CN105280190B - Bandwidth extension encoding and decoding method and device - Google Patents
Bandwidth extension encoding and decoding method and device Download PDFInfo
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Abstract
The invention relates to a bandwidth extension coding and decoding method and a device, which combine two key technologies of self-adaptive multi-resolution filtering, self-adaptive time-frequency grid construction and complex linear prediction coding high-frequency detail generation, can obviously improve the coding efficiency of a high-frequency part of a digital audio signal and the sound quality of the high-frequency part of the digital audio signal, and the low-frequency part of the digital audio signal can still adopt the traditional perceptual audio coding (such as DRA), thereby realizing a coding technology with higher subjective sound quality under low code rate and medium code rate. On the other hand, the invention is an enhancement tool added on the basis of high-quality perceptual coding algorithms such as DRA and the like at present, thus ensuring downward compatibility with the traditional perceptual coding algorithms such as DRA and the like. The digital audio codec realized based on the invention can be used in the fields of satellite HDTV sound processing, high-quality audio broadcasting and the like.
Description
Technical field
The present invention relates to digital audio encoding and decoding techniques, more specifically to a kind of bandwidth extension encoding and decoding side
Method and device.
Background technique
The stereo exemplary operation code rate of traditional perceptual audio technology (DRA, AAC and MP3 etc.) is 96~
128kbps, and there are apparent subjective sensations to be distorted for coding quality when 64kbps/ is stereo following.Frequency modulation broadcasting application
Typical encoder bit rate is that 48kbps~64kbps/ is stereo, and at this moment heritage has felt the subjective sound quality of audio decoding techniques
It is not able to satisfy frequency modulation broadcasting requirement.
It is proposed to this end that the bandwidth expansion (BandWidth Extension, abbreviation BWE) of digital audio and video signals encodes skill
Art.Current bandwidth extension encoding technology has very much, and performance is also irregular.It has disclosed and for the bandwidth in international standard
Extended coding technology mainly has the following two kinds encryption algorithm：
The first bandwidth extension encoding technology is frequency spectrum tape copy described in ISO/IEC 14496-3 MPEG-4
(Spectral Bandwidth Replication, abbreviation SBR) coding.Fig. 1 shows the concrete principle block diagram of SBR coding.
SBR is the algorithm of frequency domain processing, and coding principle is：Every frame signal passes through the quadrature mirror filter group of 64 subbands
(Quadrature Mirror Filter, abbreviation QMF) obtains 64 uniform sub-bands, and each sub-band includes 32 samples
Point divides a reasonable T-F-grid according to the transient response of current demand signal, and one energy information of each raster symbol-base is gone forward side by side
Row huffman coding.The algorithm includes tonality inspection and transmits an other single sinusoidal signal parameter information simultaneously.Fig. 2 shows
The decoded concrete principle block diagram of SBR is gone out.SBR decoding principle is：Pass through by the decoding pcm that core decoder (AAC) is exported
The QMF of 32 subbands obtains 32 uniform sub-bands, and each sub-band includes 32 sampling points, according to the control of SBR demultiplexing output
Parameter processed carries out high frequency generation, is then adjusted according to control parameter and envelope data to high frequency, then by 32 son of low frequency
Output with QMF and the output of adjusted rear high-frequency sub-band QMF enter 64 band QMF together and synthesize, and finally export Whole frequency band
Pcm audio signal.
The major defect of MPEG SBR coding techniques is：(1) time-frequency segmentation is relatively fixed.For 48kHz sample rate, due to
Using 64 band QMF, then maximum frequency resolution ratio is 375Hz (24khz/64)；Every 2048 sampling point of frame, then maximum time resolution ratio is about
For 1.3ms (64/48000).Since audio signal is extremely complex, this algorithm cannot meet the essence of signal analysis well sometimes
Degree requires.(2) the high frequency detail generation of SBR is directly to obtain or from low frequency part copy by simply filtering to low frequency sub-band
It obtains, in (pole) low bit- rate, this method can substantially reduce the encoder bit rate of high frequency section, but due to each sound channel
Audio signal low frequency and high frequency only have similar under very little probability, therefore the detail recovery of SBR high frequency is relatively rough, although applying
Other technologies reduce bring distortion, are still difficult to obtain higher quality in the reduction of entire high frequency section.Therefore when number
When the relatively high quality of word tone frequency coding requirement, there are obvious shortcomings for the high frequency detail processing of SBR.
