OVERVIEW

As far as USB is concerned, digital video is just like digital audio except that there is a lot more data! Digital video uses the same isochronous features of the USB architecture, so there is no new USB theory to learn. The high data rate of digital video, however, causes the operating system to be much more involved in the transfer of data; the Windows OS uses a kernel-mode streaming driver to process all video operations, and provides access and configurability via filter graphs (explained in detail later in this chapter). We shall see that inputting video into a PC host is a complex and specialized function, and dedicated components are built for this task. Each manufacturer solves this function in a different way, but all provide a Windows device driver to integrate their components into the Windows DirectShow architecture.

It is beyond the scope of this book to explain how these dedicated components are designed. My goal is to show how they can be used in a USB-based project. I will present three OEM solutions that are also purchasable as end-user products. For most readers, I recommend that you buy one of the end-user products and adapt it to suit your application. I will discuss several software examples in this chapter to get you started. If you intend to build thousands of your products, then I recommend that you work directly with the OEM supplier they have the expertise that you will need to make major modifications to designs...