iTunes, iPod File Types & Quality

Last updated 05 March, 2006

I'm an iPod user and so are most of my friends. I often get questions related to this topic so I thought I would create a reference page to point people to...

About iTunes:

There are two main gripes with iTunes. The first is that the sound quality isn't what many (including myself) consider to be very good. The second is that they are DRM'd.

Music Quality:

For this page the term "music quality" refers to how the music sounds to you.

Songs purchased through the iTunes Music Store are encoded as 128kbps AAC files. AAC files normally have a .m4a file extension (i.e. U2 - Vertigo.m4a). However because Apple uses DRM to "protect" the files (more on this below), iTunes purchased songs have a .m4p extension.

So why the gripe over music quality?

First off let me state that "music quality" is subjective. It is influenced by the equipment you use to listen to it on, the type of music you listen to, how the music was recorded in the first place, and finally - your ear.

The gripe is that 128kbps is about as low as you go for music quality.

Some definitions before we continue:

(as they pertain to this page, I'm trying to make this a quick read and easy to understand so please don't whine at me if these aren't the strict definitions)

codec - The format in which music is is saved to your computer and/or iPod.

A codec can be either lossless (all information is retained, large file size) or lossy (information is compressed and/or stripped away, smaller file size).

This page will only discuss codecs that an iPod can play. They are (quoted from Apple): AAC (16 to 320 Kbps), Protected AAC (from iTunes Music Store), MP3 (16 to 320 Kbps), MP3 VBR, Audible (formats 2, 3 and 4), Apple Lossless, WAV, AIFF.

AAC - often referred to as "Apple Audio Codec" actually stands for "Advanced Audio Coding" (thanks Roger), .m4a file extension, lossy codec, considered by some to be an improvement over standard MP3.

Protected AAC - AAC with DRM, .m4p file extension, lossy codec,

MP3 - "MPEG Audio Layer 3", .mp3 file extension, lossy codec,  Probably the most widely used format.

MP3 VBR - MP3 using Variable Bit Rates, lossy codec,  Allows for better quality and smaller files.

Audible - Basically used for speech (audio books, etc.), .aa file extension. More info.

Apple Lossless - A little difficult to explain. It uses the same file extension (.m4a) as AAC (but it isn't AAC). Creates a larger file than AAC but retains more information/quality.

WAV - Short for Wave, .wav file extension, lossless codec. Basically it is the same as the file on your CD. "Original" sound quality, large file size.

AIFF - Audio Interchange File Format, .aiff file extension, lossless codec, usually used on Mac's, similar to WAV ("Original" sound quality, large file size).

encoding - The process of converting one file format to another. i.e. The file format on a CD you purchase is .cda, to transfer that song to you computer or iPod it must be encoded to another format (codec) like .mp3. The process of encoding is done by...wait for it...an encoder!

encoder - Encoders are usually part of another program (iTunes, Winamp, etc.)

DRM - short for Digital Rights Management. Nice name, only it restricts YOUR rights. Apple's iTunes Policy. More about DRM. If you do not like DRM there are 2 things you can do. 1 - Remove it. 2 - Stop using iTunes.

How do you remove DRM? - The only legal way I know of involves burning it to CD and then ripping it back to your hard drive. The method I use to backup my iTunes is here. There is a method to remove the DRM for songs purchased with earlier versions of iTunes (version 4.5 and earlier). I do not know if it is legal or not. See Hymn Project for more info.

So what codec should I use for my music?

Note - I'm automatically discounting WAV, AIFF, and Apple Lossless because in my opinion they are unnecessarily large files. I'm discounting the Audible format, because, well, it's a joke. That leaves us with the MP3 and AAC variants.

Oh boy, here we go...

The discussion of the "best" music codec is the subject of flame wars all over the net. So, I'm gonna start with a few explanations. When music is converted to any lossy codec it's quality is lessened (i.e. from CD to AAC). When you change/convert from one lossy codec to another the quality is lessened (i.e. AAC to MP3). You can never get that quality back. A file encoded at say MP3, 160kbps will never increase in quality.

An example:

If you purchased a song from iTunes it was protected AAC (.m4p), 128kbps. To "backup" the iTunes you burned it to CD (.cda). When you rip that song from the CD you will gain nothing by encoding it to anything greater than AAC, 128kbps. Many folks would say that is roughly equivalent to MP3, 160kbps.

So for songs purchased from iTunes use AAC, 128kbps or MP3, 160kbps. However if you want to maximize every ounce of quality, it is probably best to use AAC since that was the original format.

For songs not purchased from iTunes:

Again, you cannot increase the quality of a file once it has been saved to a lossy format. Leave it as is unless you want/need to decrease the file size.

Ripping from CD or getting music from another source (or, how I do it):

With the reminder that we cannot increase the music quality of a file already encoded in a lossy format...

When getting music from another source (or ripping from CD) I get songs that are MP3 codec encoded with the LAME(3.96.1) at 320kbps (constant bit rate). It should be noted that these files are rather large. Now for my 40GB iPod I couldn't care less how large it is, BUT, for my 4GB Nano I need to make these files smaller (yes, I have two versions of every file). I mainly use dBpowerAMP for my music conversion (the pay-for version). Now, I'm a tiny bit of a snob when it comes to quality of sound, that is, how it sounds to ME. So after experimenting with various compression settings I finally settled on 2 different settings:

For newer music:

Using a setting in dBpowerAMP called Alt Preset Standard (because this was as far down in quality as I was willing to go) for new files. This setting encodes VBR, LAME.

an example of output:

Saliva - Survival Of The Sickest(downsized).mp3   6.62 MB
Saliva - Survival Of The Sickest.mp3                     9.43 MB

For older songs (that weren't recorded from the greatest sources (by today's standards) in the first place):

Depending on the quality of the original file itself I'll use VBR, LAME with a minimum setting of 128 and a maximum setting of 160 or 192.

an example of output:

Beach Boys - Good Vibrations(downsized).mp3  3.38 MB
Beach Boys - Good Vibrations.mp3                    8.26 MB

What codec should you use?

Ugh! We are back to the beginning...Short answer, you are gonna have to decide for yourself.

If you are looking for my opinion (and that's all it is, one guys opinion), let's try and make a little checklist to help you decide:

(it should be noted I save everything in MP3 format)

1 - What is the highest level of audio equipment I'll ever play this on.

High - Very high-end home stereo

Medium - High-end car stereo, medium-end home stereo, high end computer speakers.

Low - Average computer speakers, boom-box, iPod headphones.

2 - File size

High - I've got plenty of hard drive space and/or I don't mind downsizing files if I need to.

Medium - I've got plenty of hard drive space but I want one file size.

Low - I want small file sizes.

3 - Quality

High - I'm an audio snob.

Medium - As long as it sounds good.

Low - I can't tell the difference between iTunes songs and the original music CD.

Take your highest answer,

If you answered:

High - MP3, or AAC @ 320kbps constant bit rate.

Medium - MP3 using Alt Preset Standard from above or AAC 192kbps.

Low - MP3 @ 160kbps or AAC @ 128kbps.

Hope this helps!