Finely tuned, or finally tuned?
HDTV on the PC: Lucid images and lousy reception.
Maury Wright, Executive Editor

With widely available HDTV add-in cards for the PC just around the corner, I set out to evaluate PC-based HDTV. Little did I know that I would learn far more valuable lessons, such as how difficult it can be to tune in an HDTV broadcast, and—in a blast from the past—the ins and outs of TV antennas.

Before we jump into my tale of woe, it's only fair to justify PC-based HDTV as a legitimate product whose market extends far beyond a few hobbyists. Using a PC to watch NTSC (regular) TV has proven popular in several market segments. Teens and college students, the so-called "Generation Y," often use a PC as their primary TV. Moreover, financial analysts, stockbrokers, news reporters, and others depend on the technology in their jobs. Cahners In-Stat Group predicts that the worldwide market for PC-based DTV tuners will hit 3 million units by 2003 and 20 million units by 2004.

At the start, I felt relatively confident that I would be able to test three scenarios for PC-based HDTV reception.

Option 1—the only one I succeeded in testing—features an add-in card with a demodulator, a tuner, and a hardware-based MPEG-2 decoder that can handle the rich HDTV stream. No one is actually shipping such a card today. Hauppauge comes close with an SDTV (standard-definition digital television) card, which, FYI, delivers much better picture quality than a regular NTSC signal. But HDTV cards are coming, and TeraLogic provided me with a reference design based on its Janus chip. Consumer products based on this design should start appearing around mid-year from Creative, Hauppauge, Panasonic, and perhaps others.

In Option 2, a card provides HDTV tuning and demodulation, but the host PC's processor decodes the MPEG-2 stream. This is called software MPEG-2 decoding, and it's widely deployed today for decoding DVD signals. HDTV has far higher resolution, so it stresses the host processor to a greater degree. Ravisent Technologies leads the market for software MPEG-2 decoders, and will likely be first provide an HDTV decoder.

In Option 3, a PC graphics accelerator includes functions that specially target the decoding function. ATI Technologies has led the way in this space. ATI's graphics chips include hardware that helps crunch through two critical MPEG-2 decoding tasks: motion compensation and a mathematical operation called an IDCT (inverse discrete cosine transform). This means decoding consumes far less of the host processor's horsepower. So a user with a less-powerful PC can still decode video, and a user with a high-end system can decode video and still have plenty of juice left for game playing, web surfing, or perhaps, on occasion, working.

Of course, Option 3 still requires a tuner and a demodulator. In the past, ATI has packaged an NTSC tuner and graphics processor together in its All-In-Wonder graphics card family. But for the DVD-decoding task, the company ships a specialized version of Ravisent's DVD software, which leverages the graphics card's motion-compensation and IDCT capabilities. When an HDTV version ships, it's unclear whether it will be on a single card. ATI and its partners, Ravisent and Conexant, have been showing a two-card reference design that includes a tuner/demodulator card and an ATI graphics card.

As you might guess, price explains why we have three choices on the horizon.

Clearly, the all-hardware approach (Option 1) is the most robust. You won't need a bleeding-edge PC to run it. TeraLogic says even a 350-MHz Celeron would work for its Janus product. But you pay for such a powerful card. TeraLogic expects Janus-based cards to cost at least $300. Incidentally, it appears the card could even work in less-powerful PCs, but the company sets the bar according to the least-muscular systems currently for sale. TeraLogic's scheme does require some host processing power, to decode the Dolby Digital audio that's included in the HDTV stream.

Prices for the software-only and hardware-assist products (Options 2 and 3) will be much lower. ATI, for instance, has at times given away DVD-decoding software. At most, users paid $10 or $20 for the code. Compared to regular graphics cards, the All-In-Wonder card with the TV tuner sometimes commanded a $10 to $50 premium, but has generally been priced competitively. Overall, you can expect to spend around $100 to add software-only or hardware-assisted HDTV to your PC.

Intense

As things stand today, it appears that you'd need a 733-MHz Pentium III system to handle software-only HDTV, and the task would still consume 85 to 90 percent of the host processor's time. In contrast, ATI claims that a 600-MHz Pentium III system equipped with an ATI graphics chip could do the job, with 25 to 30 percent of its attention left for other applications.

But even a user with a spanking new GHz box might want to consider the hardware or hardware-assisted approach. TeraLogic argues that its all-hardware design will more capably handle the varied ways broadcasters can use the HDTV spectrum. For example, rather than broadcasting a single football game in HDTV, a broadcaster might deliver four games in SDTV resolution. You could choose the hottest rivalry, or watch them all on a four-way split screen. Hey, I'd do it. TeraLogic promises its design will handle the simultaneous decoding of all four streams, while other approaches will fail.

