1、ETSI TS 101 757 1.1.1 (2000-06) Technical Specification Digital Audio Broadcasting (DAB); Conformance Testing for DAB Audio 2 ETSI TS 1 O1 757 V1.l.l (2000-06) The pre ent d Reference DTS/JTC-DAB-23 Keywords audio, broadcast, broadcasting, conf, DAB, digital, MPEG, testing ETSI 650 Route des Luciole
2、s F-O6921 Sophia Antipolis Cedex - FRANCE Tel.: +33 4 92 94 42 O0 Fax: +33 4 93 65 47 16 Siret No 348 623 562 0001 7 - NAF 742 C Association but non lucratif enregistre la Sous-prfecture de Grasse (06) No 7803/88 Important notice Individual copies of the present document can be downloaded from: http
3、:/w.etsi.aq cument mav be made available in more than one electronic version or in orint. In anv case f existing or perceived difference in coitents between such versions, the reference version is the Poiable Docuhent Format (PDF). In case of dispute, the reference shall be the printing on ETSI prin
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5、us/ If you find errors in the present document, send your comment to: editor et.si.fr Coovriaht Notification No part may be reproduced except as authorized by written permission. The copyright and the foregoing restriction extend to reproduction in all media. O European Telecommunications Standards
6、Institute 2000. All rights reserved. ETSI 3 ETSI TS 1 O1 757 V1.l.l (2000-06) Contents Intellectual Property Rights 4 Foreword 4 Introduction 5 1 2 3 3.1 3.2 4 4.1 4.2 4.3 4.4 4.5 4.5.1 4.5.2 4.5.3 4.5.4 4.5.5 4.5.6 4.5.7 4.5.8 4.5.9 Scope 6 References 6 Symbols 7 Relational operators 7 Arithmetic o
7、perators . 7 Audio conformance testing 7 Decoder testing arrangement 8 Audio decoder tests 7 Audio decoder characteristics . 9 Requirements for audio bitstreams . 10 Descriptions of the audio test bitstreams 10 Test bitstream #2 . 11 Test bitstream #3 . 11 Test bitstream #4 . 11 Test bitstream #5 .
8、12 Test bitstream #6 . 12 Test bitstream #7 . 12 Test bitstream #8 . 12 Test bitstream #9 . 12 Test bitstream #1 . 11 4.5.10 Test bitstream #10 . 12 Annex A (informative): A Test Method for Dynamic Range Control in Digital Audio Broadcasting Receivers . 13 Bibliography . 19 History 20 ETSI 4 ETSI TS
9、 1 O1 757 V1.l.l (2000-06) Intellectual Property Rights IPRs essential or potentially essential to the present document 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 O00
10、3 14: “Intellectual Propero Rights (IPRs); Essential, or potentially Essential, IPRs notifed to ETSI in respect of ETSI standards“, which is available from the ETSI Secretariat. Latest updates are available on the ETSI Web server (htti,:/www.etsi.oxg/ii-). Pursuant to the ETSI IPR Policy, no investi
11、gation, 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 O00 314 (or the updates on the ETSI Web server) which are, or may be, or may become, essential to the present document. Foreword This Technical Specific
12、ation (TS) has been produced by the Joint Technical Committee (JTC) Broadcast of the European Broadcasting Union (EBU), Comit Europen de Normalisation ELECtrotechnique (CENELEC) and the European Telecommunications Standards Institute (ETSI). NOTE 1: The EBUETSI JTC Broadcast was established in 1990
13、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 E
14、BU 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 headquarter
15、s is in Geneva. European Broadcasting Union CH-1218 GRAND SACONNEX (Geneva) Switzerland Tel: +41 22 717 21 11 Fax: +41 22 717 24 81 EUREKA Project 147 EUREKA Project 147 was established in 1987, with funding from the EC, to develop a system for the broadcasting of audio and data to fixed, portable o
16、r mobile receivers. Their work resulted in the publication of a European Standard, ETS 300 401 2, for DAB (note 2) which now has worldwide acceptance. The members of the Eureka 147 Project are drawn from broadcasting organizations and telecommunication providers together with companies from the prof
17、essional and consumer electronics industry. NOTE 2: DAB is a registered trademark owned by one of the EUREKA 147 partners. ETSI 5 ETSI TS 1 O1 757 V1.l.l (2000-06) Introd uction ETS 300 401 2 specifies the coded representations of audio information to be transmitted over the DAB system. This allows
