Quantcast Horizontal streaks in high contrast areas? - digitalFAQ Forum
  #1  
08-16-2015, 12:18 PM
oscarfowler oscarfowler is offline
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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.




Thanks for any tips!
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  #2  
08-16-2015, 12:37 PM
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lordsmurf lordsmurf is online now
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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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08-16-2015, 12:49 PM
oscarfowler oscarfowler is offline
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Quote:
Originally Posted by lordsmurf View Post
What does your workflow look like? (list out hardware in use)
In this particular case, I was going from a Pioneer CLD-R7G -> composite -> Osprey 210e PCIe capture card -> VirtualDub capture

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.)
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  #4  
08-16-2015, 12:55 PM
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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.

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  #5  
08-16-2015, 12:59 PM
oscarfowler oscarfowler is offline
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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.
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  #6  
08-16-2015, 01:02 PM
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The MX02 should do better, though I forget which MX02 was good. Are there several? It's been a while.

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  #7  
08-16-2015, 01:07 PM
oscarfowler oscarfowler is offline
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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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08-31-2015, 12:48 PM
msgohan msgohan is offline
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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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  #9  
09-01-2015, 12:08 AM
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Quote:
Originally Posted by msgohan View Post
You need to invest in a high-end LD player to avoid it on CLV discs: http://notonbluray.com/blog/laserdisc-clv-smear/
Text copied for your convenience:

Quote:
Laserdisc CLV Smear Myth or Reality ?

CLV Smear is often mentioned when discussing laserdisc players. I’m currently in the process of writing an enormous article comparing various NTSC comb filters. As part of that I’ve been comparing my various Laserdisc players. After reading about CLV smear I wanted to explore it a bit more and confirm a few facts. I can best describe CLV smear as a tendency for high contrast areas to faintly smear to the right during playback of CLV discs on most Laserdisc players. I’ve seen this being attributed to high frequency boosting applied to the signal from CLV discs by players to increase high frequency response. This boosting is generally not applied to CAV discs (except at the very start) since the high frequency response is generally much better. So – Is CLV Smear real ? Does the player make a difference ? Is it baked into the disc ? Read on…

CLV Smear – Myth or Reality ?

Well the answers are pretty straightforward. By reputation the Pioneer HLD-X9 doesn’t exhibit CLV smear, and I am fortunate to have access to one. Additionally I managed to resurrect my Faroudja LD-1000, an upgraded Pioneer CLD-99, for comparison purposes. Both are fine players, with the LD-1000 often being described as the best US market player, while the HLD-X9 is arguably either the best or second best player Pioneer ever made. My capture chain, which I’ll cover in more detail later is Laserdisc Player -> S-video -> Leitch DPS-575 (TBC/ADC) -> SDI -> Blackmagic Hyperdeck -> SSD. Alien is an awesome film, and the AC-3 Laserdisc has a 70mm soundtrack that simply isn’t available on DVD or Blu-ray. The high contrast title sequence gives us an excellent showing of CLV smear in action.

Conclusions

It’s real. My Faroudja LD-1000 does it. I believe many other Pioneer players also exhibit it. I’ve read that the Panasonic LX-900 is smear-free, so may be worth a look. The Pioneer HLD-X9 is definately smear-free, but is a little awkward to buy outside Japan.
Example image attached:


Attached Images
File Type: png CLD-Smear-CLD99-vs-X9.png (331.5 KB, 18 downloads)

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  #10  
09-01-2015, 06:10 PM
jmac698 jmac698 is offline
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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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