ETSI ETS 300 149 ed.1 (1992-03)

SLOVENSKI STANDARD
SIST ETS 300 149 E1:2003
01-december-2003
Terminalska oprema (TE) – Videotex – Zvokovna skladnja
Terminal Equipment (TE); Videotex Audio syntax
Ta slovenski standard je istoveten z: ETS 300 149 Edition 1
ICS:
33.160.99 Druga avdio, video in Other audio, video and
avdiovizuelna oprema audiovisual equipment
35.180 Terminalska in druga IT Terminal and other
periferna oprema IT peripheral equipment
SIST ETS 300 149 E1:2003 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST ETS 300 149 E1:2003

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SIST ETS 300 149 E1:2003
EUROPEAN ETS 300 149
TELECOMMUNICATION March 1992
STANDARD
Source: ETSI TC-TE Reference: DE/TE-01007
ICS:
Videotex, Audio syntax
Key words:
Terminal Equipment (TE);
Videotex
Audio syntax
ETSI
European Telecommunications Standards Institute
ETSI Secretariat
F-06921 Sophia Antipolis CEDEX - FRANCE
Postal address:
650 Route des Lucioles - Sophia Antipolis - Valbonne - FRANCE
Office address:
c=fr, a=atlas, p=etsi, s=secretariat - secretariat@etsi.fr
X.400: Internet:
Tel.: +33 92 94 42 00 - Fax: +33 93 65 47 16
Copyright Notification: No part may be reproduced except as authorized by written permission. The copyright and the
foregoing restriction extend to reproduction in all media.
© European Telecommunications Standards Institute 1992. All rights reserved.
New presentation - see History box

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ETS 300 149: March 1992
Whilst every care has been taken in the preparation and publication of this document, errors in content,
typographical or otherwise, may occur. If you have comments concerning its accuracy, please write to
"ETSI Editing and Committee Support Dept." at the address shown on the title page.

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Contents
Foreword .5
1 Scope .7
2 Normative references .7
3 Definitions, symbols and abbreviations .8
3.1 Definitions.8
3.2 Symbols and abbreviations .8
4 Overview . 9
5 Introducer. 9
6 ISO/IEC 9281 syntax and switching structure .9
6.1 Overall switching of coding environment.9
6.2 Switching into the audio mode. 10
6.3 ISO/IEC 9281 syntax structure. 11
7 Sound header . 13
7.1 Introduction . 13
7.2 Header structure . 13
7.2.1 Concepts . 13
7.2.2 Encoding . 13
7.2.3 Bitrate . 14
7.2.4 Recording level . 14
7.2.5 Translation mode . 14
7.2.6 Synchronisation mode . 14
7.3 Default values . 15
8 Sound block . 15
9 Application rules for ISDN syntax-based Videotex . 16
9.1 Encoding/bitrate combinations. 16
9.2 Translation mechanisms . 16
Annex A (normative): Translation modes. 17
A.1 Mode 0. 17
A.2 Mode 1 (no translation except US). 17
A.3 Mode 2 (3-in-4 coding) . 17
A.4 Mode 3 (shift scheme - 8-bits). 18
A.5 Mode 4 (shift scheme - 7-bits). 18
History. 20

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ETS 300 149: March 1992
Foreword
This European Telecommunication Standard (ETS) has been prepared by the Terminal Equipment (TE)
Technical Committee of the European Telecommunications Standards Institute (ETSI).
This ETS is part of a series of standards which describe the Videotex data syntax and is consistent with
the work being carried out by CCITT Study Group VIII on Question 14. It also specifies a common data
syntax for transmitting sound to be used by Videotex terminal equipment.
This ETS defines a data syntax for conveying audio data in a Videotex environment. In this data syntax a
variety of audio encoding techniques are embedded in one general structure. No algorithms or specific
sound encodings are specified. It allows for the embedding of both waveform and phonemic encodings.
This ETS closely follows the concepts and coding techniques as defined in ISO/IEC 9281 [1] for the
identification of pictorial information and for switching between picture encoding environments and coding
systems according to ISO 2022 [2].

