Mpv script to enable interpolation or force vrr.

interpolate.lua

--[[
    Copyright (C) 2023  kevincs
    This program is free software; you can redistribute it and/or
    modify it under the terms of the GNU General Public License
    as published by the Free Software Foundation; either version 2
    of the License, or (at your option) any later version.
    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.
    You should have received a copy of the GNU General Public License
    along with this program; if not, write to the Free Software
    Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
    https://www.gnu.org/licenses/gpl-2.0.html
--]]

-- Script to enable VRR (on Plasma Wayland ; requires kscreen-doctor) if the video is fullscreen.
-- If the display doesn't have VRR, interpolation is enabled.
-- For mpv running under flatpak, this requires the "System Bus -> Talks -> org.freedesktop.NetworkManager" permission.

-- Settings:

-- Don't enable interpolation under this threshold.
-- For example, display is 120Hz video is 25    fps : lua -e 'print(120 % 25)' = 20, 20 is higher than 0.13 so enable interpolation.
--              display is 120Hz video is 23.976fps : lua -e 'print(120 % 23.976)' = 0.12, 0.12 is lower than 0.13 so don't enable interpolation.'
local limit = 0.13

-- Set vrr to always on for this display (run `kscreen-doctor -o` to find list of displays).
-- Here's example output of kscreen-doctor: Output: 1 DP-1 enabled connected primary DisplayPort
--                                          Output: 2 HDMI-A-1 enabled connected  HDMI
-- Valid values could be DP-1, HDMI-A-1, DisplayPort, HDMI, etc.
local VrrDisplay = "DP-1"

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local displayFPS
local foundDisplay

function main(name, vfps)
    if (mp.get_property_bool("interpolation") or vfps == nil) then
        return
    end
    local rem = 0.0
    displayFPS = math.floor(displayFPS + 0.5)
    vfps = math.floor(vfps * 100) / 100
    if (displayFPS < vfps) then
        rem = vfps % displayFPS
    elseif (displayFPS > vfps) then
        rem = displayFPS % vfps
    end
    if (rem >= limit) then
        if not (mp.get_property_bool("display-sync-active")) then
            mp.set_property("video-sync", "display-resample")
        end
        mp.set_property("interpolation", "yes")
        print("Enabled interpolation.")
    end
    mp.unobserve_property(main)
end

function start(name, dfps)
    if (dfps == nil) then
        return
    end
    displayFPS = dfps
    mp.unobserve_property(start)
    if (VrrDisplay ~= "" and foundDisplay == nil) then
        handle = assert(io.popen('flatpak-spawn --host kscreen-doctor -o | grep -Po "Output: .+?' .. VrrDisplay .. '.+? Modes:" | grep -Po "^.+enabled" | sed "s/Output: \\S* //" | sed "s/ \\S*enabled//"'))
        for line in handle:lines() do
            if (line ~= nil and line ~= '') then
                foundDisplay = line
                print("Found screen to ignore: " .. foundDisplay)
                mp.observe_property("fullscreen", "bool", vrr)
                mp.register_event("shutdown", vrr_auto)
                return
            end
        end
    end
    local test = mp.get_property("container-fps")
    if (test == nil or test == "nil property unavailable") then
        test = mp.get_property("estimated-vf-fps")
        if (test == nil or test == "nil property unavailable") then
            return
        end
        mp.observe_property("estimated-vf-fps", "number", main)
    else
        mp.observe_property("container-fps", "number", main)
    end
end

function vrr(name, forced)
    if (foundDisplay == nil or foundDisplay == "") then
        return
    end
    local mode
    if (forced == true) then
        mode = "always"
    else
        mode = "automatic"
    end
    print("Setting vrr to " .. mode .. " " .. foundDisplay)
    os.execute('flatpak-spawn --host kscreen-doctor output."' .. foundDisplay .. '".vrrpolicy.' .. mode .. ' &> /dev/null &')
end

function vrr_auto()
    vrr("vrr_auto", false)
end

-- Wait until we get a video fps.
function check()
    mp.observe_property("display-fps", "number", start)
end

mp.register_event("file-loaded", check)