EP0869476B1 - Vorrichtung zur Erzeugung von Hintergrundrauschen - Google Patents

Vorrichtung zur Erzeugung von Hintergrundrauschen Download PDF

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Publication number
EP0869476B1
EP0869476B1 EP98200761A EP98200761A EP0869476B1 EP 0869476 B1 EP0869476 B1 EP 0869476B1 EP 98200761 A EP98200761 A EP 98200761A EP 98200761 A EP98200761 A EP 98200761A EP 0869476 B1 EP0869476 B1 EP 0869476B1
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EP
European Patent Office
Prior art keywords
gain
circuit
speech
noise
comfort noise
Prior art date
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Expired - Lifetime
Application number
EP98200761A
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English (en)
French (fr)
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EP0869476A1 (de
Inventor
Cyrille Morel
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Koninklijke Philips NV
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Koninklijke Philips Electronics NV
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Publication of EP0869476A1 publication Critical patent/EP0869476A1/de
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    • G—PHYSICS
    • G10—MUSICAL INSTRUMENTS; ACOUSTICS
    • G10L—SPEECH ANALYSIS TECHNIQUES OR SPEECH SYNTHESIS; SPEECH RECOGNITION; SPEECH OR VOICE PROCESSING TECHNIQUES; SPEECH OR AUDIO CODING OR DECODING
    • G10L19/00—Speech or audio signals analysis-synthesis techniques for redundancy reduction, e.g. in vocoders; Coding or decoding of speech or audio signals, using source filter models or psychoacoustic analysis
    • G10L19/012—Comfort noise or silence coding

Definitions

  • the present invention relates to a comfort noise generation device for a speech decoder receiving speech signals which correspond to an original sequence formed by successive frames of predetermined length and have been previously coded in a speech coder comprising in particular a circuit for determining the energy of the current frame and a circuit of determination of the envelope of this frame by so-called LPC analysis.
  • a voice activity detector that identifies, in input signals where voice signals are mixed with noise and moments of silence, the periods when speech signals are present.
  • the following speech coder transmits regularly (all frames) a stream of data digital that will allow a remote contact to reconstitute these speech signals later.
  • we no longer detects speech we no longer send coded frames on the network, in order to save speed on it.
  • This solution is effective for flow reduction, but can lead to unpleasant effects for the interlocutor. Indeed, in most cases there is no silence total in the places where the conversation takes place, but rather ambient noise. If so, at the time of speech / silence transitions, samples of input signals are forced to zero, the contact will have the impression of a discontinuity in the conversation, or even a line break.
  • the object of the invention is to propose a comfort noise generating device remedying this drawback.
  • the invention relates to a comfort noise generating device such as defined in the introductory paragraph of the description and which is further characterized in that it includes in series, to allow generation of a comfort noise frame in the absence of speech signals in said current frame, a Gaussian noise generation circuit, a subset two gain definition channels in parallel and an adder of the outputs of said lanes on the exit of which is available said comfort noise frame generated in the absence of speech signals, the first way to define gain comprising in series a gain circuit, the gain is directly related to the calculated energy for each current frame, a coefficient filter determined by said LPC analysis, and a multiplier by a weighting coefficient ⁇ , and the second gain definition channel including a multiplier by the additional weighting coefficient (1- ⁇ ).
  • This device makes it possible to restore to the remote contact a better quality of message. Indeed, by transmitting during the beaches of silence some frames that contain the essential characteristics of ambient noise, remove this unpleasant cut feeling line in the event of total silence.
  • the coding of these some noise frames is very inexpensive in debit, since there is only to send the frequency and energy characteristics of the noise signal, which are sufficient to restore, for the caller, a noticeable noise equivalent.
  • Noise generation devices comfort are already provided in speech coders described for example in US-A-5537509, in C.B.
  • the solution implemented does not depend on the coder.
  • dictionaries from waveforms which were traditionally present in speech coders but at addition to the filtered noise of a Gaussian noise, which is particularly interesting when noise ambient is very weak.
  • the input signals are available in the form of successive frames TR n-1 , TR n , ... etc ... of predetermined duration.
  • This coding part firstly comprises, as indicated in the figure, a circuit 11 for determining the energy of the current frame, also called gain analysis, as well as a circuit 12 for determining the envelope of this frame (from the frequency point of view) by means of an analysis known as LPC (in English: l inear p redictive c oding) which makes it possible to estimate coefficients of linear prediction.
  • LPC in English: l inear p redictive c oding
  • the comfort noise generation device firstly comprises a circuit 21 of generation of a Gaussian noise.
  • This circuit is not a dictionary of waveforms and therefore does require no memory.
  • the calculation allowing this generation is a real-time sum of numbers pseudo-random (we get a Gaussian signal if the number of iterations is large enough, minus about ten generally sufficient).
  • This noise is sent in parallel on two ways of defining gain 30 and 40, the first of which includes a series gain circuit 31 (this gain is determined by the energy - which has been transmitted - of the current frame concerned), a filter 32 (including the LPC coefficients - also transmitted- have been estimated as indicated above) and a multiplier 33.
  • the output of this multiplier 33 and that of a similar multiplier 43 constituting the other channel 40 constitute the inputs of a adder 25 at the output of which is present the TBC comfort noise frame reconstructed in the absence of speech signals.
  • the present invention is not not limited to this embodiment, from from which variants may be provided.
  • decoding we can take into account the that we reduced the bit rate by not transmitting not each time a coded frame: to decrease the abrupt transitions it is then possible to do an interpolation with the previous frames, in this which concerns energy and filter coefficients.

