Servo Media

The servo-media crate contains the backend implementation to support all Servo multimedia related functionality. This is:

• the HTMLMediaElement and the <audio> and <video> elements.
• the WebAudio API.
• the WebRTC API.
• the Media Capture and Streams APIs.

servo-media is supposed to run properly on Linux, macOS, Windows and Android. Check the build instructions for each specific platform.

servo-media is built modularly from different crates and it provides an abstraction that allows the implementation of multiple media backends. For now, the only functional backend is GStreamer. New backend implementations are required to implement the Backend trait. This trait is the public API that servo-media exposes to clients through the ServoMedia entry point. Check the examples folder to get a sense of how to use it effectively. Alternatively, you can also check how servo-media is integrated and used in Servo.

Requirements

So far the only supported and default backend is GStreamer. So in order to build this crate you need to install all gstreamer-rs dependencies for your specific platform as listed here.

Ubuntu Trusty

Ubuntu Trusty has very old GStreamer packages (1.2, while we need at least 1.16), so you need to manually build GStreamer >1.16 or alternatively run the etc/ubuntu_trusty_bootstrap.sh shell script, which downloads a pre-built bundle and sets up the required environment variables:

source etc/ubuntu_trusty_bootstrap.sh

Android

For Android there are some extra requirements.

First of all, you need to install the appropriate toolchain for your target. The recommended approach is to install it through rustup. Taking arm-linux-androideabi as our example target you need to do:

rustup target add arm-linux-androideabi

In addition to that, you also need to install the Android NDK. The recommended NDK version is r16b. The Android SDK is not mandatory but recommended for practical development.

Once you have the Android NDK installed in your machine, you need to create what the NDK itself calls a standalone toolchain.

 $ ${ANDROID_NDK}/build/tools/make-standalone-toolchain.sh \
   --platform=android-18 --toolchain=arm-linux-androideabi-4.9 \
   --install-dir=android-18-arm-toolchain --arch=arm

After that you need to tell Cargo where to find the Android linker and ar, which is in the standalone NDK toolchain we just created. To do that we configure the arm-linux-androideabi target in .cargo/config (or in ~/.cargo/config if you want to apply the setting globaly) with the linker value.

[target.arm-linux-androideabi]
linker = "<path-to-your-toolchain>/android-18-toolchain/bin/arm-linux-androideabi-gcc"
ar = "<path-to-your-toolchain>/android-18-toolchain/bin/arm-linux-androideabi-ar"

This crate indirectly depends on libgstreamer_android_gen: a tool to generate the required libgstreamer_android.so library with all GStreamer dependencies for Android and some Java code required to initialize GStreamer on Android.

The final step requires fetching or generating this dependency and setting the pkg-config to use libgstreamer_android.so. To do that, there's a helper script that will fetch the latest version of this dependency generated for Servo. To run the script do:

cd etc
./android_bootstrap.sh <target>

where target can be armeabi-v7 or x86.

After running the script, you will need to add the path to the pkg-config info for all GStreamer dependencies to your PKG_CONFIG_PATH environment variable The script will output the path and a command suggestion. For example:

export PKG_CONFIG_PATH=/Users/ferjm/dev/mozilla/media/etc/../gstreamer/armeabi-v7a/gst-build-armeabi-v7a/pkgconfig

If you want to generate your own libgstreamer_android.so bundle, check the documentation from that repo and tweak the helper script accordingly.

Build

For macOS, Windows, and Linux, simply run:

cargo build

For Android, run:

PKG_CONFIG_ALLOW_CROSS=1 cargo build --target=arm-linux-androideabi

Running the examples

Android

Make sure that you have adb installed and you have adb access to your Android device. Go to the examples/android folder and run:

source build.sh
./run.sh