Home > Articles

  • Print
  • + Share This
This chapter is from the book

This chapter is from the book

1.3 MPEG Modus Operandi

MPEG is open to experts duly accredited by an appropriate National Standards Body. On average, a meeting is attended by more than 300 experts representing more than 200 companies, universities, and research centers spanning all industry domains with a stake in digital audio, video, and multimedia. On average, more than 20 countries are represented. The group meets three to five times a year. Participants in MPEG-4 include broadcasters, equipment and software manufacturers, digital content creators and managers, telecommunication service providers, and publishers and intellectual property rights managers, as well as university researchers.

MPEG held its first meeting in May 1988 in Ottawa (Canada) and reached its 58th meeting in December 2001 in Pattaya (Thailand). A Convener chairs the MPEG activities: Dr. Leonardo Chiariglione has been the MPEG Convener since the start of MPEG.

Because of its size, an MPEG plenary meeting can be a difficult experience for a newcomer if he or she has no guidance. MPEG meetings are well known for their openness, lively discussions, and detailed dissection of issues. During the meetings, MPEG is organized in several subgroups, each one with a chairman, notably these [N4500]:

  • Specification development subgroups: Systems, Video, Audio, Multimedia Description Schemes (MDS), and Synthetic Natural Hybrid Coding (SNHC)

  • Auxiliary subgroups: Requirements, Test, Implementation Studies, and Liaison

To better coordinate the work between the MPEG plenary meetings, MPEG may decide to establish ad hoc groups (AHG). AHGs are established with mandate, membership, chairman, duration, and meeting schedule at the end of an MPEG meeting, for the sole purpose of continuing work between MPEG meetings. They are established by MPEG and report to it; the task of an AHG may cover just preparation of recommendations to be submitted to MPEG, with no decisions made. The duration of an AHG usually is limited to the period between two successive MPEG meetings; AHGs always cease to exist at the start of an MPEG meeting. Participation in AHGs is not restricted to the delegates present at the meeting.

1.3.1 Mission

MPEG's area of work is the "development of international standards for compression, decompression, processing, and coded representation of moving pictures, audio, and their combination, in order to satisfy a wide variety of applications." [N4500]. According to the MPEG Terms of Reference [N4500], the MPEG Programme of Work is as follows:

  • Serve as responsible body within ISO/IEC for recommending a set of standards consistent with the area of work.

  • Cooperate with other standardization bodies dealing with similar applications. For this, MPEG creates liaisons with other standardization bodies as well as with other relevant duly constituted organizations (e.g., industrial consortia), exchanging requirements and technical specifications with the aim of reaching the largest possible use of standards.

  • Consider requirements for interworking with other applications, such as telecommunications and broadcasting, with other image coding algorithms defined by other SC29 Working Groups and with other picture and audio coding algorithms defined by other standardization bodies.

  • Define methods for the subjective quality assessment of audio, moving pictures, and their combination for the purpose of the area of work.

  • Assess characteristics of implementation technologies realizing coding algorithms of audio, moving pictures, and their combination.

  • Assess characteristics of digital storage and other delivery media, targets of the standards developed by WG11.

  • Develop standards for coding of moving pictures, audio, and their combination, taking into account the quality of coded media, effective implementation, and constraints from delivery media.

  • Propose standards for the coded representation of moving picture information.

  • Propose standards for the coded representation of audio information.

  • Propose standards for the coded representation of information consisting of moving pictures and audio in combination.

  • Propose standards for protocols associated with the coded representation of moving pictures, audio, and their combination.

1.3.2 Principles

Because the technological landscape changed from analog to digital, with all the associated implications, it was essential that standard makers acknowledged this change by modifying the way they create standards. Standards must offer interoperability across countries, services, and applications, and not just a system-driven approach by which the value of a standard is limited to a specific, vertically integrated system. This brings us to the toolbox approach by which a standard must provide a minimum set of relevant tools which (after they are assembled according to industry needs) provide the maximum interoperability at a minimum complexity—and very likely cost [Chia97]. The success of MPEG standards is based on this toolbox approach, bounded by the one functionality, one tool principle. In summary, MPEG wants to offer users interoperability and flexibility at the lowest complexity and cost.

To develop its standards, MPEG has been following a few principles. The most important of these principles, many of them very well known, are these [Chia97]:

  • Stick to the deadline: Because of the importance of allowing industries to make serious planning and investments based on timely standards, MPEG rigorously follows the workplan set at the beginning of each standardization project. Never has an MPEG standard been delayed in reaching IS status compared to the planned dates.

  • A priori standardization: To avoid becoming a standardization body endorsing industry-developed standards, MPEG identifies the maturity of technologies for standardization before industries make commitments. This approach allows the standard development process to be essentially technical and not biased by specific company interests.