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  • Engineering & Computer Science (AREA)
  • Computational Linguistics (AREA)
  • Signal Processing (AREA)
  • Health & Medical Sciences (AREA)
  • Audiology, Speech & Language Pathology (AREA)
  • Human Computer Interaction (AREA)
  • Physics & Mathematics (AREA)
  • Acoustics & Sound (AREA)
  • Multimedia (AREA)
  • Compression, Expansion, Code Conversion, And Decoders (AREA)
  • Transmission Systems Not Characterized By The Medium Used For Transmission (AREA)

Claims (1)

  1. Vorrichtung zur Erzeugung von Komfortrauschen für einen Sprachdekodierer, der Sprachsignale erhält, die einer aus aufeinanderfolgenden Rastern gebildeten Originalsequenz vorbestimmter Länge entsprechen, die zuvor in einem Sprachkodierer kodiert wurden, der insbesondere eine Schaltung zur Bestimmung der Energie (11) des laufenden Rasters und eine Schaltung zur Bestimmung der Umhüllung (12) dieses Rasters per so genannter LPC-Analyse beinhaltet, dadurch gekennzeichnet, dass sie zur möglichen Erzeugung eines Komfortrauschrasters bei ausbleibenden Sprachsignalen in dem besagten laufenden Raster in Serie eine Schaltung zur Erzeugung eines gaußschen Rauschens (21), ein Untersystem aus zwei Stimmen (30, 40) zur parallelen Leistungsdefinition und einen Addierer der Ausgänge der besagten Wege enthält, an dessen Ausgang das besagte Komfortrauschraster verfügbar ist, das bei ausbleibenden Sprachsignalen erzeugt wird, wobei der erste Leistungsdefinitionsweg in Serie eine Leistungsschaltung (31), deren Leistung in direktem Verhältnis mit der Energie steht, die für jedes laufende Raster berechnet wird, einen von der besagten LPC-Analyse definierten Koeffizientenfilter (32) und einen Multiplizierer (33) mit einem Wägungskoeffizienten enthält, und der zweite Leistungsdefinitionsweg einen Multiplizierer (43) mit dem zusätzlichen Wägungskoeffizienten (L- α) enthält.
EP98200761A 1997-03-25 1998-03-10 Vorrichtung zur Erzeugung von Hintergrundrauschen Expired - Lifetime EP0869476B1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR9703617 1997-03-25
FR9703617A FR2761512A1 (fr) 1997-03-25 1997-03-25 Dispositif de generation de bruit de confort et codeur de parole incluant un tel dispositif

