WO2000045378A2 - Codage efficient de l'enveloppe spectrale mettant en oeuvre une resolution temps frequence et une commutation temps frequence - Google Patents

Codage efficient de l'enveloppe spectrale mettant en oeuvre une resolution temps frequence et une commutation temps frequence Download PDF

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Publication number
WO2000045378A2
WO2000045378A2 PCT/SE2000/000158 SE0000158W WO0045378A2 WO 2000045378 A2 WO2000045378 A2 WO 2000045378A2 SE 0000158 W SE0000158 W SE 0000158W WO 0045378 A2 WO0045378 A2 WO 0045378A2
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WO
WIPO (PCT)
Prior art keywords
time
frequency
resolution
signal
spectral envelope
Prior art date
Application number
PCT/SE2000/000158
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English (en)
Other versions
WO2000045378A3 (fr
Inventor
Lars Gustaf Liljeryd
Kristofer KJÖRLING
Per Ekstrand
Fredrik Henn
Original Assignee
Lars Gustaf Liljeryd
Kjoerling Kristofer
Per Ekstrand
Fredrik Henn
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from SE9900256A external-priority patent/SE9900256D0/xx
Application filed by Lars Gustaf Liljeryd, Kjoerling Kristofer, Per Ekstrand, Fredrik Henn filed Critical Lars Gustaf Liljeryd
Priority to AU25856/00A priority Critical patent/AU2585600A/en
Priority to US09/763,128 priority patent/US6978236B1/en
Publication of WO2000045378A2 publication Critical patent/WO2000045378A2/fr
Priority to AU78212/00A priority patent/AU7821200A/en
Priority to RU2002111665/09A priority patent/RU2236046C2/ru
Priority to EP00968271A priority patent/EP1216474B1/fr
Priority to CNB008136025A priority patent/CN1172293C/zh
Priority to DE60012198T priority patent/DE60012198T2/de
Priority to AT00968271T priority patent/ATE271250T1/de
Priority to JP2001528974A priority patent/JP4035631B2/ja
Priority to ES00968271T priority patent/ES2223591T3/es
Priority to PCT/SE2000/001887 priority patent/WO2001026095A1/fr
Priority to BRPI0014642A priority patent/BRPI0014642B1/pt
Priority to DK00968271T priority patent/DK1216474T3/da
Priority to PT00968271T priority patent/PT1216474E/pt
Publication of WO2000045378A3 publication Critical patent/WO2000045378A3/fr
Priority to HK03101398.3A priority patent/HK1049401B/zh
Priority to JP2005292384A priority patent/JP4628921B2/ja
Priority to JP2005292388A priority patent/JP4334526B2/ja
Priority to US11/246,283 priority patent/US7181389B2/en
Priority to US11/246,284 priority patent/US7191121B2/en

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Classifications

    • 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
    • G10L19/04—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 using predictive techniques
    • G10L19/06—Determination or coding of the spectral characteristics, e.g. of the short-term prediction coefficients
    • 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
    • G10L25/00—Speech or voice analysis techniques not restricted to a single one of groups G10L15/00 - G10L21/00
    • G10L25/03—Speech or voice analysis techniques not restricted to a single one of groups G10L15/00 - G10L21/00 characterised by the type of extracted parameters
    • G10L25/18—Speech or voice analysis techniques not restricted to a single one of groups G10L15/00 - G10L21/00 characterised by the type of extracted parameters the extracted parameters being spectral information of each sub-band