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1 Scope
This standard specifies the data syntax to be used by Videotex services for conveying sound information.
This standard is applicable to terminals connected to public data networks. Typically, these should be
terminals, supporting Integrated Services Digital Network (ISDN) syntax-based Videotex, to be attached at
either side of a T reference point or coincident S and T reference points of a public ISDN.
2 Normative references
This ETS incorporates by dated or undated reference, provisions from other publications. These normative
references are cited at the appropriate places in the text and the publications are listed hereafter. For
dated references, subsequent amendments to, or revisions of any of these publications apply to this ETS
only when incorporated in it by amendment or revision. For undated references the latest edition of the
publication referred to applies.
[1] ISO 9281: "Information technology - Picture coding methods".
[2] ISO 2022: "Information Processing - ISO 7-bit and 8-bit coded character sets -
Code extension techniques".
[3] ETS 300 072 (1990): "Terminal Equipment (TE);
Videotex presentation layer protocol, Videotex presentation layer data syntax".
[4] ETS 300 073 (1990): "Videotex presentation layer data syntax : Geometric
display (CEPT Recommendation T/TE 06-03, Edinburgh 1988)".
[5] ETS 300 074 (1990): "Videotex presentation layer data syntax : Transparent
data (CEPT Recommendation T/TE 06-03, Edinburgh 1988)".
[6] ETS 300 075 "1990": "Terminal Equipment (TE); Videotex processable data".
[7] ETS 300 076 (1990): "Terminal Equipment (TE); Videotex, Terminal Facility
Identifier (TFI)".
[8] CCITT Recommendation T.101 (1988): "International Interworking for Videotex".
[9] ISO 646: "Information processing - ISO 7-bit coded character set for information
exchange".
[10] CCITT Recommendation G.711 (1988): "Pulse code modulation of voice
frequencies".
[11] CCITT Recommendation G.721 (1988): "32 kbit/s adaptive differential pulse
code modulation.
[12] CCITT Recommendation G.723 (1988): "Extensions of Recommendation G.721
ADPCM to 24 and 40 kbit/s for DCME application".
[13] CCITT Recommendation G.722 (1988): "7 kHz audio-coding within 64 kbit/s".
[14] GSM Specification 06.10: "GSM Full-rate speech transcoding".
[15] CCITT Recommendation J.41: "Characteristics of equipment for the coding of
analogue high quality sound programme signals for transmission on 384 kbit/s
channels".
[16] CCITT Recommendation J.42: "Characteristics of equipment for the coding of
analogue medium quality sound programme signals for transmission on 384
kbit/s channels".

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3 Definitions, symbols and abbreviations
3.1 Definitions
For the purposes of this ETS, the following definitions apply:
Audio bit rate: the bit rate required to convey data which is coded according to a specific encoding in real
time.
Data Syntax: data syntax I, II or III.
Data Syntax I: data syntax used in the CAPTAIN system.
Data Syntax II: European data syntax (ETSs 300 072 to 300 076 [3] to [7]).
Data Syntax III: data syntax used in the NAPLPS system.
NOTE : The three data syntaxes above are described in CCITT Recommendation T.101 [8].
Encoding: coding method of audio data according to a specific algorithm and coding convention.
Recording level: the mean level of the sound signal as it was recorded.
Sampling rate: aspect of a sound encoding defining the amount of samples encoded per time unit.
Synchronisation mode: attribute of an encoding defining the synchronisation to be applied to the audio
data.
Transfer rate: the effective amount of data bits which can be exchanged between communicating entities.
Translation mode: attribute of an encoding defining the method of packing data into octets in order to
achieve transparency.
3.2 Symbols and abbreviations
For the purposes of this ETS the following abbreviations apply:
ADPCM Adaptive Differential Pulse Code Modulation
AM Alphamosaic
CMI Coding Method Identifier
GSM Special Mobile Group
LI Length Indicator
MI Method Identifier
P Profile in Data syntax II
PCD Picture Coding Delimiter
PCE Picture Control Entity
PCM Pulse Code Modulation
PDE Picture Data Entity
PE Picture Entity
PI Picture Identifier

