ETSI TS 102 563 V2.1.1 (2017-01)

ETSI TS 102 563 V2.1.1 (2017-01)
TECHNICAL SPECIFICATION
Digital Audio Broadcasting (DAB);
DAB+ audio coding (MPEG HE-AACv2)
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2 ETSI TS 102 563 V2.1.1 (2017-01)
Reference
RTS/JTC-DAB-82
Keywords
audio, broadcasting, coding, DAB, digital
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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 Definitions, abbreviations and arithmetic operators ................................................................................. 6

3.1 Definitions .......................................................................................................................................................... 6

3.2 Abbreviations ..................................................................................................................................................... 7

3.3 Arithmetic operators ........................................................................................................................................... 7

4 Introduction .............................................................................................................................................. 7

5 Audio ........................................................................................................................................................ 8

5.1 HE-AACv2 audio coding ................................................................................................................................... 8

5.2 Audio super framing syntax ............................................................................................................................... 9

5.3 MPEG Surround ............................................................................................................................................... 12

5.3.1 Overview .................................................................................................................................................... 12

5.3.2 Requirements for MPEG Surround encoders and decoders ........................................................................ 13

5.3.3 Operational aspects of broadcasting ........................................................................................................... 13

5.3.4 Receiver implementation aspects ................................................................................................................ 13

5.4 Programme Associated Data (PAD) ................................................................................................................. 14

5.4.0 Introduction................................................................................................................................................. 14

5.4.1 PAD insertion ............................................................................................................................................. 14

5.4.2 Coding of F-PAD and X-PAD .................................................................................................................... 15

5.4.3 PAD extraction ........................................................................................................................................... 15

6 Transport error coding and interleaving ................................................................................................. 16

6.0 Introduction ...................................................................................................................................................... 16

6.1 RS coding ......................................................................................................................................................... 16

6.2 Formation of the coding array .......................................................................................................................... 17

6.3 Formation of the parity array ............................................................................................................................ 17

6.4 Formation of the output array ........................................................................................................................... 17

6.5 Order of data transmission................................................................................................................................ 17

7 Signalling ............................................................................................................................................... 17

7.1 FIC signalling ................................................................................................................................................... 17

7.2 Audio parameter signalling .............................................................................................................................. 17

8 Reconfiguration ...................................................................................................................................... 18

Annex A (normative): Error concealment ......................................................................................... 19

A.0 Introduction ............................................................................................................................................ 19

A.1 AAC error concealment.......................................................................................................................... 19

A.1.0 Introduction ...................................................................................................................................................... 19

A.1.1 Interpolation of one corrupt AU ....................................................................................................................... 19

A.1.2 Fade-out and fade-in ......................................................................................................................................... 20

A.2 SBR error concealment .......................................................................................................................... 20

A.3 Parametric stereo error concealment ...................................................................................................... 22

A.4 MPEG Surround error concealment ....................................................................................................... 22

Annex B (informative): Implementation tips for PAD insertion........................................................ 23

Annex C (informative): Synchronizing to the audio super frame structure ..................................... 24

Annex D (informative): Processing a super frame .............................................................................. 26

Annex E (informative): Bit-rate available for audio ........................................................................... 27

History .............................................................................................................................................................. 28

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pertaining to these essential IPRs, if any, is publicly available for ETSI members and non-members, and can be found

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can be given as to the existence of other IPRs not referenced in ETSI SR 000 314 (or the updates on the ETSI Web

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

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

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 World DAB, an organization with members drawn from broadcasting

organizations and telecommunication providers together with companies from the professional and consumer

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

"must" and "must not" are NOT allowed in ETSI deliverables except when used in direct citation.

The present document defines the method to code and transmit audio services using the HE-AACv2 [2] audio coder for

Eureka-147 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.

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 documents which are not found to be publicly available in the expected location might be found at

NOTE: While any hyperlinks included in this clause were valid at the time of publication, ETSI cannot guarantee

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

[2] ISO/IEC 14496-3: "Information technology - Coding of audio-visual objects - Part 3: Audio".

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

NOTE: While any hyperlinks included in this clause were valid at the time of publication, ETSI cannot guarantee

The following referenced documents are not necessary for the application of the present document but they assist the

[i.1] ISO/IEC 23003-1: "Information technology - MPEG audio technologies - Part 1: MPEG

For the purposes of the present document, the terms and definitions given in ETSI EN 300 401 [1] and the following

access unit: access unit contains the audio samples for 20 ms, 30 ms, 40 ms or 60 ms of audio depending on the

audio super frame: audio super frame contains a number of AUs which together contain the encoded audio for 120 ms

subchannel_index: subchannel_index is derived from the size of the sub-channel carrying the audio service and defines

For the purposes of the present document, the abbreviations given in ETSI EN 300 401 [1] and the following apply:

m DIV p denotes the quotient part of the division of m by p (m and p are positive integers)

m MOD p denotes the remainder of the division of m by p (m and p are positive integers)

The DAB system standard [1] allows audio (programme) services to be carried using either DAB audio or DAB+ audio.

