AAC

[Charles Martin]

> From: Matthew Guemple <mo.og at verizon.net>
>
> Ok... so a 128 sample rate AAC will be "better quality" than a 128 MP3?
> I don't get it. Does that not just negate the point of sampling rates?

No, it just means the "rule of thumb" is different.

If you've been encoding your MP3s at 160 or 192, you can probably 
encode the AACs at 128 and they will sound the same or better ... 
meaning you save space.

If you've been encoding your MP3s at 256 or 320 (and yes, people do 
this), you can encode the AACs at 160 or 192 and save a LOT of space 
without sacrificing sound quality.*

*compared to the sound quality of MP3s that is, and it's a given that 
AAC *or* MP3 are inferior to the original CD.

Different people have different sensitivities to music -- I find that I 
cannot distinguish a 192kbps MP3 encoded with LAME from the original. 
Maybe that makes me a complete plebe, but it means that I can probably 
encode the same song as a 128 AAC and not notice any difference, 
meaning I save about 1/3 the size. This can really add up when you rip 
large numbers of songs (and I have 1500 CDs to get through).

Experimentation to find the "optimum" AAC sample rate for your tastes 
are encouraged. I suspect headphone-wearing classical aficionados are 
going to need something better than 128AAC, while metalheads probably 
wouldn't notice if you cut it at 96kbpsAAC because they're partially 
deaf already anyway. :)

For me personally:
The 128kbps AACs from the iTMS are fine because they are sourced from 
the masters, NOT a CD.
If I'm making AACs from CD, I tend to use 160kbps unless it's a 
particularly complex piece, then 192kbps.
For MP3s, I use LAME-encoded 192kbps for everything except jazz & 
classical, then it's 256kbps.

(since I still make lots of MP3 CD compilations for the car, I don't 
tend to encode AACs myself much -- yet.)

YMMV.

_Chas_

"Here is the thing you will learn from really using an OS X Macintosh, 
and must somehow accept on faith if that's what it takes to get you to 
Switch: Apple makes design decisions based on a sincere desire to make 
your life better." -- Glenn McDonald