Definitions

  • the present invention relates to a new method and apparatus for efficient coding of spectral envelopes in audio coding systems
  • the method may be used both for natural audio coding and speech coding and is especially suited for coders usmg SBR [WO 98/57436] and other high frequency reconstruction methods
  • Audio source codmg techniques can be divided into two classes natural audio codmg and speech codmg Natural audio codmg is commonly used for music or arbitrary signals at medium bitrates, and generally offers wide audio bandwidth Speech coders are basically limited to speech reproduction but can on the other hand be used at very low bitrates, albeit with low audio bandwidth In both classes, the signal is generally separated into two major signal components, the "spectral envelope” and the corresponding "residual" signal Throughout the following description, the term “spectral envelope” refers to the coarse spectral distribution of the signal in a general sense, e g filter coefficients m an linear prediction based coder or a set of time-frequency averages of subband samples in a subband coder The term “residual” refers to the fine spectral distribution in a general sense, e g the LPC error signal or subband samples normalized usmg the above time-frequency averages "Envelope data” refers to the quantized and coded spectral envelope, and "resi
  • the spectral envelope is a function of two variables time and frequency
  • the encodmg can be done by exploiting redundancy m either direction of the time/frequency plane
  • codmg of the spectral envelope is performed in the frequency direction usmg delta coding (DPCM), linear prediction (LPC), or vector quantization (VQ) SUMMARY OF THE INVENTION
  • DPCM frequency direction usmg delta coding
  • LPC linear prediction
  • VQ vector quantization
  • the present mvention provides a new method and an apparatus for spectral envelope encoding
  • the mvention teaches how to perform and signal compactly a time/frequency mapping of the envelope representation, and further, encode the spectral envelope data efficiently using adaptive time/frequency direction codmg
  • a time/frequency grid with low temporal and high frequency resolution is used as default
  • the temporal resolution is increased at the expense of frequency resolution
  • the mvention describes two schemes for signalling of the time and frequency resolution used One scheme allows arbitrary selection of instantaneous resolution by explicit signalling of time segment borders and frequency resolutions, whereas the other exploits the fact that transients are separated at least by a minimum time, T mm , ⁇ order to reduce the required number of control bits
  • a transient detector decides whether the current granule contains a transient, and if so, determines the position of the onset of the transient The position withm the granule is encode
  • the present mvention presents a new and efficient method for scalefactor redundancy codmg
  • a dirac pulse in the time domain transforms to a constant in the frequency domain, and a drrac in the frequency domain, l e a single smusoid, corresponds to a signal with constant magnitude m the time domain Simplified, on a short term basis, the signal shows less variations in one domam than the other
  • usmg prediction or delta codmg, codmg efficiency is mcreased if the spectral envelope is coded in either time- or frequency-direction depending on the signal characte ⁇ stics
  • Figs la - lb illustrate uniform respective non-uniform sampling in time of the spectral envelope
  • Figs 2a - 2c illustrate transient detector look-ahead and granule mterdependency
  • Figs 3a - 3f illustrate segments with different time and frequency resolutions, and the corresponding control signals Fig 4 illustrates time/frequency switched envelope codmg
  • Fig 5 is a block diagram of an encoder using the envelope coding according to the mvention
  • Fig 6 is a block diagram of a decoder usmg the envelope codmg according to the invention DESCRIPTION OF PREFERRED EMBODIMENTS
  • Fig 1 shows the time/frequency representation of a musical signal where sustained chords are combmed with sharp transients with mainly high frequency contents
  • the chords have high energy and the transient energy is low, whereas the opposite is true
  • m the highband
  • the envelope data that is generated durmg time intervals where transients are present is dominated by the high intermittent transient energy
  • the decoder the spectral envelope of the transposed signal is estimated using the same mstantaneous t ⁇ me-/frequency resolution as used for the analysis of the original highband
  • An equalization of the transposed signal is then performed, based on dissimilarities m the spectral envelopes E g amplification factors in an envelope adjustmg filterbank are calculated as the quotients between o ⁇ gmal signal and transposed signal scalefactors
  • the transposed signal has the same chord to transient energy ratio as the lowband
  • the gams needed in order to adjust the transposed transients to the correct level thus cause the
  • the prmcipal solution is to maintam a low update rate durmg tonal passages, which make up the majority of a typical programme material, and by means of a transient detector localize the transient positions, and update the envelope data close to the leading flanks, see Fig lb
  • the update rate is momentarily increased in a time interval after the transient start This eliminates gain induced post-echoes
  • the time segmenting during the decay is not as crucial as findmg the start of the transient, as will be explained later
