In the 34 years or so since I was introduced to computers there have been a few moments that really grabbed my attention, and that formed lasting memories. One was the first time I loaded up buttfish.gif on my 12 mhz. 286 with it’s shiny new Orchid graphics card, and saw 640 x 480 pixels of stunning 16 bit color. That was about 1988 or so. Another occured around 2004 when I was over at a friend’s house relaxing after dinner, and he opened up a window on his desktop. There was a spinning hourglass for a couple of seconds, and then the local newscaster was in that window delivering the 11 PM update. Live television in a window. That was very slick. Later that same friend was an early adopter of a sweet 24″ wide-screen monitor, which he hooked up to an ATSC tuner for over-the-air HD. That was even slicker.

Before long I had my own tuner, an ATI device based on their Theatre-550 chip hooked up to Comcast, running Snapstream’s Beyond TV as a front end. These types of tuners are a combination of television receiver and video capture circuitry. They receive and decode the incoming analog RF signal and send the frames to a digitizer, which converts them to digital and outputs them as an mpeg stream. With this combination of hardware and software I received 70 analog channels, and could do all the requisite DVR things like skip around and record. The quality was so-so, but not any worse than an older analog television, and it was right there on my desktop. I could watch breaking news as I worked on code or a document, record movies, all that good stuff, either full screen or in a window. Neato.

Then came the digital switchover. Suddenly the 70 analog channels that I had been able to receive became 23. Life was dark and colorless. ST:TNG could not be recorded. And thus it remained for some time. I stopped watching TV on my computer, and took to renting movies when I felt like it. DVDs always looked great on my Dell 24″ widescreen;  much better than those old analog TV channels, and who the hell needs them anyway? Sniff. More time passed, and I found myself opening my birthday present a couple of weeks ago, and there inside the box was a Silcondust HDHomerun.

Since the rest of this post isn’t going to necessarily wax all sweetness and light about digital cable on the PC, let me say one thing about the HDHomerun up front: good God, what a cool little device this is! If you aren’t familiar with it, an HDHomerun is a little unit about the size of a 4-port switch. It has two coaxial connections for signal inputs, an ethernet port, and a power brick. You connect the coax from the cable provider, patch it to your router or a switch, and plug it in. Install a little well-written software on your PC (native Windows 7 64-bit included) and voila! You now have two QAM-capable HD tuners streaming beautiful 1080 HD (and whatever else) over the network to whatever QAM-capable front end you want to use. I’m using Windows Media Center, which at least in the Windows 7 version works very well with clear QAM. Wait, what? QAM? What is that, you ask? It sounds like an acronym for a gastric disorder. In fact it is not. It merely causes gastric disorders.

QAM stands for Quadrature Amplitude Modulation, and all the technical details that I don’t understand aside, it is a protocol by which streams of bits are transmitted between the cable company’s digital head end, and the QAM decoder in your set-top box, cable-ready widescreen TV, or HDHomerun. There it may become beautiful HD video, or still-pretty-decent SD video, or information such as program-guide entries, channel assignments, programming metadata, etc. Since the average coaxial cable connection is a very fat pipe indeed, squeezing nearly 40 megabits/second out of a single 6 mhz. slice of its over 750 mhz. of bandwidth, the protocol is continually evolving to add additional services. In fact, one of the reasons cable companies are eager to go digital is that the old analog channels take up a big chunk of that 750 mhz that could be used for other stuff.

Unfortunately, tuning in to all this wonderful stuff is a little like sitting in front of my Dad’s old tube-driven Hallicrafters spinning the shortwave dial, circa 1970. You’d hear lots of interesting things, but never really know where they came from, or why, or even necessarily how to find them again if you wanted to. In the digital cable world the set-top box, or STB to geeks, receives all this digital information and uses it to organize the channels, construct the program guide, send and receive commands, etc. Most importantly, it decrypts the channels that have been scrambled by the cable company, which might include all the channels, or just some of them, wholly depending on where you live and what the local cable operator chooses to do. The FCC says that they have to send the digital streams for network and some other feeds “in the clear” so that devices like the HDHomerun and Digital Cable-ready televisions can receive them, but that might mean as few as a dozen channels on some networks.

