Is it possible to change the system default video renderer?

[LigH]

If there is no DirectX installed, the "default" video renderer is possibly GDI functions.

If DirectX and a full featured graphic card and driver are installed, then it will usually be the "hardware overlay".

Is it at all possible to define any other renderer as "system default"?

And (hopefully a little easier question) is it possible to find out which kind of renderer is currently the "system default"? -- GraphEdit or GSpot (MS A/V: [1]) show no useful details, only "Video Renderer".

I guess it is possible to change the merits of several "renderer" DShow filters. But is this dangerous, may I mess the system if I try?
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Reason for the question:

Someone seems to have messed his system. Most probably by installing several kinds of "codec packs"... Using VMR9 instead of "System default" in MPC makes the video look fine again. And a parallel system doesn't have issues. Therefore I wonder: Would it be possible to define VMR9 as the default video renderer, for those players which don't support chosing a specific renderer?

German doom9/Gleitz board thread (http://forum.gleitz.info/showthread.php?t=35535)

[clsid]

The problem on that computer is likely a broken Overlay, which will cause problems for the Overlay Mixer and VMR-7 renderers. That is not caused by bad codecs but by bad graphics drivers.

You can force a renderer of choice by giving the other renderers a merit of 00000000.