Controlling the WDM Image Capture Control

Question

_{Tuesday, February 7, 2017 12:20 PM}

Number of issues, most of which, I suspect, can be solved by appropriate registry entries.

So where can we find a listing of the relevant registry entries to programatically control the following attributes of the WDM form

1 its on screen size. Typically need it to be double the default, so that the user can actually see and work with whatever it is they are trying to snapshot

2 its choice of source. Every time we invoke the control, the user has to select the relevant device (even if there is only one). How do we make the control "remember" its last choice, or stuff a registry setting with the appropriate value

3 ditto its choice of image format.

4 while we're talking image format, I've got a camera plugged in to a laptop. When the WDM appears, it correctly recognises the max res for the camera as 1280x768 but that option doesn't appear in the list of available formats. Why not? Can we force the control to accept that resolution, given the camera has that capability?

5 In several scenarios, I get a single shot at taking a photograph. If I try a retake or a second shot, the system fails with

"video datasource is off-line or not responding", when it clearly isn't.  I suspect this is a failure to release a handle or similar but it's not obvious what I can do to clear it.

6 Most importantly, having done all these tweaks, either programatically or manually, how can we force the control to memorise them, preferably as long term defaults but, if not, at least for the windows session we're in?

All replies (1)

_{Wednesday, February 8, 2017 1:59 AM}

Hi,

Please check this official documentation for more information.

Windows Driver Model (WDM)

https://msdn.microsoft.com/en-us/library/windows/hardware/ff565698(v=vs.85).aspx

All new drivers were WDM drivers for 15+ years. In order to provide backward compatibility later between VFW and WDM, Microsoft came out with Microsoft WDM Image Capture (Win32) driver. Windows versions up to Windows 10 include it, and it is the only VFW driver in the system. In turn, it manages one of existing WDM-driver devices of choice and exposes video capture functionality to VFW applications. If there are two or more WDM drivers, the VFW driver offers to choose between the devices.

In fact, for WDM question, I suggest to ask for help from Windows hardware WDK and Driver development forum, the reason why we recommend posting appropriately is you will get the most qualified pool of respondents, and other partners who read the forums regularly can either share their knowledge or learn. Thanks for your understanding and cooperation.

https://social.msdn.microsoft.com/Forums/windowsdesktop/en-US/home?forum=wdk

Regards

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