Second of bandwidth extension encoding technology is a kind of simple bandwidth for including in 3GPP AMR-WB+ coding method
Expansion technique.It is a kind of algorithm of Time Domain Processing, and main code principle is：By input signal be divided into same bandwidth low frequency and
High frequency two parts time-domain signal, low frequency (LF) are partially filtered to obtain the residual signals of low frequency signal by lpc analysis, then
High frequency detail signal is simulated by high frequency LPC synthetic filtering；Then by compared with the practical high-frequency signal of practical SHF (n),
The gain vector (one yield value of every subframe) of high-frequency envelope (energy) is obtained, finally by low frequency high and low frequency tie point
The further modified gain vector of the consistency of gain, then encodes this gain vector.Therefore be transferred to decoding end includes correction
Gain vector and high frequency LPC coefficient.The high frequency decoding process of AMR-WB+ is substantially the inverse process encoded.
The bandwidth extension encoding technology of 3GPP AMR-WB+ has the following problems：(1) high-frequency coding is realized in time domain, it can not
Higher frequency resolution is obtained, because this method can consider that only one high-frequency region divides；(2) of high-frequency coding
Beginning frequency band is fixed, and can only be Fs/4, and for 48khz sample frequency, the starting frequency point of high-frequency coding is 12khz；(3) in high frequency
Harmonic signal can not accurately restore；(4) envelope restoration of high-frequency signal is not accurate enough.
In addition there are some bandwidth extension encoding technologies, time-frequency conversion unit uses traditional FFT, then will on frequency domain
High frequency is divided into several regions, encodes to the spectrum energy in each region, therefore can only to provide a temporal resolution multiple for every frame
Frequency resolution.This High Frequency Reconstruction Technology based on FFT, frequency domain resolution is high and time resolution is too low, becomes when input is fast
Audio signal when, the signal of high-frequency reconstruction cannot track the variation of original audio signal well.
Intensity-stereo encoding in digital audio encoding it is also assumed that be a kind of special bandwidth extension encoding technology,
Its principle is insensitive to the details of high frequency section using human auditory system, therefore to stereo or 5.1 surround sounds each sound channels
High frequency section carry out under mix as a sound channel, and the high frequency detail signal after normalizing as all sound channels, but each sound
The envelope (energy in high frequency critical band) of the high-frequency signal in road requires coding transmission.
Summary of the invention
The technical problem to be solved in the present invention is that in view of the above drawbacks of the prior art, providing a kind of bandwidth expansion volume
Code and coding/decoding method and device, to improve the code efficiency of digital audio and video signals high frequency section and the sound of high frequency section signal
Quality.
The technical solution adopted by the present invention to solve the technical problems is：It is proposed a kind of bandwidth extension encoding method, including
Following steps：
S1, adaptive multiresolutional filter and adaptive T-F-grid construction are carried out to the monophonic audio signal of input,
Optimal T-F-grid information is obtained, is specifically included：
S11, frequency resolution selection is carried out based on the transient state analysis to input monophonic audio signal, to input monophone
Audio channel signal carries out adaptive differentiate more and filters, and obtains optimal Time-frequency Filter signal；
S12, Transient detection and positioning are carried out to each subband signal of filtering output, the transient state according to each subband signal
Property analyze and consider the high frequency band encoder bit rate and human ear critical band characteristic of setting, carry out frequency direction and time orientation
Adaptive grid configuration obtains the best T-F-grid under current code rate；
S2, as unit of the optimal T-F-grid, carry out high frequency detail coding, specifically include：
S21, complex linear forecast analysis filtering is carried out to each subband signal for filtering output in step S11, obtained each
The residual signals of subband acquire predictive coefficient, and are sequentially completed all high-frequency sub-band residual signals and low frequency sub-band residual signals
Corresponding relationship, output subband residual error copy parameter；
S22, quantization encoding predictive coefficient；
S3, as unit of the optimal T-F-grid, each subband signal that output is filtered in step S11 is carried out high
Frequency envelope entropy coding；
S4, multiplexing and encoding parameter, output bandwidth extended coding code stream, the coding parameter include multiresolutional filter selection
Parameter, T-F-grid parameter, subband residual error copy parameter, predictive coefficient and high-frequency sub-band envelope parameters.