18、for large flexibility, in terms of bitrate efficiency and protection against errors for transmission in an error prone environment. The flexibility is obtained by including parameters in the bitstream that define the characteristics of coded bitstreams. Examples are the audio sampling frequency and
19、bitrate parameters. The present document specifies a test procedure and defines test bitstreams, which can be used to verify whether bitstreams and decoders meet the requirements as specified in ETS 300 401 2. These tests can be used for various purposes such as: - manufacturers of encoders, and the
20、ir customers, can use the tests to verify whether the encoder produces valid bit streams; - manufacturers of decoders and their customers can use the tests to verify whether the decoder meets the requirements specified in ETS 300 401 2 for the claimed decoder capabilities. ETSI 6 ETSI TS 1 O1 757 V1
21、.l.l (2000-06) 1 Scope The present document specifies how tests can be designed to verify whether bitstreams and decoders meet the requirements specified in ETS 300 401 2. In the present document, encoders are not addressed specifically. An encoder may be considered to be a DAB audio encoder if it g
22、enerates bitstreams compliant with the syntactic and semantic bitstream requirements specified in ETS 300 40 1 2. The characteristics of a bitstream such as the sampling frequency, mode and bit rate define the subset of the standard that is exploited in the bitstream. Decoder characteristics define
23、the properties and capabilities of the applied decoding process. An example of a property is the accuracy with which the PCM audio signal is reconstructed. The capabilities of a decoder specify which coded bitstreams the decoder can decode and reconstruct, by defining the subset of the standard that
24、 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 the conformance of decoders to the requirements defined i
25、n ETS 300 401 2. Bitstreams for conformance testing, which are available from Eureka 147, are described briefly, and there is an annex describing a test for the operation of dynamic range control (DRC) in receivers. The provision of DRC is optional. 2 References The following documents contain provi
26、sions which, through reference in this text, constitute provisions of the present document. References are either specific (identified by date of publication, edition number, version number, etc.) or non-specific. For a specific reference, subsequent revisions do not apply. For a non-specific refere
27、nce, the latest version applies. A non-specific reference to an ETS shall also be taken to refer to later versions published as an EN with the same number. il ISO/IEC 11 172-4 (1993): “Information technology - Coding of moving pictures and associated audio for digital storage media at up to about 1,
28、5 Mbitls - Part 4: Compliance testing“. ETSI ETS 300 401: “Radio broadcasting systems; Digital Audio Broadcasting (DAB) to mobile, portable and fixed receivers“. Gilchrist, N.H.C., 1994: “DRACULA: Dynamic range control for broadcasting and other applications“. BBC Research the audio test bitstreams
29、have to be transported using the DAB signal. In practice, this means that the DAB receiver has to be connected to a DAB chain. Error free bitstreams at the input of the audio decoder shall be ensured, and verified by monitoring the BER. A linear PCM (Le. decoded digital) output shall be available fr
30、om the DAB receiver, and the bitstream at the output of the decoder and the reference output shall be accurately aligned. If the receiver does not have a linear PCM output, a test point should be provided within the receiver, from which a decoded digital audio signal may be taken and converted into
31、a form suitable for connection to a workstation. The receiver manufacturer should ensure that such a test point is available and clearly identified in receivers submitted for testing, and (ideally) provide a conversion module suitable for interfacing to the workstation. ETSI 9 ETSI TS 1 O1 757 V1.l.
