ETSI TS 103 466 V1.2.1 (2019-09)

Digital Audio Broadcasting (DAB); DAB audio coding (MPEG Layer II)

RTS/JTC-DAB-96

General Information

• Status: Published
• Publication Date: 29-Sep-2019
• Technical Committee: BROADCAS - EBU/CENELEC/ETSI on Broadcasting
• Current Stage: 12 - Completion
• Due Date: 30-Sep-2019
• Completion Date: 30-Sep-2019

Standards Content (Sample)

ETSI TS 103 466 V1.2.1 (2019-09)






TECHNICAL SPECIFICATION
Digital Audio Broadcasting (DAB);
DAB audio coding (MPEG Layer II)

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2 ETSI TS 103 466 V1.2.1 (2019-09)



Reference
RTS/JTC-DAB-96
Keywords
audio, broadcasting, coding, DAB, digital
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3 ETSI TS 103 466 V1.2.1 (2019-09)
Contents
Intellectual Property Rights . 5
Foreword . 5
Modal verbs terminology . 5
1 Scope . 6
2 References . 6
2.1 Normative references . 6
2.2 Informative references . 6
3 Definition of terms, abbreviations, mathematical symbols and convention . 7
3.1 Terms . 7
3.2 Abbreviations . 9
3.3 Mathematical symbols . 10
3.3.1 Arithmetic operators . 10
3.3.2 Logical and set operators . 10
3.3.3 Functions . 10
3.3.4 Constants . 10
3.4 C-language mathematical symbols . 11
3.4.1 Arithmetic operators . 11
3.4.2 Logical operators . 11
3.4.3 Relational operators . 11
3.4.4 Assignment . 11
3.4.5 Mnemonics . 11
3.4.6 Method of describing bit stream syntax . 12
3.5 Convention . 13
4 Introduction . 13
5 DAB audio coding . 13
5.1 Introduction . 13
5.2 Audio encoding . 14
5.2.0 General . 14
5.2.1 Analysis sub-band filter . 15
5.2.2 Scale Factor calculation . 17
5.2.3 Coding of Scale Factors . 17
5.2.4 Coding of Scale Factor Selection Information . 18
5.2.5 Psychoacoustic model . 19
5.2.6 Bit allocation . 19
5.2.7 Bit allocation coding . 20
5.2.8 Quantization and coding of sub-band samples. 22
5.2.9 Formatting of the audio bit stream . 24
5.3 Semantics of the audio bit stream . 25
5.3.1 MPEG Audio Layer II bit stream . 25
5.3.1.1 Audio sequence . 25
5.3.1.2 Audio frame . 25
5.3.1.3 Audio frame header . 25
5.3.1.4 Error check . 28
5.3.1.5 Audio data . 28
5.3.1.6 Ancillary data . 29
5.3.2 DAB audio bit stream . 29
5.3.2.0 Introduction . 29
5.3.2.1 DAB audio sequence . 29
5.3.2.2 DAB audio frame . 29
5.3.2.3 DAB audio frame header . 30
5.3.2.4 Error check . 30
5.3.2.5 Audio data . 30
5.3.2.6 Audio stuffing bits . 30
5.3.2.7 Extended Programme Associated Data (X-PAD) . 30
ETSI

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4 ETSI TS 103 466 V1.2.1 (2019-09)
5.3.2.8 Scale Factor Error Check (ScF-CRC) . 31
5.3.2.9 Fixed Programme Associated Data (F-PAD) . 31
5.4 Audio bit stream syntax . 33
5.4.0 Introduction. 33
5.4.1 ISO/IEC 11172-3 and ISO/IEC 13818-3 Layer II bit stream syntax . 33
5.4.1.0 General . 33
5.4.1.1 Audio sequence . 33
5.4.1.2 Audio frame . 33
7.3.1.3 Header . 33
5.4.1.4 Error check . 34
5.4.1.5 Audio data . 34
5.4.1.6 Ancillary data . 35
5.4.2 DAB audio bit stream syntax . 35
5.4.2.0 General . 35
5.4.2.1 DAB audio sequence . 35
5.4.2.2 DAB audio frame . 35
5.4.2.3 DAB audio frame header . 35
5.4.2.4 Error check . 35
5.4.2.5 Audio data . 35
5.4.2.6 Audio stuffing bits . 36
5.4.2.7 Extended Programme Associated Data . 36
5.4.2.8 Scale factor error check . 36
5.4.2.9 Fixed Programme Associated Data . 36
5.5 Programme Associated Data (PAD) . 37
5.5.1 Coding . 37
5.5.2 Transport . 37
5.5.3 Dynamic Range Control data . 38
Annex A (informative): Main characteristics of the audio coding system . 39
A.1 Audio signal characteristics . 39
A.2 Audio coding characteristics . 39
A.3 Audio associated data characteristics . 40
Annex B (normative): Audio decoding . 41
B.1 General . 41
B.2 CRC check for audio side information . 41
B.3 CRC check for Scale Factors . 41
B.4 Decoding of the MPEG Audio Layer II bit stream . 42
Annex C (informative): Audio encoding . 43
C.1 Analysis sub-band filter. 43
C.2 Psychoacoustic model . 46
C.3 Bit allocation procedure . 54
C.4 Bit sensitivity to errors . 56
C.5 Error concealment . 57
C.6 Joint stereo coding . 57
History . 60

