Preview size

[pulsejet]

Currently the preview size is fixed to 1024 unlike viewer, which is responsive

[keesfluitman]

preview sizes of the "thumbnails" in your timeline are quite weird as well. Just a list of what came up out of a 100 or so requests.
278x278
310x310
339x339
340x340
344x344
395x395
454x454
why can't all be the same? most were 340x340 though. sometimes a lot of 339

[pulsejet]

That seems correct. The timeline needs to load lower-res thumbs to be performant. But the boundaries at which these exist aren't necessarily the same.

[keesfluitman]

yes. But why so many different sized ones? If I use preview generator to generate 340x340 for all my photos, would it then only use them?

[pulsejet]

Yes. This is a workaround for some weirdness in Nextcloud behavior. The sizes of the returned images match the pre-generated ones.

[keesfluitman]

It's maybe not totally part of this "bug". But I still struggle to find a proper way to pre-generate previews. Mostly because my users have different phones, browsers, etc. For instance I pre-generated, then tested with firefox. Firefox-Memories requests 383... I have 340 generated... So all in all the preview folder is getting bigger and bigger. This does not only concern you of course.

[pulsejet]

It's maybe not totally part of this "bug". But I still struggle to find a proper way to pre-generate previews. Mostly because my users have different phones, browsers, etc. For instance I pre-generated, then tested with firefox. Firefox-Memories requests 383... I have 340 generated... So all in all the preview folder is getting bigger and bigger. This does not only concern you of course.

I assume you're using preview generator to pre-generate.

Nextcloud uses a power-of-2 scheme to serve previews. So when e.g. memories requests 383, the returned preview is not necessarily 383 but whatever is the closest. So this has nothing to do with the preview folder getting bigger, since the sizes of the previews are pre-determined.

[pulsejet]

As an example: the size of the requested and returned images aren't the same:

[rhatguy]

When this is implemented it would be great to get a bit of detail around the recommended configuration (along with the preview generator app) for most people. I've struggled with preview sizes in Nextcloud for years. :(

[keesfluitman]

When this is implemented it would be great to get a bit of detail around the recommended configuration (along with the preview generator app) for most people. I've struggled with preview sizes in Nextcloud for years. :( <

I think this is the best way to set previews. You will have 3 and no more will be created. Memories doesn't request the max version yet though. That kind off annoys me still. It still requests a smaller version. (1024x1024) That's why I won't use memories yet. Since it's max quality is bad and it takes more preview space.

occ config:app:set previewgenerator squareSizes --value="32 256"
occ config:app:set previewgenerator widthSizes --value="256 384"
occ config:app:set previewgenerator heightSizes --value="256"
occ config:system:set preview_max_x --value 2048
occ config:system:set preview_max_y --value 2048
occ config:system:set jpeg_quality --value 60
occ config:app:set preview jpeg_quality --value="60"

I currently have
Total occupied space: 16.8 GB
in 198,490 folders and 155,951 files
for about 30k pictures.

http://web.archive.org/web/20200513043150/https://ownyourbits.com/2019/06/29/understanding-and-improving-nextcloud-previews/

@pulsejet Could you set it to request the max preview (or the original, maybe by a button or config option) at any time for the normal picture? Viewer also requests the max and this way we'd only need 3 types of preview files and have more control over it. (but i'd prefer that anytime I click a picture I get the original. Since I have 10gbit internet, that's fast enough)

Sorry for all the edits:
I must say, although it's so beautiful to have it all integrated. Apps like Pigallery, Photoprism and Photoview do it so much more efficient and clear. Nextcloud has a clear performance issue when a lot of requests are done. And it hurts the server.

I think this boils down to an architectural design choice, which has been at debate in a Github Request and explained here:
http://web.archive.org/web/20200513040858/https://ownyourbits.com/2019/10/16/a-new-architecture-for-nextcloud/

I sometimes consider going back to Owncloud, just for basic cloud functions, and using external apps for other functions. But I'll give it a bit of time :).

[pulsejet]

@keesfluitman this fix is on the roadmap for v4.9

I must say, although it's so beautiful to have it all integrated. Apps like Pigallery, Photoprism and Photoview do it so much more efficient and clear. Nextcloud has a clear performance issue when a lot of requests are done. And it hurts the server.

I'm surprised you've performance issues. I've a similar number of files (~100000) and ~25k photos totaling 100GB and Nextcloud is very fast for me (and I don't run particularly fast hardware, just a Pentium). I used to work with another setup with ~20k users and that had no performance issues either.

BTW a JPEG quality of 60 isn't the most optimal IMO. Seems too low.

[pulsejet]

I think this boils down to an architectural design choice, which has been at debate in a Github Request and explained here: http://web.archive.org/web/20200513040858/https://ownyourbits.com/2019/10/16/a-new-architecture-for-nextcloud/

Btw some of this isn't so valid anymore. With PHP 8 JIT and PHP-FPM + nginx, you don't need to warm up everything for every request; instead there's a thread pool of workers. And PHP got very fast in the last couple of years. If you're running (say) 7.4 with Apache I do expect it'll be much slower.

[keesfluitman]

@keesfluitman this fix is on the roadmap for v4.9

I must say, although it's so beautiful to have it all integrated. Apps like Pigallery, Photoprism and Photoview do it so much more efficient and clear. Nextcloud has a clear performance issue when a lot of requests are done. And it hurts the server.

I'm surprised you've performance issues. I've a similar number of files (~100000) and ~25k photos totaling 100GB and Nextcloud is very fast for me (and I don't run particularly fast hardware, just a Pentium). I used to work with another setup with ~20k users and that had no performance issues either.

BTW a JPEG quality of 60 isn't the most optimal IMO. Seems too low.

It isn't that slow of course. But it's a bit inefficient. I find the other apps have more options (loading of originals), less preview files and faster respond times. I sometimes see nextcloud not requesting previews, not loading the previews faster than when I would on the fly load them. It just seems a bit buggy. Do you have a place where I can learn a bit about how it works (the php 8 JIT, PHP-FPM and nginx? Im trying to learn a bit as well.

Don't know about the jpeg quality. It seems fine atm. Im no expert on that. I just followed the guide on that.

[pulsejet]

Do you have a place where I can learn a bit about how it works (the php 8 JIT, PHP-FPM and nginx? Im trying to learn a bit as well.

I just trust good old Google for these things. There are many nice blogs where people have analyzed this in great detail.