Powerline noise in captured video

[Tperez2]

I was told that i have "powerline noise" in my captured video.

it was suggested that i ground everthing and check my cables.

well i tried 3 different svideo cables including monster thx cables and got the same result

my computer is grounded properly but how can i ground my cable box???

I dont see a ground screw on it and i dont want to make a hole to attach one so what are my alternitives??

[iantri]

Could you provide a screenshot?

[Tperez2]

I could but they are very faint and i only notice them when the video is live I will try to find something where they are more noticeable and post it asap

[DVD_Ripper]

Do you get the same results from the composite cables?
If not it may not be the cables?

[Tperez2]

As far as i know yes i get the same problem with composite cables

[iantri]

I'm assuming you mean you are getting rolling bars in the video when you say "powerline noise" -- do they run horizontally, diagonally or vertically?

Is it a gigantic hum bar (huge bar rolling down the screen; you say it is slight so I doubt it), or is it a series on equally spaced bars where the image is very slightly darker or lighter?

Digital or analog cable? Since you say you used composite cables I see two possibilities:

1. It is digital cable -- you connected your digital cable box to the capture card input. You should absolutely NOT be getting these bars.
2. You are running your analog cable through a VCR -- the VCR may be poorly grounded.

I know you say that it is very slight, but a picture really would help; try and find a scene with a almost completely black or completely white frame and see if it is noticable on those.

[Tperez2]

a series on equally spaced bars where the image is very slightly darker or lighter?

Thats exactly it. I have connected my digital cable s-video output to the s-video in on my capture card

Do you have any idea what the problem is??? And can you tell me how to correct it??

[Tperez2]

Oh im sorry forgot part of the answer

they roll up the screen horizontally


If i connect my cable box rf output to the tuner i also see some diagonal lines as well.

[iantri]

The diagonal lines when connected to RF is just likely the result of a crappy cable (one of those push-on types?).

But the curious bit is the hum bar with S-Video input. Does the cable box have a three prong plug? Are you certain that the outlet is properly grounded?

Is it an ATI card? I've heard this happens more with them..

BTW, IANEE (I am NOT an electrical engineer!)

[Tperez2]

Actually yes it is an ati card. but no the cable box doesnt have a grounded plug.

[upshot]

You may need a "power conditioner"... It will filter your power source of "noise" providing your components with a consistant flow...

they go from $50-$2000 so choose your poison... Well worth it in my opinion cleans up alot of A/V noise....

[iantri]

Also, a lot of UPSes do power conditioning, but some of the really cheap ones don't -- check.. but you might be able to get a cheap UPS that will do it for under USD$50.

If it is possible, try a different capture card. ATI cards (the all-in-wonders) are supposed to be particularly prone to this problem.

[Tperez2]

I have never seen this mentioned about ati cards anywhere on the web. where do you get your information?? i must have missed something that i should have read before i bought this card

[johns0]

I used to get those power bars going up my capture screen till i replaced my winfast tv expert card with a msi tv nowhere card,no bars what so ever so it can be rf noises your capture card is picking up from inside your computer due to poor rf shielding on the capture card.

[Megahurts]

Tperez2

You don't mention if you're in NTSC land. If so then if you have 2 bars rolling up the screen then you have a 120 hz filtering problem.

Do the bars show up on when feeding the same signal with the same inputs to a TV?

Most cable companys provide digital and analog signal, so if you hook the cable to your capture card without the cable box, does it have the same problem?

I suspect the cable box. Let us know.

Chas

[lordsmurf]

How close is the PCI soundcard to the AGP ATI card?
Same for the LAN PCI card?

[Tperez2]

Actually the aiw and the avermedia card are the only 2 cards in the system the rest is on the mother board

[lordsmurf]

I know for a fact that certain VIA all-in-one motherboards are "dirty" and interfere with video cards, seen as noise. I've seen it in three systems to date. Cards were fine plugged into my Intel motherboard.

You've had varying degrees of troubles with all video cards, haven't you?

You're getting into the odd error area now. A cheap power supply could also be leaking junk power into the system. I'm no electrician, but I'm under the impression the raw AC current is fed to the PC and the power supply regulates it to DC for all the computer components. What if this is not well done?

Sort of grasping for straws, but I think this is where you are.

Try the card in a friend's PC or a family member's PC if you can.

I've had all kinds of issues in the past when I moved to the house where I am now. I run off 2 AVR/UPS units (AVR = automatic voltage regulation ... "clean power") and numerous filters on the coax lines. I have my soundcard far from the video card, same for LAN. On my all-in-one board, I gave up, and it's now in an encoder/burning system only. My main PC is free of noise most of the time, and the only time I see it is from the cable signal, and only sometimes.

Some of this is beyond our control.

[Tperez2]

Actually i built the system myself, been a pc tech for about 15 years system is built with an asus p4p800 mother board with intel chip set

have already tried the stock ps and a 400 watt coolmax ps had the same problem with both. the avermedia card had no problems other then mpeg compression artifacts mesquito noise.

