Development of the descriptive video service
Journal of Visual Impairment and Blindness
Year of publication
Television is an important means of obtaining information and sharing in the culture of this society. Because it is primarily a visual medium, blind and visually impaired people have not had full access to it. In 1990, after five years of research and development, a national service became available over the Public Broadcasting Service that makes television accessible to blind and visually impaired viewers. Developed by WGBH-TV in Boston, Descriptive Video Services provides narrated descriptions of the key visual elements of television programs without interfering with their audio dialogue. Because television is both a visual and an aural medium, blind and deaf people were, for many years, shut out of a fully satisfying experience with television. Twenty years ago, the technology of open captioning, or subtitling, was put to use for people who were deaf; 10 years later, it debuted on commercial television as the technology of closed captioning was developed. Today, closed captioning is included in all prime-time programming. Until the mid-1980s, however, no technology had been developed to provide increased television access to visually impaired persons. Before 1990, people who were blind or visually impaired, including many of the growing number of older people, continued to experience frustration or to be dependent on others for understanding television programs. In January 1990, WGBH, the public television station in Boston, launched Descriptive Video Services, (DVS®) a free, national broadcast service that makes television programs accessible to blind and visually impaired persons. DVS® provides narrated descriptions of the key visual elements of a television program, inserted into the program during pauses in the regular dialogue. It uses a third audio channel to broadcast the narrations. This third audio channel, called the Separate Audio Program (SAP) channel, is found on most new stereo television receivers and videocassette recorders (VCRs). An inexpensive stereo television decoder is also available that converts a monaural television set into stereo with SAP. DVS® is currently available on 36 public television stations across the country and the number is steadily increasing. It is on all episodes of the Public Broadcasting Service's (PBS) American Playhouse, Mystery!, Degrassi High, and The Wonderworks Family Movie. The process of adding description to a television program involves writing the descriptions for insertion during pauses in the dialogue and then narrating the description "to picture" in a production studio. Description writing is a thoughtful, creative, and time-consuming process accomplished by writers who are trained in this special discipline. A DVS® writer (describer) initially views the videotape as a person might who has limited or no vision. The describer then uses specially designed computer software to map out the pauses in a program and to craft the most expressive and effective description possible. When the description is written, reviewed, and edited, a professional narrator voices the script scene by scene. About 16 to 20 hours are required to write the descriptions for a 1-hour dramatic program. It takes 2 to 3 hours for a narrator to record a 1-hour script.