Switching from MP3 to AAC Without Losing Your Mind | iLounge Article


Switching from MP3 to AAC Without Losing Your Mind

If you’re anything like me, the minute you downloaded iTunes 4 and saw that it supported AAC-encoded files, your mind was bristling with plans to re-encode every mp3 in your music library to the smaller, higher-quality AAC format.

I began the massive project the day iTunes 4 came out. (“Massive” is about the only way to describe re-encoding over 9500 songs from CD all over again.) Remembering the month it took me to get the music onto my hard drive the first time, I was not looking forward to hours in front of the computer, mucking about with ID3 tag info and correcting CDDB’s many, many errors.

Replace Existing

iTunes is one of the best pieces of software Apple makes, and the fact that it is still freeware (knock on wood) is doubly amazing. Each release of iTunes has not only added features, but has done so with intelligence and attention to usability. iTunes 4 did not disappoint; as with any piece of software, the details matter; the detail that increased my admiration for iTunes’ developers the most this time was the “Replace Existing” option.

The authors of iTunes intuited that a great many users would, like me, want to convert huge libraries of music from mp3 to AAC, and that these users were going to re-encode straight from CD to avoid the sound-quality loss that comes with converting one MPEG codec to another. At the same time, they reasoned (rightly) that the same users would likely have invested a great deal of time compiling playlists, rating songs, and adding comments to certain mp3s, information that, were we to re-encode, we’d lose and have to enter all over again.

Hence, the “Replace Existing” option. I discovered the option the first time I clicked “Import” to re-encode a CD: a dialog popped up and in the bottom left-hand corner of the dialog was a button reading “Replace Existing”. I clicked the button and iTunes proceeded to encode the files, write the old database information to them , and then move the older files to the Trash.


The only problem with “Replace Existing” is that the option is only made available when the tag info of the CD and the tag info of the tracks being replaced is identical. Given that most users change CDDB’s data to edit for accuracy or to suit their particular needs, this means that often, a user will insert a CD, click “Import” and not be offered the option.

Thankfully, there are ways to remedy this problem. The simplest method is to insert the CD, get the track info from CDDB, and edit the CD’s tags as needed.  iTunes will allow you to edit disc-wide tag info from the Sources window. Click on the CD’s icon while holding down the “control” key. a contextual menu will appear which offers a “Get Info” option. Selecting this will result in a window containing the CD’s info, all of which is editable.



This same method works for getting the info of individual tracks.



Of course, with 9500+ songs to re-encode, I quickly lost patience with this method, as easy as it is, and I began looking for a quicker solution. I turned to AppleScript, and wrote a script which automates the compare and change process (available here for download). Now, I can insert the CD, batch-select the files I’m replacing, and run the script, making the task that much quicker.  (Note: the AppleScript isn’t perfect - if you use it, make sure you double-check the CD track info before encoding. CDSelecting “Advanced:Get CD Track Names” will re-write the CDDB info to the CD. The script also won’t work if the album in your iTunes Library doesn’t have the same number of tracks as the CD.)

If, for some reason, you change your tag info and on clicking “Import”. you are not given the “Replace Existing” option, do not despair. Remember that your old files are still on your computer, so before you remove them from your Library, find out if the songs are in any playlists. You can get this information the same way you got the track info: hold down “control” and click on the song. If the song is in any playlists, a “Playlists” contextual menu item will appear. Selecting it will show you which playlists include the song in question. Having found this out, you’ll want to add the new version of the track to the playlist and put it above or below the old on in the playlist queue.
The best means of doing this is to set your view mode to “Browse” (“Edit:Show Browser” or type “command-b”) .


In the Browser, select the artist and album you’re working on. In the tracks panel of the main browser window, you’ll see that both the AAC and mp3 files are displayed. Sorting by “Kind” will separate them. From there, it should be simple to work with your tracks and playlists.
Once you’ve got your playlist info squared away, make sure you compare the ratings and comments of each track. Having done this, it should be safe to delete the old files. You’ll lose play counts, but other than that, your metadata will be identical.

