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MP3 vs. AAC
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Dedicated MacNNer
Join Date: Sep 2001
Location: the Netherlands
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Offline
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Hey,
Just ran a quick comparision: I took a nice Rossini song (from cd)and let iTunes convert it to mp3, 160 kbs and after that I let Quicktime convert the same song from cd to aac audio format, 160 kbs (this takes ages...). Besides there's an obvious difference in sound quality, I noticed the following: in iTunes, playing the mp3 version takes on average some 25% of my ibook's cpu time (while running nothing else but 'top' in the terminal): it varies between 16-22% and now and then it peaks to a range of 30-40%. Playing the mp4 version, however, takes cpu time ranging 10-20% (usually around 13-15%) and never peaking any higher than 20%.
Now if iTunes could only rip cd's and create mp4 files (and also doing it at an acceptable speed)...
greetz,
Stefan
(ibook 600/384)
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Mac Elite
Join Date: Jul 2002
Location: Youngsville, NC
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That's good to know, how much smaller are the files? It would be a lot of work to re-rip my CD's, but If i could get some more mileage out of the 5GB iPod, that would rock
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Dedicated MacNNer
Join Date: Sep 2001
Location: the Netherlands
Status:
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Originally posted by dampeoples:
That's good to know, how much smaller are the files? It would be a lot of work to re-rip my CD's, but If i could get some more mileage out of the 5GB iPod, that would rock
Well, since these files both have a bitrate of 160 kbs, these are of the same size. Probably a 128 kbs MP4 has a comparable sound quality as a 160 kbs MP3. So, if all your MP3's are 160 kbs, you could save about 20% of space by switching to 128 kbs MP4. Just give it a try!
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Addicted to MacNN
Join Date: Jun 1999
Location: Las Vegas, NV, USA
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Originally posted by dampeoples:
That's good to know, how much smaller are the files?
There is nothing inherent in AAC that makes the files smaller than MP3. It depends upon what bit rate you encode them at. If your MP3s were encoded at 160bps, for example, and you encoded your AAC files at 160bps, they would be the same size but would sound better. If you encoded them at 128bps, they would be smaller but might sound the same as your 160bps MP3s.
So the file size is totally up to you. You could also get more mileage out of your 5GB iPod by encoding your MP3s at 96 or 128 rather than 160bps.
It's all up to your own subjective opinion of sound quality.
Chris
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Fresh-Faced Recruit
Join Date: Apr 2002
Status:
Offline
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The IPod will not play AAC/MP4 format. Bummer, huh? Another thing I just discovered. My ITunes library directory recently took a dump. I deleted all the prefs and library files. I opened ITunes, it acted like it did when I first got it and asked me if I wanted to find all the music on my computer. It did not recognize the MP4s.
The other thing is that Quicktime doesn't encode song info data so you have to input all that by hand. All in all, even with the much better sound quality, the time required is not worth the hassle for me.
BTW there is a program called Make Mine MPEG-4 v4.0.1
For iTunes 3 and QuickTime 6.x Pro
< http://www.malcolmadams.com/itunes/>
Automates the process of ripping and then encoding iTunes CD tracks as MPEG-4 audio files using QuickTime 6.x Pro. MPEG-4 audio encoding (also known as Advanced Audio Coding, or AAC) allows for higher quality compressed audio at smaller bit rates -- and thus, smaller file sizes.
This works really well!
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