[GTALUG] Python and/or Video help please

31 Oct 2016

      A month ago I had problems, after an Ubuntu upgrade, getting my screen 
resolution above 1024x768.

In this forum I was given a link to the script below to fix the problem 
and it did! Joy.

Now I tried to run a video and the screen went back to unknown and set 
to 1024x768 :(

I ran the script again, and I get the following result:

stephen@avalon:~/scripts$ ./get-edid.py VGA-1
Traceback (most recent call last):
   File "./get-edid.py", line 65, in <module>
     edid_bin = get_edid_for_connector(connector_name)
   File "./get-edid.py", line 51, in get_edid_for_connector
     edid_str = slurp_edid_string(i)
   File "./get-edid.py", line 39, in slurp_edid_string
     assert re.match(r'\tEDID:', output_lines[line_num+1])
AssertionError

I do not know anything about Python. Can someone help me figure this out?

Many thanks

Script
#!/usr/bin/env python

import binascii
import re
import subprocess
import sys
from os.path import basename

XRANDR_BIN = 'xrandr'

# re.RegexObject: expected format of xrandr's EDID ascii representation
EDID_DATA_PATTERN = re.compile(r'^\t\t[0-9a-f]{32}$')

def get_edid_for_connector(connector_name):
     """Finds the EDID for the given connector.
     Args:
         connector_name (str): Name of a connector, i.e. HDMI-0, DP-1
     Returns:
         Binary EDID for the connector, or None if not found.
     Raises:
         OSError: Failed to run xrandr.
     """

     # re.RegexObject: pattern for this connector's xrandr --props section
     connector_pattern = re.compile('^{} connected'.format(connector_name))

     try:
         xrandr_output = subprocess.check_output([XRANDR_BIN, '--props'])
     except OSError as e:
         sys.stderr.write('Failed to run {}\n'.format(XRANDR_BIN))
         raise e

     output_lines = xrandr_output.decode('ascii').split('\n')

     def slurp_edid_string(line_num):
         """Helper for getting the EDID from a line match in xrandr 
output."""
         edid = ''
         assert re.match(r'\tEDID:', output_lines[line_num+1])
         for i in range(line_num + 2, len(output_lines)):
             line = output_lines[i]
             if EDID_DATA_PATTERN.match(line):
                 edid += line.strip()
             else:
                 break
         return edid if len(edid) > 0 else None

     for i in range(len(output_lines)):
         connector_match = connector_pattern.match(output_lines[i])
         if connector_match:
             edid_str = slurp_edid_string(i)
             if edid_str is None:
                 return None
             return binascii.unhexlify(edid_str)

     return None

if __name__ == '__main__':
     if len(sys.argv) != 2:
         sys.exit('Usage: {} <OUTPUT>'.format(basename(sys.argv[0])))

     connector_name = sys.argv[1]

     edid_bin = get_edid_for_connector(connector_name)
     if edid_bin is None:
         sys.exit('No EDID found for output {}'.format(connector_name))

     if sys.version_info >= (3, 0):
         sys.stdout.buffer.write(edid_bin)
     else:
         sys.stdout.write(edid_bin)

sys.exit(0)

-- 
Stephen