Yes, CABAC and techniques surrounding it are heavily patented. For this reason, both Opus and Daala use (different) range coding schemes instead, which can also

Yes, CABAC and techniques surrounding it are heavily patented. For this reason, both Opus and Daala use (different) range coding schemes instead, which can also deliver higher performance. One problem with CABAC is that it is highly serial, and ends up being directly clock rate limited in a lot of hardware engines.