INTERNATIONAL ORGANISATION FOR STANDARDISATION
ORGANISATION INTERNATIONALE DE NORMALISATION
ISO/IEC JTC1/SC29/WG11
CODING OF MOVING PICTURES AND AUDIO

ISO/IEC JTC1/SC29/WG11 N0269
MPEG92/657
London, 06 November 1992

MPEG Press Release

Executive Summary

Today at the British Standards Institute in London, the Moving Picture Experts Group (MPEG), working under the joint direction of the International Standards Organization (ISO) and the International Electro-technical Commission (IEC), concluded a week-long meeting with potentially far-reaching consequences for moving-picture-and-sound applications in virtually all consumer and commercial industries. MPEG is developing a suite of International audiovisual encoding Standards which will enable traditionally distinct industries in computing, telecommunications, entertainment, and broadcast television (including cable and satellite operators)  to exchange moving-picture-and-sound data in ways never before possible, and to reduce the cost of important new applications through economies of scale.

These Standards  will enhance the quality of both traditional services such as broadcast, cable, and satellite TV delivery and new interactive and personalized services such as video-phones, movies-on-demand, catalog-shopping, and virtual-reality games. To ensure that a harmonized solution to the widest range of applications is achieved, MPEG is working jointly in the current phase of work with the CCITT Study Group XV "Experts Group on Video Coding for ATM Networks", which is responsible for video coding for future Broadband networks.

This week in London, MPEG completed its first phase of standards, MPEG-1, which will be used to store programs with video quality comparable to VCRs and audio quality comparable to audio CDs, on an inexpensive Compact Disc, enabling interactive multimedia applications.  Additionally, MPEG made substantial progress on its second phase of standards, MPEG-2, which will both enable audiovisual quality ranging from today's top-of-the-line consumer TVs to tomorrow's theater-like High-Definition TVs and provide the flexibility needed to support exotic new interactive applications.  The earliest industry implementations of MPEG-2 are expected to appear in mid-late 1993.  Finally, MPEG this week inaugurated future work in audiovisual coding at very low bit-rates, work which is expected to enable a number of new audiovisual applications by the mid 1990s.

General

A far-ranging variety of applications based on digital communications and storage technologies will benefit from the ability to present synchronized moving pictures and audio. Such communications-based applications include video-telephone, video-conferencing, cable, satellite and terrestrial broadcast TV distribution, and remote surveillance. Storage-based audiovisual applications include training, education, entertainment, advertising, video mail, and document annotation. Recent developments in the technology of digital storage media, image displays, desktop computing, communications networks and particularly in integrated circuits and data compression  have made digital video and audio economically viable for such applications. To facilitate the widest possible interchange of digitally encoded audiovisual programs and data, there is an urgent need to develop and promote the wide use of international standards for the coding method and format of digital video and audio data.

To respond to this need, the Moving Picture Experts Group (MPEG), just completing a week-long meeting today in London, has been convened as a Working Group under the joint supervision of the ISO and the IEC, two of the world's most influential International Standards organizations.  (The complete formal designation of MPEG is ISO/IEC JTC 1/SC 29/WG 11.)  The mandate under which MPEG operates is development of standards for coded representation of moving pictures, associated audio and their combination.

Organizations representing every aspect of the audiovisual industry, as well as academic and other institutions, have participated in MPEG through their national standards organizations.  Participating countries including Australia, Belgium, Brazil, Switzerland, Germany, France, United Kingdom, Italy, Israel, Japan, Korea, the Netherlands, Norway, Singapore, Sweden, Finland, and the USA.

MPEG's initial effort was development of the MPEG-1 coding standard.  Supporting target bit-rates of around 1.2 Mbit/s for video and 250 kbit/s for 2-channel stereo audio, MPEG-1 aimed at digital storage media such as Compact Disks.  Over the past year, target-bit-rate MPEG-1 implementations have demonstrated video quality comparable to today's consumer VCRs and audio quality comparable to today's audio Compact Discs.

While MPEG-1 provides impressive audiovisual quality at not only its target bit-rate, but at other bit-rates as well, it was determined that a new  standardization effort  MPEG-2  would best address some important features which had not been the focus of MPEG-1.  These include increased image quality in ranges from about 3 to 15 Mbit/s, support for interlaced video formats, and provision for multi-resolution scalability. New audio features include encoding of multi-channel audio and very-low bit rate stereo audio. The development of MPEG-2 was begun in 1991.  Since then, remarkably good performance has been achieved, and an MPEG-2 Commitee Draft is expected in 1993.

MPEG is working jointly with the CCITT SG XV "Experts Group on ATM Video Coding" in this new phase of work. The CCITT Experts Group will define video coding systems for use in broadband cell-based telecommunications networks. Close collaboration between the MPEG and the CCITT video coding group is aimed at providing a common solution and will ensure maximum applicability of the final standard.

In 1992, work directed toward coding at very-low bit-rates, several tens of kilobits per second, was initiated under the name MPEG-4.  (Original plans for MPEG-3 were incorporated into MPEG-2.) The MPEG-4 process is intended to become an official work item under ISO in the near future.

MPEG conducts liaison exchanges with CCITT, CCIR, and other relevant standards agencies.

MPEG-1

Status

At the WG11 (MPEG) meeting concluded today in London, minor editorial modifications were made to the first three parts of the ISO MPEG-1 Draft International Standard (DIS), entitled “Coding of moving pictures and associated audio for digital storage media at up to about 1.5 Mbit/s”. These first three parts of the MPEG-1 standard Systems (ISO IS 11172-1), Video (ISO IS 11172-2), and Audio (ISO IS 11172-3)  have now been forwarded to the ISO Central Secretariat for publication in 1994 as a final multi-part International Standard.

