[G4] M4A - M4P

[Alex]

On Friday, Jun 11, 2004, at 09:14 Canada/Eastern, zhmmy harper wrote:

> What is the benefit of using M4A or M4P, or is it mainly for the 
> benefit of the iTunes Music Store? [...]

M4A is AAC (Advanced Audio Codec); M4P is AAC protected (that is, 
protected against unauthorized decoding). In terms of audio, there is 
no difference between M4A and M4P.

Apple claims that "AAC-encoded files sound as good as or better than 
MP3 files encoded at the same or even a higher bit rate". But this 
claim is really meaningless, because the quality of MP3 encoding varies 
greatly depending on bit rate and on the codecs used in compression. 
So, for the same bit rate, M4A may be better than MP3 encoded with 
Apple's codec, but worse than MP3 encoded with another codec (e.g., 
LAME). To complicate things even more, some codecs are better than 
others at some bit rates, but worse at other bit rates, and some are 
better with one kind of music, but not as good with another.

Have a look at <http://www.xciv.org/~meta/audio-shootout/> for an 
example of AAC vs MP3 comparison.

But, in the end, the only solution is to try different options and go 
with the one which sounds best to your ears. For myself, I do not 
encode music at less than 256kbps, or VBR with the alt-extreme preset 
in LAME v3.90.3.

<0x0192>