DirectShow Filter Graph Spy: 64-bit version and hook API

Today’s update for DirectShow Filter Graph Spy introduces 64-bit version (mind the beta state) and a mini-API for an external module to be involved into graph building process.

Filter Graph Spy is offering three new interfaces that provide extensibility of the spy:

• IFilterGraphAddRemoveHook
• IFilterGraphConnectHook
• IFilterGraphStateControlHook

The interfaces are contained in the type library and can be imported using #import directive. An implementation of one or more of these interfaces will receive hook style calls corresponding to respective Filter Graph Manager calls, system wide including in context of other applications.

A COM object may be registered as a hook object with Spy and NoThreadSpy COM classes under predefined registry keys:

Spy will instantiate the registered hook objects and forward them the calls it receive, before passing them to system Filter Graph Manager object. A hook object has an option to override default processing, including, for example, inserting its own filter in between. For example, IFilterGraph::Reconnect call is implemented the following way:

STDMETHOD(Reconnect)(IPin* pPin) throw()
{
    _Z4(atlTraceCOM, 4, _T("...\n"));
    HOOK_PROLOG(CFilterGraphConnectHookHost)
        OnReconnect(pT, pPin, &bDefault);
    HOOK_EPILOG()
    return m_pInnerFilterGraph2->Reconnect(pPin);
}
Before passing the call to original Reconnect method, spy is iterating through associated hooks, passing them IFilterGraphConnectHook::OnReconnect call. Setting bDefault parameter to FALSE will prevent spy from passing the call to original method.
Included BdaHooks project shows a sample implementation of the hooking COM classes (note .rgs registration).
Filter Graph Spy is compatible with all current Windows operating systems, 32-bit and 64-bit (x64), in particular including:

Windows 7
Windows Server 2008
Windows Vista
Windows Server 2003
Windows XP
Windows 2000

NOTE: DirectShow Filter Graph Spy is NOT suitable for production environment, it is NOT licensed to be redistributed to be a part of production state software item.
Partial Visual C++ .NET 2008 source code is available from SVN, release binary included (Win32, x64); installation instructions are in another post.