The Digital Entertainment Group (DEG), in cooperation with the Consumer Electronics Association (CEA) and The Recording Academy agreed on the creation of a formal definition for High Resolution Audio, in partnership with Sony Music Entertainment, Universal Music Group and Warner Music Group. The definition is accompanied by a series of descriptors for the Master Quality Recordings that are used to produce the hi-res files available to digital music retailers.

High Resolution Audio is defined as "lossless audio that is capable of reproducing the full range of sound from recordings that have been mastered from better than CD quality music sources."

In addition to this definition, four different Master Quality Recording categories have been designated, each of which describes a recording that has been made from the best quality music source currently available.

The descriptors for the Master Quality Recording categories are as follows:

MQ-P
From a PCM master source 48 kHz/20 bit or higher; (typically 96/24 or 192/24 content)

MQ-A
From an analog master source

MQ-C
From a CD master source (44.1 kHz/16 bit content)

MQ-D
From a DSD/DSF master source (typically 2.8 or 5.6 MHz content)