CLOSED CAPTIONING WITH THE LINE 21 SYSTEM
`
`Sharon Earley
`
`NATIONAL CAPTIONING INSTITUTE, INC.
`
`ABSTRACT
`
`Closed captioning has enabled the hear(cid:173)
`ing impaired to enjoy television more fully
`over the past three years. Although over(cid:173)
`the-air broadcasters have provided the bulk
`of closed-captioned programs, the partici(cid:173)
`pation of the cable industry is both grow(cid:173)
`ing and promising. The Line 21 system, with
`its proven transmission and reception
`strengths, is an ideally suited caption
`delivery system for cablecasters. The Line
`21 signal passes intact over satellite and
`cable. It can be recorded in three-quarter
`and half-inch formats, and no special ac(cid:173)
`commodations are required to retransmit it.
`Decoding devices, specifically designed for
`cable, are currently available, as is a
`system which enables a local operator to
`caption its own prograrrming in a cost(cid:173)
`effective manner. The National Captioning
`Institute sees the full participation of
`cablecasters in the provision of closed
`captions as an important step in increas(cid:173)
`ing the access of the hearing impaired to
`television programming.
`
`CLOSED-CAPTION SERVICE
`
`For the past three decades, television
`has been a primary medium of communica(cid:173)
`tion for most Americans. It has become our
`major source of information about the world
`and our principal source of entertainment.
`But for many years, television's voice
`remained distorted, muted or totally
`silent for some 16 million Americans with
`impaired hearing. The situation changed
`in March, 1980, when the Public Broad(cid:173)
`casting Service and the ABC and NBC
`television networks began broadcasting 16
`hours of predominantly prime-time program(cid:173)
`ming with closed captions produced by the
`National Captioning Institute, Inc.
`(NCI).
`
`Closed captioning involves represent(cid:173)
`ing the sound track of television programs
`in subtitles which are telecast as data in
`the vertical blanking interval and are
`visible only to those viewers whose sets
`are equipped with special decoding devices.
`While in theory closed captions can be
`provided by any teletext system, only one,
`currently known as the Line 21 system, is
`actually in use and delivering captions
`
`nationally. At present, 300,000 viewers
`across ~he country who use Line 21 Tele(cid:173)
`Captio~decoding devices enjoy over 40
`hours per week of predominantly prime-time
`network programming. More than 200 major
`advertisers caption their commercials and
`support the costs of captioning television
`specials and series.
`
`Although the closed-caption service
`began three years ago primarily as a
`broadcast network service, it has expanded
`into many other delivery systems -(cid:173)
`satellite syndication, videocassette,
`videodisk, local broadcast and cable.
`
`DEVELOPMENTS IN CABLE
`
`The cable industry's first involve(cid:173)
`ment in closed captioning was the delivery
`of closed-captioned network programs to
`subscribers. Since 1982, however, cable
`support and involvement in the closed(cid:173)
`caption service has been active and
`growing rapidly.
`
`In early 1982 Showtime became the
`first subscription service to offer its
`own closed-captioned programming -- the
`BIZARRE series. Shortly thereafter Show(cid:173)
`time added selected movies to its closed(cid:173)
`captioned fare. In mid 1982 Colormax Elec(cid:173)
`tronic Corporation began production of two
`closed-caption decoding devices designed
`specifically for the cable audience -- a
`combination converter/Line 21 decoder, and
`a Line 21 decoder module that attaches to
`a cable converter. Such units and the
`standard Sears (Sanyo) TeleCaption decoder
`are being acquired by operators such as
`Tampa Cable Television and American Cable
`Systems, whose specific commitments to
`provide closed-caption decoders were made
`in their franchise bids.
`
`Cable subscribers can now obtaln news
`and features of special interest to the
`hearing impaired via the KEYFAX National
`Teletext Magazine, a service provided co(cid:173)
`operatively by NCI and KEYCOM Electronics
`Publishing. Most recently, Tribune Cable
`Communications, lnc., has agreed to pro(cid:173)
`vide funds to closed caption one movie
`every month for hearing-impaired sub(cid:173)
`scribers. The first movie captioned under
`
`180
`
`1
`
`SAMSUNG 1030
`
`

`
`this arrangement is POLTERGEIST, to appear
`on Showtime in June, 1983. Other MSO's are
`currently considering similar underwriting
`arrangements to provide closed-caption
`services for the benefit of their hearing(cid:173)
`impaired subscribers.
`
`While such activities generate
`enormous good will and demonstrate the
`cable industry's commitment to serve all
`facets of its market, they also make good
`business sense. NCI research indicates
`that while currently only 38% of all
`decoder households subscribe to cable
`television, 82% would subscribe to basic
`cable services if closed-captioned cable
`services were available. Under those
`circumstances, 68% would subscribe to
`pay cable compared to the 28% who currently
`do so. Further, of those who do not own a
`closed-caption decoder, approximately 78%
`would rent one from a cable company.