Publications (2)

Publication Number Publication Date
EP0869476A1 EP0869476A1 (de) 1998-10-07
EP0869476B1 true EP0869476B1 (de) 2004-11-17

Family

ID=9505153

Family Applications (1)

Application Number Title Priority Date Filing Date
EP98200761A Expired - Lifetime EP0869476B1 (de) 1997-03-25 1998-03-10 Vorrichtung zur Erzeugung von Hintergrundrauschen

Country Status (6)

Country Link
US (1) US6108623A (de)
EP (1) EP0869476B1 (de)
JP (1) JPH10340097A (de)
CN (1) CN1132327C (de)
DE (1) DE69827545T2 (de)
FR (1) FR2761512A1 (de)

Families Citing this family (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6240383B1 (en) * 1997-07-25 2001-05-29 Nec Corporation Celp speech coding and decoding system for creating comfort noise dependent on the spectral envelope of the speech signal
US6621834B1 (en) * 1999-11-05 2003-09-16 Raindance Communications, Inc. System and method for voice transmission over network protocols
GB2356538A (en) 1999-11-22 2001-05-23 Mitel Corp Comfort noise generation for open discontinuous transmission systems
US20030120484A1 (en) * 2001-06-12 2003-06-26 David Wong Method and system for generating colored comfort noise in the absence of silence insertion description packets
US20030093270A1 (en) * 2001-11-13 2003-05-15 Domer Steven M. Comfort noise including recorded noise
US7243065B2 (en) * 2003-04-08 2007-07-10 Freescale Semiconductor, Inc Low-complexity comfort noise generator
US9236063B2 (en) 2010-07-30 2016-01-12 Qualcomm Incorporated Systems, methods, apparatus, and computer-readable media for dynamic bit allocation
US9208792B2 (en) * 2010-08-17 2015-12-08 Qualcomm Incorporated Systems, methods, apparatus, and computer-readable media for noise injection
US8589153B2 (en) 2011-06-28 2013-11-19 Microsoft Corporation Adaptive conference comfort noise
CN108053830B (zh) * 2012-08-29 2021-12-07 日本电信电话株式会社 解码方法、解码装置、和计算机可读取的记录介质
CN104978970B (zh) 2014-04-08 2019-02-12 华为技术有限公司 一种噪声信号的处理和生成方法、编解码器和编解码系统
GB2532041B (en) 2014-11-06 2019-05-29 Imagination Tech Ltd Comfort noise generation
CN109841222B (zh) * 2017-11-29 2022-07-01 腾讯科技（深圳）有限公司 音频通信方法、通信设备及存储介质

Family Cites Families (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS63124636A (ja) * 1986-11-14 1988-05-28 Kokusai Denshin Denwa Co Ltd <Kdd> 音声伝送システムの疑似信号挿入方式
CA2021514C (en) * 1989-09-01 1998-12-15 Yair Shoham Constrained-stochastic-excitation coding
US5537509A (en) * 1990-12-06 1996-07-16 Hughes Electronics Comfort noise generation for digital communication systems
US5327457A (en) * 1991-09-13 1994-07-05 Motorola, Inc. Operation indicative background noise in a digital receiver
US5828997A (en) * 1995-06-07 1998-10-27 Sensimetrics Corporation Content analyzer mixing inverse-direction-probability-weighted noise to input signal
US5689615A (en) * 1996-01-22 1997-11-18 Rockwell International Corporation Usage of voice activity detection for efficient coding of speech
US5864799A (en) * 1996-08-08 1999-01-26 Motorola Inc. Apparatus and method for generating noise in a digital receiver

Also Published As

Publication number Publication date
FR2761512A1 (fr) 1998-10-02
US6108623A (en) 2000-08-22
JPH10340097A (ja) 1998-12-22
DE69827545D1 (de) 2004-12-23
EP0869476A1 (de) 1998-10-07
DE69827545T2 (de) 2005-12-15
CN1194507A (zh) 1998-09-30
CN1132327C (zh) 2003-12-24

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