1、 International Telecommunication Union ITU-T G.719TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU (06/2008) SERIES G: TRANSMISSION SYSTEMS AND MEDIA, DIGITAL SYSTEMS AND NETWORKS Digital terminal equipments Coding of analogue signals Low-complexity, full-band audio coding for high-quality, conversat
2、ional applications Recommendation ITU-T G.719 ITU-T G-SERIES RECOMMENDATIONS TRANSMISSION SYSTEMS AND MEDIA, DIGITAL SYSTEMS AND NETWORKS INTERNATIONAL TELEPHONE CONNECTIONS AND CIRCUITS G.100G.199 GENERAL CHARACTERISTICS COMMON TO ALL ANALOGUE CARRIER-TRANSMISSION SYSTEMS G.200G.299 INDIVIDUAL CHAR
3、ACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON METALLIC LINES G.300G.399 GENERAL CHARACTERISTICS OF INTERNATIONAL 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 TRA
4、NSMISSION MEDIA AND OPTICAL SYSTEMS CHARACTERISTICS G.600G.699 DIGITAL TERMINAL EQUIPMENTS G.700G.799 General G.700G.709 Coding of analogue signals G.710G.729 Principal characteristics of primary multiplex equipment G.730G.739 Principal characteristics of second order multiplex equipment G.740G.749
5、Principal characteristics of higher 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 equipmen
6、t for the synchronous digital hierarchy 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
7、 OVER TRANSPORT GENERIC ASPECTS 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.719 (06/2008) i Recommendation ITU-T G.719 Low-complexity, full-band audio coding for high-quality,
8、 conversational applications Summary Recommendation ITU-T G.719 describes the G.719 coding algorithm for low-complexity full-band conversational speech and audio, operating from 32 kbit/s up to 128 kbit/s. The encoder input and decoder output are sampled at 48 kHz. The codec enables full bandwidth,
9、from 20 Hz to 20 kHz, encoding of speech, music and general audio content. The codec operates on 20-ms frames and has an algorithmic delay of 40 ms. The coding algorithm is based on transform coding with adaptive time-resolution, adaptive bit-allocation and low-complexity lattice vector quantization
10、. This Recommendation contains an electronic attachment containing a set of test signals, which can be used together with the ANSI-C code in order to verity bit-exactness. Amendment 1 adds new Annex A that specifies the use of the ISO base media file format as container for the G.719 bitstream addre
11、sses non-conversational use cases of the codec (e.g., call waiting music playback and recording of teleconferencing sessions, voice mail messages, online “jam“-sessions). Amendment 1 also includes Annex B, an alternative implementation of the G.719 using floating-point arithmetic. Examples of applic
12、ation of the floating point implementations include DSP platforms optimized for floating point and codec implementations using desktop computers. Amendment 2 adds new Annex C specifying the G.719 packet format, capability identifier and capability parameters and related procedures for H.245 based sy
13、stems. Source Recommendation ITU-T G.719 was approved on 13 June 2008 by ITU-T Study Group 16 (2005-2008) under Recommendation ITU-T A.8 procedure. This edition includes the amendments approved on 13 November 2008 and 16 March 2009 by ITU-T Study Group 16 (2009-2012) under Recommendation ITU-T A.8 p
14、rocedure. Keywords Adaptive time-frequency transform, fast lattice vector quantization, full-band, low-complexity. ii Rec. ITU-T G.719 (06/2008) FOREWORD The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications, information and commu
15、nication technologies (ICTs). The ITU Telecommunication Standardization Sector (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. Th
16、e World Telecommunication Standardization Assembly (WTSA), which meets every 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
17、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 this Recommendation, the expression “Administration“ is used for conciseness to indicate both a telecommunication administration and a
18、recognized operating agency. Compliance with this Recommendation is voluntary. 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. Th
