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Digital Video

Discussion in 'Projectors, Screens & Video Processors' started by IanW, Nov 12, 2002.

  1. IanW

    IanW
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    A little question for the well informed of you out there. . . . .

    As Audio is moving down the digital path (has been for ages actually) with transfering digital sound around for as long as possible before it gets converted to analogue, when will video go the same way, or can it already?

    To ellaborate, Meridian can take a digital audio signal from a CD or DVD player and pass it uncompressed and unconverted into a digital processor/preamp, this then gets passed uncompressed and unconverted into its digital speakers that then perform the DAC just before the speaker. Can this be done with a video signal? One would assume that when viewing a PC monitor this is a true digital image?

    Your wisdom please.

    Ian.
     
  2. kevenh

    kevenh
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    Generally, we could have had digital video in the home, but Hollywood said "NO".
    They're worried about people making perfect copies...

    But. as you can see elsewhere on this forum, it is possible to buy a DVD player with digital video. (look for "SDI player at £370" or similar posts)

    Also, SACD (and DVD-A?) only have analogue outputs for a similar reason.
     
  3. Chris Muriel

    Chris Muriel
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    "Generally, we could have had digital video in the home, but Hollywood said "NO".
    They're worried about people making perfect copies"

    Sure are !
    That's why HDCP is incorporated within ICs from my employer (Analog Devices) & competitors (e.g. Silicon Image).

    Another useless acronym : HDCP = High-bandwidth Digital Copy Protection

    Chris Muriel, Manchester
     
  4. MarkTaylor

    MarkTaylor
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    Hmm... thought it was High-bandwidth Digital Content Protection ?

    Mark
     
  5. AV Junky

    AV Junky
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    Don't know if this counts as wisdom, but here's my two-pennies-worth :D

    Yes, digital video signal transfer is perfectly possible. As has already been said, would need a DVD player with DVI (as I like to call it) out. Then would need a display device with the same connector. Some of the more recent models of projector have this (Panasonic PTAE300 is one from memory, though are several others), and I think I remember reading that there are a small number of plasmas with it too.

    As far as PC monitors are concerned, the signal from the graphics card to the monitor is actually analogue (RGBHV). It then undergoes A-D conversion in the monitor. Bit silly of course, as the signal started off as digital in the PC in the first place! Hence the slow introduction of DVI for users who want higher quality video displays. At the moment, DVI is only fitted to more expensive TFT monitors. DVI graphics cards are actually quite cheap these days (saw one for less than £40 a few days ago).
     
  6. AV Junky

    AV Junky
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    True, but also because current digital audio connections (coaxial and optical) are not high enough bandwidth for full multi-channel audio. However, digital audio transfer for multi-channel music is starting to happen. If I remember rightly, it was Denon who released the first DVD & receiver combination containing a proprietory full digital audio link. This had to go through an approval process first to prove to keep the music publishers etc. happy.

    Have also read that in the near future it will be common to see players and receivers fitted with Fire-Wire type connections to allow full multi-channel digital audio transfer.
     
  7. ReTrO

    ReTrO
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    Standard PC monitors (CRT types) need an anlogue feed at the end because they are analogue display devices. There are a few that DVi inputs about, but they are pretty rare as it's not really needed.

    If you're looking at LCD's or PDP's then best to get one with Dvi really.
     
  8. AV Junky

    AV Junky
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    OK, I thought someone would have to make a comment about this! :rolleyes:

    Yes, fair enough, CRT monitors are analogue display devices.

    Suppose that in this case it would be more accurate to say that some authorities would argue that maintaining the video signal in the digital domain until shortly before it's passed to the CRT guns would improve picture quality by minimising the possibility of interference (which the analogue signal would be more susceptible to). Does this make any real difference in a standard situation where you've got 1-2m of VGA cable running from base unit to monitor? Probably not, as ReTrO has stated. Might be more of a consideration if longer runs were involved, with high quality demand at the other end.

    As ReTrO has said, the greatest potential benefit would be with digital display devices such LCD and plasma. In this situation, the possibility of direct pixel-to-pixel control and avoidance of D-A-D conversions is what gets the large display enthusiasts all excited ;)
     

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