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Where video signals over DVI are decoded?

Discussion in 'Playback Devices' started by Octavio, Oct 27, 2004.

  1. Octavio

    Octavio Stunt Coordinator

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    Maybe this thing was already covered, but

    Does somebody know where decoding of digital video data takes place, when a DVI-D connection is being used from DVD to TV?

    Does the TV have an internal DAC or something like that?

    If so, should I compare the quality of that "TV DAC" with the video DAC's of my DVD player to decide if to go digital (through DVI) or analog (through component) from DVD to TV?

    In other words, is it possible, that depending on the quality of DAC's, PQ be better under an analog (component) connection than under a digital (DVI/HDMI) connection?

    Thanks for your help

    Octavio
     
  2. John Garcia

    John Garcia Executive Producer

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    DVI is digital all the way to the TV.

    DVI theoretically should yeild a better picture, but in the two cases I've seen it in use, it was worse or the same as component.
     
  3. SimiA

    SimiA Second Unit

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    I agree with John on this one. I see no significant difference beteween the two.
    If you want the ability to archive the material you're watching in the future, go with DVI.
    Vb
     
  4. Stephen Tu

    Stephen Tu Screenwriter

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    DAC quality is unlikely to make any difference. Scaling quality might, on a fixed pixel display (non-CRT).

    DVI has absolutely no relationship to the ability to archive material.
     
  5. SimiA

    SimiA Second Unit

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    Stephen, you're correct. I should have mentioned that it may be an issue where DVI/HDCP is concerned, and copy protection flags may be engaged if you wish to archive HD material.
    Vb
     
  6. Stephen Tu

    Stephen Tu Screenwriter

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    DVI has nothing to do with archival. Regardless of presence of HDCP encryption, the data rate of DVI is far too high for practical storage on hardware of the present or near future. Even when hardware eventually catches up, it still wouldn't be logical to shuttle around and store uncompressed data when compressed data is available.

    Transport of data for archival purposes will remain on IEEE1394, aka firewire, not DVI / HDMI, for the forseeable future. There are copy protection standards on both types of interface.
     
  7. Octavio

    Octavio Stunt Coordinator

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    I want to go back to my original question:

    How digital video data, coming from a DVD through a DVI connection, gets converted into actual images in the HDTV screen? Is there some kind of DAC, or the signal never gets analog?

    What can cause that PQ be better under an analog (component) connection than under a digital (2 meter single link DVI-D) connection if a high scan 1080i CRT monitor (like my Sony KV-30XBR910) is being used. Here no downconversion is needed.

    Octavio
     
  8. ChristopherDAC

    ChristopherDAC Producer

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    Okay. Most modern TVs, particularly widescreen ID and HD models, digitise all inputs and then perform a series of mathematical manipulations on the signal to do colour decoding and balance, sometimes resolution scaling, contrast and other picture functions, and all the rest. the output from the onboard video processor is then converted to an analog voltage signal to drive the CRT guns or plasma, or retained in digital format and bussed to the LCD or DLP transistor network [where it undergoes a conversion to a completely different kind of voltage signal to drive those devices]. So if you are using component video inputs, the chances are very good that the same DACs are driving the picture tube as if you used DVI. As for picture quality... YMMV.
     

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