MPEG-4 is a group of

international standard international standard is a technical standard developed by one or more international standards organization, standards organizations. International standards are available for consideration and use worldwide. The most prominent such organization ...

s 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 Audio most commonly refers to sound, as it is transmitted in signal form. It may also refer to: Sound *Audio signal, an electrical representation of sound *Audio frequency, a frequency in the audio spectrum * Digital audio, representation of sou ...

and video coding formats and related technology agreed upon by the ISO/

IEC The International Electrotechnical Commission (IEC; in French: ''Commission électrotechnique internationale'') is an international standards organization that prepares and publishes international standards for all electrical, electronic and r ...

Moving Picture Experts Group (MPEG) ( ISO/IEC JTC 1/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 e ...

, videophone) and

broadcast Broadcasting is the distribution of audio or video content to a dispersed audience via any electronic mass communications medium, but typically one using the electromagnetic spectrum (radio waves), in a one-to-many model. Broadcasting began wi ...

television Television, sometimes shortened to TV, is a telecommunication medium for transmitting moving images and sound. The term can refer to a television set, or the medium of television transmission. Television is a mass medium for advertising, ...

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 imag ...

president) and Fernando Pereira.

Background

MPEG-4 absorbs many of the features of MPEG-1 and MPEG-2 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 m ...

Nero Digital Nero Digital is a brand name applied to a suite of MPEG-4-compatible video and audio compression codecs developed by Nero AG of Germany and Ateme of France. The audio codecs are integrated into the ''Nero Digital Audio+'' audio encoding tool for ...

and 3ivx and by QuickTime 6) and MPEG-4 part 10 (MPEG-4 AVC/ H.264 or Advanced Video Coding, used by the

x264 x264 is a free and open-source software library and a command-line utility developed by VideoLAN for encoding video streams into the H.264/MPEG-4 AVC video coding format. It is released under the terms of the GNU General Public License. Hi ...

encoder, Nero Digital AVC, QuickTime 7, and high-definition video media like

Blu-ray Disc The Blu-ray Disc (BD), often known simply as Blu-ray, is a digital optical disc data storage format. It was invented and developed in 2005 and released on June 20, 2006 worldwide. It is designed to supersede the DVD format, and capable of sto ...

). 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 ...

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 Animation is a method by which still figures are manipulated to appear as moving images. In traditional animation, images are drawn or painted by hand on transparent celluloid sheets to be photographed and exhibited on film. Today, most ani ...

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

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-2,

MPEG-7 MPEG-7 is a multimedia content description standard. It was standardized in ISO/IEC 15938 (Multimedia content description interface). This description will be associated with the content itself, to allow fast and efficient searching for material th ...

and

MPEG-21 The MPEG-21 standard, from the Moving Picture Experts Group, aims at defining an open framework for multimedia applications. MPEG-21 is ratified in the standards ISO/IEC 21000 - Multimedia framework (MPEG-21). MPEG-21 is based on two essential con ...

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 (255 patents),

Hitachi () is a Japanese multinational conglomerate corporation headquartered in Chiyoda, Tokyo, Japan. It is the parent company of the Hitachi Group (''Hitachi Gurūpu'') and had formed part of the Nissan ''zaibatsu'' and later DKB Group and Fuyo G ...

(206 patents), and Panasonic (200 patents).

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 Code

OpenIPMP: Open Source DRM Project for MPEG-4
{{DEFAULTSORT:Mpeg-4 Audio codecs ISO/IEC standards Video codecs Videotelephony