The fourth part of MPEG-1 (ISO 11172-4) will specify compliance testing for implementations of the first three parts.  By the close of this week's London meeting, Part 4 was progressed to the ISO Committee Draft (CD) level, the first of the two ISO draft document levels which undergo ballot by all participating national standards bodies.

Technical Content

Part 1, Systems: The MPEG-1 Systems specification provides for combining multiple coded audio and video streams into a single data stream. This coding specification includes information which enables decoding systems to keep audio and video streams fully synchronized, to access the data stream at random entry points, and to provide for future extensions. The basic principle of MPEG-1 Systems coding is the use of time stamps, which specify the decoding and display time of audio and video at a decoder in terms of a single system clock. It also provides for fully synchronized audio and video, and facilitates the storage in and the possible further transmission of the combined information through a variety of digital media.

 Part 2, Video: The MPEG-1 Video specification provides for compression of non-interlaced video. The applied compression algorithm is optimized for bitrates of about 1.2 Mbit/s, but it can perform very effectively over a wide range of bitrates and picture resolutions.  At a rate of 1.2 Mbit/s, good quality pictures have been demonstrated at 24, 25, and 30 frames/sec with a resolution comparable to VCRs.

 Part 3, Audio: The MPEG-1 Audio specification provides for audio compression.  The applied compression technique supports bitrates for stereo or dual channel programs from 64 kbit/s up to 448 kbit/s, covering a range from intermediate to compact disk quality.  The Audio specification also supports coding of a mono-channel, starting at a bit-rate of 32 kbit/s.  Depending on the application, three Layers, I, II, or III, of the coding system with increased complexity and performance can be used.  In Layer II, Compact Disc quality can be obtained for a stereo program at a total bit-rate of 192 kbit/s to 256 kbit/s.

Application Prospects

Many applications requiring digitally compressed video and audio are expected to apply the MPEG-1 standard.  Commercial and consumer systems already apply all three parts of the MPEG-1 standard, providing storage for pictures and/or audio on Compact Discs and cassettes for interactive video applications. It is anticipated that other applications, including multi-media desktop computing, video editing/production systems, and broadcasting systems, will utilize MPEG-1 as well.

MPEG-2

Title and Rationale

At its meeting concluded today in London, MPEG made substantial progress toward MPEG-2, its second phase of audiovisual standardization, entitled “Generic coding of moving pictures and associated audio”.  The general aim of MPEG-2 is to support a broad number of features and operating points which were not the focus of MPEG-1, and in so doing to establish an essentially generic, i.e. application independent standard, which will support a small number of key application profiles.

Requirements

MPEG-2 Video extends the capabilities of MPEG-1 with efficient methods to encode interlaced video formats. MPEG-2 Video key requirements include: optimized image quality in ranges from about 3 to 15 Mbit/s; support for various interlaced (as well as progressive) video formats; provision for multi-resolution bit-stream and decoder scalability; random accessibility to support efficient channel-hopping and editability; compatibility with both MPEG-1 and the CCITT H.261 recommendation for video telecommunications; adaptability to various transmission and storage channel-coding and error-recovery schemes; provision for low coding-decoding delay.

For MPEG-2 Audio, new features include support of 5-channel surround-sound plus low-frequency effect channel, multi-lingual audio, and stereo audio coding at rates below 64 kbit/s.

The aims of MPEG-2 Systems are to support these new audio and video formats in a manner extensible from the MPEG-1 Systems specification, and to enable multiplexing of multiple MPEG-1 Systems streams in support of multi-channel broadcast and new multimedia applications.

Workplan

For the Video work, a disciplined methodology has been established to enable experimentation on various modules of the video encoding and decoding system to proceed in parallel.  A video test model has been established, and several key modules in its algorithmic block diagram are subject to improvement up until March 1993.  For a proposed alternative to be selected to replace the current method, two independent

experts must confirm experimentally that the proposed method yields appreciably improved picture quality.  This methodology permits MPEG's dozens of experts from the world's top video coding laboratories to make tremendous improvements to the state-of-the-art over a remarkably short time. The MPEG-2 Audio and MPEG-2 Systems experts groups also employ similarly disciplined methodologies in the conduct of their work. In particular, the Audio group employs formal subjective audio-quality assessment procedure in its work.

A frozen technical specification for Video will be agreed upon by the end of the March 1993 meeting in Sydney, Australia. An MPEG-2 ISO Committee Draft is targeted for completion by the end of the November 1993 meeting.  This document will likely be a basis for early implementations by codec manufacturers.  Completion of the MPEG-2 ISO Draft International Standard  is scheduled for early 1994; this marks the point at which manufacturers may commit to production volumes.

Future Activities

Many exciting applications for digitally-encoded moving pictures and synchronized audio can be enabled only at very low bit-rates.  To address this need, the MPEG committee has inaugurated a process to develop a new international standard to be called MPEG-4, targeted at bit-rates of tens of kilobits and below.

Both communications-based and storage-based applications are envisioned.  The low bit-rates targeted by MPEG-4 are the operating points for wide-spread communications channels such as Public Switched Telephone Network (both modem and Integrated-Services Digital Network - ISDN) and low-cost wired and wireless networks. Such applications include video telephone, electronic video news, remote access to video data bases (e.g. videotex), and remote sensing and surveillance. Storage-based applications include games, annotation of electronic documents, deaf sign language captioning, and video mail.

The characteristics of these applications have been assessed to determine requirements for candidate algorithms, including cost, video and audio quality, delay, error robustness, and bit-rate. A need has been identified for both a near-term solution, based on extensions of existing algorithms, and a long-term solution, based on competitive development of new algorithms. There is a need for intensive work on these methods, and for identification of as-yet unknown new methods. The MPEG committee encourages researchers to develop algorithms capable of supporting very-low bit-rate audio-visual coding.