  • a lower frequency resolution can be used durmg the transient, keeping the data size within limits
  • a non-uniform samplmg in time and frequency as outlined above is applicable both on subband coders and linear prediction based coders
  • Typical coders operate on a block basis, where every block represents a fixed time interval Those blocks will be referred to as "granules"
  • granules Let a granule have a length of q time quantization steps, hereinafter called “subgranules"
  • subgranules a transient detector look-ahead can be employed on the encoder side Having this additional information, envelope data spanning across borders of granules can be comprised This enables a more flexible selection of time/frequency resolutions, and faciliates constant bitrate operation, smce parts of the payload can be moved between consecutive granules Referring to Fig 2, the granules are divided into eight subgranules
  • the transient detector operates on granules with the same timespan as the granule that overlap 50% of two consecutive granules, that is, the transient detector look-ahead is half a granule
  • the transient detector has detected a transient
  • the segment borders and frequency resolutions (number of coefficients or scalefactors) must be signalled If a non-uniform sampling according to Fig 2 is to be employed, the problem of envelope data spanning over the granule borders must be dealt with Furthermore, the signalling must be flexible enough to cover all combinations of interest, without generating a too large amount of control data
  • transients can occur withm a granule m C combinations, ranging from no transient at all to q transients, where C is given by
  • the first step towards an efficient signalling is to employ two time sampling modes, uniform and non-uniform sampling in time
  • the uniform mode is used during quasi-stationary passages, and employs high frequency resolution and relatively long time segments, both of which are predefined Hence this mode does not require any signalling of segment borders or frequency resolutions
  • One bit is sufficient to signal the time samplmg mode to the decoder
  • the non-uniform mode is used durmg transient passages and requires additional signalling Two such signalling systems are proposed by the present invention
  • the first system hereinafter referred to as the "border-signalling system" uses one bit per subgranule to signal whether a segment border is present at the subgranule left border or not Envelope data corresponding to a segment is always sent m the granule in which the segment starts This means that the number of envelopes transmitted m a granule equals the number of left borders in the granule or the bit sum of the q border bits
  • the segment frequency resolutions are signalled with dynamically allocated control bits, e g one bit per envelope Again, this number of bits is derived from the q border bits
  • Fig 3 Some examples of grouping of subgranules into time segments are given m Fig 3, where the subgranules are numbered from 000 to 111 L denotes low frequency resolution and H denotes high resolution
  • L denotes low frequency resolution
  • H denotes high resolution
  • the number of scalefactors or coefficients m a high resolution segment is assumed to be two times that of a low resolution segment
  • Figure 3a shows a reference system, constantly using the highest possible time and frequency resolution
  • the relative data matrix size is one by definition, and obviously no control signal bits are needed in this system If no transient is present in or next to a specific granule, the granule is divided mto two segments of equal length and the envelope representations are calculated using high frequency resolution If the two envelope representations do not differ more than a certain amount, only one set of high resolution envelope data is sent Those cases are illustrated by Figs 3b and 3c, where the control signal "Uniform" tells that uniform sampling in time is used, and the signal “Low
  • the second system heremafter referred to as the "position-signalling system" is intended for very low bitrate applications and utilizes some musical signal properties m order to reduce the number of control signal bits
  • the positions-signalling system are intended for very low bitrate applications and utilizes some musical signal properties m order to reduce the number of control signal bits
  • Eq 1 many of the states described by Eq 1 are not very likely, and would also generate too large amounts of envelope data to be practical at a limited bitrate
  • the following simplifications can be made with little or no sacrifice of quality for practical signals
  • the minimum time-span between consecutive transients in music programme material can be estimated in the following way In musical notation, the rhythmic "pulse" is described by a time signature expressed as a fraction A/B, where A denotes the number of "beats" per bar and MB is the type of note corresponding to one beat, for example a l A note, commonly referred to as a quarter note
  • A denotes the number of "beats” per bar
  • MB is the type of note corresponding to one beat, for example a l A note, commonly referred to as a quarter note
  • BPM Beats Per Mmute
  • T q The necessary time resolution T q must also be established In some cases a transient original signal has its mam energy in the highband to be reconstructed This means that the encoded spectral envelope must carry all the "timing" information The desired timing precision thus determines the resolution needed for encodmg of leading flanks T q is much smaller than the minimum note period T nm ⁇ n , smce small time deviations within the period clearly can be heard In most cases however, the transient has significant energy in the lowband
