Glossary definition of MPEG4

MPEG4 is a collection of methods defining compression of audio and visual (AV) digital data. It was introduced in late 1998 and designated a standard for a group of audio and video coding formats and related technology agreed upon by the ISO / IEC Moving Picture Experts Group (MPEG) under the formal standard ISO / IEC 14496. Uses of MPEG4 include compression of AV data for web (streaming media) and CD distribution, voice (telephone, videophone) and broadcast television applications.

MPEG4 absorbs many of the features of MPEG-1 and MPEG-2 and other related standards, adding new features such as (extended) VRML support for 3D rendering, object-oriented composite files (including audio, video and VRML objects), support for externally-specified Digital Rights Management and various types of interactivity. AAC (Advanced Audio Codec) was standardized as an adjunct to MPEG-2 (as Part 7) before MPEG4 was issued.

MPEG4 is still a developing standard and is divided into a number of parts. Companies promoting MPEG4 compatibility do not always clearly state which "part" level compatibility they are referring to. The key parts to be aware of are MPEG4 part 2 (including Advanced Simple Profile, used by codecs such as DivX, Xvid, Nero Digital and 3ivx and by Quicktime 6) and MPEG4 part 10 (MPEG4 AVC / H.264 or Advanced Video Coding, used by the x264 codec, by Nero Digital AVC, by Quicktime 7, and by next-gen DVD formats like HD DVD and Blu-ray Disc).

Most of the features included in MPEG4 are left to individual developers to decide whether to implement them. This means that there are probably no complete implementations of the entire MPEG4 set of standards. To deal with this, the standard includes the concept of "profiles" and "levels", allowing a specific set of capabilities to be defined in a manner appropriate for a subset of applications.

Initially, MPEG4 was aimed primarily at low bit-rate video communications; however, its scope was later expanded to be much more of a multimedia coding standard. MPEG4 is efficient across a variety of bit-rates ranging from a few kilobits per second to tens of megabits per second. MPEG4 provides the following functionalities:

Improved coding efficiency Ability to encode mixed media data (video, audio, speech) Error resilience to enable robust transmission Ability to interact with the audio-visual scene generated at the receiver