SeeMoreDigital: 32 and 64 are cook. 96 and above AAC. Note that you can use
D-C's useful RM analyzer/shell extension and get all the details when right clicking on any RealMedia file (rename to .rm first, D-C did not know about .ra when he wrote his tool).
Re distortion: no, not to my knowledge. I have been playing these files in many different players, and/or after various conversions to other container formats, and not noticed any problem. What kind of distortion, and which of the codec flavors? There are a number of steps you can do to isolate the problem : change player, change decoder, change format (to mkv, then aac).