Working With Libraries in Multiple Locations

One of the downsides of my behemoth music library is the stricture of space. When I initially encoded my files, I was on a PowerBook G3 with a pitifully small hard drive. I bought an 40 GB external hard drive, which sufficed, for a time,  but by the time I upgraded to my current G4 iMac, my collection had grown beyond the hard drive’s capacity. Thus, I currently have 60 GB of music in two locations; most o f it residing on the external drive, and the rest on my iMac’s hard drive.
iTunes will only recognize one folder/location as its default Library location.  The default Library is where iTunes writes files it encodes. This is not an issue for normal operation of iTunes, but obviously, if I’m re-encoding files, iTunes will want to put every new file in its default Library , regardless of its initial location.

iTunes will, of course, allow you to change the location of your music folder. This is done quite easily under the Advanced tab of your iTunes Preferences. Changing the music library location is as simple as clicking “Change”.


So, armed with stacks of CDs, my solution is to organize the discs into two basic piles, corresponding to which drive they currently “live” on. Then pick the pile of music that “lives” wherever your default Library is currently set to, and start encoding. Once you’ve completed that stack, change the Library location, and encode those discs.

The main advantage of AAC over mp3 is overall smaller file size without quality loss, which means that, when you’re done encoding, you’ll have extra room in both spots. You may want to migrate files from one location to another. In my case, I’ll want to fill up the external hard drive, freeing up room on my iMac’s hard drive. But I won’t want iTunes database to “lose” the files. So, I’ll close iTunes, copy the files, open it, and change its Library location to the external drive. iTunes will update its song locations. Then I can change the Library location back, and it’ll update song locations again, resulting in my Library set to the correct folder and my songs all accounted for.

The Best Insurance Policy

Once you’re all done, I cannot recommend making backups enough.  iTunes 4 will make backups to DVD-R ( if you have a Super Drive) or CD-R, but either way, the best way to ensure you don’t have re-rip your CDs before a new, better codec is released is to get the tracks the way you want them and then burn those babies to a CD or DVD.

You should also periodically back up your iTunes Library File. This file is the database that contains all the track information about your songs. Backing this up is as simple as highlighting it in the Finder and selecting File:Duplicate. Should your Library file become corrupted, you have a backup with your playlists and metadata ready to replace it.

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I’m going through a similar process now.  A few observations:

9500 songs?

Posted by Andrew Giddings in Yellow Springs. OH on May 17, 2003 at 1:28 PM (CDT)


There is another option.  If you are like me and aren’t that particular about the difference between MP3 and AAC quality, you can use Ovolab’s (http://www.ovolab.com) AAChoo utility.

From their website:

An amazing utility for every music lover, Ovolab AAChoo converts all your MP3 songs to AAC, the new high-quality and compact audio format at the core of MPEG-4, with an easy drag-and-drop interface and full control over every encoding parameter.

Try that out !!

Posted by A G4 Cube User in Yellow Springs. OH on May 18, 2003 at 5:21 PM (CDT)


DON’T USE Ovolab AAChoo!
Frequent crashes are bad, as is the wiping of ID3 tags in many cases.

Don’t waste your time.

Posted by mc in Yellow Springs. OH on May 19, 2003 at 2:27 PM (CDT)


Ovolab AAChoo doesn’t do anything that iTunes doesn’t also do. Why pay extra money for functionality iTunes already has? A phrase from a Buddhist parable comes to mind:

Selling water by the river.

Posted by eustacescrubb in Yellow Springs. OH on May 19, 2003 at 2:52 PM (CDT)


Dude, you shouldn’t use AAChoo anyway.  Running two different codecs over the same song is a very bad idea because of severe audio degradation.  Not good.

Posted by Seth Johnson in Yellow Springs. OH on May 19, 2003 at 2:56 PM (CDT)


How about Windows XP, is there any apps can rip the CD direct to AAC ?


Posted by godzilla in Yellow Springs. OH on May 19, 2003 at 11:09 PM (CDT)


Get a Mac.

