Understanding and improving Nextcloud Previews

🏷️ General
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Hi, I have been playing with the preview generation process to try to speed up things for low end devices (mainly for NextCloudPi)

In case you are interested I would love some feedback

https://ownyourbits.com/2019/06/29/understanding-and-improving-nextcloud-previews/

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Thank for sharing your results, it’s really interesting and not only for RPi-users.

I suppose it is not possible to use the raw image when using the max-preview? And only do it for some sort of camera RAW formats that are not directly supported by browsers.

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Very interesting! I didn’t know that my preview folder took up over 160GiB until I checked it because of your article.

I would’ve liked to see a comparison of disk usage from your sample data between the default config and your optimized config of the preview generator. Because I don’t really mind the cpu time.

Still an excellent article with obviously a lot of work put into it and a lot of insights given to the reader! Thanks again for that

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Thanks @tflidd I assume that the max image is there in case the picture is really big, for instance 20MiB. In that case it would be a waste to send 20MiB to the browser.

That being said, when it’s a reasonable size we could save space by using that one directly, instead of storing an identical copy in the previews folder…

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Just wanted to share my experience with nachoparker’s suggested settings

default:

  • runtime: 1d 05:00:13
  • size: 163,32 GiB

optimized settings:

  • runtime: 08:43:50 (single threaded, jpg quality 90)
  • size: 32,95 GiB

In my particular case I save 69,90% cpu time and 79,82% of space with the optimized settings, which i find pretty neat. I can also confirm, that image quality looks nice, as far as i have seen it.

My findings for the default and optimized run are not 100 % comparable because they were done on a production system, but i think they should be good enough. Neither was the cpu blocked by any other process, nor were there major changes to the file system.

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The link now point to a disabled page. :sob:
@nachoparker, is there a way to get back the article ?
This is a great article !

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I am working with my hosting provider to sort out the issue. They were pretty crappy honestly.

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the problem is now solved

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@nachoparker I have made a post regarding the jpeg_quality showing that Nextcloud internal preview generation does not use the same setting as previewgenerator for jpeg_quality. Would you care to comment on that?

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website is down again. Any forum where you’ve put it on?

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Ownyourbits is deader than dead for sometime now. Here you go:

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