Most of you don't seem to be aware that re-encoding MP3 files (to AAC, for example) further lowers audio quality... a lot, depending on the bitrate settings of the MP3 & AAC encoders.

Btw, the choice of codecs is relevant, too. I find the LAME MP3 codec to be MUCH better than most others I've heard. You find it in some freeware applications, too. "Max" for OSX, for example: http://sbooth.org/Max/

Generally, AAC is more efficient, meaning that smaller AAC files usually sound as good as equivalent MP3 files 130-150% their size. So generally there's nothing wrong with AAC... the re-encoding of your MP3-libraries is the problem.

 You are right on one sense, there is no reason for NINTENDO not to support both.  If we (those of use with 100's of CD converted to MP3 fo rmany, many years)  'just convert' to AAC then...all of our MP3 players won't work.  This is monumentally stupid on Nintendo's part.  90% of the mp4 file are out there are from iTunes and they ONLY work with the iPod they were purchased with. 

Outside of DRM crippled itunes, no one uses MP4 for anything. That is whay every portable device, including EVERY ipod/itouch ad iPhone plays MP3 files! Sheesh!

Ninentdo has managed to create a 'music player' (using the term loosely here) that won't play any DRM AAC llike iPods, and also won't play and non-DRM encumbered MP3 files. 

Let's summarize:

I challenge anyone to find any other music player, that does NOT play MP3.  This is truly a first!

Uhm, it's not 'incredibly superior'. Never was really. It was chosen by Apple beause it had the DRM option, nothing to do with sound quality. Nothing.  It's more like the difference between HD-DVD and Blu-ray.

from the same wikipedia article linked earlier in this thread, posted as proof of AAC betterness:

"However, in terms of whether AAC is better than MP3, the advantages of AAC are not entirely decisive, and the MP3 specification, although antiquated, has proven surprisingly robust in spite of considerable flaws. AAC and HE-AAC are better than MP3 at low bit rates (typically less than 128 kilobits per second)^{[citation needed]}. This is especially true at very low bit rates where the superior stereo coding, pure MDCT, and more optimal transform window sizes leave MP3 unable to compete. However, as bit rate increases, the efficiency of an audio format becomes less important relative to the efficiency of the encoder's implementation, and the intrinsic advantage AAC holds over MP3 no longer dominates audio quality."

My 320k max VBR MP3's average about a meg per minute - an average of 128kps (slightly less actually) and sound like Cd's.  Unless you listen at 64kbps, or streaming things on the web AAC has no real advantage.  AAc was designed to squeeze more into the same 56kpbs modem bandwidth most of us had back in 1997, and to squeeze more audio onto our insanely expensive 500Megabyte  drives.  Whoop de do.

Nintendo is not going to change the market with their new DS.  They are just going to look stupid.

@Jkimball: My three CD players.

@Jkimball: By the way, you forgot all the hundreds of millions mobile phones from your list, that all play AAC.

There's a huge market that supports AAC as a (set) standard.

Besides, is there any music store that sell MP3:s?

And, why can't DSi play AAC with DRM?

amazon.

and un DRMed if i recall correctly.

btw: all those cellphones also support mp3 even the 30$ cheap ones.

DRMed AAC is not playing by others players because of apple itunes monopoly, they should have let others player use it.

the good thing it's they are not DRMing their content anymore and offered un DRMed contend.

i did a experiment, converting songs to AAC take a alot of time!, i don't recommend it, with winamp to AAC it took 400 min for about 600 songs.

I don't know about the R4 but Cyclo is working on a firmware update to the Cyclo Evolution so that it will work with the DSi.  Give it a few months and they will have it working 100%

Not to be rude, but picking WMA was your mistake. Going with a more open format 9lower licensing, stable specs, ect) is crucial to being able to listen to the same music you ripped 10 years from now. MS has pretty much given up on the format as have most HW companies, and that was pretty obvious ever since MP3 got huge. I've been using MP3's since 1996 and have none of these problems. I would have had if I had chosen RealPlayer, WMA, or whatever format Apple was using at that point.

Don't blame Nintendo for your lack of forsight. If you tie yourself to one company's format you are taking a big chance.

What you're completely failing to consider is the fact that CDs are burnt at 128Kbps, so 99.9% of the MP3s out there are at 128Kbps bitrate quality (even if they're ripped at a higher bitrate).

Additionally, any higher than 128Kbps gets difficult to hear the difference. And above 192Kbps is impossible for anybody untrained to hear a difference. So, the lack of an advantage at higher bitrates is pretty negligible.

Lastly, it's not just sound quality that's better. AAC files are also a smaller filesize at the same bitrate - so not only does it at least offer equal quality (and higher, at low bitrates), but it does it while taking less space.

Huh? CDs are burnt at 128kbps? What do you mean?

16 Bit Wav Files are about 1400kbps in size - but you can't compare them to MP3 files at all, because Wav is a lossless format, something MP3 or AAC never is.