CreateDate vs CreationDate

[ejm554]

Hello. I'm an ExifTool and metadata newbie, and I'm trying to understand why there are two Quicktime date tags that have nearly identical names, and how exactly they are different.

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exiftool -creat*date -G 20180731T190001.IMG_2776.0.0.MOV
[QuickTime]     Create Date                     : 2018:08:01 00:00:01
[QuickTime]     Creation Date                   : 2018:07:31 19:00:01-05:00


My search online and on this forum has not turned up a clear answer, except that one of them might use UTC and the other reflects the time zone of a device (the camera?). I'm hoping for more background and other details. Can anyone provide? :-)

I also noticed that ExifTool might consider the CreateDate tag more important in some way given that it is returned when using the -alldates shortcut, where the other tag is not. Is it preferred for some reason?

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exiftool -alldates -G 20180731T190001.IMG_2776.0.0.MOV
[QuickTime]     Create Date                     : 2018:08:01 00:00:01
[QuickTime]     Modify Date                     : 2018:08:01 00:08:32


The renaming program that was used to add a timestamp to my filename apparently uses non-UTC create/creation metadata, which in this file's case, indicates a different day. This hasn't been a problem (yet), but perhaps I should consider adopting a better standard. Any opinions on that would also be welcome!

[Phil Harvey]

CreateDate is part of the movie header.  CreationDate is part of the metadata proper.  The fact that these differ by the time zone indicates that you should be using the -api QuickTimeUTC option, because they (presumably) should be the same.

The AllDates shortcut is really for EXIF date/time tags, but yes, I would give CreateDate priority although there is the problem of whether or not it is stored properly in UTC as per the QuickTime specification.

- Phil

BTW, you look a lot like Bruce Willis

[ejm554]

Thank you. Can you direct me to some (newbie-friendly) documentation on how to use/set the -api QuickTimeUTC option? I assume this is something that is available somewhere on the ExifTool site, but I cannot seem to locate it. 

P.S. Bruce was one of the available avatars, and since he (coincidently) looks exactly like me, I chose that option.

[Phil Harvey]

Here is how to use this option with the first command you mentioned:

exiftool -api QuickTimeUTC -creat*date -G 20180731T190001.IMG_2776.0.0.MOV

- Phil