Horizontal streaks in high contrast areas?
I see these horizontal streaks when capturing analog sources. They're most obvious during title sequences, and more visible on VHS than LaserDisc.
Is there a name for this, and what's the cause? Any way to reduce the effect? Here are a couple of screen caps from a LaserDisc to illustrate the problem. I lightened the first image up a bit to make the problem clearer and put some nice red arrows in there to point at what I'm talking about. http://www.digitalfaq.com/forum/imag.../BYhx1Lj-1.png http://www.digitalfaq.com/forum/imag.../klRh0nw-1.png Thanks for any tips! |
It's ghosting, and is usually caused by a VCR or other hardware (the Elite Video BVP4+ can do this). It tends to be very tape specific, and the source recorder of that tape can cause it.
What does your workflow look like? (list out hardware in use) |
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However, I've tried different sources (different LD player, a VCR), tried s-video vs. composite, tried different capture cards, and different discs/tapes. The ghosting is always present to one degree or another. I was wondering if there's a general-case way to reduce ghosting (e.g. better cabling, video processor, etc.) |
The capture card is likely to blame. I've never liked Osprey cards for capturing. Yeah, they're expensive, but it's not uncommon to see $100 cards outperform $1,000 cards, when it comes to video. Some companies just cannot get the chipsets to behave.
We have the same problem with TBCs. |
I'm actually returning the Osprey card because it didn't seem to produce better results than the cheap ATI TV Wonder 750PCIe card I tested against (though I'm aware that the ATI has AGC issues).
I'll be testing a Matrox MXO2 Mini next week. |
The MX02 should do better, though I forget which MX02 was good. Are there several? It's been a while.
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There's the MXO2 Mini and the MXO2 LE, but the second one is a bit out of my price range. I'll keep my fingers crossed on the Mini...
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You need to invest in a high-end LD player to avoid it on CLV discs: http://notonbluray.com/blog/laserdisc-clv-smear/
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I wouldn't say that's the same effect at all. The type of smear created by sharpening, haloes, or blur would be very localized horizontally. The effect the OP shows seems like a much longer term effect. I have an idea that it might be related to AGC, perhaps your capture card thinks the white/black is out of range and resets it's range to compensate. It seems like one could write a digital filter to undo the effect since it looks consistent. I might look at it.
For me to do this perfectly, I'd need you to play a DVD file to your capture card and send me the uncompressed capture of it, I can make every possible change in shade and simply undo the effect. |
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