Hdmi

Discussion in 'Displays' started by Brad Wood, Nov 4, 2004.

  1. Brad Wood

    Brad Wood Stunt Coordinator

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    Well, wifey has finally given the green light for basement HT. All I had to do was agree to do all the laundry and wash all the dishes for six months, but that's another thread altogther.

    Anyway, I'm trying to hit it fast before she changes her mind and I'm furiously designing a lighting scheme, paint colors, AC layout, acoustic treatment etc. I'm either going with the AE700 or the Z3 for my projector and I'm curious on anyone's experiences with HDMI. I'm an AV designer and I work primarily in schools and boardrooms so I usually stay away from DVI. Most of my clients don't need it and it's usually more headache than it's worth. I'm wondering if HDMI is worth it to run right now. How far can I run HDMI? Is it a different protocol than DVI or basically DVI connectorized differently? Will I really see that much of an improvement over analog component video?

    I'd just like to hear from anyone who has run it and their general feelings about it. I may just put a 3" PVC tube in between my rack and the ceiling projector location so I can pull it later, but if it's worth it, I'll run it now. Thanks!
     
  2. David_Rivshin

    David_Rivshin Second Unit

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    I haven't personally used an HDMI connection yet, but I feel pretty safe in saying that you definitely want to use the HDMI input rather than component. Since the AE700 and Z3 are both LCD projectors, any input must be converted to a 720p digital frame before it's displayed. IOW, if you were to use any analog input the projector would need to digitize it first. So you end up with the DVD player converting the digital image to an analog signal, and the projector doing the reverse, and resulting in a generational loss.

    HDMI is basically DVI on a smaller connector. Also HDMI has some pins for carrying digital audio, but that's not too important for a projector. DVI has some pins for carrying analog video (basically a VGA signal), which HDMI does not have. That's mainly useful for PC video cards which can have one connector for either an analog of digital display. HDMI can theoretically run farther than DVI. You can get DVI /HDMI adapters if you have an HDMI/DVI mix, but I believe you lose some of the distance benefits that way. HomeTheaterHiFi actually just had an article discussing DVI and HDMI, which you might find useful.

    So the long and short of it is, if I were to get one of those projectors I would definitely get an upscaling DVD player with HDMI output, and run an HDMI cable. I wouldn't think twice about it. Only reason not to is if you're tight for cash and can't afford to get a new DVD player immediately.

    Of course since those projectors only have one HDMI input, you might have a problem if you have more than one digital source (say also a (high-def) satellite receiver). In that case you'd have to make a judgement call as to which you want to have the best quality. Or get some kind of a switcher; some receivers can switch HDMI today, but very few.

    Hope this helps,
    -- Dave
     
  3. John S

    John S Producer

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    Interesting David...

    Do all displays that have HDMI input support the analog PC DVI signals? I actually didn't know this about HDMI.
     
  4. David_Rivshin

    David_Rivshin Second Unit

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    I assume you meant DVI? HDMI can't carry any analog signals, but DVI has the option. There are 3 flavours of DVI connection:
    DVI-D: digital signal (same as HDMI, adapters are available)
    DVI-A: analog signal (same as VGA, adapters are available)
    DVI-I: both DVI-D and DVI-A together

    Most consumer equipment only has DVI-D connectors, and it's impossible to plug a DVI-A or DVI-I cable into them. Most PC video cards have a DVI-I output, so they offer alot of flexibility as far as the display you use. The benefit of having such a universal connector is that the space on standard bracket is very limited, so having both a DVI and VGA connector for each of 2 supported monitor would simply not fit.
    HDMI dropped the analog support, I presume because they figured people would use component or VGA if they wanted the analog. It's also harder to carry an analog signal over great distances (with good quality) than digital.
    I expect PC video cards to continue using DVI for awhile, whereas consumer electronics will probably completely switch to HDMI within the next year.

    -- Dave
     
  5. John S

    John S Producer

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    Ok. I actually just misread the previous post....

    DVI-I, sounds very versatile.....
     

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