Here's a "Quality vs Bitrate" chart from opus-codec.org, the home of Opus: https://opus-codec.org/static/comparison/quality.svg https://opus-codec.org/static/co

Here's a "Quality vs Bitrate" chart from opus-codec.org, the home of Opus: https://opus-codec.org/static/comparison/quality.svg https://opus-codec.org/static/comparison/quality.svg Note how AAC has effectively the same efficiency as Opus? HE-AAC and HE-AACv2 are notably better in comparison, and are usable at lower bitrates than AAC. In cases where "the opposite is very well established", they're talking about AAC-LC. Citations that show otherwise are welcome! In any case, HE-AAC's universality is really beaten only by MP3 (which it trounces).