Likewise, ATI recommends hardware-assist, even for users who have power to burn. For example, you could use a video-enabled PC as a digital VCR, similar to products from TiVo and ReplayTV, which even let you "pause" live programs. This app requires simultaneous encoding of the incoming NTSC signal and decoding of a stored NTSC-quality MPEG-2 stream. ATI claims its graphics processor handles the bulk of the decoding task and leaves the PC free to handle the encoding in software, whereas even a GHz PC wouldn't be able to perform both functions in software.

Where's the meat?

So all hype aside, when will we see the products? All three types were supposed to be here already, but similar problems have delayed all three.

Making an HDTV product simple enough for the consumer turns out to be quite complicated. First, manufacturers must make it easy to install the board and the appropriate drivers in PCs that are increasingly laden with network cards, high-end sound boards, and even broadband modems. Second, as I found, HDTV broadcasting is still in its infancy. Even a properly installed board may not receive an HDTV signal. Manufacturers are extremely concerned, and rightfully so, that their products will get blamed for problems that should be laid at the feet of HDTV's neonatal status.

Trust me though, the boards are coming soon. At April's NAB (National Association of Broadcasters) show, Hauppauge demonstrated its Janus-based WinTV-HD card and promised June shipments. However, the company expects initial pricing in the $500 range, a far cry from the $300 TeraLogic has estimated.

When I dug into this project, it appeared that an SDTV card from Hauppauge or a preproduction TeraLogic card would be my only options. When I contacted TeraLogic about the Janus card, the company proved enthusiastic, but also conservative. I wanted to install the card myself, but I've been known to be overconfident about such things. TeraLogic insisted I'd be better off skipping that step, given that I'd be using a reference design rather than a polished product. I was in no position to argue, so TeraLogic shipped me a 350-MHz PC with the card already installed. Despite this spoon feeding, I still had plenty of adventure ahead.

When the PC hit my front door, I realized that I didn't even know what type of antenna I might need to capture an HDTV broadcast, nor did I know for certain that the network affiliates in my area (San Diego) were broadcasting digital signals.

Time to do some research. I'd previously discovered www.digitaltelevision.com, a site I'd recommend to anyone with DTV questions. The site will either have the info you need, or a link to it.

Right off the bat, that site led me to TitanTV.com and antennaweb.org. TitanTV confirmed several HDTV broadcasts in my area, and recommended local businesses that would sell and install an antenna. Of course, I wouldn't have turned to such help in any case, and my needs were temporary, so I moved on to antennaweb.com. Sponsored by the CEA (Consumer Electronics Association), this site draws a map of your locale, shows the directions from which the NTSC and ATSC (Advanced Television Systems Committee, another name for HDTV) broadcasts emanate, and lists all of the broadcasters.

The site ranks the signals according to how easy or difficult they should be to receive. Click on the station you're intent on watching, and the site makes a specific antenna recommendation. I clicked on the most difficult broadcast, and the site recommended a medium-strength, amplified, directional antenna. For the easiest broadcast, the site suggested a plain directional antenna.

The site conveys its recommendations with a simple color-coded symbol—a circle containing color wedges (see Figure). The more wedges you see, the more complex your antenna needs to be. Once you know the proper symbol for your location and your chosen broadcast(s), you bebop on down to the antenna store and find a product with a matching symbol.

I wasn't sure I wanted to install a rooftop antenna, perhaps because I remember such a product being a great frustration to my dad. My experience with antennas has been limited to DirecTV dishes, which are pretty simple to install. HDTV broadcasters generally deliver HDTV via a UHF channel, usually from the same tower as their regular signals. Experts cite a rule of thumb: If you can receive the station's NTSC signal without ghosting, you should be able to grab the HDTV signal.

Using rabbit ears in my home, I get a pretty bleak picture from the major network affiliates, so I knew I needed a better antenna. It just so happens that I have a fairly hip antenna installed atop my ancient motor home. This antenna has both a DirecTV dish and a small omnidirectional amplified antenna for UHF and VHF. I quickly joined several long pieces of coax and snaked them from the RV into my home office.

So much for rules of thumb

I hooked the cable to a portable TV and saw flawless NTSC pictures from the local ABC and CBS stations (the easiest, according to antennaweb.com). Encouraged, I connected the cable to the Janus board and started the TeraLogic TV application. The simple user interface allows you to choose NTSC or ATSC signals. Of course I immediately chose ATSC and started toying with the up and down channel arrows. Not only did I not get an HDTV signal, I couldn't even coax the tuner to the proper channels for the local affiliates.

Like many modern TVs, the tuner program requires that you set up the channels in your area.

