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Ghosting

Old 11-25-02, 01:05 PM
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Ghosting

I'm running component from DVD player directly to my front projector, and I'm getting what I'd consider to be significant ghosting. Even my g/f noticed -- she asked why everyone looked like they were wearing retainers.

The cables are 50 feet, and passed diagnostic tests from my HT store.

Any ideas? Thanks in advance...
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Old 11-25-02, 02:03 PM
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Have you tried shorter cables just to see how they look?
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Old 11-25-02, 02:42 PM
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Originally posted by X
Have you tried shorter cables just to see how they look?
Yeah, I knew that was coming. I was planning on doing that when I got home tonight, but I don't have any other cables made _specifically_ for component video, so it might not be a good test.

When I measured the required length of the cables, the HT store assured me that the length wasn't an issue with high quality cables.

What would cause ghosting? Cables too close to big magnets? Running near computer equipment? I'm doing both, and will relocate the cables as an additional test.
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Old 11-25-02, 03:14 PM
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Ghosting is usually caused by RF interference, I believe.
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Old 11-25-02, 03:23 PM
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Or could it be signal reflections caused by impedance problems resulting from such a long cable?
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Old 11-26-02, 12:24 AM
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I'd definitely try it with a 6' cable if possible, just to see if the condition exists even then. Also, 50' feet of cable... where is it running to and from, and where? If in the wall, it's possible it's to close to your houses electrical wiring, which could and would cause ghosting.
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Old 11-26-02, 10:42 AM
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Okay, it's not the cable. I borrowed a 4 meter cable ($120 value) from the store, and the problem still exists. I positioned the DVD player on a table under the projector, so there aren't any objects near the cable.

Can something be wrong with the DVD player? Or maybe DVDs in general just aren't that good and a high end front projection system just exposes the flaws that an "ordinary" tube cannot?

I'm bringing the DVD player into the store just to see. Or maybe I'll take home a loaner player...
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Old 11-26-02, 11:39 AM
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Originally posted by DarkElf
Okay, it's not the cable.
That's good to know. Of course that's also probably the cheapest part of your setup.

Have you used the projector before? That seems the most likely source. I've never noticed anything that looked like ghosting from using many different players or DVDs.

Have you got your projector set up to its preferred resolution and refresh rate? Even a computer monitor having these parameters set improperly will show ghosting. Especially a too-high refresh rate.
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Old 11-26-02, 11:26 PM
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Another update...

I brought my DVD player to the stereo store and did a comparison with a fairly high end NAD player on Hitachi's best rear projection.

Whatever ghosting I saw on my DVD player, I also saw on the other one.

It isn't the cables. It isn't the DVD player. It isn't MY projection system. And the problem wasn't nearly as noticeable on the rear projection system. I'm beginning to think that DVD, once a panacea of high end home video, isn't all that. So yes, X, I'm blaming the source. I'll be calling Yamaha customer support soon just to see what they say. It seems that this problem just doesn't show up until you get to pretty high end stuff.
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Old 11-26-02, 11:29 PM
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What was the DVD? Where does Yamaha fit in here?

I don't see how you eliminated your projector here. It just wasn't as noticable on a RPTV? Is that it?
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Old 11-26-02, 11:38 PM
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Originally posted by X
What was the DVD? Where does Yamaha fit in here?

I don't see how you eliminated your projector here. It just wasn't as noticable on a RPTV? Is that it?
On my system, I've tried several, including Video Essentials.

At the store, the Superbit version of The Fifth Element.

But I also see the same ghosting when any on-screen function is displayed. So I guess it isn't the DVD discs per se, just DVD video in general.

I eliminated my projector (I think) by seeing modest ghosting on a rear projector, but it wasn't as noticeable. But the resolution isn't as good. Edge definition isn't nearly as good. I think that's why I didn't really notice it that much, or it didn't bother me before.

Yamaha -> My entire system (except speakers) is now high-end (albeit a few years old) Yamaha...

Last edited by DarkElf; 11-26-02 at 11:40 PM.
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Old 11-26-02, 11:43 PM
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Something doesn't seem right here. I don't have a projector but I've seen pictures people have made of their projected images and read quite a bit about them and never heard this as a normal condition.

However most of the reading I have been doing about projectors involves HTPCs because they almost always seem necessary to get the scaling correctly matched to the projector. Either a HTPC or a good scaler. I wonder how much your projector likes 720x480. I'd tend to think it doesn't and the scalers in projectors normally suck.
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Old 11-27-02, 12:03 AM
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Well, here's the rub. We first noticed (or rather, was bothered by) the condition by people smiling and wearing a "retainer".

But really, forget the DVD disc. Turn on the DVD player, press open, and you'll see ghosting with the "Open" being displayed on the screen.

It may be that I'm just too damn picky, or sensitive to this kind of stuff. I showed the guy at the store what I was talking about and he apparently just never noticed it until I pointed it out.

Do I pay to have a tech come to my house, just to say, "Dude, you're being way too picky?"