32、l (2000-06) stream Decoder under test difference data Figure 1 : Test configuration for a decoder with a digital output In receivers where D/A conversion is performed with a clock which is locked to the received bit clock, any buffering in the decoder should convey the decoded PCM signal to the D/A
33、converter unchanged except for the timing. In receivers using a free-running clock for D/A conversion, the management of buffering in the decoder may cause sample slipping to occur. It may be possible to prevent sample slipping by taking the D/A clock and locking the master clock for the DAB chain t
34、o this. To facilitate this, the receiver manufacturer should ensure that a suitable test point from which to obtain this clock is available in receivers submitted for testing. When the DAB audio is sampled at 24 kHz (LSF) some receivers may convert the sampling frequency to 48 kHz in the decoder pri
35、or to D/A conversion. Depending upon the nature of the sampling frequency up-conversion, it may, or may not, be possible to run the conformance tests with 24 kHz sampling by sub-sampling the decoded signal. 4.3 Audio decoder characteristics A DAB Audio decoder may support only specific values, or a
36、specific range, or a specific combination of values or ranges of the following parameters in audio bitstreams. These parameters are encoded directly or indirectly in the bitstream. a) bitrate-index (see subclause 7.2.1.3 of ETS 300 401 2); b) id (see subclause 7.2.1.3 of ETS 300 401 2); c) mode (see
37、 subclause 7.2.1.3 of ETS 300 401 2); d) mode-extension (see subclause 7.2.1.3 of ETS 300 401 2); e) dynamic range control (DRC) (see subclause 7.4.1 of ETS 300 401 2). A DAB Audio decoder shall be capable of handling error protection (crc-check and scf-crccheck) in order to conceal transmission err
38、ors. The method to be applied in the case of transmission errors is not standardized and depends on the specific implementation of a DAB audio decoder. The provision of dynamic range control (DRC) is not mandatory and the implementation of DRC in the decoder may differ between decoders. A method for
39、 testing dynamic range control in receiver decoders is described in annex A. Conformance of an audio decoder to ETS 300 401 2 requires that the output signal of the decoder is reconstructed accurately. Decoders that support all combinations are designated as Full DAB audio decoders. Other decoders m
40、ay be able to support at least one but not all of the options defined above. ETSI 10 ETSI TS 1 O1 757 V1.l.l (2000-06) 4.4 Requirements for audio bitstreams Bitstreams for DAB, including test bitstreams, shall conform to the following requirements: layer: the Layer field shall not be encoded with th
41、e binary values Olt, 1 1. bit-rate-index: the bitrate field shall not be encoded with the binary values 0000 and 1 11 1 sampling-frequency: the sampling frequency field is fixed to the binary value 01. padding: since no padding is necessary the value is fixed to O. emphasis: since no emphasis is all
42、owed this field is fixed to the binary value 00. protection-bit: this bit is fixed to O since error protection is mandatory, hence the correct CRC16 value shall be in the crc-check field. scalefactor: the scalefactorsb p or scalefactorch sb p field shall not refer to index 63. samples: for un-groupe
43、d samples the coded representation of subband samples the valid range is from zero up to (nlevels -2), where nlevels equals the number of levels used for quantization of that sample, that is the coded representation of a sample shall not consist of a bitstring with only 1s. For grouped samples the r
44、ange shall be from zero up to 26 if nlevels equals 3, from zero up to 124 if nlevels equals 5, and from zero up to 728 if nlevels equals 9. frame length (1): the bit allocation and the scalefactor select information shall be such that the total number of bits for a frame does not exceed the frame le
45、ngth. frame length (2): the frame length shall equal the number of slots times the slot size. The audio test bitstreams available from Eureka 147 and described in subclause 4.5 conform to these requirements. 4.5 Descriptions of the audio test bitstreams All bitstreams used to test the decoder capabi
46、lities are error free, fully compliant DAB Audio bitstreams as defined in ETS 300 401 2. All bitstreams carry a correct F-PAD, ISO-CRC and ScF-CRC field some bitstream are prepared for carrying X-PAD data field with variable length. This data is set to zero. Testing of the X-PAD field and its conten
47、t is beyond the scope of the present document. The bitstreams can be obtained from ftp:/ftp.worlddab.org/bitstreams. Compressed bitstreams are provided, according to ETS 300 401 2. Detailed descriptions of the bitstreams are furnished below. The following file name extensions are used to identify di
48、fferent parts: testXX.mpg: DAB audio bitstream; testXX.dec: reference output; testXX.txt: description file. Where XX stands for the bitstream number as indicated in table 1. ETSI 11 ETSI TS 1 O1 757 V1.l.l (2000-06) Table 1 : Characteristics of the test sequences feature Bitctream number 02 I 03 I 0
49、4 I 05 I 06 I 07 I 08 I 10 js: joint stereo; si: single channel. 4.5.1 Test bitstream #1 Specification: Channel #1: sine 0,4; 2,O; 3,2; 5,3; 6,s; 8,3; 9,s; 11,4; 13,O and 15,O kHz; -22,3 dl3. Channel #2: sine 0,3; 2,5; 33; 4,O; 7,O; 8,O; 10,5; 11,5; 14,O and 20,O kHz; -22,3 dl3. - - The mode is switched consecutively through the following set: stereo, joint stereo bound #1 to joint stereo bound #4. - The bitstream carries DRC information which covers the complete range of possible gain factors. The DRC data for the f
