San Francisco, October 13, 1999In first-ever demonstrations of real-time multichannel audio over the Internet, 5.1-channel Dolby Digital audio was successfully streamed from Montreal to New York City during the recent convention of the Audio Engineering Society.
Under the auspices of the Society's Technical Committee on Network Audio Systems (TCNAS), live performances by the McGill University Swing Band in Montreal were streamed to the 300-seat cinema at the Cantor Film Center of New York University (NYU) on September 26. Attendees experienced the same 5.1-channel surround sound provided by movies in theatres, DVD, DTV broadcasts, satellite transmissions, and other media that feature Dolby Digital encoded audio.
"Dolby Laboratories is pleased to have supplied equipment and technical assistance for this pioneering experiment," said Steve Vernon, Dolby R&D Group Leader. "We're particularly excited to see that the Dolby Digital transmission performed flawlessly in spite of significant variations in available bandwidth."
Among the applications envisioned for new Internet technology like that demonstrated is to enable people in entertainment, business, education, or research to collaborate live online. The underlying software making it all possible was developed at McGill University by a team that included several members of the TCNAS.
The demos in detail
While the primary purpose of this demonstration was to investigate the high-quality audio potential of high-speed Internet connections such as the Canarie-2 (Canada) and Internet-2 (U.S.) backbones used for the demo, a live video feed was also streamed simultaneously and projected onto the movie screen at the demonstration site.
The 5.1-channel sound mix was prepared at McGill University as a 48 kHz, 16-bit program, which was then Dolby Digital encoded using an off-the-shelf Dolby DP569 encoder unit at 640 kbps. The Dolby Digital bitstream was encapsulated for interconnectivity purposes in an AES/EBU stream at 1.5 Mbps, which was then sent over the high-speed Internet link. Video was transmitted at about the same data rate using Cisco's IP/TV system with MPEG-1 compression. At NYU, the audio signal was decoded from Dolby Digital back to PCM using Dolby's DP562 decoder unit.
The first of four demonstrations used a 23-second buffer against network congestion, while the final three used a far less conservative three-second buffer. No effort was made to limit network activity to guarantee available bandwidth, except to disable the incoming Usenet news feeds at both universities during the first three demonstrations.
During the final demo, the NYU news feed was switched back on, subjecting the streaming program to intense competition for bandwidth. Nevertheless, at no time in any of the demonstrations was the Dolby Digital sound perceivably interrupted.
To check for anomalies that might be introduced by the streaming process, digital recordings of the streamed audio made at the NYU site will be compared to recordings made simultaneously of the live performances at the McGill venue. The Committee also plans to experiment with multichannel transmissions of uncompressed 96 kHz, 24-bit linear PCM audio at 13.8 Mbps.