FTA: “So far to the new OAC codebase there has been some tuning adjustments, renaming various symbols to using an "oaci_" prefix and other preparations for establishing the new Open Audio Codec project,”

So, basically all we know is that it’s a fork of Opus.

https://linuxiac.com/aomedia-begins-developing-oac-next-gene... agrees:

“Project documentation states that OAC is experimental and not production-ready. There is no finalized specification, standardization timeline, or guarantee of backward compatibility. It is also important to note that OAC currently mirrors Opus capabilities, with no publicly documented functional advantages.

[…]

In other words, at this stage, OAC appears to be just a development fork of Opus under the Alliance for Open Media’s governance. Whether it ultimately replaces Opus or evolves into a complementary format remains to be seen.”*

I am not that familiar with audio codecs, yet I think it's exciting if it means "music files will get smaller while keeping as much information". I keep ~50GB of FLAC music on desktop, but mostly I use MP3 320Kbps "mirror" of the music library, which is easier to sync to phone with Syncthing. the quality loss is... noticeable at best.