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Discussion Starter · #1 ·
Im buying a new Panasonic flat screen 28inch widescreen TV next week. The TV comes with a Digital Comb filter and noise reduction. I have a Pioneer CLD D925 player. If I use the S-video will it improve the picture than my standard TV with without a digital comb filter?


Is the comb filter on the TV similar to the 3D Y/C seperation on the elite players?..
 

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Here is some of the info on comb filters. Basically yes. Comb filters tend to remove noise. I noticed a differance when I went from a 25" old Mit to a 36" XBR with the comb filters. The 3D are better filters. Note: do not get mixed up by buzz words that the sales guys come up with to sell stuff. Good luck and enjoy your set!


From Panasonic site


"3-LINE DIGITAL COMB FILTER

This digital comb filter provides an extremely accurate means of separating color from black-and-white in the television signal. Working with three lines of picture information, the 3-line digital comb filter removes both horizontally and vertically hanging dots, as well as dot crawl. "


"3D Y/C DIGITAL COMB FILTER

The 3D Y/C digital comb filter performs field-by-field comparisons of the television image to accurately separate the color from the black-and-white information. The filter works to minimize both horizontally and vertically hanging dots, as well as dot crawl. "
 

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Oliver, you are correct in your assumption. The comb filter does the same thing as s-video which is to separate the Y and C components of a composite output.

If the comb filter is better than the s-vid output of your player than it will be better to go thru composite and rely on your TV's comb filter. I doubt it though so you should be able to get a better picture from your player thru s-vid.

Only way to know for sure is to test it yourself. This may be a worthwhile excercise as the cables are not too expensive and you'll know the answer once and for all.
 

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Discussion Starter · #4 ·
Thanks for the information. At the moment my Hitachi TV has noise reduction and Im running through s-video. When I run the LD through composite the image is alot darker and there is some dot crawl on films like Superman II mostly on his cape. So when I use the s-video the colours are not as vibrant but the image holds up better but you have to adjust the brightness and colour setting to get the best picture. My player has a HQ curcuit which I think has only appeared on European models, what it does is soften the picture like S-video would do to a composite image.


So you think I used run the LD through composite on the new telly and let the TV work its comb filter?.
 

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Which model is this? I'm assuming it's a PAL television.


I've yet to see any PAL consumer equipment with a full 3D Y/C filter. All the 'digital comb filters' I've seen have been 2D filters. This, I assume, is becasuse it's easier to separate colour in the PAL standard and so a 3D filter isn't really needed to produce acceptable results. Of course, we want to play NTSC stuff too...


Your 925 has a digital 2D filter already, so I'd be surprised if you saw any great difference between using the composite or S-video connections. The best test is the Snell and Willcox zone-plate from Video Essentials, if you have that LD.
 

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Discussion Starter · #6 ·
There isn't much difference, composite has alot more richer colours and the S-video seems to smoothen the image slightly. So when I get the new TV do you think the digital comb filter will help improve the 2D filter on the 925?.


I spoke to the chap at Robert sales and he said Sony and Panasonic make the best TV's that they had to offer. Sony seem to charge alot for there TV's I suppose most people want to buy it because of the name. So I went for the Panasonic because it was at a resonable price and had good features.
 

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You can only use one comb filter, you'll have to decide whether the one in your TV is better than the one in the 925.


As a matter of policy I'd turn off all the noise-reduction stuff and the 'HQ circuit' on your player. These are really just various types of filters that degrade the image and aren't needed on a properly produced LD.
 

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Hmmm... maybe I've misunderstood, but I thought the advantage to using S-Video with DVD is that in the MPEG domain the color and luminance information is stored seperately, so by using S-Video out from your DVD that information is never combined and is therefore cleaner.


Am I to understand instead that the DVD player seperates Y/C in the analog domain??


Gabe
 

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So I see some misinformation in the thread and I hope I can clear some of it up. I have not read all of the posts in detail so I am sorry if I repeat what has been said.


A comb filter is ONLY used when you feed a composite or RF signal into the TV. A composite signal has the luma (Y) and chroma (C) information combined. The job of the YC sep is to split them apart. Once combined, there is no perfect way to every split them. By this time you have lost both luma and chroma resolution and you have introduced new artifacts called dot-crawl and cross-color.


A DVD player starts life as a component signal. Here you have 1 Y and 2 chroma channels. The chroma channels are combined for the YC output and the luma and chroma are combined for the composite output.


For DVD and DSS, you want to use the YC output over the composite and the component over the YC. (careful, if you read to fast you will mix up the terms composite and component.)


The two most popular comb filtesr are 2-d and 3-d. A 3-d filter will also include a 2-d filter. It will perform 3-d on static images and 2-d on motion. In the early days, the 2-d section of a 3-d filter was often lower quality than some outboard 2-d filters. Today, comb filters have pretty much reached their peek. (3-d filters are good, but cannot match native YC.)


Cross-color happens when color infomation ends up in the luma channel. This shows up is little rainbows in fine detail. Dot-crawl shows up when luma information ends up in the chroma channel. This shows up as little teeth along vertical and horizontal edges. It is easy to see these on network TV logos if you go to your local goodguys store.


It is easy to remove dot-crawl and most current 2-d filters do this. Cross-color is much more difficult to remove. Only a 3-d filter will remove it and this is only on static images. Faroudja has a simliar technology that is in their processors. (including the sage chip.)
 

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You're absolutely right, but we're talking about a laserdisc player :) . LD stores video in composite mode, which means the player needs to jump through hoops to separate the luma and chroma signals.


[Yeah, OK, cue squeaky rocking chair, but there are many old discs in my collection that are unlikely ever to pop up on DVD, so I'll be keeping my LD player for a long while yet.]


Actually, sspears, to be perfectly accurate, a 3D filter will perform 3D filtering on any parts of the image that are static across frames, and will drop back to 2D on those pixels where it can't match the luma component with the previous frame. This is why the moving fresnel in the S&N zone plate looks so much better with a 3D filter - the fresnel moves slowly enough that significant areas of it don't change luma from the previous frame.


3D filtering is also known as a 'motion-adaptive' or 'generalised-adapting' filtering technique. It works well on NTSC material, but PAL chroma decoding is very different (and superior in many ways). The BBC did a bit of work on various PAL chroma filtering techniques, and their definitve report concluded that 2D filters could actually be better than 3D for PAL composite video. I don't think it's a co-incidence that no PAL consumer-level product has ever carried a 3D Y/C filter. So it's tough-luck for those of us who want to view NTSC stuff, where 3D filters really shine :( .


I should point out that all my info comes from poking around on the net. If a professional wants to correct any glaring errors, please feel free.
 

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Discussion Starter · #12 ·
I got the new Panasonic TV and the picture is amazing from my LD player. Im running the LD player through S-video and the TV reduces the noise and uses its own comb filter. I tried running the comb filter from the player but the picture didn't look as fresh and as bold as the TV's filter. Austin Powers is great on the TV.
 

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If you want to compare the comb filter in the TV to the one in your LD player, compare the picture you get when hooking it up with S-video (which uses the comb filter in your player) to that you get when they're connected using a composite connection (which will cause the comb filter in your TV to kick in). Make sure the cables are the same quality.


Your TV will probably have other filters affecting the player, though I prefer a little noise to the 'processed' look most filters cause.
 

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Quote:
running the LD player through S-video and the TV reduces the noise and uses its own comb filter.
If you are using the S-Video out of your LD player, then you are NOT using the comb filter in your TV. That is bypassed with S-Video. Instead, you are using the comb filter in your LD player.
 
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