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PostPosted: Tue Apr 10, 2018 4:50 pm 
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I'm trying to connect several 13" MacBook Pro retina models to a cheap Insignia 4k TV, but unlike every other person on the entire Internets, I want the resolution to be 1920 x 1080 at 60 Hz (using the HDMI port).

It seems like this should be a simple thing. The MacBook Pro is clearly capable to outputting 1080p at 60 Hz, and the television is clearly capable of displaying it. In fact, I tested the TV in the store on a 13" MBP retina (2015 model) and it displayed everything in pixel perfect perfection at exactly this setting, but that was with an older version of OS X.

The problem is that OS X 10.13 doesn't allow a single resolution at 60 hz while connected to this TV. None. You get 30 Hz or 24 Hz, and NOTHING else. You can choose from a variety of resolutions, high and low (holding down the option key and clicking "scaled"), but still nothing at 60 Hz. WTF?

It wouldn't actually work in deployment, but I thought, OK, I'll try SwitchResX. No dice. Can't get a single 60 Hz resolution with that either.

I can if I string together a long enough God-forsaken centipede of adapters out of the Mini DisplayPort, but that's also not really a solution.

Why would Apple have removed any ability to select 60 Hz at any resolution at all, and how in the Hell can I get it back?

Bonus points: It's very hard to coax the computer in to sending an Honest To God 1080p signal to the monitor in the first place. It really, really, really wants to send a high DPI 4k signal instead, with the Mac pretending it's 1920 x 1080 like it does on a "retina" display. No. I want a real 1080p signal. Oddly, you can select "low resolution" versions of most the other resolutions, but not 1080p.

By the way, when I tested this and it was working on earlier versions of OS X, the choice in the Displays preference pane was "1080p." That's just missing in 10.13 and it sucks.

- Anonymous :( :nothappy:


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PostPosted: Tue Apr 10, 2018 9:02 pm 
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I messed with SwitchResX some more and got 1080p @ 60Hz working (not sure what I did differently), but now I can't get 4:4:4 color working, which was previously working great with my adapter tangle through the Mini Display Port.

- Anonymous


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PostPosted: Wed Apr 11, 2018 7:05 am 
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You think this would affect anyone on 10.13 with an external monitor? Thinking my Mini + 23" Dell.


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PostPosted: Wed Apr 11, 2018 8:21 am 
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Its likely a quirk of Apple assuming nobody would ever want to drive a 4K display at 1080p. If you want to drive your display at its maximum resolution you'll likely be peachy.

What if you used an older HDMI adapter, one that supported a maximum of 1080p?

Given all the software that Apple broke with 10.13 I've been staying away from it. However it is heartening to see that they support eGPUs in the latest release of 10.13. Hopefully they don't come up with some god-awful licensing program in 10.14 and only support adapters in those housings. You know, for kids.


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PostPosted: Wed Apr 11, 2018 5:14 pm 
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Have you tried holding down the option key in the Displays preferences and clicking the scaled radio button in the Displays prefpane? It should open up all options, including the 60 Hz option in the pulldown menu for refresh rate.

If that fails (and it shouldn't), then you may need to put the Insignia TV into PC mode, which should then allow proper EDID data transfer to happen on the HDMI channel so that the Mac can see that it does in fact have a 1080p60 mode.

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PostPosted: Wed Apr 11, 2018 6:04 pm 
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MonkeyBoy wrote:
Its likely a quirk of Apple assuming nobody would ever want to drive a 4K display at 1080p. If you want to drive your display at its maximum resolution you'll likely be peachy.

What if you used an older HDMI adapter, one that supported a maximum of 1080p?

Given all the software that Apple broke with 10.13 I've been staying away from it. However it is heartening to see that they support eGPUs in the latest release of 10.13. Hopefully they don't come up with some god-awful licensing program in 10.14 and only support adapters in those housings. You know, for kids.

Inexplicably, I can plug together a sequence of adapters from Mini Display Port ---> (other formats) ---> HDMI to get a perfect image (at least on OS X < 10.13), but I can't find any set of HDMI ---> (other formats) ---> HDMI to get a good signal on 10.13.

I've tried at least four different HDMI adapters, and none of them do the job, even in combination with other weird adapters. Over the computer's HDMI port I've tried active adapters, passive adapters, DVI --> HDMI adapters, 4K-capable adapters, supposedly definitely not 4K capable adapters, different brands, different HDMI cables...no happiness. I've also ordered a cheap EDID injection box with a dial that lets you choose an EDID from a dozen or so pre-programmed choices, but it won't be here for a few weeks.

