Animated AVIF returns “Image not readable” through wsrv.nl

[DavidS-Repo]

Summary

Animated AVIF input fails through wsrv.nl with a 404 error.

The original file is served as AVIF and loads directly in browsers (both Firefox and Chrome based).

Original image

Raw URL:

https://www.davids-repo.dev/ggqol/assets/avif-web/instant-smelting-and-processing.avif

wsrv.nl URL

https://wsrv.nl/?url=https%3A%2F%2Fwww.davids-repo.dev%2Fggqol%2Fassets%2Favif-web%2Finstant-smelting-and-processing.avif&n=-1

Actual result

wsrv.nl returns:

{"status":"error","code":404,"message":"Image not readable. Is it a valid image?"}

Expected result

wsrv.nl should either:

1. Serve the animated AVIF correctly.
2. Return a clear unsupported format error if animated AVIF is not supported.

Context

This was found while debugging this Modrinth issue. Modrinth proxies Markdown images through wsrv.nl when the image host is not allowlisted. Static AVIF images work in the same Modrinth Markdown path. This animated AVIF fails after going through wsrv.nl.

Notes

This does not look like a browser AVIF support issue. I am not sure whether this is an animated AVIF parser issue, a libvips limitation, or a validation step rejecting AVIF image sequences.

[kleisauke]

Animated AVIF sequences are unsupported by libvips and therefore wsrv.nl. Please see the upstream discussion at libvips/libvips#3629.

[DavidS-Repo]

Thanks for checking. That makes sense. I’ll leave this open as a tracking issue for animated AVIF support in wsrv.nl once libvips supports AVIF sequences, but feel free to close it if you do not want to track upstream blockers here.