Better custom resolution support for display managed hardware PBP (Picture by Picture) mode switching

[parthpat12]

Have Dell U3818DW (3840 x 1600) and there is a feature called PBP which allows me to view multiple inputs connected to the same monitor side by side. The issue is, when I turn this on, resolution does not automatically change to 1920 x 1600.

This also applies when remote in from iPad. It's be nice to auto change resolution to fit iPad's retina screen instead of remaining at 3840x1600.

[waydabber]

PBP implementation is not really standardized, changes from display to display. Some displays do disconnect and reconnect as a new display with different EDID (with different aspect ratio resolution list) when PBP is enabled - for these displays the OS does switch. Other displays don't do this, they simply have PBP and non-PBP resolutions mixed in a single EDID. The OS has no idea that PBP is enabled or not.

auto change when connecting from iPad is a different story. I think this should be handled by the app/service that is used for remote connection. Since there are a number of tools by different vendors, I don't think there is a generic solution for this.

[waydabber]

I'll convert this into a discussion so others might chime in.

[meanaverage]

I'm having a similar issue, but it also stems from lazy manufacturer (identical serial numbers).

Configuration:
(1) ThinkVision P32u-10. Native pixel resolution 3840x2160. (as Monitor 1) -- TB3 pass through connection.
(1) ThinkVision P32u-10 in PBP mode. (as Monitor 2 and Monitor 3) -- TB3 & DP.

I need to be able to set a custom native panel pixel resolution of 3840x1080 for monitors 2 and 3 so that I can ultimately get HiDPI resolutions in 32:9 (or 8:9 if doing left<-> right) aspect ratio. However, doing so disables me from using proper HiDPI resolutions on Monitor 1 then because any EDID override I do applies to ALL monitors since there is no distinction between them.

I'm considering just getting an HDMI adapter for EDID override via hardware prior to input, but I think there has to be another way? :(

[waydabber]

On Apple Silicon you can add EDID overrides one-by-one (but macOS might have an issue distinguishing between displays if they have the same serial number), on Intel the override will affect all displays with the same identifiers. If you use HDMI and can find a suitable EDID dongle, that's a safe solution indeed.

[meanaverage]

Sounds like it's time for a Mac Studio instead. Thanks for the info. GAHHH!!!

What constitutes an identifier? Is it VENDOR/PRODUCT ID or VENDOR/PRODUCT ID/SERIAL? Is this somewhat configurable at all or is it simply baked into the OS? It does seem like at least for Intel there may be no way to actually 'create' a unique ID that is respected, as there may be no way to implement a solution that addresses/add another variable which is considered for uniqueness (such as the before talked about alphanumerical serial potential).

Currently using DP and TB3 only. Could use HDMI if it's a workaround but obv not ideal as for most users with sub-modern monitors HDMI has it's limitations.

[waydabber]

VENDOR/PRODUCT ID/SERIAL. It's baked into the OS... :/

[meanaverage]

Adding link here for others to see my comments re: PBP/Lenovo monitor frustration and as a warning about DCC adjustment through software when using PBP.
#1759 (comment)

[peterjcole]

Kind of relevant to this thread, but let me know if I should put this in a new thread or an issue:

Is there any possibility of BetterDisplay supporting the switching on and off of monitor PBP/PBP features via DDC? These are supported by the mac software for my (Dell) monitor

Appreciate that the lack of standardisation could make this unfeasible!

[waydabber]

Hi there, I could add a feature like this if you know the right DDC codes for the specific display. I plan to add custom DDC commands as well. Right now you can use betterdisplaycli to invoke the command if you know the right command code.

[peterjcole]

Thanks for pointing that out @waydabber! I managed to turn on PBP via the code I found here: rockowitz/ddcutil#268

betterdisplaycli set -namelike=dell -ddc -vcp=0xe9 -value=0x23

Setting it back to 0 switched it off, although it seems to scan for an active input afterwards rather than going back to the mac input which was previously selected

Support for custom codes in the BetterDisplay UI would be really useful! I noticed in a PR linked to that issue that your m1ddc tool supports PIP commands as a specific feature as well.