ISO/IEC 11172-4:1995

INTERNATIONAL
ISO/IEC
STANDARD 11172-4
First edition
1995-03-I 5
Information technology - Coding of
moving pictures and associated audio for
digital storage media at up to about
I,5 Mbit/s -
Part 4:
Compliance testing
Technologies de I’informa tion - Codage de /‘image animbe et du son
associ6 pour les supports de stockage numgrique jusqu% environ
1,5 Mbit/s -
Partie 4: Essais de conformit
Reference number
&O/I EC 11172-4: 1995(E)
lSO/IEC 11172-4: 1995 (E)
Contents Page
Foreword . iii
Introduction . iv
Section 1: General . 1
1.1 Scope . 1
1.2 Normative references . 1
Section 2: Technical elements 2
.................................................................
2.1 Definitions .
2.2 Symbols and abbreviations .
2.3 Bitstream characteristics .
2.4 Decoder characteristics . 16
2.5 Procedures to test bitstream compliance . 18
2.6 Procedures to test decoder compliance . 29
Annexes
A Definition of audio decoder tests . 31
B Descriptions of the ISO/IEC 11172 (MPEG) audio test bitstreams 3 2
0 ISO/IEC 1995
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ii
0 ISOAEC lSO/IEC 11172-4: 1995 (E)
Foreword
IS0 (the International Organization for Standardization) and IEC (the International Electrotechnical
Commission) form the specialized system for world-wide standardization. National Bodies that are members
of IS0 and IEC participate in the development of International Standards through technical committees
established by the respective organization to deal with particular fields of technical activity. IS0 and IEC
technical committees collaborate in fields of mutual interest. Other international organizations,
governmental and non-governmental, in liaison with IS0 and IEC, also take part in the work.
In the field of information technology, IS0 and IEC have established a joint technical committee, ISO/IEC
JTC 1. Draft International Standards adopted by the joint technical committee are circulated to national
bodies for voting. Publication as an International Standard requires approval by at least 75 % of the
national bodies casting a vote.
ISO/IEC 11172 consists of the following parts, under the general title Information technology - Coding of
moving pictures and associated audio for digital storage media at up to about 1,5 Mbit/s:
- Part I: Systems
- Part 2: Video
- Part 3: Audio
- Part 4: Compliance testing
Annex A forms an integral part of this part of ISO/IEC 11172. Annex B is for information only.
. . .
lSO/IEC 11172-4: 1995 (E) 0 ISOAEC
Introduction
This International Standard was prepared by ISO/IEC JTClISC29NVGll also known as MPEG (Moving
Pictures Expert Group). MPEG was formed in 1988 to establish an International Standard for the coded
representation of moving pictures and associated audio stored on digital storage media. Parts 1,2 and 3 of
this International Standard were unanimously approved by the participating National Bodies in November
1992.
This International Standard is published in four parts. Part 1 - Systems - specifies the system coding layer
of the standard. It defines a multiplexed structure for combining audio and video data and means of
representing the timing information needed to replay synchronized sequences in real-time. Part 2 - video -
specifies the coded representation of video data and the decoding process required to reconstruct pictures.
Part 3 - audio - specifies the coded representation of audio data and the decoding process required to
reconstruct audio. Part 4 - compliance testing - specifies procedures to determine characteristics of coded
bitstreams and to test compliance of bitstreams and decoders with the requirements specified in Parts 1, 2
and 3.
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:
whether the encoder
manufacturers of encoders , and customers, can use the tests to verify
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.

INTERNATIONAL STANDARD@ ‘SO/‘EC lSO/IEC 11172-4: 1995 (E)
Information technology - Coding of moving pictures
and associated audio for digital storage media at up to
about I,5 Mbit/s -
Part 4:
Compliance testing
Section 1: General
1.1 Scope
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 descibed 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.
1.2 Normative references
The following International Standards contain provisions which, through reference in this text, constitute
provisions of this part of ISO/IEC 11172. At the time of publication, the editions indicated were valid.
All standards are subject to revision, and parties to agreements based on this part of ISO/IEC 11172 are
encouraged to investigate the possibility of applying the most recent editions of the standards indicated
below. Members of IEC and IS0 maintain registers of currently valid International Standards.
ISO/IEC 11172- 1: 1993 Information technology - Coding of moving pictures and associated audio for digital
storage media at up to about 1,5 MbitLs - Part I: Systems.
ISO/IEC 11172-2: 1993 Information technology - Coding of moving pictures and associated audio for digital
storage media at up to about I,5 Mbit/,, - Part 2: Video.
ISO/IEC 11172-3: 1993 Information technology - Coding of moving pictures and associated audio for digital
storage media at up to about 1,5 MbitLs - Part 3: Audio.
0 ISOAEC
ISOAEC I1 172-4: 1995 (E)
CCIR Recommendation 601-2 Encoding parameters of digital television for studios.
