1、 International Telecommunication Union ITU-T G.729.1TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU Amendment 4(06/2008) SERIES G: TRANSMISSION SYSTEMS AND MEDIA, DIGITAL SYSTEMS AND NETWORKS Digital terminal equipments Coding of analogue signals by methods other than PCM G.729-based embedded variab
2、le bit-rate coder: An 8-32 kbit/s scalable wideband coder bitstream interoperable with G.729 Amendment 4: New Annex C (DTX/CNG scheme) plus corrections to main body and Annex B Recommendation ITU-T G.729.1 (2006) Amendment 4 ITU-T G-SERIES RECOMMENDATIONS TRANSMISSION SYSTEMS AND MEDIA, DIGITAL SYST
3、EMS AND NETWORKS INTERNATIONAL TELEPHONE CONNECTIONS AND CIRCUITS G.100G.199 GENERAL CHARACTERISTICS COMMON TO ALL ANALOGUE CARRIER-TRANSMISSION SYSTEMS G.200G.299 INDIVIDUAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON METALLIC LINES G.300G.399 GENERAL CHARACTERISTICS OF INTERNATIO
4、NAL CARRIER TELEPHONE SYSTEMS ON RADIO-RELAY OR SATELLITE LINKS AND INTERCONNECTION WITH METALLIC LINES G.400G.449 COORDINATION OF RADIOTELEPHONY AND LINE TELEPHONY G.450G.499 TRANSMISSION MEDIA AND OPTICAL SYSTEMS CHARACTERISTICS G.600G.699 DIGITAL TERMINAL EQUIPMENTS G.700G.799 General G.700G.709
5、Coding of analogue signals by pulse code modulation G.710G.719 Coding of analogue signals by methods other than PCM G.720G.729 Principal characteristics of primary multiplex equipment G.730G.739 Principal characteristics of second order multiplex equipment G.740G.749 Principal characteristics of hig
6、her order multiplex equipment G.750G.759 Principal characteristics of transcoder and digital multiplication equipment G.760G.769 Operations, administration and maintenance features of transmission equipment G.770G.779 Principal characteristics of multiplexing equipment for the synchronous digital hi
7、erarchy G.780G.789 Other terminal equipment G.790G.799 DIGITAL NETWORKS G.800G.899 DIGITAL SECTIONS AND DIGITAL LINE SYSTEM G.900G.999 QUALITY OF SERVICE AND PERFORMANCE GENERIC AND USER-RELATED ASPECTS G.1000G.1999 TRANSMISSION MEDIA CHARACTERISTICS G.6000G.6999 DATA OVER TRANSPORT GENERIC ASPECTS
8、G.7000G.7999 PACKET OVER TRANSPORT ASPECTS G.8000G.8999ACCESS NETWORKS G.9000G.9999 For further details, please refer to the list of ITU-T Recommendations. Rec. ITU-T G.729.1 (2006)/Amd.4 (06/2008) i Recommendation ITU-T G.729.1 G.729-based embedded variable bit-rate coder: An 8-32 kbit/s scalable w
9、ideband coder bitstream interoperable with G.729 Amendment 4 New Annex C (DTX/CNG scheme) plus corrections to main body and Annex B Summary This Recommendation describes an 8-32 kbit/s scalable wideband speech and audio coding algorithm interoperable with G.729, G.729A and G.729B. The output of the
10、G.729EV coder has a bandwidth of 50-4000 Hz at 8 and 12 kbit/s and 50-7000 Hz from 14 to 32 kbit/s. At 8 kbit/s, G.729EV is fully interoperable with G.729, Annex A/G.729 and Annex B/G.729. Hence, an efficient deployment in existing G.729-based VoIP infrastructures is foreseen. The coder operates on
11、20 ms frames and has an algorithmic delay of 48.9375 ms. By default, the encoder input and decoder output are sampled at 16 kHz. The encoder produces an embedded bitstream structured in 12 layers corresponding to 12 available bit rates from 8 to 32 kbit/s. The bitstream can be truncated at the decod
12、er side or by any component of the communication system to adjust “on the fly“ the bit rate to the desired value with no need for outband signalling. The underlying algorithm is based on a three-stage coding structure: embedded Code-Excited Linear Prediction (CELP) coding of the lower band (50-4000
13、Hz), parametric coding of the higher band (4000-7000 Hz) by Time-Domain Bandwidth Extension (TDBWE), and enhancement of the full band (50-7000 Hz) by a predictive transform coding technique referred to as Time-Domain Aliasing Cancellation (TDAC). Amendment 1 introduces the new Annex A containing the
14、 RTP payload format, capability identifiers and parameters for signalling of G.729.1 capabilities using H.245. Both format and capability parameters are fully compatible with the corresponding G.729.1 RTP definitions to allow seamless interoperability. Besides the new Annex, Amendment 1 to G.729.1 i
15、ncorporates changes needed to correct defects in G.729.1 and provides new, more comprehensive test vectors. Amendment 2 introduces the new Annex B, which defines an alternative implementation of the G.729.1 algorithm using floating point arithmetic to be used for implementation on DSP hardware optim
16、ized for floating-point operations. The accompanying floating point C-code is fully interoperable with the fixed-point C-code. Amendment 3 extends the low-delay functionality of main body and Annex B to the first wideband bit rate (14 kbit/s). It also incorporates changes needed to correct defects i
