While the other pinned thread (http://forums.microsoft.com/MSDN/ShowPost.aspx?PostID=2234589&SiteID=1) contains a variety of Microsoft-related DirectShow resources, here are some non-Microsoft links:
Two excellent sites for general-purpose DirectShow information. They contain sample code, whitepapers, and FAQs:
http://tmhare.mvps.org/
http://www.gdcl.co.uk/
For developers interested in using Managed Code to access DirectShow, this site contains samples, libraries, and a discussion forum:
http://DirectShowNet.SourceForge.net
DirectShow Training:
http://www.roujansky.com/index.php
And while this is a Microsoft link, it isn't mentioned in the other pinned thread, so I thought I'd include it here:
http://blogs.msdn.com/mikewasson/
And, as always, search engines are your friends. A simple Google for "DirectShow" turns up > 400,000 hits. What you need may already be out there, so do a search!