Connecting Macbook Pro (Catalina 10.15.7) Thunderbolt 2 (Mini-Display Port) to HDMI TV input

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Connecting Macbook Pro (Catalina 10.15.7) Thunderbolt 2 (Mini-Display Port) to HDMI TV input

I’m using two HDMI Output PC’s and a MacBook Pro with a Thunderbolt 2 - Mini-Display Port USB to HDMI adapter with a HDMI Switch.

The switch switches from PC to PC perfectly, but does NOT connect the Mac HDMI UNTIL I change the Display Settings.

The AirPlay Display Settings show the TV, but will not connect unless I choose to use AirPlay (which I believe diverts output to WIFi instead of the USB port).

Question – What settings do I use:

To Mirror the Macbook Pro display output to the USB output?

(I do not want to use AirPlay. This feature will not work at the event venue).

I want to be able to switch HDMI inputs (using the HDMI Switch) with all 3 computers – so the Macbook needs to keep the USB Display Port active when other HDMI ports are in use.

Thank you!

Windows

Posted on Oct 3, 2023 3:27 PM

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Answer 1

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Grant Bennet-Alder

Level 10

133,405 points

Oct 3, 2023 7:12 PM in response to JCgreenbluff

more recent Macs and MacOS are also using EDID for error monitoring, so the display needs to seem 'alive".

Whether EDID spoofing as you describe would suffice is not something Apple specifies, at least not that I have seen.

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Answer 2

Oct 3, 2023 4:40 PM in response to JCgreenbluff

<<. the Macbook needs to keep the USB Display Port active. >>

The Mac keeps any computer to display connection active -- as long as there is a display present.

High-end, Hi-color display data is at highest data rates (higher than even had drive data rates) and is unrelenting and timing sensitive. it is very resource-intensive.

If you use your switch to break the connection between the Mac and the display, the Mac senses that the display has been disconnected and the Mac does not send data to a display that is not there.

To get a Mac display to become active, you need the Mac to query the display, and the display to answer with its name and capabilities. Otherwise, the display will not be shown as present, and no data will be sent to the display. "No signal detected" is generated by the DISPLAY, not by the Mac.

This query is only sent at certain times:

• at startup

• at wake from sleep — so momentarily sleeping and waking your Mac may work

• at insertion of the Mac-end of the display-cable, provided everything on that cable is ready-to-go

• hold the Option key while you click on the (Detect Display) button that will appear in Displays preferences (from another display)

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Answer 3

JCgreenbluff Author

Level 1

5 points

Oct 3, 2023 7:09 PM in response to Grant Bennet-Alder

Grant, Thank You for the very quick response - and I know you are definitely onto the issue.

I've had some experience with EDID in the past - with older Kramer VGA switching I used a small device for each connecting computer (in line powered VGA in and out) that captured the EDID of the computer and held it in memory so that when the signal was directed to the projector, it had a very fast handshake.

This switch (HDSW0032M1 EDID) with search terms: hold video signal - brought me to this page:

https://www.firefold.com/blogs/news/edid-and-the-hdmi-handshake

Which ties in with your comments.

So, what I need to learn is how to make the Thunderbolt 2 port in a Macbook OS Monterey Version 12.6.5 system stay open and sending - (searching).

When the switch is on another HDMI port - the other ports are stagnant.

Is there a way to do that?

Thank you!

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Answer 4

JCgreenbluff Author

Level 1

5 points

Oct 3, 2023 8:29 PM in response to JCgreenbluff

Another piece of the puzzle.

Working the bugs out of this project I am using my MacBook Pro (2012) running Catalina 10.15.7

The presenter for our upcoming event has a MacBook Air (2017) running Monterey 12.6.5 He is concerned that I have the correct adapter to connect his computer to the venue's HDMI Projection system. (rightly so)

What I've remembered is that the MacBook Pro has a HDMI port built in - and I was using 1 of the 2 Thunderbolt 2 USB ports with a Belkin Thunderbolt to HDMI adapter with the switch to test it (the newer MacBook Air does not have an HDMI port). And, the test failed to keep the EDID 'handshake' in place.

However, after my last reply I thought to simply connect the HDMI to the HDMI port on my older MacBook Pro and guess what? The handshake is NOT lost!

Yes, I am amazed.

So, what I intend to do is connect the presenters MacBook Air to the switch with the Belkin Thunderbolt adapter and see if that works (switching between 2 other computers and not loosing the EDID handshake). If it does, then great! If not, I'll let him present from my MacBook Pro which also work.

But, I would think that a machine that is 5 years newer would actually work with the thunderbolt adapter since the machine does not have an HDMI port.

Crazy stuff . . .

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Answer 5

Oct 4, 2023 6:42 AM in response to JCgreenbluff

HDMI was invented for HD TV sets, 720i. It works fine when pushed up to 1080p at 8 bits/pixel, but then basic HDMI 1.0 gets a little flaky. The interface had to be tweaked to get to deep color and higher resolutions, and the HDMi developers left it the names for things vague, and did not enforce 'bright-line' standards.

This means when you go just pick cables and adapters off the rack, some stiff will work and other stuff will not, and some Users refer to getting HDMI working as "Black Magic".

HDMI cables you want for HDMI-only Displays (higher resolutions than 720p TV sets) are marked as Certified with an anti-counterfeiting tag and are labeled:

"Premium High Speed HDMI cable" or that + "with Ethernet" --OR--

"Ultra High Speed HDMI cable" or that + "48G"

Cables with No Certification tags are good for your standard 720p TV set, and not much more.

For adapters, you need to look closely at what resolutions are claimed to be supported. On a Mac, you need to stay within that specification, or your picture may break up, flicker, or fail to connect.

MacBook Pro Retina 2012 through 2015 supports HDMI at up to 1920 by 1200 through its direct HDMI port, but it may be limited to 8-bit color.

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Answer 6

Oct 4, 2023 7:49 AM in response to Grant Bennet-Alder

You may be able to configure a MacPro 2019 model with multiple PCIe-slot graphics cards that could support more displays at higher resolutions, and produce a wider stitched-together composite display.

The current Apple Mac Pro M2 Ultra version Mac Pro does not support add-in PCIe graphics cards.

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Answer 7

JCgreenbluff Author

Level 1

5 points

Oct 4, 2023 6:44 PM in response to Grant Bennet-Alder

Grant, I really appreciate your knowledge on the HDMI issue.

Today I visited the venue where our event is Monday to see if their projection equipment had changed.

Upon meeting a staff person, they told me their older equipment would not work with a MacBook (I know it used to - but this is a municipal venue - and the person I knew from the past is now retired). So be it - l know my ancient VGA switch will work if I can’t get their system to see the Mac, either one of them.

I hope this thread helps others with HDMI issues - it certainly helped me.

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Connecting Macbook Pro (Catalina 10.15.7) Thunderbolt 2 (Mini-Display Port) to HDMI TV input

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