WebRTC Android development

Getting the Code

Android development is only supported on Linux.

  1. Install prerequisite software

  2. Create a working directory, enter it, and run:

$ fetch --nohooks webrtc_android
$ gclient sync

This will fetch a regular WebRTC checkout with the Android-specific parts added. Notice that the Android specific parts like the Android SDK and NDK are quite large (~8 GB), so the total checkout size will be about 16 GB. The same checkout can be used for both Linux and Android development since you can generate your Ninja project files in different directories for each build config.

See Development for instructions on how to update the code, building etc.

Compiling

  1. Generate projects using GN.

Make sure your current working directory is src/ of your workspace. Then run:

$ gn gen out/Debug --args='target_os="android" target_cpu="arm"'

You can specify a directory of your own choice instead of out/Debug, to enable managing multiple configurations in parallel.

  • To build for ARM64: use target_cpu="arm64"
  • To build for 32-bit x86: use target_cpu="x86"
  • To build for 64-bit x64: use target_cpu="x64"
  1. Compile using:
$ autoninja -C out/Debug

(To list all available targets, run autoninja -C out/Debug -t targets all.)

Using the Bundled Android SDK/NDK

In order to use the Android SDK and NDK that is bundled in third_party/android_tools, run this to get it included in your PATH (from src/):

$ . build/android/envsetup.sh

Then you'll have adb and all the other Android tools in your PATH.

Running the AppRTCMobile App

AppRTCMobile is an Android application using WebRTC Native APIs via JNI (JNI wrapper is documented here).

For instructions on how to build and run, see examples/androidapp/README.

Using Android Studio

Note: This is known to be broken at the moment. See bug: https://bugs.webrtc.org/9282

  1. Build the project normally (out/Debug should be the directory you used when generating the build files using GN):
$ autoninja -C out/Debug AppRTCMobile
  1. Generate the project files:
$ build/android/gradle/generate_gradle.py --output-directory $PWD/out/Debug \
  --target "//examples:AppRTCMobile" --use-gradle-process-resources \
  --split-projects --canary

  1. Import the project in Android Studio. (Do not just open it.) The project is located in out/Debug/gradle. If asked which SDK to use, choose to use Android Studio's SDK. When asked whether to use the Gradle wrapper, press “OK”.

  2. Ensure target webrtc > examples > AppRTCMobile is selected and press Run. AppRTCMobile should now start on the device.

If you do any changes to the C++ code, you have to compile the project using autoninja after the changes (see step 1).

Note: Only “arm” is supported as the target_cpu when using Android Studio. This still allows you to run the application on 64-bit ARM devices. x86-based devices are not supported right now.

Running Tests on an Android Device

To build APKs with the WebRTC native tests, follow these instructions.

  1. Ensure you have an Android device set in Developer mode connected via USB.

  2. Compile unit tests and/or instrumentation tests:

$ autoninja -C out/Debug android_instrumentation_test_apk
$ autoninja -C out/Debug rtc_unittests
  1. You can find the generated test binaries in out/Debug/bin. To run instrumentation tests:
$ out/Debug/bin/run_android_instrumentation_test_apk -v

To run unit tests:

$ out/Debug/bin/run_rtc_unittests -v

Show verbose output with -v and filter tests with --gtest-filter=SomeTest.*. For example:

$ out/Debug/bin/run_android_instrumentation_test_apk -v \
    --gtest_filter=VideoFrameBufferTest.*

For a full list of command line arguments, use --help.

  1. NOTICE: The first time you run a test, you must accept a dialog on the device!

If want to run Release builds instead; pass is_debug=false to GN (and preferably generate the projects files into a directory like out/Release). Then use the scripts generated in out/Release/bin instead.