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Copyright © 2004 -
Information Today, Inc.



The Moving Picture: The DVD+RW "Just Press Record" Video Recording Format
Posted Jan 1, 2003 - June 2004 Issue Print Version     Page 1of 1
  

At my house, I have a twelve-year-old Magnavox VCR. It's not a premium model, and about two years ago, the remote control stopped working. I've tried new batteries. I've taken it apart a couple of times—the warranty long since expired—to clear the button terminals and reposition the rubber touch pads. Each time I took this tack, for some short time, it would work. But alas, it never lasted and now it's been almost two years since we've even tried it.


Friends ask why I don't just buy a new one. Without the remote, I have no menu access and no way to pre-program recording or even set the clock. But with a DVD player for watching movies, I don't use the VCR that much, and I can still get it to work fine for playing and recording VHS tapes by just hitting the buttons. And being "in the business," I can't help set my sights on a future all-digital, disc-based replacement.

Of course, mentioning such a device to friends usually elicits questions that inevitably turn the conversation to the technology I cover. By now, you'd think I'd have perfected a stock explanation of how DVD players and DVD authoring work that didn't lose my listeners in a quagmire of technology.

"The menus you see at the beginning of DVD movies actually take some serious programming code, and until recently have only been available in equipment that costs tens of thousands of dollars," I offer, to what seem to be unimpressed looks. "But the industry is moving so fast and now consumer-level authoring tools can do it too. It's really amazing."

No matter how much I expound on the intricacies and wonders of the technology, they don't seem captivated. Today, they just put a tape in their VCR and press play or record and never even think about the technology involved because they don't have to. How the tape heads read analog frequencies from magnetic tape hardly matters because, like my twelve-year-old VCR (remote or no remote), it just works.

Still, they listen with some mild interest because they like the idea of a future DVD player that will be able to record video, not just play it back. In fact, they usually ask when these player/recorders will be available at reasonable prices. Informing them that it's difficult to do technologically only gives the impression that it will take longer, and thus isn't worth giving much thought right now. Maybe I shouldn't tell them about how difficult it is.

And maybe I don't have to. The consumer electronics heavyweights (Sony, Philips, Ricoh, HP, et al.) in the DVD+RW consortium all recognize how important ease of use is, too. DVD+RW-based digital VCR replacements would avail consumers of all the flexibility, features, and ease of use of tape-based products, including putting in a disc, recording to it or playing it, and taking it out again, something hard drive-based PVRs can't do. (Panasonic's latest set-top DVD recorder, the DMR-HS2, which combines DVD-R, DVD-RAM, and a 40GB hard drive, is a notable exception.)

Enter the DVD+RW Video Recording Format, or DVD+VR Format for short. Even that name is a mouthful, but it's better than something like "DVD+RW real-time authoring format." DVD+VR is the technology that allows DVD+RW drives to burn video to disc on-the-fly just like tape-based VCR.

This is hard to do, I think to myself. First, the drives have to be fast enough to keep up with the stream of high bit-rate video and audio coming at it in real-time, no glitches, although that's not as serious a problem as it was a few years ago. They really need to support single-pass variable bit-rate encoding, without the benefit of a powerful computer CPU. They have to eliminate gaps between the recording blocks in order not to send relatively stupid, CPU-less, consumer DVD players into a search-mode abyss, all the while formally closing a disc so as to allow recording of other programs without erasing existing ones. They'll need to create instant menu bit-maps so users will be able to find the different video clips and shows, and otherwise navigate the disc, DVD-style.

That's not a problem for general-purpose computers, and consumer authoring applications like Sonic's MyDVD and MedioStream's neoDVD already support that. But CPUs in consumer electronics devices don't beget "reasonable prices."

And speaking of finding clips, these digital-VCR replacements need to support fast-forward and reverse search functions and that means predicting the future, in a way. Compliant DVD disc images contain Video Objects, or VOBs, which are effectively MPEG-2 files with little pieces of data added to help those not-so-smart consumer DVD players recognize and work with them as DVD-Video content.

For example, indexing information allows players to search at multiple scanning speeds. It's relatively easy to do a little buffering and insert the short-range indexing points for 2X fast forward, but it takes some more serious algorithm work to insert the faster fast-forward indexing points into yet-to-come video streams.

Tape-based VCRs can't edit recorded clips without overwriting them, but by leveraging DVD chapter marks and marking some as "hidden" for playback, the DVD+VR format effectively enables VR-capable player/recorders to play "cut lists." Authoring applications from Ulead and MedioStream already support this function with DVD+RW drives, enabling re-authoring of otherwise-finished DVD projects by recording in VR mode or by including original project information in a ROM zone on the disc. It's easy to imagine a DVD-based recording device that could hide commercials, but don't look for that legal red flag in any first-generation products.

Besides, it would probably mandate a hard-to-use interface and that wouldn't help with the "just hit record" crowd. I'll probably end up telling that crowd about it, though, because it seems like such a cool idea. I just won't say how difficult it is.



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