What is GStreamer?
● Pipeline-based media framework
● Basic building blocks: elements connected via pads
● Set of libraries with abstract API
● Plugins for specific features
– Often wrapping other libraries, e.g. libav/ffmpeg, OpenCV,
various codec libraries
Alternative - gtkgst
● Renders your video into a GtkWidget provided by
the GStreamer sink
● Software implementation uses cairo into a
GtkDrawingArea
● Place the provided GtkWidget wherever in the
widget hierarchy
gtkgst - GL
● Gtk 3.16 has new GL support
● GStreamer 1.4 has GL support
● Why don't we try integrating them?
What is OpenGL?
● Low level 3D graphics API
● Been around since the 1990's
● Uses dedicated hardware
● Cross-platform
OpenGL in GStreamer
● Contained in the libgstgl library
● GstGLDisplay, GstGLContext are your two main
objects. Analogous to GdkDisplay and
GdkGLContext
● Element base classes, color conversion, uploaders,
GL version/extension checking
● Also contains various elements – gltestsrc,
glvideomixer, glimagesink, gleffects, etc
Implementation - gtkgst
● ~1000 lines of code
● Relies heavily on the GStreamer GL library and the
GL implementation
● Similar in style and scope to
avsamplebuffersink/caopengllayersink
gtkgst - GL
● Currently a proof of concept
● Currently X11 only
● System load causes frame jitter
● Uses Gtk+'s GL context
● Wayland might not be needed due to
efficient/correct subsurfaces
Uses
● Anytime you want to display video from GStreamer
into a Gtk+ application
– e.g. Videos/Totem