CCIR Report 624-4 Characteristics of systems for monochrome and colour television.
CCIR Recommendation 648 Recording of audio signals.
CCIR Report 955-2 Sound broadcasting by satellite for portable and mobile receivers, including Annex IV
of Advanced Digital System II.
Summary description
CCITT Recommendation J. 17 Pre-emphasis used on Sound-Programme Circuits.
IEEE Draft Standard P118O/D2 1990 Specification for the implementation of 8x8 inverse discrete cosine
transform ‘:
IEC publication 908: 1987 CD Digital Audio System.
Section 2: Technical elements
2.1 Definitions
For the purposes of this part of ISO/IEC 11172, the following definitions apply. If the definition is
specific to a part, this is noted in square brackets.
2.1.1 ac coefficient [video]: Any DCT coefficient for which the frequency in one or both dimensions
is non-zero.
In the case of compressed audio an access unit is an audio access unit. In
2.1 .2 access unit [system]:
an access unit is the coded representation of a picture.
the case of compressed video
2. 1.3 adaptive segmentation [audio]: A subdivision of the digital representation of an audio signal
variable segments of time.
2.1.4 adaptive bit allocation [audio]: The assignment of bits to subbands in a time and frequency
varying fashion according to a psychoacoustic model.
noise to frequency bands in a
2.1.5 adaptive noise allocation [audio]: The assignment of coding
time and frequency varying fashion according to a psychoacoustic model.
2.1.6 alias [audio]: Mirrored signal component resulting from sub-Nyquist sampling.
2.1.7 analysis filterbank [audio]: Filterbank in the encoder that transforms a broadband PCM audio
signal into a set of subsampled subband samples.
2.1.8 audio access unit [audio]: For Layers I and II an audio access unit is defined as the smallest
part of the encoded bitstream which can be decoded by itself, where decoded means “fully reconstructed
sound”. For Layer III an audio access unit is part of the bitstream that is decodable with the use of
previously acquired main information.
2.1.9 audio buffer [audio]: A buffer in the system target decoder for storage of compressed audio data.
2.1.10 audio sequence [audio]: A non-interrupted series of audio frames in which the following
parameters are not changed:
- ID
- Layer
- Sampling Frequency
- For Layer I and II: Bitrate index
2.1.11 backward motion vector [video]: A motion vector that is used for motion compensation
from a reference picture at a later time in display order.
ISOAEC 11172-4: 1995 (E)
0 ISOAEC
2.1.12 Bark [audio]: Unit of critical band rate. The Bark scale is a non-linear mapping of the frequency
scale over the audio range closely corresponding with the frequency selectivity of the human ear across the
band.
2.1.13 bidirectionally predictive-coded picture;
B-picture [video]: A picture that is coded
using motion compensated prediction from a past and/or future reference picture.
2.1.14 bitrate: The rate at which the compressed bitstream is delivered from the storage medium to the
input of a decoder.
2.1.15 bitstream characteristics [compliance]: The subset of the standard that is exploited by the
encoder in generating the bitstream. For example, an encoder may apply syntactic and semantic constraints,
such as restricted ranges of parameters, to produce a bitstream that exploits a subset of the capabilities
supported by parts 1,2 and 3 of ISO/IEC 11172. Examples are the applied values or range of the picture
size and bitrate parameters in video bitstreams.
2.1.16 bitstream compliance [compliance]: A bitstream is compliant, if the bitstream meets the
syntactic and semantic bitstream requirements, specified in the normative clauses of parts 1,2 and 3 of
ISOPIEC 11172.
2.1.17 bitstream requirements [compliance]: Requirements for bitstreams defined in the normative
clauses of parts 1, 2 and 3 of ISO/IEC 11172.
2.1.18 block companding [audio]: Normalizing of the digital representation of an audio signal
within a certain time period.
2.1.19 block [video]: An 8-row by &column orthogonal block of pels.
2.1.20 bound [audio]: The lowest subband in which intensity stereo coding is used.
2.1.21 byte aligned: A bit in a coded bitstream is byte-aligned if its position is a multiple of &bits
from the first bit in the stream.
2.1.22 byte: Sequence of &bits.
2.1.23 channel: A digital medium that stores or transports an ISO/IEC 11172 stream.
2.1.24 channel [audio]: The left and right channels of a stereo signal
2.1.25 chrominance (component) [video]: A matrix, block or single pel representing one of the
two colour difference signals related to the primary colours in the manner defined in CCIR Ret 601. The
symbols used for the colour difference signals are Cr and Cb.
2.1.26 coded audio bitstream [audio]: A coded representation of an audio signal as specified in
ISO/IEC 11172-3.
2.1.27 coded video bitstream [video]: A coded representation of a series of one or more pictures as
specified in ISO/IEC 11172-2.
2.1.28 coded order [video]: The order in which the pictures are stored and decoded. This order is not
necessarily the same as the display order.
2.1.29 coded representation: A data e
...