Advanced Television Closed Captioning
(Source: National Center for Accessible Media)
Advanced Television (ATV), also known as Digital Television (DTV) will dramatically change television technology within the coming years. ATV, which incorporates the technologies known as High-Definition Television (HDTV) and Standard Digital Television (SDTV)--is a complete re-design of North America´s television service. It will be completely digital, and will feature a sharper picture, an aspect ratio resembling that of a wide-screen movie, multiple CD-quality audio channels, and ancillary data services. ATV will also make exciting new caption features possible such as multiple caption streams (enabling viewers to choose between different languages or different reading levels), a wider range of character sizes, fonts, and colors, and increased flexibility regarding caption placement. ATV may also allow users to customize the appearance of captions on their television sets.
The ATV Closed Captioning Working Group was created to develop a captioning specification which best serves deaf and hard-of-hearing viewers while also serving the needs of the designers and manufacturers of the coming digital media. The ATVCC Working Group operates under the aegis of and reports regularly to the Television Data Systems Subcommittee of the Electronic Industries Association. It consists of the top three caption service providers (The Caption Center at WGBH, the National Captioning Institute, and Vitac); the major caption hardware and software companies (Avio Systems, EEG Enterprises, Inc., SoftTouch, Inc., and Ultech, Inc.), four major receiver manufacturers (Panasonic, Philips Consumer Electronics, Thomson Consumer Electronics, and Zenith Electronics Corporation), and a leading manufacturer of hardware for Digital TV transport (General Instruments). The Working Group is designing the best specification for the greatest number of people, managing its implementation as a national and international standard, and publishing recommended practices for its use. The goal is to design a closed-captioning system for Advanced Television that will perform according to user and industry needs, will be both forward- and backward-compatible, and will promote the development of a practical and affordable system for ATV closed-captioning workstations, encoders, transcoders, and decoders.
The Working Group´s Activities include the following:
1. Drafted a specification for ATV Captioning
The document entitled "Recommended Practices for Advanced Television Closed Captioning" provides a definition of ATV closed captioning and guidelines for caption service providers and manufacturers of ATVCC decoders and encoders. This specification was accepted as a draft standard (EIA-708) by the Electronic Industries Association in December 1995. In June 1997, the EIA´s Television Data Systems Subcommittee voted to accept it as an official interim industry standard. The document will be submitted later this year to the membership of the EIA who will vote on whether it should become an official industry standard. The balloting process will allow a period for comments and changes.
2. Created a list of minimum features for ATV closed caption decoders
The Working Group has proposed a set of caption display and operational features that ATV set manufacturers could be required to implement. The features are a subset of those described in EIA-708. The criteria for this minimum feature list are viewability and readability. Features which go beyond this standard may be considered optional and to be used at the manufacturers´ discretion for marketing or competitive reasons.
3. Developed software to simulate ATV caption creation and decoding
The Working Group developed an ATVCC simulator to: (1) serve as a reference design for real ATVCC decoders; (2) facilitate the development of caption creation software; (3) enable the ATVCC Working Group to further refine the ATVCC Specification; and (4) allow ATVCC demonstrations without specialized equipment.
The ATVCC Simulator consists of two programs: the ATVCC Simulator and the ATVCC Caption File WorkBench. Both run on computers executing the Microsoft Windows operating systems. The ATVCC Caption File WorkBench is a utility for creating ATVCC caption files, and for generating ATVCC formatted (EIA-708) caption data streams. The ATVCC Simulator is a sample implementation of an ATVCC caption decoder which interprets the caption data stream and formats and displays the captions in accordance with the EIA-708 standard.
4. Conducted market research with consumers
The Working Group conducted two phases of market research to obtain input from current and potential caption users about features that may become possible with ATV. The information obtained through this research will assist receiver manufacturers in determining how to design their products to best serve caption consumers.
5. Conducted caption tests at WHD-TV
The Working Group is working with WHD-TV, the model experimental digital television station at WRC-TV in Washington, DC, to conduct tests of actual Advanced Television closed captioning.
The Working Group has done a laudable job of developing a captioning system that will serve current and future users of captioning. The Working Group has fulfilled its primary goal of creating a specification for ATV closed captioning, played a key role in the design of data transport within the ATV signal, and created a set of recommended captioning features which will strongly influence the design of ATV receivers. The Working Group is coordinating its efforts with experts in the media and technology industry to ensure that the captioning standard is compatible with other forms of media (e.g. CD-ROMs, DVDs, the World Wide Web). Perhaps most importantly, the Working Group has increased awareness and understanding of captioning within the television industry. Although much of the future of ATV is still uncertain, the Working Group has ensured that the interests of caption consumers have been well represented.
Key Working Group activities have been funded by the U.S. Department of Education (PR/Award # H026R30003).
In April 1997, the Working Group hired the WGBH Television Viewing Lab to conduct interviews with caption consumers about potential ATV caption features..
For more information, contact:
CPB/WGBH National Center for Accessible Media
WGBH Educational Foundation
125 Western Avenue
Boston, MA 02134
(617) 492-9258 (voice/TTY)
(617) 782-2155 (fax)