Fluid Mastering was the second studio in the UK to be recognised by Apple as an accredited supplier of masters for their Mastered For iTunes initiative, now rebranded as “Apple Digital Masters” (ADM).

The Apple Music app (and iTunes for PC users) now offers lossless streaming/downloads as well as AAC (* possibly a floating popup to explain AAC). For users listening to AAC streams and downloads, it’s preferable for the encoded file to have originated from a master which has been optimised for the format, which is where ADM comes in.

ADM mastering seeks to get the best possible results out of Apple’s internal AAC encoding process by using the highest available resolution in the master, whilst avoiding certain extremes which could produce undesirable side-effects in the encoded file.

Whilst you can put anything into a WAV file for download, an ADM/MFiT master has been checked and if necessary modified to ensure it meets Apple’s specifications as regards inter-sample clipping and sound quality. ADM files must be at 24 bit depth, and preferably at a higher sample rate than CD (44.1kHz). It is not acceptable to up-sample a 44.1kHz project to a higher rate, therefore higher sample rates should be used at the outset of a project if you want to supply an ADM master.

For the full strudel on Apple Digital Masters read their document.

*AAC popup/sidebar: AAC (standing for Advanced Audio Coding and denoted by the file extension .m4a) is a lossy audio codec which has been used by Apple since the earliest days of iTunes. It is broadly similar to the more well-known MP3 format, but with superior sound quality especially at lower bit rates. It is also used, although not exclusively and not at the same bit-rates, by most of the other well known platforms.