Well, it is legal, since that guy, who wrote the patch for ffmpeg, to enable libaacplus support, made it that way the patch downloads the publicly available source code from 3gpp website, and he did mention that its publicly available, and he used that information to write his code.. During the ./configure or make (im not sure), the scripts download the code from 3gpp website automatically and compile it into that library.. So, I guess the guy didnt just take the code and embedded it into his library.
Quote from
http://tipok.org.ua/ru/node/17 :
"3GPP released reference implementations 3GPP High Efficiency Advanced Audio Codec (HE-AAC) Codec (3GPP TS 26.410 V 8.0.0).
Reference implementations are available as a source code, but the code uses #define to choose code options. There is a common practice to compile reusable code as a shared library. Packages released here make required changes and provide AAC+ libraries as a shareable code."
Anyway, thanks for your help, I really appreciate it