I'm on an HD 4000, Windows 8.1, latest drivers.
When using Miracast to view static photos I see "detail pumping". Looks like the video stream alternates between multiple smeared frames (lower quality delta frames, presumably), then a better detail frame (a keyframe). I don't see a reason for static images to degrade after they reach their full quality.
Are video encoding choices up to the sender? Can this be improved through drivers?