I have a customer defining some equipment which outputs analogue video. They have said it would be to NTSC RS-170A standard Y C (on a S-Video, Mini Din connector), however I'm not sure if they really mean RS-343A.

The difference being RS-170 is 1V blank to white, and RS-343A being 0.714V blank to white which I always thought was the common video levels. Sync is -0.3V in both cases.

Has anyone got any idea what the standard video levels would be. I assume they would be the same for Y C / S-Video as for composite.

I have tested a cheap COTS video capture device and this only accepts 0.7V, further making me think my customer really means RS-343A. Before I question it with them I'd like to get a feel for what you guys think. I don't believe they would want to output video levels not commonly commercially supoorted.

  • \$\begingroup\$ RS170A (NTSC) is the standard for television in the US. I don't know why you would think it's not supported. RS343 is a high res standard used on non-broadcast cameras. It depends on what they want to do with the video signal, but if they want 170, give them 170. If you want to make sure, just email them to confirm what they want. \$\endgroup\$
    – I. Wolfe
    Jan 27, 2015 at 15:32
  • \$\begingroup\$ Whats confusing here is I thought all analogue video, regardless of NTSC or PAL is 0.7V for peak white. A web search seems to confirm this, plus when taking a 1V peak white analogue video signal into a video capture card the picture is too bright where as when its set to 0.7V the picture is correct, confirming my suspicions that 1V peak white isn't really a standard that's used...regardless of what the RS170A spec says. \$\endgroup\$ Jan 27, 2015 at 16:31
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    \$\begingroup\$ When I worked in TV, a standard video signal was 1 volt peak-to-peak (sync tip to peak white), with the video portion 0.7 volts, and sync 0.3 volts. I don't recall if sync tip was normally 0 volts or -0.3 volts. (In more ancient times, it was 1.4 volts p-p). \$\endgroup\$ Jan 27, 2015 at 16:50
  • \$\begingroup\$ Yeah that first sentence of mine is incorrect, broadcast has switched from 170A (I guess 2008 is considered "ancient" now). 170A is still used though, and the answer to your question is still to ask the customer. They might want 170A, but if you're concerned just ask them for clarification. I doubt they'll mind \$\endgroup\$
    – I. Wolfe
    Jan 27, 2015 at 16:55

1 Answer 1


I found a good explanation of the confusion with 1V peak or 0.7V peak here:


It seems almost always (as others have alluded to as comments in my above question), 0.7V is standard for peak white, with -0.3V for sync.


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