extracting subsecond times from iphone video .MOV - multiphone syncro.

[robm]

What a tool!
I'm trying to extract the EXACT time (of first frame or ?) from .MOV files taken of the same event from multiple iphones.  I can get the seconds just fine but can't get either the raw timestamp, or millis.

exiftool -a -n -SubsecTime -ee IMG_4027.MOV
returns nothing, neither does 'Digitized' or 'Original', so can I then assume those tags don't exist in the file?

exiftool -a -n -ee  IMG_4027.MOV

dumps lots of data, but all times are formatted to your default and show

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Track Create Date               : 2024:07:31 19:43:26
and I've tried all the -d options

Does anybody know if iphone stores a timestamp in the Exif that is ms resolution and how to extract it?  I can't believe that Apple is storing a formatted string rather than a timestamp with ms precision, in fact I've found posts confirming that it's a timestamp.

Yes, I've googled everything I can think of, but it's a big internet!

Interestingly ChatGPT said to use exiftool:

exiftool -time:all -milli-seconds  IMG_4027.MOV

but that didn't work either it returned

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exiftool -time:all -milli-seconds  IMG_4027.MOV
File Modification Date/Time     : 2024:07:31 15:43:26-04:00
File Access Date/Time           : 2024:07:31 15:44:29-04:00
File Inode Change Date/Time     : 2024:07:31 15:45:13-04:00
Create Date                     : 2024:07:31 19:43:26
Modify Date                     : 2024:07:31 19:43:34
Track Create Date               : 2024:07:31 19:43:26
Track Modify Date               : 2024:07:31 19:43:34
Media Create Date               : 2024:07:31 19:43:26
Media Modify Date               : 2024:07:31 19:43:34
Creation Date                   : 2024:07:31 15:43:26-04:00

fyi, after taking the video, I stored it in 'files' on the iphone then accessed in on my Mac using 'finder' in the 'icloud' directory which is automatically copied to

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/Users/user/Library/Mobile Documents/com~apple~CloudDocs/Downloads

Any thoughts appreciated.

Rob
ps. if you think the times are wonky, some are UTC, some are EDT I believe.

[StarGeek]

Most video time stamps cannot include subseconds (or a time zone). The Quicktime:CreationDate and Quicktime:DateTimeOriginal can include it (or at least exiftool allows you to write it) but I don't think I've ever seen a video with subseconds included in those tags

Interestingly ChatGPT said to use exiftool:

exiftool -time:all -milli-seconds  IMG_4027.MOV

ChatGPT lied to you There's no such thing as a "milli-seconds" tag. But it was on the right track

What you want to do is include the -Time:all part and add that to the command in FAQ #3
exiftool -time:all -G1 -a -s file.mov

That will show you all the time related tags in the file

ps. if you think the times are wonky, some are UTC, some are EDT I believe.

Yes, most of the video time stamps are UTC, except for the two I first mentioned. The file ones are Local time of the computer adjusted from UTC. The "Creation Date" (Quicktime:CreationDate) would be local time where the video was shot, which may be different from the file system ones. For example, if you had shot the video in Paris and then returned home to your EDT time zone, then the Quicktime:CreationDate would show that time and time zone, but the file system ones would show a different time.

Make sure you are running exiftool on an unedited file. Hopefully, there will be some EXIF tags in the file, but any editing of the file would removed those tags, as EXIF data is non-standard in a MOV file. But the output above does not appear to have any EXIF tags, only the Quicktime tags.