  • T m the gain- induced pre-echoes must fall within the so called pre- or backward masking time T m of the human auditory system m order to be inaudible Hence T q must satisfy two conditions
  • T m ⁇ T Formula mm (otherwise the notes would be so fast that they could not be resolved) and according to ["Modeling the Additivity of Nonsimultaneous Masking", Hearmg Res , vol 80, pp 105-118 (1994)], T m amounts to 10-20 ms Smce T classroom mm is in the 50ms range, a reasonable selection of T q according to Eq 3 results m that the second condition is also met
  • the precision of the transient detection in the encoder and the time resolution of the analysis/synthesis filterbank must also be considered when selecting T q
  • the note-off position has little or no effect on the perceived rhythm
  • most instruments do not exhibit sharp trailing flanks, but rather a smooth decay curve, l e a well defined note-off time does not exist
  • the post- or forward masking time is substantially longer than the pre-masking time
  • Time/Frequency Switched Scalefactor Encoding Utilizing a time to frequency transform it can be shown that a pulse in the time domain corresponds to a flat spectrum m the frequency domain, and a "pulse" in the frequency domain, l e a single sinusoidal, corresponds to a quasi-stationary signal in the time domain In other words a signal usually shows more transient properties m one domain than the other In a spectrogram, l e a time/frequency matrix display, this property is evident, and can advantageously be used when codmg spectral envelopes
  • a tonal stationary signal can have a very sparse spectrum not suitable for delta codmg m the frequency-direction, but well suited for delta codmg in the time-direction, and vice versa This is displayed in Fig 4 Throughout the following description a vector of scale factors calculated at time n 0 represents the spectral envelope
  • Y(k,n 0 ) [a ⁇ , a 2 , a 3 , , a k , ,a N ], (Eq 5) where ⁇ a N are the amplitude values for different frequencies Common practice is to code the difference between adjacent values in the frequency-direction at a given time, which yields
  • Start values are transmitted whenever the spectral envelope is coded m the frequency direction but not when coded in the time direction smce they are available at the decoder, through the previous envelope
  • the proposed algorithm also require extra information to be transmitted, namely a time/frequency flag indicating in which direction the spectral envelope was coded
  • the T/F algorithm can advantageously be used with several different coding schemes of the scalefactor-envelope representation apart from DPCM and Huffman, such as ADPCM, LPC and vector quantisation
  • the proposed T/F algorithm gives significant bitrate-reduction for the spectral-envelope data, up to around 20% reduction compared to commonly used delta-coding techniques If the number of scalefactors per octave is constant, it is possible to delta code on an octave basis instead of delta codmg of adjacent scale factors
  • the analogue input signal is fed to an A/D- converter 501, forming a digital signal
  • the digital audio signal is fed to a perceptual audio encoder 502, where source codmg is performed
  • the digital signal is fed to a transient detector 503 and to an analysis filterbank 504, which splits the signal mto its spectral equivalents (subband signals)
  • the transient detector could operate on the subband signals from the analysis bank, but for generality purposes it is here assumed to operate on the digital time domam samples directly
  • the transient detector divides the signal mto granules and determines, accordmg to the invention, whether subgranules withm the granules is to be flagged as transient
  • This information is sent to the envelope groupmg block 505, which specifies the time/frequency grid to be used for the current granule Accordmg to the grid, the block combmes the uniform sampled subband signals, to form the non-uniform
  • the decoder side of the invention is shown in Fig 6
  • the demultiplexer 601 restores the signals and feeds the approp ⁇ ate part to an audio decoder 602, which produces a low band digital audio signal
  • the envelope information is fed from the demultiplexer to the envelope decodmg block 603, which, by use of control data, determines in which direction the current envelope are coded and decodes the data
  • the low band signal from the audio decoder is routed to the transposition module 604, which generates a replicated high band signal consisting of one or several harmomcs from the low band signal.
  • the high band signal is fed to an analysis filterbank 606, which is of the same type as on the encoder side.
  • the subband signals are combined m the scalefactor grouping umt 607.
  • the same type of combination and time/frequency distribution of the subband samples is adopted as on the encoder side.
  • the envelope information from the demultiplexer and the information from the scalefactor groupmg umt is processed m the gam control module 608.
  • the module computes gam factors to be applied to the subband samples before recombmation in the synthesis filterbank block 609.
  • the output from the synthesis filterbank is thus an envelope adjusted high band audio signal This signal is added to the output from the delay unit 605, which is fed with the low band audio signal.
  • the delay compensates for the processmg time of the high band signal
  • the obtamed digital wideband signal is converted to an analogue audio signal m the digital to analogue converter 610