19、e 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 that compliance with the Recommendation is required of any party. INTELLECTUAL PROPERTY RIGHTS ITU draws attention to the possibility
20、 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, validity or applicability of claimed Intellectual Property Rights, whether asserted by ITU members or others outside of the Recomme
21、ndation development process. As of the date of approval of this Recommendation, 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 a
22、re 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 reproduced, by any means whatsoever, without the prior written permission of ITU. Rec. ITU-T G.719 (06/2008) iii CONTENTS Page 1 Scope 1 2
23、References. 1 3 Definitions 2 4 Abbreviations and acronyms 2 5 Notations and conventions 2 6 General description of the codec 4 6.1 Encoder. 4 6.2 Decoder. 5 6.3 Algorithmic delay analysis. 6 6.4 Complexity and memory requirements 6 6.5 Description of the codec. 7 7 Functional description of the enc
24、oder. 7 7.1 Transient detection . 7 7.2 Adaptive time-frequency transform . 9 7.3 Grouping of spectral coefficients . 14 7.4 Norm estimation and quantization 17 7.5 Bit allocation 18 7.6 Fast lattice vector quantization. 21 7.7 Noise level adjustment . 26 7.8 Bit stream format 27 8 Functional descri
25、ption of the decoder. 28 8.1 Flags decoding 28 8.2 Norm decoding . 28 8.3 Spectral coefficient decoding . 28 8.4 Spectrum filling 29 8.5 Inverse transform 31 8.6 Frame erasure concealment 34 9 Flexible rate selection. 34 10 Simulation software 35 10.1 Use of the simulation software. 35 10.2 Organiza
26、tion of the simulation software 35 Annex A Storage format definitions . 39 A.1 Scope 39 A.2 Raw storage format for the ITU-T G.719 bitstream. 39 A.3 Sample entry description for ISO base file format. 40 Annex B Floating point implementation. 43 B.1 Scope 43 iv Rec. ITU-T G.719 (06/2008) Page B.2 Alg
27、orithmic description 43 B.3 ANSI C code. 43 Annex C Packet format, capability identifier and capability parameters . 47 C.1 Packet structure for G.719 frames 47 C.2 Capability identifiers and parameters for use with ITU-T H.245 47 Bibliography. 50 Electronic attachment: Test signals Rec. ITU-T G.719
28、 (06/2008) 1 Recommendation ITU-T G.719 Low-complexity, full-band audio coding for high-quality, conversational applications11 Scope This Recommendation contains the description of a coding algorithm for full-band speech and audio signals at 32-128 kbit/s. The text of the Recommendation is organized
29、 as follows. The references, definitions, abbreviations and notations used throughout this Recommendation are defined in clauses 2, 3, 4 and 5, respectively. Clause 6 gives a general outline of the G.719 full-band algorithm. The G.719 full-band encoder and decoder principles are discussed in clauses
30、 7 and 8, respectively. Rates and operating points are provided in clause 9. Clause 10 describes the software that defines this coder in 16-32 bit fixed-point arithmetic. Annex A gives the storage format definitions. Annex B describes the floating point implementation and Annex C specifies the packe
31、t format, capability identifier and capability parameters. 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
32、Recommendations and 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 regu
33、larly published. The reference to a document within this Recommendation does not give it, as a stand-alone document, the status of a Recommendation. ITU-T G.191 Recommendation ITU-T G.191 (2005), Software tools for speech and audio coding standardization. ITU-T G.192 Recommendation ITU-T G.192 (1996
34、), A common digital parallel interface for speech standardization activities. ITU-T G.722.1 Recommendation ITU-T G.722.1 (2005), Low-complexity coding at 24 and 32 kbit/s for hands-free operation in systems with low frame loss. ITU-T H.245 Recommendation ITU-T H.245 (2008), Control protocol for mult
35、imedia communication. IETF RFC 3550 IETF RFC 3550 (2003), RTP: A Transport Protocol for Real-Time Applications. IETF RFC 5404 IETF RFC 5404 (2009), RTP Payload format for G.719. ISO/IEC 14496-12 ISO/IEC 14496-12:2008, Information technology Coding of audio-visual objects Part 12: ISO base media file
