Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Posting-Version: version B 2.10.2 9/18/84; site topaz.ARPA Path: utzoo!watmath!clyde!bonnie!akgua!whuxlm!harpo!decvax!genrad!panda!talcott!harvard!seismo!columbia!topaz!Alan%DCT.AC.UK%DUNDEE.AC.UK@ucl-cs.ARPA From: Alan%DCT.AC.UK%DUNDEE.AC.UK@ucl-cs.ARPA Newsgroups: net.sf-lovers Subject: Re: RHPS, Magenta, and UK video tapes Message-ID: <2329@topaz.ARPA> Date: Thu, 20-Jun-85 09:38:33 EDT Article-I.D.: topaz.2329 Posted: Thu Jun 20 09:38:33 1985 Date-Received: Sun, 23-Jun-85 01:34:32 EDT Sender: daemon@topaz.ARPA Organization: Rutgers Univ., New Brunswick, N.J. Lines: 60 From: Alan Greig > From: callaghan%pseudo.DEC@decwrl.ARPA (Gaylene Callaghan > From: DTN:523-4523) > Subject: RHPS, Magenta, and UK video tapes > BTW, I was under the impression that the UK videos cannot be played > on US machines. That means you would need to buy a UK machine to > copy the UK video to US tape. If someone in UK has a US machine, I > would be glad to send them a tape to get a copy. Ok, here's the facts on TV standards (as far as I understand them anyway) North America and some other parts of the world use the NTSC colour system (sorry color) at a 30 Hertz field rate. Europe and many other parts of the world use PAL or SECAM colour at 25 Hertz. The problem with trying to show a PAL tape in an NTSC environment on single standard equipment is then that the VCR sees all the timing signals at the wrong time and so can't decode a picture and that the colour information is encoded in a different form. The first of these problems can be eliminated by just changing the timebase crystal and many modern VCR's can now decode at either field rate. This gives a monochrome picture at 25Hz. which can be displayed by NTSC televisions because the line and frame oscillators have a wide enough lock range to synchronize with the slightly slower timing. The *big* problem comes with displaying this in colour on an NTSC system. Firstly there is no colour signal coming from the VCR and even if there was, the tv couldn't do anything with it. To solve this, the VCR must be capable of decoding PAL information. Again there does exist multi standard equipment which can do this. Next there must be a tv set which can accept PAL. In Europe at least, it is fairly common for tv sets to be able to do decode PAL/SECAM and NTSC automatically. I suspect the same will be true in the US as the Japanese design tv sets for all world markets and it keeps there costs down if they can keep the designs as similar as possible. All of the above might sound complicated but is actually quite easy to achieve mainly because multi standard equipment is becoming a lot more common. Converting a tape is as far as I know very difficult. How do you make 25 frames into 30 without using lots of digital storage ? Oh well in these days of these micro computer thingies, I suppose its much cheaper than in the old days. Still the somewhat jerky movements that result when live NTSC events are broadcast over here in PAL show that even with expensive equipment that the BBC and ITV use, the results are not particularly amazing. Meaning ? Well I think people can forget about trying to copy UK PAL tapes onto NTSC tapes without degrading the picture quality quite considerably. Go for some degree of multi-standard. NTSC is a terrible colour system anyway and PAL is much better. But then I suppose thats the price you have to pay for pioneering colour television. Hope this has all been reasonably correct and has some relevance to SF-LOVERS. I'm sure I'll be told if its isn't ! Alan -------