Why mess with XP?  I converted last November & never looked back.  I have 3 iBooks (very low cost) & a Powerbook in the house with an airport base station…. and I bout my wife an iPod with her iBook.  She loves it (& me for it).

Posted by Freddy in Yellow Springs. OH on May 20, 2003 at 12:51 AM (CDT)


If you do end up with duplicate tracks (1 AAC & 1 MP3) after reripping a CD theres a good way I use which enables you to preserve the play count, and any info thats stored in the iTunes library rather than the ID tags.

Do an an apple R to show your MP3 in the finder, and delete it (inc. emptying the trash). Then in iTunes, clear the AAC track (remove from library) by hitting backspace, and when it asks you if you want to move the track to the trash hit no. Then, Do a get info (or play) the MP3 track… it will say it can’t find it, do you want to locate it… then you just point it towards the AAC file and bingo…. play counts are preserved!

Posted by rees in Yellow Springs. OH on May 20, 2003 at 4:22 AM (CDT)


If you have edited a CD’s info because the CDDB info was wack, your Mac will keep in its cache the info you entered. iTunes will only look up CD info if you check the pref to always look up CD info on the net. Otherwise it will check its local cahe data and use that.

The downside is this won’t work if you have edited your track info AFTER ripping. However I’ve been in the habit of editing track info when the CD is still in the drive, that way, if I ever need to play the tracks from the CD the track info is to my liking. Perhaps more of a tip for future encoding…

Posted by monty in Yellow Springs. OH on May 20, 2003 at 4:39 AM (CDT)


If you’re looking for a little more control when ripping CDs as AAC, try Make Mine MPEG-4 (rip 10 CD demo, $7.00 thereafter). iTunes doesn’t let you set some of the encoding options in QuickTime, Audio Quality for example. Anecdotal evidence suggests that iTunes has it set at “Good” or “Normal”, but QT is capable of Better and Best. Further subjective listening tests suggest AACs ripped at 192 kbps at Best Audio Quality are superior to “plain-old” iTunes rips.


Posted by Doug Adams in Yellow Springs. OH on May 20, 2003 at 5:24 AM (CDT)


I have a couple questions regarding the new AAC format. As I understand it, if I convert MP3s to AAC the sound quality will degrade. Is this true? Therefore if the original was from a CD, I have to re-rip the CD. OK, I can do that. But what if the original was a downloaded file. Is converting a viable option or will I lose too much sound quality.

Also, I have now set up itunes to import as AAC. Therefore if I download a file, I assume its automatically being converted to AAC when I import into itunes. Does this degrade the sound?



Posted by davewe in Yellow Springs. OH on May 20, 2003 at 11:11 AM (CDT)


without getting the “stupid windows user. just switch” response… are there any info sources on AAC support and transferring to iPod on a PC (particularly windows XP and/or Linux).

i’m well aware of the fact that i should have a mac and believe me, if apple’d lower their goddam prices i’d have one. but i don’t (yet) so i gotta deal with windows and i’d like to do so with better AAC audio quality.

feel free to drop me an email at .(JavaScript must be enabled to view this email address) with any responses.

Posted by johnny duophone in Yellow Springs. OH on May 20, 2003 at 10:25 PM (CDT)


Dave Wrote:
if I convert MP3s to AAC the sound quality will degrade. Is this true?

Any time you compress something in a non-lossless format sound quality will degrade. I is like taking a piece of red paper and cutting it to fit a frame then realising you want to use a different frame. if you try to cut the piece of paper again it is still a red piece of paper just not as much.

Dave Wrote:
what if the original was a downloaded file. Is converting a viable option or will I lose too much sound quality.

“Too much” is relative if you don’t like it don’t convert if you think it is worth the time loss in quality and effort to you do it, but why convert when the ipod can play both one right after the other?

Dave Wrote:
Also, I have now set up itunes to import as AAC. Therefore if I download a file, I assume its automatically being converted to AAC when I import into itunes. Does this degrade the sound?

It will not automatically convert from one compressed format to another. you have set it to import from CD’s as AAC. If it were to convert it would degrade the sound to your ears.

