ETSI TS 126 447-2018 Universal Mobile Telecommunications System (UMTS) LTE Codec for Enhanced Voice Services (EVS) Error concealment of lost packets (V15 0 0 3GPP TS 26 447 version.pdf

1、 ETSI TS 126 447 V15.0.0 (2018-07) Universal Mobile Telecommunications System (UMTS); LTE; Codec for Enhanced Voice Services (EVS); Error concealment of lost packets (3GPP TS 26.447 version 15.0.0 Release 15) TECHNICAL SPECIFICATION ETSI ETSI TS 126 447 V15.0.0 (2018-07)13GPP TS 26.447 version 15.0.

2、0 Release 15Reference RTS/TSGS-0426447vf00 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、3GPP TS 26.447 version 15.0.0 Release 15Intellectual Property Rights Essential patents IPRs essential or potentially essential to normative deliverables may have been declared to ETSI. The information pertaining to these essential IPRs, if any, is publicly available for ETSI members and non-members,

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13、ention of those trademarks in the present document does not constitute an endorsement by ETSI of products, services or organizations associated with those trademarks. Foreword This Technical Specification (TS) has been produced by ETSI 3rd Generation Partnership Project (3GPP). The present document

14、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. The cross reference between GSM, UMTS, 3GPP and ETSI identities can be found under http:/webapp.ets

15、i.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 as described in clause 3.2 of the ETSI Drafting Rules (Verbal forms for the expression of provisions)

16、. “must“ and “must not“ are NOT allowed in ETSI deliverables except when used in direct citation. ETSI ETSI TS 126 447 V15.0.0 (2018-07)33GPP TS 26.447 version 15.0.0 Release 15Contents Intellectual Property Rights 2g3Foreword . 2g3Modal verbs terminology 2g3Foreword . 5g31 Scope 6g32 References 6g3

17、3 Definitions, symbols and abbreviations . 6g33.1 Definitions 6g33.2 Symbols 6g33.3 Abbreviations . 6g34 General . 7g35 Detailed description 7g35.1 Concealment operation related to signal classification. 7g35.1.1 Overview 7g35.1.2 Signal class estimation 8g35.2 Concealment operation related to spect

18、ral envelope (LPC) representation 10g35.2.1 Specifics to rates 9.6, 16.4 and 24.4kbps 12g35.2.2 Specifics to AMR-WB IO mode . 12g35.2.3 Check for Mid LSF stability . 12g35.2.4 Adaptive interpolation of LSFs . 13g35.2.5 LPC gain compensation 14g35.3 Concealment operation related to ACELP modes 15g35.

19、3.1 General 15g35.3.1.1 Extrapolation of future pitch . 15g35.3.1.2 Construction of the periodic part of the excitation 17g35.3.1.2.1 Particularity of rate 5.9, 7.2, 8.0 and 13.2 kbps . 18g35.3.1.3 Glottal pulse resynchronization . 18g35.3.1.3.1 Condition to perform resynchronisation 18g35.3.1.3.2 P

20、erforming glottal pulse resynchronization . 18g35.3.1.4 Construction of the random part of the excitation . 20g35.3.1.5 Spectral envelope concealment, synthesis and updates . 21g35.3.1.5.1 Specifics for rates 9.6, 16.4 and 24.4 kbps 21g35.3.1.6 GSC mode concealment 21g35.3.1.7 Specifics for AMR-WB I

21、O modes 21g35.3.1.8 Reconstructed excitation . 23g35.3.1.8.1 Particularity of rate 5.9, 7.2, 8.0 and 13.2 kbps . 23g35.3.2 Concealment for bandwidth extension for ACELP modes . 23g35.3.2.1 Time domain bandwidth extension . 23g35.3.2.1.1 SWB time domain bandwidth extension . 23g35.3.2.1.1.1 The recon

22、struction of the global frame gain 24g35.3.2.1.1.2 The reconstruction of the gain attenuation factor . 25g35.3.2.1.1.3 Specifics for rates 13.2 and 32 kbps 26g35.3.3 Guided concealment and recovery 28g35.3.3.1 Specifics for rate 24.4 kbps . 28g35.3.3.2 Specifics for rates 9.6, 16.4 and 24.4 kbps 28g

23、35.3.3.3 Energy control during recovery. 29g35.3.3.4 Specifics for rates 32 and 64 kbps . 32g35.3.3.4.1 Adaptive codebook resynchronization and fast recovery (WB) 32g35.3.3.4.1.1 Decoding glottal pulse position 32g35.3.3.4.1.2 Performing glottal pulse resynchronization . 32g35.3.3.4.2 Artificial ons

24、et reconstruction . 33g35.3.4 Handling of multiple frame losses and muting . 34g35.3.4.1 Specifics for rates 5.9, 6.8, 8.0, 13.2, 32 and 64 kbps . 34g35.3.4.2 Specifics for rates 9.6, 16.4 and 24.4 kbps 34g35.3.4.2.1 Fading to background level . 34g3ETSI ETSI TS 126 447 V15.0.0 (2018-07)43GPP TS 26.