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Spectroscopy & Molecular Physics (AREA)
  • Computational Linguistics (AREA)
  • Signal Processing (AREA)
  • Health & Medical Sciences (AREA)
  • Audiology, Speech & Language Pathology (AREA)
  • Human Computer Interaction (AREA)
  • Acoustics & Sound (AREA)
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  • Compression, Expansion, Code Conversion, And Decoders (AREA)

Abstract

La présente invention concerne un nouveau procédé et un appareil de codage de l'enveloppe spectrale. L'invention se rapporte à une manière d'effectuer et d'indiquer de façon compacte un mappage temps fréquence de la représentation de l'enveloppe, ainsi qu'à une manière de coder efficacement les données de l'enveloppe spectrale au moyen d'un codage directionnel temps fréquence adaptatif. Ce procédé est applicable tant pour le système de codage audio naturel que pour le système de codage de la parole, et convient particulièrement pour des codeurs mettant en oeuvre une méthode SBR [WO 98/57436] ou une autre méthode de reconstruction haute fréquence.
PCT/SE2000/000158 1999-01-27 2000-01-26 Codage efficient de l'enveloppe spectrale mettant en oeuvre une resolution temps frequence et une commutation temps frequence WO2000045378A2 (fr)

Priority Applications (19)

Application Number Priority Date Filing Date Title
AU25856/00A AU2585600A (en) 1999-01-27 2000-01-26 Efficient spectral envelope coding using variable time/frequency resolution and time/frequency switching
US09/763,128 US6978236B1 (en) 1999-10-01 2000-01-26 Efficient spectral envelope coding using variable time/frequency resolution and time/frequency switching
DK00968271T DK1216474T3 (da) 1999-10-01 2000-09-29 Effektiv spektral indhyllingskurvekodning ved anvendelse af variabel tids/frekvensoplösning
PT00968271T PT1216474E (pt) 1999-10-01 2000-09-29 Codificacao eficiente de envolvente especial utilizando resolucao tempo/frequencia variavel
AT00968271T ATE271250T1 (de) 1999-10-01 2000-09-29 Kodierung der hüllkurve des spektrums mittels variabler zeit/frequenz-auflösung
BRPI0014642A BRPI0014642B1 (pt) 1999-10-01 2000-09-29 codificação de envelope espectral usando resolução de tempo-frequência variável e mudança de tempo-frequência
EP00968271A EP1216474B1 (fr) 1999-10-01 2000-09-29 Codage efficace de l'enveloppe spectrale par resolution temps/frequence variable
CNB008136025A CN1172293C (zh) 1999-10-01 2000-09-29 有效频谱包络编码方法及其编解码设备
DE60012198T DE60012198T2 (de) 1999-10-01 2000-09-29 Kodierung der hüllkurve des spektrums mittels variabler zeit/frequenz-auflösung
AU78212/00A AU7821200A (en) 1999-10-01 2000-09-29 Efficient spectral envelope coding using variable time/frequency resolution and time/frequency switching
JP2001528974A JP4035631B2 (ja) 1999-10-01 2000-09-29 可変時間／周波数分解能および時間／周波数切り替えを使用する効率的なスペクトルエンベロープ符号化
ES00968271T ES2223591T3 (es) 1999-10-01 2000-09-29 Codificacion eficaz de envolvente especial utilizando una resolucion tiempo/frecuencia variable.
PCT/SE2000/001887 WO2001026095A1 (fr) 1999-10-01 2000-09-29 Codage efficace de l'enveloppe spectrale par resolution temps/frequence et commutation temps/frequence variables
RU2002111665/09A RU2236046C2 (ru) 1999-10-01 2000-09-29 Эффективное кодирование огибающей спектра с использованием переменного разрешения по времени и по частоте и переключения время/частота
HK03101398.3A HK1049401B (zh) 1999-10-01 2003-02-24 有效頻譜包絡編碼方法及其編解碼設備
JP2005292388A JP4334526B2 (ja) 1999-10-01 2005-10-05 可変時間／周波数分解能および時間／周波数切り替えを使用する効率的なスペクトルエンベロープ符号化
JP2005292384A JP4628921B2 (ja) 1999-10-01 2005-10-05 可変時間／周波数分解能および時間／周波数切り替えを使用する効率的なスペクトルエンベロープ符号化
US11/246,283 US7181389B2 (en) 1999-10-01 2005-10-11 Efficient spectral envelope coding using variable time/frequency resolution and time/frequency switching
US11/246,284 US7191121B2 (en) 1999-10-01 2005-10-11 Efficient spectral envelope coding using variable time/frequency resolution and time/frequency switching

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
SE9900256A SE9900256D0 (sv) 1999-01-27 1999-01-27 Metod och anordning för förbättring av effektivitet och ljudkvalitet hos ljudkodare
SE9900256-0 1999-01-27
SE9903552-9 1999-10-01
SE9903552A SE9903552D0 (sv) 1999-01-27 1999-10-01 Efficient spectral envelope coding using dynamic scalefactor grouping and time/frequency switching