  • Specify the minimum: In order that a standard might be useful to several industries (and not especially tuned for any of them), will technically evolve (increasing its lifetime), and will keep space for industrial competition, it is essential that only the minimum set of tools essential for interoperability is specified.

  • Not systems but tools: Because MPEG wants to specify standards that are useful for the various industries using the same technology, it is essential that tools rather than systems are specified, leaving the various industries the task of shaping those tools for their systems. To guide these industries, however, some major combinations of tools (profiling concept) are normatively specified so that functionality-driven and not application-driven combinations are adopted; this helps to increase interoperability and share costs.

  • One functionality, one tool: To reach interoperability with an acceptable level of complexity justifying industry investments, it is essential that clear choices be made regarding the best tool to provide a certain capability. Past experience has shown that the options epidemic (often engaged to satisfy companies' wishes) prevents interoperability, many times preventing the standards from flying and thus destroying everybody's work.

  • Relocation of tools/algorithms: So that the tools/algorithms are as useful as possible, not only must they be generic in the sense that they are not shaped to any specific application environment, it must also be possible to locate them at different positions in the final system, as different industries will likely position the same tool/algorithm differently (e.g., depending on the business model they follow).

  • Verification of the standard: To check that a standard delivers what it should deliver, it must be evaluated and checked against the identified requirements in the same way a product is checked against the product specification. This verification process typically involves the performance of subjective or task-based tests.

These principles have guided the development of the MPEG-1, MPEG-2, MPEG-4, and MPEG-7 standards with the same success, and they will be applied to the MPEG-21 standard development process.

1.3.3 Standards Development Approach

In MPEG, any standardization project is the result of an exploration attitude by which MPEG proactively looks for the relevant problems to be addressed—for example, emerging applications, functionalities, or even technologies. This proactive exploration attitude allows the standards to be produced in a timely way (and not too late) when applications and technology are fully mature as, by that time, proprietary solutions will be conquering the markets. For this purpose, MPEG holds open seminars to discuss relevant topics with people from industry and academia outside MPEG and creates ad hoc groups with the mandate to study the relevance in terms of standardization of specific topics.

After identifying a relevant area of interest, and in order to fulfill its objectives guided by the preceding principles, MPEG follows a standards development process with the following major steps [Chia97]:

  1. Applications: Identify relevant applications using input from MPEG members.

  2. Functionalities: Identify the functionalities needed by the applications.

  3. Requirements: Describe the requirements following from the functionalities so that common requirements can be identified for different applications.

  4. Common requirements: Identify which requirements are common across the areas of interest, and which are not common but still relevant.

  5. Specification: Specify the tools supporting the requirements in three phases.

    1. Call for proposals: A public call for proposals is issued, asking all interested parties to submit technology that is relevant to the identified requirements and functionalities.

    2. Proposal evaluation: The proposals are evaluated in a well-defined, adequate, and fair evaluation process, which is published with the call for proposals. The process can entail subjective testing, objective comparison, and evaluation by experts.

    3. Technical specification: As a result of the evaluation, the technology best addressing the requirements is selected; this technology typically does not correspond to a single proposal but to the set of the best tools extracted from all proposals. This is the start of a collaborative process to draft and improve the standard. The collaboration includes the definition and improvement of a working model, which embodies early versions of the standard and can include non-normative tools to better and more completely test the normative tools. The working model evolves through comparing different alternative tools with those already in the working model, through the so-called core experiments (CE).

  6. Verification: Verify that the tools developed can be used to assemble the target systems and to provide the desired functionalities with an adequate level of performance. This is done by means of verification tests. Until MPEG-4, the verification tests consisted of formal subjective tests aimed at evaluating the quality of either audio or video signals processed using specific MPEG algorithms; in MPEG-4, new types of tests have been performed [N999]. In order to obtain reliable and representative results, the tests are performed using optimized assessment methods and suitable panels of subjects.

This process is not rigid; some steps may be taken more than once and iterations are sometimes needed (as happened in MPEG-4). The time schedule, however, is always closely observed by MPEG. Although all decisions are made by consensus, the process keeps a fast pace, allowing MPEG to provide good technical solutions in a timely manner.

While the period until the proposals are evaluated is called the competitive phase, the period after the evaluation is the collaborative phase. During the collaborative phase, all the MPEG members collectively improve and complete the most promising tools identified at the proposals' evaluation. The collaborative phase is the major strength of the MPEG process, as hundreds of the top experts in the world, from many companies and universities, work together for a common goal. In this context, it does not come as a surprise that this superteam traditionally achieves excellent technical results, justifying the need for most companies to at least follow the process, if direct involvement is not possible.