I never got the moving bars with the avermeida card only with the ati card. I stll get the bars with the onboard sound turned off ill have to try turning off the onboard lan card as well

[Tperez2]

Turned off all onboard except for hd contorler and floppy controller still get the same bars

one thing i never mentioned but might be related is that when i connect the audio cables from cable box to either cap card i get a huming sound unless i set cable box to maxium volume.


not sure if this has anything to do with my problem

[lordsmurf]

Turned off all onboard except for hd contorler and floppy controller still get the same bars

one thing i never mentioned but might be related is that when i connect the audio cables from cable box to either cap card i get a huming sound unless i set cable box to maxium volume.

not sure if this has anything to do with my problem

Oh yeah... that aggravating-as-hell hum is quite related. This is definitely a power/grounding issue of some sort.

How is this thing with a VCR inputting s-video only (no coax in card or VCR).

[Tperez2]

Actually i dont have a vcr with svideo out the only vcr i have right now is a combo with svideo out for dvd only i guess i can test that and disconnect from the cable system just plug in ac power only. I should have thought of that myself.

[mazinz]

hmmm i seem to have the same issues as the original poster. It happens every now and then but i can still see it. I get a roll bar (horizontal) going up the screen. I just did a capture for someone and did not fully notice it till it was played on the tv. It was blatant enough for me to scrap the disc and do it again (well eventually).

using

dvc 2 (dazzle, pci version) capture card

signal goes through my svhs deck (phillips)
into panny recorder (for its tbc thing)
and then into the dazzle box which hooks into the pc

i do have a sound card (sound balster) and an ati radeon card
I do not h ve much room though to really move the pci cards apart. All the cables used are also monster shielded type.

[Tperez2]

I just did a capture from the svideo out of my vcr/dvd combo unit while disconnecting all connections from cable box and it looks great almost dvd quality bit rate is a little low but no rolling bars and no hum it looks like it is something to do with the cable box


now i just wish i knew how to correct the problem

[Tperez2]

Ok it looks like its a problem with the cable box as soon as i connect the cable box output to the input of the vcr/dvd the huming comes back and so do the bars now is there anyway to filter the humming noise and bars that are being caused by the cable??

[Tperez2]

Ok i found an article which mentions the humming sound and how to correct it. I connected 2 baluns back to back. you know the little transformers that let you use coax with tv sets with 2 screws on the back. well i connected them together and placed them between the cable box and the cable line and it eliminated the humming noise and im pretty sure it got rid of the bars but it also eliminated the digital signal that gets fed to the cable box it did pass the rf cable signal but i only get a few channels that way. so ill have to think of some thing else.

[Werble]

Tperez2, I have the same exact problem with the faint lines rolling up the screen horizontally. My setup is the same connecting my dtv cable box to the svideo input of my MSI geforce III nvidia card (so it's not just ATI cards). I don't get any lines when the dtv cable is connected directly to my tv, just to the capture card. I have always thought that my power supply (enermax) is to blame since the nvidia card is so close to it. I figure the fans (two of them) from the psu may be causing the interference to the capture card. Just a theory so if anybody can support it with actual facts, please let me know. If it is the psu then we are out of luck since agp cards can't be moved further away.

[Bob W]

Be sure to keep any signal cables far away from speakers and those external AC/DC power supplies.

[Tperez2]

Ok I just tightened the ground on the cables coming into the house and unless im crazy things have been corrected im doing a fresh capture just to make sure ill let you know what i find

[Alan69]

well i connected them together and placed them between the cable box and the cable line and it eliminated the humming noise and im pretty sure it got rid of the bars but it also eliminated the digital signal that gets fed to the cable box it did pass the rf cable signal but i only get a few channels that way. so ill have to think of some thing else.

Back to back baluns have a lot of loss of bandwidth so that's where your digital went.

Temporary test, attach the cable into the box, but only the center conductor. Keep the outside screw conductor not touching the screw on the box. If the center conductor is cut short so you can't do this easily, stick a 1" piece of wire or small paper clip into the center hole in the cable input plug, then just touch the center wire from the cable to this piece of wire, making a temporary extention. You'll get leakage from the open shielded conductor, but you should get no noise without the baluns since the two grounds aren't connected.

Try the above first and then we'll go from there. Basically, either your house electrical system or the cable shield at the cable box outside your house aren't tied to the ground rod correctly, or the ground rod is not earthed well. Quite likely the cable people didn't even bother to tie their stuff to the ground rod, they often just assume the one out at the street will be enough. Any of this will make for ground loop currents, and that's your power line hum on screen.

You can also disconnect your cable from the box, and put a voltmeter from the ground hole in a socket to the outer shield of the cable. You should see a small AC voltage between them, that's the difference in voltage, and they're both supposed to be tied outside to the ground rod. Very dangerous too if it's your mains ground connection that's bad and not the cable box.

Alan