TV or not TV? That is the question. (NTSC video cards)
by David English
If your graphics card and monitor are your computer's video system why can't you just hook up your television to your computer? Or why can't you run a cable to your VCR, pop in a videocassette, and paste Aunt Ethel into your paint program? Better yet, why can't you use your paint program to create a colorful title (something like Our Summer in the Rockies) and zap it down your monitor's cable directly into your family's vacation tape?
After all, it isn't so hard to bring text--or even sound--into and out of your PC. So what's so special about video? And how much money do you have to spend before you can send Aunt Ethel dancing across your computer screen?
More than anything else, it's a question of standards. All television equipment in the U.S. must conform to the NTSC (National Television Standards Committee) specifications.
Because your TV, VCR, video camera, and laser disc player speak the same video language, you can hook them together without giving it a second thought. Each of these video devices displays the same number of horizontal scan lines, uses a particular kind of interlaced blanking, and alters the phase of the chroma signal to create a specific range of colors.
Even though any NTSC device can accept the video signal from any other NTSC device, you run into trouble if you try to mix two or more signals together. Video devices have to be synchronized with each other, as well as with the NTSC standard. Because videotape can stretch, you'll also need a time-base corrector (TBC) to compensate for timing deviations from the NTSC standard.
That's just on the video side. When you try to bring NTSC video to your computer, you'll have to deal with overscanning, different horizontal and vertical sync rates, and different aspect ratios. It's no small feat to design a card that can send a video image to your computer screen and have it look at all like its earlier form.
Fortunately, the situation is improving. Faster processors and higher-resolution monitors are driving a whole new generation of affordable NTSC video cards. While we're a long way from plug-and-play video, with a bit of patience and a lot of perseverance, you can begin to bridge the gap between TV and CPU. NewTek, for instance, has a Video Toaster/Amiga product that interfaces with the PC.
If all you want to do is watch TV on your computer, check out DESKTOPTV (AVVIEW Technology, 2401 North Forest Road, Buffalo, New York 14226; 800-866-7288; $395). It's a full-size card that lets you display live video on your computer screen. The card includes a built-in 119-channel television tuner, which you can control from either of two DESKTOPTV programs--a TSR or a Windows application.
Before you get too excited about the possibilities of watching "I Love Lucy" reruns in the corner of your Excel spreadsheet, let me bring you back down to earth. Only the high-end (and very expensive) video cards let you see computer and full-motion video images simultaneously. With DESKTOPTV, you can view one or the other--but not both at the same time. You can listen to the sound all the time, so if you hear something interesting, you can quickly pop over and see what's going on. But with this system, it's an either/or situation--your screen is either a computer monitor or a television set.
If you want to bring a video image into one of your programs, take a look at ComputerEyes/Pro (Digital Vision, 270 Bridge STreet, Dedham, Massachusetts 02026; 617-329-5400; $399.95) and VideoLinX: Frame-Buffer (VideoLinX, 20111 Stevens Creek Boulevard, Suite 100, Cupertino, California 95014; 800-222---42; $695.00). Both let you grab a single video image and convert it to a standard PC graphics file. ComputerEyes/Pro can accept composite video or the higher quality S-video (used by Super-VHS and Hi 8 video recorders). It can convert to PCX, TIFF, Targa, ColoRIX, and other formats.
VideoLinX: FrameBuffer includes video out as well as video in. The video in works much like the ComputerEyes card by converting individual composite-video images to PCX, Targa, TIFF, and other formats. The video out operates in the other direction, converting graphics files into video pictures that you can display on a television set or record on a VCR. Keep in mind that these are individual pictures, not moving images. To create animation with the FrameBuffer, you would need to purchase a special $2,000 VCR with single-frame capability.
Both cards support (but can't display) 24-bit color for 16.7 million colors. (Most programs that handle 24-bit color files will display them in 16 or 256 colors with VGA or Super VGA cards.) FrameBuffer lets you view 24-bit color files on your TV--a real plus if you work with 24-bit color but don't have a 24-bit color graphics card.
So how much money does it take to have Aunt Ethel dance across your computer screen? At this point, live full-motion video is still just around the corner. But with lower hardware prices and Multimedia Windows, Auntie may be ready to do her thing sometime in late 1991.