Sunday, May 29, 2005

Powering On

Welcome to my new "What's on HDTV?" blog.

What's the occasion? I just got a cable box that records HDTV (as well as standard-def) programs. For the first time I have the ability to watch HDTV when I want to, not when the programs happen to be on. The way my life goes, that ability to timeshift makes a huge difference.

I've been able to watch HDTV for almost a year and a half on a Samsung 61" DLP television, by means of my earlier cable box, which lacked a DVR (digital video recorder). But I found I almost never went to the trouble, preferring instead to watch stuff I'd recorded off DirecTV. I have a DVR in my DirecTV receiver, although it receives, records, and outputs only standard-definition programs. I guess I'd rather take control of my viewing schedule more than watch HDTV. But now I can do both.

For those who are new to it: HDTV is high-definition television, which is digital, not analog. There are two formats, 1080i and 720p. 1080i presents a 1920x1080-pixel, interlaced picture (first the 540 odd-numbered scan lines, making up the first "field" of the "frame," then the 540 even-numbered lines in field two). 1080i is usually broadcast at 30 full frames per second (60 fields/second).

720p uses a 1280x720-pixel frame, scanned progressively such that all 720 scan lines are shown at once, usually at 60 full frames per second. Because of progressive scan, 720p is better for sports and action. Because it has more static detail per frame, 1080i is better for pictures without a lot of fast movement.

If you have an HDTV, you can watch (usually) one or the other, not both. The one which is not the TV's "native" scan rate has to be converted to the other. My Samsung "does" 720p natively and downconverts 1080i to it. (Actually, that point is moot. My cable box is set to transmit all HDTV signals to my TV at 720p.)

1080i and 720p both have a widescreen 16:9 aspect ratio. Standard-def TV uses the squarish 4:3 aspect ratio we are so familiar with.

I route the HD signal from my cable box to my TV using a three-headed component video cable, also known as YPbPr since the luminance (Y) and the two chroma difference signals (Pb for "blue" and Pr for "red") are on separate lines.

The audio goes to my A/V receiver in digital form, when available, and in stereo analog form otherwise. The receiver detects the digital audio when present and uses it; else it uses the stereo analog signal.

Sometimes, but not always, the program I'm watching has full-fledged Dolby Digital 5.1-channel audio. Sometimes it uses fewer digital channels. And sometimes, as I say, the only audio is old-fashioned analog stereo.

So the hookup is nontrivial. Remember when all you had to hook up to watch TV was an antenna and a power cord?


My new cable-box-cum-DVR, as provided by Comcast Cablevision here in Baltimore County, MD, is a Motorola unit which looks just like the one the cable guy took out, the one without a DVR. Considering the connections are all the same as before, I'd like to say the install went without a hitch. But it didn't.

First, the installer put the coaxial digital audio output cable in the wrong little hole: no sound. I soon found the problem and fixed it. Likewise, at least one of the three YPbPr connectors was misplaced: everything was blue. The installer was in a hurry to get me to sign off anyway, but I woudn't. He fiddled with the connections, and everything was fine.

The remote control, for the first time, is pretty much state of the art — read, lots of buttons. It's programmable; I haven't tried that yet. Controlling the complex onscreen functions for the cable system and for the DVR has been easy enough so far.

One of these functions is the ability to display a program list by channel or by time for just the channels that offer HD material. That's nice ... except that the Comcast SportsNet standard-def channel (7) is listed instead of the Comcast SportsNet hi-def channel (200). Which means that when I select a program, I get the SD version, not the HD. Bummer. All the other HD channels seem to be listed OK. I assume the mixup with Comcast SportsNet is something Comcast has to fix at their end, not a glitch at my end.

And that's my only real complaint to date, at least insofar as things Comcast has any control over.

But my other gripe is how hard — even with the dedicated HD program guide — it is to find our what's on in high-definition. And the cable box's HD guide does not really tell me which programs are actually being broadcast in hi-def ... just what's on the channels that sometimes do hi-def.

Add to that the fact that some programs mix and match. NBC recently broadcast the Kentucky Derby and Preakness Stakes in high-definition. Yet several of the cameras were lo-def, upconverted, while the main shots were true-hi-def. Played havoc with my eyes, which thought they'd gone out of focus whenever a lo-def shot appeared.

Compounding the confusion is the fact that some hi-def sources — my local Public Broadcasting System affiliate, for instance — do not simulcast HD with the SD schedule. The two schedules are completely independent, and the HD schedule is not listed in either the national or the local-newspaper TV guide.


And, oh, by the way, I'd better mention that HDTV when done well is magnificent. I've watched a Baltimore Orioles baseball game and a D.C. United soccer game on Comcast SportsNet. Both offered stellar picture and sound. Crisp details. Vivid colors. No blurring when things are in motion.

As much as this improves baseball, the benefit is greater for soccer. The camera usually has to pull back away from the action to keep from having the ball exit the frame. That makes the players and their numbers tiny and hard to recognize, with lo-def. With hi-def, the problem is ameliorated, plus the wider picture shows more of what's going on. It's still hard to see the numbers on the players' backs, but that's more my eyes than the TV signal. And being able to recognize the players offsets it quite a lot.

Unfortunately, the commercials and sports updates are lo-def ... and sometimes the engineer-in-charge doesn't properly "pillarbox" them in a 4:3 box centered on the 16:9 screen, so people and objects get stretched horizontally. And that just compounds the lack of detail, making me realize just how nice the hi-def picture really is.

But, enough for now. In the future, I'd like to report on my HDTV experiences, with an emphasis on what's on, how easy it is to find it, and what its actual technical quality is.

By technical quality, I mean things like a classical music concert I saw in passing on one of the HD cable channels (I forget which one). It looked fine ... until the camera started to move, at which point everything grew blurred. I suspect the culprit was either too much digital compression or some other ill-conceived form of signal processing, such as maybe upconverting the video from some lesser scan rate. There was no blurring on either the soccer or the baseball, so I know it's not my imagination or my equipment that's at fault.

I realize it's a bit early in the changeover process from analog lo-def to digital hi-def to expect perfection. But it's not unlikely, I hear, that Congress will pull the on analog TV at the end of 2006. Soon, a lot of us will start expecting HDTV to look as good as it can, and won't be willing to put up with the equivalent of big-game hunting to find out, "What's on HDTV?"

2 comments:

Richard Muller said...

Hi Eric,

I just stumbled onto your blog, compliments of Google. (I was looking for the MPTHD schedule.) I'm also a retired programmer and a neighbor, sort of: I live in Finksburg.

You did a great job in exposing the technical intricacies of HDTV. Thanks for publishing it
(and keeping available for almost four years.

Best wishes,
Richard Muller
RLMuller@USComputerGurus.com

eric said...

Thanks for your kind words, Richard!