1、 International Telecommunication Union ITU-T G.729.1TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU Amendment 7(02/2012) SERIES G: TRANSMISSION SYSTEMS AND MEDIA, DIGITAL SYSTEMS AND NETWORKS Digital terminal equipments Coding of voice and audio signals G.729-based embedded variable bit-rate coder:
2、An 8-32 kbit/s scalable wideband coder bitstream interoperable with G.729 Amendment 7: New Annex F with voice activity detector using ITU-T G.720.1 Annex A Recommendation ITU-T G.729.1 (2006) Amendment 7 ITU-T G-SERIES RECOMMENDATIONS TRANSMISSION SYSTEMS AND MEDIA, DIGITAL SYSTEMS AND NETWORKS INTE
3、RNATIONAL 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 INTERNATIONAL CARRIER TELEPHONE
4、 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 Coding of voice and a
5、udio signals G.710G.729Principal characteristics of primary multiplex equipment G.730G.739 Principal characteristics of second order multiplex equipment G.740G.749 Principal characteristics of higher order multiplex equipment G.750G.759 Principal characteristics of transcoder and digital multiplicat
6、ion equipment G.760G.769 Operations, administration and maintenance features of transmission equipment G.770G.779 Principal characteristics of multiplexing equipment for the synchronous digital hierarchy G.780G.789 Other terminal equipment G.790G.799 DIGITAL NETWORKS G.800G.899 DIGITAL SECTIONS AND
7、DIGITAL LINE SYSTEM G.900G.999 MULTIMEDIA QUALITY OF SERVICE AND PERFORMANCE GENERIC AND USER-RELATED ASPECTS G.1000G.1999 TRANSMISSION MEDIA CHARACTERISTICS G.6000G.6999 DATA OVER TRANSPORT GENERIC ASPECTS G.7000G.7999 PACKET OVER TRANSPORT ASPECTS G.8000G.8999 ACCESS NETWORKS G.9000G.9999 For furt
8、her details, please refer to the list of ITU-T Recommendations. Rec. ITU-T G.729.1 (2006)/Amd.7 (02/2012) i Recommendation ITU-T 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 7 New Annex F with voice activity
9、 detector using ITU-T G.720.1 Annex A Summary New Annex F introduced by Ammendment 7 of ITU-T G.729.1 describes the voice activity detector (VAD) to be used together with the DTX/CNG scheme of Annex C to provide the complete functionality of an ITU-T G.729.1 discontinuous transmission system. Since
10、the VAD algorithm described in Annex F is the same as in ITU-T G.720.1 Annex A, this annex makes reference to ITU-T G.720.1 Annex A for the parts of the description that are identical to the original Recommendation. The ANSI C source code in the electronic attachment to this text is an integral part
11、 of Annex F. History Edition Recommendation Approval Study Group 1.0 ITU-T G.729.1 2006-05-29 16 1.1 ITU-T G.729.1 (2006) Amd. 1 2007-01-13 16 1.2 ITU-T G.729.1 (2006) Amd. 2 2007-02-13 16 1.3 ITU-T G.729.1 (2006) Amd. 3 2007-08-29 16 1.4 ITU-T G.729.1 (2006) Amd. 4 2008-06-29 16 1.5 ITU-T G.729.1 (
12、2006) Amd. 5 2008-12-07 16 1.6 ITU-T G.729.1 (2006) Cor.1 2009-08-29 16 1.7 ITU-T G.729.1 (2006) Amd. 6 2010-03-29 16 1.8 ITU-T G.729.1 (2006) Amd. 7 2012-02-29 16 Keywords CNG, comfort noise generation, discontinuous transmission, DTX, G.729.1, VAD, voice activity detector, silence compression. ii
13、Rec. ITU-T G.729.1 (2006)/Amd.7 (02/2012) FOREWORD The International 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 o
14、rgan of ITU. ITU-T is responsible for studying technical, operating 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 th
15、e topics for study by the ITU-T study groups which, in turn, produce 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 ar
16、e prepared on a collaborative basis with ISO and IEC. NOTE In this 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 Recommendat
17、ion may contain certain mandatory provisions (to ensure, e.g., interoperability 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 use
18、d to express requirements. The use of such words does not suggest 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 Intellec
19、tual Property Right. ITU takes no position concerning the evidence, 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 noti
20、ce of intellectual property, protected by patents, which may be required 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 2
21、012 All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the prior written permission of ITU. Rec. ITU-T G.729.1 (2006)/Amd.7 (02/2012) iii Table of Contents Page Annex F Voice activity detector . 1 F.1 Scope 1 F.2 References 1 F.3 Definitions 1 F.4 Ab
22、breviations and acronyms 2 F.5 General description of ITU-T G.729.1 VAD algorithm . 2 F.6 Detailed description of the ITU-T G.729.1 VAD algorithm 3 F.7 Organization and use of the simulation software . 3 Bibliography. 4 Electronic attachment: Updated ANSI C source code Rec. ITU-T G.729.1 (2006)/Amd.