ETSI

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5 ETSI TS 103 466 V1.2.1 (2019-09)
Intellectual Property Rights
Essential patents
IPRs essential or potentially essential to normative deliverables may have been declared to ETSI. The information
pertaining to these essential IPRs, if any, is publicly available for ETSI members and non-members, and can be found
in ETSI SR 000 314: "Intellectual Property Rights (IPRs); Essential, or potentially Essential, IPRs notified to ETSI in
respect of ETSI standards", which is available from the ETSI Secretariat. Latest updates are available on the ETSI Web
server (https://ipr.etsi.org/).
Pursuant to the ETSI IPR Policy, no investigation, including IPR searches, has been carried out by ETSI. No guarantee
can be given as to the existence of other IPRs not referenced in ETSI SR 000 314 (or the updates on the ETSI Web
server) which are, or may be, or may become, essential to the present document.
Trademarks
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not constitute an endorsement by ETSI of products, services or organizations associated with those trademarks.
Foreword
This Technical Specification (TS) has been produced by Joint Technical Committee (JTC) Broadcast of the European
Broadcasting Union (EBU), Comité Européen de Normalisation ELECtrotechnique (CENELEC) and the European
Telecommunications Standards Institute (ETSI).
NOTE 1: The EBU/ETSI JTC Broadcast was established in 1990 to co-ordinate the drafting of standards in the
specific field of broadcasting and related fields. Since 1995 the JTC Broadcast became a tripartite body
by including in the Memorandum of Understanding also CENELEC, which is responsible for the
standardization of radio and television receivers. The EBU is a professional association of broadcasting
organizations whose work includes the co-ordination of its members' activities in the technical, legal,
programme-making and programme-exchange domains. The EBU has active members in about
60 countries in the European broadcasting area; its headquarters is in Geneva.
European Broadcasting Union
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Tel: [phone]
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The Eureka Project 147 was established in 1987, with funding from the European Commission, to develop a system for
the broadcasting of audio and data to fixed, portable or mobile receivers. Their work resulted in the publication of
European Standard, ETSI EN 300 401 [1], for DAB (see note 2) which now has worldwide acceptance.
NOTE 2: DAB is a registered trademark owned by one of the Eureka Project 147 partners.
The DAB family of standards is supported by WorldDAB, an organization with members drawn from broadcasting
organizations and telecommunication providers together with companies from the professional and consumer
electronics industry.
Modal verbs terminology
In the present document "shall", "shall not", "should", "should not", "may", "need not", "will", "will not", "can" and
"cannot" are to be interpreted as described in clause 3.2 of the ETSI Drafting Rules (Verbal forms for the expression of
provisions).
"must" and "must not" are NOT allowed in ETSI deliverables except when used in direct citation.
ETSI

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6 ETSI TS 103 466 V1.2.1 (2019-09)
1 Scope
The present document defines the method to code and transmit audio services using the MPEG Layer II audio coder for
Digital Audio Broadcasting (DAB) (ETSI EN 300 401 [1]) and details the necessary mandatory requirements for
decoders. The permitted audio modes and the data protection and encapsulation are detailed. This audio coding scheme
permits the full use of the PAD channel for carrying dynamic labels and user applications.
2 References
2.1 Normative references
References are either specific (identified by date of publication and/or edition number or version number) or
non-specific. For specific references, only the cited version applies. For non-specific references, the latest version of the
referenced document (including any amendments) applies.
Referenced documents which are not found to be publicly available in the expected location might be found at
https://docbox.etsi.org/Reference/.
NOTE: While any hyperlinks included in this clause were valid at the time of publication, ETSI cannot guarantee
their long term validity.
The following referenced documents are necessary for the application of the present document.
[1] ETSI EN 300 401 (V2.1.1): "Radio Broadcasting Systems; Digital Audio Broadcasting (DAB) to
mobile, portable and fixed receivers".
[2] ISO/IEC 11172-3 (1993): "Information technology - Coding of moving pictures and associated
audio for digital storage media at up to 1,5 Mbit/s - Part 3: Audio".
[3] IEC 60958 (all parts): "Digital audio interface".
[4] ISO/IEC 13818-3: "Information technology - Generic coding of moving pictures and associated
audio information - Part 3: Audio".
2.2 Informative references
References are either specific (identified by date of publication and/or edition number or version number) or
non-specific. For specific references, only the cited version applies. For non-specific references, the latest version of the
referenced document (including any amendments) applies.
NOTE: While any hyperlinks included in this clause were valid at the time of publication, ETSI cannot guarantee
their long term validity.
The following referenced documents are not necessary for the application of the present document but they assist the
user with regard to a particular subject area.
Not applicable.
ETSI

