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When and why does MC alter a files "Modified Date" attribute?

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Negasonic:
I searched but only found this thread (where unfortunately no one replied): https://yabb.jriver.com/interact/index.php/topic,73149.msg495886.html#msg495886


Two specific examples where MC is modifying "Date modified" in a file that I would like to know why it happens and if there is a way to avoid it?

1. Music Files and changing folder.jpg

1. In Windows Explorer I open a folder which consists of 10 flac files and a Folder.jpg file. I then exchange the Folder.jpg for a new, improved Folder.jpg. I do nothing with the flac files. Modified date for the flac files remain the same, as it should be.

2. I then tab into MC and right click the album and choose "Quck Find in File/Cover Art Directory" and MC promptly updates the view with the new Folder.jpg

3. Tabbing back to Windows Explorer, I now see that all the individual flac files have a new Modified Date. I understand the library/data base gets updated, but what did MC modify in the actual flac files in this case?


2. Image Files (Screenshots)

For awhile I've been thinking about using MC for images and decided to do a test with a couple of screenshots (taken through Steam) from a couple of different games.

This happens:

1. The image in this example is named 238260_20171118181435_1.jpg  (This is how Steam names the files, first a code for the specific game title followed by the full date and time it was taken. The 1 in the end I dont know about)
In the preview pane of Windows Explorer it displays "Date modified: 2017-11-18 18:14" which is the date this image was taken/screenshotted. (same as file name minus the seconds)

2. I drag the file to a new folder on the same HD which will serve as a test folder for MC and Images. Date modified remains unchanged after the move.

3. In MC I run import and as soon as the import is done Date modified in Windows Explorer is changed to the current date and time.
There are now no traces left in the file itself or MC of the original date and time that shows when this image was "taken" (screenshot) except (in this particular case) in the file name.

The [Date] tag inside MC is filled with the new, current date and time. So the original "Date modified" gets modified by MC during import. Why is that?

Hoping for some feedback.

MusicHawk:
I've found this frustrating too, in image and audio files. Modified gets changed for reasons that do not match up with me explicitly modifying the file. I don't know the answer. But, some possible factors that might give you ideas:

Windows usually changes a physical (for lack of a better word) file's Date Modified when it gets rewritten to the disc, whatever the reason for the change, which could be tiny or trivial.

In some (probably many) circumstances, when an MC database/library tag/field is changed, MC writes that change to the physical file too.

MC also updates the database/library upon certain implicit actions, such as "playing" a file (not clear if viewing a photo is "playing" it). Apparently MC stores info such as number of times played, last time played, etc, data I have no need for, wish there was a way to turn this off. Again such library changes might get written to the physical file, thereby modifying it.

And in some situations MC does other actions (look up cover art, send cover art change to server, analyze audio) that are mostly not announced, they just happen, but some change the library and thereby might trigger a physical file update too. And others directly modify the physical file.

My "complaint" (soft grumble) is that whenever MC does physical file changes that are not desired or helpful to me, it triggers my backup system to copy the file again..and again...and again. I wish for a switch or check boxes to specify what data goes in the physical file, or not.

Having explicit file tags control should be matched with a way to monitor it, or even to audit (compare database and physical tags of selected records/files). This might solve the problem of image/photo tags not being automatically saved to photos (large photos, mainly). Getting past this requires doing manual Update Tags (from Library). But since I don't always notice the original update failure I have to do a mass manual Update of all the photos I've been working on, which then triggers more backup activity. Ugh.

glynor:

--- Quote from: MusicHawk on May 07, 2018, 02:01:14 pm ---Windows usually changes a physical (for lack of a better word) file's Date Modified when it gets rewritten to the disc, whatever the reason for the change, which could be tiny or trivial.

--- End quote ---

Yes. That's how the filesystem works. It doesn't care about the "bucket of bits" only the last time that file was written.


--- Quote from: MusicHawk on May 07, 2018, 02:01:14 pm ---MC also updates the database/library upon certain implicit actions, such as "playing" a file (not clear if viewing a photo is "playing" it). Apparently MC stores info such as number of times played, last time played, etc, data I have no need for, wish there was a way to turn this off. Again such library changes might get written to the physical file, thereby modifying it.

And in some situations MC does other actions (look up cover art, send cover art change to server, analyze audio) that are mostly not announced, they just happen, but some change the library and thereby might trigger a physical file update too. And others directly modify the physical file.

My "complaint" (soft grumble) is that whenever MC does physical file changes that are not desired or helpful to me, it triggers my backup system to copy the file again..and again...and again. I wish for a switch or check boxes to specify what data goes in the physical file, or not.

--- End quote ---

MC stores these changes in the Library (the database) which has no impact on the files on disk. However, MC does also write many fields to the tags in the files, which will touch the file on disk.

However, MC does have exactly the switch you want, on a field-by-field basis, and you can turn this off. Each field in MC has a value in Manage Library Fields called Save in file tags (when possible). Turn this off, and then MC won't update the files on disk when this field changes.

Or, if you prefer, you can globally disable all writing to file tags:
https://wiki.jriver.com/index.php/Update_Tags_When_File_Info_Changes

Negasonic:

--- Quote from: MusicHawk on May 07, 2018, 02:01:14 pm ---
My "complaint" (soft grumble) is that whenever MC does physical file changes that are not desired or helpful to me, it triggers my backup system to copy the file again..and again...and again.


--- End quote ---

Yesss... this is what prompted me to ask the question. For awhile now, I've been changing the cover art, folder.jpg image, for albums and been wondering during backup of the files why I need to re-backup all the music files when all I did was replacing the cover art image. I never modified the actual music files. Or so I thought.


I only had these fields in MC set to "Save in file tags (when possible)":
Album
Album Artist
Name
Date

Testing:

1. Turning "Update tags when file info changes" OFF seems to leave the music files untouched in this case (swapping the folder.jpg for a new one).

2. Turning "Update tags when file info changes" ON and deselecting "Save in file tags..." in all of the above fields also seems to leave the music files untouched.
EDIT: I did some more testing with this and it doesn't seem to work. Even with every single Field (including hidden ones) having "Save in file tags..." deselected, all of the music files will still have their "Date modified" updated to the time when I use "Quick Find in File/Cover Art Directory" in MC. Just from swapping the folder.jpg image to a new one.

3. Turning "Update tags when file info changes" ON and selecting "Save in file tags..." in any of the above fields will modify the files, just by me changing the folder.jpg for a new one and clicking "Quick find in file..." in MC.
 
So, what is happening here in #2 and #3? Edit again: It may be related to the "Quick Find in File/Cover Art Directory" action. Skipping this and doing a regular import instead, did not alter "Date modified". If it is related to "Quick Find in File...", what happens during this process that modifies the files?

MusicHawk:

--- Quote from: glynor on May 07, 2018, 03:01:27 pm ---MC does have exactly the switch you want, on a field-by-field basis, and you can turn this off. Each field in MC has a value in Manage Library Fields called Save in file tags (when possible). Turn this off, and then MC won't update the files on disk when this field changes.
--- End quote ---

Thank you of reminding me of this. I have used it for my many custom fields, forgot that it also works with default fields. I've been using MC since MJ 5, and at some point thought there were built-in fields with behavior that could not be modified. Perhaps I've always been wrong about this, or maybe it changed over the years.

In any case, I agree with OP that sometimes I've seen Date Modified get changed for no obvious reason. Perhaps someone at JR can identify actions other than the controllable fields that write to the file (or do something else that causes Windows to update Data Modified). Or tell me I'm delusional (again<g>).

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