Two working tools play a major role in the collaborative development phase that follows the initial competitive phase: the working model and core experiments [N1375]. In MPEG-1, the (video) working model was called Simulation Model (SM); in MPEG-2, the (video) working model was called Test Model (TM); and in MPEG-4, the various working models were called Verification Models (VMs).9 In MPEG-4, there were independent VMs for the video, audio, synthetic and natural hybrid coding (SNHC), and systems developments. Regarding the MPEG-4 VMs and CEs, it is important to highlight a few points [Pere99]. Verification Models

A VM is a complete framework defined in text and with a corresponding software implementation, such that an experiment performed by multiple independent parties will produce essentially identical results. VMs are enabled to check the relative performance of different tools, as well as to improve the performance of selected tools. The MPEG-4 VMs were built after screening the proposals. The first VM (for each technical area, e.g., video, audio, and SNHC) was not the best proposal but a combination of the best tools, independent of the proposal to which they belonged. Each VM included normative and non-normative tools to create the common framework that allowed performing adequate evaluation and comparison of tools targeting the continuous improvement of the technology included in the VM. After the first VMs were established, new tools were brought to MPEG-4 and evaluated within the VMs following a core experiment procedure. The VMs evolved through versions as CEs verified the inclusion of new techniques or proved that included techniques should be substituted. At each VM version, only the best performing tools were part of the VM. If any part of a proposal was selected for inclusion in the VM, the proposer had to provide the corresponding source code for integration into the VM software in the conditions specified by MPEG. Core Experiments

The improvement of the VMs started with a first set of CEs defined at the conclusion of proposal evaluation [N998]. The CE process allowed for multiple, independent, directly comparable experiments to determine whether a proposed tool had merit. Proposed tools targeted the substitution of a tool in one of the VMs or the direct inclusion in the VM to provide a new relevant functionality. Improvements and additions to the VMs were decided based on the results of CEs.

A CE must be completely and uniquely defined, so that the results are unambiguous. In addition to the specification of the tool to be evaluated, a CE also specifies the conditions to be used, again so the results can be compared. A CE is proposed by one or more MPEG experts and is accepted by consensus, providing that two or more independent experts agreed to perform the experiment.

It is important to realize that neither the text of the VMs nor any of the CEs ended (or will end) up in the standard itself, as they were just working tools to ease the development process. However the VMs' software is the basis for MPEG-4 Part 5: Reference Software [MPEG4-5] presented in the next section. Although it is not easy at this stage to tell how many CEs have been performed in MPEG-4, it is possible to state that they reached their goal by continuously improving and completing the technology to be included in the standard.

  • + Share This
  • 🔖 Save To Your Account

InformIT Promotional Mailings & Special Offers

I would like to receive exclusive offers and hear about products from InformIT and its family of brands. I can unsubscribe at any time.


Pearson Education, Inc., 221 River Street, Hoboken, New Jersey 07030, (Pearson) presents this site to provide information about products and services that can be purchased through this site.

This privacy notice provides an overview of our commitment to privacy and describes how we collect, protect, use and share personal information collected through this site. Please note that other Pearson websites and online products and services have their own separate privacy policies.

Collection and Use of Information

To conduct business and deliver products and services, Pearson collects and uses personal information in several ways in connection with this site, including:

Questions and Inquiries

For inquiries and questions, we collect the inquiry or question, together with name, contact details (email address, phone number and mailing address) and any other additional information voluntarily submitted to us through a Contact Us form or an email. We use this information to address the inquiry and respond to the question.

Online Store

For orders and purchases placed through our online store on this site, we collect order details, name, institution name and address (if applicable), email address, phone number, shipping and billing addresses, credit/debit card information, shipping options and any instructions. We use this information to complete transactions, fulfill orders, communicate with individuals placing orders or visiting the online store, and for related purposes.


Pearson may offer opportunities to provide feedback or participate in surveys, including surveys evaluating Pearson products, services or sites. Participation is voluntary. Pearson collects information requested in the survey questions and uses the information to evaluate, support, maintain and improve products, services or sites, develop new products and services, conduct educational research and for other purposes specified in the survey.

Contests and Drawings

Occasionally, we may sponsor a contest or drawing. Participation is optional. Pearson collects name, contact information and other information specified on the entry form for the contest or drawing to conduct the contest or drawing. Pearson may collect additional personal information from the winners of a contest or drawing in order to award the prize and for tax reporting purposes, as required by law.


If you have elected to receive email newsletters or promotional mailings and special offers but want to unsubscribe, simply email information@informit.com.

Service Announcements

On rare occasions it is necessary to send out a strictly service related announcement. For instance, if our service is temporarily suspended for maintenance we might send users an email. Generally, users may not opt-out of these communications, though they can deactivate their account information. However, these communications are not promotional in nature.

Customer Service

We communicate with users on a regular basis to provide requested services and in regard to issues relating to their account we reply via email or phone in accordance with the users' wishes when a user submits their information through our Contact Us form.