17、n the text and C-code of G.729.1 main body and Annex B. Amendment 4 introduces a new Annex C specifying a discontinuous transmission (DTX) and comfort noise generation for G.729.1. With this annex, the G.729.1 encoder is capable of generating a silence insertion description (SID) each time an update
18、 of the ambient background noise parameters is required to maintain the quality of the generated background noise. The SID information includes a core lower band layer, which can be decoded by the decoder of Annex B/G.729, an enhancement lower band layer and a higher band layer. The non-transmission
19、 between SID updates and the small size of the SID provide a significant reduction of bandwidth during inactive segments. Besides this new annex, Amendment 4 incorporates changes needed to correct defects identified in G.729.1 C source code (main body and Annex B), provides a revised set of test vec
20、tors, and updates the complexity figures table of G.729.1 text. Source Amendment 4 to Recommendation ITU-T G.729.1 (2006) was approved on 29 June 2008 by ITU-T Study Group 16 (2005-2008) under the Recommendation ITU-T A.8 procedure. ii Rec. ITU-T G.729.1 (2006)/Amd.4 (06/2008) FOREWORD The Internati
21、onal Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications, information and communication technologies (ICTs). The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of ITU. ITU-T is responsible for studying technical, operat
22、ing and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis. The World Telecommunication Standardization Assembly (WTSA), which meets every four years, establishes the topics for study by the ITU-T study groups which, in turn, pro
23、duce Recommendations on these topics. The approval of ITU-T Recommendations is covered by the procedure laid down in WTSA Resolution 1. In some areas of information technology which fall within ITU-Ts purview, the necessary standards are prepared on a collaborative basis with ISO and IEC. NOTE In th
24、is Recommendation, the expression “Administration“ is used for conciseness to indicate both a telecommunication administration and a recognized operating agency. Compliance with this Recommendation is voluntary. However, the Recommendation may contain certain mandatory provisions (to ensure e.g. int
25、eroperability or applicability) and compliance with the Recommendation is achieved when all of these mandatory provisions are met. The words “shall“ or some other obligatory language such as “must“ and the negative equivalents are used to express requirements. The use of such words does not suggest
26、that compliance with the Recommendation is required of any party. INTELLECTUAL PROPERTY RIGHTS ITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual Property Right. ITU takes no position concerning the evidence
27、, validity or applicability of claimed Intellectual Property Rights, whether asserted by ITU members or others outside of the Recommendation development process. As of the date of approval of this Recommendation, ITU had received notice of intellectual property, protected by patents, which may be re
28、quired to implement this Recommendation. However, implementers are cautioned that this may not represent the latest information and are therefore strongly urged to consult the TSB patent database at http:/www.itu.int/ITU-T/ipr/. ITU 2009 All rights reserved. No part of this publication may be reprod
29、uced, by any means whatsoever, without the prior written permission of ITU. Rec. ITU-T G.729.1 (2006)/Amd.4 (06/2008) iii CONTENTS Page 1 Scope 1 2 References. 1 3 Abbreviations 2 4 Notations and conventions 2 5 General description of the coder. 5 5.1 Encoder. 5 5.2 Decoder. 6 5.3 Frame erasure conc
30、ealment (FEC) . 8 5.4 Coder modes. 8 5.5 Bit allocation to coder parameters and bitstream layer format. 9 5.6 Algorithmic delay. 11 5.7 Computational complexity and storage requirement 11 5.8 Coder description 11 6 Functional description of the encoder. 11 6.1 QMF analysis filterbank, signal downsca
31、ling and spectral folding of the higher band . 11 6.2 Pre-processing of lower band . 13 6.3 Narrowband embedded CELP encoder (Layers 1 and 2). 13 6.4 Pre-processing of the higher band 24 6.5 TDBWE encoder (Layer 3) 24 6.6 TDAC encoder (Layers 4 to 12). 29 7 Functional description of the decoder. 40
32、7.1 Narrowband embedded CELP decoder (Layers 1 and 2). 40 7.2 TDBWE decoder (Layer 3) 41 7.3 TDAC decoder (Layers 4 to 12). 49 7.4 Post-filtering of the lower band 57 7.5 Spectral folding of higher band, signal upscaling and QMF synthesis filterbank. 58 7.6 Frame erasure concealment 60 7.7 Bit-rate
33、switching . 73 8 Description of the transmitted parameter indices . 75 9 Bit-exact description of the G.729EV coder. 77 9.1 Use of the simulation software. 77 9.2 Organization of the simulation software 78 iv Rec. ITU-T G.729.1 (2006)/Amd.4 (06/2008) Page Annex A Packet format, capability identifier
