Moving Picture Experts Group (MPEG

MPEG Video Webpage

The content of this page has been collected and updated to provide an overview on MPEG video group activities. It will give you, among others, information on past and recent activities in the MPEG video group, provide pointers to relevant web pages and some recent literature in the field. As MPEG in general is a dynamic and fast moving standardization body, some documents and related information may be outdated quickly. We will make every effort to keep up with the MPEG pace - however, keep in mind that this Webpage may not always contain the newest information.

MPEG in General

The Moving Picture Experts Group (MPEG) is a working group under ISO/IEC in charge of the development of international standards for compression, decompression, processing and coded representation of moving pictures, audio and their combination. So far MPEG has produced

MPEG-1: A standard for storage and retreival of moving pictures and associated audio on storage media

MPEG-2: A standard for digital televison

Two more standards are currently under development:

MPEG-4: A standard for multimedia applications

MPEG-7: A content representation standard for information search

MPEG ususally holds three meetings a year. These comprise plenary meetings and subgroup meetings on Requirements, Systems, Video, Audio, SNHC, Test, Implementation, DSM and Liason. MPEG meetings are attended by some 300 experts from some 20 countries.


The MPEG Video Group

Within MPEG the MPEG Video Group is the largest working group and has the mandate to develop and standardize video coding tools and algorithms. The MPEG video group meetings are usually attended by appr. 100-150 video experts from appr. 20 countries (Asia, Australia, North America, Europe). The MPEG video group has successfully completed and released the MPEG-1 video coding standard in 1992 and MPEG-2 video coding standard in 1994 and is currently in the process of finalizing the MPEG-4 video standard. The release of the MPEG-4 video coding international standard is targeted for July 1998.


How does the MPEG Video Group work

The Core Experiment Process - Verification Model Philosophy

Within the MPEG video group the video coding standards are developed based on a Verification Model (or Test Model) and an associated "Core Experiment" process.

The purpose of a Verification Model (VM) within MPEG is to describe completely defined encoding and decoding "Common Core" algorithms, such that collaborative experiments performed by multiple independent parties can produce identical results and will allow the conduction of "Core Experiments" under controlled conditions in a common environment.

A Verification Model (in MPEG-2 phase this was called "Test Model") is established at the beginning of a standardization phase based on the assesment of individual proposals submitted to the MPEG video group. It specifies the input and output formats for the uncoded data and the format of the bitstream containing the coded data. It specifies the algorithm for encoding and decoding, including the support for one or more functionalities. For the development of a MPEG Video standard the MPEG Video group establishes a number of "Core Experiments" to improve the efficiency of the MPEG-4 VM between meetings with respect to the functionalities already supported - and to identify new coding techniques that allow provisions for functionalities not yet supported by the VM. A Core Experiment is defined with respect to the Verification Model, which is considered as the Common Core algorithm. A Core Experiment proposal describes a potential algorithmic improvement to the VM, i.e. a motion compensation technique different to the one defined by the VM. Furthermore the full description of encoder and decoder implementation of the algorithm and the specification of experimental conditions (bit rates, test sequences, etc.) to compare the proposed Core Experiment technique against the performance of the VM are provided. A Core Experiment is being established by the MPEG Video group if two independent parties are committed to perform the experiment. If a Core Experiment is successful in improving on techniques described in the VM - i.e. in terms of coding efficiency, provisions for functionalities not supported by the VM and implementation complexity - the successful technique will be incorporated into the newest version of the VM. The technique will either replace an existing technique or supplement the algorithms supported by the VM.

Core Experiments are being performed between two MPEG Video group meetings. At each MPEG Video group meeting the results of the Core Experiments are being reviewed and the VM is updated depending on the outcome of the experiment and a new version of the VM is being released. Thus the VM progresses from one meeting to the next. The last version of the MPEG-2 Verification Model was Test Model 5 (TM 5) which formed the basis for the MPEG-2 video standard.


MPEG-1

In 1988 the Moving Picture Experts Group (MPEG) was founded under ISO/SC2 with the charter to standardize a video coding algorithm targeted for digital storage media and bit rates at up to about 1.5 Mbits/s. Its official denotation is now ISO/IEC/JTC1/SC29/WG11. The first Draft Iinternational Standard (DIS) released by the committee, ISO 11172 (MPEG-1), was drafted in 1991 and finally issued as IS in 1992. MPEG-1 is intended to be generic (although the initial target applications envisaged and applications parameters defined were constrained to digital storage media). Generic means, that the standard is independent of a particular application and therefore comprises mainly a toolbox. It is up to the user to decide, which tools to select to suit the particular applications envisaged. This implies, that only the coding syntax is defined and therefore mainly the decoding scheme is standardized. MPEG-1 defines a hybrid DCT/DPCM coding scheme with motion compensation similar to the H.261 and CCIR Rec. 723 coding standards. Further refinements in prediction and subsequent processing were introduced to provide the functionality required for random access in digital storage media.

MPEG-1 Overview

More on MPEG-1 and -2


MPEG-2

Studies on MPEG-2 started in 1990 with the initial target to issue a standard for coding of TV-pictures with CCIR Rec. 601 resolution at data rates below 10 Mbit/s. In 1992 the scope of MPEG-2 was enlarged to suit coding of HDTV - thus making an initially planned MPEG-3 phase superfluous. The DIS for MPEG-2 video was issued in early 1994.

