tell you how to do that using Android Studio or Eclipse.

• Checkout ExoPlayer along with Extensions

git clone https://github.com/google/ExoPlayer.git

• Set the following environment variables:

cd "<path to exoplayer checkout>"
EXOPLAYER_ROOT="$(pwd)"
OPUS_EXT_PATH="${EXOPLAYER_ROOT}/extensions/opus/src/main"

• Download the Android NDK and set its location in an environment variable:

NDK_PATH="<path to Android NDK>"

• Fetch libopus

cd "${OPUS_EXT_PATH}/jni" && \
git clone git://git.opus-codec.org/opus.git libopus

• Run the script to convert arm assembly to NDK compatible format

cd ${OPUS_EXT_PATH}/jni && ./convert_android_asm.sh

Android Studio

For Android Studio, we build the native libraries from the command line and then Gradle will pick it up when building your app using Android Studio.

• Build the JNI native libraries

cd "${OPUS_EXT_PATH}"/jni && \
${NDK_PATH}/ndk-build APP_ABI=all -j4

• In your project, you can add a dependency to the Opus Extension by using a rule like this:

// in settings.gradle
include ':..:ExoPlayer:library'
include ':..:ExoPlayer:opus-extension'

// in build.gradle
dependencies {
    compile project(':..:ExoPlayer:library')
    compile project(':..:ExoPlayer:opus-extension')
}

• Now, when you build your app, the Opus extension will be built and the native libraries will be packaged along with the APK.

Eclipse

• The following steps assume that you have installed Eclipse and configured it with the Android SDK and Android NDK :
  • Navigate to File->Import->General->Existing Projects into Workspace
  • Select the root directory of the repository
  • Import the following projects:
    • ExoPlayerLib
    • ExoPlayerExt-Opus
    • If you are able to build ExoPlayerExt-Opus project, then you're all set.
    • (Optional) To speed up the NDK build:
      • Right click on ExoPlayerExt-Opus in the Project Explorer pane and choose Properties
      • Click on C/C++ Build
      • Uncheck Use default build command
      • In Build Command enter: ndk-build -j4 (adjust 4 to a reasonable number depending on the number of cores in your computer)
      • Click Apply

You can now create your own Android App project and add ExoPlayerLib along with ExoPlayerExt-Opus as a dependencies to use ExoPlayer along with the Opus Extension.

Building for various Architectures

Android Studio

The manual invocation of ndk-build will build the library for all architectures and the correct one will be picked up from the APK based on the device its running on.

Eclipse

libopus can be built for the following architectures:

• armeabi (the default - does not include neon optimizations)
• armeabi-v7a (choose this to enable neon optimizations)
• mips
• x86
• all (will result in a larger binary but will cover all architectures)

You can build for a specific architecture in two ways:

• Method 1 (edit Application.mk)
  • Edit ${OPUS_EXT_PATH}/jni/Application.mk and add the following line APP_ABI := <arch> (where <arch> is one of the above 4 architectures)
• Method 2 (pass NDK build flag)
  • Right click on ExoPlayerExt-Opus in the Project Explorer pane and choose Properties
  • Click on C/C++ Build
  • Uncheck Use default build command
  • In Build Command enter: ndk-build APP_ABI=<arch> (where <arch> is one of the above 4 architectures)
  • Click Apply

Other Things to Note

• Every time there is a change to the libopus checkout:
  • Arm assembly should be converted by running convert_android_asm.sh
  • Clean and re-build the project.
• If you want to use your own version of libopus, place it in ${OPUS_EXT_PATH}/jni/libopus.