MPEG-4 is a group of
international standards for the
compression of digital audio and visual data, multimedia systems, and file storage formats. It was originally introduced in late 1998 as a group of
audio and
video coding format
A video coding format (or sometimes video compression format) is a content representation format for storage or transmission of digital video content (such as in a data file or bitstream). It typically uses a standardized video compression alg ...
s and related technology agreed upon by the
ISO/
IEC Moving Picture Experts Group (MPEG) (
ISO/IEC JTC 1
ISO/IEC JTC 1, entitled "Information technology", is a joint technical committee (JTC) of the International Organization for Standardization (ISO) and the International Electrotechnical Commission (IEC). Its purpose is to develop, maintain and pr ...
/SC29/WG11) under the formal standard ISO/IEC 14496 – ''Coding of audio-visual objects''. Uses of MPEG-4 include compression of audiovisual data for
Internet video and
CD distribution, voice (
telephone
A telephone is a telecommunications device that permits two or more users to conduct a conversation when they are too far apart to be easily heard directly. A telephone converts sound, typically and most efficiently the human voice, into el ...
,
videophone) and
broadcast
Broadcasting is the distribution (business), distribution of sound, audio or video content to a dispersed audience via any electronic medium (communication), mass communications medium, but typically one using the electromagnetic spectrum (radio ...
television
Television, sometimes shortened to TV, is a telecommunication Media (communication), medium for transmitting moving images and sound. The term can refer to a television set, or the medium of Transmission (telecommunications), television tra ...
applications. The MPEG-4 standard was developed by a group led by Touradj Ebrahimi (later the
JPEG
JPEG ( ) is a commonly used method of lossy compression for digital images, particularly for those images produced by digital photography. The degree of compression can be adjusted, allowing a selectable tradeoff between storage size and im ...
president) and Fernando Pereira.
Background
MPEG-4 absorbs many of the features of
MPEG-1
MPEG-1 is a standard for lossy compression of video and audio. It is designed to compress VHS-quality raw digital video and CD audio down to about 1.5 Mbit/s (26:1 and 6:1 compression ratios respectively) without excessive quality loss, mak ...
and
MPEG-2
MPEG-2 (a.k.a. H.222/H.262 as was defined by the ITU) is a standard for "the generic coding of moving pictures and associated audio information". It describes a combination of lossy video compression and lossy audio data compression methods, w ...
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
Digital rights management (DRM) is the management of legal access to digital content. Various tools or technological protection measures (TPM) such as access control technologies can restrict the use of proprietary hardware and copyrighted work ...
and various types of interactivity.
AAC (Advanced Audio Coding) was standardized as an adjunct to MPEG-2 (as Part 1) before MPEG-4 was issued.
MPEG-4 is still an evolving standard and is divided into a number of parts. Companies promoting MPEG-4 compatibility do not always clearly state which "part" level compatibility they are referring to. The key parts to be aware of are
MPEG-4 Part 2
MPEG-4 Part 2, MPEG-4 Visual (formally ISO/ IEC 14496-2) is a video compression format developed by the Moving Picture Experts Group (MPEG). It belongs to the MPEG-4 ISO/IEC standards. It uses block-wise motion compensation and a discrete cosi ...
(including Advanced Simple Profile, used by codecs such as
DivX,
Xvid
Xvid (formerly "XviD") is a video codec library following the MPEG-4 video coding standard, specifically MPEG-4 Part 2 Advanced Simple Profile (ASP). It uses ASP features such as b-frames, global and quarter pixel motion compensation, lumi ma ...
,
Nero Digital and
3ivx
3ivx ( ) was an MPEG-4 compliant video codec suite, created by 3ivx Technologies, based in Sydney, Australia. 3ivx video codecs were released from 2001 to 2012, with releases of related technologies continuing until 2015. 3ivx provided plugins to ...
and by
QuickTime
QuickTime is an extensible multimedia framework developed by Apple Inc., capable of handling various formats of digital video, picture, sound, panoramic images, and interactivity. Created in 1991, the latest Mac version, QuickTime X, is a ...
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
High-definition video (HD video) is video of higher resolution and quality than standard-definition. While there is no standardized meaning for ''high-definition'', generally any video image with considerably more than 480 vertical scan lines ( ...
media like
Blu-ray Disc).
Most of the features included in MPEG-4 are left to individual developers to decide whether or not to implement. This means that there are probably no complete implementations of the entire MPEG-4 set of standards. 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.
Initially, MPEG-4 was aimed primarily at low-
bit-rate
In telecommunications and computing, bit rate (bitrate or as a variable ''R'') is the number of bits that are conveyed or processed per unit of time.
The bit rate is expressed in the unit bit per second (symbol: bit/s), often in conjunction w ...
video communications; however, its scope as a multimedia coding standard was later expanded. MPEG-4 is efficient across a variety of bit rates ranging from a few kilobits per second to tens of megabits per second. MPEG-4 provides the following functions:
* Improved coding efficiency over MPEG-2
* Ability to encode mixed media data (video, audio, speech)
* Error resilience to enable robust transmission
* Ability to interact with the audio-visual scene generated at the receiver
Overview
MPEG-4 provides a series of technologies for developers, for various service-providers and for end users:
* MPEG-4 enables different software and hardware developers to create multimedia objects possessing better abilities of adaptability and flexibility to improve the quality of such services and technologies as digital television,
animation graphics, the World Wide Web and their extensions.
