Digital Television (DTV) Captioning
Will DTV (a.k.a. HDTV or ATV) have captions?
Does DTV captioning still have XDS data?
Are there any DTV caption encoders available?
Are there any standards for DTV captioning?
Who's responsible for EIA-708?
Where can I get other technical info about DTV captions?
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Will DTV (a.k.a. HDTV or ATV) have captions?
Our new digital TV standard, known as DTV (digital TV), HDTV (high-definition TV), or ATV (advanced TV), will definitely be able to carry captioning information. The current plan is that DTV signals will be able to carry either the new EIA-708 captioning standard or digital programming, or traditional Line 21 broadcast captioning.
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Does DTV captioning still have XDS data?
DTV captioning under EIA-708 does not use XDS per se. There is another mechanism available in a separate data stream for carrying non-caption data such as program names, channel numbers, network IDs, "V-Chip parental content advisories, and so forth. This stream uses the Program and System Information Protocol (PSIP), which is defined by the ATSC A/65 standard.
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Are there any DTV caption encoders available?
Yes. Lucent Digital Video, Ultech Corporation, and EEG Enterprises have all announced caption servers for DTV. Evertz Microsystems announced theirs (the Model 8075) in April 99, also.
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Are there any standards for DTV (a.k.a. HDTV or ATV) captioning?
Yes. The EIA-708 specification provides for dramatically improved captioning. These are a few of the improvements:
An enhanced character set with more accented letters and non-English letters, and more special symbols.
Viewer-adjustable text size, allowing individuals to adjust their TVs to display small, normal, or large captions.
More text and background colors, including translucent (see-through) backgrounds to optionally replace the big black block.
More text styles, including edged or drop-shadowed text rather than the letters on a solid background
More text fonts, including monospaced and proportional spaced, serif and sans-serif, and some playful cursive fonts.
Higher bandwidth, to allow more data per minute of video.
To get a copy of EIA-708, see "Where do I get the American standards documents?"
For more information about digital captioning and EIA-708, see:
Closed Captioning in a Digital Age
Article from Newswaves, Feb 1998
DTV: Closed Captioning in a Digital Age
Article from the Journal of Court Reporting, Jun 1998
Advantages & Pitfalls of Captioning for Advanced Television
Paper presented at the ICCE conference, Jun 1998
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Who's responsible for EIA-708?
EIA-708 is produced and maintained by CEMA's EIA 4.3 (Television Data SubSystems) subcommittee, Working Group 1, which is chaired by your humble FAQ author. For more information, you can visit the EIA's Web site.
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Source :
CapFAQ: Digital television (DTV) captioning