Re: Svideo does not work - WHY?

Pasi Ojala wrote:

Anyway, now that you mentioned it in another message: I believe
(and someone said this earlier) the original problem with
the LCD really has nothing to do with the interlaced/progressive,
but the 15-16kHz horizontal sync rate that is only supported in
video-capable devices. Even most monitors only support downto 30kHz.
That has been the case for 10 years or more so it really does not
surprise me that a randomly selected LCD does not display the C64
output. (Did the LCD support genuine PAL?)

The OP didn't say whether he lived in a PAL or NTSC area, but he did mention that he tried to connect his C64 to the *s-video* connector of his LCD screen, and that he lost vertical sync. The s-video connector suggests that his LCD screen does support the 15-16kHz horizontal sync rate (if it didn't why would it have a s-video connector?). However I have noticed myself that LCD screens that can handle PAL/NTSC signals (like mine) sometimes struggle with the video signal that the C64/C128 outputs. On my LCD monitor (with composite and s-video inputs) sometimes doesn't even recognize the video signal of my C= equipment at all.

The analog interlaced video signal is such that the circuits of an good-old analog CRT based TV doesn't have to anything really special to properly display an interlaced picture; the signal itself takes care of the interlacing - the TV just has to follow the sync pulses. As long as the sync pulses are in range of what the TV can handle it will display a stable picture, interlaced or not.

However on a LCD panel the video signal needs to processed and digitized, and the circuits have to know whether the pixels should be put on odd or even pixel rows. Consequently the circuits of a LCD panel need to be aware of interlacing. My guess is that some LCD panels get confused when fed a non-interlaced signal.
.

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