Dolby Digital downloads head toward home theater   9/22/1999

By Nathaniel Wilkins

September 22, 1999 -- Fast-forward a few years. Your Internet connection is fast, really fast. It's well over 100 times quicker than what you currently experience with your 56k modem. You're ready to download some serious entertainment -- I'm talking DVD-quality video and surround sound. And you're not going to sit around waiting for it. You expect it to "stream" into your living room.

The members of the American Engineering Society (AES) Technical Committee for Networked Audio Systems have also gazed into the crystal ball. And although the technology is still in its formative stage, they've organized a workshop/panel on and demonstrations of multichannel audio distribution. The panel will take place at the AES convention, which is to be held in New York City's Jacob Javits Convention Center on September 26.

Following the panel will be demonstrations at New York University's Cantor Film Center, which features a Dolby Digital 5.1-channel sound system. Of course, will be there. NYU dancers will perform to music (provided by McGill University's concert jazz band) and video that is transmitted simultaneously from McGill in Montreal, Canada.

A multichannel (four-speaker surround sound and bass) audio signal will be sent from McGill and streamed to NYU across a high-performance network that is managed in Canada by the Canarie corporation and in the United States by the Internet 2 corporation. According to NYU's Robert Rowe, the project manager and tech guru on this side of the border, folks in both countries have been working with those corporations for months planning this event.

The following chart shows the flow of the audio data.

Live -- without a net

Part of the challenge (and the significance) of this event is that it isn't merely a controlled lab experiment. That is, the data will not be traveling on a single network with a guaranteed amount of bandwidth dedicated to it. To the contrary, says McGill's Jeremy Cooperstock, technical lead in the coordination of the event, "someone could start a huge FTP transfer and eat up our bandwidth," thereby endangering the entire demo.

The original plan was to demonstrate two streams using different data-transfer rates. The most bandwidth-costly stream was slated to be a 15 Megabit per second uncompressed stream of 5.1-channel audio data. That's a ton of data pumping through the pipe at a rate around 300 times faster than that of a 56k dial-up connection. Unfortunately, the audio decoder, manufactured by a British company, wasn't working at last Sunday's rehearsals. As a result, it's likely that this aspect of the project will be scrapped for now (though you can expect to hear more about it from when it does happen).

This rate will probably be widely available to private homes in the next generation of networking. As a matter of fact, on September 13, Ken Kutaragi, president of Sony Computer Entertainment announced that the company plans to distribute digital movies online in 2002 or 2003, saying, "We see big potential in the household distribution of video games, films and other content via broadband cable lines." Films would be downloaded to Sony's next-gen console, PlayStation2, which will feature a DVD-ROM drive and full A/V capabilities, including an optical digital audio output. No further details are available at this time, so it's unclear what data transfer rate would be required to accomplish to this feat, but it does appear that the content will stream.

Sounds like a success

Happily, the second, less bandwidth-hungry stream is on track. It worked just fine during Sunday's rehearsal, prompting NYU's Rowe to say, "We were pleased, it sounded really good and went well." That stream consistedof 5.1-channel compressed Dolby Digital audio from McGill's jazz band to NYU, where it was decoded and broadcast over the Cantor Center's sound system. The data transfer rate was 1.5 Megabits per second, about 30 times faster than that of a 56k dial-up connection.

The video stream is MPEG-1 format (VHS quality) and requires an increase of 1.5 Megabits per second in the transfer rate. The video is sent separately on the same network and resynced with the audio when it reaches NYU, thereby providing a complete entertainment experience.

The system uses a 30-second buffer, which allows for glitches and variations in transmission speed and enables the viewers to perceive a steady, continuous stream. The buffer also provides a window during which the audio and video can be resynced at NYU. The total transfer rate required for this demo is about 3 Megabits per second, a level of performance that's well within the reach of cable modems and other emerging consumer technologies.

Part of the purpose of this demo is to gauge the quality of high-bandwidth audio and video streams. Accordingly, in an attempt to monitor any dropouts that might occur as a result of buffer under-runs, the show will be recorded at NYU and later compared to tapes of the same event made at McGill.

Race to rule the 'Net

Those of you eagerly anticipating the day when your computer will be able to deliver hi-fi home theater should be psyched by this demo. It proves that the technology is available now -- and it's not an isolated event.

A few weeks ago, Research TV and Sony demonstrated an HDTV stream sporting stereo audio. According to Research TV's Susan Brandt, the stream between Stanford University and the University of Washington was numbingly fast (270 Megabits per second).

What's more, it was reportedly done over an open Internet 2 connection. A press conference and second demo at the University of Washington next week will address the disbelief in many quarters regarding this claim. A stream at 270 Megabits per second is tremendously fast, but who knows when you'll be able to receive at this rate in your home?

You can be sure that we'll keep you up to date on the race to claim the speed title and the brave new world of downloadable hi-fi movies. Look for our coverage of the AES convention next week.