According to one embodiment of present invention, the step S11 further comprises：
To transient signal, thick frequency resolution and high temporal resolution is selected to be filtered；
To stable state model, thin frequency resolution and low temporal resolution is selected to be filtered；
To other audio signals, the frequency resolution of adaptively selected centre is filtered with intermediate temporal resolution
Wave.
According to one embodiment of present invention, the adaptive grid configuration of frequency direction is further in the step S12
Including：Frequency characteristic according to input monophonic audio signal higher frequency band part selects different grid configurations, specially：
To general audio signal, frequency grid gradually reduces frequency resolution with the frequency raising of highband part, so that
Frequency grid is consistent with human ear critical band；
The case where to including tone signal in highband part, under the premise of considering critical band, with the general sound
The case where frequency signal, is compared to the appropriate frequency resolution for increasing grid；
The adaptive grid configuration of time orientation further comprises in the step S12：According to input monophonic audio letter
The transient response of one or more transient signals occur in number position and each subband signal, is configured to more in time orientation
A temporal interval, each section represent a grid.
According to one embodiment of present invention, be sequentially completed in the step S21 all high-frequency sub-band residual signals with
The corresponding relationship of low frequency sub-band residual signals, output subband residual error copy parameter, further comprise：
The residual signals for analyzing each high-frequency sub-band select optimal low frequency from low frequency sub-band residual signals
Band, and the subband number of all low frequency sub-bands obtained with this is encoded and is exported.
According to one embodiment of present invention, be sequentially completed in the step S21 all high-frequency sub-band residual signals with
The corresponding relationship of low frequency sub-band residual signals, output subband residual error copy parameter, further comprise：
To continuous one group of high-frequency sub-band residual signals, selected from low frequency sub-band residual signals optimal one group it is continuously low
Frequency subband, and the starting of the multiple groups low frequency sub-band obtained with this and terminator reel number coding are exported.
According to one embodiment of present invention, the step S21 further comprises：
S211, overlapping windowing process is carried out using hamming code window to high frequency subband signals；
S212, counterweight superposition window treated high frequency subband signals carry out Linear Prediction filter, obtain high-frequency sub-band residual error
Signal；
S213, under the smallest criterion of mean square error for making residual signals, pass through Paul levinson-Du Bin algorithm solve prediction
Coefficient.
The present invention is to solve its technical problem also to propose a kind of bandwidth expansion coding/decoding method, is included the following steps：
S1, the bandwidth extension encoding code stream of input is demultiplexed, obtains coding parameter, the coding parameter includes differentiates more
Rate filters selection parameter, T-F-grid parameter, subband residual error copy parameter, predictive coefficient and high-frequency sub-band envelope parameters；
S2, entropy decoding is carried out to high-frequency sub-band envelope parameters based on T-F-grid, obtains high-frequency sub-band envelope signal；
S3, multiple orthogonal filter group analysis filtering is carried out to the low frequency signal that decoding obtains, obtains low frequency sub-band signal；
S4, it is based on T-F-grid, is carried out according to the low frequency sub-band signal and subband residual error copy parameter, predictive coefficient high
The decoding of frequency details, specifically includes：
S41, compound linear forecast analysis filtering is carried out to low frequency sub-band signal, obtains low frequency sub-band residual signals；
S42, inverse quantization decode predictive coefficient；
S43, parameter is copied according to subband residual error, low frequency sub-band residual signals is copied into high-frequency sub-band residual signals, so
The linear prediction synthetic filtering for carrying out high-frequency sub-band according to predictive coefficient afterwards, obtains high-frequency sub-band detail signal；
S5, as unit of T-F-grid, using high-frequency sub-band envelope signal adjust high-frequency sub-band detail signal, obtain high frequency
Subband signal；
S6, foundation multiresolutional filter selection parameter are carried out and are compiled to the high frequency subband signals and low frequency sub-band signal
The corresponding multiresolution synthesis in code end, exports the monophonic audio signal of Whole frequency band.