Posted by Jim in Yellow Springs. OH on May 21, 2003 at 1:52 AM (CDT)


Is the new MMJB can rip the CD to AAC ?

Posted by godzilla in Yellow Springs. OH on May 22, 2003 at 2:21 AM (CDT)


I can’t wait for iTunes for Windows. Then I can get my wonderful iTunes interface at work (with windoze. :(((  )

Posted by Chris in Yellow Springs. OH on May 22, 2003 at 5:34 PM (CDT)


Rather than relying on perfect dupes of CDDB track info in order to use “Replace Existing,” why not manually delete the old tracks by using shift-arrow to highlight the tracks and delete them?

Not as elegant, but a lot faster—especially if you sort by Date Added and/or Format and then go through all the older tracks and kill ‘em off…..

Posted by libratem in Yellow Springs. OH on May 22, 2003 at 6:46 PM (CDT)


Because deleting the old tracks means losing the metadata, like ratings, play counts, comments, and it means losing songs from playlists.

Posted by eustacescrubb in Yellow Springs. OH on May 22, 2003 at 7:52 PM (CDT)


Let’s look past format wars into the future. Formats like AAC will come and go. How often do you feel like re-ripping your CDs?

Enough is enough. Rip to WAV and store permanent copies of your UNCOMPRESSED music. Hard drive space is cheap. Less than $1 a GB. Soon we will have 1TB drives.

Once you have all your music ripped to WAV, you can toss the aluminum for good and use those shelves for bamboo plants.

Every time a LATEST GREATEST new format comes along, you can just batch convert and put the archive hard drives away until next time (use external FireWire drives for convenience).

2 questions:

1) What is the best software to rip to WAV… I have used MusicMatch on the PC and it does CDDB lookup and names the file based on artist/album/song and even uses directories based on all that, which is nice. WAV files can’t store ID tags. Is there a better method?

2) What is the best software that converts WAV files to AAC (or the latest format)? I want to somehow preserve custom tag info for each track (complete with album graphics). I suppose I could store that in files in the directories with the songs, but it could get kind of messy.

Any suggestions?

Posted by Joey J in Yellow Springs. OH on May 25, 2003 at 7:32 AM (CDT)


Just a couple ideas:

If you re-rip a CD to AAC and for whatever reason, ‘Replace Existing’ doesn’t come up.  Just import anyway.  After it is done, browse to the album in iTunes.  Hit apple-J and enable the kind field.  Sort by Kind by clicking on the ‘Kind’ header and just delete the MPEG files.  You’ll have just AAC left.

Also use Smart Playlists to keep track of your ripping progress.  I have a Smart Playlist that keeps track of mp3’s not converted yet by using kind is ‘MPEG’ and date modified is before April.  I have a second Smart Playlist that keeps track of re-ripped AAC by using kind is ‘AAC’.  With live updating you can watch your progress by checking these playlists. 

Don’t rip your mp3’s to AAC.  Go back to the orginal CD.  If the mp3’s are downloaded, just deal with the fact that they are mp3’s.  I would only suggest re-ripping mp3’s if the original bit rate was at 256kbps or higher.  The only use for that would be to save a few megs of file size.  At that rate, you won’t lose that much quality if you go to AAC.  Please DO NOT re encode a 128 mp3 and expect any decent sound quality.

If you import any file supported by iTunes into iTunes it will remain at whatever format it was orginally.  iTunes will only convert format if you tell it to.

To manage WAV files:  I’ve never used it, but you may want to check out iView Media Manager http://www.iview-multimedia.com/  It may be what you are looking for.  I’m not sure.

Posted by Michael Hengeli in Yellow Springs. OH on May 25, 2003 at 7:29 PM (CDT)


I agree with comments made by Joey J. I have re-ripped several times with my latest discovery of the latest and greatest. I have settled on keeping copies of my CDs in .aiff format (uncompressed) and AAC versions of the same for my iPod.  I’ll keep the originals and batch convert should some other better compression come along.

Posted by Randy Decker in Yellow Springs. OH on May 25, 2003 at 10:29 PM (CDT)

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