Hi-TV Makes Sending Video Over ATM Practical and EfficientOrly Stettiner
Video technology is dynamic. It seems to be in constant motion. Today, with the help of wide area networks, video is moving farther and faster than ever before.
Shows produced on location can have their film dailies processed in Hollywood, then transferred back to them over a wide area network in time to screen before the next day's shoot begins. To meet the impossible turnarounds of episodic television, dailies can now be transferred over standard broadband networks -- as they come off the telecine -- to the editorial team across town.
Producers naturally want to hire the best artists, animators, and visual effects compositors, wherever they might be in the world. With the ability to transfer shared video resources between facilities, creatives can work in a collaborative way as if they were part of one "virtual" facility.
On the broadcasting side, the competitive nature of the business has given rise to the use of wide area networks for back-hauling news footage from the field, for sending live feeds from sports venues, and for feeding local features to the network in time for the evening news.
After color correcting HDTV resolution images, an Inferno artist no longer has to wait while overnight couriers deliver the screening tapes. Despite the fact that high-definition video frames can hold megabytes of data, approvals can be obtained quickly by transferring the file over a network to the commercial producer.
This dynamic process -- where video moves easily from conception to contribution to distribution -- is intensifying in the DTV era as broadcasters and producers prepare to meet the increased demand for compelling, high-caliber content, especially for their HDTV channels. Waiting for dubs to be made and tapes to be shipped stalls the forward momentum of a creative project. And, back-haul via satellite involves exorbitant fees, provided a transponder is available when you need it. In this increasingly time-challenged, productivity-driven business, it's not difficult to see why producers, broadcasters and artists want to send their video over high-speed broadband networks.
ATM technology was designed to facilitate the transfer of video, as well as voice and data, over high-speed, broadband, fiber optic networks. ATM's approach is to organize the video into packets of data which are then routed over the network to the destination site for output to video tape machines, hard drives, or servers.
However, the switched packet approach often presents a challenge to the transmission of video which by nature needs to stream without interruption. Also, ATM multiplexers and network management equipment are not generally optimized for video because market demand has historically centered around the transmission of conventional data.
Video professionals that want to manage the transfer of video over ATM networks face a minefield of problems. First is the interoperability questions associated with devices from different manufacturers. There are also issues with systems that have not been designed to work with real-life ATM networks, which tend to impose imperfections such as cell losses, bit errors, and cell delay variation ("jitter"). Add to this the fact that network providers have historically offered only a single service – for example a provider might offer realtime transport of compressed D-1 or non-realtime file transfer, but not both – and most TV facilities will potentially have more than one application requiring more than one service.
With its new Hi-TV technology, ECI Telecom offers a solution to the difficulties inherent in sending video over switched broadband networks. Optimized specifically for high-quality video, the compact Hi-TV system integrates: realtime video compression and decompression, and ATM adaptation, multiplexing and network termination.
Hi-TV also supports a broad range of video, data and voice all types of communications over public networks (including , video, voice, and data), and thus, within a single box, can provide solutions for a range of applications within professional television and video facilities. It accepts direct input of CCIR-601 270 Mb/s video, AES-EBU digital audio, compressed SDTV and HDTV streams (in DVB, ATSC and SDTI formats), as well as data files; and it supports TI/EI circuit emulation for voice services.
After performing necessary compression, multiplexing, and network adaptation and interfacingmanagement functions, it outputs single or multiple streams of video using the ATM network protocol. ATM signals may be transported over high-speed and fiber optic networks at a variety of data transfer rates including: 34 Mb/s (E-3), 45 Mb/s (DS-3), and 155 Mb/s (STM-1, OC-3).
Hi-TV's companion Control and Management Application Software (which runs on Windows NT computers), handles a variety of tasks including tracking the status of transmissions and verification of delivery; the set-up and recall of transmission session parameters, such as bitrates, compression types, and GOP (group of pictures) structure; as well as troubleshooting and security. When both sender and recipient are using the Hi-TV box, the process of transferring video over a public broadband network is as easy as making a telephone call or sending an e-mail.
A Promising Market For Telcos
If the network service provider offers a pay-as-you-go, or dial-up bandwidth-on-demand service, then users only pay for the bandwidth or connection time consumed. Through its integrated forward error correction, clock recovery, and dejittering mechanisms, Hi-TV makes using cost-effective, bandwidth-on-demand services for sending video easier to manage, with more reliable results.
