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Permlink Replies: 4 - Pages: 1 - Last Post: 27 Jun 22, 23:46 Last Post By: davidekholm Threads: [ Previous | Next ]
justinhow

Posts: 56
Registered: 3-Apr-2020
Updating EXIF/XMP metadata does not change file modified data
Posted: 23 Jun 22, 20:28
 
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I have noticed that when I update comments (for example) on a photo the XMP/EXIF data is written to the jpg file (as per my jAlbum settings) but the file modified date does not change (Windows).
Is this by design as it makes tracking changes at the file level more challenging?

Edited by: justinhow on 23 Jun 2022, 19:32
JeffTucker

Posts: 8,256
Registered: 31-Jan-2006
Re: Updating EXIF/XMP metadata does not change file modified data
Posted: 25 Jun 22, 13:16   in response to: justinhow in response to: justinhow
 
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Just a guess, but if the file modified date were changed, then the next time you made the album, jAlbum would think that the file had been changed since the previous build, and would reprocess it. Then it would write out the metadata again, and touch the file date again.

In short, it would reprocess the images every time you made the album!
justinhow

Posts: 56
Registered: 3-Apr-2020
Re: Updating EXIF/XMP metadata does not change file modified data
Posted: 25 Jun 22, 13:35   in response to: JeffTucker in response to: JeffTucker
 
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I don't quite understand what you mean. I am suggesting that the jpg modfied date is changed when the image comment/title etc is changed through jAlbum. It already updates the image with the EXIF/XMP updates from this change to title/comment and this happens at the edit time, not the album creation time.
I can't see why this would update everytime the album is created as this EXIF data is not written out to jpg's everytime the album is re-created but but only when individual photos have changes made to them.
JeffTucker

Posts: 8,256
Registered: 31-Jan-2006
Re: Updating EXIF/XMP metadata does not change file modified data
Posted: 25 Jun 22, 14:00   in response to: justinhow in response to: justinhow
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I'm probably just remembering the way it worked in a much earlier version of jAlbum.

In that case, I suspect that the Java routine that writes out the metadata doesn't automatically touch the file date, and David decided not to bother doing it explicitly.

FWIW, it behaves the same way in macOS.
davidekholm

Posts: 4,100
Registered: 18-Oct-2002
Re: Updating EXIF/XMP metadata does not change file modified data
Posted: 27 Jun 22, 23:46   in response to: justinhow in response to: justinhow
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jAlbum avoids updating the last modified date to the source images when you simply change XMP metadata. The reason for this is that jAlbum uses the last modified date to determine whether to reprocess the image or not. jAlbum tries to avoid reprocessing images during "make album" operations to save time.
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