Mac Mini HDMI showing wrong display size

[Astrohunter]

Hi,

I had this issue on both M1 and M4 Pro Mac Mini.
My 55" OLED TV from LG shows as 72" in settings.

I don't know if it affects scaling in any way, but is it possible to override it anyhow?

Thanks

 

[FreakinEurekan]

Likely it's just a cosmetic issue. 55" and 72" TVs tend to have the exact same resolution, e.g. 3840 x 2160 pixels for 4k. So no, it wouldn't affect scaling in any way.

check with LG to see if there's a firmware update.... if not ¯\_(ツ)_/¯ ignore it.

 

[Alameda]

Diagonal size is not part of the EDID specification, to my knowledge. There’s just a string that describes the device which can be read over HDMI. At the end of the day, it doesn’t matter whether it’s a 15 inch or a 500 inch display, if the resolution is the same.

 

[Astrohunter]

Diagonal size is not part of the EDID specification, to my knowledge. There’s just a string that describes the device which can be read over HDMI. At the end of the day, it doesn’t matter whether it’s a 15 inch or a 500 inch display, if the resolution is the same.

I just have a feeling that on my M1 with HDMI 2.0 I had a slightly different scaling options, at least the higher ones.
But maybe it's just my bad memory.

 

[joevt]

Diagonal size is not part of the EDID specification, to my knowledge. There’s just a string that describes the device which can be read over HDMI. At the end of the day, it doesn’t matter whether it’s a 15 inch or a 500 inch display, if the resolution is the same.

EDIDs can specify vertical and horizontal maximum image dimensions (in centimeters) as well as dimensions per display mode (in millimeters).

There's an EDID for LG OLED 55C7 at https://www.edid.tv/edid/896/

I downloaded it and used edid-decode to decode it.

The description correctly states "LG OLED 55C7".
It has these sizes:

Maximum image size: 160 cm x 90 cm

    DTD 1:  3840x2160   60.000000 Hz  16:9    135.000 kHz    594.000000 MHz (1600 mm x 900 mm)
                 Hfront  176 Hsync  88 Hback  296 Hpol P
                 Vfront    8 Vsync  10 Vback   72 Vpol P
    DTD 2:  1920x1080   60.000000 Hz  16:9     67.500 kHz    148.500000 MHz (1600 mm x 900 mm)
                 Hfront   88 Hsync  44 Hback  148 Hpol P
                 Vfront    4 Vsync   5 Vback   36 Vpol P

Those compute to 72 inches:

bc <<< "scale=13; sqrt(1600^2 + 900^2) / 25.4"
72.2738572861646

perl -E "print sqrt(1600**2 + 900**2) / 25.4"
72.2738572861646

which is incorrect. I guess they got lazy when editing the EDID.

Maybe you can override the EDID using @waydabber 's BetterDisplay.app . I don't know if macOS will read the dimensions from the override. I don't know if the dimensions are used in DPI calculations for choosing display modes.
https://forums.macrumors.com/threads/5k2k-at-120hz-with-mac-mini-m4.2441289/post-33911453

 

[Alameda]

EDIDs can specify vertical and horizontal maximum image dimensions (in centimeters) as well as dimensions per display mode (in millimeters).

There's an EDID for LG OLED 55C7 at https://www.edid.tv/edid/896/

I downloaded it and used edid-decode to decode it.

The description correctly states "LG OLED 55C7".
It has these sizes:

Maximum image size: 160 cm x 90 cm

    DTD 1:  3840x2160   60.000000 Hz  16:9    135.000 kHz    594.000000 MHz (1600 mm x 900 mm)
                 Hfront  176 Hsync  88 Hback  296 Hpol P
                 Vfront    8 Vsync  10 Vback   72 Vpol P
    DTD 2:  1920x1080   60.000000 Hz  16:9     67.500 kHz    148.500000 MHz (1600 mm x 900 mm)
                 Hfront   88 Hsync  44 Hback  148 Hpol P
                 Vfront    4 Vsync   5 Vback   36 Vpol P

Those compute to 72 inches:

bc <<< "scale=13; sqrt(1600^2 + 900^2) / 25.4"
72.2738572861646

perl -E "print sqrt(1600**2 + 900**2) / 25.4"
72.2738572861646

which is incorrect. I guess they got lazy when editing the EDID.

Maybe you can override the EDID using @waydabber 's BetterDisplay.app . I don't know if macOS will read the dimensions from the override. I don't know if the dimensions are used in DPI calculations for choosing display modes.
https://forums.macrumors.com/threads/5k2k-at-120hz-with-mac-mini-m4.2441289/post-33911453

It doesn’t make any difference though. A 1080p or 4K HDMI signal is the same no matter how large the screen.