[Enhancement] Support to the AVIF format

[MysterHawk]

Good evening,

I've just installed this project on my server, unfortunately I noticed that the AVIF format is currently not supported.

I'm using this format because it is currently the most efficient one in circulation, better 20-30% compared to WebP, and it is an open royalty-free standard (https://avif.io/).

Do you have plans to support this type of format?

To my knowledge, at least ImageMagick supports this format, but I'm not sure about ExifTool (on a Google search I noticed that some people already worked with it, though)

[MysterHawk]

I've just noticed that I can still upload them correctly if I add the .avif format to the list of raw_formats

But even if I do this, the images will be converted automatically afterward to .jpeg in the gallery, is there a way to change this?

[ildyria]

Do you have plans to support this type of format?

I was not aware of that format. At the moment, most of the development is done by @qwerty287 and me. As you can guess we have other priorities.
If someone wants to add upload support for avif format we will most likely merge the pull request (assuming it passes our CICD and propert tests are provided).

But even if I do this, the images will be converted automatically afterward to .jpeg in the gallery, is there a way to change this?

No. Unless you want to dive very deep in the code.

Furthermore, I am strongly against adding such conversion for the following reason, while the support seems to be present around modern browser, it is still not the case on local desktop: To quote Google.

How do I open an AVIF file in Windows 10?
The easiest way is using Chrome (v85 or later) or Firefox (v93 0r later) web browser because there' s no need to download and install any add-ons.

Lychee provides the ability to download pictures, going for a new format like avif would impact the non-tech-savy users (e.g. visitors) of Lychee.

For Exif tool, the support may need to be added here :
https://github.com/LycheeOrg/php-exif