Closed Captioning
see http://www.robson.org/capfaq/ and http://www.fcc.gov/cgb/consumerfacts/closedcaption.html
Closed captioning (CC) is a technology that provides visual text to describe dialogue, background noise, and sound effects on television programming. As of July 1993, all television sets with screens 13 inches or larger sold in the United States must have built-in decoder circuitry that allows viewers to display closed captions on their sets. In 1996, Congress passed a law requiring video program distributors (cable operators, broadcasters, and satellite distributors) to phase in closed captioning of their television programs. Viewers may select to watch closed captions through their remote controls or on-screen displays. The new law does not require captioning of home videos or video games.
Technical Aspects of CC
CC (Closed Captioning) is Transmitted on line 21 of NTSC/525 transmissions, contains subtitling information only. Caption 1 & 2 and text 1 & 2 are stored in line 21 of the first field in each frame. The second field's line 21 can be used for caption 3 & 4 and text 3 & 4. CC supports up to 8 colors and can display regular or italic text.
Confusion on the CC line:
According to Robson's page - Caption 1 & 2 and text 1 & 2 are stored in line 21 of the first field in each frame. Caption 3 & 4 and text 3 & 4 are stored in line 21 of the second field.
I am wondering what line number the second CC line would be, using the full 525 lines for counting. If you count them upwards from 1 to 525 then the first CC line would be line 21 and the next line would be the 21st line in the second field. Since there are 262.5 scan lines per field, then the second field begins scanning at line 263.5 - add 21 to that and "apparently" (and I can't believe anything anymore) the second CC line is line 284.5
One oddity, is that this model has the vertical retrace occuring first - the first 20 lines. Many models I have seen show the vertical retrace
occuring at the end of the field - the last 20 lines. I guess it is not important since it is a continuing series.
Now - is the second CC line actually line 284.5 ? I would not think that the system begins the CC info halfway across a scan line, so they probably use line 284 or line 285 ? Again, I have not seen this detailed so I cannot be sure. Hopefully someone has the answer or maybe a link that explains it while taking into account the fact the the second field begins scanning at line 262.5 (or at least it seems to be a fact, since all the diagrams that I have seen show the second field scanning beginning halfway across the screen).
The FCC CC Regulations
New Programming
All English language programming, which was first shown on
or after January 1, 1998, must be captioned over an eight-year period, by 2006.
The Federal Communications Commission (FCC) has set benchmarks to meet this
deadline. These benchmarks measure the amount of programming that must be
captioned each calendar quarter (every 3 months) and are as follows:
2000: 450 hours of programming per channel per quarter
2002: 900 hours of programming per channel per quarter
2004: 1350 hours of programming per channel per quarter
2006: 100% of all programming, with some exemptions
Pre-Rule Programming
Programming first shown before January 1, 1998, is called
pre-rule programming. Seventy-five percent of this programming must be captioned
by 2008 under the following schedule:
2003: 30% of programming per channel per quarter
2008: 75% of programming per channel per quarter
Spanish Language Programming
Because captioning is fairly new to Spanish language
program providers, the FCC has provided a longer time period for compliance by
these programmers. All new Spanish language programming that was first shown
after January 1, 1998, must be captioned by 2010. The following schedule applies
to Spanish language programming shown after January 1, 1998:
2001: 450 hours of programming per channel per quarter
2004: 900 hours of programming per channel per quarter
2007: 1350 hours of programming per channel per quarter
2010: 100% of all programming, with some exemptions
For programming first shown before January 1, 1998, the following schedule
applies:
2005: 30% of programming per channel per quarter
2012: 75% of programming per channel per quarter
Exemptions
There are some exemptions to the above captioning rules (for both English and Spanish language programming). For example, captioning is not required for:
Programs which are shown between 2 a.m. and 6 a.m. local time;
Locally produced and distributed non-news programming with no repeat value (e.g., parades and school sports);
Commercials that are no more than five minutes long;
Instructional programming that is locally produced by public television stations for use in grades K-12 and post secondary schools (only covers programming narrowly distributed to individual educational institutions);
Programs in languages other than English or Spanish;
Programs shown on new networks for the first four years of the network’s operations;
Public service announcements under 10 minutes, unless they are federally-funded or produced; and
Video programming providers with annual gross revenues under $3 million (although such programmers must pass through video programming that has already been captioned).
In addition, a video programming provider or distributor may ask the FCC for an exemption for specific programming if supplying captions for that programming would result in an undue burden for the provider or distributor.
Real-time vs. Electronic Newsroom Captioning Technique
Real-time captioning typically uses stenographers to convert the entire audio portion of a live program to captions. Electronic newsroom captioning technique (ENCT) creates captions from a news script computer or teleprompter used for live newscasts. Because only material that is scripted can be captioned with this technique, breaking news, sports and weather updates, and live field reports are typically not captioned when ENCT is used. As of January 1, 2000, FCC rules have not permitted the four major national broadcast networks (ABC, CBS, Fox, and NBC), television affiliates of these networks in the top 25 television markets, and national nonbroadcast networks (e.g., cable) serving at least 50% of the total number of households subscribing to video programming services, to count live news programming using ENCT toward their captioning requirements. Rather, these networks and affiliates must provide real-time captioning for live news programming in order for it to count toward meeting the FCC’s captioning schedules. Other programming distributors and providers, however, are permitted to use ENCT for live programming to meet the captioning mandates.