[KPhotoAlbum] Saving information into exiv

[Robert Krawitz]

On Tue, 20 Aug 2019 19:20:13 -0400, Joe wrote:
> KPA writes almost everything it does into its database leaving the
> actual pictures untouched.
>
> I'm not sure how the indexing gets done. One of the experts will
> probably clarify that.

There are two indices:

1) The EXIF data known to KPhotoAlbum is stored in an SQLite3 database
   (exif_info.db) in the root of the images tree.

2) All other information -- tags, relationships between tags, MD5
   checksums, and also the date, width, and height (for efficiency) is
   stored in index.xml in the root of the images tree.  There may be a
   few other things there, such as geographical coordinates (I don't
   use that, and I don't recall offhand).

In addition, thumbnails are stored in packed bitmap form, with bitmaps
packed into 32 MB chunks, in the .thumbnails directory, with
.thumbnails/thumbnail_index mapping from image filename to location of
the image.  The packed bitmap form is for efficiency (fewer filesystem
accesses).  Video thumbnails are stored (not packed) in
.videoThumbnails in the root.

The core app does not that I'm aware of ever modify the images.  Some
plugins might, which of course would invalidate the MD5 checksum.
This is a core design principle.  Were it not for the fact that the
index files are stored in the image root, it would be possible to have
full functionality in a read-only image tree.

> On 8/20/19 6:55 PM, Joan wrote:
>> I am using kphotoalbum to manage my collection that was totally
>> anarchic (folders with names, lots of folders pending to catalog)
>> I changed the structure to yyyy/month and now it seems that all the
>> photos are being reread. My question would be:
>>
>>   * Does kphotoalbum save its info to exiv? Can I be done somehow?
>>   * Will the same photo in a different location in drive preserve the
>>     attibutes I tagged?
>>
>> I only saw some discussion about info being written to exiv by the
>> coordinates plugin, but I couldn't find anything about the rest of the
>> attributes.
-- 
Robert Krawitz                                     <rlk at alum.mit.edu>

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