MPEG-4
MPEG-4 inherited many of the features in MPEG-1 and MPEG-2 and then added a rich
set of multimedia features such as discrete object encoding, scene description, rich
metadata, and digital rights management (DRM). Most applications support only a
subset of all the features available in MPEG-4.
Compared to MPEG-1 and MPEG-2, MPEG-4 video compression (known as MPEG-4 Part 2)
provides superior quality at low bit rates. However, MPEG-4 also supports high-resolution
video as well. For example, Sony HDCAM SR uses a form of MPEG-4 compression.
MPEG-4 Part 3 defines and enhances AAC audio originally defined in MPEG-2 Part 7.
Most applications today use the terms AAC audio and MPEG-4 audio interchangeably.