"Re-add" or rescan photos to make use of EXIF data

RoyalBlue · October 19, 2022, 8:15pm

I have uploaded several tens of GBs of photos onto my NextCloud server. The Photos app, as well as the Files app show the photos not rotated according to EXIF data, but some are 90deg off.

I noticed today that I was missing PHP exif-extension, so I installed it. Now when I upload new photos, the EXIF data is properly read and the photos show up in correct rotation.

BUT: is there a possibility to re-scan the photos somehow to make EXIF data effective for the photos which are already on the server? Or do I really need to re-upload them all to have the EXIF scanned?

I tried already

occ files:scan-app-data
occ files:scan

but these did not have any effect for the photo orientation.

just · October 19, 2022, 9:02pm

You can install photoprism and use that to organize your photos. It includes support for Nextcloud. My understanding is that exif support is still in development in nc photos.

flow-axel · October 20, 2022, 7:35am

Thanks @just for the Photoprism hint. Just playing around with it a bit. How does it support Nextcloud?

I usually run Lychee on my Nextclouds as a public frontend for picture and video website for partners and customers. Lychee just imports the original nextcloud files as a folder synch and does not store the pictures or videos on its own then, just a few little previews.

Photoprism cannot read my “Library”. Is there a deeper nextcloud integration or am I missing some rights/setup details?

artonge · October 20, 2022, 11:51am

Hello @RoyalBlue,

The possibility to re-scan for metadata, and therefore EXIF data, is already merged for v26, and is pending merge for the next minor of v25.

github.com/nextcloud/server

Extract GPS data from EXIF

nextcloud:master ← nextcloud:feat/extract_gps_from_exif

opened 05:29PM - 11 Aug 22 UTC

artonge

+170 -39

I had to do a workaround to read EXIF data properly: ~~Some work has been don…e by @CarlSchwan [here](https://github.com/nextcloud/server/pull/31839/files#diff-696d573a441e273811747c682474b6b94c726470441f35092a30824bdb7553f9R18).~~ ~~But the `exif_read_data` call does not work, and probably never worked. One possible explanation is that the resource is wrapped. From [the README](https://github.com/icewind1991/streams):~~ ~~> Note: due to php's internal stream buffering the $count passed to the read callback will be equal to php's internal buffer size (8192 on default) an not the number of bytes requested by fopen()~~ ~~As it works when the stream is not wrapped, it might be an explanation for why the `exif_read_data` call fails.~~ ~~To make it work, I copy the stream into a tmp stream without wrappers before passing it to exif_read_data.~~ :heavy_check_mark: I found a workaround by calling `stream_set_chunk_size($fileDescriptor, 1);` before we read the stream. No idea why it works, but it does, and I am reverting it right after to prevent any side effect outside our use case. I also cherry-picked @CarlSchwan PR that adds a CLI command to extract metadata https://github.com/nextcloud/server/pull/32309

RoyalBlue · October 20, 2022, 4:43pm

Awesome news, @artonge! I’ll wait for the release then.

just · October 20, 2022, 5:29pm

Try reading photoprism documentation and making some basic internet searches. This should get you started:

flow-axel · October 20, 2022, 5:44pm

Thanks for the hint @just !
I abandoned Dav a bit, since it is not really usable on Windows machines when the files are bigger than 4GB. I mostly have bigger files here, ie clips with 600Mbit. Once they are on the nextcloud, it is easy to synch them into Lychee.

I also use the Lychee web interface to hand over those files to partners, clients and other professional productions. It simply looks more beautiful and is super nice to operate and hell fast. You can import a local folder (ie /var/www/nextcloud/data/axel/files/Photos) super quick and I do not have to play around with any folder or file rights, nor with the owner (www-data). It also does not need a docker and runs in parallel to Nextcloud on the same Apache2. Simple and beautiful

Still, I will try the PhotoPrism a bit, seems to have some nice features.

just · October 20, 2022, 5:45pm

Nextcloud is webdav

flow-axel · October 20, 2022, 5:49pm

@just I know. But I only handle the Windows<>NC part with it.

If I use DAV for the production storages, it simply fails in Windows.

https://www.google.com/search?q=windows+10+webdav+file+size+limit&oq=windows+10+webdav+file+size+limit&aqs=chrome..69i57.10648j0j7&sourceid=chrome&ie=UTF-8

RoyalBlue · November 3, 2022, 9:43pm

Just tried the rescan and no photos were rotated on rescan, as their rotation is still wrong when viewing in Photos app.

# sudo -u wwwrun php occ files:scan --generate-metadata --all
Starting scan for user 1 out of 3 (xxxxx)
Starting scan for user 2 out of 3 (yyyyy)
Starting scan for user 3 out of 3 (zzzzzz)

+---------+-------+--------------+
| Folders | Files | Elapsed time |
+---------+-------+--------------+
| 91      | 5261  | 00:26:25     |
+---------+-------+--------------+

Looking back at the commit [stable25] Extract GPS data from EXIF by backportbot-nextcloud · Pull Request #34535 · nextcloud/server · GitHub

To me it seems ExifProvider.php only handles GPS and image size, not the rotation. So was there even a possibility of the rotation via re-scanning to work to begin with?

RoyalBlue · November 7, 2022, 6:21pm

Alright, so all in all, figured this out.

It boiled down to not be an actual EXIF data issue, but actually about the previews. I did not have PHP EXIF-module installed when first uploading the photos, so the preview generation did not rotate the images properly.

What I needed to do eventually was this:

stop Apache2
remove /appdata_*/preview/ folder (just the preview!)
run: occ files:scan-app-data
start Apache2
(Clear the browser cache of my Nextcloud site data)

Now my preview images are in correct rotation.

(Although configured for too big size as default, so need to modify the config and run again, maybe. Or try the Previewgenerator app)