I have been wondering about something since around June/July this year when Coding Technologies started throwing the term "AACPlus 2" around. I first saw AACPlus 2 mentioned concerning AOL/WinAmp licensing AACPlus 2 in a press release on the CodingTechnolgies.com web site.

What I haven't yet seen is anyone discussing what the difference between AACPlus 2 and the original AACPlus are (quality, improvements, etc.). Is AACPlus 2 better?

I stumbled across an interesting PDF presentation put out by Coding Technolgies to be presented at tomorrow's (Tuesday's) Cellular Telephone and Internet Association (CTIA's) Wireless IT and Entertainment 2004 conference by Apple's director of QuickTime product marketing, Frank Casanova. You can view it on their web site at:

http://www.m4if.org/exhibitions/IBC2004/pr...4-S.Meltzer.pdf

This document mentions AACPlus 2, original AACPlus and the fact the XM satellite radio uses an "early version of AACPlus". Hence, it would appear there are at least 2 different version of AACPlus according to Coding Technolgies' chart on page 13 of the PDF document : MUSRA Scores relative to 7kHz anchor, where it shows different numbers for AACPlus 2 and original AACPlus. What even is a MUSHRA score?

Since AOL just licensed AACPlus for WinAmp a few months ago, and when RealPlayer 10 was released in January 2004 the CT press release said nothing about AACPlus 2 (just mentioned AACPlus), is it correct that Real does not use the AACPlus 2 codecs? Is this new Producer updated codec that they just put out Real's revision to add AACPlus 2 support?

Does AACPlus 2 only factor in improved encoding or should all players come up to AACPlus 2 specs for optimal playback quality? If anyone has any answers about this it would be most appreciated. I just haven't found any detailed info about AACPlus version 2 anywhere, especially how it is better than original AACPlus.

I'm not sure, but from the looks of it, I would suspect that AACplus 2 is HE AAC + Parametric Stereo, that was tested in my 32kbps listening test.

MUSHRA is a listening test specification created by the EBU (European Broadcasting Union), as ABC/HR is a specification developed by the ITU (International Telecomunications Union). IMO, ABC/HR is considerably better than MUSHRA. A good example of MUSHRA comparator is Psytel's WavRate. It used to be available at audiocoding.com, but didn't check it since Menno moved the site.


It's interesting that CT doesn't mention Ahead's HE AAC implementation in that PDF. For understandable reasons, they only want to market their own stuff...

Thanks for the information rjamorim. It will be interesting to see if Apple has licensed this AACPlus v2 codec for use in their iTunes software, iPods and Quicktime as many people are rumouring it has. iTunes Music Store is anyone's guess. I guess we'll have to wait until both announcements from Apple tomorrow (at the U2 "special announcement" and this one at the other conference's keynote address given by Apple's Frank Casanova).

There sure seems to be much being stirred up on the MacRumors site, as many people there seem to think that AACPlus is something brand new, same as CD quality at 48k, worthy of re-ripping their entire CD collections again and perhaps better than sliced bread since Apple may be associated with it. For some interesting chuckles about this:
http://forums.macrumors.com/showthread.php?s=&threadid=94765

If you want more rumours straight (?) from Apple's awesome rumormill:

http://www.apple-x.net/modules.php?op=modl...order=0&thold=0