From: Susan Thompson suethomp@ozemail.com.au
To: VIP-L vip-l@softspeak.com.au
Fr
DigitalBroadcasting.com
http://www.digitalbroadcasting.com/content/news/article.asp?DocID={2186A50D-E56A-11D4-A76F-00D0B7694F32}&Bucket=HomeFeaturedArticles
Bringing closed captioning and video descriptive services to the DTV era
1/8/2001
How WGBH s NCAM Division and its DTV Access Project are helping to advocate media access by the disabled.
By Claudia Kienzle, for Digitalbroadcasting.com
Table of contents
Closed Caption Crusaders
FCC, CEA, ATSC among the players
The Challenges of Digital TV
By July 1, 2002, The FCC has ordered that all DTV receivers must include DTV-compliant closed captioning decoder circuitry, and all programming produced for DTV must include closed captioning.
While closed captioning is a widely deployed service in NTSC, it is a work in progress in DTV. The technical standards for DTV transmission of closed captions (on-screen text relaying spoken dialogue to the deaf and hard of hearing); and video description (narration describing what is happening on-screen for the blind or visually impaired) are still being developed.
But The CPB/WGBH National Center for Accessible Media (NCAM), a division of Boston PBS station WGBH, is working to develop technologies that enable access to public mass media including the Internet, DVDs, movies, and especially DTV by millions of Americans with sensory disabilities.
Closed Caption Crusaders
CPB/WGBH s NCAM has taken a leadership role, working with the CEA, ATSC, and manufacturers, to insure that valuable services like closed captioning and video description become viable in the DTV marketplace. When we studied the DTV signal s path from TV studio to home, we found there were many gaps that needed to be filled in order to enable an end-to-end solution for closed captioning and video description, says Gerry Field, Manager of the DTV Access Project at the CPB/WGBH National Center for Accessible Media (NCAM), in Boston, MA.
We've maintained a high profile at industry meetings; and assisted manufacturers in their end to end testing of prototype encoders, decoders, and receivers. There are many complex technical issues that need to be resolved, such as making sure that every encoder and decoder handles caption and description data in a similar fashion. Also, by 2002, all DTV receivers will have to have a minimum set of caption features such as user control over the font size and style of the closed caption display, adds Field.
Consistent with The WGBH Educational Foundation's 30-year long commitment to develop and further broadcast services for people with sensory disabilities, NCAM is working with all parties to insure closed captioning and video description services don t get lost in the shuffle as the industry transitions to DTV. Among the related equipment manufacturers working with NCAM are Mixed Signal Technologies (Ultech), EEG, Evertz, Norpak, Dolby Labs, Panasonic, and Sony.
In June and September 2000, NCAM provided test materials for the CEA and ATSC co-sponsored plug fests, or product demonstrations, to evaluate current DTV encoder and receiver ability to process caption and video description data. NCAM is a member of the CEA R4.3 Working Group 1, which has produced all the enabling standards for captioning and content advisory information via DTV receivers. NCAM also participates in the ATSC Implementation Subcommittee, and serves on the Technical Steering Committee of the DTV Station Project, Inc.
FCC, CEA, ATSC among the players
In July 2000, the FCC incorporated sections of our EIA 708-B DTV closed captioning standard into its rules as part of its standard for display of closed captioning on DTV receivers. We are continuing in our efforts to help manufacturers implement DTV closed captioning. The CEA/MSTV DTV Model Station Project (WHD-TV in Washington, DC) is sponsoring off-air tests to ensure the interoperability of combinations of signals such as analog/digital closed captioning, region rating tables and other content advisory information. We are also preparing sample closed captioning bit streams for manufacturer testing and product development use, says Michael Petricone, Vice President of Technology Policy, Consumer Electronics Association in Washington, DC.
The Advanced Television Systems Committee (ATSC), is focused on the transmission of closed captioning and video description. The ATSC s PSIP (Program and System Information Protocol) is used to announce caption and audio services to DTV receivers. The exact specifications for captions have been set by the CEA, says Mark S. Richer, Executive Director for the ATSC in Washington, DC.
In NTSC, closed captioning is inserted within the Vertical Blanking Interval (VBI) of the signal, while video description is carried in the Secondary Audio Program (SAP channel) feature of stereo television. But neither of these means exist in DTV.
The Challenges of Digital TV
So, the challenge for broadcasters is to create digital signals that maintain current levels of service while implementing the new, advanced features that the ATSC standard will allow. According to Field, back in November 1998, when WCVB-DT, the Boston Hearst-Argyle station ABC affiliate, wanted to put closed captioning on its DTV programming, we helped find an innovative soolution to make that work. We worked with Harris/Lucent and Ultech, two manufacturers whose encoders were in use at WCVB, and devised a closed caption data server that could transcode the captioning in the NTSC signal to the DTV signal. While the NTSC signal was up-converted to ATSC, the EIA-608 caption data was extracted from Line 21 of the VBI and simultaneously transcoded to digital EIA-708 format.
As the transition progresses, more and more programming will be originated in native DTV form, and captions and video descriptions will then be authored in native DTV form, adds Field. For caption and video description agencies and program distributors, solutions must be found to allow authoring formats that can take full advantage of the extended DTV feature sets, while providing cost-effective support of the installed base of NTSC devices throughout the broadcast chain, in-plant, and to the home. For broadcasters, integrated solutions are needed to support closed captioning and video description source material from the point of contribution through network distribution, in-plant routing, and to the encoding, multiplexing, and transmission stages.
NCAM and the DTV Access Project have received funding to support their research and development efforts; participation on industry standards committees; and technical consultation services to broadcasters all designed to promote their use of captions and descriptions in DTV. Among the funding sources are: The Corporation for Public Broadcasting Television Future Fund, The U.S. Department of Education s National Institute on Disability and Rehabilitation Research, and a growing corporate business partner program.
But NCAM's DTV Access Project has a long road ahead in its goal to promote widespread deployment of closed captioning and video description in DTV. One example of the DTV broadcaster's attitude was expressed by Steve Welch, Director of Engineering and Operations for KQED-TV, the PBS affiliate in San Francisco, CA, Closed captioning on our DTV channel (Channel 30) has just not been on our radar screen, since the standards are still being finalized. The recent FCC decisions will help to move this along. We want to provide these services, but we need the hardware and software solutions to support them.
For more information about WGBH's DTV Access Project and NCAM, go the NCAM website at www.wgbh.org/ncam
Claudia Kienzle has been writing for the broadcast industry for over a decade.
She can be reached at ckienzle@optonline.net
--
Mary Watkins
Outreach Manager
Media Access Group at WGBH
(The Caption Center, Descriptive Video Service,
CPB/WGBH National Center for Accessible Media)
mary_watkins@wgbh.org
access.wgbh.org
125 Western Avenue
Boston, MA 02134
617 300-3700 v/fax
617 300-2489 TTY
"WGBH Boston informs, inspires, and entertains millions through public broadcasting, the Web, educational multimedia, and access services for people with disabilities."
Regards Steve,
mailto: pattist@ozemail.com.au