Related Child Applications (3)

Application Number Title Priority Date Filing Date
US09763128 A-371-Of-International 2000-01-26
US11/246,284 Division US7191121B2 (en) 1999-10-01 2005-10-11 Efficient spectral envelope coding using variable time/frequency resolution and time/frequency switching
US11/246,283 Division US7181389B2 (en) 1999-10-01 2005-10-11 Efficient spectral envelope coding using variable time/frequency resolution and time/frequency switching

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WO2000045378A2 true WO2000045378A2 (fr) 2000-08-03
WO2000045378A3 WO2000045378A3 (fr) 2000-11-16

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AU (1) AU2585600A (fr)
SE (1) SE9903552D0 (fr)
WO (1) WO2000045378A2 (fr)

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WO2002093560A1 (fr) * 2001-05-10 2002-11-21 Dolby Laboratories Licensing Corporation Ameliorations apportees a la performance transitoire de systemes de codage audio a faible debit binaire par reduction du pre-bruit
US7246065B2 (en) 2002-01-30 2007-07-17 Matsushita Electric Industrial Co., Ltd. Band-division encoder utilizing a plurality of encoding units
US7283954B2 (en) 2001-04-13 2007-10-16 Dolby Laboratories Licensing Corporation Comparing audio using characterizations based on auditory events
EP1603117A3 (fr) * 2001-07-10 2008-02-06 Coding Technologies Sweden AB Codage stéréo paramétrique efficace et échelonnable pour applications à faible débit
US7461002B2 (en) 2001-04-13 2008-12-02 Dolby Laboratories Licensing Corporation Method for time aligning audio signals using characterizations based on auditory events
US7508947B2 (en) 2004-08-03 2009-03-24 Dolby Laboratories Licensing Corporation Method for combining audio signals using auditory scene analysis
US7610205B2 (en) 2002-02-12 2009-10-27 Dolby Laboratories Licensing Corporation High quality time-scaling and pitch-scaling of audio signals
WO2010003543A1 (fr) * 2008-07-11 2010-01-14 Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V. Appareil et procédé de calcul de données d'extension de bande passante utilisant un découpage en trames contrôlant la balance spectrale
US7711123B2 (en) 2001-04-13 2010-05-04 Dolby Laboratories Licensing Corporation Segmenting audio signals into auditory events
US8041578B2 (en) 2006-10-18 2011-10-18 Fraunhofer-Gesellschaft Zur Foerderung Der Angewandten Forschung E.V. Encoding an information signal
US8126721B2 (en) 2006-10-18 2012-02-28 Fraunhofer-Gesellschaft Zur Foerderung Der Angewandten Forschung E.V. Encoding an information signal
US8170882B2 (en) 2004-03-01 2012-05-01 Dolby Laboratories Licensing Corporation Multichannel audio coding
US8280743B2 (en) 2005-06-03 2012-10-02 Dolby Laboratories Licensing Corporation Channel reconfiguration with side information
US8417532B2 (en) 2006-10-18 2013-04-09 Fraunhofer-Gesellschaft Zur Foerderung Der Angewandten Forschung E.V. Encoding an information signal
US8605911B2 (en) 2001-07-10 2013-12-10 Dolby International Ab Efficient and scalable parametric stereo coding for low bitrate audio coding applications
WO2014118179A1 (fr) * 2013-01-29 2014-08-07 Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V. Codeurs audio, décodeurs audio, systèmes, procédés et programmes d'ordinateur utilisant une résolution temporelle accrue à proximité temporelle de débuts ou de fins de fricatives ou d'affriquées
US9043200B2 (en) 2005-04-13 2015-05-26 Fraunhofer-Gesellschaft Zur Foerderung Der Angewandten Forschung E.V. Adaptive grouping of parameters for enhanced coding efficiency
US9761237B2 (en) 2001-11-29 2017-09-12 Dolby International Ab High frequency regeneration of an audio signal with synthetic sinusoid addition
RU2650031C2 (ru) * 2013-08-29 2018-04-06 Долби Интернэшнл Аб Проектирование таблицы частотных диапазонов для алгоритмов высокочастотной реконструкции
US10157623B2 (en) 2002-09-18 2018-12-18 Dolby International Ab Method for reduction of aliasing introduced by spectral envelope adjustment in real-valued filterbanks

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