helpme testcap

Hi,
i’m an absolute beginner in Windows driver develop. I need a video capture
driver that shows as output stream the screen. I’m starting to study
testcap sample i would ask u:
1- which is the function that manage the video source?
2- in which way can i change it to put as video source the screen?

thank u and sorry for my english
Franco Gambato

Let me see if I understand this correctly.

You have a video capture card, and you want to display the data captured on
the screen, yes?

The easiest way to achieve this would be to capture the data into a buffer
somewhere. The tell a user-mode application where this data is, and copy it
to a window owned by the user-mode application. You could use “overlay”
mechanisms supported by for instance DirectX to do this.

It would be pretty difficult to do the same thing in kernel mode, because
you’ll have to know lots of internal stuff that is only known to the
developers of the particular graphics chip in the machine. And there are at
least 5 different chip manufacturers, which all have an overall similar,
but in detail different approach to how things work. For instance, our
current model of chip supports at least three different formats for how the
actual pixels are stored in video memory, and only the display driver knows
which it’s using for a particular piece of video memory. And for a
different model of chip, it’s different again…

And of course, the first problem would be to find WHERE in the 128MB of
video memory your display resides. And it may well move during a
mode-change when the user changes from 1024 x 768 to 1280 x 1024, or some
such.

Or are you after actually copying the screen-data to somewhere? Again, I’d
suggest you think again if you think that this is suitable thing to do in a
driver. Just write a small user-mode application that grabs the screen
(there’s PLENTY of examples of how to do a screen-grab), and do something
with that (send it off over the net, or whatever you want to do).

If what you wanted to do is something different, please explain a bit
further regarding source and destination of data .


Mats

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xxxxx@lists.osr.com wrote on 12/03/2004 04:52:53 PM:

Hi,
i’m an absolute beginner in Windows driver develop. I need a video
capture
driver that shows as output stream the screen. I’m starting to study
testcap sample i would ask u:
1- which is the function that manage the video source?
2- in which way can i change it to put as video source the screen?

thank u and sorry for my english
Franco Gambato


Questions? First check the Kernel Driver FAQ at http://www.
osronline.com/article.cfm?id=256

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