Best way to convert thousands of webp images (quiz app) to avif (settings++)

[gregjotau]

We have a few thousand webp images (and growing) that we want to convert to avif, it is mostly about "traffic situations":

What is the best way of doing this? (settings, flags, quality level etc.)

We want as small file size as possible, while the image has to be good enough for the question to be answerable from the image.

cc @Vladislav-Prokh

[y-guyon]

Thank you for your interest in libavif.

What is the best way of doing this? (settings, flags, quality level etc.)

Assuming you already converted your WebP images to PNG (with dwebp for example), I would suggest starting with default avifenc settings, tuning them further as needed.
If the default values do not answer your needs, --qcolor and --speed impact the file size, visual distortion, encoding and decoding speeds. --yuv 420 or --sharpyuv could be beneficial for low and medium quality pictures. More advanced options exist, please see avifenc --help.

We want as small file size as possible

That would probably be avifenc --qcolor 0 --yuv 420 input.png output.avif.
Have you also considered rescaling your images to smaller dimensions?

the image has to be good enough for the question to be answerable from the image

That is subjective. You would have to experiment with --qcolor values over multiple pictures to tune it to your likening.

[gregjotau]

Thanks, we'll look into rescaling (for some images) and the options you mention.