I just bought a Philip Expanium CD player that supports AAC files. But it only looks for files ending in .AAC, which iTunes 4 does not make.

Is there a UNIX/Mac OS X solution to convert my ripped .M4A and my purchased .M4P files into .AAC files that my Expanium CD player can recognize?

You can download mp4creator (part of mpeg4ip) from RareWares. Since Apple's decoders only handle MPEG-4 AAC and some other only handle MPEG-2 AAC, I patched it to be able to override the MPEG version header.

- Download the mpeg4ip package.
- Get the AAC track id from the mp4 with "mp4info"
- Extract the AAC track with "mp4creator -mpeg-version 2 -extract <aac track #> <mp4 file>"

I don't know whether the resulting AACs will work on your CD player, but it's worth a try.

About the encrypted MP4s; AFAIK, currently there is no way to remove it. If you live in the EU, you're entitled to break it if it prevents you from using purchased material. So you could reverse engineer it if you want to...

It's worth mentioning that you probably won't be able to strip your AAC files from the .m4p stream, due to the DRM restrictions.

@danchr: reply to my mail, man. :B

Taken from another thread:

====================
BTW A request, anyone who has a MAC, PC and has purchased a track from Apple please send:

The .m4p file before uploading to the iPod, and the resulting .m4p file as uploaded to the iPod (Sveta Explorer will allow it to be copied back to the PC), this is so these files can be examined by the open source world for compatiblity reasons. Email: dbpoweramp@dbpoweramp.com
====================

I have applied your modifications of mp4creator to the windows thanks your diff file. The -mpeg-version switch works when creating mp4 from aac. but it seems not to work when extracting aac from mp4.
Have you noticed the sama issue?
if yes, can you help me to fix this bug?
Regards
Enrico Palmeri

Quick question: Are the iTune music files that Mac users are downloading, are they AAC contained in MP4, or are they just AAC?
And with regards to an answer of this question, here's another: What does the iPod play, MPEG-4 AAC contained in MP4, or MPEG-4 AAC without a container?
And if it only plays AAC without container, do you see Apple supporting MP4 in the future (also, do you see them supporting SBR in the future)?

iPod plays MP4 files, which means AAC (and maybe, CELP) inside a MPEG-4 file format container (.mp4 file)

thank you. At least this means we might see SBR support on the iPod in the future. Ah, so all the iPod does is change the extension from mp4 to m4a. Gotcha. I might just get an iPod now (or when the new Windows version comes out). Have people had any trouble playing Nero encodes on the iPod? (I am simply looking to the future here, if Nero Digital turns out to be as awesome as people are speculating, I may want to use it to encode )

Well, so far I didn't have any problems with playback of .mp4 files encoded with NERO.

I encoded a song using Nero's AAC (5.5.10.35) encoder and sent the resulting MP4 file to a friend running iTunes 6.3 on his Mac. If he just opens it as-is, it launches Apple's QuickTime Player application, which is primarily for video playback. This is because the .MP4 extension is mapped to that app. When he changes it to .M4A, it launches iTunes and plays perfectly.

Apparently there's no difference in the two file formats, only a naming convention which is Apple's way of distinguishing between audio and video files in the OS. -Greg

BTW: Is there any reason for me to check "Export ISO 13818-7 AAC Track"? What is the difference in the file if it is or is not checked? (I'm going for maximum future compatibility here, both in the Apple and PC worlds. Someday I'll own both!)

The "Export ISO...." option in Nero encoder will produce 2 output files, the normal .mp4 and additionaly an .aac (which can be used for hardware players that only play .aac but unfortunately not .mp4, like the Phillips Expanium)