34、s and capability parameters 85 A.1 References 85 A.2 Packet structure for G.729.1 frames. 85 A.3 Capability identifiers and parameters for use with ITU-T Rec. H.245 85 A.4 Interoperability with ITU-T Rec. G.729. 87 Annex B Reference floating-point implementation for G.729.1 88 B.1 Scope 88 B.2 Refer
35、ences 88 B.3 Overview 88 B.4 Algorithmic description 88 B.5 ANSI C Code 88 Annex C DTX/CNG scheme 91 C.1 Scope 91 C.2 References 91 C.3 Definitions 91 C.4 Abbreviations and acronyms 91 C.5 Conventions 91 C.6 General description of the DTX, SID and CNG components 96 C.7 Functional description of the
36、silence compression encoder. 100 C.8 Functional description of the silence compression decoder. 107 C.9 Memory update. 114 C.10 Description of the transmitted parameter indices. 114 C.11 Bit-exact description of the silence compression of G.729.1. 115 Electronic attachment C source code and test vec
37、tors Rec. ITU-T G.729.1 (2006)/Amd.4 (06/2008) 1ITU-T Recommendation G.729.1 G.729-based embedded variable bit-rate coder: An 8-32 kbit/s scalable wideband coder bitstream interoperable with G.729 Amendment 4 New Annex C (DTX/CNG scheme) plus corrections to main body and Annex B 1 Scope This Recomme
38、ndation contains the description of an algorithm extending ITU-T Rec. G.729 for the scalable coding of narrowband and wideband speech and audio signals at 8-32 kbit/s. This Recommendation is organized as follows. The references, abbreviations and notations used throughout this Recommendation are def
39、ined in clauses 2, 3 and 4, respectively. Clause 5 gives a general outline of the G.729EV algorithm. The G.729EV encoder and decoder principles are discussed in clauses 6 and 7, respectively. The transmitted parameters are presented in clause 8. Clause 9 describes the software that defines this code
40、r in 16-32 bits fixed-point arithmetic. 2 References The following ITU-T Recommendations and other references contain provisions which, through reference in this text, constitute provisions of this Recommendation. At the time of publication, the editions indicated were valid. All Recommendations and
41、 other references are subject to revision; users of this Recommendation are therefore encouraged to investigate the possibility of applying the most recent edition of the Recommendations and other references listed below. A list of the currently valid ITU-T Recommendations is regularly published. Th
42、e reference to a document within this Recommendation does not give it, as a stand-alone document, the status of a Recommendation. ITU-T Recommendation G.191 (2005), Software tools for speech and audio coding standardization. ITU-T Recommendation G.192 (1996), A common digital parallel interface for
43、speech standardization activities. ITU-T Recommendation G.729 (1996), Coding of speech at 8 kbit/s using conjugate-structure algebraic-code-excited linear prediction (CS-ACELP). ITU-T Recommendation G.729 Annex A (1996), Reduced complexity 8 kbit/s CS-ACELP speech codec. ITU-T Recommendation G.729 A
44、nnex B (1996), A silence compression scheme for G.729 optimized for terminals conforming to Recommendation V.70. Rec. ITU-T G.729.1 (2006)/Amd.4 (06/2008) 2 3 Abbreviations The acronyms used in this Recommendation are summarized in Table 1. Table 1 Glossary of acronyms Acronym Description ACELP Alge
45、braic CELP BWE BandWidth Extension CELP Code-Excited Linear Prediction CNG Comfort Noise Generator DEMUX DEMUltipleXer DTX Discontinuous Transmission FEC Frame Erasure Concealment FIR Finite Impulse Response FFT Fast Fourier Transform G.729EV G.729 Embedded Variable bit rate HB Higher Band HPF High
46、Pass Filter IIR Infinite Impulse Response IP Internet Protocol LB Lower-Band LP Linear Prediction LPF Low Pass Filter LSB Least Significant Bit LSF Line Spectrum Frequency LSP Line Spectrum Pair LTP Long-Term Prediction MDCT Modified Discrete Cosine Transform MSB Most Significant Bit MUX MUltipleXer
47、 PCM Pulse Code Modulation QMF Quadrature Mirror Filterbank SID Silence Insertion Descriptor TDAC Time-Domain Aliasing Cancellation TDBWE Time-Domain BandWidth Extension VoIP Voice over IP VQ Vector Quantization WB Wideband WMOPS Weighted Million Operations Per Second 4 Notations and conventions To
48、be consistent with the text of ITU-T Rec. G.729, the 20 ms frames used by G.729EV will be referred to as superframes, whereas the 10 ms frames and the 5 ms subframes involved in the CELP processing will be respectively called frames and subframes. Rec. ITU-T G.729.1 (2006)/Amd.4 (06/2008) 3Throughou
49、t this Recommendation, the G.729 notations are reused. The notational conventions are detailed below: Codebooks are denoted by calligraphic characters (e.g., ). Time-domain signals are denoted by their symbol and a sample index between parenthesis, e.g., s(n). The variable n is used as sample index. Frequency-domain transforms are denoted by converting the related time-domain signal to capital letters, e.g., S(k) is the transform of s(n). The variable k is used as coefficient index. Superscript indices between parentheses (e.g
