How can I change file encoding for use in Itunes?

Question

For instance, aiff to apple lossles files, or mp3 to apple lossless, or any other conversion. And which is best?

Answer 1

I don't really understand some of the settings that you posted. Stereo and joint stereo are two different things, so you can't encode as both at the same time. For modern MP3 compression, joint stereo is usually preferred, because it allows the encoder to use fewer bits in encoding the stereo information, and it doesn't result in any perceptual losses in stereo imaging.
48.000 kHz is pointless unless you are ripping from source material that is actually at that sample rate. Redbook-standard CD audio is at 44.100 kHz, so just stick with that (or better yet, leave the sample rate setting at "auto" so it will pick the setting that matches the source material you are ripping from).
320 kbps is kind of overkill as well. Actually, if you want to rip to MP3, I would advise you to stay away from the iTunes encoder, because most listening tests indicate that it hasn't been updated much since the first versions of iTunes back in the late 1990s. It is no longer a modern encoder. Assuming that you are on a Mac, I suggest that you download the iTunes-LAME plugin (http://www.apple.com/downloads/macosx/ipod_itunes/ituneslameencoder.html), which allows you to encode tracks into the iTunes Music Library using the LAME MP3 encoder. LAME is an open-source encoder project that has been continuously developed over many years and has been heavily tested for transparency. The latest version (3.97b1) has been shown in listening tests to be almost the same quality as equivilent-bitrate AAC files.
Once you download the iTunes-LAME plug-in, you can install the latest version of LAME by going to http://www.rarewares.org/mp3.html . Scroll down to "Encoders/decoders built using LAME 3.97 beta 1" and download "For Mac OS X." This is a Unix Executable file. To install it in the iTunes-LAME plugin, go to Your User Folder/Library/iTunes/Scripts. Right click on the iTunes-LAME application and select "Show Package Contents." Open the "Contents" folder that appears and then open the "Resources" folder. You should see a Unix Executable there titled "lame." Replace this file with the 3.97b1 Unix Executable that you downloaded. Now iTunes-LAME will encode with LAME v.3.97b1 instead of its default LAME build. 3.97b1 has some major improvements over earlier LAME versions, so even though this installation process may seem daunting for some people, it is well worth it.
To use iTunes-LAME, you first select a CD or playlist from the Source list (the left-hand column) in iTunes. You then click on the Script menu (the little script icon) and select "Import with LAME...". iTunes-LAME opens, showing you a command line and an Import button. LAME encoding options are selected using command-line switches. Fortunately, there are variable bit-rate (VBR) presets that have been heavily tested for transparency, so you don't really need to know anything about the command line options. Just type in "-V 2 --vbr-new," which is one of the most heavily-tested presets, and hit the Import button. This results in variable bit rate files that usually average out to between 170 and 240 kbps, depending on the complexity of the source. For more information on the presets, see http://wiki.hydrogenaudio.org/index.php?title=LAME#RecommendedEncoderSettings
The only major downside to using iTunes-LAME is that it cannot take advantage of iTunes' error correction option when ripping CDs. If you want error correction though, you can always just have iTunes rip to WAV first, and then convert those WAV files to MP3 using the iTunes-LAME plugin.
Feel free to ask any more questions.