What causes massive brightness variations during analog video capture?

Discussion in 'Computers' started by John_Berger, Sep 28, 2003.

  1. John_Berger

    John_Berger Cinematographer

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    I'm currently converting my five-video Danger Mouse series to DVD-R. The first tape that I converted required no fudging of the capture setting. The second tape was unbearably bright where I have to reduce not only the brightness but the contract as well to get the glare down to an acceptable level. Of course, this resulted in muted colors. The third tape required brightness reduction, but colors were not affected. It looks fine with the reduced brightness, just like the first tape without brightness.

    What's wierd is that on the second tape, the brightness is only a factor once the cartoons start. The HBO Video intro is fine as is the Thames Video intro. Once the cartoons start -- the brightness is overpowering.

    This is not the first time I've run into this either. I also ran into it when converting my daughter's numerous Blue's Clues tapes to DVD-R where some tapes required no adjustment, some tapes requires brightness adjustment, and some tapes could not have the same quality no matter how I adjusted the contrast and brightness.

    Macrovision is not an issue. I'll just leave it at that.

    What causes this problem? Has anyone else run into this?
     
  2. Glenn Overholt

    Glenn Overholt Producer

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    I think that it would be just a different recording process. Different equipment or even different engineers. Can I throw in that some of your tapes may be more worn out than others?

    Jut guessing - Glenn
     
  3. John_Berger

    John_Berger Cinematographer

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    I guess anything's possible, but none of them should be any more worn out than the others. I try to keep my tapes in good condition. If it was wear, however, the opening HBO and Thames logos should have been affected as well. Also, there are no brightness issues on the TV display itself. All of them have the same video quality during acutal viewing, which also is confusing the hell out of me.
     
  4. Dave Poehlman

    Dave Poehlman Producer

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    Are these commercial tapes? Could it be the Macrovision (skirting forum rules here)?

    If not, here are a few shots in the dark:

    Try a different VCR as the source if you can. Also, check the VCR's settings. Perhaps there's some sort of auto-tracking or noise reduction that is wreaking havoc with your DVD recorder.

    P.S. I love Danger Mouse.
     
  5. John_Berger

    John_Berger Cinematographer

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    This is actually over a AV/DV bridge which has technology built into it that prevents capture if the Macrovision signal is detected, hence why I said that Macrovision isn't a problem.

    This also happened when converting my daughter's Blue's Clue's tapes which was done using a different VCR, so this isn't restricted to just one VCR unit - some tapes were fine, some were intensely bright but only on the capture unit, not the TV, and it lasts throughout the duration of the tape. Very wierd.
     
  6. Dave Poehlman

    Dave Poehlman Producer

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  7. Ken Chan

    Ken Chan Producer

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    Bad analog video cable?
    Bad DV codec in converter?
    Defective converter?

    I haven't seen this using an ADVC-100, but I've never tried cartoons.

    //Ken
     
  8. John_Berger

    John_Berger Cinematographer

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    I would think that if it's any of those three, the problem would be consistent for everything, but it's not. I even put in the first tape (which had no problems) during the same application session and it cam across fine. Kicked that out, put the ultra-bright tape in and it was still ultra-bright. It's as though the signal for that tape is just skewed, but then why doesn't it show up that way on the TV?
     
  9. Ken Chan

    Ken Chan Producer

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    If there's a bug in the codec, it could be only for some edge case that is seen only with particular kinds of video. It's a remote possibility, but it is possible in the broad sense. There is some cause for what you're seeing....

    Since you've tried different VCRs, the obvious next step is to try a different converter (same model or not).

    Another thought: what does Macrovision look like through the converter? Maybe something in those tapes is triggering that protection.

    //Ken
     
  10. John_Berger

    John_Berger Cinematographer

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  11. Patrick Sun

    Patrick Sun Moderator
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    Are you certain this device detects ALL forms of Macrovision? I know of at least 2 types of Macrovision, perhaps your device doesn't know what to do with the Macrovision embedded on these old tapes. Plus, in my experience, HBO/Orion video tapes did exhibit the presence of Macrovision encoding.

    If this is the case, chalk it up to copyright protection, and move on to something else because members should be aware that circumventing forms of copy-protection is not a topic we tolerate here.
     
  12. John_Berger

    John_Berger Cinematographer

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    Steady on, Penfold ... er ... Patrick. [​IMG] Trust me. Macrovision is not an issue. I'll say no more on that subject.

    However, even if it was an issue, that doesn't explain why the video intros are fine. My experience with Macrovision tapes is that the whole thing is protected - intros, traliers, etc - not just the movie itself.

    It also doesn't explain and why different tapes are affected while others are not if all of them are Macrovision encoded.

    I should set up a system with my old capture card and see if the same thing happens with the same tapes. Hmmm....
     
  13. Ken Chan

    Ken Chan Producer

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    I'm not saying that the tapes actually are Macrovision-encoded, but that the converter is somehow incorrectly thinking that some passages on some tapes are. On VCRs, a symptom would be screwed up brightness/contrast. When you said that it "prevents capture", it wasn't clear if it literally prevents capturing anything, or if it prevented capturing correctly, or what.

    But now that that's settled, I'm out of ideas.

    //Ken
     

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