Text Size:   A+ A- A   •   Text Only
Find     
Site Image

Tech Facts 6
 
 
Oregon's Deaf and Hard of Hearing Services (ODHHS)-Technical Assistance Center
ODHHS Information and Technical Assistance Series

 
TechFacts: Information About
Captioning for Video Professionals
Volume 6 - "Reduce, Reuse, Recycle, REFORMAT"
(Source: Caption Center)
 
 
 
Closed captions created for a specific program can be used again or "reformatted" for subsequent distribution. Whether programs are changed slightly or edited heavily, the original captions can be reformatted to fit the new version of the program for a fraction of the cost of the original captioning job.
 
Deaf and hard-of-hearing television viewers often ask The Caption Center why a program will air originally with perfect captions and then reappear on other channels or in home video with missing or garbled captions. We also hear from distributors who, unaware that a captioned master already exists, spend significant amounts to needlessly recaption a program. Too often the captions originally created for a program get lost or scrambled along the distribution chain.
 
Almost all programs created these days have an extended life in multiple markets. It is more important than ever for those acquiring programming to request and if necessary reformat the captions, which are as vital to the nation's 24 million deaf and hard-of-hearing viewers as audio is to the general audience.
 
We hope this issue of TechFacts helps distributors take advantage of and preserve captions created for the original airing of a program as they redistribute in other venues. The simple step of reformatting can add value to a program and save hundreds of dollars in captioning costs per episode.
 
 
Editing Video vs. Editing Captions
 
Captions are anchored to a program's SMPTE timecode, and any edits or changes in the program will require separate edits and changes to the caption data.
 
When a program is captioned, the transmission of each caption occurs during a one- or two-second period prior to its appearance. In other words, the packet of instructions sent to the caption decoder-where the caption will be placed, how long it will stay there and what it says-is sent to the decoder before it displays anything. Editing a captioned master can interrupt or destroy parts of these packets, causing garbled and/or missing captions.
 
The same thing can happen when a program is time compressed. The compression equipment removes occasional frames of the video, along with any caption data they may contain, resulting in garbled and/or missing captions.
 
 
Obtaining captioned Masters
 
Most often the only captioned version of a program is the "air master". The archive or library master rarely is captioned. When acquiring a program that has aired or will air before you receive it, we suggest you check with the original producer, rights owner or distributor to ensure you'll have access to the captioned master.
 
If you receive caption files on disk from a broadcaster or distributor, make certain you understand what you're getting. Some caption file formats are readable and can be edited with captioning software. However, many times the broadcaster or distributor receives an "encodable" file from the caption provider. This type of file has strings of computer codes (binary data) mixed in with the captions which work with specific software during the encoding process. Captions are thus timecode-stamped for the original version of the program and will not work correctly with versions which have been edited or time compressed.
 
Most programs that appear on the broadcast networks, and many that debut on cable networks, are captioned. If you are uncertain as to whether a program has been captioned, please contact us. We will do our best to help you find the captions created for your program. The original caption provider should have archived files for your program and can edit them to match your version. You can also ask for an ASCII file of the captions which can be used by most caption providers to reformat the data.
 
Reformatting: A two-step process
  1. A videocassette of the new version is compared with the existing caption file. Adjustments are made in the captions to accommodate the addition or removal of commercial blacks, new material, edits or any other changes.
  2. The reformatted caption data are encoded on line 21 of the vertical blanking interval (VBI) of the new version. Many post and duplication facilities have the equipment necessary to encode captions. Check with us for a list of encoding facilities in your area.
 
 
PAL Closed Captions
 
Different types of captioning are used for broadcast and home video in the PAL universe. Captions similar to our NTSC captions are used in PAL home video, while teletext is used for broadcast. We can reformat your NTSC captions for PAL home video, and we can direct you to the teletext vendor who supplies your foreign licenser for your teletext needs.
 
If a program originally aired in the U.K., Australia or New Zealand, teletext captions may have been created. While it is technically possible to convert and reformat teletext captions into a usable form for NTSC countries, keep in mind that there are vast differences in style and conventions between captioning created in North America and that done elsewhere. While U.S. and Canadian captions are for the most part verbatim, captions created in the U.K. are heavily edited and may not fully serve the American audience. Please contact us for more details.
 
The Caption Center
125 Western Avenue
Boston, MA 02134
617 492-9225
caption@wgbh.org