The present invention also proposes a kind of bandwidth extension encoding device to solve its technical problem, including：
Adaptive more resolution filtering and time-frequency grid configuration module, it is adaptive for being carried out to the monophonic audio signal of input
It answers multiresolutional filter and adaptive T-F-grid to construct, obtains optimal T-F-grid information, specifically include：
Adaptive differentiate filters submodule more, for carrying out frequency based on the transient state analysis to input monophonic audio signal
The selection of rate resolution ratio carries out adaptively differentiating filtering more, obtains optimal Time-frequency Filter signal to input monophonic audio signal；
T-F-grid constructs submodule, for carrying out Transient detection and positioning to each subband signal of filtering output, according to
The high frequency band encoder bit rate and human ear critical band characteristic that setting is analyzed and considered according to the transient state of each subband signal, carry out
The adaptive grid configuration of frequency direction and time orientation obtains the best T-F-grid under current code rate；
High frequency detail coding module, for carrying out high frequency detail coding, specifically as unit of the optimal T-F-grid
Including：
Compound linear forecast analysis submodule, for carrying out plural line to each subband signal for filtering output in step S11
Property forecast analysis filtering, obtain the residual signals of each subband, acquire predictive coefficient, and be sequentially completed all high-frequency sub-band residual errors letter
Corresponding relationship number with low frequency sub-band residual signals, output subband residual error copy parameter；
Quantization encoding submodule is used for quantization encoding predictive coefficient；
High-frequency envelope coding module, for being exported to filtering in step S11 as unit of the optimal T-F-grid
Each subband signal carries out high-frequency envelope entropy coding；
Parameter Multiplexing module, is used for multiplexing and encoding parameter, output bandwidth extended coding code stream, and the coding parameter includes more
Resolution ratio filters selection parameter, T-F-grid parameter, subband residual error copy parameter, predictive coefficient and high-frequency sub-band envelope parameters.
According to one embodiment of present invention, the T-F-grid construction submodule carries out the adaptive grid of frequency direction
Lattice, which is made, further comprises：Frequency characteristic according to input monophonic audio signal higher frequency band part selects different grid structures
It makes, specially：
To general audio signal, frequency grid gradually reduces frequency resolution with the frequency raising of highband part, so that
Frequency grid is consistent with human ear critical band；
The case where to including tone signal in highband part, under the premise of considering critical band, with the general sound
The case where frequency signal, is compared to the appropriate frequency resolution for increasing grid；
The adaptive grid configuration that T-F-grid construction submodule carries out time orientation further comprises：According to input
The transient response of one or more transient signals occur in monophonic audio signal position and each subband signal, in the time
For directional structure vectorical structure at multiple temporal intervals, each section represents a grid.
