[KPhotoAlbum] Auxiliary files, again

[Robert Krawitz]

I want to re(re)visit the idea of storing auxiliary non-image photos
in the kpa database alongside of images.

My use case is that I use darktable and/or rawtherapee to process
photos.  Those package generate sidecar files (.xmp and .pp3
respectively) containing information about the editing steps.

One thing I do a lot is crop and rotate photos.  That comes from
shooting 2000+ frames and using 300-400 of them from basketball and
football games.  I rarely do any other processing on them.  I wrote a
script this year to extract the crop and rotation information from the
sidecar files and use convert (from ImageMagick) to perform the crop
and rotation steps, in addition to applying a watermark; this
parallelizes very nicely and I can process 300 images in about a
minute (vs. 10-15 minutes using the UI).

I want to save my edits, of course; I want to be able to regenerate
the edited photo later for something.  But I don't want to store
another large JPEG file; the sidecar file is both (much) more compact
and more useful; I may want to generate a version without a watermark,
for instance.

What I'd like to do is stack auxiliary, non-image files with real
images, using autostack rules like the existing ones for autostacking
imags.  This sounds straightforward enough, but I can think of
difficulties:

* If a stack is broken by having one or more of its images removed,
  what happens to the auxiliary files?  Do they automatically stay
  stacked with one or another of the images, do they get dropped, or
  what?

* Checksums may not be sufficient to distinguish between auxiliary
  files.  The odds against two auxiliary files having identical
  contact might not be that high, particularly if the filename is not
  stored in the auxiliary file.

I'm sure there are other issues I haven't reached yet, but
nevertheless, this kind of functionality would be extremely useful.
-- 
Robert Krawitz                                     <rlk at alum.mit.edu>

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