The video coding scheme used in MPEG-2 is again generic and similar to the one of MPEG-1, however with further refinements and special consideration of interlaced sources. Furthermore many functionalities such as "scalability" were introduced. In order to keep implementation complexity low for products not requiring the full video input formats supported by the standard (e.g. SIF to HDTV resolutions), so called "Profiles", describing functionalities, and "Levels", describing resolutions, were introduced to provide separate MPEG-2 conformance levels.

MPEG-2 Overview

More on MPEG-1 and -2



The MPEG-4 Video Coding Standard

Anticipating the rapid convergence of telecommunications industries, computer and TV/film industries, the MPEG group officially initiated a new MPEG-4 standardization phase in 1994 - with the mandate to standardize algorithms and tools for coding and flexible representation of audio-visual data to meet the challenges of future Multimedia applications and applications requirements. In particular MPEG-4 addresses the need for

  • Universal accessibility and robustness in error prone environments - Multimedia audio-visual data need to be transmitted and accessed in heterogeneous network environments, possibly under severe error conditions (e.g. mobile channels). Although the MPEG-4 standards will be network (physical-layer) independent in nature, the algorithms and tools for coding audio-visual data need to be designed with awareness of network peculiarities.
  • High interactive functionality - Future Multimedia applications will call for extended interactive functionalities to assist the user's needs. In particular the flexible, highly interactive access to and manipulation of audio-visual data will be of prime importance. It is envisioned that - in addition to conventional playback of audio and video sequences - the user need to access "content" of audio-visual data to present and manipulate/store the data in a highly flexible way.
  • Coding of natural and synthetic data - Next generation graphics processors will enable Multimedia terminals to present both pixel based audio and video data together with synthetic audio/speech and video in a highly flexible way. MPEG-4 will assist the efficient and flexible coding and representation of both natural (pixel based) as well as synthetic data.
  • Compression efficiency - For the storage and transmission of audio-visual data a high coding efficiency, meaning a good quality of the reconstructed data, is required. Improved coding efficiency, in particular at very low bit rates below 64 kbits/s, continues to be an important functionality to be supported by the MPEG-4 video standard.

Bit rates targeted for the MPEG-4 video standard are between 5-64 kbits/s for mobile or PSTN video applications and up to 2 Mbits/s for TV/film applications. Seven new (with respect to existing or emerging standards) key video coding functionalities have been defined which support the MPEG-4 focus and which provide the main requirements for the work in the MPEG video group. The requirements cover the main topics related to "Content-Based Interactivity? "Compression?and "Universal Access? The release of the MPEG-4 International Standard is targeted for July 1998.


More on MPEG-4 Video


MPEG-7


MPEG-1 References:

J.L.Mitchell, W.B.Pennebaker, C.E.Fogg and D.J.LeGall, "MPEG Video Compression Standard", in Digital Multimedia Standards Series,Chapman & Hall, New York, NY, 1997.

D.J. Le Gall, "The MPEG Video Compression Algorithm", Signal Processing: Image Communication 4, No. 2, pp. 129-140, 1992

MPEG-2 References:

J.L.Mitchell, W.B.Pennebaker, C.E.Fogg and D.J.LeGall, "MPEG Video Compression Standard", in Digital Multimedia Standards Series,Chapman & Hall, New York, NY, 1997.

B. G. Haskell, A. Puri and A. N. Netravali, "Digital Video: An Introduction to MPEG-2," ISBN: 0-412-08411-2, Chapman & Hall, 1997.

Multifunctional Ad hoc Group, "Core experiments Description," ISO/IEC JTC1/SC29/WG11 N1266, March 1996.

Stereoscopic Video Coding

A. Puri, R. V. Kollarits and B. G. Haskell, "Basics of Stereo scopic Video, New Compression Results with MPEG-2 and a Proposal for MPEG-4," accepted for pub, Signal Processing: Image Communications.

A. Puri, R. V. Kollarits and B. G. Haskell, "Stereoscopic Video Compression Using Temporal Scalability," Proc. SPIE Visual Communications and Image Processing'95, Taiwan, May 1995.

A. Shigenaga and T. Homma, "Experimental Results of Coding of Stereo Sequences with Temporal Scalability," ISO/IEC JTC1/SC29/WG11 Doc. MPEG95/254, July 1995.

A. Puri and B. G. Haskell, "A Revised Proposal for Multiview Coding and Multiview Profile" ISO/IEC JTC1/SC29/WG11 MPEG95/249, July 1995.

A. Luthra and X. Chen, "MPEG-2 Multiview Profile for MPEG-2," to appear Proc. SPIE/IS&T Multimedia Hardware Architectures, EI'97, Feb. 1997.

MPEG-4 References:

L.Chiariglione, "MPEG and Multimedia Communications", IEEE Trans. CSVT, Vol.7, No.1, Feb.1997.

T.Sikora, "The MPEG-4 Video Standard Verification Model", IEEE Trans. CSVT, Vol.7, No.1, Feb.1997.

T.Sikora, "MPEG-4 Very Low Bit Rate Video ", Proc. IEEE ISCAS Conference, Hongkong, June 1997.

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