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Mac: Keychron loses connection and MacBook HDMI hell continues with a side helping of LG glitching on optical output

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OK, I was away from my main keyboards for about three weeks and it was interesting to see what happened, the biggest thing is that after upgrading to Ventura, I could not get any Bluetooth connection to my Keychron K6 it would just not pair properly, so here are some of the things to do and some of the keyboard shortcuts:

  1. Is the Battery dead? Well, that was the first question and it turns out there is no application like Anne Pro has, the trick is that you need to hold the FN1+B key, and then you will get a basic readout that if everything lights it is 70-100% if the first row if dark then it is 30-70% and if less than 30% then the first two rows will be dark.
  2. Try to start the BlueTooth connection, you do this by pressing the FN1 and then Q, W or E depending on which Bluetooth connection you want 1, 2, or 3. Hold it for 4 seconds and this should force a pairing.
  3. As an aside, you can change the backlight with FN1 and the backlight at the upper right to turn it on and off and keep pressing the Backlight to change the mode.
  4. To do a full reset and start over, hold FN1+Z+J for 4 seconds and it will reset everything, this is what actually worked for me. Doing that plus the FN1+Q worked. There is a note that you sometimes have to switch the connection you use to make it work so I did that. I was using FN1+W and this didn't work but switching ports did.
  5. It's interesting to see when I did that the Bluetooth search finally worked on the Mac and it showed the old profile which makes me think yes, it was an interaction with the Mac that was the problem. But remember that easy to remember FN1+Z+J if you have a problem

Mac to LG to Denon AVR: HDMI audio glitching needed LG reset

This started with Big Sur, but suddenly the HDMI audio output is clicking and whining. The audio itself seems to work fine and the output to the AVR works fine, but not for this HDMI audio output. I'm kind of confused by this, it could be this flaky Razor Thunderbolt 4 deck I'm using

This one has been nagging me for a long time, but most of the times, the Mac output is not recognized unless I switch to TV output and sometimes when I reset the Razor, I think this is another potential interaction with this LG B9 or the Razor, it is hard to debug, but I'm thinking about taking the Razor out of the lop and see if that helps.

Diagnosing this is a classic example of removing things:

  1. I removed the Razor Thunderbolt 4 dock from the equation and it still seems to happen. The audio is still not right so it is not that box
  2. I am using a Cable Matters 48Gbps USB C to HDMI adapter that converts from USB C/DisplayPort alternative mode to HDMI, so now I need to find another connector and see if this happens so I just plugged it into the HDMI 2.0 port that is there, and the audio magically cleared up. So it could be the Cable Matter cable net, net, we will have to see if the loss of video happens.
  3. The HDMI cable then worked for a bit and then distorted again, so it could be either the HDMI Input or bad interpretation by the Denon.
  4. So when I convert it just to the TV Speakers it works great, so it is the Denon that is having trouble it's an old one.
  5. So I just flipped the LG from PCM to Bitstream mode and back and it worked. It does seem like a glitch in passing the bitstream.
  6. So this is a good example of removing enough components to see what the issue is, but with the thing plugged in directly, it does seem to work. As an aside this happened on both Venture and Big Sur, so it was clear it was no an OS problem.

Net, net more testing needed, but something happened with the Cable Matters connector apparently it could either be bad or it could be that somehow the driver is not working right.

The Cable Matters works on the MacBook Air 2022 to LG C2 as well

Ok this is interesting, the Cable Matter cable does support 48Gbps and does handle HDR correctly, you need at least HDMI 2.0 to support 4K HDR at 4:2:2 levels in color compression, but it looks like the long Deep well of color compression on MacBook which with HDMI 2.1 has the full 48Gbps so the LG B9 (and the LG CX and C2 that we have) can all theoretically support 12-bit color at 4K@120Hz at 4:2:2 compression. Note that internally, these panels are only really doing 4:2:2, so now reason to send 4:4:4 full color. The main issue is that MacBook Pro is just HDMI 2.0 so it is limited to 4K@60 4:2:2 at 8 bpc but you can do 4K@120 if you have a DisplayPort monitor (that is not just a TV, but a real PC monitor).

Uni USB C to HDMI Adapter no HDR but 4K@60

Also, one aside, picking your cable carefully matters, for instance, we got the no-name Uni USB C to HDMI Adapter. This says it supports 4K@60Hz but in testing, it does not support HDR because of the data rates. it does not say what the data rate is or what compression it is supporting, but this is a common problem, so right now, the Cable Matter 48Gbps seems to work for the MacBook Air 2022, but no longer for the MacBook Pro 2021. Weird!

Will Glitching be fixed by attaching directly to the HDMI 2.0 MacBook Pro port

This is the thing to test now, is the no screen problem related to the adapter or to the Thunderbolt deck. So right now just using the HDMI 2.0 on the MacBook Pro directly and seeing how it does

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