HD/DTV and the Closed Captioning Food Chain

More than 20 million people in North America are either hard of hearing or clinically deaf. Closed Captioning television techniques provide these viewers, with the ability to appreciate the audio speech as well as the video content of the programs being offered. Closed Captioning is also useful in noisy environments, subtitling of foreign languages and for educational material In the NTSC television system, captions are encoded onto line 21 of the Vertical Blanking Interval (VBI). This data may be decoded by the NTSC television set and displayed as subtitles on the screen. The advent of DTV brings enhancements to captioning capabilities and new challenges for the television engineer. It becomes necessary to encode the DTV EIA-708 compliant closed captioning data into the DTV bitstream, at the same time as retaining the NTSC captions required by EIA-608 compliant receivers.

Published

1999-11

Content type

Original Research

DOI

10.5594/M00315

ISBN

978-1-61482-931-7