Q&A: Is Apple Lossless audio compression perfect?

Q I read an article elsewhere suggesting that Apple Lossless audio compression is not ‘perfect’, recommending the use of XLD for more accurate ripping of music. Having started to rip my CD collection using Apple Lossless, I find this worrying, as I do not want reduced audio quality. Should I change ripping methods?

A When correctly encoded and decoded, Apple Lossless (ALAC or ALE) audio format is truly lossless, in that it will reproduce bit-for-bit the original. It is thus a safe format for you and others seeking perfect reproduction, although there have been claims that some real-time decoding may not recreate the original audio perfectly. These were made on the basis of aural tests, and lack objectivity.

Whilst it is always possible to cut corners to make a real-time decoder perform better, but lose audio quality, this is untrue of QuickTime, given that Apple developed the format and made its source code open in 2011. Finally, XLD is not a CODEC in itself, but an audio tool that decodes and transcodes a range of lossless formats, including Apple Lossless. It would be naive to believe on the basis of aural evidence that it produced superior audio using its own CODEC.

Updated from the original, which was first published in MacUser volume 26 issue 24, 2010.