1、 International Telecommunication Union ITU-T G.718TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU Amendment 3(03/2013) SERIES G: TRANSMISSION SYSTEMS AND MEDIA, DIGITAL SYSTEMS AND NETWORKS Digital terminal equipments Coding of voice and audio signals Frame error robust narrow-band and wideband embe
2、dded variable bit-rate coding of speech and audio from 8-32 kbit/s Amendment 3: New Annex C describing an alternative floating-point implementation of the superwideband monaural extension Recommendation ITU-T G.718 (2008) Amendment 3 ITU-T G-SERIES RECOMMENDATIONS TRANSMISSION SYSTEMS AND MEDIA, DIG
3、ITAL SYSTEMS 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 I
4、NTERNATIONAL 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.
5、700G.709 Coding of voice and audio 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 tran
6、scoder 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 hierarchy G.780G.789 Other terminal equipment G.790G.799 DIGITAL NETWORKS G.
7、800G.899 DIGITAL SECTIONS AND 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
8、NETWORKS G.9000G.9999 For further details, please refer to the list of ITU-T Recommendations. Rec. ITU-T G.718 (2008)/Amd.3 (03/2013) i Recommendation ITU-T G.718 Frame error robust narrow-band and wideband embedded variable bit-rate coding of speech and audio from 8-32 kbit/s Amendment 3 New Annex
9、C describing an alternative floating-point implementation of the superwideband monaural extension Summary Amendment 3 to Recommendation ITU-T G.718 adds a new Annex C describing a floating-point implementation of the superwideband monaural extension as an alternative to the fixed-point implementatio
10、n described in Annex B. Annex C has as electronic attachments the reference ANSI C-source code and associated test vectors. The latter can be downloaded from the database for ITU-T Test Signals for Telecommunication Systems at http:/itu.int/net/ITU-T/sigdb/speaudio/Gseries.htm#G.718. History Edition
11、 Recommendation Approval Study Group 1.0 ITU-T G.718 2008-06-13 16 1.1 ITU-T G.718 (2008) Cor.1 2008-11-13 16 1.2 ITU-T G.718 (2008) Amd.1 2009-03-16 16 1.3 ITU-T G.718 (2008) Cor.2 2009-08-29 16 1.4 ITU-T G.718 (2008) Amd.2 2010-03-29 16 1.5 ITU-T G.718 (2008) Cor.3 2011-01-13 16 1.6 ITU-T G.718 (2
12、008) Amd.3 2013-03-16 16 ii Rec. ITU-T G.718 (2008)/Amd.3 (03/2013) 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 Secto
13、r (ITU-T) is a permanent organ 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
14、four years, establishes the 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,
15、the necessary standards are 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
16、. However, the Recommendation 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 ne
17、gative equivalents are used 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
18、 use of a claimed Intellectual 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 Recommendat
19、ion, ITU had received notice 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
20、.itu.int/ITU-T/ipr/. ITU 2013 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.718 (2008)/Amd.3 (03/2013) 1 Recommendation ITU-T G.718 Frame error robust narrow-band and wideband embedded variable b
21、it-rate coding of speech and audio from 8-32 kbit/s Amendment 3 New Annex C describing an alternative floating-point implementation of the superwideband monaural extension Add the following new Annex C to Recommendation ITU-T G.718 (2008). Annex C Reference floating-point implementation of the super
22、wideband monaural extension as an alternative to the fixed-point implementation described in Annex B (This annex forms an integral part of this Recommendation.) C.1 Scope This annex1describes an alternative floating-point implementation of the ITU-T G.718 Annex B (superwideband scalable extension fo
23、r ITU-T G.718) codec. It is fully interoperable with the ITU-T G.718 Annex B codec. This annex includes an electronic attachment containing the reference ANSI C source code for floating-point implementation, as well as the associated test vectors. C.2 Overview Annex B of ITU-T G.718 provides a bit-e
24、xact, fixed-point specification of an algorithm for extending the G.718 codec for superwideband speech and audio signals operating at the total bit rates of 36, 40 and 48 kbit/s. Exact details of these specifications are given in a bit-exact, fixed-point C-code available from ITU-T. This annex descr
25、ibes and defines implementation of the codec based on floating-point arithmetic as an alternative to the fixed-point implementation described in Annex B. C.3 Algorithm description This floating-point version of the ITU-T G.718 Annex B codec has the same algorithm steps as the fixed-point version. Si
26、milarly, the bitstream is identical to that of the ITU-T G.718 Annex B codec. For algorithmic details, see ITU-T G.718 Annex B. _ 1This annex contains an electronic attachment with the reference ANSI C-source code and associated test vectors. 2 Rec. ITU-T G.718 (2008)/Amd.3 (03/2013) C.4 ANSI C-code