36、 format. ISO/IEC 15444-12 ISO/IEC 15444-12:2008, Information technology JPEG 2000 image coding system Part 12: ISO base media file format. _ 1This Recommendation contains an electronic attachment containing a set of test signals, which can be used together with the ANSI-C code in order to verity bit
37、-exactness. 2 Rec. ITU-T G.719 (06/2008) 3 Definitions None. 4 Abbreviations and acronyms This Recommendation uses the abbreviations and acronyms that are summarized in Table 1. Table 1 Abbreviations and acronyms Abbreviation Description BWE BandWidth Extension DCT Discrete Cosine Transform FB Full
38、Band FFT Fast Fourier Transform FLVQ Fast Lattice Vector Quantization IIR Infinite Impulse Response LVQ Lattice Vector Quantization MDCT Modified Discrete Cosine Transform MLT Modulated Lapped Transform MSE Mean Squared Error PDF Probability Density Function RAM Random Access Memory ROM Read Only Me
39、mory SNR Signal-to-Noise Ratio TDA Time Domain Aliasing WMOPS Weighted Million of Operations Per Second 5 Notations and conventions Table 2 lists the most relevant symbols used throughout this Recommendation. Table 2 Glossary of most relevant symbols Symbol Description x(n) Input signal sampled at 4
40、8 kHz HHp(z) High-pass filter used for the transient detection xHP(n) Output of the high-pass filter HHp(z) m Index of sub-frame E(m) Signals short-term energy corresponding to the m-th sub-frame ELT(m) Signals long-term energy corresponding to the m-th sub-frame Forgetting factor for computing ELT(
41、m) Energy ratio threshold xOLD(n) Input signal from the previous 20-ms frame h(n) Window function for transform xw(n) Windowed signal with h(n) Rec. ITU-T G.719 (06/2008) 3 Table 2 Glossary of most relevant symbols Symbol Description xTDA output signal matrix wx Windowed signal matrix ILIdentity mat
42、rices of order L JLTime reversal matrices of order L )(nx TDA output signal QmaxNormalization index for signal pre-scaling and post-scaling )(nx Scaled TDA signal )(kySpectral coefficients of the input frame L Frame length in samples v(n) Reordered signal z(n) Complex sequence of TDA signal )(pz Pre
43、-modulated complex sequence of TDA signal )(qZ Scaled inverse complex Fourier transform of )(pz )(ky Spectrum corresponds to )(nx p Index of sub-vector LpLength of the p-th sub-vector spStarting index of the spectral coefficients forming the p-th sub-vector epEnding index of the spectral coefficient
44、s forming the p-th sub-vector N(p) Norm or spectrum energy of the p-th sub-vector IN(p) Index of the p-th quantized norm IN(p) Differential index between IN(p+1) and IN(p) Spe(p) Spectrum function BSpe(p) Remapped spectrum function BMAXMaximum number of bands for spectral mapping bands, 20. HbLinear
45、 mapping slope for spectrum remapping TbLinear mapping offset for spectrum remapping JbSet of indices for spectrum remapping A(b) Pseudo-absolute threshold of hearing WSpe(p) Offset spectrum for norm adjustment )(pIqNIndex of the p-th adjusted quantized norm )( pIqNIndex of the p-th quantized norm G
46、 Generator matrix for the lattice D8 Index set of transform coefficients allocated zero bits tTransition frequency )(kzqReconstructed transform coefficients 4 Rec. ITU-T G.719 (06/2008) Table 2 Glossary of most relevant symbols Symbol Description )(kyqDecoded normalized transform coefficients )(nxqR
47、econstructed TDA signal qwmxReconstructed TDA signal matrix for sub-frame m R(p) Bit-allocation vector Number of remainder bits Bit budget yp,lThe l-th 8-dimensional vector belonging to the p-th sub-vector Optimal scaling factor in LVQ1 (p) Optimal scaling vector in LVQ2 for the p-th sub-vector The
48、notational conventions are detailed below: Time-domain signals are denoted by their symbol and a sample index between parentheses, 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) i
49、s the transform of s(n). The variable k is used as coefficient index. Superscript indices between parentheses (e.g., g(m)(n) are used to indicate time-dependency of variables. The variable m refers, depending on the context, to either a frame or sub-frame index, and the variable n to a sample index. Parameter ranges are given between square brackets, and include the boundaries (e.g., 0.6, 0.9). The sign function gives the polarity of the value and is denoted as sgn(x), wh
