![]() ![]() ![]() Line 21 itself is not viewable on television or videos, but the hidden data is decoded to make captions appear overlayed on a video stream. ![]() This is a transmission data stream that carries closed captions as well as V-Chip data (which provides the small TV rating you see in the top corner of the screen based on violence, language, and more.) TransmissionĦ08 closed captions are transmitted via Line 21 captioning data. AppearanceĦ08 captions are most recognizable for their stereotypical closed caption appearance: white text over a black box.Ħ08 closed captions usually have the classic appearance as depicted in this example. However, 608 captions do not support any of the appearance or customization options offered by 708 captions. 608 captions are compatible with digital television via picture user data, which was meant to make the transition from analog easier. What are 608 Closed Captions?Ħ08 closed captions (also known as CEA-608, EIA-608, or Line 21 captions) were the standard for analog television. And while this support was intended for transitional purposes, 608 closed captions continue to be widely used in digital televisions today. In an effort to make the transition from 608 to 708 closed captioning smoother, digital television maintained the ability to support 608 captions. At the time, it was expected that 608 captions would transition to 708 captions, so 708 closed captions subsequently became the preferable standard by the FCC for all digital television. In 2009, the DTV Delay Act was passed in the United States, officially replacing analog television with digital television. But if 608 is “old” and 708 is “new”, why are we talking about both? Wouldn’t that mean everyone should be using 708 closed captions by this point? Not necessarily. These may also be referred to as EIA-608 and EIA-708, Line 21, CEA-708, or simply just 608 and 708 closed captions.Ħ08 closed captions were the old captioning standard for analog television, while 708 closed captions are the new captioning standard for modern digital television. This has resulted in two main standards for encryption and decryption of closed captioning data based on Federal Communications Commission (FCC) regulations: CEA-608 and CTA-708. Over the years, decoding has evolved alongside television as technology has shifted from analog to digital. I wish I'd made more, but it was extremely time-consuming - though a good way of passing the time as a bored teenager.When closed captions appear on your television screen, a decoder inside the TV translates raw data from a broadcast location and displays it as text that is understandable to the human eye. I still have them, and occasionally dig the disc out for a bit of nostalgia. Getting the graphics done was sometimes tricky, but it was a good way to learn new ways to do things with the limited teletext graphics characters. In years gone by, I remember manually creating copies of teletext pages character by character using a MODE7 editor that I wrote. It just depends on what you want to achieve. With a bit of experimentation, the results from that can actually be quite good. Otherwise, you might as well just photograph the screen of the TV. It would be time-consuming, but the results would look good. Saved images can be transferred via a serial cable to a PC and displayed on a BBC emulator, then captured as a screengrab in Windows. But then, I have those here, so I guess I would say that. I'd say that if you have a good video signal that gives reliable results on a teletext TV set, then the BBC Micro plus teletext adaptor is a good way to go. Never tried it on Betamax, but V2000 was slightly better than regular VHS, for what that's worth Never managed it with any hint of reliability in any standard VHS machine - just not enough video bandwidth. Tapes had to be played back in the same machine for best results (I ended up with 2 or 3 of these machines eventually). Recording teletext was possible on my Panasonic FS-88 S-VHS machine, but it relied on the correct setting of the picture sharpness control to get a reliably recoverable signal. I think we only got 2 or 3 years of use from it before giving up on it. I remember that it was an absolute pig to drive - the user interface was a real horror, so my parents just used it as a basic VCR - and it was very unreliable. It could also be used to bring teletext to non-text TV sets, although the picture was PAL, so nowhere near as nice to look at. Reading about the Philips machine mentioned in #15 reminded me that we had a similar Grundig VCR that had a teletext decoder built in, and could burn subtitles on to recordings.
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