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information may be outdated quickly.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.
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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
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: , 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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