modetest.py

#!/usr/bin/env python3
from collections import namedtuple
import pprint
import subprocess
import sys

pp = pprint.PrettyPrinter(indent=4)

def call_modetest():
    try:
        result = subprocess.run(['modetest', '-c'], check=True, capture_output=True, text=True, errors='replace')
    except subprocess.CalledProcessError as e:
        print(e, file=sys.stderr)
    else:
        return result.stdout
  
Mode = namedtuple('Mode', ['connection', 'resolution', 'refreshrate'])

def sort_modes(mode: Mode):
    preferred_rrates = [50, 60, 30, 24]
    preferred_resolutions = ['3840x2160', '1920x1080', '1280x720']
    preferred_outputs = ['HDMI', 'DP', 'DVI', 'VGA']

    connection_score = 0
    rrate_score = 0
    resolution_score = 0

    if mode.resolution.endswith('i'):
        resolution_score -= 1
        resolution = mode.resolution[:-1]
    else:
        resolution = mode.resolution

    if mode.refreshrate in preferred_rrates:
        rrate_score = len(preferred_rrates) - preferred_rrates.index(mode.refreshrate)
    if mode.resolution in preferred_resolutions:
        resolution_score = len(preferred_resolutions) - preferred_resolutions.index(mode.resolution)
    x_resolution, y_resolution = (int(n) for n in resolution.split('x'))
    connection = mode.connection.split('-')[0]
    if connection in preferred_outputs:
        connection_score = len(preferred_outputs) - preferred_outputs.index(connection)
    return (rrate_score, resolution_score, x_resolution, y_resolution, connection_score)


def parse_modetest(data):
    connectors = {}
    mode_list = []
    for line in data:
        if "connected" in line:
            conn_id, encoder, status, name, size, modes, encoders = line.split()
            if status == 'disconnected':
                connectors[name] = {'connected': False, 'modes': set()}
            else:
                connectors[name] = {'connected': True, 'modes': set()}
                if "modes:" in next(data):
                    next(data)
                    while True:
                        l = next(data) 
                        if "props:" in l:
                            break
                        mode, refresh, *_ = l.split()
                        connectors[name]['modes'].add((mode, int(refresh)))
                        mode_list.append(Mode(name, mode, int(refresh)))
    return connectors, mode_list


if __name__ == '__main__':
    data = call_modetest()
    connectors, modes = parse_modetest(iter(data.splitlines()))
    best_modes = sorted(modes, key=sort_modes)
    pp.pprint(best_modes)
    print("Best Mode:", best_modes[-1])