DDC volume control doesn't work on LG C2 42"

[admin-hsu1]

Can you advise how I can get it to work?
The brightness works flawlessly, but as for volume control, I tried everything w/o any luck.

[Device list]
Macbook M1 Max
↓
Cable Matters USB-C to HDMI 2.1 adapter (chipset: VM6100)
↓
HDMI 2.1 cable
↓
LG C2 42"

ref: https://forums.macrumors.com/threads/dp-usb-c-thunderbolt-3-4-to-hdmi-2-1-4k-120hz-rgb4-4-4-10b-hdr-with-apple-silicon-m1-m2-now-possible.2381664/

Thank you!

[waydabber]

Hi there - The LG C2 does not support DDC so brightness control does not work properly by default (only the lower half of the scale should be working which is software dimming). You need to disable DDC under Settings/Displays for that display to make the brightness slider work with the full range.

Similarly, volume control does not work over DDC. You can try using an app that acts as an audio device filter like eqMac and adjusts output audio levels.

[MichaelZhou]

Hi @waydabber, I have a couple questions:

What's the difference between software dimming and hardware dimming? Will software dimming still lower the OLED pixel brightness of my LGC2 and protect it from burn-in?

Can you explain how to disable DDC on this display?

[waydabber]

Hi, under the display's settings (in app Settings) simply turn off "Enable DDC control". Software dimming changes the colors of the screen at the Mac's side while hardware dimming asks the display to do so. Software dimming will also lower OLED pixel brightness and protect from burn-in.

[lschenatto-hrp-ctr]

I'm facing the same problem with a DELL S3422DW.
Brightness works like a charm, but volume control doesn't do anything.

Is there a way to get it to work?

[waydabber]

Does volume control work with the display's own software? It is well understood that TVs don't support DDC (I plan to add networked control and HDMI-CEC in some future releases to improve the situation somewhat - the later is heavily hardware dependent though) but the S3422DW might support DDC volume control (not sure - many displays simply don't have support for that).

[lschenatto-hrp-ctr]

The display's manual (page 43) state that it does support DDC, and there is an option to enable/disable DDC on the display's settings. Although I don't know if it is a problem on the monitor or BetterDisplay...

What do you mean by display's own software? Not sure if that's the question, but it works if I change it manually on the monitor's menu.

BTW, thanks for the reply!

[waydabber]

I mean Dell typically provides an app of some kind (but maybe only for Windows) to control its displays. If it has volume control feature, there is a good chance that it supports volume control. Generic DDC support does not necessarily mean there is DDC volume support. Does the app detect it as capability (when you run DDC auto configuration in the app)?

[lschenatto-hrp-ctr]

It doesn't detect it as DDC capable.
Maybe a problem on the cables or, in the end of the day, the monitor doesn't support it, although it says it does...

Anyways, thanks for the support.

[waydabber]

Hmm. If it does not detect it as DDC capable at all, then it might indeed be the connection or you need to explicitly enable DDC/CI on the display (some displays have a toggle for that somewhere buried in the display's OSD).