Thread: 4k TV Displaying incorrect resolutions and refresh rates in HiDPI mode?

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  1. #1 4k TV Displaying incorrect resolutions and refresh rates in HiDPI mode? 
    I have a new Samsung 55" HU6950 4K TV and a rocket fish UHD compatible HDMI cable plugged into the HDMI port on the Mac Pro. The main problem I'm having is that my picture is out of sync with my audio from the line out Jack on the Mac Pro. I figured this might have something to do with the refresh rate of the TV.

    I came in today, and the TV had automatically updated its own firmware. Last week my display options for resolutions were correct 16 x 9 aspect ratio's, now instead of 3840x2160 I see 3840x2025. (Not sure if this is because of my update to 10.9.4 this morning? Seems these resolutions might have something to do with HiDPI mode?) My other resolutions are all also displaying new aspect ratios. So that is now a new problem. And I still cannot get 60 Hz refresh rate out of the TV. I tried using switchX but it will only allow me to do 30 HZ, I tried calling Apple and they said there is nothing they can do, the display options are given to the Mac from the TV. I called Samsung and they said to talk to Apple. Samsung didn't know what MST was, which is what Apple says to enable on the TV in order to get 60 HZ.

    I tried resetting the Pram, and now my Mac won't start up. I'm in a downward spiral. Does anyone know how to correct the audio and picture sync issues with the 4K TV connected to the Mac Pro? Is it a refresh rate issue? Or is there something else I need to change?
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  2. #2  
    One thing I noticed in your post is that you are attempting to achieve 60Hz UHD over HDMI 1.4 (the variant found in the new MacPro), but this cannot happen, as HDMI 1.4 allows for a maximum of 30Hz at UHD resolution.

    Another peculiar thing that I noticed is the aspect ratio you implied with 3840x2025 is the same aspect ratio as DCI 4K (1.9 : 1 or 4096x2160). This could be very telling, as Apple may be about ready to release a new Apple display at the true 4K resolution, and the beta OS you are running could be trying to do just that, albeit erroneously!

    I am sorry that I can't be more of an immediate help to your problems specifically, but unless that TV has DisplayPort, which I am quite certain it does not, then I can assure you that for the time being you will be stuck in a 30Hz UHD world.
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  3. #3  
    You can't get > 30Hz when operating at 4K our of the Mac Pro via HDMI. Assuming this is a 2013 "new" Mac Pro, then to get 60Hz, you need to connect using DisplayPort and the monitor must support DisplayPort v1.2 input with MST ability. Your Samsung does not have DisplayPort.

    Not sure on the 2025 vertical resolution. I have a couple theories, but most likely it is one of the modes the TV offers up and your computer likes it. Calling Apple or Samsung tech support isn't going to help you much here. Most all support people are not knowledgeable about their own newer products, let alone products from another company that you may interact with. Samsung support people won't know what MST is because they don't offer any HDTV displays with DisplayPort 1.2 and MST ability. The new Mac Pro's HDMI is v1.4 compliant and is incapable of supporting 4K @ > 30Hz via HDMI. Technically the HDMI sits atop a Thunderbolt port so it's like having a passive TB to HDMI adapter built into your system. There are some DP1.2 / Thunderbolt to HDMI 2.0 converters coming to the market late this year or early next year, probably about $160. That will allow you to get 4K 60Hz out of your new Mac Pro and into an HDMI port.
    - Jeff Kilgroe
    - Applied Visual Technologies, LLC | RojoMojo
    - Just me and my 8K Monstro VV kicking ass.
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  4. #4  
    Senior Member Blair S. Paulsen's Avatar
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    Does anyone know if the latest MacBookPro retinas have HDMI 2.0? Or at least the necessary hardware capability to support HDMI 2.0 in the future? I have searched Apple's tech specs on the latest MBPr refresh but haven't found anything definitive…

    Cheers - #19
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  5. #5  
    No and no. :(

    Latest Macbook Pro spec bump from July only offered up a couple new Intel CPUs and started giving us all 16GB RAM (maximum available) as standard on many configurations. Still the same GPU and all other hardware from the '13 refresh that brought us Thunderbolt 2. We probably won't see a proper Macbook Pro refresh until early to mid 2015 when the appropriate Broadwell CPUs are launched.

    As they have Thunderbolt2, they can deliver 4K@60Hz that way or by way of an upcoming TB2 / DP1.2 to HDMI 2.0 converter.
    - Jeff Kilgroe
    - Applied Visual Technologies, LLC | RojoMojo
    - Just me and my 8K Monstro VV kicking ass.
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  6. #6  
    Senior Member Blair S. Paulsen's Avatar
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    Thanx Jeff. Sadly, you confirmed my assumptions.

    Currently shipping TB2 based solutions like the AJA i/o 4K ($2K, really…) or the BM Ultra-Studio 4K (fan noise) are tough ROI propositions unless you regularly need the video style interfaces for your use case. In my world it's mostly about monitoring options/quality with most assets being digital files rather than being imported via SDI spigots. Obviously if you need to integrate a workstation with SDI infrastructure in a facility, then ROI on these units is different math.

    Anyone know of another alternative based on TB2? For me at least, PCIe based solutions fail the versatility/portability test.

    Cheers - #19
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