MPEG-4 Part 2

MPEG-4 Part 2, MPEG-4 Visual (formally ISO/IEC 14496-2[1]) is a video encoding specification designed by the Moving Picture Experts Group (MPEG).

To address various applications ranging from low-quality, low-resolution surveillance cameras to high definition TV broadcasting and DVDs, many video standards group features into profiles and levels.

Most of the video compression schemes standardize the bitstream (and thus the decoder) leaving the encoder design to the individual implementations.

The quarter-pixel motion compensation feature of ASP was innovative, and was later also included (in somewhat different forms) in later designs such as MPEG-4 Part 10, HEVC, VC-1 and VVC.

Some implementations of MPEG-4 Part 2 omit support for this feature, because it has a significantly harmful effect on the speed of software decoders and it is not always beneficial for quality.

When used, ASP's global motion compensation has a large unfavorable impact on speed and adds considerable complexity to the implementation.

FFmpeg's maintainer Michael Niedermayer has criticised MPEG-4 for lacking an in-loop deblocking filter, GMC being too computationally intensive, and OBMC being defined but not allowed in any profiles among other things.

[16] Microsoft's Ben Waggoner states "Microsoft (well before my time) went down the codec standard route before with MPEG-4 part 2, which turns out to be a profound disappointment across the industry - it didn't offer that much of a compression advantage over MPEG-2, and the protracted license agreement discussions scared off a lot of adoption.