Re: Difference in luma-chroma delay of C64/C128 compared to standard S-video

From: silverdr_at_wfmh.org.pl
Date: Mon, 4 Sep 2017 18:29:57 +0200
Message-Id: <338AD812-F3FF-4A4E-9A60-1672607EFB52@wfmh.org.pl>
> On 2017-09-04, at 12:13, smf <smf@null.net> wrote:
> 
>> So - as mentioned several times - do I, but I still just tested the signal from a Fluke 54200 using both the Y/C and CVBS outputs. Result: there are no easily measurable differences between the two types of signal. Chroma and luma changes very precisely, seemingly within less than 10ns. Can't really measure it better using the scope only. It's even harder with composite but when placed one over another than the difference between the two is about 11ns. But this only tells that the generator's outputs are 11ns apart, which seems understandable - composite is about 11ns late. 
> 
> The 5 pin c64 didn't have separate chrominance output, it only had luminance and composite. For those you want a 1701 monitor
> 
> The 8 pin c64 added chrominance and +5v. For those you want a 1702 monitor
> 
> https://gona.mactar.hu/Commodore/monitor/Commodore_monitors_by_model_number.html
> 
> I would expect composite to be delayed compared to luminance, because it's gone through more processing. Putting the delay in the c64 would not be cost effective as commodore sold many times more c64s than monitors. There is a monitor specifically for 5 pin c64's, I would hope it takes it into account.
> 
> On the 8 pin c64 then I would hope the luminance and chrominance is in sync, however that doesn't stop the user from trying to use a cable from a 5 pin.
> 
> I vaguely remember trying to use Y/C on a c128 with a philips monitor using a commodore cable and having all sorts of colour bleeding problems. I was probably trying to use the wrong type of cable, I need to dig it out to see whether I figured it out.

I am not sure if we talk the same subject now. What I am trying to say is that there is no perceptible/measurable difference in Y/C timing between the separate and combined (composite) signals in a reference output. I can do the same with a 64, although - the same as Levente - I expect that whatever the modulator changes with its rather simplistic circuit is still negligible.

-- 
SD! - http://e4aws.silverdr.com/


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