In media performance test, one important indicator is real time frame rate. Usually, it’s difficult to get the data at media framework(such as GStreamer and helix) since it depends on different demux, also it’s undefined to get the framerate at media player(such as totem) level since many media player has no such option.
The tool is based on XDamage extension. The frame rate is got by counting the number of XDamage notification event received per second. With XDamage, X server will sent notification to client once there is Drawable modification.