Fix wrong Gopro Hero7 2016 media timestamps from correct JPEG GPS metadata timestamps

gopro2016.py

"""
Read timestamps of jpegs from given or current directory.
If there are files with creation year 2016 
and if the difference between creation date and gps date is the same for all those files
then fix metadata dates and file dates of all 2016 media files (not just the jpegs)
"""

TZ = 2*60  # desired difference in minutes between GPS (UTC) and TZ to use within media files

from subprocess import check_output
from datetime import datetime, timedelta
from sys import argv
from os import utime
from statistics import fmean

import json

def diff(cr, gd, gt):
    created = datetime(int(cr[0:4]), int(cr[5:7]), int(cr[8:10]), int(cr[11:13]), int(cr[14:16]), int(cr[17:19]))
    gps = datetime(int(gd[0:4]), int(gd[5:7]), int(gd[8:10]), int(gt[0:2]), int(gt[3:5]), int(gt[6:8]))
    return timedelta.total_seconds(gps - created)

if len(argv) == 2:
    dir = argv[1]
else:
    dir = '.'

cmd = 'exiftool -j -CreateDate -GpsDateStamp -GpsTimeStamp -ext jpg'.split()
cmd.append(dir)
pics = json.loads(check_output(cmd))
pics = [{'file': pic['SourceFile'], 'diff': diff(pic['CreateDate'], pic['GPSDateStamp'], pic['GPSTimeStamp'])} for pic in pics if pic['CreateDate'].startswith('2016:') and 'GPSDateStamp' in pic]
if len(pics) == 0:
    print(f'No 2016 jpegs found in {dir}')
    exit
    
dmin = int(min([pic['diff'] for pic in pics]))
dmax = int(max([pic['diff'] for pic in pics]))
davg = round(fmean([pic['diff'] for pic in pics]))
if davg != dmax and davg != dmin:
    print(f'multiple time differences found: min={dmin}, avg={davg}, max={dmax}')
    exit

cmd = 'exiftool -j -CreateDate'.split()
cmd.append(dir)
meds = json.loads(check_output(cmd))
print(meds)
meds = [{'file': med['SourceFile'], 'date': med['CreateDate']} for med in meds if 'CreateDate' in med and med['CreateDate'].startswith('2016:')]

for med in meds:
    cr = med['date']
    created = datetime(int(cr[0:4]), int(cr[5:7]), int(cr[8:10]), int(cr[11:13]), int(cr[14:16]), int(cr[17:19]))
    fixed = created + timedelta(seconds=davg + TZ*60)
    fixed_str = fixed.strftime('%Y:%m:%d %H:%M:%S')
    cmd = ['exiftool', f'-time:all="{fixed_str}"', '-wm', 'w']
    cmd.append(med['file'])
    result = check_output(cmd).decode()
    fixed_ts = fixed.timestamp()
    utime(med['file'], times=(fixed_ts, fixed_ts))
    print(med['file'], result)

fixes wrong timestamps in media files recorded after low battery situations

tested with python 3.11 and exiftool 12.89

limits:

• all 2016 files in the directory are recorded after the same battery failure (i.e. all have the same time offset)
• all files in the directory use the same timezone and DST offset (as given in TZ constant)
• exiftool makes backups of the changed media files in the same directory. Plan for the extra space requirements.

if needed split the files up in different directories to match these requirements.

Times in media metadata should all be UTC, but Gopro seems to use local time. If you want UTC just set TZ=0

why doesn't Gopro use GPS time to set camera time after battery outage although they use it in JPEG metadata :/

posted about it at https://community.gopro.com/s/profile/005Uv0000026pJd and https://exiftool.org/forum/index.php?topic=16254.0

not all JPEGs of the gopro seem to get GPS timestamps -> changed script to only use those that got it.
(used on caba1)