MOBILE TEST: Seeking an elusive HDTV signal, the intrepid author, shown here with his son, drove his antenna-equipped recreational vehicle straight to the source.

I swapped back to NTSC mode, went through the channel setup procedure, and got good reception on numerous UHF and VHF NTSC signals. This was my first exposure to what's potentially a huge problem for first-time HDTV adopters. Unlike regular TV, when something's amiss with HDTV, you don't even get a lousy picture. You get a blank screen.

Next I went back to where I probably should have started. I used the TeraLogic software to play an HDTV sequence that had been prerecorded on the hard disk. I watched a short football sequence in lurid detail, and then a nature sequence, which my 9-year-old son later replayed a dozen times. HDTV is compelling.

The next day, I tried again. This time I asked the tuner application to automatically scan and find all local signals. It found only CBS, even though the CBS and ABC signals come from the same mountain and with supposedly the same broadcast power. Even though the tuner could detect the signal, I still got no picture.

The plot thickens

Up to that point, I hadn't connected speakers to the PC. When I did so, I was surprised to hear audio from the invisible CBS HDTV broadcast. I deduced a hardware problem and called TeraLogic.

TeraLogic assured me that the decoder was functioning, since I was able to play the prerecorded sequence. The company convinced me that my antenna was the problem. Since the audio and video get decoded separately, it's possible to receive audio even while dropped packets keep the video buffer from filling. I contemplated a better antenna to verify this diagnosis.

Now, I've spent money stupidly many times, but even I wouldn't normally consider installing a rooftop antenna for a simple test. However, this was the weekend of the NCAA basketball finals. CBS, with support from Thomson Consumer Electronics (RCA), was going to broadcast the Final Four games in HDTV. I'd planned to spend the weekend in front of my 19-inch computer monitor watching the action. So, off to Radio Shack—probably the first stop for most North Americans in my position.

There, I ran into another major obstacle that HDTV adopters are likely to encounter—cluelessness. When I asked the clerk, who appeared to be the owner or manager, about an antenna for HDTV, he said, "Oh, you have to have cable for that." I explained that except in a couple of test markets, no cable companies offer HDTV today, but that all of our network affiliates in San Diego are sending HDTV signals over the air. I don't think he believed me, but he grudgingly opened a catalog. I asked which antenna represented a medium-strength, amplified choice. He was dumbfounded. I asked about the CEA antenna-coding symbols. He pleaded ignorance. I left with a catalog and contemplated my next move.

Moving the mountain

The best way to test the antenna theory was to get physically closer to the broadcast tower. The TeraLogic folks reported that their amplified indoor antenna receives a signal from 20 or more miles away. I live closer than that to my local ABC and CBS towers. However, I live in a valley, out of the towers' line of sight. When signals reflect off of buildings and hillsides, engineers call it multipath interference, and it represents the biggest technical obstacle to HDTV reception in North America.

I couldn't move the mountain to eliminate multipath. But with my family's help, I loaded the Janus-based PC and monitor into the motor home, and moved us to the mountain. In the shadow of the broadcast tower, I immediately locked onto the ABC signal. I could even receive it without the antenna. But I still received audio-only from CBS. It appeared my quest for HDTV basketball was over.

On Monday, I phoned the CBS affiliate, KFMB. Station engineer Gary Stigall immediately recognized my situation. He indicated that KFMB had worked its way through numerous incompatibilities between the encoders and modulators on KFMB's side and the decoders and demodulators in specific consumer products.

Stigall related that RCA's DTC100—which, ironically, was being marketed to basketball fans in a $2500 bundle with a 32-inch monitor and an HDTV-capable DirectTV dish—had experienced a similar lack-of-picture problem the prior week.

Stigall felt relatively certain that PSIP was causing my problem too. The TeraLogic folks are evaluating this claim. I couldn't get confirmation of the story from Thomson, but director of government and public relations Dave Arland agreed that a number of such scenarios had taken place around North America. I even stopped by Circuit City, which was heavily advertising the DTC100, to see if they could verify the story. There I met another human obstacle to HDTV proliferation. Circuit City wasn't displaying the receiver, this genius said, because it was too hard to get it to work. Still, he was more than willing to sell me one.

As for me, I'm still mulling an antenna, because I figure this won't be my only HDTV trial. If TeraLogic can find a fix for the Janus board, I'll report in a follow-up story on our web site.

For now, I'll have to comfort myself with the knowledge that I watched a NASCAR race via an HDTV signal. Sadly, the cameras at the race had only captured NTSC resolution. You see, even if your HDTV receiver functions perfectly, there's just not a whole lot of HDTV programming to choose from today.