23、7 (02/2012) 1 Recommendation ITU-T 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 7 New Annex F with voice activity detector using ITU-T G.720.1 Annex A Annex F Voice activity detector (This annex forms an int
24、egral part of this Recommendation.) F.1 Scope This annex contains the description of the voice activity detector (VAD) to be used together with the DTX/CNG scheme of ITU-T G.729.1 Annex C to provide the complete functionality of the ITU-T G.729.1 discontinuous transmission system. This annex is orga
25、nized as follows. References, definitions, and abbreviations and acronyms used throughout this annex are defined in clauses F.2, F.3, and F.4, respectively. Clause F.5 gives a general description of the ITU-T G.729.1 VAD functionality including the input sampling rate, the operating frame length, th
26、e algorithmic delay, the configurations, and the complexity and memory cost. Description of the ITU-T G.729.1 VAD algorithm is given in clause F.6, making reference to the relevant parts of ITU-T G.720.1. Clause F.7 contains a description of the organization and use of the simulation software. F.2 R
27、eferences ITU-T G.720.1 Recommendation ITU-T G.720.1 (2010), Generic sound activity detector. ITU-T G.720.1 A1 Recommendation ITU-T G.720.1 (2010) Amendment 1 (2010), New Annex A on generic voice activity detection. F.3 Definitions F.3.1 Terms defined elsewhere This annex uses the following terms de
28、fined elsewhere: F.3.1.1 balanced operating point ITU-T G.720.1: Generic sound activity detector (GSAD) operating point that provides a middle point performance between the other two operating points in either voice activity detection or speech/music discrimination. F.3.1.2 bandwidth-saving operatin
29、g point ITU-T G.720.1: Generic sound activity detector (GSAD) operating point privileging accurate detection for background signals in voice activity detection, or privileging accurate detection for speech signals in speech/music discrimination. F.3.1.3 quality-preferred operating point ITU-T G.720.
30、1: Generic sound activity detector (GSAD) operating point privileging accurate detection for foreground signals in voice activity detection, or privileging accurate detection for music signals in speech/music discrimination. 2 Rec. ITU-T G.729.1 (2006)/Amd.7 (02/2012) F.3.2 Terms defined in this ann
31、ex F.3.2.1 frame: A segment of samples of 10 ms. F.3.2.2 superframe: A segment of samples of 20 ms. F.4 Abbreviations and acronyms This annex uses the abbreviations and acronyms defined in Table F.1. Table F.1 Glossary of acronyms Acronym Description CNG Comfort Noise Generation DTX Discontinuous Tr
32、ansmission RAM Random Access Memory ROM Read-Only Memory VAD Voice Activity Detection/Detector WMOPS Weighted Million Operations Per Second F.5 General description of ITU-T G.729.1 VAD algorithm The ITU-T G.729.1 VAD uses the same algorithm as ITU-T G.720.1 A1. Hence, this annex describes the adapta
33、tion of ITU-T G.720.1 Annex A for its use with the DTX/CNG algorithm of ITU-T G.729.1 Annex C, the latter having been introduced in Amendment 4. F.5.1 Input sampling rate The input sampling rates supported by Annex F are compliant with those of the ITU-T G.729.1 encoder, which makes the ITU-T G.729.
