From Hydrogenaudio Knowledgebase
aacPlus was a variant of AAC developed by Coding Technologies, which later evolved into the MPEG-4 standard profiles HE-AAC and HE-AACv2. It pioneered the techniques of Spectral Band Replication (SBR) and Parametric stereo (PS). AACplus itself is no longer developed and is considered obsolete.
- http://www.codingtechnologies.com/products/aacPlus.htm Encoding Technologies AAC pages.
- http://www.tuner2.com A site listing Internet radio stations which use AAC plus.
- http://forum.dbpoweramp.com/showthread.php?t=7107 an aacPlus encoder
- http://teknoraver.net/software/mp4tools/ another aacPlus encoder