If you buy a digital QAM tuner card or device and hook it up to your cable system, then scan for clear channels, and you’re lucky like me, you may have as many as 120 or so come back in a list. Each will be identified by a virtual channel number, potentially a guide number, and a callsign or identifying string of text. The virtual channel numbers consist of a primary channel and subchannel, for example, 65.4, which is currently the History Channel on my system. For stations with multiple feeds you might find them snuggled in next to each other within one primary channel. If the station is one of the old-line networks then it has probably been assigned the primary digital channel that corresponds to the traditional analog assignment in that area. For example, WABC in New York has been channel 7 for years. On the Comcast digital network the four WABC feeds are currently 7.1, 7.3, 7.5, and 7.7. When these channels are presented to the viewer by the STB it hides them behind the guide numbers, so WABC is at guide channel 7, where it has always been, while the HD feed at 7.7 is mapped up into the 200’s with the rest of Comcast’s HD lineup.

This mapping capability allows the cable company to move digital channel assignments around without affecting the programming guide, and unfortunately for the PCTV enthusiast that’s exactly what they do. In the short time I have had my HDHomerun Comcast has made changes to the channel assignments twice, throwing my carefully edited channel mappings in Media Center out the window. But if the channel assignments change, at least it should be easy to pick up the new location by scanning the callsigns, right? I mean, WABC is WABC. The problem is that once again the STB has access to channel metadata that the tuner and Media Center do not, and it uses this metadata to make the callsigns understandable. Without this information, it’s left up to you to figure out that WABCDT2 is the WABC HD feed, that WPIXDT is the ION HD feed, that WLVTDT4 is the HD feed for the local public television station, etc. And if you take the time to do that, editing in the correct descriptions for all the available channels as Media Center allows you to do, and then have to rescan because the assignments changed… well it sucks, let’s put it that way.

It would be nice if the cable companies would assign stable digital channels, but for whatever reason they don’t. And I don’t mean to imply that the shifting is done for spite. I applaud Comcast for sending nearly 120 clear channels in my area, and in each of the last two shufflings I have actually gained new channels. So they have their reasons, but it still makes setting up and maintaining digital cable on your PC a real challenge. Not that I doubt the overall antipathy, or at least apathy, that cable providers feel toward component digital tuners. What they want is to rent you a set top box, which gives them pretty close to end-to-end control over the content and the presentation. What the rest of us want is for them to act a little like the old networks, that broadcast in the clear and for the public good to at least some extent. The FCC also wants this, and has required the cable companies to support the Cablecard standard, which allows you to plug a decryption module into a digital tuner and receive all the encrypted content without a STB, and without any two-way services or programming guide. Still the cable companies support Cablecard only half-heartedly, and the fact that there are Cablecard-ready PC tuners on the way is unlikely to cause any smiles to break out at Comcast.

The cable providers have been in an enviable position for some time now, with municipally-granted monopoly markets that companies like Verizon are only now beginning to break in to. Within the fuzzy embrace of those regulatory monopolies they have built a truly impressive hybrid fiber/coax network. As I mentioned above they have a tremendous amount of downstream bandwidth in that pipe, and over time they will have many opportunities to fill it with premium services. My own feeling is that they should send all the non-premium SD and HD feeds in the clear, with stable channel assignments. Let’s face it, most of these channels are commercial-choked crap these days anyway. By sending the straight video in the clear companies like Comcast will only increase the number of screens in the average consumer household on which their content is playing, and they can include advertisements for their premium services within those content streams.

Whether this will ever happen I don’t know, but one thing I am quite sure of: over time there will be more and more alternatives to the cable content feeds. Driven by competitive pressure they have steadily increased the bandwidth and quality of consumer level connections. I get 20 mbps downstream here, and 2 mbps up. Not long ago I watched every episode of the PBS series “Carrier” in HD, using Microsoft’s Internet TV service through Media Center. The cable providers can’t close down the IP pipe they’ve opened, and that pipe represents competition. Perhaps, over time, that competition will spur them to become more open and less defensive about what they consider to be the proprietary parts of their content stream. We’ll see. In the meantime setting up a digital cable-ready PC is going to remain something for enthusiasts with more time and patience than sense, and that includes me.

Leave a Reply

Your email address will not be published. Required fields are marked *