The Moving Picture Experts Group (MPEG) was formed by the ISO to set standards for audio and video compression and transmission. Its first meeting was in May 1988 in Ottawa, Canada. As of late 2005, MPEG has grown to include approximately 350 members per meeting from various industries, universities, and research institutions. MPEG's official designation is ISO/IEC JTC1/SC29 WG11.

Overview

The MPEG compression methodology is considered asymmetric in that the encoder is more complex than the decoder.John Watkinson, The MPEG Handbook, p.1 The encoder needs to be algorithmic or adaptive whereas the decoder is 'dumb' and carries out fixed actions. This is considered advantageous in applications such as broadcasting where the number of expensive complex encoders are small but the number of simple inexpensive decoders is large. This approach of the ISO to standardization in MPEG is considered novel because it is not the encoder which is standardized; instead, the way in which a decoder shall interpret the bitstream is defined. A decoder which can successfully interpret the bitstream is said to be compliant. The advantage of standardizing the decoder is that over time encoding algorithms can improve yet compliant decoders will continue to function with them. The MPEG standards give very little information regarding structure and operation of the encoder and implementers can supply encoders using proprietary algorithms.John Watkinson, The MPEG Handbook, p.2 This gives scope for competition between different encoder designs which means that better designs can evolve and users will have greater choice because of different levels of cost and complexity can exist in a range of coders yet a compliant decoder will operate with them all.

MPEG also standardizes the protocol and syntax under which it is possible to combine or multiplex audio data with video data to produce a digital equivalent of a television program. Many such programs can be multiplexed and MPEG defines the way in which such multiplexes can be created and transported. The definitions include the metadata used by decoders to demultiplex correctly.John Watkinson, The MPEG Handbook, p.3

Standards

The MPEG standards consist of different Parts. Each part covers a certain aspect of the whole specification. The standards also specifies Profiles and Levels. Profiles are intended to define a set of tools that are available, and Levels define the range of appropriate values for the properties associated with them. MPEG has standardized the following compression formats and ancillary standards:

• MPEG-1: is the first compression standard for audio and video. It was basically designed to allow moving pictures and sound to be encoded into the bitrate of a Compact Disc. To meet the low bit requirement, MPEG-1 downsamples the images, as well as using picture rates of only 24-30 Hz, resulting in a moderate quality. It includes the popular Layer 3 (MP3) audio compression format.