Thanks Christian. 

Is there any chance of the DirectShow grabber supporting adjustment of the 
video settings (brightness, contrast, etc.) like the QT grabber does?

Cheers.

-bill k



On Sep 25, 2012, at 9:01 AM, Christian Schmitz <[email protected]> 
wrote:

> 
> Am 24.09.2012 um 20:12 schrieb William Koperwhats <[email protected]>:
> 
>> Christian (et. al.),
>> 
>> I've got most of the pieces of the DirectShow version of my app figured out, 
>> but there is one thing that I am still confused about, that is dynamically 
>> updating the size of the DirectShow grabber frame. I see how this is 
>> accomplished in the example app, the DS video window is resized to match the 
>> size of the canvas. This effectively resizes the *window* image, but the 
>> actual frame (DirectShowSampleGrabber.Current) remains at the default size. 
> 
> Yes. Isn't the frame size the resolution of the camera?
> 
>> My app requires processing the grabber image *before* it gets displayed so I 
>> currently dynamically resize and move the DSVideoWindow "off screen" during 
>> the main window's "Resizing" and "Resized" events. In the graber NewFrame 
>> event I pass the Current [frame] to the main window for display. The problem 
>> is that the Current [frame] doesn't get resized with the video window. Using 
>> the QuickTime grabber class, all that was required was to re-initalize the 
>> QT frame buffer to the new window size, but this doesn't seem to be possible 
>> in DirectShow. I could process and scale the frame to match the new window 
>> size, but not only is that incredibly processor intensive, the frame has 
>> *already* been scaled for the (hidden) video window…
> 
> The image is not available in that size. The grabber gets it earlier in the 
> chain, so it has original size.
> 
>> 1. Is there some way to dynamically change the size of the 
>> DirectShowSampleGrabber.Current [frame]?
> 
> As far as I know: no
> 
>> 2. If not, what would be the most efficient method of accomplishing what I 
>> need to do?
> 
> Use draw picture with right destination size, so the gdi functions can scale 
> it. Hopefully with hardware acceleration.
> 
> 
> Greetings
> Christian
> 
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