1、 ETSI TS 126 447 V14.0.0 (2017-04) Universal Mobile Telecommunications System (UMTS); LTE; Codec for Enhanced Voice Services (EVS); Error concealment of lost packets (3GPP TS 26.447 version 14.0.0 Release 14) TECHNICAL SPECIFICATION ETSI ETSI TS 126 447 V14.0.0 (2017-04)13GPP TS 26.447 version 14.0.
2、0 Release 14Reference RTS/TSGS-0426447ve00 Keywords LTE,UMTS ETSI 650 Route des Lucioles F-06921 Sophia Antipolis Cedex - FRANCE Tel.: +33 4 92 94 42 00 Fax: +33 4 93 65 47 16 Siret N 348 623 562 00017 - NAF 742 C Association but non lucratif enregistre la Sous-Prfecture de Grasse (06) N 7803/88 Imp
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9、447 version 14.0.0 Release 14Intellectual 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 00
10、0 314: “Intellectual Property Rights (IPRs); Essential, or potentially Essential, IPRs notified to ETSI in respect of ETSI standards“, which is available from the ETSI Secretariat. Latest updates are available on the ETSI Web server (https:/ipr.etsi.org/). 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 000 314 (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 ETSI 3rd Generation Partnership Project (3GPP). The present document may refer to technical specifications or reports using their 3GPP identities, UMTS identities or GSM identities. These should be interpreted as being references to the corresponding ETSI deliverables
13、. The cross reference between GSM, UMTS, 3GPP and ETSI identities can be found under http:/webapp.etsi.org/key/queryform.asp. Modal verbs terminology In the present document “shall“, “shall not“, “should“, “should not“, “may“, “need not“, “will“, “will not“, “can“ and “cannot“ are to be interpreted
14、as described in clause 3.2 of the ETSI Drafting Rules (Verbal forms for the expression of provisions). “must“ and “must not“ are NOT allowed in ETSI deliverables except when used in direct citation. ETSI ETSI TS 126 447 V14.0.0 (2017-04)33GPP TS 26.447 version 14.0.0 Release 14Contents Intellectual
15、Property Rights 2g3Foreword . 2g3Modal verbs terminology 2g3Foreword . 6g31 Scope 7g32 References 7g33 Definitions, symbols and abbreviations . 7g33.1 Definitions 7g33.2 Symbols 7g33.3 Abbreviations . 8g34 General . 8g35 Detailed description 9g35.1 Concealment operation related to signal classificat
16、ion. 9g35.1.1 Overview 9g35.1.2 Signal class estimation 9g35.2 Concealment operation related to spectral envelope (LPC) representation 12g35.2.1 Specifics to rates 9.6, 16.4 and 24.4kbps 13g35.2.2 Specifics to AMR-WB IO mode . 13g35.2.3 Check for Mid LSF stability . 13g35.2.4 Adaptive interpolation
17、of LSFs . 14g35.2.5 LPC gain compensation 15g35.3 Concealment operation related to ACELP modes 16g35.3.1 General 16g35.3.1.1 Extrapolation of future pitch . 16g35.3.1.2 Construction of the periodic part of the excitation 18g35.3.1.2.1 Particularity of rate 5.9, 7.2, 8.0 and 13.2 kbps . 19g35.3.1.3 G
18、lottal pulse resynchronization . 19g35.3.1.3.1 Condition to perform resynchronisation 19g35.3.1.3.2 Performing glottal pulse resynchronization . 19g35.3.1.4 Construction of the random part of the excitation . 21g35.3.1.5 Spectral envelope concealment, synthesis and updates . 22g35.3.1.5.1 Specifics
19、for rates 9.6, 16.4 and 24.4 kbps 22g35.3.1.6 GSC mode concealment 22g35.3.1.7 Specifics for AMR-WB IO modes 22g35.3.1.8 Reconstructed excitation . 24g35.3.1.8.1 Particularity of rate 5.9, 7.2, 8.0 and 13.2 kbps . 24g35.3.2 Concealment for bandwidth extension for ACELP modes . 24g35.3.2.1 Time domai
20、n bandwidth extension . 24g35.3.2.1.1 SWB time domain bandwidth extension . 24g35.3.2.1.1.1 The reconstruction of the global frame gain 25g35.3.2.1.1.2 The reconstruction of the gain attenuation factor . 26g35.3.2.1.1.3 Specifics for rates 13.2 and 32 kbps 28g35.3.3 Guided concealment and recovery 2
21、9g35.3.3.1 Specifics for rate 24.4 kbps . 29g35.3.3.2 Specifics for rates 9.6, 16.4 and 24.4 kbps 29g35.3.3.3 Energy control during recovery. 30g35.3.3.4 Specifics for rates 32 and 64 kbps . 33g35.3.3.4.1 Adaptive codebook resynchronization and fast recovery (WB) 33g35.3.3.4.1.1 Decoding glottal pul
22、se position 33g35.3.3.4.1.2 Performing glottal pulse resynchronization . 33g35.3.3.4.2 Artificial onset reconstruction . 34g35.3.4 Handling of multiple frame losses and muting . 35g35.3.4.1 Specifics for rates 5.9, 6.8, 8.0, 13.2, 32 and 64 kbps . 35g3ETSI ETSI TS 126 447 V14.0.0 (2017-04)43GPP TS 2
23、6.447 version 14.0.0 Release 145.3.4.2 Specifics for rates 9.6, 16.4 and 24.4 kbps 36g35.3.4.2.1 Fading to background level . 36g35.3.4.2.2 Fading to background spectral shape . 37g35.3.4.2.3 Fading speed 37g35.4 Concealment operation related to MDCT modes . 38g35.4.1 PLC method selection . 38g35.4.
