AAC (itunes music store) Vs. AAC (Itunes 4.1 ripped from cd)
[184 byte] By [zerock] at [2007-11-9 14:56:18] 
hmm i noticed maybe is just my ears that 128k music store aac's sound better than those encoded by itunes 4.1, they sound more like 160k, am i crazy or does someone agree with me.
# 1 Re: AAC (itunes music store) Vs. AAC (Itunes 4.1 ripped from cd)
I think I've read somewhere that Apple is not using the regular Quicktime AAC codec for the iTMS, but an 'industrial-strenght' one that takes much more cpu and time to perform, but it renders slightly better results.I don't have the exacts facts now though :rolleyes:
aromanos at 2007-11-15 17:40:35 >
# 2 Re: AAC (itunes music store) Vs. AAC (Itunes 4.1 ripped from cd)
I JUST posted this in another thread, so copying in...The iTMS uses 128 kbps AAC. However, they are also often going back to the original source material, which is better than a CD. The Quicktime codec has "good, better, best" settings, and iTunes uses "better". For a CD, "better" and "best" give identical results. Since Apple (or, rather, the record companies) are working from source material that is better than CD, they are probably using "best" for the iTMS.
thenightfly42 at 2007-11-15 17:41:35 >
# 3 Re: AAC (itunes music store) Vs. AAC (Itunes 4.1 ripped from cd)
wow, didn't know that, great info.Musicroom :D
musicroom at 2007-11-15 17:42:45 >
# 4 Re: AAC (itunes music store) Vs. AAC (Itunes 4.1 ripped from cd)
yeah, no kiddingthat's some good planning at work on Apple's part
Wolfman200 at 2007-11-15 17:43:40 >
# 5 Re: AAC (itunes music store) Vs. AAC (Itunes 4.1 ripped from cd)
hey guys, to avoid cross posting, could you please check my post here: http://www.ipodlounge.com/forums/showthread.php?s=&threadid=13364it's basically the same question/comment here. i'd love some input, especially from thenightfly42. i'd love to know where you heard the info about source material.
thanks
Skip
SkippyMcHaggis at 2007-11-15 17:44:39 >
# 6 Re: AAC (itunes music store) Vs. AAC (Itunes 4.1 ripped from cd)
Apple is encoding their AAC songs for the iTunes Music Service using the original 24-bit digital master recordings. Although most people think CDs are equivalent to the master recordings, they are not. CDs are typically produced with 16-bit encoding.Since Apple is using a higher quality source material, their 128Kbps AAC encoded songs will sound better than the ones you encode yourself from your own CDs.
I didn't realize this until after I had encoded a large part of my collection in 128Kbps AAC. Although it probably doesn't matter to most people, I will probably spend a few weeks re-encoding my CD collection at 160 or 192Kbps AAC, or maybe wait until January, when it's rumored that iTunes 5 will be released, and see what new features that update may bring.
Jim Reese at 2007-11-15 17:45:38 >
# 7 Re: AAC (itunes music store) Vs. AAC (Itunes 4.1 ripped from cd)
WRT to 16 bit vs 24 bit, remember this refers to the dynamic range possible in each song. Think of it as the maxium difference between the loudest and quietest sound allowed.24 bit is useful for mastering because it allows for headroom as you edit. That way you can do whatever you want and the loss of precision from rounding errors will all be in the upper 8 bits (hopefully).
However its more or less useless for actual listen vs. 16 bit because very little music uses anywhere near the whole 16 bits allowed on CDs. In fact most music uses only a tiny fraction as 16 bits allows for an enourmous dynamic range (96 db!). That means with 16 bits you can go from the threshold of hearing to a jet engine, and still have some range left over!
24 bit extends that even further to 144 db, which is enough to go from threshold of hearing to well over the threshold of pain! So while recording from 24 bit masters is a cool idea, its not going to effect encoding quality.
saratoga at 2007-11-15 17:46:40 >
# 8 Re: AAC (itunes music store) Vs. AAC (Itunes 4.1 ripped from cd)
Actually encoding from a master will increase quality, but only a little bit. Encoding in 16 bits is ok, and it sounds fine, but you never know how a song is supposed to exactly sound if there is no headroom for error. When encoding in 24 bits you know that the song will sound exactly as it is supposed to, even though 7.5 out of the 24 bits are useless. What I am saying is that 24bit encoding theoretically allows for a more exact copy of a song, even though it may end up sounding exactly like a 16bit encoded version.breakaway1029 at 2007-11-15 17:47:43 >
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