The present invention is to solve its technical problem also to propose a kind of bandwidth expansion decoding apparatus, which is characterized in that including：
Parameter demultiplexing module obtains coding parameter, the volume for the bandwidth extension encoding code stream demultiplexing to input
Code parameter includes multiresolutional filter selection parameter, T-F-grid parameter, subband residual error copy parameter, predictive coefficient and high frequency
Band envelope parameters；
High-frequency envelope decoder module obtains high for carrying out entropy decoding to high-frequency sub-band envelope parameters based on T-F-grid
Frequency subband envelope signal；
Multiple quadrature filtering analysis module, the low frequency signal for obtaining to decoding carry out multiple orthogonal filter group analysis filter
Wave obtains low frequency sub-band signal；
High frequency detail decoder module is copied for being based on T-F-grid according to the low frequency sub-band signal and subband residual error
Parameter, predictive coefficient carry out high frequency detail decoding, specifically include：
Compound linear forecast analysis submodule obtains low for carrying out compound linear forecast analysis filtering to low frequency sub-band signal
Frequency subband residual signals；
Inverse quantization submodule decodes predictive coefficient for inverse quantization；
High frequency synthesizes submodule, and for copying parameter according to subband residual error, low frequency sub-band residual signals are copied to high frequency
Then subband residual signals carry out the linear prediction synthetic filtering of high-frequency sub-band according to predictive coefficient, obtain high-frequency sub-band details
Signal；
High frequency adjusts module, for it is thin to adjust high-frequency sub-band using high-frequency sub-band envelope signal as unit of T-F-grid
Signal is saved, high frequency subband signals are obtained；
Adaptive multiresolution synthetic filtering module, for foundation multiresolutional filter selection parameter, to high frequency
Band signal and low frequency sub-band signal carry out multiresolution synthesis corresponding with coding side, export the monophonic audio letter of Whole frequency band
Number.
Bandwidth extension encoding and coding/decoding method of the invention and device are combined with AFAG (Adaptive multi-
Resolution Filtering&Adaptive time-frequency Griding, adaptive multiresolutional filter and adaptive
Answer time-frequency grid configuration) and CLPC (Complex Linear Predictive Coding, complex linear predictive coding) it is high
Frequency details generates two key technologies, can significantly improve the high frequency section code efficiency and high frequency section signal of digital audio and video signals
Sound quality, and traditional perceptual audio (such as DRA) still can be used in the low frequency part of digital audio and video signals, to realize
A kind of coding techniques all having higher subjective sound quality under low bit- rate and medium code rate.On the other hand, the present invention is
The enhancing tool added on the basis of the high quality such as current DRA feels encryption algorithm, also can guarantee compile with traditional feeling in this way
Code DRA scheduling algorithm is backward compatible.The digital audio codec realized based on the present invention can be used at the sound accompaniment of satellite HDTV
The fields such as reason and high quality audio broadcast.
Detailed description of the invention
Present invention will be further explained below with reference to the attached drawings and examples, in attached drawing：
Fig. 1 is the functional block diagram of existing SBR coding method；
Fig. 2 is the functional block diagram of existing SBR coding/decoding method；
Fig. 3 is the flow chart of the bandwidth extension encoding method of one embodiment of the invention；
Fig. 4 is the flow chart of the bandwidth expansion coding/decoding method of one embodiment of the invention；
Fig. 5 is the logic diagram of the bandwidth extension encoding device of one embodiment of the invention；
Fig. 6 is the logic diagram of Fig. 5 high-frequency details coding module；
Fig. 7 is the logic diagram of the bandwidth expansion decoding apparatus of one embodiment of the invention；
Fig. 8 is the logic diagram of Fig. 7 high-frequency details decoder module；
Fig. 9 is that the bandwidth extension encoding method of one embodiment of the invention is applied to the schematic diagram of DRA coding techniques；
Figure 10 is that the bandwidth expansion coding/decoding method of one embodiment of the invention is applied to the schematic diagram of DRA decoding technique；
Figure 11 is the schematic diagram of the best T-F-grid construction under constrained code rate.
Specific embodiment
In order to make the objectives, technical solutions, and advantages of the present invention clearer, with reference to the accompanying drawings and embodiments, right
The present invention is further elaborated.It should be appreciated that the specific embodiments described herein are merely illustrative of the present invention, and
It is not used in the restriction present invention.
Fig. 3 shows the flow chart of bandwidth extension encoding method 100 according to an embodiment of the invention.As shown in figure 3,
This method 100 includes the following steps：
In step S110, adaptive multiresolutional filter and adaptive time-frequency grid are carried out to the monophonic audio signal of input
Lattice is made, and optimal T-F-grid information is obtained.Specifically, step S110 further comprises following steps：
Step S111 carries out frequency resolution selection based on the transient state analysis to input monophonic audio signal, to defeated
Enter monophonic audio signal and carry out adaptive more resolution filtering, obtains optimal Time-frequency Filter signal.