27、 ANSI C-code simulating the floating-point version of the ITU-T G.718 Annex B codec defined in this annex has been developed and is available as an electronic attachment to this Recommendation. The ANSI C-code represents the normative specification of this annex. The algorithmic description given by
28、 the C-code shall take precedence over the text contained in the main body of this Recommendation. As of the approval of this text, the current version of this ANSI C-code is version 1.0 of January 2013. More recent versions may become available through corrigenda or amendments to this Recommendatio
29、n. It is important to use the latest available version from the ITU-T website. The structure of the floating-point source code faithfully follows the corresponding fixed-point source code. The code is written in ANSI-C. The codec is implemented as two separate programs: encoder options R input_audio
30、_file bitstream_file decoder options R bitstream_file output_audio_file where R is the input/output sampling rate in kHz. The following options are defined for the encoder: -maxBR : Maximum encoded bit rate 8000, 12000, 16000, 24000, 32000, 40000, 48000 (default) bps -G718_L4 : SWB layers on top of
31、G.718 layer 4 instead of layer 5; if defined, the maximum encoded bit rate can be 8000, 12000, 16000, 24000, 28000, 32000, 40000 (default) bps -quiet : Quiet processing -dtx D : DTX mode. Optional fixed update rate D = frames. Default rate - adaptive. -ns N : Noise reduction ON (default OFF). Maximu
32、m reduction N = dB, default N=14 dB -IO_G722_2 : G722.2 12.65 kbit/s interoperable bitstream The following options are defined for the decoder: -quiet : Quiet processing -truncate : Simulation of ITU “truncate“ tool, BR = 8000, 12000, 16000, 24000, 32000, 36000, 40000, 48000* (default) bps -maxBR :
33、Maximum decoded bit rate, BR = 8000, 12000, 16000 24000, 28000, 32000, 36000, 40000, 48000* (default) bps -disabled_NG : Noise gate deactivation -enabled_SP : Short pitch post-processing activation -IO_G722_2 : G722.2 interoperable bitstream (compatible with all G.722.2 rates) * Max and default bit
34、rates are limited to 40000 if option -G718_L4 is enabled in encoding operation. The codec directory structure is as follows: + /bin_msvc/ will be created for containing Microsoft Visual C+ 2008 executables. + /bin_cygwin/ will be created for containing Cygwin gcc executables. + /bin_linux/ will be c
35、reated for containing Linux gcc executables. + /src/lib_com/ contains source files used with the G.718 encoder and decoder. + /src/lib_dec/ contains source files used only with the G.718 decoder. + /src/lib_enc/ contains source files used only with the G.718 encoder. Rec. ITU-T G.718 (2008)/Amd.3 (0
36、3/2013) 3 + /src/SWB/ contains source files used only with the superwideband extension. + /src/music_enh_lib/ contains source files used only with the music enhancement. + /src/lib_wmops/ contains complexity estimation tools. + /src/wb_enc.c contains the main routine of the encoder. + /src/wb_dec.c
37、contains the main routine of the decoder. + /workspace/VC2008/ contains MSVC+ 2008 workspace “g718_swb.sln“ and projects. + /workspace/makefile is the Cygwin/Linux gcc makefile. The file format of the supplied binary data is 16-bit binary data which is read and written in 16-bit little-endian words.
38、 The bitstream follows the ITU-T G.192 format. For every 20-ms input speech frame, the bitstream contains the following 16-bit unsigned short integer data: SyncWord DataLen 1st Databit 2nd DataBit . . . Nth DataBit Each bit is presented as follows: Bit 0 = 0x007F, Bit 1 = 0x0081. The SyncWord from t
39、he encoder is always 0x6B21. The SyncWord 0x6B20 on the decoder side indicates that the frame was corrupted. The DataLen parameter gives the number of transmitted source bits in the frame. Printed in Switzerland Geneva, 2013 SERIES OF ITU-T RECOMMENDATIONS Series A Organization of the work of ITU-T
40、Series D General tariff principles Series E Overall network operation, telephone service, service operation and human 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 I
41、ntegrated services digital network Series J Cable networks and transmission of television, sound programme and other multimedia signals Series K Protection against interference Series L Construction, installation and protection of cables and other elements of outside plant Series M Telecommunication
42、 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 Tel
43、egraph transmission Series S Telegraph services terminal equipment Series T Terminals for telematic services Series U Telegraph switching Series V Data communication over the telephone network Series X Data networks, open system communications and security Series Y Global information infrastructure, Internet protocol aspects and next-generation networks Series Z Languages and general software aspects for telecommunication systems
