For Information
April 22, 1996

NTT Develops Multimedia Videoconferencing System that Enhances the Impression of "Being There"
- Provides a natural, seamless videoconferencing environment -

Nippon Telegraph and Telephone Corporation (NTT) has developed the provisionally named Panorama videoconferencing system, a multimedia system that eliminates the sense of being physically separated from other users and provides a natural, seamless environment for conversation and work collaboration.

With the system, which uses clear, life-size images, people in separate locations can enjoy a heightened feeling of sitting around the same table with each other. Efficient meetings involving collaborative tasking are made possible by seamless data-sharing and harmonized sound and images.

In maximizing the atmosphere of sharing a common space, the system is expected to set the standard for videoconferencing environments of the foreseeable future.


I. Development Background

Individuals as well as businesses are increasing their use of network-based multimedia applications. In response, major task of technology developers has been the creation of a multimedia environment that removes the user's consciousness of interfacing via a network and network system.

NTT, under a corporate-wide program aimed at developing what it calls Visual, Intelligent and Personal (VI&P) communications services, has been harnessing its broadly based technologies in a range of comprehensive tests that have confirmed the integrated performance of network facilities and applications. The multimedia videoconferencing system announced today is one result of these VI&P tests. By creating an environment that makes users feel they are in the same room with remotely based participants, the system takes image, voice and data transmission and display technologies beyond conventional limits.

II. Technological Points

The new system incorporates four types of multimedia and technologies for their integration, including large, 110-inch super high-resolution displays, a multi-channel sound image localization system, the COGENT collaborative tasking environment, HDTV coding and transmission, and an ATM (*1) transmission system.

1. Natural images (large, super high-resolution display)
The new system uses 110-inch (2.4m width x 1.3meter height) displays and proprietary fine-imaging technology that achieves four times the pixel density of a normal HDTV projector. The result is extremely detailed life-size representations of other users. The high density of bright images eliminates the needs to darken the meeting venue or sit in specific positions, freeing the participants to concentrate on the meeting.

2. Sound image localization from remote locations (multi-channel sound image localization system)
Multiple microphones are positioned on the ceiling around the conference tables and speakers are positioned to create an audio sense of each participant's actual position in terms of left/right and depth. Sound location is also harmonized to the position of the person's image shown on the display. Sound is transmitted at 20KHz for CD-quality reproduction with exceptional clarity thanks to technologies that eliminate howling and noise. Since the microphones are not visible, the person speaking is not conscious of them and is able to move around the conference room freely. The position of the remote person's image and the localization of the reproduced voice are the same, ensuring a natural-sounding environment.

3. High-effective collaborative tasking environment (COGENT)
COGENT was developed to support effective collaborative tasking and information sharing in videoconferencing situations. Each participant has access to a networked PC for data sharing and free access to the Internet and other networks. NTT is currently developing technology for projecting data on the system's super high-resolution display, which will allow data to be displayed along with multiple images of data and users.

4. High-definition image transmission (HDTV coding and transmission)
The system's HDTV coding and transmission device is of the same quality as equipment designed used by broadcasting studios. It can transmit high-quality HDTV signals at 150Mbps in either ATM or STM (*2) formats. HDTV image signal sub-band encoding (*3) at 1.2Gbps compresses images to about one-tenth their original size with no loss of quality. The system also supports 150Mbps transmission.

Testing took place at three locations: two within the NTT Musashino Research and Development Laboratories and one at the Yokosuka Research and Development Center, approximately 100km away from the former. The broadband ATM-transmission network linking these sites realized high-quality image communications with no sense of the distance involved.

III. Future Plan

Hereafter, NTT will continue verifying functions that need bring an even greater sense of immediacy to videoconferences, as well as upgrading the system for commercial applications.

IV. Terms

*1) ATM (Asynchronous Transfer Mode)
ATM combines the advantages of packet switching and line switching to transmit multimedia (including sound and image) data at high speed in real time. Information is divided into small blocks (53-octet packets) known as cells with an attached header that indicates the destination. Transmission is accelerated by simplifying the protocol used by the network.

*2) STM (Synchronous Transfer Mode)
In contrast to ATM, STM transmits the synchronous digital hierarchy frame in virtual containers divided into time slots, into which each channel's signals are inserted and transmitted. STM systems work with identically sized units of information. It is particularly suitable for constant information traffic networks, such as telephone services, in which the transmission signals are almost equal and traffic conditions can be specified.

*3) Sub-band encoding
Under the sub-band method, signals are divided into multiple bandwidths, and encoded in specific frequencies.