The official title of MPEG-D is MPEG audio technologies. Unlike MPEG-C, MPEG-D parts 1, 2 and 3 actually specify audio codecs that are not generic as MPEG-1, MPEG-2 and MPEG-4 but intended to address specific application targets.

MPEG-D is composed of 5 parts, the first 4 of which are

1. Part 1 – MPEG Surround specifies an extremely efficient method for coding of multi-channel sound via the transmission of a 1) compressed stereo- or mono-audio program and 2) a low-rate side-information channel with the advantage of retaining backward compatibility to now ubiquitous stereo playback systems while giving the possibility to next-generation players to present a high-quality multi-channel surround experience
2. Part 2 – Spatial Audio Object Coding (SAOC) specifies an audio coding algorithm capable to efficiently handle individual audio objects (e.g. voices, instruments, ambience, ..) in an audio mix and to allow the listener to adjust the mix based on their personal taste, e.g. by changing the rendering configuration of the audio scene from stereo over surround to possibly binaural reproduction
3. Part 3 – Unified Speech and Audio Coding (USAC) specifies an audio coding algorithm capable to provide consistent quality for mixed speech and music content with a quality that is better than codecs that are optimized for either speech content or music content
4. Part 4 – Dynamic Range Control (DRC) specifies a unified and flexible format supporting comprehensive dynamic range and loudness control, addressing a wide range of use cases including media streaming and broadcast applications. The DRC metadata attached to the audio content can be applied during playback to enhance the user experience in scenarios such as ‘in a crowded room’ or ‘late at night’.