avif file compression size huge differences

[suntong]

Trying to build libvips from source myself, and running vips copy smart-crop.jpg smart-crop.avif using my own build executable, I'm getting:

$ ls -l smart-crop.*
-rw-r--r-- 1 root root 65955 Dec  2 03:18 smart-crop.avif
-rw-r--r-- 1 root root 79289 Dec  2 03:16 smart-crop.jpg

However, if running vips copy smart-crop.jpg smart-crop.avif using debian stable package executable, I'm getting:

$ ls -l smart-crop.*
-rw-r--r-- 1 root root 79289 Dec  1 23:02 smart-crop.jpg
-rw-r--r-- 1 root root 18533 Dec  1 23:02 smart-crop.avif

Why such huge differences in avif file compression size please?

PS. The smart-crop.jpg file is from https://raw.githubusercontent.com/h2non/imaginary/master/testdata/smart-crop.jpg

[jcupitt]

Hello again. I tried here and I see:

$ vips copy smart-crop.jpg x.avif
$ ls -l x.avif smart-crop.jpg 
-rw-rw-r-- 1 john john 79289 Nov 30 10:06 smart-crop.jpg
-rw-r--r-- 1 john john 18530 Dec  2 10:48 x.avif

That's with my own libvips, so I agree your build looks odd.

I had a quick look at your dockerfile:

• you are using a very old version of libheif, I would swap to something newer ... I'm on 1.16.2, but current is 1.17.5. That might be the cause of the difference
• you are building against imagemagick -- are you certain you need it? There are security implications if you are exposing this build to untrusted data
• you don't need gobject-introspection, gtk-doc-tools, swig, libgif, libgsf-1
• you probably don't need libxml2-dev (libvips doesn't use it, we're expat)
• I would use libspng instead of libpng -- it's faster and more secure
• don't use matio, it's not safe against untrusted data
• are you are you need cfitsio? I would remove it unless you are certain
• openslide is also probably unnecessary, unless you have a very strong need
• pdfium would probably be faster than poppler, and would not expose you to licensing issues
• libvips uses Highway now in preference to Orc, I would consider swapping to that

[jcupitt]

Your base image is also extremely old, I think I would use golang:1.21.4.

[suntong]

Yeah, agree, just that I cannot do any recent versions with my current VPC because of the E: Problem executing scripts APT::Update::Post-Invoke. I'll try to find another build environment.

[suntong]

Hi again @jcupitt,

I tried here and I see:

$ vips copy smart-crop.jpg x.avif

what would the quality value used by vips be by default when saving avif files, like above?

I'm already using the latest libvips in my imaginary:

$ curl http://localhost:9000/
{"imaginary":"dev","bimg":"1.1.9","libvips":"8.15.0"}

But when converting from smart-crop.jpg above, the converted size is 47083 (from the original 79289),

curl -O "http://localhost:9000/convert?type=avif&url=https://raw.githubusercontent.com/h2non/imaginary/master/testdata/smart-crop.jpg"

when I tried with quality=60:

curl -O "http://localhost:9000/convert?type=avif&quality=60&url=https://raw.githubusercontent.com/h2non/imaginary/master/testdata/smart-crop.jpg"

The saved size is 29977, still not close to the desired 18530 size.

Hence I want to know what the quality value to use to overwrite the default in
https://github.com/suntong/bimg/blob/master/resizer.go#L193-L209

Thanks

[jcupitt]

AVIF doesn't have an official default quality setting. I think we've changed the one libvips uses a few times, but it's currently 50.

$ vips heifsave
save image in HEIF format
usage:
   heifsave in filename [--option-name option-value ...]
where:
   in           - Image to save, input VipsImage
   filename     - Filename to save to, input gchararray
optional arguments:
   Q            - Q factor, input gint
			default: 50
			min: 1, max: 100
   bitdepth     - Number of bits per pixel, input gint
			default: 12
			min: 1, max: 16
   lossless     - Enable lossless compression, input gboolean
			default: false
...

[suntong]

Oh, thanks for the reply, with quality=50, the imaginary produces the size of 18441, quite close to the desired 18530 size. Perfect!

Case closed!

Thanks