You could send IOCTL_VIDEO_MAP_VIDEO_MEMORY to the miniport of the disp=
lay
driver. That should give you a user-accessable virtual address. Check t=
he
DDK for further details.
Beware however that video memory isn’t necessarily straight-forward
accessible (as in, the data isn’t necessarily ordered in the way you se=
e
them on the screen), so you may have to mangle the data from the video
memory to make it recognisable.
–
Mats
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xxxxx@lists.osr.com wrote on 11/26/2004 03:47:54 AM:
Thank you for your response!
I want to access video memory througth video0.
>Because video port driver creates \devcice\videoN with exclusive fla=
g
set.
>
>What do you want to accomplish by access video DO?
>
>-
>Calvin Guan Software Engineer
>ATI Technologies Inc. www.ati.com
>
>-----Original Message-----
>From: f [mailto:xxxxx@eyou.com]
>Sent: November 24, 2004 8:36 PM
>To: Windows System Software Devs Interest List
>Subject: [ntdev] Why I cannot open “Display1” ?
>
>Hi ,Everyone.
>I just take a test to open the video device “Display1” and to get a
>File_Object for accessing the video buffer . Code I used :
>
>PFILE_OBJECT VideoTest_OpenDisplayDevice(ULONG DisplayNumber)
>{
> WCHAR DeviceNameBuffer[40];
> UNICODE_STRING DeviceName;
> NTSTATUS Status;
> PFILE_OBJECT VideoFileObject;
> PDEVICE_OBJECT DeviceObject;
>
> swprintf(DeviceNameBuffer, L"\Device\Video%d", DisplayNumber);
> RtlInitUnicodeString(&DeviceName, DeviceNameBuffer);
>
> Status=3DIoGetDeviceObjectPointer(
> &DeviceName,
> FILE_READ_ATTRIBUTES,//FILE_ALL_ACCESS ,
> &VideoFileObject,
> & DeviceObject
> );
>
>
> if (!NT_SUCCESS(Status))
> {
> DbgPrint(“Status=3D0x%x\n”,(ULONG)Status);
> return(NULL);
> }
>
> return VideoFileObject;
>}
>
>The result is NULL, Status=3D0xc0000022,it means “STATUS_ACCESS_DENI=
ED”.
>Why?
>
>
>
>
>
>–http://www.eyou.com
>–=CE=C8=B6=A8=BF=C9=BF=BF=B5=C4=B5=E7=D7=D3=D0=C5=CF=E4 =D3=EF=D2=F4=
=D3=CA=BC=FE =D2=C6=B6=AF=CA=E9=C7=A9 =C8=D5=C0=FA=B7=FE=CE=F1 =CD=F8=
=C2=E7=B4=E6=B4=A2…=D2=DA=D3=CA=CE=B4=BE=A1
>
>–http://vip.eyou.com
>–=BF=EC=BF=EC=B5=C7=C2=BC=D2=DA=D3=CAVIP=D0=C5=CF=E4 =D7=A2=B2=E1=C4=
=FA=D6=D0=D2=E2=B5=C4=D3=C3=BB=A7=C3=FB
>
>
>
>—
>Questions? First check the Kernel Driver FAQ at
>http://www.osronline.com/article.cfm?id=3D256
>
>You are currently subscribed to ntdev as: xxxxx@ati.com
>To unsubscribe send a blank email to xxxxx@lists.osr.co=
m
>
>—
>Questions? First check the Kernel Driver FAQ at
http://www.osronline.com/article.cfm?id=3D256
>
>You are currently subscribed to ntdev as: unknown lmsubst tag argume=
nt:
‘’
>To unsubscribe send a blank email to xxxxx@lists.osr.co=
m–http://www.eyou.com
–=CE=C8=B6=A8=BF=C9=BF=BF=B5=C4=B5=E7=D7=D3=D0=C5=CF=E4 =D3=EF=D2=F4=
=D3=CA=BC=FE =D2=C6=B6=AF=CA=E9=C7=A9 =C8=D5=C0=FA=B7=FE=CE=F1 =CD=F8=
=C2=E7=B4=E6=B4=A2…=D2=DA=D3=CA=CE=B4=BE=A1–http://vip.eyou.com
–=BF=EC=BF=EC=B5=C7=C2=BC=D2=DA=D3=CAVIP=D0=C5=CF=E4 =D7=A2=B2=E1=C4=
=FA=D6=D0=D2=E2=B5=C4=D3=C3=BB=A7=C3=FB–http://sms.eyou.com
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…=BE=A1=D4=DA=D2=DA=D3=CA=B6=CC=D0=C5
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