Debate about AAC and mp3

Most people - especially if using iTunes to play music on computer speakers or using standard headphones with an iDevice - won't be able to tell the difference between mp3/320 and aac/256. Forget the engineering analyses - let your ears make the decision. Personally I use aac/256 when extracting from CDs (more from habit rather than anything else) but purchase digital media from Amazon (aac) rather than the iTunes Store (mp3) - mainly for reasons of portability to non-Apple devices.

Overall, the perceptible difference between mp3/320 and aac/256 is far, far smaller than that between these and any lossless encoding ... and there are many combinations of recorded music and people's ears for which even that difference is insignificant.

It's entirely up to you - if mp3 or aac sound better to you then that's the way to go. If you compare the sound quality of CD playback vs. lossess vs. lossy and can hear an appreciable difference that you may want to adjust your approach. In general, CDs played on a hi-fi system will sound "better" than equivalent lossless files played on a computer (since hi-fi components are designed for this). Lossless playback will - for sources like well-recorded classical ,music or jazz - sound better that lossy MP3 or AAC. Popular music, particularly recent recordings or "remasters", is often mastered/compressed to just sound LOUD such that the advantages of lossless encoding are diminished.

If you do decide to pursue lossless within iTunes, I would avoid WAV as a format, primarily since this has no capability to embed metadata tags. Apple Lossless (ALAC) supports tagging as well as lossless compression giving files that are 40-50% the size of the corresponding WAV / AIFF (uncompressed PCM) files.

If you are going with a compressed format, it is mostly a matter of taste.

With the higher bit rates, I find the differences between MP3 and AAC to be subtle. I seem to hear a little more high frequency clarity with AAC than MP3..

They both cut out frequencies/sounds that sit behind the louder frequencies/sounds, that are present in a lossless format. For mixing and mastering, a lossless format is far better in my opinion. I cannot hear a noticeable difference between the differing lossless formats. In my opinion the headphones/speakers make more difference than the file format.

If the MP3 format sounds good to you, then that is all that matters.

The only time that I notice an appreciable difference in clarity and depth of sound is going from any lossless to any compressed file with a good pair of headphones or studio monitors.

Listening to an iPod/iphone through most earbuds/headphones, I doubt that most can hear much of a difference.

Choose what sounds best to you.

AIFF will just give you larger file sizes - there should be no audible difference between ALAC and AIFF. FLAC isn't supported in iTunes - although there are 3rd party add-ons that may add this capability, there will be no guarantee of compatibility with future releases of iTunes. It's been a while size I looked into these but AFAIR they enable playback within iTunes but don't support any sync operations with iDevices.

The various lossless formats (ALAC, FLAC, APE, SHN,, ...) use slightly different algorithms which explains variations in file size. Also, most offer variations in degree of compression which offer a playoff between file size and the processing needed for "real time" decompression. Since ALAC is optimized for iTunes there really aren't any significant reasons to use an alternative lossless format.

If I understand your needs correctly I'd suggest ripping your CDs to ALAC, using this as the standard format within your iTunes library, and making use of iTunes' capability to convert songs to a lower bit-rate (128k or 256k AAC) when syncing to your iPhone. This last part does make sync operations a little slower but does mean that you don't have to have two versions of every song in your library.

BTW (and as you may have guessed) I'm very dubious about claims about differences between audio formats that are based on theoretical analyses rather than simple use of the ears 😀

You're welcome!

You can rip all your CDs to iTunes in Apple Lossless format and have iTunes automatically convert them to AAC format when syncing them to an iPhone. This gives you the best of both worlds, you have the full lossless CD quality in iTunes and you have smaller files on the iPhone.

Note: This does not require having both Apple Lossless and AAC on your computer this process is done automatically during syncing - if you enable it.

It is possible to use Apple Lossless tracks in Windows Media Player as well should you need. This requires installing some additional free software for Windows XP, Vista, 7, or 8/8.1 but is now built-in as standard in Windows 10.

As a general comment most people would consider AAC at 256Kbps to be roughly equivalent to 320Kbps MP3 files. iTunes built-in MP3 encoder is not as far as I am aware based on either LAME or Fraunhofer but is written by Apple themselves. Being that MP3 is an official standard it is possible to use a separate program which does use LAME or Fraunhofer to rip your CDs and them import the resulting MP3 files in to iTunes.