27" iMac HDMI-to-Mini DisplayPort limits display to 720p. Pleasefeedback Apple.

Discussion in 'Apple' started by bartbrn, Jul 23, 2010.

  1. bartbrn

    bartbrn Guest

    27" iMac owners or prospective owners, especially those who THOUGHT
    they could use their 27" iMacs, with the proper HDMI-to-Mini
    DisplayPort Converter, as HD (1080p) TVs, PLEASE read this message --
    at least the first three paragraphs -- and if you care about this
    problem, please send feedback to Apple.

    This message is about the existence of, and reason for, the 27" iMac's
    Mini DisplayPort's inability -- AS AN INPUT PORT -- to accept or
    display any resolution on the 27" iMac's display other than 1280p x
    720p (and definitely NOT the 1080p -- aka "HD" -- that the Apple
    Store's description of Belkin's AV360 HDMI-to-Mini DisplayPort
    Converter SAYS it will). This is a known problem to Apple Engineering,
    they KNOW it's the "crippled" EDID protocol at the Mini DisplayPort's
    input, and the fix MAY be as simple as a firmware upgrade.

    The Apple Techs I've spoken with (thank God for AppleCare!) have all
    told me the same thing: get as many people as possible to send Apple
    feedback asking for the Mini DisplayPort to be able to accept, and the
    27" iMac to be able to display, 1080p (or higher) from HDMI device
    signals processed through an HDMI-to-Mini DisplayPort Converter. The
    Apple Techs assure me that Apple takes customer feedback very
    seriously, and if enough people ask for this problem to be fixed --
    the more feedback comments they get on this specific problem -- the
    likelier they are to implement a fix. And it IS a problem: while most
    game console outputs top out at 720p, and for the few consoles capable
    of 1080p, by the very nature of game graphics, 720p doesn't look
    noticeably different from1080p, the same is NOT true of Blu-ray or DTV
    output. At normal computer-display viewing distances of 2 to 4 feet,
    the the image degradation between 1080p and 720p is VERY noticeable.

    The problem and the probable cause:

    I bought my 27" iMac largely on the basis that I'd be able to connect
    HDMI devices to the 27" iMac and get full HD (1080p) on the iMac's
    display, as Apple's 27" iMac advertising, and their description in the
    online Apple Store of Belkin's AV360 HDMI-to-Mini DisplayPort
    Converter, suggests is the case. Apple's description however, leaves
    out one VERY important fact, that is CLEARLY stated on Belkin's web
    page for the AV360 Mini DisplayPort Converter: "Accepts full 1080p
    signal, PROVIDES 720p TO iMAC." According to tested.com, the very
    similar (in function AND $150.00 price tag) Kanex XD, actually OUTPUTS
    1080p to the 27" iMac's Mini DisplayPort, but the Mini DisplayPort's
    EDID implementation allows only 720p to be displayed.

    Putting aside "truth in advertising on Apple Store" arguments for the
    moment, the bottom line is that you CANNOT get full 1080p (let alone
    the 27" iMac's highest display resolution of 2560 x 1440) through the
    Mini DisplayPort. The best you can get, with ANY HDMI to Mini
    DisplayPort adapter, is 1280 x 720, exactly HALF the full resolution.
    It is NOT the fault of the adapter; the fault lies in Apple's
    implementation of the EDID spec. Here's what tested.com says about
    this situation:

    << An iMac can only accept 720p video through the device; while the 27-
    inch iMac's screen supports 2560 x 1440 resolution, it can only
    display half that when using an external video source. Kanex says this
    is because the iMac supports external display identification data
    (EDID) at two resolutions: 720p and its native resolution. Without the
    necessary EDID support, It simply can't accept a 1080p video feed. The
    21-inch iMac's native resolution is good, old-fashioned 1080p, but it
    can't process any video input through the mini DisplayPort.

    << This limitation really puts a damper on the 27-inch iMac as an
    HDTV. Blu-ray Disc players, PlayStation 3 systems, and Xbox 360
    systems can all output at 1080p video. The iMac screen supports well
    over 1080p resolution. The Kanex XD can actually process 1080p video
    through the mini DisplayPort. The bottleneck is on the Mac's side, and
    it's a very strange one to have. >>
    ------------------------------------------------------------------

    The documentation:

    Here's the Apple Store's description of Belkin's AV360 Mini
    DisplayPort Converter, in part:
    ------------------------------------------------------------------
    The Belkin AV360 Mini DisplayPort Converter lets you connect any HDMI
    device such as a PS3, Xbox, or Blu-ray Disc player to the Mini
    DisplayPort on your 27-inch iMac—so you can use the screen to play
    video games or watch movies.

