Note that AAC (presumably they mean "Main Profile" rather than AAC-LC) has effectively the same efficiency as Opus. HE-AAC and HE-AACv2 have a higher efficiency than both Opus and AAC, and works great at lower bitrates in comparison to AAC.
Note that AAC (presumably they mean "Main Profile" rather than AAC-LC) has effectively the same efficiency as Opus. HE-AAC and HE-AACv2 have a higher efficiency than both Opus and AAC, and works great at lower bitrates in comparison to AAC."
This chart just roughly outlines (according to the feeling of Opus developers at that time) what to expect from Opus - a wide range of useful bitrates. It's not anything that was actually measured or something that can be used for drawing any conclusions from it. I mean - those nice curves and lack of any detail about the codecs used should give it away.
According to public (double blind) listening test that were performed by the Hydrogen audio group Opus does win over best HE-AAC codecs available at time when the test was performed - both at 64kbps and 96kbps bitrates [1] (Multiformat Tests).
Regarding your claim that Opus is better than HE-AAC, here's a "Quality vs Bitrate" chart from opus-codec.org, the home of Opus: https://opus-codec.org/static/comparison/quality.svg
Note that AAC (presumably they mean "Main Profile" rather than AAC-LC) has effectively the same efficiency as Opus. HE-AAC and HE-AACv2 have a higher efficiency than both Opus and AAC, and works great at lower bitrates in comparison to AAC.