DVE Calabration last night, I think my video signal is being "Clipped"

Discussion in 'Displays' started by Chris Brock, Oct 7, 2004.

  1. Chris Brock

    Chris Brock Second Unit

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    Ok, I finally got a copy of DVE last night and let me first say it is awesome. There was obviously allot of time and effort put into it. I am not exactly sure if this is going to be the proper forum for this but it seemed to make the most sense to me, now on to my concern............

    According to the narrator during the brightness adjustment portion the background that is used to adjust the brightness has three vertical bars on each side, one at below the level of black, 1 at 2% greater then black and another at 4%. It stated that if you cannot see the bar that is below the black level then that means that somewhere in the video signal that portion of information is being clipped. I could not see the bars that were below black level no matter hose bright I made it. I am currently running from a Yamaha DV-S5650 DVD player (http://www.yamaha.com/yec/customer/m.../DV-S5650_e%20(U).pdf ) to a Yamaha HTR-5760 receiver (http://www.yamaha.com/yec/customer/manuals/HTR_5760.PDF ). From there is goes to a Mitsu 55” HD RPTV and all connections are component vidoe. I am not sure what piece of equipment is causing a problem or if it really even matters at all. I was just curious if it is something that I should be concerned about or not? Thanks for any advice!!
     
  2. Richard_B

    Richard_B Stunt Coordinator

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    I don't really have an answer with much help but....

    I run a Yamaha DVD player (different model) and all three bars do show up. One of my good friends runs a 55" Mitsubishi HDTV and he also gets the three bars.

    It might be a good idea to check into your warrenty and possibly have the TV looked at. I am not even sure if not seeing the below black bar is a real issue or not.

    Question, is the brightness test the only test you were not able to complete? Did you get the color, tint and the rest of the settings down and then go back to try the 3 black bar test?
     
  3. ChrisWiggles

    ChrisWiggles Producer

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    Blacker than black data is very often not preserved by the DVD player. It is not related to your TV if you can turn up the brightness such that the black is visible gray but only see two bars. This shows you that data below reference black is not being preserved somewhere in your playback/processing(if applicable)/etc video chain.

    It is ideal to preserve the full range of digital values encoded on the disc, but for a variety of reasons (involving lots of technical confusion, sometimes design incompetence, etc), that material is not preserved.

    Sometimes, a DVD player will preserve BTB data in some modes but not others. You might explore changing the black level setup option, if it is available in your DVD player, between 0 and 7.5 IRE output. You will have to recalibrate after the change, but you may find that one setting will preserve BTB data, but not the other. If both clip black, then if this is a sufficient concern for you, then you'll need to find a new source that does not do this.

    As for setting black levels without the BTB bars, you should set it with this pattern so the background is as black as possible, but the two bars which are above reference black(digital 16) are still visible.
     
  4. Chris Brock

    Chris Brock Second Unit

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    hmmm, i dont know that it is that huge of a deal to me, more just a surprise then anything. I would not have guessed that would have happend. it doesnt really bother me that much so i can definitly live with it. Thanks for the explanation!!
     

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