24、2 TCX MDCT 38g35.4.2.1 PLC method selection . 38g35.4.2.2 TCX time domain concealment. 40g35.4.2.2.1 Construction of the periodic part of the excitation 40g35.4.2.2.2 Construction of the random part of the excitation . 41g35.4.2.2.3 Construction of the total excitation, synthesis and updates . 42g35
25、.4.2.3 MDCT frame repetition with sign scrambling 42g35.4.2.4 Tonal MDCT concealment using phase prediction . 42g35.4.2.4.1 Overview . 42g35.4.2.4.2 Peak detection of tonal components 43g35.4.2.4.3 Phase prediction. 45g35.4.2.5 Non-tonal concealment with waveform adjustment 46g35.4.2.5.1 Preliminary
26、 concealment in frequency domain . 46g35.4.2.5.2 Waveform adjustment in time domain 47g35.4.2.6 Intelligent gap filling . 50g35.4.3 HQ MDCT 50g35.4.3.1 Preliminary signal analysis of past synthesis 50g35.4.3.1.1 Resampling to 8 kHz . 51g35.4.3.1.2 Pitch search by cross-correlation . 51g35.4.3.2 PLC
27、method selection . 52g35.4.3.3 MDCT frame repetition with random sign and gain scaling . 54g35.4.3.4 MDCT frame repetition with sign prediction 59g35.4.3.5 Phase ECU 60g35.4.3.5.1 Transient analysis 60g35.4.3.5.2 Spectrum analysis 62g35.4.3.5.3 Frame reconstruction . 63g35.4.3.6 MDCT concealment bas
28、ed on sinusoidal synthesis and adaptive noise filling . 64g35.4.3.6.1 FFT 64g35.4.3.6.2 Selection of sinusoidal components. 64g35.4.3.6.3 Sinusoidal synthesis . 65g35.4.3.6.4 Adaptive noise filling 65g35.4.3.6.5 Synthesis 66g35.4.3.7 Time-domain PLC and OLA . 66g35.4.3.7.1 PLC mode selection . 66g35
29、.4.3.7.2 Phase matching 70g35.4.3.7.3 Repetition and smoothing 73g35.4.4 Void 78g35.4.5 Guided concealment and recovery 78g35.4.5.1 Transmission of the synthesis class . 78g35.4.5.2 Transmission of the LTP pitch lag 78g35.4.5.3 Transmission of a voicing indicator 78g35.4.5.3a Transmission of a tonal
30、ity flag 78g35.4.5.4 ACELP to MDCT mode recovery . 78g35.4.5.5 Recovery after TCX MDCT concealment . 79g35.4.6 Handling of multiple frame losses and muting . 79g35.4.6.1 TCX MDCT 79g35.4.6.1.1 Background level tracing for rates 48, 96 and 128 kbps 79g35.4.6.1.2 TCX time domain concealment . 79g35.4.