The present document defines the way that audio (programme) services are carried when using DAB+ audio (MPEG 4

MPEG 4 HE-AACv2 specifies two transforms, but only the 960 transform is permitted for DAB+ audio, with core

sampling rates of 48 kHz, 32 kHz, 24 kHz and 16 kHz. Each AU (audio frame) contains samples for 20 ms, 30 ms,

40 ms or 60 ms respectively. AUs are built into audio super frames of 120 ms duration which are then carried in five

DAB logical frames. In order to provide additional error control, Reed Solomon coding and virtual interleaving is

For generic audio coding, a subset of the MPEG-4 High Efficiency Advanced Audio Coding v2 (HE-AACv2) profile

chosen to best suit the DAB system environment is used. The HE-AACv2 Profile, Level 2 according to [2] shall apply

• Sampling rates: permitted output sampling rates of the HE-AACv2 decoder are 32 kHz and 48 kHz, i.e. when

SBR is enabled the AAC core shall be operated at 16 kHz or 24 kHz, respectively. If SBR is disabled then the

• Transform length: the number of samples per channel per AU is 960. This is required to harmonize HE-AAC

AU lengths to allow the combination of an integer number of AUs to build an audio super frame of 120 ms

• Audio bit rates are restricted to fit within a maximum sub-channel size of 192 kbps (approximately 175 kbps

• Audio super framing: AUs are composed into audio super frames, which always correspond to 120 ms in time.

The AUs in the audio super frames are encoded together such that each audio super frame is of constant

length, i.e. that bit exchange between AUs is only possible within an audio super frame. The number of AUs

per super frame are: two (16 kHz AAC core sampling rate with SBR enabled), three (24 kHz AAC core

sampling rate with SBR enabled), four (32 kHz AAC core sampling rate) or six (48 kHz AAC core sampling

Each audio super frame is carried in five consecutive logical DAB frames (see clause 7) which enables simple

synchronization and management of reconfigurations. The size of the audio super frame is defined by the size of the

MSC sub-channel (see ETSI EN 300 401 [1], clause 6.2.1) which carries the audio super frame. Sub-channels are

multiples of 8 kbps in size. The size of the audio super frame in bytes is given by the expressions below:

The first byte of the audio super frame is byte 0 and the last byte is byte (audio_super_frame_size - 1).

NOTE: The subchannel_index parameter may take the values 1 to 24 due to the restriction limiting the maximum

The header contains the audio parameters for the audio super frame and the respective start positions of each AU within

the audio super frame, along with an error protection word. The au_start values for the second and subsequent AUs are

stored consecutively in the header. Depending on the number of AUs, 4 padding bits are added to achieve byte-

The number of AUs in the audio super frame is determined by the settings of the audio parameters. num_aus may take

The AU contains the audio samples for 20 ms, 30 ms, 40 ms or 60 ms of audio depending on the core sampling rate,

The CRC shall be generated according to the procedure defined in ETSI EN 300 401 [1], annex E. The generation shall

The CRC word shall be complemented (1s complement) prior to transmission. At the beginning of each CRC word

if ((dac_rate == 0) && (sbr_flag == 1)) num_aus = 2; AAC core sampling rate 16 kHz

if ((dac_rate == 1) && (sbr_flag == 1)) num_aus = 3; AAC core sampling rate 24 kHz

if ((dac_rate == 0) && (sbr_flag == 0)) num_aus = 4; AAC core sampling rate 32 kHz

if ((dac_rate == 1) && (sbr_flag == 0)) num_aus = 6; AAC core sampling rate 48 kHz

NOTE: The au_start for the first AU in the audio super frame (au_start[0]) is not transmitted. The first AU always

The header_firecode is a 16-bit field containing a Fire code capable of detecting and correcting most single error burst

of up to 6 bits. The error pattern 101111 (where "1" indicates "bit error", "0" indicates "no bit error") can be detected

The Fire code word shall be calculated over the nine bytes from byte 2 to byte 10 of the audio super frame.

NOTE 1: Except in the case where num_aus = 6, the Fire code calculation will include some bytes from the first

At the beginning of each Fire code word calculation, all register stages shall be initialized to "0".

The audio parameters comprise the rfa, dac_rate, sbr_flag, aac_channel_mode, ps_flag and mpeg_surround_config

NOTE 3: When the audio parameters are changed, some interruption to the audio output should be expected.

The rfa is a 1-bit field reserved for future addition. This bit shall be set to zero for the currently specified application.

The dac_rate is a 1-bit field to signal the sampling rate of the DAC according to table 3.

The number of output channels provided by MPEG Surround is intended as an information for the listener only. The

MPEG Surround decoder shall use this information only to determine whether MPEG Surround is used. If MPEG

Surround is used (mpeg_surround_config ≠ 000), the MPEG Surround decoder shall exclusively rely on the information

The au_start is an unsigned integer, most significant bit first, carried in a 12-bit field that defines the start position

within the audio super frame of the respective AU by giving the byte number of the first byte of the AU. The value of

The decoder can derive the value of au_size[n] from the received au_start[n] and au_start[n + 1].

MPEG Surround is standardized in MPEG-D, Part-1 (ISO/IEC 23003-1 [i.1]). It describes:

• Coding of multichannel signals based on a downmixed signal of the original multichannel signal, and

associated spatial parameters. It offers lowest possible data rate for coding of multichannel signals, as well as

an inherent mono or stereo downmix signal included in the data stream. Hence, a mono or stereo signal can be

• Binaural decoding of the MPEG Surround stream, enabling a surround sound experience over headphones.

• An Enhanced Matrix Mode that enables a multi-channel upmix from a stereo signal without any spatial

Hence, MPEG Surround (Spatial Audio Coding, SAC) is capable of re-creating N channels based on M < N transmitted

channels, and additional control data. In the preferred modes of operating the spatial audio coding system, the

M channels can either be a single mono channel or a stereo channel pair. The control data represents a significantly

lower data rate than required for transmitting all N channels, making the coding very efficient while at the same time

The MPEG Surround standard incorporates a number of tools that provide features which enable broad application of

the standard. A key feature is the ability to scale the spatial image quality gradually from very low spatial overhead

towards transparency. Another key feature is that the decoder input can be made compatible to existing matrix surround