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Discussion Starter · #1 ·
I'm trying to improve the picture I'm getting from DScaler...


I recently replaced my s-video cables with BetterCables silver serpents. These cables showed a *very* good improvement in my picture that was not subtle. For a TV signal, the picture is suprisingly solid. However, I'm still experiencing one artifact that was not eliminated by the cables.


BTW - I am familiar with the common "noise" seen when using these capture cards (i.e. the "storm" look on dark background that can be reduced by using the Noise Reduction Filter)... This is NOT that problem.


This is difficult to describe, but here goes:


First with the adjectives... The image is "rolling", "wavy", or "swimmy". It's as if the surface of my screen were liquid, with a subtle ripple slowly rolling up the screen. This "wave" or "bar" is in fact invisible, regardless of the background color. It's effect can be clearly seen though - letters of text or graphics bars "shimmy" back and forth subtly and slowly.


I have experienced "hum bars" caused by ground loops in the past and have eliminated their possibility by ensuring that all my equipment uses a common ground (plugged into same circuit). Those bars were quite visible and large; the effect I'm seeing in DScaler is not what I've seen from a ground loop caused by plugging in equipment to different circuits (e.g. HTPC into one wall socket, projector into another).


I have ruled out my cable box, external DVD player, and A/V Receiver as culprits. All of them exhibit this "waviness" when connected directly to my capture card via S-Video.


The only commonality between my test scenarios is the HTPC w/ capture card and DScaler. This rolling is only in DScaler, and not my projector. The rolling can be seen inside the DScaler window when not maximized.


Is this a form of interference and can it be tamed? Or could this be an unavoidable artifact of de-interlacing a crappy signal? I doubt the latter, because regardless of which de-interlacing method is used, the effect is identical.


-Jeff
 

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What Svideo capture card do you use? It may be interference inside the PC on the card. Sounds electrical to me. Try shielding the card with some self-adherent aluminum foil tape (saran wrap the card first and then stick on the aluminum foil tape to prevent shorting of electrical components--allow heat to escape by not sealing the top edge of card). Otherwise you may have to shell out more money on another Svideo capture card.
 

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Discussion Starter · #3 ·
Thanks for the reply Huey... I'm using the Pinnacle Studio PCTV Pro.


I am willing to try another card if I have to - perhaps a "capture only" model without a tuner (could that help)? I will definitely try insulating the card from interference. I agree it sounds electrical... The consistent speed of the rolling "bars" remind me of ground loop induced hum bars, but they are much more subtle.


I'm no eletrical guy, so I don't know if this is valuable, but here's an interesting note (maybe)... I have a "volume knob style" potentiometer installed on both on my HTPC's power supply fans. One came on my Enermax PS, the other I installed myself (replaced its thermistor with volume knob style pot). The only reason I mention this is because I recall reading that a "light dimmer switch" on a home electrical circuit can cause hum bars on televisions. My pot's are essentially "dimmers", aren't they? (just DC instead of AC). dunno - shot in the dark...


-Jeff
 

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Trying a video only card might be a good idea.


I originally bought a Cybertainment card with TV Tuner when they were popular around here from Compgeeks. The noise was kind of bad on the video inputs and the tuner stank (unsuprisingly.) I then picked up the same brand, video only card (hey, $14) and it worked/still works now very well.
 

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Quote:
Originally posted by jmccloud
First with the adjectives... The image is "rolling", "wavy", or "swimmy". It's as if the surface of my screen were liquid, with a subtle ripple slowly rolling up the screen. This "wave" or "bar" is in fact invisible, regardless of the background color. It's effect can be clearly seen though - letters of text or graphics bars "shimmy" back and forth subtly and slowly.


I have experienced "hum bars" caused by ground loops in the past and have eliminated their possibility by ensuring that all my equipment uses a common ground (plugged into same circuit). Those bars were quite visible and large; the effect I'm seeing in DScaler is not what I've seen from a ground loop caused by plugging in equipment to different circuits (e.g. HTPC into one wall socket, projector into another).
This still sounds like a hum bar to me, just a less extreme example of it. Ground loops are not only caused by having two pieces on different circuits, or having different paths to ground, but by different potentials on the chassis of the two pieces of equipment. The way to find if this is the cause is to disconnect every piece of equipment, all power and signal lines, and then hook up the bare minimum...for instance, your HTPC and projector. If that is clean, start adding bits one at a time.


Did you add this electrical service specifically for your home theater? If not, you may be amazed at how bad the electrical ground at your outlets is. All the money audiophiles waste on special AC cords and recepticles would be better spent on larger gauge Romex and having a decent grounding system built.
 

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Discussion Starter · #6 ·
Thanks Chris - like I said, "I'm no elecrical guy" :)... Unfortunately, I rent and am not inclined to get electrical work done on someone else's house.


Yes - I agree, it does look like a mild and invisible hum bar. My only thought is to try moving the cards around in the htpc.


I will try your suggestion about stripping down the components. The bare bones setup would have to be htpc, projector, and at least one other S-Video source (A/V Receiver, Cable box, or DVD STB).


I just thought of one other ground loop possibility, but I'm not sure if this could occur. All home theater stuff appears to be on one circuit. However, a second machine is connected to a hub so that we can use our cable modem connection in another room. If that lan connection "counts", *techincally* not all of the equipment IS on one circuit after all... I will try disconnecting that other PC as part of my testing.


-Jeff
 

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I had a similar problem...herringbone interference on my PCTV Studio Pro. As a last resort I put in a Monster Power Conditioner (HTS1000) strip. I was very suprised when this cleared the problem up. Normally I am very skeptical of Monster products, but this seemed to do the trick.


Relatively expensive solution at $200, so I wonder if there is a cheaper alternative.


YMMV!
 
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