Changing resolution on Gnome 49

[FricoRico]

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Hi there!

The chances are high this is a Gnome/Mutter specific issue, but I wanted to throw this out there anyway. After migrating from Arch Linux (running bleeding edge versions) to Fedora Silverblue I noticed that my resolution changing script causes the stream to go black before the stream starts. It could be a newly introduced bug in Sunshine, or it could be that this is an older version of Gnome where a bug is present.

My hunch is that Sunshine is unable to request XDG-Portal session after changing the resolution. The orange 'screenshare' badge also dissappears. What I also noticed is that even if there is not a stream running, the screenshare badge is still present (even from boot). Perhaps something changed in the XDG-Portal request where before it would request before the stream starts, and now it requests when Sunshine starts?

This is the badge I'm talking about:

This is my script to change the resolution that I run in the Preparation Do command:

#!/bin/sh

# Requested resolution and refresh rate
set -e

# Get params and set any defaults
width="${1:-1920}"
height="${2:-1080}"
refresh_rate="${3:-60}"
hdr_enabled="${4:-false}"

display=$(gdctl show | grep "─Monitor " | awk '{print $2}')
requested_resolution="${width}x${height}"
requested_refresh_rate=${refresh_rate}
requested_color_mode="$(if [ $hdr_enabled = true ]; then echo "bt2100"; else echo "default"; fi)"

#echo "Requested was ${requested_resolution} at ${requested_refresh_rate} Hz and color mode $requested_color_mode"

# Function to extract resolution and refresh rate from a line
extract_resolution_and_rate() {
    local line="$1"
    # Match patterns like "1920x1080@60.000"
    if [[ "$line" =~ ([0-9]+x[0-9]+)@([0-9.]+) ]]; then
        resolution="${BASH_REMATCH[1]}"
        refresh_rate="${BASH_REMATCH[2]}"
        echo "$resolution $refresh_rate"
    else
        echo ""  # Return empty if no match
    fi
}

# Function to calculate the difference between two resolutions and refresh rates
calculate_difference() {
    local res1=$1
    local rate1=$2
    local res2=$3
    local rate2=$4

    local width1=$(echo "$res1" | cut -d'x' -f1)
    local height1=$(echo "$res1" | cut -d'x' -f2)
    local width2=$(echo "$res2" | cut -d'x' -f1)
    local height2=$(echo "$res2" | cut -d'x' -f2)

    local width_diff=$(echo "$width1 - $width2" | bc)
    local height_diff=$(echo "$height1 - $height2" | bc)
    local rate_diff=$(echo "$rate1 - $rate2" | bc)

    echo "$(echo "$width_diff * $width_diff + $height_diff * $height_diff + $rate_diff * $rate_diff" | bc)"
}

# Initialize variables to track the closest match
closest_resolution=""
closest_refresh_rate=0
min_difference=99999999

resolutions_output=$(gdctl show -m)

# Read the list of resolutions and refresh rates
while IFS= read -r line; do
  if [[ $line =~ ([0-9]+x[0-9]+)@([0-9.]+) ]]; then
      read resolution refresh_rate <<< $(extract_resolution_and_rate "$line")

      difference=$(calculate_difference "$requested_resolution" "$requested_refresh_rate" "$resolution" "$refresh_rate")

      if (( $(echo "$difference < $min_difference" | bc -l) )); then
          min_difference=$difference
          closest_resolution=$resolution
          closest_refresh_rate=$refresh_rate
      fi
  fi
done <<< "$resolutions_output"

echo "Setting resolution to $closest_resolution at $closest_refresh_rate Hz"

gdctl set --logical-monitor --primary --monitor $display --mode "$closest_resolution@$closest_refresh_rate" --color-mode "$requested_color_mode"

[FricoRico]

After getting some sleep and thinking about it, it figured it out. The problem has to do with XDG-Portal which I didn't use before. On Arch it defaulted to KMS but recent changes to Sunshine made it so that XDG-Portal is the default. After forcing KMS and enabling sunshine-kms service, it works like a charm on Fedora Silverblue.

I would like to point to this issue to further explain the changes:
LizardByte/Sunshine#4666