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Discussion Starter · #1 ·
This is probably a dumb question but I'm prety sure someone here can answer it factually.


I've commented on the fact that I notice the same channel running through the HD output of my 6000 does not have the posterization (color banding) that I have if I switch over to S-video or composite. I also notice that I don't get as much of it if I view on my bedroom set which is fed via RF and is an older Sony.


It occurred to me that the HD input does not go through the line doubler in the monitor whereas the composite and S-video both do.


So, the question is this:


Is it possible that something in the line doubling process either produces or enhances the banding? I have tried to understand how these circuits work and it appears to me that there is a possibility that it could introduce this kind of effect if it is given a digital source that has some artifacts.


Would anyone like to comment on this? Am I totally misunderstanding the technology?
 

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Please list all the equipment you are using.


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Discussion Starter · #3 ·
Ok, Ken. Should have thought of that....


Monitor is a Princeton Graphics 2.7AV, which has a built in line doubler.


Video sources are Echostar 6000 w/8VSB (RGB, S-video, composite), Echostar PVR501 (S-Video, Composite), Hughes E11 DSS receiver (S-Video, Composite) and Apex 600A DVD player (S-video, Composite). I have the standard resolution video sources going through a Sony AV receiver of recent vintage (can't remember the model number offhand) but I see the same thing if I bypass the Sony and go direct into the monitor.


I have also used this with a Scientific Atlanta 2100 digital cable box (S-video, composite) and seen the same posterization on the digital channels only but not on the analog channels.


I have also had the system hooked up through a computer with an ATI All In Wonder Radeon video card and looped the monitor output of the Sony through it to get rid of the problem. This was before I got the DSS setup and was the only way I could stand to watch HBO on the digital cable setup.


So, what I can say is that I never see the banding if I am feeding the monitor through the VGA input. It doesn't matter what the source is or even if I am just looping a composite video source through the computer. I never get it with VGA or using the 6000's HD output as the source.


The amount of posterization I see varies from unwatchable (digital cable) to tolerable (DSS) to variable (DVD) and I see it with both the S-video and composite inputs. I am not convinced of this but I think it is a little less with the composite, maybe because it is a little less sharp.


So, it makes me wonder. What is different? I am assuming that the VGA input isn't line doubled and the video inputs are. I know there are digital artifacts in DSS video because of the compression but I am wondering if there is something that the line doubler does which exaggerates it.


If that is the case, I would love to find a way to turn off that feature. I think I would rather see scan lines (which aren't that big an issue on a set this size) than have people look like they have a skin disease.


Your thoughts?
 
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