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

ISO/IEC JTC1/SC29/WG11

MPEG2005/N7645

Oct. 2005, Nice, FR

Title:               Description of MPEG-1 Conformance

Status:             Approved

Parts 1, 2 and 3 of ISO/IEC 11172 specify a multiplex structure and coded representations of audiovisual information. Parts 1, 2 and 3 of ISO/IEC 11172 allow for large flexibility, achieving suitability of this International Standard for many different applications. The flexibility is obtained by including parameters in the bitstream that define the characteristics of coded bitstreams. Examples are the audio sampling frequency, picture size, picture rate and bitrate parameters.  This part of ISO/IEC 11172 specifies how tests can be designed to verify whether bitstreams and decoders meet the requirements as specified in parts 1, 2 and 3 of ISO/IEC 11172. These tests can be used for various purposes such as:

• manufacturers of encoders, and their customers, can use the tests to verify whether the encoder produces valid bitstreams.
• manufacturers of decoders and their customers can use the tests to verify whether the decoder meets the requirements specified in parts 1,2 and 3 of ISO/IEC 11172 for the claimed decoder capabilities.
• applications can use the tests to verify whether the characteristics of a given bitstream meet the application requirements, for example whether the size of the coded picture does not exceed the maximum value allowed for the application.

This part of ISO/IEC 11172 specifies how tests can be designed to verify whether bitstreams and decoders meet requirements specified in parts 1, 2 and 3 of ISO/IEC 11172. In this part of ISO/IEC 11172, encoders are not addressed specifically. An encoder is entitled to be an ISO/IEC 11172 encoder if it generates bitstreams compliant with the syntactic and semantic bitstream requirements specified in parts 1, 2 and 3 of ISO/IEC 11172.

Characteristics of coded bitstreams and decoders are defined for parts 1, 2 and 3 of ISO/IEC 11172. The characteristics of a bitstream define the subset of the standard that is exploited in the bitstream. Examples are the applied values or range of the picture size and bitrate parameters. Decoder characteristics define the properties and capabilities of the applied decoding process. An example of a property is the applied arithmetic accuracy. The capabilities of a decoder specify which coded bitstreams the decoder can decode and reconstruct, by defining the subset of the standard that may be exploited in decodable bitstreams. A bitstream can be decoded by a decoder if the characteristics of the coded bitstream are within the subset of the standard specified by the decoder capabilities.

Procedures are described for testing compliance of bitstreams and decoders to the requirements defined in parts 1, 2 and 3 of ISO/IEC 11172. Given the set of characteristics claimed, the requirements that must be met are fully determined by parts 1, 2 and 3 of ISO/IEC 11172. This part of ISO/IEC 11172 summarizes the requirements, cross references them to characteristics, and defines how compliance with them can be tested. Guidelines are given how to construct tests and determine their outcome. Some actual tests are defined only for audio.