31、6.1.3 MDCT frame repetition with sign scrambling . 80g35.4.6.1.4 Fading speed 82g35.4.6.1.5 Waveform adjustment . 82g35.4.6.2 HQ MDCT 82g35.4.6.2.1 Burst loss handling for 8 kHz audio output sampling rate . 82g35.4.6.2.2 Burst loss handling audio output sampling rates larger or equal to 16 kHz 82g35
32、.5 SID frame concealment operation 83g3ETSI ETSI TS 126 447 V14.0.0 (2017-04)53GPP TS 26.447 version 14.0.0 Release 14Annex A (informative): Change history . 84g3History 85g3ETSI ETSI TS 126 447 V14.0.0 (2017-04)63GPP TS 26.447 version 14.0.0 Release 14Foreword This Technical Specification has been
33、produced by the 3rdGeneration Partnership Project (3GPP). The contents of the present document are subject to continuing work within the TSG and may change following formal TSG approval. Should the TSG modify the contents of the present document, it will be re-released by the TSG with an identifying
34、 change of release date and an increase in version number as follows: Version x.y.z where: x the first digit: 1 presented to TSG for information; 2 presented to TSG for approval; 3 or greater indicates TSG approved document under change control. y the second digit is incremented for all changes of s
35、ubstance, i.e. technical enhancements, corrections, updates, etc. z the third digit is incremented when editorial only changes have been incorporated in the document. ETSI ETSI TS 126 447 V14.0.0 (2017-04)73GPP TS 26.447 version 14.0.0 Release 141 Scope The present document defines a frame loss conc
36、ealment procedure, also termed frame substitution and muting procedure, which is executed by the Enhanced Voice Services (EVS) decoder when one or more frames (speech or audio or SID frames) are unavailable for decoding due to e.g. packet loss, corruption of a packet or late arrival of a packet. 2 R
37、eferences The following documents contain provisions 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, subsequen
38、t revisions do not apply. - For a non-specific reference, the latest version applies. In the case of a reference to a 3GPP document (including a GSM document), a non-specific reference implicitly refers to the latest version of that document in the same Release as the present document. 1 3GPP TR 21.
39、905: “Vocabulary for 3GPP Specifications“. 2 3GPP TS 26.441: “Codec for Enhanced Voice Services (EVS); General Overview“. 3 3GPP TS 26.442: “Codec for Enhanced Voice Services (EVS); ANSI C code (fixed-point)“. 4 3GPP TS 26.444: “Codec for Enhanced Voice Services (EVS); Test Sequences“. 5 3GPP TS 26.
40、445: “Codec for Enhanced Voice Services (EVS); Detailed Algorithmic Description“. 6 3GPP TS 26.446: “Codec for Enhanced Voice Services (EVS); AMR-WB Backward Compatible Functions“. 7 R. Martin, Noise Power Spectral Density Estimation Based on Optimal Smoothing and Minimum Statistics, 2001 3 Definiti
41、ons, symbols and abbreviations 3.1 Definitions For the purposes of the present document, the terms and definitions given in TR 21.905 1 and the following apply. A term defined in the present document takes precedence over the definition of the same term, if any, in TR 21.905 1. Further EVS codec spe
42、cific definitions are found in clause 3.1 of 5. 3.2 Symbols For the purposes of the present document, the following symbols apply: EVS codec specific symbol definitions may be found in clause 3.2 of 5. ETSI ETSI TS 126 447 V14.0.0 (2017-04)83GPP TS 26.447 version 14.0.0 Release 143.3 Abbreviations F
43、or the purposes of the present document, the abbreviations given in TR 21.905 1 and the following apply. An abbreviation defined in the present document takes precedence over the definition of the same abbreviation, if any, in TR 21.905 1. AMR Adaptive Multi Rate (codec) AMR-NB Adaptive Multi Rate N
44、arrowband (codec) = AMR AMR-WB Adaptive Multi Rate Wideband (codec) EFR Enhanced Full Rate (codec) EVS Enhanced Voice Services FB Fullband FR (GSM) Full Rate (codec) HR (GSM) Half Rate (codec) JBM Jitter Buffer Management MTSI Multimedia Telephony Service for IMS NB Narrowband PLC Packet Loss Concea
45、lment PS Packet Switched PSTN Public Switched Telephone Network SWB Super Wideband WB Wideband Further EVS codec specific abbreviations may be found in clause 3.3 of 5. 4 General The purpose of the frame loss concealment procedure is to conceal the effect of any unavailable EVS frame (speech or audi
46、o or SID) for decoding. The concealment of erased frames covers both the reconstruction of missing frames and the techniques to ensure smooth and rapid recovery of normal synthesis after erased segments. The frame loss concealment procedure also covers proper strategies including muting or fading to
47、 background noise for the case of multiple frame losses in a row. The purpose of muting the output or fading to background noise in the case of several lost frames in a row is to indicate the breakdown of the channel to the user and to avoid generating possible annoying sounds as a result from the f
48、rame loss concealment procedure. Unless stated differently, fading operations (described in subclause 5.3.4 and subclause 5.4.6) start already with the first lost frame. Given the architecture and features of the EVS codec (details in EVS Codec Detailed Algorithmic Description) the frame loss concea
49、lment procedure comprises concealment methods for the various major codec modules, such as signal classification, spectral envelope (LPC), ACELP, MDCT and Bandwidth Extension. A particular feature of the EVS codec is guided frame loss concealment for which the encoder provides specific supplementary data guiding the concealment during erased frames and enhancing the convergence and recovery of the decoder after erased frames. The description in this specification is limited on how to apply the guided frame loss concealment data; the correspon