Other Collection and Use of Information

Application and System Logs

Pearson automatically collects log data to help ensure the delivery, availability and security of this site. Log data may include technical information about how a user or visitor connected to this site, such as browser type, type of computer/device, operating system, internet service provider and IP address. We use this information for support purposes and to monitor the health of the site, identify problems, improve service, detect unauthorized access and fraudulent activity, prevent and respond to security incidents and appropriately scale computing resources.

Web Analytics

Pearson may use third party web trend analytical services, including Google Analytics, to collect visitor information, such as IP addresses, browser types, referring pages, pages visited and time spent on a particular site. While these analytical services collect and report information on an anonymous basis, they may use cookies to gather web trend information. The information gathered may enable Pearson (but not the third party web trend services) to link information with application and system log data. Pearson uses this information for system administration and to identify problems, improve service, detect unauthorized access and fraudulent activity, prevent and respond to security incidents, appropriately scale computing resources and otherwise support and deliver this site and its services.

Cookies and Related Technologies

This site uses cookies and similar technologies to personalize content, measure traffic patterns, control security, track use and access of information on this site, and provide interest-based messages and advertising. Users can manage and block the use of cookies through their browser. Disabling or blocking certain cookies may limit the functionality of this site.

Do Not Track

This site currently does not respond to Do Not Track signals.


Pearson uses appropriate physical, administrative and technical security measures to protect personal information from unauthorized access, use and disclosure.


This site is not directed to children under the age of 13.


Pearson may send or direct marketing communications to users, provided that

  • Pearson will not use personal information collected or processed as a K-12 school service provider for the purpose of directed or targeted advertising.
  • Such marketing is consistent with applicable law and Pearson's legal obligations.
  • Pearson will not knowingly direct or send marketing communications to an individual who has expressed a preference not to receive marketing.
  • Where required by applicable law, express or implied consent to marketing exists and has not been withdrawn.

Pearson may provide personal information to a third party service provider on a restricted basis to provide marketing solely on behalf of Pearson or an affiliate or customer for whom Pearson is a service provider. Marketing preferences may be changed at any time.

Correcting/Updating Personal Information

If a user's personally identifiable information changes (such as your postal address or email address), we provide a way to correct or update that user's personal data provided to us. This can be done on the Account page. If a user no longer desires our service and desires to delete his or her account, please contact us at customer-service@informit.com and we will process the deletion of a user's account.


Users can always make an informed choice as to whether they should proceed with certain services offered by InformIT. If you choose to remove yourself from our mailing list(s) simply visit the following page and uncheck any communication you no longer want to receive: www.informit.com/u.aspx.

Sale of Personal Information

Pearson does not rent or sell personal information in exchange for any payment of money.

While Pearson does not sell personal information, as defined in Nevada law, Nevada residents may email a request for no sale of their personal information to NevadaDesignatedRequest@pearson.com.

Supplemental Privacy Statement for California Residents

California residents should read our Supplemental privacy statement for California residents in conjunction with this Privacy Notice. The Supplemental privacy statement for California residents explains Pearson's commitment to comply with California law and applies to personal information of California residents collected in connection with this site and the Services.

Sharing and Disclosure

Pearson may disclose personal information, as follows:

  • As required by law.
  • With the consent of the individual (or their parent, if the individual is a minor)
  • In response to a subpoena, court order or legal process, to the extent permitted or required by law
  • To protect the security and safety of individuals, data, assets and systems, consistent with applicable law
  • In connection the sale, joint venture or other transfer of some or all of its company or assets, subject to the provisions of this Privacy Notice
  • To investigate or address actual or suspected fraud or other illegal activities
  • To exercise its legal rights, including enforcement of the Terms of Use for this site or another contract
  • To affiliated Pearson companies and other companies and organizations who perform work for Pearson and are obligated to protect the privacy of personal information consistent with this Privacy Notice
  • To a school, organization, company or government agency, where Pearson collects or processes the personal information in a school setting or on behalf of such organization, company or government agency.


This web site contains links to other sites. Please be aware that we are not responsible for the privacy practices of such other sites. We encourage our users to be aware when they leave our site and to read the privacy statements of each and every web site that collects Personal Information. This privacy statement applies solely to information collected by this web site.

Requests and Contact

Please contact us about this Privacy Notice or if you have any requests or questions relating to the privacy of your personal information.

Changes to this Privacy Notice

We may revise this Privacy Notice through an updated posting. We will identify the effective date of the revision in the posting. Often, updates are made to provide greater clarity or to comply with changes in regulatory requirements. If the updates involve material changes to the collection, protection, use or disclosure of Personal Information, Pearson will provide notice of the change through a conspicuous notice on this site or other appropriate way. Continued use of the site after the effective date of a posted revision evidences acceptance. Please contact us if you have questions or concerns about the Privacy Notice or any objection to any revisions.

Last Update: November 17, 2020