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Why didn't I see an improvement using s-video?


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9 replies to this topic

#1 of 10 Ted Lee

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Posted December 13 2001 - 03:42 AM

hi all -

i recently bought a new 32" sony tv (32s42?). since it has s-video capability, i ran a s-video cable (rat-shack gold) from my dvd player (sony 560d) to the tv.

i didn't see much improvement. the edges did not seem any sharper and curved edges had the same amount of "jaggedyness". i froze some dvd scenes to try to compare.

i had both composite and s-video hooked up simultaneously. i compared the s-video input, then unplugged it and checked the composite input. everything looked the same.

so, am i missing something? (even though i'm not a believer of hi-end cabling, i'm going to buy some "better" cable and see if that makes any difference.) or is my eye just not sensitive enough?

tia
 

#2 of 10 RoyGBiv

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Posted December 13 2001 - 03:59 AM

Ted:

First, on a 32" TV, the difference may not be startling. I think you should notice a difference, though. But, here is what may have happened. If you had both component and s-video hooked up at the same time, your TV may have preferentially used the component input to display the picture. Then, when you unplugged the s-video nothing happened because you had been watching the component all along. Have you tried it with only the s-video connected?

SMK

#3 of 10 Barrett

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Posted December 13 2001 - 04:04 AM

Ted,

Don't go waste money on a more expensive S-video cable; if you couldn't discern a difference between composite and S with a Radio Shack Gold cable, you won't discern a difference with any S-video cable.

Here are a couple of obvious things you could look for to try and see the difference between composite and S connections. Find a scene where a character is wearing a tweed jacket (lots of fine detail). With the composite connection, you'll probably notice that the jacket will be swimming with funky, shifting "rainbow" (moire) artifacts (you see this all the time on the evening news, for example). With the S-video connection, those rainbows should all but disappear, as they are primarily due to the inability of the comb filter in the TV to perfectly separate the black-and-white (luminance) information from the color (chrominance) information that have been interleaved or "blended together" in the composite video signal. (The S-video connection keeps the luminance and chrominance signals separate and therefore the TV's comb filter is bypassed.) Next, put in an animated (that is, hand-drawn cell animation, like traditional Disney movies) DVD. Look for areas where two large patches of bright color meet up with each other (but not separated by a black line). With the composite video connection, you may see dot crawl or hanging dots (looks like a moving "zipper" pattern) along those color boundaries. With the S-video connection, those dot artifacts will disappear, for the same reason stated above.

If you can't see moire or dot artifacts with these types of images, then you just must have a really good comb filter in your TV. Even then, since you already have a decent S-video cable, use it anyway. Good luck!

#4 of 10 Ted Lee

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Posted December 13 2001 - 04:04 AM

hi steve -

yes, i was able to verify that my tv will always select the s-video signal if both video inputs (s-video & composite) are simultaneously connected. i was running a composite vcr signal to the composite video in. when i plugged in the s-video the tv switched to the dvd signal.

so, when i plugged in the s-video cable, that is the picture i was seeing. when i unplugged it, then i was seeing the composite signal.

in any case, i also did completely unplug the composite and was feeding a s-video only signal to the tv.

still no noticeable improvement in picture quality.
 

#5 of 10 Ted Lee

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Posted December 13 2001 - 04:07 AM

thanks barrett - those are great suggestions. i forgot all about the moire test. i'll give it a shot. i know the scene from austin powers is a good test for that. i'll also pop in some animation and give it a look.
 

#6 of 10 Bob McElfresh

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Posted December 13 2001 - 04:18 AM

Yes, SVideo gives a 20% "better" picture on a 50" TV. Smaller TV's show less improvement, larger show more.

What you are really seeing is a "reduction in imperfections". SVideo does NOT improve the sharpness/resolution/information.

It's really obvious with a DSS receiver that has a on-screen program guide. The text & grid-outline is much more solid, easier to read with SVideo vs composite.

Look for straight-line intersections for dot-crawl. White text on a black background is common in many menu systems. Video game systems are dramatically different with the 2 connections because of the straight lines and lots of solid/contrasting colors.

Or look at the .... I think it's the Snell & Willcox test pattern on Video Essentials or Avia DVD's. It stays still and should "shimmer" with composite, but be more solid/stable with SVideo.

#7 of 10 jeff lam

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Posted December 13 2001 - 04:19 AM

I have the same TV but in the 27" model. I ran composite to the TV with s-vid switched from the receiver. Try this if you have a s-vid switching receiver. You will notice it this way. It seems at first the composite is the same because it brightens the picture but the jitter is still there. I did this about a week ago to compare the difference. When I turned the receiver on the s-video would take over and when I turned the receiver off, the composite input took over. I noticed a huge difference this way with the jitter especially.

#8 of 10 RyanDinan

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Posted December 13 2001 - 04:29 AM

Quote:
What you are really seeing is a "reduction in imperfections". SVideo does NOT improve the sharpness/resolution/information.

Actually, S-Video can handle a bit more color resolution than composite (140 lines compared to about 120 lines). I know it's nitpicking, but hey Posted Image
Luminance resolution should be the same (not limited by the cable) with composite, S, and component.

-Ryan

#9 of 10 Barton Lynch

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Posted December 13 2001 - 05:12 AM

My advise. No matter how great a comb filter is, use the S-video cable insted of the conventional composite. You see even the best 3D Comb Filters add some softness to the finest details such as skin textures due to the separation of the Y/C signals combined in the composite cable. Comb filters are good for sources of composite video -like LD and VHS- but with digital based sources like DVD and DSS, it is better for them to use S-video, or component if it's available. Just my two cents.
Barton Lynch
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#10 of 10 Ted Lee

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Posted December 13 2001 - 05:25 AM

thanks for all the replies guys!

since my receiver does not have s-video capability, and since the picture improvement isn't significant enough, i think i may stay with composite.

the only reason is if i use both composite and s-video, everytime i watch a dvd i'll have to plug in the s-video cable, then when i watch anything else i'll have to unplug it (since all the composite video is going through my receiver) and the tv auto-switches to the s-video input.

that's just too much hassle for so little improvement.

i suppose this'll be a good excuse to buy a new receiver? wink-wink, nudge-nudge...

Posted Image