Re: Multi-monitor test-and-feedback app for Windows

Jean-Pierre Gygax wrote:

Whether XP can always do it (or Vista using the XP driver model), I'm slightly less sure. But you can sort of observe what happens e.g with VLC (the VideoLAN media player) - the window moves, but the image gets cut off.

The reason for that is that the video buffer is an "overlay", some sort of direct-memory-giveto. The hardware takes a adress of video memory and displays it at a fixed position in screen space, almost as if you would "overlay" an analogue PIP video signal on a analogue carrier, you directly mess with the "state" for the display-device instead of the source.
That's why you also get popping delays while moving an "overlay", the GUI-state and the "overlay"-state are on two different sides of the render process, and very difficult to synchronize.
And well that's the reason why you get the image cut off, the address can for obvious reasons not be on a mem-chip of the other card. Of course it's being a bit lazy also, making aligned "overlays" on two cards with time-sync is possible; maybe not nice though.

AFAIK, I'm no real expert. :)

Ciao
Niels
.

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