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This answer reports that in order not to lose quality when digitizing VHS one should use an S-Video cable.

My VCR is a Sharp VC-M401SM and does not have any S-Video output nor a composite output. Instead it has a scart video/audio line.

Question: If I use an adaptor like the following together with an S-Video cable can I obtain a better quality than using the same adapter with a composite cable? Why? Does the answer depend on the tape quality (VHS or S-VHS)?

Scart adapter

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The answer is probably no, unless the SCART socket on your VCR is labeled specifically as "S-VIDEO". The fact that SCART connector has S-Video pins does not guarantee that your VCR provides S-Video signal to these pins. A low-end model will simply transmit a composite signal over the luminance S-Video pin and nothing over the chrominance pin.

Even my DVD player having both S-Video and SCART sockets doesn't provide S-Video signal over SCART. Only component RGB.

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Yes, using the S-Video output of the SCART breakout will give you better quality than if you use the composite output of the same breakout. (You can get even better quality if you use a different SCART breakout that has RGB outputs.)

NTSC and PAL composite signals sacrifice the amount of data about the brightness and color of the scene for the sake of squishing it all together on one easy to use wire. S-Video separates the black and white (luminance) from the color (chrominance) signals, removing some blurring introduced in a composite signal. Using RGB outputs further improves quality by eliminating the bandwidth limitations of combining the three color signals into one.

The improvements will be more noticeable when you are using an S-VHS source because S-VHS has a higher luminance bandwidth than VHS. But you will still have some possibly subtle improvements with VHS, too. The way a VHS tape stores the signal is slightly different (color-under) than NTSC or PAL, so there is some extra loss converting for output to composite compared to converting to S-Video.

(Video Engineering is a solid, highly technical reference for older media technology.)

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  • You said that using a SCART breakout with RGB outputs gives you an even better output quality. With a brief research on the internet I wasn't able to find any video grabber for digitizing VHSs with RGB inputs. All of them seem to have only the composite input and the S-Video input. Why?
    – simonet
    Apr 13, 2020 at 9:57
  • Consumer grade tape equipment doesn't have RGB output. S-VHS is Y/C encoded, so to get a RGB signal you'd have to decode it, which is normally done by the screen. An S-Video output will give you the best quality you could hope for from S-VHS. There might be some advantage for VHS because you won't get any electrical interference from the cable, but most S-VHS players I've used only output a composite signal if you put in a standard VHS tape.
    – stib
    Apr 13, 2020 at 12:05
  • I think that RGB digitisers don't exist because the only tape machines that produce RGB signals were high-end specialised post production machines. Or are you talking about component (Y-pR-pB) when you say RGB?
    – stib
    Apr 13, 2020 at 12:08
  • @stib since I'm in the US, I really haven't encountered SCART in practice, so I can only go off the documentation, which shows RGB pins. The wikipedia article mentions some manufacturers using those pins for HD color difference signals. And while I was speaking hypothetically about component being higher quality than S-Video, I agree that it is highly unlikely to find something capable of handling it.
    – Michael Liebman
    Apr 13, 2020 at 22:52
  • Yeah, I think the RGB pins are for digital equipment like set-top boxes and so on. I think they also get used for the S-video and component signal too, but I'm from Australia so my working knowledge of scart is similarly limited. I think if you search for 'scart component converter' you'll get better results — here's the first page from my duckduckgo search, they have several: selby.com.au/cables/scart-cables/to-component.html You'd need something like the BlackMagic Intensity to digitise it, once you go compnent the price increases a bit.
    – stib
    Apr 14, 2020 at 2:18

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