Skip to content

Instantly share code, notes, and snippets.

@adaugherity
Forked from BugRoger/patch-edid.rb
Last active October 12, 2024 00:32
Show Gist options
  • Save adaugherity/7435890 to your computer and use it in GitHub Desktop.
Save adaugherity/7435890 to your computer and use it in GitHub Desktop.
#!/usr/bin/ruby
# Create display override file to force Mac OS X to use RGB mode for Display
# see http://embdev.net/topic/284710
require 'base64'
data=`ioreg -l -d0 -w 0 -r -c AppleDisplay`
edids=data.scan(/IODisplayEDID.*?<([a-z0-9]+)>/i).flatten
vendorids=data.scan(/DisplayVendorID.*?([0-9]+)/i).flatten
productids=data.scan(/DisplayProductID.*?([0-9]+)/i).flatten
displays = []
edids.each_with_index do |edid, i|
disp = { "edid_hex"=>edid, "vendorid"=>vendorids[i].to_i, "productid"=>productids[i].to_i }
displays.push(disp)
end
# Process all displays
if displays.length > 1
puts "Found %d displays! You should only install the override file for the one which" % displays.length
puts "is giving you problems.","\n"
elsif displays.length == 0
puts "No display data found! Are any external displays connected?"
puts "\nNote: Apple Silicon (arm64) devices are currently unsupported, as the standard"
puts "method of retrieving display information does not work."
end
displays.each do |disp|
# Retrieve monitor model from EDID display descriptor
i = disp["edid_hex"].index('000000fc00')
if i.nil?
monitor_name = "Display"
else
# The monitor name is stored in (up to) 13 bytes of text following 00 00 00 fc 00.
# If the name is shorter than 13 bytes, it is terminated with a newline (0a) and then padded with spaces.
monitor_name = [disp["edid_hex"][i + 10, 26].to_s].pack("H*")
monitor_name.rstrip! # remove trailing newline/spaces
end
puts "Found display '#{monitor_name}': vendor ID=#{disp["vendorid"]} (0x%x), product ID=#{disp["productid"]} (0x%x)" %
[disp["vendorid"], disp["productid"]]
puts "Raw EDID data:\n#{disp["edid_hex"]}"
bytes=disp["edid_hex"].scan(/../).map{|x|Integer("0x#{x}")}.flatten
puts "Setting color support to RGB 4:4:4 only"
bytes[24] &= ~(0b11000)
puts "Number of extension blocks: #{bytes[126]}"
puts "removing extension block"
bytes = bytes[0..127]
bytes[126] = 0
bytes[127] = (0x100-(bytes[0..126].reduce(:+) % 256)) % 256
puts
puts "Recalculated checksum: 0x%x" % bytes[127]
puts "new EDID:\n#{bytes.map{|b|"%02X"%b}.join}"
Dir.mkdir("DisplayVendorID-%x" % disp["vendorid"]) rescue nil
filename = "DisplayVendorID-%x/DisplayProductID-%x" % [disp["vendorid"], disp["productid"]]
puts "Output file: #{Dir.pwd}/#{filename}"
f = File.open(filename, 'w')
f.write '<?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">'
f.write "
<dict>
<key>DisplayProductName</key>
<string>#{monitor_name} - forced RGB mode (EDID override)</string>
<key>IODisplayEDID</key>
<data>#{Base64.encode64(bytes.pack('C*'))}</data>
<key>DisplayVendorID</key>
<integer>#{disp["vendorid"]}</integer>
<key>DisplayProductID</key>
<integer>#{disp["productid"]}</integer>
</dict>
</plist>"
f.close
puts "\n"
end # displays.each
@GetVladimir
Copy link

@MikaelDDavidd This solution works on x86 based Macs. It's not meant for M1 based Macs, as they ignore the EDID override.

You can delete the override file you have created, reboot and it should be back to default.

If possible, try using an USB-C to DisplayPort port cable on the M1 Pro

@flawnn
Copy link

flawnn commented Sep 24, 2024

Any way to make this work with BetterDisplay? It also works on Silicon-based Macs.

Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment