Video By The Numbers

Our veterinarian once told us that our sainted old mutt, Burst, could only possibly learn the names of six or seven of her chew toys, with the clear implication that the arrival of toy number eight (the rubber cheeseburger) would effectively erase all memory of toy number one.

If it held true for humans, this neurological aberration could become really worrisome in my professional life. I've already got an alarm code at work, ATM PIN numbers, the car alarm and the phone credit card. There's the voicemail retrieval code, Social Security number, Frequent Flyer numbers and a combination lock on my luggage. Truth is, when the numbers start flying fast and furious, my eyes start spinning like a slot machine.

And it's getting worse. Lately, I've been seeing a lot more new numbers -- numbers I never knew I'd have to know.


When I trained in analog video, I memorized a few key digits: 3.58, the color subcarrier frequency in MHz; 7.5 IRE units in the pedestal; and 66 minutes of tape on a 1-inch reel. There were 13 equalizing pulses in the hammerhead and, on a good day, five-and-a-half pulses before the scanner dropout. To "86" a scene meant to erase or delete it, and "take five" meant we should disappear for 20 minutes.

But video moved to computers, and there were new numbers to learn, like 640x480, the nominal pixel count of the digitized video raster, and various frame rates including 29.97 frames per second ... who knew that the frame rate was open to negotiation?

Within a relatively short span, the digital video revolution started flinging a whole heap of new numbers at us. Standard definition CCIR-601 was 720x486, still at 72 dpi, and most often 8-bit, although dynamic rounding might yield a 10-bit equivalent. A 4:2:2 stream typically runs at about 50 Mbps, but don't forget the 16-bit audio at a 48,000 Hz sampling rate, not the old 44.1 KHz. Then there's DV... slightly different numbers. And MPEG-2 for DVD. Everyone ready for 1080i and 24p?

The eyes glaze over and start to spin once more ... three lemons.


Whining about technology changes is never attractive, and it's even more ugly when the whined-about changes actually represent the very best attribute of computer-processed video: resolution independence. By the inherent nature of software manipulation, pixel counts, bit depths and frame rates represent a kind of virtual resolution. It's up to the software application to determine the dimensions and specifications of the video it processes. That's how feature-film effects are composited on Dell desktops, for example.

But when new numbers keep cropping up nearly every month, and new file formats, codecs and compressors, too, I get progressively more baffled by the differences between 720x486 and 720x534, for instance.

Now, I've never claimed to be the brightest fixture in the grid, and when something concerns or confuses me, I occasionally remember to consult those whose business it is to know the answer. So I called Steve Kilisky.


Steve heads the Adobe product team responsible for AfterEffects, and I know from firsthand experience that you could run a dime-store postcard through AfterEffects and animate it for an IMAX feature, more or less. So Steve would be the authoritative word on the numbing avalanche of numbers I was so distressed about.

"Just when it all makes sense," said Steve, "a new format appears on the horizon that confuses everyone who previously thought they understood everything." As a result, he explained, users expect AfterEffects, like other desktop video applications, to handle pretty much anything they throw at it.

"That was one of the main reasons we added interpretation rules in AfterEffects 4.1," he said. "There are a lot of things to pay attention to, and this is how we can help.

We try to remove the burden of the user having to know this information, or having to continually look it up in the manual."

But how much is too much? I've scrolled down the long list of Adobe-supported formats, and I can't believe some of these get used more than twice a year. Steve agreed: "I think they go beyond the needs of 90 percent of the users."


The AfterEffects team prides itself on its ability to respond to new formats, according to Steve. The Panasonic Vari-Cam, a high-definition camera with a variable frame rate, motivated several AfterEffects users to request support for its unique format. "When shooting in 24p mode, it uses a fairly unique pulldown scheme," he said. "AfterEffects' 'Interpret Footage' mode gives you a great deal of control over pulldown mode, reverse telecine, and so on," he said, adding that accommodating this new format was "... not a hard thing to do."

"On the software side, most of these are fairly straightforward," Steve said. "It's just a matter of us implementing it."

Of course, I couldn't help but ask the obligatory HD question. "I hear less and less about 640x480 these days," he said. No, he hasn't seen the high-def marketplace explode, although he says that more and more people seem to be using the standard definition 16:9 format. HD, he believes, is something everyone wants to be ready for, but few can afford to work in.

Still, HD formats are no big deal for resolution-independent software like AfterEffects, according to Steve. "When high-definition first became a buzzword, people were asking, 'When will AfterEffects be ready for HD?' And we're like, 'It's been ready for five years.'"


It's not just about pixel counts, though. Thanks to the wide variety of proprietary hardware and software products used in production, digital video applications need to navigate the rocky terrain of codecs and file formats, too. It's hard to say how many combinations of file types and compression algorithms are supported by Adobe, but the number is huge... and growing.

Steve acknowledged the role of Murphy's Law in video production. "If we were to drop one of those file formats tomorrow," he admitted, "you'd have a client come and ask you for it. No question." Adobe did actually delete a file format recently; the company decided to abandon Amiga IFF's in favor of Alias|Wavefront's Maya IFF file format, primarily because the latter needed the ".iff" file extension.

But it's adding, not subtracting, that keeps Adobe the king of compatibility. "We don't spend any time thinking about which ones we can eliminate," Steve said. "It's really just trying to keep up with the new ones."


In the end, I seem to have adopted a need-to-know approach to this numerologist's nightmare: If it's a number I need to know, I'll try to remember it. If it's just an informational tidbit, well... sorry, but that little cipher might just push one of my other numbers right out of my head. What if I lose my house number, or the pizza parlor's phone number? Thanks anyway... I guess I'll just have to look it up.

And by the way, my old dog actually learned the names of well over 15 of her toys without forgetting a single one. I guess there's hope for me, too.