Replacing the Accept codecs parameter

IIUC, the Accept spec no longer allows a codecs parameter:

Previous specifications allowed additional extension parameters to appear after the weight parameter. The accept extension grammar (accept-params, accept-ext) has been removed because it had a complicated definition, was not being used in practice, and is more easily deployed through new header fields. —RFC 9110: HTTP Semantics

Container formats increasingly don’t tell you enough about the codecs used inside of them (especially for video, but even for images [which are increasingly encoded using the keyframe bits of video codecs]). I have hoped for more codecs usage going forward, not less.

Media Capabilities is great if you are orchestrating loading via Javascript. What if you aren’t?

  • How do existing browsers deal with <picture type> and <video type> that contain codecs? How could/should future browsers/HTML solve this using markup?
  • I’d (also?) strongly support solving this problem with Client Hints, given its opt-in, privacy-preserving design.