25、447 version 15.0.0 Release 155.3.4.2.2 Fading to background spectral shape . 35g35.3.4.2.3 Fading speed 36g35.4 Concealment operation related to MDCT modes . 37g35.4.1 PLC method selection . 37g35.4.2 TCX MDCT 37g35.4.2.1 PLC method selection . 37g35.4.2.2 TCX time domain concealment. 38g35.4.2.2.1

26、Construction of the periodic part of the excitation 38g35.4.2.2.2 Construction of the random part of the excitation . 39g35.4.2.2.3 Construction of the total excitation, synthesis and updates . 40g35.4.2.3 MDCT frame repetition with sign scrambling 40g35.4.2.4 Tonal MDCT concealment using phase pred

27、iction . 41g35.4.2.4.1 Overview . 41g35.4.2.4.2 Peak detection of tonal components 41g35.4.2.4.3 Phase prediction. 44g35.4.2.5 Non-tonal concealment with waveform adjustment 44g35.4.2.5.1 Preliminary concealment in frequency domain . 44g35.4.2.5.2 Waveform adjustment in time domain 45g35.4.2.6 Intel

28、ligent gap filling . 48g35.4.3 HQ MDCT 49g35.4.3.1 Preliminary signal analysis of past synthesis 49g35.4.3.1.1 Resampling to 8 kHz . 49g35.4.3.1.2 Pitch search by cross-correlation . 49g35.4.3.2 PLC method selection . 50g35.4.3.3 MDCT frame repetition with random sign and gain scaling . 52g35.4.3.4

29、MDCT frame repetition with sign prediction 57g35.4.3.5 Phase ECU 58g35.4.3.5.1 Transient analysis 58g35.4.3.5.2 Spectrum analysis 60g35.4.3.5.3 Frame reconstruction . 61g35.4.3.6 MDCT concealment based on sinusoidal synthesis and adaptive noise filling . 62g35.4.3.6.1 FFT 62g35.4.3.6.2 Selection of

30、sinusoidal components. 62g35.4.3.6.3 Sinusoidal synthesis . 63g35.4.3.6.4 Adaptive noise filling 63g35.4.3.6.5 Synthesis 64g35.4.3.7 Time-domain PLC and OLA . 64g35.4.3.7.1 PLC mode selection . 64g35.4.3.7.2 Phase matching 68g35.4.3.7.3 Repetition and smoothing 71g35.4.4 Void 75g35.4.5 Guided concea

31、lment and recovery 75g35.4.5.1 Transmission of the synthesis class . 75g35.4.5.2 Transmission of the LTP pitch lag 76g35.4.5.3 Transmission of a voicing indicator 76g35.4.5.3a Transmission of a tonality flag 76g35.4.5.4 ACELP to MDCT mode recovery . 76g35.4.5.5 Recovery after TCX MDCT concealment .

32、76g35.4.6 Handling of multiple frame losses and muting . 76g35.4.6.1 TCX MDCT 76g35.4.6.1.1 Background level tracing for rates 48, 96 and 128 kbps 76g35.4.6.1.2 TCX time domain concealment . 77g35.4.6.1.3 MDCT frame repetition with sign scrambling . 77g35.4.6.1.4 Fading speed 79g35.4.6.1.5 Waveform

33、adjustment . 80g35.4.6.2 HQ MDCT 80g35.4.6.2.1 Burst loss handling for 8 kHz audio output sampling rate . 80g35.4.6.2.2 Burst loss handling audio output sampling rates larger or equal to 16 kHz 80g35.5 SID frame concealment operation 81g3Annex A (informative): Change history . 82g3History 83 ETSI ET

34、SI TS 126 447 V15.0.0 (2018-07)53GPP TS 26.447 version 15.0.0 Release 15Foreword This Technical Specification has been 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 appr

35、oval. Should the TSG modify the contents of the present document, it will be re-released by the TSG with an identifying 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

36、or greater indicates TSG approved document under change control. y the second digit is incremented for all changes of substance, 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 1

37、26 447 V15.0.0 (2018-07)63GPP TS 26.447 version 15.0.0 Release 151 Scope The present document defines a frame loss concealment 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 SI

38、D frames) are unavailable for decoding due to e.g. packet loss, corruption of a packet or late arrival of a packet. 2 References The following documents contain provisions which, through reference in this text, constitute provisions of the present document. - References are either specific (identifi

39、ed by date of publication, edition number, version number, etc.) or non-specific. - For a specific reference, subsequent 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 refere

40、nce implicitly refers to the latest version of that document in the same Release as the present document. 1 3GPP TR 21.905: “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);

41、 ANSI C code (fixed-point)“. 4 3GPP TS 26.444: “Codec for Enhanced Voice Services (EVS); Test Sequences“. 5 3GPP TS 26.445: “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“.

42、7 R. Martin, Noise Power Spectral Density Estimation Based on Optimal Smoothing and Minimum Statistics, 2001 3 Definitions, 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 th

43、e present document takes precedence over the definition of the same term, if any, in TR 21.905 1. Further EVS codec specific 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

44、 in clause 3.2 of 5. 3.3 Abbreviations For 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 R

45、ate (codec) AMR-NB Adaptive Multi Rate Narrowband (codec) = AMR AMR-WB Adaptive Multi Rate Wideband (codec) ETSI ETSI TS 126 447 V15.0.0 (2018-07)73GPP TS 26.447 version 15.0.0 Release 15EFR Enhanced Full Rate (codec) EVS Enhanced Voice Services FB Fullband FR (GSM) Full Rate (codec) HR (GSM) Half R

46、ate (codec) JBM Jitter Buffer Management MTSI Multimedia Telephony Service for IMS NB Narrowband PLC Packet Loss Concealment 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 Th

47、e purpose of the frame loss concealment procedure is to conceal the effect of any unavailable EVS frame (speech or audio 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

48、after erased segments. The frame loss concealment procedure also covers proper strategies including muting or fading to 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 in

49、dicate the breakdown of the channel to the user and to avoid generating possible annoying sounds as a result from the frame 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 concealment procedure comprises concealment methods for the various major codec modules, such as signal classification, spectral envelope (L