I am new at DirectShow, so some parts of this library i don\'t understand well. I already see the example DxSnap, but i need to capture frames without previewing it
If your main concern is "access webcam" and not "access webcam with DirectShow", then I would have a look at the AForge.NET-Framework. I tried it with DirectShow once just to find out that I could do the same thing with multiple video sources in less time with less code.
Here is some sample code: Access to USB cameras and video files using DirectShow