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Captioning Specifications

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Published Specifications

This is by no means intended to be a technical library of every specification that relates to captioning.  We'll leave that task to a few selfless souls (W3C and Jose Ramirez are gratefully saluted as examples) and a gaggle of better financed lobbying/advocacy groups (WGBH for example) or industry trade organizations (EIA for example).

But there are a few that are especially pertinent to AutoCaption users:

Timed Text

AutoCaption generates Timed Text (TT) files to be used as part of a SMIL media delivery system.

The W3C has a working group that is honing and distributing this useful standard for causing text to appear periodically in a web browser.

The Closed Caption Specification

For years this specification was kept well hidden.  A few captioning institutions and an electronics company assumed the praiseworthy task of making captioning available in the United States. 

This small group closely guarded and protected the developing specifications during the ensuing years of hard work and millions of dollars in government funding.

Finally the Federal Communications Commission (FCC) published these specifications for all to benefit from.  Another elegant rendition of this information is posted by the folks at Atlas Compliance & Engineering.

Subtitling File Specifications

There are a mind boggling array of file formats for captioning (see list).  AutoCaption™ will generate the popular "STL" text or image formats suitable for Apple's® DVD Studio Pro.™  Nearly all DVD authoring systems can use the images.  A number of systems (a few Sonic® systems, for example) can use the image format STL file without modification.

Modifying a STL captioning file isn't hard.  The basic syntax of all captioning file formats boils down to a lengthy list of time code "in" points, time code "out" points and the name of a file with the caption image.  Fortunately, AutoCaption already did the hard work when making the popular STL file.  It generated all those caption image files and made the necessary index with timing entries.

This means that an ordinary word processor can edit a STL format file into just about any other DVD subtitling format you might encounter.  You'll need to add a few lines to describe the video to be captioned, perhaps perform a few search/replace operations to change column delimiters, and rename the result appropriately.

It's impossible for us to keep up with all the permutations and formats the industry has embellished this repetitious, but simple, information into.  If someone tells you that their's is the "industry standard  file format Click here for a mind boggling list of just the formats we've heard of over the last few years -- and then ask if their file format is openly documented and available to all.

If an AutoCaption user supplies a clear published specification for a particular captioning file format and gives us a working example, Image Logic® is able to make AutoCaption generate that format.  Typically quickly and at no additional charge.


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