    * Compatible with Xbox, Blu-ray Disc player, DVR
    * Full audio and video support
    * Provides resolutions up to 1080p
    * USB powered
    * Scales resolution to fit the entire iMac (supports 480i, 1080i,
    480p, 720p, 1080p resolutions)

    Mfr. Part No.: F2CD007
    ------------------------------------------------------------------
    BUT, on Belkin's own web page (http://www.belkin.com/
    IWCatProductPage.process?Product_Id=508267) for the AV360 Mini
    DisplayPort Converter (Belkin Part No.: F2CD007), Belkin's description
    clearly states:

    * Accepts full 1080p signal, PROVIDES 720p TO iMAC
    * Delivers stereo audio

    AppleInsider, tested.com (http://www.tested.com/news/kanex-xd-opens-up-
    your-imacs-displayport-to-hdmi-input/426/), and electronista.com
    (http://www.electronista.com/reviews/kanex-xd-for-27-inch-imac.html),
    among others, have reviewed both the Belkin AV 360 and Kanex XD HDMI
    to Mini DisplayPort Converters

    "Full audio and video support," as Apple Store's extremely misleading
    blurb suggests, not only is the iMac display limited to 720p with this
    adapter, the "full audio" turns out to be nothing but standard stereo.

    From Tested.com's review of the Kanex XD:

    "The $150 box serves as a bulky bridge between a home theater device
    like a Blu-ray Disc player or a video game console and the iMac. It
    requires its own power supply, but since you're hooking it up to an
    iMac you can use the power outlet you save by not having a separate
    monitor. Since it converts HDMI signals, it transmits both video and
    audio to the iMac and can pipe out video game and Blu-ray Disc sound
    straight through the iMac's speakers with a single cable.

    "Unfortunately, there's a bizarre hitch, and it doesn't seem to be the
    Kanex XD's fault. An iMac can only accept 720p video through the
    device; while the 27-inch iMac's screen supports 2560 x 1440
    resolution, it can only display half that when using an external video
    source. Kanex says this is because the iMac supports external display
    identification data (EDID) at two resolutions: 720p and its native
    resolution. Without the necessary EDID support, It simply can't accept
    a 1080p video feed. The 21-inch iMac's native resolution is good, old-
    fashioned 1080p, but it can't process any video input through the mini
    DisplayPort.

    "This limitation really puts a damper on the 27-inch iMac as an HDTV.
    Blu-ray Disc players, PlayStation 3 systems, and Xbox 360 systems can
    all output at 1080p video. The iMac screen supports well over 1080p
    resolution. The Kanex XD can actually process 1080p video through the
    mini DisplayPort. The bottleneck is on the Mac's side, and it's a very
    strange one to have.

    This doesn't mean the Kanex XD is useless, though. At 27 inches, even
    720p video looks quite good, even if it isn't as crisp at 1080p video
    and doesn't come close to the displays maximum resolution. Since the
    iMac doesn't play Blu-ray Discs and the Mac video game library is
    still very small, the ability to connect a game console or Blu-ray
    Disc player at any HD resolution is a boon. A $350 Playstation 3 and a
    $150 adapter can give the $1,700 27-inch iMac some much-appreciated
    media flexibility. If you don't have the room for a full home theater
    system, it lets the iMac pull double-duty as a computer and HDTV. It's
    a pricey solution, but so's the 27-inch iMac to begin with."

    CNET's review of the Belkin AV360:

    Belkin AV360 Mini-DisplayPort converter for 27-inch iMac

    June 29, 2010 | 9:31 AM PDT

    The Good: Bridges the gap between 27-inch iMac and HDMI video
    components; simplifies set up by scaling video to match the iMac's
    720p input limit, regardless of source setting; USB-powered, which
    minimizes cable clutter.

    The Bad: Won't input HDMI-equipped PC video to the iMac; no support
    for 2,550x1,440 native iMac resolution.

    The Bottom Line: Belkin's AV360 iMac adapter edges out the competition
    by making it easier to connect HDMI-based video components to your
    iMac's Mini DisplayPort. We'd prefer that Apple had gone with HDMI in
    the iMac to begin with, but until it makes that switch, this is the
    adapter we'd pick.

    electronista's review of the Kanex XD:

    Review: Kanex XD for 27-inch iMac
    Kanex lets iMac owners turn their screen into a TV. (May 8th, 2010)
    The Kanex XD is in theory the dream device for apartment dwellers, or
    just those who don't want to buy a separate TV: it turns the 27-inch
    iMac into a full-fledged TV for anything that works with an HDMI
    input, such as a PlayStation 3 or even your cable set-top box. At
    $150, however, is the feature set good enough to have you abandoning
    conventional TV sets? We hope to find out in a full review.

