Standards Compatibility

[joshstoik1]

First of all, thank you for all of your amazing image work!

It looks like Chrome 91 (current beta) is requiring extra format compatibility for AVIF files. Images generated by cavif that work fine in the current Chrome stable will stop working down the road.

See e.g. https://bugs.chromium.org/p/chromium/issues/detail?id=1198455&q=avif&can=2

Running an example cavif-generated image through the AOM AVIF Validator turns up the following issues:

• [miaf][Rule Standards Compatibility #1] Error: The HandlerBox shall be the first contained box within the MetaBox
• [miaf][Rule Fix Compoliance Warden miaf validation - add "miaf" to compatible brands list #2] Error: compatible_brands list shall contain 'miaf' (not found) and 'mif1' (found)
• [miaf][Rule Add a mandatory ispe property to the alpha image #4] Error: 'hdlr' not found in MetaBox
• [miaf][Rule #24] Error: Found no 'pixi' associated for 1 displayable (not hidden) images (ItemIds={1})

(I believe it is primarily the lack of "pixies" Chrome is upset about. 😄)

I'm guessing this library (rather than ravif) is where fixes would be needed, but am unsure.

[baumanj]

I'm guessing you already know this, but since Chrome relies on libavif, the compliance changes come from there. If you want to stay ahead of these kinds of changes, following the libavif issues with the compliance label are probably a good way.

mp4parse-rust has similar changes which will land in Firefox soon and you can similarly follow issues with the avif and compliance labels there.