Ultrawide monitors with PBP (Picture by Picture) are becoming more common these days. It allows you to split the screen and connect multiple sources to your monitor (e.g. 2 computers at the same time)
The problem is that the resolution is typically not supported out of the box (E.g. a 2560x1080 monitor, when split into 2 will require a 1280x1080 resolution, which is not standard in Mac OS as of Sierra)
First, we have to reboot in rootless mode, and disable the Integrity Protection, so we can create/override the screen file settings:
- Reboot the Mac and hold down Command + R keys simultaneously when it restarts, this will boot OS X into Recovery Mode
- When the “OS X Utilities” screen appears, pull down the ‘Utilities’ menu at the top of the screen instead, and choose “Terminal”
- Type the following command into the terminal then hit return:
csrutil disable; reboot
The Mac will then reboot itself automatically, just let it boot up as normal. Source
Second, we need to find out your display configuration settings
- Connect your non-compliant monitor and switch into the PBP mode
- Open a terminal
- Run this command:
ioreg -lw0 | grep IODisplayPrefsKey
You'll get something like these results:
| | | | "IODisplayPrefsKey" = "IOService:/AppleACPIPlatformExpert/PCI0@0/AppleACPIPCI/IGPU@2/AppleIntelFramebuffer@0/display0/AppleBacklightDisplay-610-a034"
| | | | | "IODisplayPrefsKey" = "IOService:/AppleACPIPlatformExpert/PCI0@0/AppleACPIPCI/IGPU@2/AppleIntelFramebuffer@1/display0/AppleDisplay-1e6d-59f1"
One of the settings is for your Macbook laptop monitor (AppleBacklightDisplay-610-a034), and the other is for the connected display (AppleDisplay-1e6d-59f1). The naming follows a convention: The first part e.g. 1e6d is the hexadecimal version of the DisplayVendorID, while the second one 59f1 is the DisplayProductID.
Go ahead and get the decimal values for those. You can use something like this site: http://www.binaryhexconverter.com/hex-to-decimal-converter to do it online.
1e6d (Display Vendor ID) = 7789
59f1 (Display Product ID) = 23025
With this info at hand, let's go and modify (or create if it doesn't exist) the file that will hold our customn settings
Third, create/modify the DisplayProduct file.
From the terminal or finder, navigate to /System/Library/Displays/Contents/Resources/Overrides/DisplayVendorID-xxxx, where xxxx is the hex value of the Display Vendor ID from above (e.g. DisplayVendorID-1e6d)
Then, open a text editor as an admin (or get ready to be prompted for your password upo saving later). Open the file named DisplayVendorProductID-yyyy, where yyyy is the Display Product ID from above (e.g. DisplayProductID-59f1). Make sure there is no file extension. If this file doesn't exist, create it.
Fourth, enter the DisplayProduct ID info.
Other than the DisplayProductID and the DisplayVendorID (that are now in decimal instead of hex), that should be self-explanatory, the other things here are:
- DisplayProductName, which can be any name,
- IODisplayEDID - Data, which I copied from another file in the same directory (e.g. `DisplayProductID-76db') because I noticed it shared the same DisplayVendorID for the monitor I was trying to configure (most likely because this is the non-PBP version of the driver)
- dspc - data, which I got from somebody that used SwitchResX :p
Here is the final file:
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>
<key>DisplayProductID</key>
<integer>23025</integer>
<key>DisplayProductName</key>
<string>SS Settings - LG ULTRAWIDE</string>
<key>DisplayVendorID</key>
<integer>7789</integer>
<key>IODisplayEDID</key>
<data>AP///////wAebdt2AQEBATIXAQSlUCJ4nsqVplVOoSYPUFQhCABxQIGAgcCpwLMA0cCBAAEB53xwoNCgKVAwIDoAIE8xAAAanWdwoNCgIlAwIDoAIE8xAAAaAAAA/QA4PR5aIAAKICAgICAgAAAA/AAzNFVNOTUKICAgICAgAVECAxFxIwkGB0QQBAMBgwEAAAI6gBhxOC1AWCxFACBPMQAAHn5IAOCgOB9AQEA6ACBPMQAAGAEdAHJR0B4gbihVACBPMQAAHowK0Iog4C0QED6WACBPMQAAGGs+uFBgoClQCCC4BCBPMQAAGp89cKDQoBVQMCA6ACBPMQAAGgAAcg==</data>
<key>dspc</key>
<array>
<data>
KScA4FA4H0BAQDoAAAAAAAAY
</data>
</array>
</dict>
</plist>
Alternatively, if you don't feel very good at using the dspc key, and instead just want to have custom resolutions, the way is to use the scaled-resolutions key. Just replace the dspc section with something like this:
<key>scale-resolutions</key>
<array>
<data>
AAAFAAAABDgAAAAB
</data>
</array>
That weird data value (AAAFAA...) is generated by converting the decimal values of the resolution into hexadecimal, into binary, into base64.
If it's too confusing, no worries, here is a little bash that you can do to get the values:
echo $(printf '%.8x%.8x%.8x' WIDTH HEIGHT 1) | xxd -r -p | base64
e.g. (for a 1280x1080)
echo $(printf '%.8x%.8x%.8x' 1280 1080 1) | xxd -r -p | base64
Then just plug the result into the file and voila!
PS. In case you want to "decode" the string, it is something like this (needs to be optimized):
- E.g. for the data value AAAFAAAABDgAAAAB, in bash,
echo AAAFAAAABDgAAAAB | base64 --decode | xxd - Take the result (e.g.
0000 0500 0000 0438 0000 0001), and run them through the hexadecimal to decimal converter in groups of 8 numbers. E.g. 0000 0500, 0000 0438, 0000 0001 - This should give you 1280, 1080 and 1, which is the screen resolution (1280x1080)
PS2. Don't forget to turn on the integrity protection csrutil enable
For further reference..
In case you are lazy like me, install switchresx trial, configure your monitor on a custom setting (much easier than by terminal), then backup your file at '/System/Library/Displays/Contents/Resources/Overrides/DisplayVendorID-xxxx'. Uninstall switchresx (not so easy as it should). Put the file back in there... And voila, same result.