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PM Picture Mode
RPE-LTP Residual Pulse Excitation - Long Term Predictive
VPCE Videotex Presentation Control Element
4 Overview
The audio data syntax allows for the embedding of a variety of different audio-coding techniques in one
single overall structure. Each information element is tagged with an introducer indicating:
- the coding technique being used;
- the audio bit rate of the coding.
The audio bit rate indicates the bit rate with which the used encoding can be conveyed in real time. The
audio bit rate is strongly related to the sampling rate and may be different from the actual transfer rate of
the protocol being used for data exchange.
The audio data syntax provides for block-wise transmission of audio data, thus avoiding the need for
terminals to scan through streams of audio data for delimiter sequences.
To increase the actual data throughput, the audio data syntax provides for transparent data transport,
thereby surpassing the coding convention, that data representing information is coded in columns 2 - 7
(and 10 - 15 in a 8-bit environment).
5 Introducer
The introducer for sound shall be in accordance with ISO/IEC 9281 [1] and has the following coding: ESC
7/0 2/4 where 2/4 identifies audio-coding.
The return from the sound environment may be done by using ESC 2/5 4/0 (return to default ISO 2022 [2]
environment) or by switching explicitly to an identified environment using another ESC 2/5 x/y sequence, or
by the end of an ISO/IEC 9281 [1] picture element, at which time the current ISO 2022 [2] coding
environment (i.e. the base Videotex data syntax) takes effect.
6 ISO/IEC 9281 syntax and switching structure
In some Videotex systems, in a situation where an interruption of the audio data flow is required (caused
probably by user interaction) the following may occur. The Picture Entity (PE) being sent to the terminal is
completely sent. The next PE sent to the terminal can have the Picture Data Entity (PDE) value set to
04/02 to indicate the end of the data, the PDE will contain only byte (Length Indicator = 1).
If possible, the speed of the network should be taken into account when defining the number of bytes in a
PDE with the aim of tolerable interaction response time. As a rough guide, a block length that does not
result in a response time exceeding 200 ms - 500 ms may by used.
6.1 Overall switching of coding environment
ISO/IEC 9281 [1] describes a technique for identifying coding methods. The Videotex photographic audio
mode is one of the coding methods identified by ISO/IEC 9281 [1]. The diagram in figure 1 gives an
overview of the relationship between the Videotex data syntaxes and ISO/IEC 9281 [1] coding
environments.
A Videotex data syntax can be explicitly entered using an ESC 2/5 F code, this is also the mechanism for
entering an ISO/IEC 9281 [1] environment. The Videotex data syntaxes can therefore be regarded as
being ISO/IEC 9281 [1] environments.

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ETS 300 149: March 1992
A Videotex terminal should usually begin operation, by default, in one of the data syntaxes. It shall not be
mandatory to first send an ESC 2/5 F code. The diagram shows how these codes can be used to switch a
terminal supporting more than one data syntax from one data syntax to another.
NOTE: It is advisable that the Videotex service explicitly switches the terminal into the required
data syntax by sending an ESC 2/5 F sequence to the terminals at connect time.
6.2 Switching into the audio mode
A Videotex terminal operating within one of the data syntaxes can enter the audio mode with the code ESC
7/0 Coding Method Identifier (CMI), as defined in ISO/IEC 9281 [1]. The CMI is used to distinguish
between coding methods. In the case of Videotex this shall be, for example, a distinction between audio
and photographic data.
An alternative mechanism is defined by ISO/IEC 9281 [1] for entering a coding environment. A unique ESC
2/5 F code is registered for the purpose of switching directly into this coding environment. This implies that
a non-Videotex terminal can enter the Videotex audio mode. A Videotex terminal can also use an ESC 2/5
F code to enter a particular environment, in this situation the terminal operation is not defined by a data
syntax and no assumptions can be made about the terminal model (see ETS 300 076 [7]).

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ETS 300 149: March 1992
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