2009

Handling Closed Captioning
Closed captioning is a subtitling system designed to make television more accessible to
the hearing-impaired. Unlike movie subtitles, which are intended to translate dialogue
for people who can hear the rest of the soundtrack, closed captions need to convey all
important sound effects, music cues, nonverbal expressions, and dialogue that occur as
a program plays.
The FCC mandates that distributors of programming for residential use must provide a
minimum number of hours of closed-captioned programming per calendar quarter. This
rule affects terrestrial and satellite broadcasters as well as cable operators. Although there
are exceptions, the result is that many broadcasters insist on a closed-captioned tape
master as one of their deliverables.
Closed captioning is encoded in a variety of ways, depending on the video format.
• SD analog and digital NTSC broadcast, tape, and DVDs: Closed captioning for SD analog
television is a text-only data stream that’s encoded into line 21 of an NTSC video signal.
This is one of the reasons for the series of blinking dashes and lines that runs along the
edge of a video image when you put a monitor into underscan mode. SD digital video
uses the CEA-608 standard of closed captioning, which can be encoded into an MPEG-2
stream. Because closed captioning is encoded right into the video signal, it can be
included and recorded on videotapes; broadcast over the air, via satellite or cable;
included on DVDs; and even recorded using digital video recorders (DVRs) such as TIVO.
• SD and HD digital television broadcast and tape: Although high definition television
(HDTV) originally supported line 21–style closed captioning, the proliferation of new
HD digital video formats necessitated a new approach. To accommodate HD video
encoded using a variety of methods, the EIA-708 closed captioning standard for ATSC
digital television was developed. This standard has since been superseded by CEA-708,
which covers both SD and HD digital television. In this standard, closed captioning data
is stored in the vertical ancillary (VANC) data of a digital video stream. Final Cut Pro and
Compressor both support the embedding of CEA-608 closed captioning within the
CEA-708 standard.
• European television: Closed captioning in European television is based on teletext, a
text-only information retrieval system for television originally developed in England.
Digital broadcasters in Europe currently use the DVB-T and DVB-S standards for encoding
teletext-style data into digital video streams. Final Cut Studio does not support these
standards.
Closed captioning is actually displayed by the television receiving the video signal, which
means that it can be turned on and off at will. This also means that the font and style of
the closed captioning is dependent on the television. Closed captions are simply plain
text.
101Chapter 6 Mastering