* Data network providers can use MPEG-4 for data transparency. With the help of standard procedures, MPEG-4 data can be interpreted and transformed into other signal types compatible with any available network.
* The MPEG-4 format provides end users with a wide range of interaction with various animated objects.
* Standardized
Digital Rights Management
Digital rights management (DRM) is the management of legal access to digital content. Various tools or technological protection measures (TPM) such as access control technologies can restrict the use of proprietary hardware and copyrighted work ...
signaling, otherwise known in the MPEG community as Intellectual Property Management and Protection (IPMP).
The MPEG-4 format can perform various functions, among which might be the following:
*
Multiplexes
In telecommunications and computer networking, multiplexing (sometimes contracted to muxing) is a method by which multiple analog or digital signals are combined into one signal over a shared medium. The aim is to share a scarce resource - a ...
and
synchronizes data, associated with media objects, in such a way that they can be efficiently transported further via network channels.
* Interaction with the audio-visual scene, which is formed on the side of the receiver.
Profiles and Levels
MPEG-4 provides a large and rich set of tools for encoding.
Subsets of the MPEG-4 tool sets have been provided for use in specific applications.
These subsets, called 'Profiles', limit the size of the tool set a decoder is required to implement.
In order to restrict computational complexity, one or more 'Levels' are set for each Profile.
A Profile and Level combination allows:
[.]
* A codec builder to implement only the subset of the standard needed, while maintaining interworking with other MPEG-4 devices that implement the same combination.
* Checking whether MPEG-4 devices comply with the standard, referred to as
conformance testing.
MPEG-4 Parts
MPEG-4 consists of several standards—termed "parts"—including the following (each part covers a certain aspect of the whole specification):
Profiles are also defined within the individual "parts", so an implementation of a part is ordinarily not an implementation of an entire part.
MPEG-1
MPEG-1 is a standard for lossy compression of video and audio. It is designed to compress VHS-quality raw digital video and CD audio down to about 1.5 Mbit/s (26:1 and 6:1 compression ratios respectively) without excessive quality loss, mak ...
,
MPEG-2
MPEG-2 (a.k.a. H.222/H.262 as was defined by the ITU) is a standard for "the generic coding of moving pictures and associated audio information". It describes a combination of lossy video compression and lossy audio data compression methods, w ...
,
MPEG-7 and
MPEG-21 are other suites of MPEG standards.
MPEG-4 Levels
The low profile levels are part of the MPEG-4 video encoding/decoding constraints and are compatible with the older ITU H.261 standard, also compatible with former analog TV standards for broadcast and records (such as NTSC or PAL video). The ASP profile in its highest level is suitable for most usual DVD medias and players or for many online video sites, but not for Blu-ray records or online HD video contents.
More advanced profiles for HD media have been defined later in the AVC profile, which is functionally identical to the ITU H.264 standard but are now also integrated in MPEG-4 Part 10 (see
H.264/MPEG-4 AVC for the list of defined levels in this AVC profile).
Licensing
MPEG-4 contains patented technologies, the use of which requires licensing in countries that acknowledge
software algorithm patents. Over two dozen companies claim to have patents covering MPEG-4.
MPEG LA licenses patents required for MPEG-4 Part 2 Visual from a wide range of companies (audio is licensed separately) and lists all of its licensors and licensees on the site. New licenses for MPEG-4 System patents are under development
and no new licenses are being offered while holders of its old MPEG-4 Systems license are still covered under the terms of that license for the patents listed
MPEG LA – Patent List.
The majority of patents used for the MPEG-4 Visual format are held by three Japanese companies:
Mitsubishi Electric
, established on 15 January 1921, is a Japanese multinational electronics and electrical equipment manufacturing company headquartered in Tokyo, Japan. It is one of the core companies of Mitsubishi. The products from MELCO include elevators a ...
(255 patents),
Hitachi
() is a Japanese multinational corporation, multinational Conglomerate (company), conglomerate corporation headquartered in Chiyoda, Tokyo, Japan. It is the parent company of the Hitachi Group (''Hitachi Gurūpu'') and had formed part of the Ni ...
(206 patents), and
Panasonic
formerly between 1935 and 2008 and the first incarnation of between 2008 and 2022, is a major Japanese multinational conglomerate corporation, headquartered in Kadoma, Osaka. It was founded by Kōnosuke Matsushita in 1918 as a lightbulb ...
(200 patents).
See also
*
MPEG
The Moving Picture Experts Group (MPEG) is an alliance of working groups established jointly by ISO and IEC that sets standards for media coding, including compression coding of audio, video, graphics, and genomic data; and transmission and fi ...
*
MPEG-4 Structured Audio
*
MPEG-4 SLS
*
ISO/IEC JTC 1/SC 29
References
External links
MPEG-4 vs AVC/H.264 vs MP4. What is the difference?at the MPEG Official Website
*
*
JM MPEG-4 AVC /H.264 Reference CodeOpenIPMP: Open Source DRM Project for MPEG-4
{{DEFAULTSORT:Mpeg-4
Audio codecs
ISO/IEC standards
Video codecs
Videotelephony