Interference on capture. LordSmurf? EE Majors?

[tito13kfm]

I have posted this question once before and received no response, but now I have more info.

When going from my JVC 30K to my canon camcorder (being used as a ADC) I get strange interference that appears as bright lines that travel up the screen, reappear at the bottom and start over. I do not get this interference when capturing from any other device through my camcorder.

Also, the video captured from the JVC seems to have muted colors, notice the blacks aren't truly black, and the whites aren't truly white.

Here is a picture of the stream from the jvc


Here is a picture of the stream straight from the source


Note: This does this whether capturing from a VHS tape, cable broadcast, or any other device that gets routed through the JVC 30K. And I can see the interference/noise on the camcorder preview screen so it is definately not a computer issue.

Is there something wrong with my unit? Is this some sort of electrical interference? (I have tried using shielded S-Video cables as well as monster composite cables) What can I do to help this situation, as this really sucks when I'm trying to convert my VHS collection to DVD and I get these lines running up the screen the entire time!

[SatStorm]

Those lines are the flows of any analogue capture. Only shield PCs on shield houses with shield cables and High End VCRs can eliminate them.

The cheap alternative: Use a filter in the post capturing proccess. For lines like those, dynamic noise reduction @ 8 or temporal smoother @ 3 is more than enough to eliminate them, with minimum picture loss. Using sharpness at 3 or 4 also restores any sharpness might lost because of the filters....

[tito13kfm]

Thank you for the info, I do not doubt that you are most likely correct, as you have given me good advice in the past, in particular in the thread about the BTWincap Drivers and what resolution to capture at, but why would they only appear when capturing from my $400 DVHS JVC VCR (as well as the washed out color), when they do not appear when capturing from a Playstation, or even a crappy garage sale $5 VCR.. GRRR..

I'm sorry if I sound like an ass.. it's just i've been up since 1am trying to figure this out..and it's 6:30am now.

Edit.. 1 more thing, If I first record the video to DVHS, then recapture this via firewire to the PC it does not show either. It's as if the interference is being introduced in the line out of the VCR. Are there any good filters that can combat this? (Physical ones, something along the lines of a low-pass filter, but for s-video)

[SatStorm]

When you use firewire you are doing dv transfer, you don't capture...
It is a totally different thing.

Those lines are always there with analogue captures, but we mostly can't see them! You see, they change from field to field, so they are "invisible". Only if you load your captured avi to virtualdub and roll frame by frame you gonna detect them with your eye.

Your DVHS output more info to your card than your cheap VHS VCR. More info means that it is capable to show more details, the cheap VHS can't even output. More info also reveals the flows of the recordings...

A parallel example:
If you output VHS to a TV it might look okey. Now output the same VHS from the same VCR to a good videoprojector. It looks like shit. Same story here...

Playstation also output lower resolution, with many info lost. That smooths the picture and shows better in your eyes (not in reality)

If you capture from your DVHS using S-Video @ 704 x 576/480 and use couple of filters then resize to 352 x 576/480 and encode using TMPGenc to mpeg 2 (with CQ for example, 2000min 8000 maximum), the results you gonna see from your DVD player gonna be intentical the source, but in really low filesizes! This is all about, better compression, less artifacts.


VHS tapes are 352 x 240/288 lines, but they are using a 352 x 576/480 carvas, that's why we capture at that framesize. When you capture higher it is overkill and that is well known. What is less known, is that if you output VHS from devices which by default outputs more than 352 x 576 (SVHS framesize), this example here is DVHS, it is also an overkill and this time, you can't do anything than filtering it!
Or capture it from a device which output a lower resolution.

[tito13kfm]

I am just trying to bypass the whole capture with huffyuv, apply filters, frameserve, encode process.

I was really hoping I could use the MainConcept encoder to capture the DV and do on the fly encoding to MPEG. (It's possible in the newest version as far as I know)

I truly think that this whole more information is giving me a worse picture doesn't hold water (i'm stubborn). I can't understand why the color would be so horrible in the feed from DVHS, but be spot on in the capture from Playstation. Also when capturing just the Grey menu screen of the vcr itself the distortion/interference/whatever is still there.

