The MPEG standard

What is the evolution of standard documents ?

In chronological order:

The Proposal Stage
Voting members ballot on the creation of a new standards project.
The Preparatory Stage
Project Leader manages the development of a Working Draft.
The Committee Stage
Consensus is achieved on a Committee Draft.
The Approval Stage
National bodies vote on a Draft International Standard.
The Publication Stage
ISO publishes the International Standard.

MPEG is an ISO standard. It's exact name is ISO CD 11172. It consists of three parts: System, Video, and Audio. The System part (11172-1) deals with synchronization and multiplexing of audio-visual information, while the Video (11172-2) and Audio part (11172-3) address the video and the audio compression techniques respectively. Part 4, Conformance Testing, is currently a CD.

You will not find copies of the standard in the public domain, but you might want to check the Image Communication Information Board (ICIB), managed by the Fraunhofer Institute for Computer Graphics, that archives some parts of the MPEG documents.

From the Document Center WAIS server at wais.service.com we get :

Title							Pages	Price(US$)
-------------------------------------------------------	-----	----------
ISO/IEC-11172-1 - PART 1: SYSTEMS, INFORMATION		60	158.75
	TECHNOLOGY - CODING OF MOVING PICTURES &
	ASSOCIATED AUDIO FOR DIGITAL STORAGE

ISO/IEC-11172-2 - PART 2: VIDEO, INFORMATION TECHNOLOGY	122	204.00
	- CODING MOVING PICTURES & ASSOCIATED AUDIO FOR
	DIGITAL STORAGE

ISO/IEC-11172-3 - PART 3: AUDIO, INFORMATION TECHNOLOGY	157	214.25
	- CODING OF MOVING PICTURES & ASSOCIATED AUDIO
	FOR DIGITAL STORAGE

ISO/IEC-CD-11172 - INFORMATION TECHNOLOGY - CODING OF	-	207.00
	OF MOVING PICTURES & ASSOCIATED AUDIO - FOR
	DIGITAL STORAGE

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What are the important themes of MPEG ?

Application specific. MPEG does not solve everybody's application needs, but offers a syntax that is a good solution for most. MPEG does not, for example, decorrelate energies situated 1/256th of a pixel between a non-linear combination of 1000 frames. The syntax was designed to occupy an optimum between cost and quality. In other words, between computational complexity (VLSI area, memory size and bandwidth) and compaction (compression) efficiency.
The DCT and Huffman algorithms are some of the least significant aspects of the standard, and yet somehow receive the most press coverage.
In the encoding algorithm, you can do what you want as long as the bitstreams produced are compliant. There is a huge difference in picture quality between, for example, the test model and real-world propriety implementions of encoding.

How do you tell a MPEG-1 bitstream from a MPEG-2 bitstream ?

All MPEG-2 bitstreams must have certain extension headers that immediately follow MPEG-1 headers. At the highest layer, for example, the MPEG-1 style sequence_header() is followed by sequence_extension() which is exclusive to MPEG-2. Some extension headers are specific to MPEG-2 profiles.For example, sequence_scalable_extension() is not allowed in Main Profile

A simple program need only scan the coded bitstream for byte-aligned start codes to determine whether the stream is MPEG-1 or MPEG-2.