It’s worth mentioning surround encoding improvements in 1.1, partly because quite a few people are unaware that Opus even supports surround audio. It does— up to 255 channels, same as Vorbis. Also similar to the early Vorbis releases, surround encoding in Opus 1.0 was mostly untuned. The quality was good, but it was not particularly efficient.
The 1.1 release includes several simple but significant surround encoding upgrades, mostly involving smarter use of bit allocation.
Congrats to Adisa and the HHCF!