I would love to hear if LordSmurf sees these lines when capturing from one of his high-end SVHS players, or if this is just something with JVC's DVHS units. It is my theory that perhaps JVC has a faulty comb filter built into the vcr, or maybe this noise/interference is coming from another source (the VCR is plugged into a power strip with 6 other devices on it).

When I wake up I am going to take every variable out of the equation, I will plug the VCR into a seperate circuit. Turn off and unplug all devices not in use in the room. Remove my cell phone from the room. Capture the Grey menu screen. If it is still present then I will be returning this unit as it is of no use to me if I can't get a capture that I don't have to heavily post-process.

[SatStorm]

Please: Next time, add to your post's title which members of this forum you wish to answer you.

Meanwhile, I'm promising never to interfier to your posts again.

[tito13kfm]

@SatStorm - Be sure that you don't, nudge nudge wink wink (it's so hard to capture sarcasm in text)

@LordSmurf - Have you noticed any of these symptoms when capturing from your SHVS players?

[FOO]

How is your camcorder powered ? Have you tried running it on
internal battery ?
Slowly moving noise is usually related to 60Hz power line noise
which is almost but not quite the same frequency as the vertical
refresh (or sample) rate of the video. The VCR may have a noisy
power supply.

Does your VCR have a splash screen ? Does the problem show up on that ?
(no tape)

Sometimes a filtered power strip will reduce stuff like that , especially if
the outlets are individually filtered .

[lordsmurf]

FOO said some of mine already. Get a UPS with AVR for your computer AND the video stuff

The blurry image is most likely your capture card. Unless I missed something. I don't know which is is which, nor how it was made.

Up-down lines I see from my TBC if it's hot. Maybe from JVC if it really hot and overused. No side-to-side lines, that's power or coax noise usually (see that on my unfiltered ATI card in 2nd system).

Good call on cell phone. Mine causes problems.

I know this sucks, but I need more details, spare none. Write a novel if needed. I'll browse it.

[tito13kfm]

No side-to-side lines, that's power or coax noise usually

HAHAHAHAHAHHAHAH!!! THANK YOU!!!! LordSmurf wins Genius of the Year award!!

I disconected the coax cable from my VCR and BINGO!! The interference INSTANTLY disappeared. Also the color is more accurate and the picture appears a little sharper.

Sorry for all the yelling but I'm happier than Michael Jackson at a sleepover.

Thank you Foo.. Thank you LordSmurf, Thank you SatStorm..

Now here comes my follow up question, Can this noise be filtered out of the Coax line? If so, does anybody have any suggestions as to what type of filter to use?

[lordsmurf]

Play with FM traps and DC blocks.

[FOO]

Do me a favor and just connect the shield of your RF cable to the
VCR and see if it still does it. (without the center conductor )
This will eliminate any signal actually
coming down the cable from causing this and we might learn something

[tito13kfm]

ok.. just touched the shielding to the coax in on the vcr and the distortion came back.. as soon as I move it away it goes away. Also tried it with a short cable run directly from the wall to the vcr with no splits and it still does it.

What have we learned by this?

[FOO]

Looks like the Cable TV shield has a huge harmonic component
of 60 power on it relative to earth ground , enough to overpower
the ground wire in the eqipment power plugs. Surprise , Surprise
the cable hangs underneath the city power for several miles

You still gotta wonder why a common mode signal on the VCR case
turns into a differential signal into the Camcorder or PC.
It's magic. I've spent weeks tracking down things like that to pass
FCC tests

[tito13kfm]

So, If I were to find a filter that would filter out the 60HZ frequency being carried through the cable wire then in theory the interference should disapeer. I already have an FM Trap that I'm going to test out, but it's 9pm, so it's off to the bar.

At least now I know what i'm fighting against.

