GStreamer needs to perform a seek when changing playback rate. Snapping at next keyframe causes viewer to lose few seconds of video when changing playback speed (and ugly fast forward effect when dragging speed slider). Prevent all those issues by seeking to the nearest keyframe instead.
A signal telling that "something somewhere changed" that is emitted multiple times per second (when bitrate changes). Not useful at all and a disaster performance-wise.
Not useful anymore since the player does 1s interval by default and now supports changing seek mode without stopping playback (unlike config which worked only when stopped).
Notify signal is a little problematic here as we already post a signal from player while jumping between APP and API contexts. Limit and disable it where not needed.
