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A variety of services that help to make television, movies and more accessible for all.


Captioning FAQ

The Caption Production Process
The caption production process is determined by the program: whether it is prerecorded (offline) or live (real time).

Captioning for Pre-Produced Programs
Televised movies, drama series, situation comedies, music videos, and documentaries are produced and recorded onto videotape in advance of the broadcast and can be captioned offline. Trained caption writers, using special captioning software, transcribe the audio portion of a program into a computer, inserting codes that determine when and where each caption will appear on the TV screen. Captions are timed and placed strategically to match shot changes and lip movements, to identify sound effects, (i.e., doorbell, dog barking, thunder, etc.) and to avoid covering important visual information.

The data is then recorded, or encoded, onto a copy of the master videotape, called the closed-captioned master, which should be used for all subsequent broadcast, duplication, or distribution. (For more detailed information on the encoding process, please see MAG Guide, Vol. 5.) A decoder attached to or built into a television receiver can render the captions visible. Offline captioning is a time-consuming process. Depending on the complexity of the program, it usually takes an experienced captioner 15-20 hours to caption a one-hour program.

Because captions are produced ahead of air, offline captions should be 100 percent accurate. Occasionally programs are not finalized until very close to the airtime, and there is not enough time to incorporate last-minute changes into the captions. It is relatively rare, but it does happen. The Media Access Group at WGBH works closely with its production contacts to make sure as much of the final dialogue, sound effects, and music is incorporated into the captions as possible.

Captioning for Live Programs
Live or real-time captions are used to make live or fast turn-around programs accessible. Unlike offline captions created for prerecorded programs, captions created for live broadcast are not timed or positioned and rarely convey information other than the spoken dialogue. The data is encoded into the broadcast signal continuously as the program airs.

Live captions can be used in other situations to assist in effective communication. Some of these situations include meetings, classes, lectures, and court proceedings.

There are four methods for captioning live programming: stenographic systems, manual live display, electronic newsroom systems, and a "hybrid" system that combines stenographic systems and manual live display.

Stenographic Captioning
Most live-captioned programs use real-time technology. A "stenocaptioner" (a specially trained court reporter) watches and listens to the program as it airs and types every word as it is spoken. The stenocaptioner uses a special stenographic keyboard to type as many as 250 words per minute. A computer translates the "steno" into English text formatted as captions. The caption data is then sent to an encoder and inserted into line 21 of the video signal. This is the only method available to caption a live, unscripted program.

Manual Live Display
Manual live caption display involves entering the text before the broadcast and displaying it live at the time of air. Many stenographic captioning systems offer a live display feature for sending pre-scripted material as captions. Computer software products also are available for creating live-display captions. Text for live display is often obtained by downloading it ahead of time or transcribing the audio of prerecorded segments.

Electronic Newsroom
Electronic newsroom captioning is a common method local stations use to make their news broadcasts accessible. In an electronic newsroom, all available script is typed into a network of computers. During the broadcast, the script is displayed on prompter monitors for the on-air talent to read on camera. If the electronic newsroom is equipped with special equipment and software, these scripts can be broadcast as captions.

Hybrid System
The hybrid system is a comprehensive form of captioning that involves a combination of manual live display and stenographic captioning techniques. Pre-scripted segments are entered into a computer before broadcast. A stenocaptioner captions the unscripted segments during airtime. A switching system routes caption text to the encoder from either the live-display computer or the stenocaptioner's computer.

The following chart briefly outlines the advantages and disadvantages of these systems:

Stenographic System
Advantages
  • Provides most complete captioning
  • Only way to caption unscripted segments
Disadvantages
  • Requires specialized personnel
  • Costs of personnel and equipment are high
  • Up to three-second lag time between audio and captions
  • Phonetic errors

Manual Live Display
Advantages
  • Simple and inexpensive to install
  • Highly accurate captions can be created (for scripted material only)
  • Captions can be synchronized with program audio
Disadvantages
  • Incomplete coverage; will not include live interviews or other ad-libbed speech

Electronic Newsroom
Advantages
  • Minimal additional effort required if teleprompter script is already being created
Disadvantages
  • May contain cues and timing information that are not actually spoken
  • Spelling and punctuation also may be optimized for the on-air talent's prompter, rather than for captioning
  • Incomplete coverage; will not include live interviews or other ad-libbed speech

Hybrid System
Advantages
  • Takes advantage of the best features of stenographic captioning systems
Disadvantages
  • Requires specialized personnel
  • Costs of personnel and manual live-display equipment are high
  • Up to three-second lag time between audio and captions
  • Phonetic errors


















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