`
`CLOSED-CAPTION SYSTEM DEVELOPMENT
`
`The Line 21 system was designed
`specifically to provide closed captions to
`the hearing impaired. For this reason,
`fundamental to its specifications was
`that it require little investment in
`effort and hardware by the telecaster,
`that it be sufficiently rugged to pass un(cid:173)
`modified through all television media, and
`that it be inexpensive for the consumer to
`access.
`
`Development of the Line 21 closed(cid:173)
`captioning system was conducted by the PES
`Engineering Department with funds provided
`by the U.S. Department of Health, Educa(cid:173)
`tion and Welfare (HEW) . This work com(cid:173)
`menced in 1973 and was largely completed in
`1979. The PES task had three major compo(cid:173)
`nents, each of which had to be completed
`successfully before a closed-captioning
`service could be implemented.
`
`The first task was to evaluate the
`technique of closed captioning as a mean(cid:173)
`ingful service for the hearing impaired. To
`measure this, PBS established an experi(cid:173)
`mental closed-captioning capability and
`conducted controlled testing with the
`hearing-impaired community during 1974.
`PBS obtained the cooperation of 12 member
`stations across the country who demon(cid:173)
`strated closed-captioned television pro(cid:173)
`grams to the hearing-impaired viewers and
`had them complete over 1,400 opinion forms.
`Gallaudet College, the world's foremost
`educational institution for the hearing
`impaired, analyzed the completed question(cid:173)
`naires. The major findings were that 90%
`of the audience said they could not have
`understood the TV programs shown to them
`had they not been captioned and 95%
`said they would purchase special equipment
`to receive closed captions.
`
`During this same period and on into
`1975. PBS was studyinq the various techni-
`cal hurdles it faced in developing an
`approach to closed-captioned television.
`By November, 1975, sufficient work had
`been completed for PBS to file a petition
`with the Federal Communications Commission
`(FCC) requesting the allocation of Line 21
`for the introduction of a closed-captioned
`service. In December, 1976, the FCC ap(cid:173)
`proved such an allocation. With the FCC
`approval obtained, PBS began fabrication
`of the caption editing console which en(cid:173)
`ables caption preparation to be completed
`efficiently, secured agreements from manu(cid:173)
`facturers to produce the encoder which
`lays the Line 21 data stream into the
`vertical interval and the first consumer
`decoders -- a integrated 19" color
`television set and the add-on decoder -(cid:173)
`which Sears Roebuck agreed to retail.
`Finally, the question of who would perform
`the actual captioning service was answered
`when the non-profit and private National
`Captioning Institute was incorporated
`in early 1979.
`
`CAPTION CREATION AND ENCODING
`
`NCI creates captions in three differ(cid:173)
`ent ways, depending upon the nature of
`the program to be captioned. A recent ad(cid:173)
`vance in caption creation technology
`known as real-time captioning enables vir(cid:173)
`tually every program type to be closed
`captioned. The three methods employed by
`NCI to caption, and a method available to
`local program suppliers, are described
`below.
`
`Prerecorded Programming. NCI receives
`a time-coded videocassette dub of the pro(cid:173)
`gram master and, if available, a script of
`the program. A caption editor works with
`the program in short sections, and corn(cid:173)
`poses each caption. The editor determines
`the caption content, its location on the
`screen, and the times at which it will
`appear and disappear. All of this data is
`entered onto an 8" floppy disk via the
`caption editing console, which has word
`processing capability to facilitate the
`process. Once all captions for a program
`have been prepared and entered, they are
`played back over video and checked for
`accuracy and quality.
`
`The captions on disk are transferred
`to Line 21, Field 1 of the standard NTSC
`video signal in the encoding process. To
`encode captions a Simple Encoder, com(cid:173)
`prised basically of a microprocessor, a
`time code reader and a floppy disk reader,
`is utilized. Required inputs are SMPTE
`time code and program video from the
`master videotape. The microprocessor syn(cid:173)
`chronizes the serial caption data with the
`time code and requests additional captions
`
`181
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`2
`
`

`
`from the disk reader when the encoder
`memory buffer is near depletion. The cap(cid:173)
`tion data is inserted into Line 21 of the
`video.
`
`TAPE ENCODING
`
`Producer
`
`r-
`ENCODING J
`'
`FACILITY I
`I
`I
`I
`1
`I
`I Master
`I Video-
`1
`Master
`I
`Tape
`tape
`Audio
`L..: ___ __ ___ _ __ _ _J
`
`Prescripted Live Programs. Presiden(cid:173)
`tial addresses and other programs which
`are broadcast live are often accurately
`prescripted. With the cooperation of the
`White House or producer, NCI obtains
`the script in advance of broadcast. With(cid:173)
`out the benefit of video or audio, the
`editor must break the text into captions.