[FOO]

No , it's not anywhere near 60 Hz , it's a high harmonic of it

one thing to try , if you have a UPS , run the VCR on it without it plugged in
(float the whole VCR) It's not practical to fix the problem , it's just
more evidence to figger it out with

[argiris]

Sometimes these lines appear if the RF signal into your video tuner is just too strong.

1. Are you using some kind of antenna amplifier? If yes, user the trimmer to lower the output signal strength.

2. Is there a channel that has particularly strong transmition? If yes, search for an attenuator that that channel's frequency (see next paragraph)

A good gix may be a RF variable (or fixed) attenuator in series with your coaxial feed from the antenna. If you go for fixed, try 3dB and 6dB, or their combination (They are really cheap). Also some (older?) vcrs had a swich at the back that would attenuate the signal (they have an internal attenuator) Check if yours has one.

[FOO]

Read the posts . It does it with ONLY the shield connected

[argiris]

I've seen the posts. I think it doesn't matter if the just the shield is connected. The shield on the coax is not ground, and the receiving end (tv or vcr) is not ground either. Even if only the shield is connected and the signal is strong enough, you can see it from capacitive coupling. However, I am not trying to look like an expert, just from my experience.

I have the exact same problem on my tv set, where one particular station swamps the nearby channels on the same band. You can see "shadows" of that channel on the background of the others. All solved when I pointed my aerial a bit off-centre to reduce signal strength.

I never had any problems on the equipment I design with CE (FCC equivalent standards) (Now I AM trying to make an impression!! ) (no pun intended - just joking with a fellow engineer!)

[FOO]

Even if only the shield is connected and the signal is strong enough, you can see it from capacitive coupling

Bullshit. I suggest you see if you can receive a cable TV signal
by connecting ONLY the cable shield to the outside if the VCR input connector.

[tito13kfm]

Ok.. I think I might be on to something, The cable transmission is being run to a splitter before going to the VCR. If I was to ground this splitter, would this help alleviate the problem? Ther is a screw built into the splitter for hooking up a ground wire.

What would be the best way to do this? I know absolutely nothing about electricity and grounding, so I don't even know where to begin. If I were to just run a wire from this screw out the side of the house and then onto my fence pole which is buried down pretty deep would this work? Or can I just use the electrical system in my house to somehow ground this? Or am I completely off base here and this would help nothing?

[lordsmurf]

The type of splitter makes a difference too. If it's low quality and cheap, that's the problem.

Get an OFFICIAL splitter from your cable company.

[tito13kfm]

Well the interference also appears when I don't use a splitter, so the splitter isn't causing any trouble.

I tried a RadioShack TV Interference Filter 54-900Mhz but I guess it was filtering out too much as the quality of the picture was horrible, very grainy and the audio was distorted.

I am going to go through all of the filters and see what they have available, I'm sure some combination of them will work fine.

Thanks to everybody for their help, Unless anybody has any more to add I will consider my problem Solved, as in a workaround has been found.

[SatStorm]

Sometimes myself don't understand how many factors affect the NTSC signals!!!

All those things you mention here, simply don't exist with us the PAL users... How you hold up so many years with this system? It has SO many issues....

@tito13kfm:
And when you clear all those interferences (I didn't imagine that exist for those reasons....), then you have to deal with the small lines I first told you, which you probably won't see afterall, or find them minor to deal with. But if you decide to deal with them, you can use the filters I mention. The reasons of the existance of those lines are the reasons I gave before.
But this is after all those matters you have to deal with first...

[FOO]

I would say grounding that splitter would probably fix the problem.
Grounding the case of the VCR would also.
The VCR probably has a 2 prong plug instead of a 3 prong plug with
ground. It would be easier to go to the ground on the wall outlet
if you can figure out how .
The computer probably has a grounded plug , either both or neither
of the VCR and computer should be grounded.

[tito13kfm]

Damn you guys are smart,
I grounded both the splitter and the VCR case by running a piece of wire to a nearby water pipe. Instantly the picture was better..

Thanks again everyone!!