The monitor itself has a game mode which reduces input lag, but doesn't improve anything else. There's no other PC mode and the "advanced settings" aren't very advanced. Holding down the option key to select a scaled resolution gives more choices, but none of them are an Honest To God 1080p signal (even with the "show low resolution modes" option selected) and none allow 60 Hz.

With game mode on and a 1920x1080 "equivalent" 4K high-DPI mode selected, the picture and response are adequate, but not satisfying.

Fortunately the sad old non-retina MBPs do the right thing without any arm twisting, and the newest MBPs with USB C ports also do the right thing through their Apple multi-adapter dongle, which supports 60 Hz even at 4K resolution (albeit not 4:4:4 chroma resolution, but most people won't notice).

- Anonymous


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PostPosted: Fri Apr 13, 2018 8:21 pm 
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Could you post what exact model of TV you have? Game Mode is never what you want on a PC because almost all TVs' "Game Modes" still use chroma subsampling. There's almost always a very specific set of steps you need to take in the menus to activate a "PC Mode". Hopefully with the model # and the associated manual I can help you figure out which steps to take (if possible - Best Buy really cheaped out on these TVs in the race to the bottom).

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PostPosted: Wed May 02, 2018 11:00 am 
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UPDATE: At least one of the TVs is working well enough, and it's not thanks to Apple and whatever f'd up thing it's doing with the HDMI port in 10.13.

I plugged in an EDID injector between the TV and the computer. The $20 device has a rotary switch to let you select a specific resolution. OS X basically ignores everything if the EDID indicates a resolution of 1080p or higher: instead, the Mac just outputs a 4K 30 Hz signal with a HiDPI resolution equivalent to 1080p (you can choose a full 4K resolution). If I set the EDID to indicate a lower resolution, it limits the TV to that lower resolution and generally makes everything bad.

BUT...the EDID injector also has a "pass through" mode where it directly copies the EDID from the TV. Inexplicably, in this mode, where the EDID is supposedly identical to what the TV is sending, I get a 4K 30 Hz 4K signal with no chroma subsampling (4:4:4) -- Pixel perfect -- whereas chroma subsampling was present without the EDID injector. That's good enough for me with the TV in game mode so the input lag is tolerable, despite running at 30 Hz.

It still won't do 60 Hz at 1080p, but I haven't tried SwitchResX again with the EDID injector to see if I can coax that in to running without chroma subsampling.

Bottom line: Apple is doing something very, very strange with the HDMI port in 10.13, and the problem doesn't completely affect the Mini DisplayPort, and it started sometime after OS X 10.9.

For record the TV is an Insignia NS-50DR620NA18. It's software version is 8.0.0, build 4183-31. The second TV is the 55" version of the same model. I did end up renaming the default HDMI input "Computer" but this is mostly to avoid confusion by people using it and has no effect on the TV's behavior/image.

- Anonymous


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PostPosted: Wed May 02, 2018 1:44 pm 
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Whew, good work. :)


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PostPosted: Wed May 02, 2018 6:45 pm 
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If you're in game mode, you've still got chroma subsampling. The output signal might be 4:4:4 going to the TV, but the TV is still processing it. The only time chroma subsampling is turned off entirely is in PC Mode.

Edit: After going through massive hoops to get to a user manual (thanks Insignia/Best Buy for not providing the full manual on your support site), it does not appear this TV even has a proper PC mode, so chroma subsampling is always active. Unless of course the manual so thoughtfully omits the PC mode info...which wouldn't surprise me one bit with how cheaply the manual appears to have been done.

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PostPosted: Thu May 03, 2018 5:15 pm 
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Nope, no chroma subsampling. I'll try to remember to post photographs of the screen when I get home and get them off the phone.

- Anonymous


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PostPosted: Fri May 04, 2018 12:08 am 
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See attached photos of 100% crops of a test image. These were taken at of a png test image displayed from a 2015 13" MacBook Pro over that machine's HDMI port at the Insignia NS-50DR620NA18 native 3840 × 2160 resolution at a refresh rate of 30 Hz in Insignia's "game mode" through an HDMI cable with an intervening EDID injector in "pass-through" mode.

I can take cleaner versions of these if they're not convincing: the mild blurriness evident, especially in the bottom photo, is due to operator inattention while using my phone's moderately crummy camera.

Image

Image

- Anonymous


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