    Price: $150

    The Good
    * Good image and audio quality.
    * No visible lag.
    * Simple setup.

    The Bad
    * No 1080p or surround audio.
    * Expensive.

    What's included and setting up

    There's not much to bundle in the box with the XD, but thankfully
    Kanex has included what arguably matters the most. Besides the
    essential power adapter, the box hides both a 3-foot Mini DisplayPort
    (miniDP) cable and a 3-foot HDMI cable. As such, it's not hard to get
    started even if your source equipment doesn't have a bundled HDMI
    cable; the modern PS3 and Xbox 360 are the notable examples where this
    becomes distinctly useful. That said, the short cable length means
    you'll still be shopping for a longer HDMI cable if the source can't
    sit close by; any set-top boxes you use will probably have to sit on
    the desk itself.

    Connecting it all up is, not surprisingly, quite simple. About the
    toughest part was plugging the miniDP cable into the iMac itself,
    which required more force you'd suspect. Kanex rather thoughtfully has
    lights on both ends of the adapter, so you'll know if the miniDP cable
    or iMac isn't receiving the signal even if the XD can tell its HDMI
    source is working.

    By far the most appreciated touch is simply the nature of the format:
    because you're converting from HDMI to miniDP, both of which support
    audio on the same signal, there's no separate audio cables to plug in.
    It would be nice if there was the option to route audio separately --
    some may want to bypass the iMac entirely for this -- but the
    simplicity is hard to argue.

    There aren't any manuals, but Kanex is quick to point out that a quick
    Command-F2 shortcut will switch back to the iMac's main display.
    That's really all that's needed and a definite time saver given that
    few will unplug the XD every time.

    The one obstacle is simply the plugin order. To get the "best
    results," Kanex recommends that you first power the device, then
    connect to the XD and finally link the miniDP cable. It's logical, but
    if you have to reconnect often it could get to be a nuisance.

    Performance

    When everything is set up properly, the Kanex XD largely works as
    advertised. The all-digital signal shows no noticeable degradation or
    scaling artifacts, and audio comes out at a good volume and quality.
    We didn't detect any tangible audio or video lag with a PS3 or a Zune
    HD AV dock. That's especially important for PS3 and Xbox 360 gamers
    who might lose in a fighting game due to any significant delay between
    their input and what's on screen.

    It's here, though, that we encounter the XD's primary limitation: its
    maximum 720p resolution for many HDMI sources. Despite the iMac
    supporting up to 2560x1440 on its own, you're reduced to just a
    quarter of that resolution (1280x720) for the actual signal. We can
    somewhat understand why this is, since 720p scales neatly on the
    iMac's display, Kanex doesn't have to do elaborate scaling for the
    output to look correct. For the PS3, Xbox 360 and Zune HD, this won't
    be much of an issue since they rarely if ever output above that
    resolution. For Blu-ray players and other 1080p-capable devices, it's
    a major inconvenience; you're only sitting 2-3 feet away in normal
    situations, so you'll notice the imperfections of 720p much more than
    you would with a TV.

    The limitation is hard-coded, too. We tried plugging in our PS3 while
    it was configured for 1080p, and it simply generated a blank screen.
    This admittedly isn't likely to happen if you're setting up the PS3
    for the Kanex adapter first or if you were already using 720p, but it
    can be a definite hassle. Combine that with the spec's current
    limitation to stereo audio and you won't quite have a real home
    theater experience.

    Before we criticize Kanex too harshly, we should note that some of the
    fault here is Apple's current implementation of the 27-inch display's
    resolution modes. As of this writing, the EDID (Extended Display
    Identification Data) for the screen will only accept 16:9 aspect ratio
    input in either the iMac's native resolution or 720p. The Kanex XD
    therefore can accept 1080p -- but not from an iMac. It doesn't change
    the reality for the end user but does mean the add-on could get more
    advanced resolutions with future iMac firmware updates, if any.

    Wrapping up

    Kanex is very forthright with what the XD does and makes it as easy as
    possible to get started. If you're in a studio apartment and your
    choice is either a 27-inch iMac or a 27-inch TV, you can get the
    adapter knowing it should accept most current HD properly and will
    save you both some cash and some space.

    The operative term is, of course, "most." For $150, it's somewhat
    disappointing the adapter won't change resolution to accommodate
    1080p. What the adapter does now is good for many purposes, but we can
    see a point a few years into ownership where the Kanex XD is made
    obsolete by newer consoles or 1080p-plus TV sources.

    It's still a definite success as an adapter, but don't expect to never
    need another adapter again.
     
    bartbrn, Jul 23, 2010
    #1
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