Options Picture in Picture
Here you can setup the audio and video settings for Picture in Picture.
For an explanation of the DirectX settings please refer to Options DirectX.
Use VMR 9 Renderer
The DVBViewer uses in Windows XP the VMR 7-Renderer and for Vista/Windows 7 the EVR for the PiP. With this setting you can force the DVBViewer to use the VMR9 Renderer.
Some Video decoders do not work correctly with PiP. So you might have to experiment with them a little bit.