`These captions are entered onto the disk
`without preset display and erase times.
`As the live event occurs, the caption
`editor manually recalls the captions from
`the disk for display in sync with the
`audio.
`
`Due to the nature of these programs,
`encoding must be done "live." The hard(cid:173)
`ware which enables live encoding is a
`Smart Encoder. This device is resident at
`the program origination point and is cap(cid:173)
`able of inserting caption data on Line 21
`of the video being fed through ~t. NCI
`transmits the captions to the Smart En(cid:173)
`coder at 1200 baud rate, asynchronously,
`over standard unconditioned telephone
`lines.
`
`LIVE ENCODING
`
`Advance
`Script
`
`Live
`Pro-
`
`Caption
`Editing
`Console
`
`-----,
`
`NCI
`
`I
`I
`
`TV
`
`Live
`Display
`
`I
`.J
`
`r
`I
`I
`J
`L _TB_A!;i.Sl'-'l!S.§.I.Ql-JJ:A.£IIJU - J
`
`Video
`
`I
`
`Live News and Events. For news and
`other programs, scripts are not available
`to NCI in advance of broadcast. Until last
`year, such programs were uncaptionable. In
`October, 1982, however, NCI began to ern(cid:173)
`ploy its real-time captioning system on a
`daily basis to caption ABC-TV's WORLD NEWS
`TONIGHT. The system has been employed to
`caption space shuttle launches and the
`Academy Awards.
`
`The trick to real-time captioning is
`that captions must not only be transmitted
`live, they must be created instantaneously.
`To accomplish this, NCI has borrowed and
`modified a technology employed by court
`reporters to speed the translation of
`machine shorthand to standard English.
`Stenographic translation is the computer(cid:173)
`ized translation into real words and names
`of a stenotypist's machine shorthand
`"strokes" which are a phonetic representa(cid:173)
`tion of what the stenotypist hears.
`
`NCI uses a stenographic translation
`system developed by Translation Systems,
`Inc., modified by TSI and NCI and known
`as InstaText. The heart of InstaText is
`its dictionary system, which translates
`the stenotypist's strokes into real English.
`The main dictionary is called the "univer(cid:173)
`sal" dictionary. This contains the many
`thousands of words in common usage. The
`universal dictionary is the permanent
`facet of the dictionary system, though up(cid:173)
`dated and revised from time to time. Next
`is the "personal" dictionary peculiar to
`the individual stenotypist which contains
`special abbreviations, used only by him or
`her. The third dictionary to which the
`computer will turn to "look up" a word is
`
`182
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`3
`
`

`
`the "dope sheet," which contains entries
`appropriate to a specific task, such as
`the names and places likely to be mention(cid:173)
`ed in a given newscast.
`
`In making translations, the computer
`checks each of these dictionaries and
`matches the stenographic outline entered
`on the stenotype machine with the
`corresponding English word or words. A
`skilled stenotypist will achieve accurate
`translation on better than 97% of all
`entries.
`
`As translation takes place, the text
`is formatted into captions according to
`parameters which can be set either by the
`stenotypist or by an NCI editor operating
`the main computer keyboard. These para(cid:173)
`meters can be set in real time so that
`each line or word can be treated different(cid:173)
`ly, include line length, indentation,
`upper or upper/lower case, and line justi(cid:173)
`fication for left, right, or center dis(cid:173)
`play and display rate.
`
`The text must be then transmitted to
`a display system. In the case of NCI,
`that system is a Line 21 decoder via the
`Line 21 Smart Encoder as described above.
`
`Local Programming. Although NCI has
`and will continue to caption programs
`for local markets, a very cost-effective
`system is available to local stations and
`cablecasters with which to caption pro(cid:173)
`gramming they produce. This system util(cid:173)
`izes a Beston Llectronic Data-Prompter
`and an EEG Smart Encoder. The Data-Promp(cid:173)
`ter is an electronic word processor which
`has a character-generated output that
`can be fed directly to a standard prompter
`monitor. As the text is being presented
`to the talent, it can also be sent to the
`Line 21 Smart Encoder, enabling closed
`captions to be transmitted simultaneously
`with the program.
`
`KCMO-TV, the CBS affiliate in Kansas
`City, is currently utilizing this system
`to provide closed captions for its local
`newscasts and many cable systems are
`showing ihterest in the system for use
`with their local access programs.
