S-Video vs. Composite + Wega DRC

Discussion in 'Archived Threads 2001-2004' started by RichMiller, Jun 8, 2001.

  1. RichMiller

    RichMiller Extra

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    Been running 100% S-Video in my HT (sources are primarily TiVo and DVD, which both output S-Video natively) since I first figured out which cable was which. I could definitely see the difference between S-Vid and composite, even on my old 27" TV.
    I upgraded to a non-XBR Wega a few months ago, and have been really enjoying everything about it, but I noticed immediately that in scenes with a lot of horizontal motion I was getting some 'combing' effects (similar to 3:2 pulldown's effect from DVD) as the two fields of the interlaced NTSC image struggled to be coherent together. This is a subtle effect, and is only really noticeable on medium-slow movement; quick motion is blurry anyway, and super-slow movement appears to give my brain ample time to resolve the interlacing.
    It occurred to me today that by using S-Video I'm bypassing the Wega's vaunted Digital Reality Creation comb-filter, and on thinking back, when viewing the Wega's straight RF-in interpretation of my live cable signal (which I don't usually do, preferring to timeshift via TiVo), I don't remember seeing the comb effect.
    I can't test this sitting at my PC here, but does anyone know whether using my Radio Shack S-Video-to-composite adapter on the S-Vid feed from my receiver, and then letting the Wega's DRC do its magic on the resulting composite signal has any chance of improving my image? I can test this tonight, but I was wondering if anyone had followed this mad path of logic in the past. [​IMG]
    -Rich
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    Technophilia is like hemophilia...
    In both cases bleeding oneself dry is a danger.
     
  2. RANDY FISHER

    RANDY FISHER Second Unit

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    DRC is only available on the HD ready Wega's. The XBR's and (2) of the new KV series this year. DRC is the sets internal line doubler/video processor. You must be referring to the sets color comb filter which would be by passed by using s-video or component video inputs if so equipped.
    Randy
     
  3. Jim A. Banville

    Jim A. Banville Supporting Actor

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    The only time you bypass DRC is by using either 480p or 1080i input signal. Composite and S-video only carry 480i. You should really try to use component cables between your DVD player and TV.
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    Jim
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    Mancow rocks! www.mancow.com
     
  4. RichMiller

    RichMiller Extra

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    Ah. I obviously took in some bad info at some point; I was certain that DRC was just the comb filter.
    In any event I tried the composite-through-comb-filter thing over my lunch break, and quality dropped hugely, so whatever is being done in the comb-filter in my KV-36FS12 is inferior to good old-fashioned S-Video. :)
    Case closed.
    -Rich
     
  5. RyanDinan

    RyanDinan Stunt Coordinator

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    Well, since DVD is stored as component video, moving down to S simply lowers color resolution, and does not combine it with the luminance (composite) - It keeps the Y and C separate from the start.
    Therefore, it's smart to run S to your TV from a DVD player, if your TV doesnt have component inputs. This bypasses the comb filter in your TV, as it does not need to separate the color and black&white info like it would need to do with composite. That's why its bad to use composite - The video starts out with the color separated, then gets combined to be sent to the TV, only to be separated again...Avoid composite at all costs! [​IMG]
    Now, laserdisc is different. Video is stored as a COMPOSITE signal. Any laserdisc player with S-video output has an internal combfilter to separate the Y/C and send it out as S-video. This comb filter in almost all laserdisc players is probably much worse than the one in the Wega, so you would want to use the Wega's instead. This is done by using a composite cable from the LD to the TV. The TV will use it's digital 3 line or 3-D comb filter, and do a better job separating the Y/C.
    DRC is an adaptive line-doubling scheme used by HD ready sets. It takes any 480i signal, and outputs it as 960i or 480p.
    -Ryan
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    [​IMG]
     
  6. Allan Jayne

    Allan Jayne Cinematographer

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    The symptoms described appear to be less than perfect de-interlacing (doubling) done by the DRC.
    Really you would want to borrow a progressive scan DVD player (one that properly assembles frames based on the 3-2 pulldown cadence), and try both the progressive and S-video outputs of that player into the TV. Use a movie DVD. This way you can compare the quality of the doubling in the DRC against something else.
    Alternatively if you can borrow an iScan unit, play your existing DVD player S-video into it and also directly into your TV for comparison.
    I can't say that borrowing would be easy but borrowing is better than buying and then finding that the improvement in quality over what your DRC has is miniscule.
    More on line doublers: http://members.aol.com/ajaynejr/video.htm
     
  7. Mike E W

    Mike E W Agent

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    Actually something similar came up over on AVS forum and in the end no one was sure if the DRC is off in progressive or not. This would include some of the experts. One telling thing is that the DRC tends to wipe out the chroma bug yet you will see no difference if you switch from progressive to interlaced on the Wega even when getting a progressive signal from a progressive player. Not in any combination, player interlaced/TV progressive, etc. This is something I have looked at myself since I have a SD9200 hooked up to a XBR400 and I have to admit it appears true. It would be interesting to learn what the deal is with the DRC and how it works, I have read that it doesnt work in the same fashion as a more typical line doubler. Anyone shed some more light on that?
     
  8. RANDY FISHER

    RANDY FISHER Second Unit

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    Mike...I know this is getting off the topic but I have read some of what you are talking about over at the AVS. I too have looked at a progressive player (Sony 700p) on my XBR400 and could see no sign of the chroma bug in progressive mode even though that player is supposed to exibit it. My 7700 (interlaced) does not show the bug on the XBR but sure did on my 50" RPTV I got rid of. I do know if you play a progressive player on the XBR the DRC functions on the pic mode menu's are greyed out but I wonder if it is really "off" all together?
    Randy
     

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