If you use iTunes to make MP3s, you’re not making the best sounding MP3s you could. It appears to me that the iTunes MP3 encoder is optimized for encoding speed, not sound quality. For better sound quality, use the newer AAC (M4A) format instead of MP3; but if you need to make MP3s for compatibility with older players (hardware or software), the iTunes MP3 encoder is not the best one to use. For low bit rates (below 128 kbps), the Fraunhofer MP3 encoder produces the best results; it’s used in some commercial software such as the Pro Tools MP3 Option.
For medium to high bit rates (roughly 128 kbps and above), the best sounding MP3 encoder in my comparisons (and other peoples’) is a popular free one called LAME. On Macs, there is a way to make MP3s in iTunes using LAME instead of the iTunes built-in MP3 encoder. It’s a free application called iTunes-LAME. Here are its download page and installation instructions.
The LAME encoder program in the iTunes-LAME package is fine, but it is not the newest version (as of this writing, iTunes-LAME comes with LAME 3.97, and the newest is 3.98.2). If you want to take advantage of more recent quality and speed improvements to LAME, you can get a newer version of LAME for MacOS X. Look for a listing like “LAME 3.98 for MacOS X: A universal binary which will run on both PowerPC and Intel powered Macs”. To install it, double-click its DMG file, and a window should open up showing two files, “lame” and “COPYING”. Next, right-click (or control-click) on the iTunes-LAME application and select “Show Package Contents”. Open up the Contents folder in the resulting window, and the Resources folder under that. Rename the existing “lame” file there to something like “lame original” in case you ever want to revert to it, then drag the new “lame” file into that Resources folder.
Or, if you really want to keep up with the latest version and are comfortable compiling programs, you can get the LAME source code. You’ll need to use a Terminal window to compile it (and you need the Apple XCode Tools installed), then install the new “lame” file as described earlier.
Once you have iTunes-LAME installed, when you run iTunes a scroll icon (signifying scripts) shows up in your iTunes menu bar, toward the right. Click on the scroll and select “Import with LAME…” from the drop-down menu. This brings up the iTunes-LAME window.
The iTunes-LAME encoding options are specified using a text box. For personal use to get the best sound quality, I type
--preset extreme (those are two dashes in a row before “preset”). If I want to use a particular bit rate, say 256 kbps, I type
--preset cbr 256. Some other good settings for various purposes are documented on audio forums.
LAME has way more options than most people would care about, but fortunately you can ignore most of them. When you see references to
--alt-preset, that’s just an older name for the
The iTunes-LAME Prefs button brings up a preferences window which includes the option of whether it should encode all the tracks in the current playlist that are checkmarked, or those that are highlighted (selected). Set it whichever way you find more convenient.
After you have entered in the LAME encoding settings, to make MP3s just select (or checkmark, depending on that setting) one or more tracks in iTunes and click the big round Import button on the iTunes-LAME window.