Among the major telecommunications companies testing and evaluating Hi-TV, Since October of 1997, MCI Communications Corporation, in Washington, D.C., has been successfully testingtested Hi-TV since October 1997 for a new TV-Over-ATM Project, taking place in Fort Lauderdale, Florida. MCI Worldcom'swsMCI's test involved using Hi-TV to compress studio-quality TV in realtime using the MPEG-2 4:2:2 Profile @ Main Level and transporting it over a nine-node coast-to-coast ATM network comprised of ATM switches from various vendors.
During the test, inordinately-high levels of cell loss and cell delay variation were intentionally introduced into the ATM network. But, Hi-TV proved its ability to accommodate adverse network conditions, and provided smooth, studio-quality TV output. MCI's fast-growing portfolio of advanced data, Internet, and IT services now accounts for nearly one-quarter of its $19.7 billion in annual revenue.
In a real-life application, MCI used the Hi-TV system to carry the first live high-definition broadcast of a baseball game -- the 1998 opening day game between the Texas Rangers and the Chicago White Sox on March 31. The HDTV signal of the game was produced by LIN Productions, and was carried by MCI’s broadband ATM network -- using the Hi-TV system as the ATM network interface device -- to WHD-TV, a high-definition test station in Washington D.C. From there, the broadcast was transmitted to a special HDTV demonstration that was held at the U.S. House of Representatives' Rayburn Office Building.
By utilizing Hi-TV systems, the major telcos will be better-equipped to provide video transmission services. ECI Telecom incorporated features into Hi-TV that permit service providers to obtain a customer's network usage, for billing purposes, by remotely accessing their Hi-TV unit's database via the network.
Increasingly, major telcos have come to realize that video represents a promising growth market for their services. As the field of service providers grows, increased competition will promote greater choice and drive down the cost of services. Enhancing the growth potential is DTV broadcasting, and HDTV in particular. Hi-TV technology will allow instantaneous digital television feeds and program distribution over the major telco's broadband ATM networks.
With Hi-TV, it's possible to stream, encode, and decode live compressed video, or to send full-bandwidth compressed D-1 quality video as a data file, from one server or hard drive to another. Specifically, Hi-TV's integrated CODEC supports three video compression modes that can be selected by the user at call setup:
Hi-TV also accepts pre-compressed video sources including HDTV/ATSC, SDTI and DVB (ASI/SPI) as well as other pre-compressed data streams. SDTI transport will support four streams at real time or one stream at four times real time.
Support for Real World Applications
In the contribution-distribution model, broadcasters can use Hi-TV to back-haul a feed from a sports or special events venue to the studio. And, since Hi-TV encodes and streams SDI-quality (525/60, 625/50) or HDTV-quality video feeds according to standard MPEG-2 compression schemes, DTV broadcasters can use Hi-TV to pass the feed from their studio-to-transmitter site.
For broadband file transfer, if both sender and recipient plan to keep the video as a data file stored on their hard drives, Hi-TV maintains the native video format (e.g., Tektronix Profile or Panasonic's DVCPro) throughout the transmission, without returning to baseband video at any point in the transmission process. With the use of a special Pre-Compressed/DVB Input board, Hi-TV also supports single or multiple pre-compressed streams of ATSC A/53 (19.39 Mb/s and 38.78 Mb/s), DVB (SPI and ASI), and SDTI (CSDI and SDDI) network protocol compatible transmissions. With support for IP protocol, Hi-TV users can connect LANs at different locations.
In post production applications, producers can use Hi-TV to send video or batches of files to all the vendors contributing to a project. Multiple streams are made possible by Hi-TV's modular system architecture which consists of a common platform which accommodates 12 boards, with one encoder board required per video stream. The modular design promotes a customizable, grow-as-you-go upgrade path which smaller, budget-conscious companies will find cost-effective.
In addition to facilitating client approvals, large, multi-site video post houses can use Hi-TV to connect all their related buildings to a bi-directional wide area network over which they can move shared video and audio resources. Hi-TV's With its E-1 and T-1 Telephone Circuit Emulation, the same Hi-TV device can even used to connect PBX systems, video conferencing terminals and the like over the wide area network. allows the telephone systems of two different facilities to be connected and operate as one.
Historically there have been a number of problems associated with the video transport services offered through network suppliers – among them: they have generally been single need services, they have not had the ability for dial-up access, and the costs have been high.
Hi-TV has addressed all of these issues, providing a single-box, all-in-one solution for a number of services and a number of channels, giving users the flexibility to stream realtime video or send video data files to anyone over public switched broadband networks. Hi-TV is designed to be a universal, standards-compliant communications tool, that will satisfy the needs of a broad range of video and broadcast professionals.