Sidebar Sidebar
Become a MacRumors Supporter for $50/year with no ads, ability to filter front page stories, and private forums.

Help Choosing Bit Rate for Importing CDs in ITunes

Rantipole said:
I'm in a similar predicament. I would like AAC for my purposes, since it sounds better bit-for-bit than MP3. However, there are times I would like to make an MP3 CD for playback. I have not yet gotten my new computer, so I don't know: with the latest version of iTunes, is it easy to just convert a bunch of AAC files to MP3? Or, would the conversion just ruin the sound quality?
Click to expand...

Well, it is really easy to just select and convert. If you have a high enough AAC file and convert to a lower bitrate MP3, it shouldn't sound bad, or even lossy too much. But if you go from 256 AAC ––> 192 MP3, or something similar, you should be fine.
–Chase
 
I just realized there's a couple of terms here I don't know. What is OGG? And how about VBR? I thought that was a PC thing. We have it to? How do I select it? In the past, I've just gone to import option and selected bit rate and AAC. There are more things I can control? Thanks for the help.
 
OGG is another format, you can learn more about it at http://www.vorbis.com/music.psp. Here is a list of applications that support OGG in Mac OS X.

VBR is Variable Bit Rate encoding, that will change the bitrate during the "song." It's easier to say that it is kind of the opposite of CBR, or Constant Bit Rate encoding. In CBR, the bit rate is the same. In VBR, it varies.

I don't believe AAC supports VBR in the same sense as MP3. In iTunes, you can't select VBR for AAC, but for MP3 you can. I hope that helps you out.
–Chase
 
Okay, question.

If I rip all my music to AAC from now on, and I want to make an MP3 CD, does checking off the MP3 CD option in the options thing make the AAC files convert to MP3 before they're burned?
 
neoelectronaut said:
Okay, question.

If I rip all my music to AAC from now on, and I want to make an MP3 CD, does checking off the MP3 CD option in the options thing make the AAC files convert to MP3 before they're burned?
Click to expand...

According to iTunes' help, any format that's not MP3 will not be burned to the CD. So no.
–Chase
 
johnnyjibbs said:
It would be interesting to make a CD of one song, but with each track in a variety of bitrates (as someone mentioned earlier) - e.g. AIFF, Apple Lossless, 192 MP3, 128 MP3, 128 AAC, 192 AAC, 320 AAC, etc - shuffle them around and then ask an "audiophille" which one is the AIFF (best quality). I bet you 9/10 times they wouldn't get it right. :p ;)
Click to expand...

I agree! The key here is to do a blind listening test. Anything else is inherently biased. Why? If you go through and listen to a song at 128kbps, 192, 320, lossless, and know which one you're listening to, your brain will trick itself into thinking the higher quality ones sound better. I found this to be true when I was first trying to determine my optimal bitrate. I complimented myself on the great ears I must have, to hear all those subtle differences. :D

Then I did a blind listening test. For each bitrate, I converted it back to AIFF. Then I wrote a little program to randomly pick one of the compressed/converted AIFFs along with the original source, and randomly name them "A" and "B". Then it randomly made a copy of one of those and called it "C". I had my program keep track of which was which, but you can just have a friend do it in the Finder while you're not looking. Then I listened to all three AIFFs (A, B, and C) and tried to guess which was the original and which was in there twice.

I found the 128 kbps AAC stumped me often but not always. With 160 kbps, my answers were no better than random guesses. This is with a good pair of headphones, but no audiophile stereo. So that's what I use, and my 370-CD collection takes up about 23.5 GB. Perfect for my 27.9 GB iPod. :p This was after I was sure I could hear a difference between 320 kbps and the original! Guess I was wrong. I mostly listen to my iPod in the car, and I couldn't be happier with the 160 kbps. I've never had a problem with the quality of my iTMS purchases either.

If you really want to choose the best bitrate, I suggest you go through this procedure. Pick a few songs you love and really know well, preferably from a few different genres. Try to listen on the equipment you'll be using most, as that definitely makes a difference too. Perhaps if I had a really good stereo, 160 kbps would have audible flaws, but I guess I'm happy being ignorant. ;)
 
Here's an idea: Just import everything twice- once uncompressed and once in a half-decent mp3 format. Then buy an external hard drive and keep all of the large files there while putting the mp3s on your iPod. That way, if you end up with a Mark Levinson system down the road, you'll be okay. ;)

Bankshot, that blind comparison test you mentioned is genius, by the way.

Oh, and I'm also having some regrets about importing in AAC. It's not that the there's a quality problem. It's just that it's a pain in the butt to burn a full 800 MB of mp3s for a friend. I was listening to my iPod in the car when my buddy asked me to burn him a CD. I downloaded some kind of LAME importer from Versiontracker and did a batch convert. It would have been much easier to just pick all the tunes and hit a "burn as mp3 files" button. Or is there an easier way to do things? I guess Apple is sort of torn between their ease of use and promoting AAC.

Squire
 
Squire said:
Bankshot, that blind comparison test you mentioned is genius, by the way.
Click to expand...

For curiousity see these:

http://www.pcworld.com/reviews/article/0,aid,64123,pg,2,00.asp
http://www.recordstorereview.com/misc/aacmp3.shtml

Somewhere, there was one of these where the listeners were *all* audiophiles, but I can't seem to find that one now.

Anyway, it does seem to support that a lot of ppl can tell the diff between 128 and 192. But its interesting how different the score on the second link between non-blind and blind tests of AAC/128 is -- meaning a lot (but not all) of it was in the testers' heads....
 
I'm getting one of those neat Nokia 3300 phones, and it plays the AAC format. Now, it comes with 64MB of memory, so what's the lowest bitrate I can get with AAC and it'll still sound good? 128?

Should I not dip any further down?
 
You must log in or register to reply here.
Register on MacRumors! This sidebar will go away, and you'll see fewer ads.
Top Bottom
Back