title: Including a .idl file in a C++ project
body: <p>I'm building a project in C++ which uses DirectShow's video capture library to connect to a camera. The video card manufacturer (BlackMagic) has provided .idl (Interface Definition Language) files which add new capture graphs to the standard collection.</p>
  
  <p>Thing is, I've never come across a .idl file, and the very vague "include the file" direction doesn't help much. Including it with a #include directive doesn't throw up any errors, but the program also fails to pull in the various definitions which I presume it's intended to add, since it's the only file I'm told to include with the project.</p>
  
  <p>My question is: how should one include a .idl file in a project?</p>