1. This site uses cookies. By continuing to use this site, you are agreeing to our use of cookies. Learn More.

DVI Capacity - 1080p or not?

Discussion in 'Video Scalers & Video Processing' started by cmcg55, Dec 29, 2005.

  1. cmcg55

    cmcg55 Member

    Joined:
    Jun 5, 2005
    Messages:
    306
    Trophy Points:
    16
    Ratings:
    +0
    Title says it all I think. Read something the other day suggesting DVI capacity was the same as HDMI capacity, which I didn't think was the case, and that DVI can indeed handle 1080p (which I had previously heard from someone who may or may not have been talking out their derriere, was not the case).

    Anyone know the official word?
  2. StooMonster

    StooMonster Member

    Joined:
    Nov 20, 2002
    Messages:
    4,936
    Trophy Points:
    106
    Ratings:
    +299
    DVI can handle 1920x1200 @ 60Hz, which is higher bandwidth than 1920x1080 @ 60Hz required for 1080p HD. (Proper term is single-link DVI.)

    DVI-D (dual-link DVI) can support 3840 x 2400 @ 60Hz.

    Most common use of dual-link DVI atm is Apple 30" Cinema Display which is 2560x1600 pixels (and is gorgeous).

    HDMI has maximum pixel clock of 165MHz, which is pretty similar to single-link DVI.

    StooMonster
  3. cmcg55

    cmcg55 Member

    Joined:
    Jun 5, 2005
    Messages:
    306
    Trophy Points:
    16
    Ratings:
    +0
    Thanks. Would have been rather surprised otherwise given most of the video processors on the market right now utilise DVI rather than HDMI. While I understand DVI being an older technology, given the role of video processors is obviously confined to a distinct area of AV, if they were using an inadequate technology (insofar as no 1080p throughput), I'd be surprised any were being sold at all.
  4. StooMonster

    StooMonster Member

    Joined:
    Nov 20, 2002
    Messages:
    4,936
    Trophy Points:
    106
    Ratings:
    +299
    DVI is an older connector, not an older technology per se. The technology is the same as HDMI ... that's why you can buy convertor plugs from DVI>HDMI and HDMI>DVI; but DVI is slightly more limited than HDMI, in that it can only carry RGB not YUV colourspace.

    There's been a couple of posts recently about two new (competing) formats to replace HDMI connectors next year: one from Silicon Image and friends (who brought you DVI and HDMI); and one from VESA (who brought you screen timings).

    StooMonster
  5. philgreeen

    philgreeen Member

    Joined:
    Jan 2, 2005
    Messages:
    50
    Trophy Points:
    6
    Ratings:
    +0

    Stoo, doesn't this imply that the scalers like LumagenHDPPro with DVI-D output are somewhat 'more' future proof than those with only DVI-I output ?

    I've seen a lot of forums discussing the pros and cons of difference devices and this struck me as quite important given the expected leaps in screen resolution in the future.....?
  6. StooMonster

    StooMonster Member

    Joined:
    Nov 20, 2002
    Messages:
    4,936
    Trophy Points:
    106
    Ratings:
    +299
    Sorry, my post above is confusing... just because it's DVI-D doesn't mean it's dual-link capable: DVI has some stupid naming conventions.
    DVI-I means connector/cable carries digital and analogue signal
    DVI-A means connector/cable carries analogue signal only
    DVI-D means connector/cable carries digital signal only

    Then DVI-I and DVI-D are both available in single-link and dual-link versions. Dual-link HDMI is specified, but I haven't seen any implementations yet.

    Would be fantastic if Lumagen Pro HDP supported dual-link DVI-D, I don't know if it does perhaps Gordon could confirm?

    Supporting dual-link is relatively simple, and only a matter of a second TMDS Transmitter chip on the DVI output. I expect we'll see scalers supporting this, if they support higher resolutions than 1920x1080, in 2006 or beyond.

    Although supporting higher resolutions isn't simply limited to digital signal bandwidth, the scaler's processors have to have enough grunt to support scaling to higher resolutions too.

    StooMonster
  7. Dale Adams

    Dale Adams Member

    Joined:
    Jul 9, 2003
    Messages:
    175
    Trophy Points:
    18
    Ratings:
    +15
    A few more clarifications:

    1) Dual-link DVI won't support 3840x2400. That would be 4x the bandwidth of a single DVI link (as you've doubled both dimensions, not just one), not the 2x you get with a dual-link connection.

    2) I'm not aware of any video processor which provides a dual-link DVI output. This includes products from Lumagen, DVDO, etc. . .

    3) The only dual-link products I've seen have been a very few video cards for PCs.

    - Dale Adams
  8. StooMonster

    StooMonster Member

    Joined:
    Nov 20, 2002
    Messages:
    4,936
    Trophy Points:
    106
    Ratings:
    +299
    Thanks for the clarifications Dale, your first point made me think. I got the 3840x2400 from Google searches ... so I thought I would check, seeing that that one cannot believe everything one reads on the net!

    So went to Silicon Image's website and TMDS Receivers and Transmitters top out at 165MHz for single-link DVI and 330MHz for dual-link DVI.

    Silicon Image list maximum resolution of pair of SiI 163B Dual Link DVI Receivers as "UQXGA" resolution. Sounds like they mean QUXGA = 3200×2400 (WQUXGA = 3840×2400). However, as you point out this is twice single-link's bandwidth! So, simple check of specs of IBM T221 LCD monitor (WQUXGA resolution) finds that at 60Hz it's driven by either two dual-link or four single-link DVI connectors. Interestingly, you can drive WQUXGA with single-link DVI, but only at 12MHz! http://www.theinquirer.net/?article=8578

    So, after all this, Apple's 30" 2560x1600 @60Hz LCD is near the theoretical limits of dual-link DVI. :)

    Dale's right, there are not many dual-link implementations at the moment: screens from Apple (and Dell in 2006), ATi's FireGL workstation cards, nVidia's Quadro workstation cards, Gefen dual-link DVI switcher (that doesn't work properly in my experience), Apple PowerBook and Apple graphics cards, nVidia GeForce 7800 GTX 512MB card, and entire range of ATi X1K cards (even the cheap X1300). However, we may start to see more dual-link DVI monitors from broad range of manufacturers during 2006.

    StooMonster
  9. Welwynnick

    Welwynnick Active Member

    Joined:
    Mar 16, 2005
    Messages:
    6,921
    Trophy Points:
    133
    Ratings:
    +797
    I think many people didn't realise that the data capacity of HDMI, while entirely adequate, was essentially no more than DVI, in video terms. HDMI does, of course, support high resolution multi-chnnels audio, and may carry 10 bit component video, as opposed to 8-bit only with DVI.

    What you never hear people talking about , though, is dual link HDMI. This mirrors dual link DVI interfaces, but has a larger connector, rather than just a fully populated one. Single link HDMI is connector A, and dual link is connector B. Never heard of anyone using one, though.

    Nick

Share This Page