I've read the AAC pages (generic (https://wiki.hydrogenaud.io/index.php?title=Advanced_Audio_Coding) and FAQ (https://wiki.hydrogenaud.io/index.php?title=AAC_FAQ)), and as far as I see, it suggests to use Apple AAC, and FDK-AAC (1st and 2nd choice).
Ignoring Apple AAC, is there more detailed information about the FDK-AAC choice? I can't really find much; the listening tests are very old, and also, bitrate-wise, very limited, so I'm trying to find more information to make a sound choice.
The information on the wiki IMO is still very valid, newer versions of this encoders don't bring improvements in quality AFAIK?, just optimizations to encode faster among other things, they may bring improvements in sound quality but I guess is a good idea to read the change-log also going to the source https://www.iis.fraunhofer.de/en/ff/amm/impl.html
I don't think much has changed since the last test, so not much interest in doing more tests.
What bitrates we're you interested in?
I guess this could also vary depending on the target bitrate?
AFAIK Apple supports HE-AAC v1 (SBR), but doesn't support HE-AAC v2 (SBR+PS). So at really low bitrates, maybe FDK-AAC would be better?
There's also other considerations, like the platform to use for encoding. Using the apple encoder on Windows and Mac is easy. I have no idea how to setup on Linux, maybe with wine? And there's people who simply don't like closed source software.
Speaking of "HE-AAC" is there a listening test which covers the transition points of when to use SBR+PS and SBR. I've seen particular bitrates recommended, but haven't seen anything to back it up.
Is it a case of diminishing returns, or is there a point where the more efficient codec is actually detrimental, given the same bitrate?
SBR+PS are approximations of the real high frequencies and stereo channels that sound better than not having them but often only approximately correct. Once you have enough bitrate, it's better to not use them.
I've seen various people test HE over the years. You can find them in the forums, or just try yourself. At very low bitrates differences are not particularly hard to notice.
In my personal testing, with really low bitrates the extensions work as intended, and sound better (to me).
Once I get to higher bitrates, either my ears are not good enough to tell the difference, or my gear is not good enough. So I would like to read on the listening tests of others.
I've seen HE-AAC compared to opus and other codecs. I've seen comparison of HE-AAC from different programs. And I've seen LC-AAC thrown in the test as a low anchor. But I've never seen a head to head comparison of HE-AAC vs LC-AAC at the same bitrate.
But I've never seen a head to head comparison of HE-AAC vs LC-AAC at the same bitrate.
This HA wiki page (https://wiki.hydrogenaud.io/index.php?title=Private_Listening_Tests) has one link: https://hydrogenaud.io/index.php/topic,35438.msg312296.html#msg312296
Or, if you want to see all pictures and original formatting, https://web.archive.org/web/20141227053920/http://www.hydrogenaud.io/forums/index.php?showtopic=35438