compressing audio files

[th1rt3en]

I have my music collection on itunes as full bandwidth aiff. Anyone have any suggestions as to how I can compress the files I have so I can fit more of my collection on my ipod? Will itunes let me reimport the music I already have using a different encoder?

[fracai]

Assuming you don't want to go to aac (lossy compression, but probably around 40x compression) you should use Apple Lossless (around 2x compression). There are other lossless formats like shn and flac (the most popular, free, open source). Apple Lossless will be the easiest for you as it's already installed and you can convert right in iTunes. You'll end up with duplicate files, but if you convert everything you should be able to sort by type and delete the aiff.

If you don't care about lossless compression, go for AAC and you'll have plenty of room.

[EatsWithFingers]

Will itunes let me reimport the music I already have using a different encoder?

In a word, yes. Existing tracks will only be replaced if the same encoder is used (even if the bitrate, etc. is different). This can be done from within iTunes itself:

Select the encoder you want to use (in Preferences-->Advanced-->Importing)
Select the tracks you want to convert
Choose "Convert Selection to <CODEC>" from the Advanced menu
Go away and do something else while the tracks are converted


My library has two copies of each song - one in AIFF and one in AAC. The former are stored on an external drive and used for playing through my home stereo, and the latter are stored on my laptop and synced with my iPod.

There are a few issues however:

Playcounts, etc. are not combined for the two file-types. That is, playing an AAC file will increment its playcount, and not the playcount of the equivalent AIFF file. This is because iTunes does not consider them to be the "same song".
The top-level "Music" playlist will contain both copies of each song. You'll probably want to have smart playlists to separate the two file types.
Keeping the track metadata the same across the two file types can be a right pain.


It would be much better if iTunes supported multiple file-formats for the same track, and thus did all the ****-data housekeeping itself. But that's for a future update.... (hopefully!)

And since you're wanting to sync the tracks with your iPod, I would suggest using a codec that gives small file sizes, since larger files require more disk accesses, and will result in poorer battery life (the extra CPU processing required to play the compressed file will be less than the power saved by having fewer disk accesses).