`
`DATA-PROMPTER CAPTIONING
`
`Talent
`
`BEl
`Data-
`
`editing terminals
`
`Remote
`Speed
`Control
`
`LINE 21 TRANSHISSION AND RECORDING
`
`Once Line 21 closed captions are in(cid:173)
`serted into video they require no special
`accommodation by the broadcaster or cable(cid:173)
`caster. All that is required is that video
`facilities be checked to insure that they
`are passing Line 21, Field 1 intact. The
`ease of retransmission is due to the rela(cid:173)
`tively low data rate of the Line 21 signal
`which makes it very rugged.
`
`The Line 21 waveform conforms to the
`standard Television Synchronizing Waveform
`for Color Transmission given in Subpart E,
`Part 73 of the FCC Rules and Regulations.
`The composite data signal contained within
`the active video portion of the line
`period carries a clock run-in (data syn(cid:173)
`chronizing signal), and a start bit,
`followed by 16 data bits. The instanta(cid:173)
`neous data rate is thirty-two times hori(cid:173)
`zontal line scanning frequency (32FH) for
`a nominal value of 0.5 mb/s. After allow(cid:173)
`ance for the duty cycle of the Line 21
`signal, and start bits, an average data
`transmission rate of 480 bits per second
`is obtained which translates into 60
`characters (7 bit ASCll + 1 parity bit)
`per second.
`
`Just as Line 21 closed captions pass
`without difficulty over existing trans(cid:173)
`mission modes -- over-the-air, cable and
`satellite -- they are recordable in all
`existing video formats, including 3/4-inch,
`1/2-inch (Beta and VHS), and video disk.
`When programming is transmitted on a 3/4-
`inch format, however, it is important to
`note that many 3/4-inch cassette machines
`do not have framing (field differentiat(cid:173)
`ing) servo systems and will randomly lock
`in the opposite field from a house refer(cid:173)
`ence sync. This will usually be the ad(cid:173)
`vanced vertical from a time base corrector
`when it is connected to the playback
`machine. As a result, Line 21, Field 1
`information may flip to Field 2 on either
`
`183
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`4
`
`

`
`Line 2 0 or Line 21. '1'he home decoder
`must see caption data on Line 21, Field
`1 in order to decode and display captions.
`(The Sony BVU series, or its equivalent,
`that employs a framing servo does have this
`problem and can be used with a time base
`corrector without exhibiting field rever(cid:173)
`sal providing the program was recorded
`on a machine with a framing servo.)
`
`If a non-framing servo machine is used
`for playback with no time base correction
`and the signal that was recorded is at
`proper IRE levels, then Line 21, Field 1
`information recorded on the tape will re(cid:173)
`main unaltered during playback, allowing
`captions to be decoded and displayed on
`the home receiver.
`
`LINE 21 AND TELETEXT
`
`The FCC decision last month to pre(cid:173)
`serve Line 21 for closed captioning came
`as welcome
`support to hearing-impaired
`consumers who have made an investment
`of over 30 million dollars in home de(cid:173)
`coding equipment to date. The open-market
`approach to teletext standards,including
`the ruling by the Commissioners that cable
`television systems are not bound by the
`must-carry rule insofar as broadcast
`teletext services are concerned,and the
`adoption of incompatible teletext systems
`by broadcasters and cablecasters alike,
`will mean that for the foreseeable future
`the Line 21 system will remain the only
`national delivery system for program-re(cid:173)
`lated captions.
`
`With the advent of teletext in the
`United States, NCI recognizes the practi(cid:173)
`cality of making the Line 21 system
`compatible with the various teletext
`
`systems so that hearing-impaired
`viewers who invest in teletext decoders
`do not also need Line 21 decoders. To(cid:173)
`ward that end NCI·has been cooperating
`with World Standard and NABTS teletext
`equipment manufacturers to develop a
`black box which can transcode Line 21
`captions to either teletext format.
`Such transcoders will enable captions
`to pass as usual on Line 21 and to be
`duplicated and transmitted simultaneously
`in the appropriate teletext format.
`
`In November of 1982 such transcoding
`between Line 21 and World Standard
`-
`teletext was successfully demonstrated
`in Washington, D.C. In March, 1983, a
`transcoder was installed at \'VNET-TV
`in New York with transcoded captions
`transmitted by Manhattan Cable. An
`NABTS transcoder is currently under
`development in Canada and is expected
`to be available this fall.
`
`CONCLUSION
`
`The Line 21 system for closed
`captioning has become widely accepted
`and utilized in the four years since it
`made its debut, and its growth continues
`at an exciting pace. Major support for
`the system is arising from the cable in(cid:173)
`dustry. The creation, transmission
`and reception of closed captions is
`reliable, straightforward and proven.
`For cable operators who wish to provide
`this valuable service to the hearing
`impaired, the Line 21-based system is
`a cost-effective and trouble-free way
`to do so. NCI has every expectation
`that the growth of cable television across
`the nation will lead to increasing access
`to television for the hearing impaired.
`
`184
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`5