What is SDI? SDI stands for Serial Digital Interface, and is a way to transport digital component video between video devices. In this instance, the video device that generates the component video is a DVD player or satellite receiver and the video device that processes it is a home theater computer.

Why is SDI beneficial? First, you do not lose any video picture quality as the video is transported. Second, the video is retimed upon arriving at its destination, so the video should be smooth. Third, SDI signals can be sent long distances without loss of quality.

What do I have to do to take advantage of SDI? In this instance, you need either a DVD player or sat receiver and home theater computer that both have SDI connections. DVD players normally don't come with SDI connections, so you have to get one specially modified. SDI Silk is installed in your home theater computer to receive the video.

What else is required for the home theater computer to process the video? For best performance, for hardware you need a Radeon or GeForce 2 or higher video card and a CPU of about 1 GHz or greater. For software, you need the video processor application DScaler and many will want to use Powerstrip to dial in a good resolution and refresh rate for your display device.

Why bother with a home theater computer, when you can get a good scaler that has better ergonomics? That is a very valid question, whose answer hinges on price and personal preference. Scalers are normally several times more expensive than home theater computers and/or have limited upgrade capabilities.

Why bother buying an SDI DVD player and SDI input card, when I can use WinDVD? Again, a very valid question. The answer hinges on many factors, of varying importance to each videophile. First, SDI appears to have a better image than WinDVD and the other software players. Second, SDI should have smoother video, especially on pans. Third, on video source materials and on improperly mastered materials, the DScaler video processor discussed above is superior to the software players. There are other factors that you may consider. Normally, standalone DVD players have better controls than the software players. Also, standalone DVD players sometimes have other features, like DVD or SACD audio, for instance.

Does SDI offer advantages to sources other than DVD? Yes. Satellite receivers can be modified to output SDI. Currently, the SDI Silk card offers the only method for your home theater computer to receive uncompressed digital component satellite video.

I want to input good quality analog sources to my home theater computer. Can SDI help? Yes. There are SDI products on the market to convert to SDI from component, s-video, and composite. While not cheap, some of these solutions should produce fairly clean video for processing by DScaler.

What kind of cabling does SDI use? Standard 75 ohm cable with BNC connectors. Sometimes you will find 75 ohm cables with RCA connectors which will work OK too, if you buy two RCA > BNC converters.

My SDI input card only has one SDI input. Are there any switches available? Yes, switches for SDI are fairly inexpensive and are controlled in a variety of ways. Some have even reported success using cheap items such as antenna switches available at your local Radio Shack.

Why is SDI gear so expensive? In the past, SDI gear was used solely by professionals, where these prices did not affect how many people bought the gear. For videophiles, these rules no longer apply, and everybody is making progress in keeping the prices affordable for the vast majority.

Will there be any way to get the SDI advantage with the DVD player in your home theater computer? We don't know. The DScaler developers have looked at this a lot, but there appear to be challenges to making it happen at a satisfactory quality level for now.