DVI output to Philips TV HDMI In?

Discussion in 'Mac Accessories' started by Makosuke, Jun 7, 2006.

  1. Makosuke macrumors 603

    Joined:
    Aug 15, 2001
    Location:
    The Cool Part of CA, USA
    #1
    Got me a budget 30" widescreen Philips LCD TV a few months back, and I'm generally quite happy with it. It has inputs for VGA, HDMI, and a bunch of other stuff, and a sllightly odd (for TV) resolution of 1280 x 768.

    I can drive it off of my tower using a VGA cable and get a pretty good picture after some fiddling around with the settings. But I'm wondering if there's any way to get it working with a digital signal through the HDMI input.

    I went and bought a budget DVI-HDMI cable, but I get no signal when I plug the two together with it--the Mac doesn't see the monitor, and the monitor gets no signal.

    Maybe this is to be expected, and the formats aren't as compatible as they seem, or maybe I'm just not setting the Mac up correctly--I have no idea, and I failed to find much in searching about the issue online. Could be that the TV is expecting a 1080i or 720p signal in and won't recognize anything else, but my Mac isn't outputting that, could be something else.

    Is there something obvious I'm missing here, or is this just not going to happen?
     
  2. patrick0brien macrumors 68040

    patrick0brien

    Joined:
    Oct 24, 2002
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    #2
    -Makosuke

    Hmm, this is a bit perplexing. HDMI and DVI are identical in Video signal, so even referring to them as 'compatible' is an understatement. The only real difference is that HDMI adds 7.1 audio to the cable bundle - and, of course the plug is physically different.

    Silly question: Is the TV's HDMI port even enabled? That would explain both ends of the issue.
     
  3. Makosuke thread starter macrumors 603

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    Aug 15, 2001
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    The Cool Part of CA, USA
    #3
    That's what I'd read, so I was a little surprised when it didn't work. Yes, the HDMI input is enabled and working--my DVD player is plugged into it, and it works fine. The only thing I can think of is that the Mac isn't recognizing the display, and so isn't outputting any signal to it--does HDMI carry display information back the other way like DVI? Don't remember that from the spec...

    To clarify one thing, the TV (according to the borderline useless manual) only expects a "PC" input on the VGA port--the HDMI is expected to be only for a Hi-Def TV signal. As such, I would assume it only supports 480p, 720p, or 1080i (might also be able to downsample 1080p, I don't remember offhand), so perhaps there's a disconnect on the Mac end somewhere due to this?

    Could also be a bum cable, of course, which is harder to check without buying a new one. I could test the pins for continuity, I suppose..
     
  4. patrick0brien macrumors 68040

    patrick0brien

    Joined:
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    #4
    -Makosuke

    Ok, it could be a lot of different things - cable included.

    1) I'd try to force-set the Mac's display to native on the monitor - to compensate for lack of feedback to the computer.
    1a) Try 480, 720, 1080, etc.

    2) Have you tried a DVI-DVI cable with an HDMI adapter? I've heard that, and its more expensive sibling HDMI-HDMI with DVI adapter works. I cannot speak to a DVI-HDMI cable.

    note: I know it's hard to force a resolution when you cannot see it :p , and one cannot force it to a resolution using a different monitor, give me a second and I'll see if I can write a quick Applescript that you can use on Login to force the resolution...
     
  5. patrick0brien macrumors 68040

    patrick0brien

    Joined:
    Oct 24, 2002
    Location:
    The West Loop
    #5
    Ok, that scripting came up a big fat nothing. Here are a few more options:

    http://www.3dexpress.de/

    or, if you have another computer, get a VNC server on the machine you wish to drive the TV and a VNC viewer on the other machine. Both of these are available on Versiontracker.com. VNC to the TV'd machine and force the resolution there.
     
  6. Makosuke thread starter macrumors 603

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    Aug 15, 2001
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    The Cool Part of CA, USA
    #6
    Thanks for the suggestions. I'd run across that DisplayConfig program a little while ago and somewhere in the back of my mind thought it might be the solution to my problem.

    Just walked over to test... and remembered that I'd just given my ADC-DVI adapter to my dad for a new monitor he got! So now I have functionally one DVI out but no adapter for anything but VGA out of the ADC port, and my main monitor is of course a newer cinema display with DVI only.

    Hmm... Maybe I can hook the TV up via both VGA and DVI, and try to use the VGA connection to configure the DVI output, then switch TV modes to check. Either that, or set it blind, plug it in, and hope for the best, but I hate doing that.

    Or maybe I'll just ask to borrow my adapter back to test it. Not worth buying another unless it's going to work--I be on a tight budget these days, so it's pretty much work with what I got or do nothin' at all.
     
  7. Makosuke thread starter macrumors 603

    Joined:
    Aug 15, 2001
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    The Cool Part of CA, USA
    #7
    Little follow up here.

    I realized that of course my new MBP has a DVI output, so I tested it using that... and bizarrely, it worked this time. Perhaps something changed in the most recent 10.4 updates, or maybe the mobility X1600 has more features than my 9800 pro, or maybe I was just doing something stupid last time and didn't realize it. OSX even recognized it as "HDMI Out", and offered several interlaced image options in addition to the progressive ones, as well as an Overscan checkbox.

    In any case, if I turn on overscan and set it to a high-ish resolution, it ends up looking pretty good (the downsampling the TV does looks quite good), although of course it "bleeds" over the edges. If I turn off overscan the image isn't centered at all (borders at top and bottom, slid offscreen to the right), but that's mostly my TV not the output (there aren't even any adjustments on the HDMI input!).

    On the down side, Philips didn't intend that input to be driven by a computer, so it doesn't seem to allow an input at the TV's native resolution. I tried DisplayConfigX to see if I could massage the output to something close, but the unpaid version doesn't support resolutions that high, so oh well.

    Just glad I got it working.
     
  8. superbovine macrumors 68030

    superbovine

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    #8

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