MP4, AAC, M4A differences

[Hyper Shinchan]

What are the differences between these standards?

[Baldrick]

http://forum.doom9.org/showthread.php?s=&threadid=62723

[Hyper Shinchan]

Tnx Baldrick. So the MP4 is the official container format for MPEG4 eh?
And M4A is an invention of Apple (so I can understand why my friend with ITune makes M4A and I make MP4 with Nero Recode).
But why Nero is so different with sub and other is a mistery for the umanity!

[celtic_druid]

m4a as far as I know is just an mp4 with custom tags and it is possible to convert mp4's to itunes compatible ones.

Nero uses VOBSubs stored as a private stream.

[midnightsun]

ciao hyper

m4a and mp4 are the same cointainer...apple (maybe others as well, I don't know) calls it m4a when the multimedia content is audio only, I gather, just for the sake of simplicity (so you know that when you see an .m4a file it's an audio file). You can store tags in the mp4 (m4a) container, but not in raw aac, which contains the bare audio data.

Think of it as the equivalent in mp4 to what mkv and mka are for matroska.

[Hyper Shinchan]

Ciao to you midnightsun! Another Italian guy! I'm so happy!
The FAQ that Baldrick had linked is very good! The M4A is only an invention of the Apple, is the same of an MP4 with only audio (the MP4 that you can encode with Nero are MP4, and not M4A), the tag of M4A are stored as the chapters in rhe MP4 movies of Nero Recode 2, with an MP4 features called user space.
But I read all these things from the FAQ of Bond of the Doom9 Forum, is very useful!
For you is better the M4A of I-Tunes or the MP4 of Nero (or elementary AAC, you can also make the audio file in this way)?
P.S.: If it's better to open another Topic, please tell me!
Cheers!

[midnightsun]

Hey!

I very recently (last week) bought an iPod for my sister so now I have iTunes available, but I haven't played with it a lot so at this stage I can't comment on Apple vs Ahead as far as AAC encoders are concerned. The last tests I saw seemed to indicate that iTunes was the best AAC encoder but things change so you never know. By the way Ahead has just updated its AAC encoder with the latest release if I'm not mistaken

[celtic_druid]

Depends what kind of aac. Current version of iTunes as far as I know can't do he aac or vbr encoding. Then again ipods don't support he aac, but lack of vbr could be an issue.

[Hyper Shinchan]

So I-Tunes doesn't support VBR? It's a problem, I think. And it doesn't support AAC HE; so Nero is the best one? The my friends that have the I-Pod and I-Tunes think so too! However, when I will come back I will try I-Tunes!