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7 ETSI TS 103 466 V1.2.1 (2019-09)
3 Definition of terms, abbreviations, mathematical
symbols and convention
3.1 Terms
For the purposes of the present document, the terms given in ETSI EN 300 401 [1] and the following apply:
alias component: mirrored signal component resulting from sub-Nyquist sampling
audio bit stream: sequence of consecutive audio frames
audio frame: frame of a duration of 24 ms (at 48 kHz sampling frequency) or of 48 ms (at 24 kHz sampling frequency)
which contains a Layer II encoded audio signal ISO/IEC 11172-3 [2], ISO/IEC 13818-3 [4], corresponding to
1 152 consecutive audio samples
NOTE: It is the smallest part of the audio bit stream which is decodable on its own.
audio mode: audio coding system provides single channel, stereo and joint stereo audio modes
NOTE: In each mode, the complete audio signal is encoded as one audio bit stream.
bark: unit of the critical band
NOTE: The Bark scale is a non-linear mapping of the frequency scale over the entire audio frequency range.
bit allocation: time-varying assignment of bits to samples in different sub-bands according to a psychoacoustic model
bound: lowest sub-band in which Intensity stereo coding is used, in the case of joint stereo mode
Common Interleaved Frame (CIF): serial digital output from the main service multiplexer which is contained in the
Main Service Channel part of the transmission frame
NOTE: It is common to all transmission modes and contains 55 296 bits (i.e. 864 CUs).
convolutional coding: coding procedure which generates redundancy in the transmitted data stream in order to provide
ruggedness against transmission distortions
critical band: psychoacoustic measure in the frequency domain which corresponds to the frequency selectivity of the
human ear
DAB audio frame: Same as audio frame, but includes all specific DAB audio-related information.
dual channel mode: audio mode, in which two audio channels with independent programme contents are encoded
within one audio bit stream
NOTE: This audio mode is not used in DAB.
Equal Error Protection (EEP): error protection procedure which ensures a constant protection of the bit stream
Extended Programme Associated Data (X-PAD): extended part of the PAD carried towards the end of the DAB
audio frame, immediately before the Scale Factor Cyclic Redundancy Check (CRC)
NOTE: Its length is variable.
Fixed Programme Associated Data (F-PAD): fixed part of the PAD contained in the last two bytes of the DAB audio
frame
intensity stereo coding: method of exploiting stereo irrelevance or redundancy in stereophonic audio programmes
NOTE: It is based on retaining only the energy envelope of the right and left channels at high frequencies. At low
frequencies, the fine structure of the left and right channel of a stereophonic signal is retained.
ETSI

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8 ETSI TS 103 466 V1.2.1 (2019-09)
joint stereo mode: audio mode, in which two channels forming a stereo pair (left and right) are encoded within one bit
stream and for which stereophonic irrelevance or redundancy is exploited for further bit reduction
NOTE: The method used in the DAB system is Intensity stereo coding.
logical frame: data burst, contributing to the contents of a sub-channel, during a time interval of 24 ms
EXAMPLE: Data bursts at the output of an audio encoder, a Conditional Access scrambler and a convolutional
encoder are referred to as logical frames. The number of bits contained in a specific logical frame
depends on the stage in the encoding process and the bit rate associated with the sub-channel.
Main Service Channel (MSC): channel which occupies the major part of the transmission frame and which carries all
the digital audio service components, together with possible supporting and additional data service components
masking: property of the human auditory system by which an audio signal cannot be perceived in the presence of
another audio signal
masking threshold: function of frequency and time, specifying the sound pressure level below which an audio signal
cannot be perceived by the human auditory system
N: length of Fast Fourier Transform (FFT)
polyphase filter bank: set of equal-bandwidth filters with special phase relationship, allowing for efficient
implementation of a filter bank
Programme Associated Data (PAD): information which is related to the audio data in terms of contents and
synchronization
NOTE: The PAD field is located at the end of the DAB audio frame.
protection level: level specifying the degree of protection, provided by the convolutional coding, against transmission
errors
protection profile: scheme of convolutional coding applied
psychoacoustic model: mathematical model of the masking behaviour of the human auditory system
Scale Factor (ScF): factor by which a set of values is scaled before quantization
NOTE: The numerical code for the Scale Factor is called the Scale Factor Index.
Scale Factor Select Information (ScFSI): 2-bit code which indicates for each sub-band how many Scale Factors are
coded within the audio frame
service: user-selectable output which can be either a programme service or a data service
service component: part of a service which carries either audio (including PAD) or data
NOTE: The service components of a given service are linked together by the Multiplex Configuration
Information. Each service component is carried either in a sub-channel or in the Fast Information Data
Channel.
side information: information in the encoded audio bit stream which is necessary for controlling the audio decoder
NOTE: This information includes Bit Allocation, Scale Factor Select Information and Scale Factors.
single channel mode:
...