But as I said, I'll call Yamaha and see what they have to say. If that proves fruitless, then the store will send a technician. I sort of feel silly b/c people think I should be happy with the 92" screen, but the ghosting (or at least what _I_ consider ghosting) just bothers me.
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Old 11-27-02, 12:20 AM
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No matter what your player is putting out, the menu, a DVD, whatever, it's in 720x480. I have a really strong suspicion your projector is not natively 720x480. So you need to scale the signal to match your projector, whatever it is, 800x600, 1024x768, etc.

If you don't give it a signal that exactly matches its sweet spot it will have to do the scaling for you. Have you ever seen a 1024x768 LCD driven at 800x600 or 640x480? The signal doesn't match up with the pixels and it does its best. But it ghosts. Projectors have notoriously bad scalers built in.

The solution is to use an external scaler that takes the 720x480 signal and electronically scales it to match what the projector expects at its optimum resolution. A HTPC can act as a very good and inexpensive scaler. I think that's where you'll find viewing nirvana.

And as for your being too picky, I doubt it. I do plenty of reading where people complain about problems with tiny changes caused by incremental versions of video drivers. I do that even on a 53" RPTV. If ghosting were their problem they'd have way more to complain about.
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Old 11-27-02, 05:14 AM
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Ah, I get you. Yes, it is native 1024x768.

So are you saying that unless you have a TV/projector that is 720x480, or a high quality scaler, you're bound to see ghosting with the DVD player?

So I don't know anything about HTPC. Can you give a quick rundown on what it does, and how you use it?

Thanks for you answers so far.
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Old 11-27-02, 10:19 AM
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Elf, what projector are you using?

DVDs look terrific on my NEC LT-240 at the same resolution.
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Old 11-27-02, 10:22 AM
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I haven't got time for a complete HTPC rundown right now but for a test you could try hooking up a computer set to 1024x768 directly to your projector via VGA. See if you see ghosting. Then try changing the resolution to 640x480 and see how it looks.

The HTPC is essentially a computer with a DVD-ROM and a decent video card that allows custom resolutions to be set. It might be really easy for you since your projector handles a standard video resolution. Your video card will do the scaling from 720x480 to 1024x768 much better than your projector. And you can also put in a TV (standard and HD) tuner.
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Old 11-27-02, 01:48 PM
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Originally posted by Josh Z
Elf, what projector are you using?

DVDs look terrific on my NEC LT-240 at the same resolution.
Yamaha DXP-1

http://www.yamaha.com/yec/products/video/DPX1.htm

Last edited by DarkElf; 11-27-02 at 02:13 PM.
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Old 11-27-02, 02:03 PM
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Originally posted by X
I haven't got time for a complete HTPC rundown right now but for a test you could try hooking up a computer set to 1024x768 directly to your projector via VGA. See if you see ghosting. Then try changing the resolution to 640x480 and see how it looks.

The HTPC is essentially a computer with a DVD-ROM and a decent video card that allows custom resolutions to be set. It might be really easy for you since your projector handles a standard video resolution. Your video card will do the scaling from 720x480 to 1024x768 much better than your projector. And you can also put in a TV (standard and HD) tuner.
That's a good idea. I think my monitor's video cable is permanently attached, so I might have to find a cable.

I don't have a DVD-ROM drive in the PC, nor can I set custom resolutions. Hey, it's a 3-4 year old computer.

But just looking at the desktop should be a good enough test, right?
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Old 11-27-02, 02:06 PM
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Originally posted by DarkElf
I don't have a DVD-ROM drive in the PC, nor can I set custom resolutions. Hey, it's a 3-4 year old computer.

But just looking at the desktop should be a good enough test, right?
Sure, the desktop should be fine. Although it probably will look worse than a DVD picture would due to its precision and what you're used to. But the relative difference should be evident. I see it on my LCD monitor when I don't use its native resolution.

I hope your video card can just do a couple of resolutions for you to try. The ones I suggested are very standard. The only problem you might have would be with the refresh rate. I'm not sure but you might want to try 60Hz.
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Old 11-27-02, 02:16 PM
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Originally posted by X
Sure, the desktop should be fine. Although it probably will look worse than a DVD picture would due to its precision and what you're used to. But the relative difference should be evident. I see it on my LCD monitor when I don't use its native resolution.

I hope your video card can just do a couple of resolutions for you to try. The ones I suggested are very standard. The only problem you might have would be with the refresh rate. I'm not sure but you might want to try 60Hz.
I know it does the 3 standard resolutions, 24-bit color and various refresh rates.
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Old 11-27-02, 02:26 PM
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Originally posted by DarkElf
I know it does the 3 standard resolutions, 24-bit color and various refresh rates.
Fine. And don't be afraid to try different refresh rates as long as they're within the limits of your projector.

I've heard that exact multiples of the frame rate of DVDs, 24 frames per second for movies, is the best refresh rate to use if your display device can do it. So 72Hz might be your best choice if you ever do go with a HTPC.

You may have to fool Windows by telling it you're using a monitor with a wide range of settings such as the Sony GDM-W900. That's the one I use to open up all the possibilities to my video card.
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Old 11-27-02, 07:26 PM
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Right click on the desktop and click settings and then you should be able to change the resoultion. I have never seen one that wonts to 640x480.

I am not big in the projection stuff. But I have seen excellent setups at show with dvd on DLP. So I think X is on the right track.
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