MPEG-4

Key takeaways

MPEG-4 belongs to science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect MPEG-4 to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of MPEG-4 from memory before moving on to harder problems.

Reference excerpt

MPEG-4 is a group of international standards 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 and video coding formats and related technology agreed upon by the ISO/IEC 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, videophone) and broadcast television applications. The MPEG-4 standard was developed by a group led by Touradj Ebrahimi (later the JPEG 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 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 (including Advanced Simple Profile, used by codecs such as DivX, Xvid, Nero Digital, RealMedia, 3ivx, H.263 and by QuickTime 6) and MPEG-4 part 10 (MPEG-4 AVC/H.264 or Advanced Video Coding, used by the x264 encoder, Nero Digital AVC, QuickTime 7, Flash Video, and high-definition video media like Blu-ray Disc). 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 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 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 digital rights management 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 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 and MPEG-21 are other suites of MPEG standards.

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. The majority of patents used for the MPEG-4 Visual format are held by three Japanese companies: Mitsubishi Electric (255 patents), Hitachi (206 patents), and Panasonic (200 patents).

See also MPEG MPEG-4 Structured Audio MPEG-4 SLS ISO/IEC JTC 1/SC 29

References

External links Overview of the MPEG-4 Standard Archived 2010-03-27 at the Wayback Machine at the MPEG Official Website Deprecated link at archive.today (archived 2012-10-22) MPEG Industry Forum (MPEGIF) MPEG-4 White Paper at the Library of Congress Web Archives (archived 2010-01-08) JM MPEG-4 AVC /H.264 Reference Code Archived 2015-08-02 at the Wayback Machine OpenIPMP: Open Source DRM Project for MPEG-4 Archived 2007-02-10 at the Wayback Machine

Worked examples

Example 1 — a first encounter with MPEG-4

Start with the simplest possible case. Write down what MPEG-4 claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to MPEG-4 before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about MPEG-4 ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of MPEG-4

In research: MPEG-4 appears in science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses MPEG-4 in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: MPEG-4 is common in secondary-school and first-year university syllabi. It links to neighbouring topics Audio codecs, ISO/IEC standards, MPEG-4, so understanding it makes those chapters shorter.
In everyday life: Look for MPEG-4 outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

How to study MPEG-4 in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what MPEG-4 means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain MPEG-4 out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is MPEG-4 in simple terms?

MPEG-4 is a group of international standards 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 and video coding formats and related technology agreed upon by the ISO/IEC Moving Picture Ex…

Why does MPEG-4 matter?

Because it connects several science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study MPEG-4?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on MPEG-4.