MPEG-4 Part 2


MPEG-4 Part 2, MPEG-4 Visual is a video compression format developed by the Moving Picture Experts Group. It belongs to the MPEG-4 ISO/IEC standards. It is a discrete cosine transform compression standard, similar to previous standards such as and H.262/MPEG-2 Part 2.
Several popular codecs including DivX, Xvid and Nero Digital implement this standard. Note that MPEG-4 Part 10 defines a different format from MPEG-4 Part 2 and should not be confused with it. MPEG-4 Part 10 is commonly referred to as H.264 or AVC, and was jointly developed by ITU-T and MPEG.
MPEG-4 Part 2 is H.263 compatible in the sense that a basic H.263 bitstream is correctly decoded by an MPEG-4 Video decoder. In MPEG-4 Visual, there are two types of video object layers: the video object layer that provides full MPEG-4 functionality, and a reduced functionality video object layer, the video object layer with short headers. MPEG-4 Part 2 is partially based on ITU-T H.263. The first MPEG-4 Video Verification Model used ITU-T H.263 coding tools together with shape coding.

History

The MPEG-4 Visual format was developed by the Moving Picture Experts Group committee. The specification was authored by Swiss-Iranian engineer Touradj Ebrahimi and Dutch engineer Caspar Horne. The standard was developed using patents from over a dozen organizations, listed by MPEG LA in a patent pool. The majority of patents used for the MPEG-4 Visual format were from three Japanese companies: Mitsubishi Electric, Hitachi, and Panasonic. See Patent holders below for a full list of patent holders.

Editions

Profiles

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. MPEG-4 Part 2 has approximately 21 profiles, including profiles called Simple, Advanced Simple, Main, Core, Advanced Coding Efficiency, Advanced Real Time Simple, etc. The most commonly deployed profiles are Advanced Simple and Simple, which is a subset of Advanced Simple.
Most of the video compression schemes standardize the bitstream leaving the encoder design to the individual implementations. Therefore, implementations for a particular profile are all technically identical on the decoder side. A point of comparison would be that an MP3 file can be played in any MP3 player, whether it was created through iTunes, Windows Media Player, LAME or the common Fraunhofer encoder.

Simple Profile (SP)

Simple Profile is mostly aimed for use in situations where low bit rate and low resolution are mandated by other conditions of the applications, like network bandwidth, device size etc. Examples are mobile phones, some low end video conferencing systems, electronic surveillance systems etc.

Advanced Simple Profile (ASP)

Advanced Simple Profile's notable technical features relative to the Simple Profile, which is roughly similar to H.263, include:
The MPEG quantization and interlace support are designed in basically similar ways to the way it is found in MPEG-2 Part 2. The B picture support is designed in a basically similar way to the way it is found in MPEG-2 Part 2 and H.263v2.
The quarter-pixel motion compensation feature of ASP was innovative, and was later also included in MPEG-4 Part 10 and VC-1. Some implementations omit support for this feature, because it has a significantly harmful effect on speed and it is not always beneficial for quality.
The global motion compensation feature is not actually supported in most implementations although the standard officially requires decoders to support it. Most encoders do not support it either, and some experts say that it does not ordinarily provide any benefit in compression. When used, ASP's global motion compensation has a large unfavorable impact on speed and adds considerable complexity to the implementation.

Simple Studio Profile (SStP)

The MPEG-4 Simple Studio Profile, or ISO/IEC 14496-2, has 6 levels going from SDTV to 4K resolution. MPEG-4 SStP allows for up to 12-bit bit depth and up to 4:4:4 chroma subsampling, using Intra-frame coding only. MPEG-4 SStP is used by HDCAM SR.
LevelMax bit depth and
chroma subsampling		Max resolution
and frame rate		Max data rate
110-bit 4:2:2SDTV180
210-bit 4:2:21920×1080 30p/30i600
312-bit 4:4:41920×1080 30p/30i900
412-bit 4:4:42K×2K 30p1,350
512-bit 4:4:44K×2K 30p1,800
612-bit 4:4:44K×2K 60p3,600

Patent holders

The following organizations hold patents for MPEG-4 Visual technology, as listed in the patent pool administered by MPEG LA.

OrganizationPatents
Mitsubishi Electric255
Hitachi206
Panasonic200
Sun Patent Trust125
Toshiba96
Samsung Electronics92
Sony84
Philips73
Sharp Corporation44
Pantech36
Robert Bosch GmbH27
Nippon Telegraph and Telephone24
GE Technology Development23
CIF Licensing20
Dolby19
Telenor19
Siemens AG15
JVC Kenwood14
Orange S.A.14
LG Electronics13
Fujitsu11
ZTE10
Google9
BT Group3
Calmare Therapeutics2
Cable Television Laboratories, Inc.1
Canon Inc.1
KDDI1
Microsoft1
Oki Electric Industry1
Sanyo1

Criticisms

MPEG-4 Part 2 has drawn some industry criticism. 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. Microsoft's Ben Waggoner states "Microsoft 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. I was involved in many digital media projects that wouldn't even touch MPEG-4 in the late 1990s to early 2000s because there was going to be a 'content fee' that hadn't been fully defined yet."

Popular software implementations