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Dumb question about itunes from digital downloading newbie

post #1 of 12
12/17/05 at 11:46am
Thread Starter 
My father is getting into itunes and is concerned about sound quality of his downloads (he is an audiophile, too) and is asking me questions I can't answer, so I need your help (I'm still stuck in the 20th century and listening to store-bought CDs). I know the answer is in here a thousand times over, but I don't know what to search for.

I assume the versions of the CDs on itunes are compressed (lossy) in some way. What are the technical differences between a download off itunes and just buying the CD in the store? He would be just burning the itunes songs onto a CD-R to play in a standard CD-player, not an mp3 player, or a computer, and ideally, he would like a bit-perfect copy of what he would otherwise get with a standard CD.

How much of a sonic difference would there be between a downloaded itunes CD-R and a store-bought pressed aluminum CD on a better-quality home system? I assume this is a typical bone of contention (like with cables), and studies from the makers off lossy compression schemes "proving" that differences aren't detectable, but let's say you have subjectivist audiophile tendencies, and a decent system, can you hear a difference? What are the technical differences between downloaded files off itunes and their equivalent normal CD versions? Do things like jitter become a factor?

I also assume that not all itunes tunes are created equal. Are there different encoding schemes on itunes, and how do you tell what file format a particular album on itunes is? What is preferred format to use? Can you select a "bit-perfect" non-lossy version, or are you always buying a compressed file of some kind?

As you can see, I'm old-school and I just don't trust downloaded music. Bottom line, can I tell a difference between the CD I download off itunes and the one I bought in a store on a high-quality home-based system?

Thanks!
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post #2 of 12
12/17/05 at 12:42pm
iTunes uses 128K AAC, which isn't near cd-quality, but is apparently fine for most people. I'd personally just buy the actual cd's, as you'll get better qualityand can rip it to whatever format you want
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post #3 of 12
12/17/05 at 9:21pm
Quote:
Originally Posted by markl
Bottom line, can I tell a difference between the CD I download off itunes and the one I bought in a store on a high-quality home-based system?
I just don't understand.. You have already downloaded stuff from iTunes, yet you need to ask someone else if YOU can hear a difference?

If you have to ask..
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post #4 of 12
12/17/05 at 9:56pm
Markl while there are debates about human perception at high bitrates of the better lossy codecs (LAME MP3, AAC, Ogg Vorbis), the debates lessen as you move down those rates and while 128 AAC is surprising good for the bitrate, it's not CD quality.

It is probably best for you to take a reference CD and encode at 128 AAC and compare to the CD (play both through iTunes or burn the 128 version). That will indicate the quality you can purchase off of iTMS.

There are services with higher bitrates, but most actually have less (128 WMA is worse).

You may also find this worth reading.
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post #5 of 12
12/17/05 at 10:50pm
Thread Starter 
Quote:
I just don't understand.. You have already downloaded stuff from iTunes, yet you need to ask someone else if YOU can hear a difference?

If you have to ask..
I have edited the post to make it clearer. I am not downloading anything, my father wants to get started with the itunes service, but he is concerned with sound quality. He asked me because he knows how far into this audio stuff I am, but I had no answers for him as I do not download, so I am asking in here to pass on to him.
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post #6 of 12
12/18/05 at 7:08pm
While the songs on the iTunes Music Store are encoded at 128 AAC, they are usually encoded from better sources than a standard CD. So, they SHOULD sound slightly better than a song encoded at 128 AAC off of a store-bought CD.

I prefer buying the CDs, since I can sometimes get them for less than the iTunes prices. When I used to encode my CDs at 160 AAC, I noticed that some songs had slight distortions. I now encode my iPod stuff at 320 AAC, just so I don't have to worry about whether or not I chose too low of a bitrate.

Keep in mind that the type of song also plays a role. I have a few Rap and Hip-Hop songs from the iTunes Music Store, and they sound just fine at 128 AAC. In fact, I suspect most Rap and Hip-Hop would sound just fine encoded at less than 128 AAC, but I'd never even consider encoding Classical stuff at that low of a bitrate.
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post #7 of 12
12/18/05 at 7:55pm
Thread Starter 
Quote:
they are usually encoded from better sources than a standard CD.
No disrespect, but I highly highly highly doubt this. Who told you that?
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post #8 of 12
12/19/05 at 2:11am
It was widely reported during the iTMS launch that original masters were used for some encodings. How many they were then and how many are ongoing now has never been stated anywhere as for as I know.
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post #9 of 12
12/19/05 at 11:48am
Thread Starter 
Color me highly skeptical that there's a mastering house that is being sent any master tapes to specifically create itunes content. Why would record companies pay for that expensive extra step just to create a lossy version for download to be played back on crummy equipment generally, when you could just send itunes a regular CD for free for them to chop into smaller bits for downloading fodder? Makes no sense to me.
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post #10 of 12
12/19/05 at 3:04pm
'cause at least initially iTMS was the only industry supported service and Jobs had his way and it was in everyones interest for it to succeed (how quickly the companies turned as Apple has fought against increasing prices above $.99). Also at least initially (don't know now) the record companies assisted in the encoding. Not sure if that meant Apple shipped them a computer or what.

Again by now the percent of albums from originals could be 75% or .5% (it's not talked about anymore), but that was definitely discussed at iTMS launch.

Now since 128 AAC is pretty substantial compression (though again surprisingly good for that rate), I'm not sure anyone has proven masters to 128 AAC resulted in higher sound quality than CD to 128 AAC. Remember Jobs pretty much said two seemingly at odds statements - 128 was indistinguishable from CDs (audiophiles were even mentioned) and many of the recordings were taken from "higher quality" masters. So if you can hear the higher quality of masters over CDs, is it possible you couldn't hear it between CDs and 128? Markl let your skepticism fly on that one.
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post #11 of 12
12/19/05 at 3:25pm
Something else to consider... Supposedly, the AAC encoder built into iTunes uses the default, NORMAL quality encoding. If you use Quicktime (or maybe it's Quicktime Pro), you can specify the BEST quality for encoding, but that means you have to encode the songs from outside of iTunes, which most people don't want to or know how to do.

So, perhaps Apple uses the BEST encoding quality for their iTune Music Store content?

If you really care, just purchase a song from ITMS and compare it to what you ripped from a CD. After all, isn't the mantra of this place "Listen for yourself"?
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post #12 of 12
12/19/05 at 4:02pm
Here's what to tell Pops-

"Dad, iTunes compresses all of their tunes into 128AAC, no exceptions. To Jahn's ears at least, that means they are ALL of worse quality than the original Redbook CDs, and worse even than if you take that Redbook CD and compress it into a 256VBR AAC format. However, the good news is that iTunes offers some very rare and exclusive tunes that are hard/impossible to find anywhere else, so it's worth browsing your fave artists to see if there are any nuggets there worth mining. The best part is that the previews will sound IDENTICAL to the full purchased rip, so you know what SQ you will be getting, and can decide for yourself if that particular track is worth the $.99. Case in point, sometimes iTunes has an original album on there, and the remastered version too, and you can tell the difference in the SQ."
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