- MPEG-4 Part 2
MPEG-4 Part 2 is a
video compressiontechnology developed by MPEG. It belongs to the MPEG-4 ISO/ IECstandard (ISO/IEC 14496-2). It is a discrete cosine transformcompression standard, similar to previous standards such as MPEG-1and MPEG-2. Several popular codecs including DivX, Xvidand Nero Digitalare implementations of this standard. Note that MPEG-4 Part 10 defines a different format than MPEG-4 Part 2 and should not be confused with it. MPEG-4 Part 10is commonly referred to as H.264or AVC, and was jointly developed by ITU-Tand 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. 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 (and thus the decoder) leaving the encoder design to the individual implementations. Therefore, implementations for a particular profile (such as
DivXor Nero Digitalwhich are implementations of Advanced Simple Profile and Xvidthat implements both profiles) 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, LAMEor the common Fraunhofer encoder.
imple 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 cell phones, some low end video conferencing systems, surveillance systems etc.
Advanced Simple Profile (ASP)
Advanced Simple Profile 's notable technical features relative to the Simple Profile, which is roughly similar to
* Support for "MPEG"-style quantization
* Support for
* Support for
B pictures(a.k.a. "B Frames")
* Quarter Pixel
motion compensation( Qpel)
The MPEG quantization and interlace support are designed in basically similar ways to the way it is found in
MPEG-2Part 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 somewhat different forms) in
MPEG-4 Part 10and 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.
Despite being generally well received, MPEG-4 Part 2 has drawn some 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. [ [http://guru.multimedia.cx/?p=10 Lair Of The Multimedia Guru » 15 reasons why MPEG4 sucks ] ] 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. I was involved in many digital media projects that wouldn't even touch MPEG-4 in the late '90s to early '00s because there was going to be a 'content fee' that hadn't been fully defined yet." [ [http://forum.doom9.org/showthread.php?p=1026807#post1026807 VC-1 and H264 - Page 2 - Doom9's Forum ] ]
Popular software implementations
DivX(by DivX, Inc.)
* [http://www.m4if.org/resources/profiles/index.php Levels for MPEG-4 Visual Profiles]
Wikimedia Foundation. 2010.
Look at other dictionaries:
MPEG-4 Part 14 — (MP4) … Википедия
MPEG-4 Part 3 — MPEG 4 is a suite of standards which has many parts , where each part standardizes various entities related to multimedia, such as audio, video, and file formats. To know more about various parts and what they mean, please see the entry for MPEG… … Wikipedia
Mpeg-4 part 2 — ou MPEG 4 ASP (Advanced Simple Profile) est la partie 2 de la norme MPEG 4 pour la compression vidéo. Elle est utilisée entre autres par les codecs DivX 3 à 6 (propriétaire), et Xvid (sous licence GNU GPL). La partie 10 de la norme MPEG 4… … Wikipédia en Français
MPEG-4 Part 3 — Norme de compression audio. Développé par MPEG Type de format Compression audio. Extension du MPEG 4 Standard(s) ISO/IEC 14496 3 … Wikipédia en Français
MPEG-4 Part 11 — MPEG 4 is a suite of standards which has many parts , where each part standardizes various entities related to multimedia, such as audio, video, and file formats. To know more about various parts and what they mean, please see the entry for MPEG… … Wikipedia
MPEG-4 Part 14 — MPEG 4 Part 14, ou MP4, également appelé ISO/IEC 14496 14, est une partie de la norme MPEG 4 spécifiant un format conteneur pour encapsuler des données de type multimédia (audio ou vidéo essentiellement). L extension de nom de fichier… … Wikipédia en Français
MPEG-4 Part 20 — MPEG 4 Part 20, or MPEG 4 Lightweight Application Scene Representation (LASeR) is the new rich mediastandard dedicated to the mobile, embedded and consumer electronics industries specified by the MPEG standardization group.LASeR is based on SVG… … Wikipedia
MPEG-4 Part 17 — MPEG 4 is a suite of standards which has many parts , where each part standardizes various entities related to multimedia, such as audio, video, and file formats. To know more about various parts and what they mean, please see the entry for MPEG… … Wikipedia
MPEG-4 Part 2 — ou MPEG 4 Visual est la partie 2 de la norme MPEG 4 pour la compression vidéo. Elle est utilisée entre autres par les codecs DivX 3 à 6 (propriétaire), et Xvid (sous licence GNU GPL). Elle comprend deux profils : le Simple Profile (MPEG 4… … Wikipédia en Français
MPEG-2 Part 2 — (formally, ISO/IEC 13818 2) or H.262, is a video compression standard developed in a joint partnership between the ITU T and the ISO/IEC Moving Picture Experts Group organizations.It was approved in 1994 but in 1996 it was extended and was added… … Wikipedia