http://www.linuxtv.org/vdrwiki/index.php/Osdpip-plugin

OSD Picture-in-Picture is a VDR PlugIn that displays the current channel
in a small box on the screen (default upper right corner). You can switch
up and down now, watching the progress of the previous channel in the box.
Quality is not too good yet, and only I-Frames are displayed.

WWW: http://projects.vdr-developer.org/projects/show/plg-osdpip