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Old 20th Jan 2019, 1:16 pm   #10
mhennessy
Dekatron
 
Join Date: Jul 2007
Location: Evesham, Worcestershire, UK.
Posts: 4,238
Default Re: RGB signals from a VCR

Quote:
Originally Posted by emeritus View Post
Just checked the manuals of my VCRs.

The following have RGB in/out

SVHS VCRs:
JVC HR-6855EK, HR-6856EK, HR-6857EK
Panasonic NV-HS950B


Panasonic DV recorder with VHS deck: DMR-EZ48VEB.
Hi,

Have been searching for manuals for each of these - all good fun, but I've exceeded my daily limit on Elektotanya for today!

The JVC machines are simple loop-through only. RGB is not generated or received by the machine. The only wrinkle being red, because of the later revision of the Scart standard that allowed it to carry S-video, where Y is carried on the composite connection, and C is carried on the R path (pin 15).

The Panasonic HS950 machine is also a simple loop-through - it has the same notice that I quoted earlier in post #6. Like many Panasonic S-VHS machines, it has a switch on the rear panel to select whether Scart 1 works in S-video or normal mode.

Of course, the DV machine is a different beast, and it makes sense to use RGB connections (or YPbPr professionally) as DV supports much better picture quality than VHS. Without a manual, I can't say for sure what goes on with the VHS deck - it's possible that they do similar things to the Philips to extract best quality from non-composite sources, and given the progress in technology since the Philips, it's a lot easier/cheaper to do. I presume also that this machine will take the pictures from VHS and decode them internally to RGB (no significant difference in quality if the tape was recorded from a composite source). Of course, the on-screen graphics will take full advantage of the quality of an RGB connection.

I imagine that combined DVD/VHS machines will have similar things in common. With that in mind, I think I need to limit my search to VHS-only machines. Remember what started this - the premise that an RGB connection from a VHS machine to a TV set gives best pictures - and my counter that RGB would not improve on S-video, so apart from Teletext and pass-through, what would be the benefits?

And from studying the Philips VR-813 manual, I've learnt that there is a potential benefit from taking in RGB pictures and turning them to YC for recording. Upon playback, there is still no benefit from RGB compared to S-video, of course (ignoring the teletext/OSD for a moment). Back when this machine was launched, there were relatively few RGB sources out there, so this benefit must have been rather under-utilised - for that reason I do feel sorry for the designers of such a heroic machine!

All of my decent VHS and S-VHS machines (e.g. NV-HD100, NV-FS88) predated RGB loop-through, which is a shame as that would have given me more options about how I hooked up stuff. It's good to learn that RGB loop-through did become a popular facility as we went into the DVD and digital TV ages
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