Someone unknown says that last patent on AC-3 expired today
The first rule or journalism should be, of course, "who says this?". Informations failing to establish the identity of the informer have no credibility. And sadly, this is the case today. There's information in a website at the domain ac3freedomday.org saying that the last patent over AC-3 expired today. No information is provided at the website about the author's identity, and the websites domain itself is registered in an opaque way which prevents getting the slight information about the domains owner.
But nevertheless, I am publicising this information because it is objetivable and falsifiable: the information about it is objective and public, so anybody with enough knowledge of patents and their legal terms can find out about its truthfulness in a quick and certain way.
The Last AC-3 Patent Expired on March 20, 2017
https://ac3freedomday.org/
It's probably true given how old AC-3 is but of course: "Is AC-3 any good? Should I use it for new stuff? No, of course not. AC-3 is over 25 years old and horribly inefficient."
For sure - Opus is technically superior to AC-3 in every way: http://opus-codec.org/