Improved coding efficiency over MPEG-2.MPEG-4 is efficient across a variety of bit rates ranging from a few kilobits per second to tens of megabits per second. Initially, MPEG-4 was aimed primarily at low- bit-rate video communications however, its scope as a multimedia coding standard was later expanded. 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. This means that there are probably no complete implementations of the entire MPEG-4 set of standards. Most of the features included in MPEG-4 are left to individual developers to decide whether or not to implement. The key parts to be aware of are MPEG-4 Part 2 (including Advanced Simple Profile, used by codecs such as DivX, Xvid, Nero Digital and 3ivx and by QuickTime 6) and MPEG-4 part 10 (MPEG-4 AVC/ H.264 or Advanced Video Coding, used by the x264 encoder, Nero Digital AVC, QuickTime 7, and high-definition video media like Blu-ray Disc). Companies promoting MPEG-4 compatibility do not always clearly state which 'part' level compatibility they are referring to. MPEG-4 is still an evolving standard and is divided into a number of parts. AAC (Advanced Audio Coding) was standardized as an adjunct to MPEG-2 (as Part 7) before MPEG-4 was issued. MPEG-4 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.

Filme divx