libgstreamer_android_gen

This tool generates a libgstreamer_android.so library with all GStreamer dependencies for Servo Media and some Java code required to initialize Gstreamer on Android.

It makes use of GStreamer ndk-build Makefiles that in summary do:

• override the path of the pkg-config files
• collect all gstreamer plugins that were selected and their dependencies
• generate a C source file that does the gstreamer/android initialization
• link all this together into a single libgstreamer_android.so, which is necessary for non-latest Android as the number of shared libraries a process can load was seriously limited (64 or so? you can easily have that many gstreamer plugins)
• provide a GStreamer.java that loads all this

Build

Install the Android NDK. The recommended NDK version is r16b.

Download GStreamer prebuilt binaries for Android. The current version known to work with gstreamer-rs is 1.14.3

The ndk-build Makefiles need to know where you installed the GStreamer binaries. You must define an environment variable called GSTREAMER_ROOT_ANDROID and point it to the folder where you extracted the GStreamer binaries. This environment variable must be available at build time, so maybe you want to make it available system-wide by adding it to your ~/.profile file.

If you need to add extra GStreamer plugins, list them here.

Finally run:

./build.sh

This should generate an out folder containing a zip file per architecture including the libgstreamer_android.so and a src.zip file with the generated GStreamer.java among others.

Deploy

The GStreamer binaries per each platform are deployed to Servo's AWS S3 space.

In order to deploy new binaries you need the s3cmd tool and authorized access to Servo's S3.

The generated binaries are named with this nomenclature: gstreamer-<target>-<version>-<date>-<time>.zip and are meant to be uploaded to http://servo-deps.s3.amazonaws.com/gstreamer.

An example command to upload new binaries to http://servo-deps.s3.amazonaws.com/gstreamer/gstreamer-armeabi-v7a-1.14.3-20181004-142930.zip:

./s3cmd put ~/dev/gstreamer/libgstreamer_android_gen/out/gstreamer-armeabi-v7a-1.14.3-20181004-142930.zip s3://servo-deps/gstreamer/gstreamer-armeabi-v7a-1.14.3-20181004-142930.zip -P

Known issues

• Android binaries have text relocations. Prevents usage on Android >= 5.0. The current workaround involves removing the openh264 plugin from the list of plugins for the x86 arch. The plugin list is located at $GSTREAMER_ROOT_ANDROID/*/share/gst-android/ndk-build/plugins.mk

• nice is missing from the plugins list in versions <= 1.14.4. We need to manually add it to $GSTREAMER_ROOT_ANDROID/*/share/gst-android/ndk-build/plugins.mk