34、1 VAD compatible with any valid input to the ITU-T G.729.1 encoder. The default sampling rate is 16 000 Hz; the 8 000 Hz sampling rate is also supported. F.5.2 Operating frame size The ITU-T G.729.1 VAD operates on a 10-ms basis that is compliant with the operation of the ITU-T G.729.1 core layer en
35、coder. However, since the ITU-T G.729.1 DTX/CNG of Amendment 4 sends and receives an activity indication every 20 ms, the two activity indications for the two 10 ms frames within an ITU-T G.729.1 superframe are combined and then fed into the encoder. The combination rule is that a superframe will on
36、ly be indicated as active if both frames within a superframe are indicated as active. F.5.3 Delay The ITU-T G.729.1 VAD does not add extra delay to the ITU-T G.729.1 encoder. F.5.4 Operating points The ITU-T G.729.1 VAD is able to operate among three different operating points: bandwidth saving oper
37、ating point, quality-preferred operating point and balanced operating point. The bandwidth-saving operating point provides maximal bandwidth saving while minimizing the signal quality degradation, while the quality-preferred operating point provides higher quality for active signal with relatively l
38、ess bandwidth saving. The balanced operating point hence provides a balanced/optimal performance in between the two operating points. Selection of an operating point in the reference ANSI-C source code is made through the command line. Rec. ITU-T G.729.1 (2006)/Amd.7 (02/2012) 3 F.5.5 Complexity and
39、 memory cost The ITU-T G.729.1 VAD adds 2.397 WMOPS to the ITU-T G.729.1 encoder. This computational complexity was estimated using the basic operators of the 2005 version of the ITU-T Software Tool Library b-ITU-T G.191. The storage requirement is given in 16-bit words. In total, 837 words of addit
40、ional data ROM and 257 words of additional static RAM are necessary with respect to the ITU-T G.729.1 encoder. F.6 Detailed description of the ITU-T G.729.1 VAD algorithm The same as clause 7.1 of ITU-T G.720.1. F.7 Organization and use of the simulation software The ANSI-C source code simulating th
41、e bit-exact, fixed-point simulation software of ITU-T G.729.1 VAD is integrated into the ITU-T G.729.1 source code. The modification to the ITU-T G.729.1 source code updated the main function in G729EV_MAIN_encoder.c, the G729EV_MAIN_Encode function in G729EV_MAIN_encod.c/h, and integrated the VAD f
42、unctions as a static library into the ITU-T G.729.1 encoder project. The command line instruction for the encoder is as follows: encoder -options inputfile bitstreamfile The possible encoder options are listed below: dtx: Run encoder with DTX/CNG enabled; modeX: Run encoder with VAD in operating poi
43、nt X (X=0, 1 or 2, representing balanced or quality-preferred or bandwidth saving operating points, respectively); rXXXXX: Run encoder at XXXXX bit/s (by default: 32000); mXX: The maximum SID interval (by default: 25); f8: 8000 Hz sampled input (if not specified, 16000 Hz by default); g729b_bst: Run
44、 encoder at 8 kbit/s and generate bitstream in ITU-T G.729 Annex B format. By default, the input sampling rate is 16000 Hz and the bitstream is divided into 20 ms frames (or superframes). The command line for the decoder is as follows: decoder -options bitstreamfile outputfile The possible decoder o
45、ptions are listed below: rXXXXX: Run decoder with maximal bit rate XXXXXX bit/s (by default: 32000); f8: 8000 Hz sampled output (if not specified, 16000 Hz by default); ld: Low-delay mode (the decoder bit rate must be limited to 8 or 12 kbit/s); g729b_bst: Read and decode ITU-T G.729 Annex B bitstre
46、am. By default, the output sampling rate is 16000 Hz and the bitstream is divided into 20 ms frames (or superframes). The input file and output file are sampled data files containing 16-bit linear PCM signals. 4 Rec. ITU-T G.729.1 (2006)/Amd.7 (02/2012) Bibliography b-ITU-T G.191 Recommendation ITU-
47、T G.191 (2005), Software tools for speech and audio coding standardization. Printed in Switzerland Geneva, 2012 SERIES OF ITU-T RECOMMENDATIONS Series A Organization of the work of ITU-T Series D General tariff principles Series E Overall network operation, telephone service, service operation and h
48、uman factors Series F Non-telephone telecommunication services Series G Transmission systems and media, digital systems and networks Series H Audiovisual and multimedia systems Series I Integrated services digital network Series J Cable networks and transmission of television, sound programme and ot
49、her multimedia signals Series K Protection against interference Series L Construction, installation and protection of cables and other elements of outside plant Series M Telecommunication management, including TMN and network maintenance Series N Maintenance: international sound programme and television transmission circuits Series O Specifications of measuring equipment Series P Terminals and subjective and objective assessment methods Series Q Switching and signalling Series R Telegraph transmission Serie
