NTSC versus PAL
in [Repair]
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From: William Sommerwerck on 7 Apr 2010 09:23 > Part of the difficulity in understanding is that perhaps you > don't have experience with early American color televisions... > I certainly remember how in the 60s we had to adjust the tint > control on a regular (show by show) basis, because of lack > of consistancy. Yes -- a lack of consistency. That was not the fault of NTSC, but of the broadcasters. > Anyone who had one of those old, tube (valve) color sets, > with the 21" round color CRT, will remember seeing green > skies, and blue grass while having skin colors set to the > proper shade. Get the sky blue, and the skin turned red, > or blue, or green! I don't think that's correct. The cameras (and/or encoders) would have had to have been very badly set up for that to happen. On a related subject... I remember reading long, long ago that the first RCA color TV had /four/ controls for adjusting the color, which the author described as a "combination lock"! Anyone know anything about this?
From: Sylvia Else on 7 Apr 2010 10:08 On 7/04/2010 10:12 PM, William Sommerwerck wrote: >> I'm left wondering what exactly was the *real* problem that PAL >> was intended to fix. It appears that the NTSC tint control could >> only address a fixed phase offset between the colour burst and >> the subcarrier, with both transmitters and TV sets able to >> maintain that offset sufficiently closely that the hue wouldn't >> vary from left to right of the picture. > > Correct. > > >> Other issues, such as non-linear phase shift would have been >> a problem for NTSC viewers, regardless of the tint control. > > Also correct. > > >> So were NTSC viewers tolerating colour pictures that couldn't >> be set right even with the tint control? Or is there something >> else that I've missed? > > You /have/ missed something, which I explained "long ago and far away". > <grin> OK, I vaguely remember your saying that now. In the UK, colour was only transmitted on a new 625 line service (newish, in the case of BBC2), in parallel for a long time with a monochrome 405 line service (except BBC2), and I'd have thought the new transmission infrastructure could have been built to obviate the non-linear group-delay, given that it existed in the USA. And, as I commented before, the Sony Trinitron sets, which didn't implement PAL, performed acceptably according to my memory. Sylvia.
From: Sylvia Else on 7 Apr 2010 10:13 On 7/04/2010 11:23 PM, William Sommerwerck wrote: >> Part of the difficulity in understanding is that perhaps you >> don't have experience with early American color televisions... >> I certainly remember how in the 60s we had to adjust the tint >> control on a regular (show by show) basis, because of lack >> of consistancy. > > Yes -- a lack of consistency. That was not the fault of NTSC, but of the > broadcasters. I have to wonder what the broadcasters were doing to achieve that. Contriving to get the colour burst phase consistent amongst cameras in a studio (so that the tint stayed the same for a show), but inconsistent with the actual colour subcarrier, would take some doing. Sylvia.
From: William Sommerwerck on 7 Apr 2010 10:18 > In the UK, colour was only transmitted on a new 625-line > service (newish, in the case of BBC2), in parallel for a long > time with a monochrome 405 line service (except BBC2), > and I'd have thought the new transmission infrastructure > could have been built to obviate the non-linear group-delay, > given that it existed in the USA. You're probably correct.
From: William Sommerwerck on 7 Apr 2010 10:21
>> Yes -- a lack of consistency. That was not the fault >> of NTSC, but of the broadcasters. > I have to wonder what the broadcasters were doing to achieve > that. Contriving to get the colour burst phase consistent amongst > cameras in a studio (so that the tint stayed the same for a show), > but inconsistent with the actual colour subcarrier, would take > some doing. There is no subcarrier or burst signal in the cameras. They aren't needed at that point, and are added during the encoding process. Setting them up is another matter. The early episodes of "Barney Miller" provide a good example of poor setup, with inconsistent color, and poor convergence. |