In the step, the transient state of input monophonic audio signal is analyzed in real time first, then basis analyzes
Audio signal stable state/transient response carry out frequency resolution selection, to select a best multiresolutional filter device group
(QMF) audio signal is filtered, exports optimal Time-frequency Filter signal.In general, based on input monophonic sound
The selection strategy that the transient state of frequency signal carries out adaptive multiresolutional filter is as follows：
To transient signal, thick frequency resolution and high temporal resolution may be selected to be filtered；
To stable state model, thin frequency resolution and low temporal resolution may be selected to be filtered；
To other audio signals, can adaptively selected centre frequency resolution and intermediate temporal resolution filtered
Wave.
Further, it is contemplated that the influence that high-frequency signal bandwidth extended coding code rate is limited, if the total bitrate of audio-frequency signal coding
It is relatively low, so that the code rate of high-frequency band signals coding is relatively low (or the available bits of coding highband part are less), then want
The appropriate frequency resolution for reducing high-frequency band signals filtering, i.e., in the filtering for only considering input audio signal transient response and determination
Under definition case, selected frequency resolution further can be suitably reduced.
Step S112 carries out Transient detection and positioning to each subband signal of filtering output, according to each subband signal
Transient state analyze and consider the high frequency band encoder bit rate and human ear critical band characteristic of setting, carry out frequency direction and time
The adaptive grid configuration in direction obtains the best T-F-grid under current code rate.
Specific location of the construction of T-F-grid dependent on transient signal in a frame, or even believe dependent on each filtering subband
Number transient state analysis, while being also required to consider the available code rate that is distributed of highband part and human ear critical band characteristic.
Therefore the elementary tactics of adaptive T-F-grid construction mainly consists of two parts, first is that the grid configuration of time orientation, i.e., together
Sampling point combines in son in one frequency subband；First is that the grid configuration of frequency direction, i.e., combine between different frequency sub-bands.
The adaptive grid configuration strategy of frequency direction is mainly according to input monophonic audio signal higher frequency band part
Frequency characteristic selects different grid configurations, specially：To general audio signal, frequency grid with highband part frequency
Raising gradually reduces frequency resolution, so that frequency grid is consistent with human ear critical band；To in highband part include tone
The case where signal, under the premise of considering critical band, with the aforementioned general audio signal the case where compared with should suitably increase grid
Frequency resolution.The adaptive grid configuration of time orientation is mainly according to one or more winks in input monophonic audio signal
The transient response of position and each subband signal that state signal occurs, is configured to multiple temporal intervals, often in the direction of time
A section represents a grid.
In addition, the above-mentioned T-F-grid construction being calculated based on current high-frequency band signals characteristic, it will also be by high frequency
The limitation of signal bandwidth extended coding code rate, therefore also need based on high-frequency signal bandwidth extended coding code rate come to frequency direction
The grid construction obtained with time orientation is corrected, to obtain the best T-F-grid under current code rate, as shown in figure 11.
Basic correction method includes：
(1) frequency resolution of grid is reduced：I.e. in a frequency direction, the width of each grid increases, such as is originally
1/3 critical band is wide be changed to that 1/2 critical band is wide or QMF high-frequency sub-band in part low frequency sub-band using 1/3 critical band
Wide and remainder is wide using 1/2 critical band.
(2) optimize the time domain direction grid construction of different Q MF high-frequency sub-band：If the transient state based on each subband signal is special
Property carry out grid configuration, possible different Q MF subband have different grid number and each grid starting and terminate sampling point difference,
The information of transmission is more, therefore can adjust the grid configuration section of each QMF subband on the whole, shares or reduce faceted boundary
(section) description information.For example, all BWE high-frequency sub-band T-F-grids have the same grid configuration, side information is minimum；Example again
Such as, all BWE high-frequency sub-bands have n (such as：n<4) a T-F-grid, higher BWE subband have less grid number, grid number
It is the 1/2 of previous subband, and each grid is aligned with two grids of previous subband.
(3) temporal resolution of grid is reduced：I.e. in the time domain of QMF subband signal, the width for increasing grid is (i.e. each
Grid includes more subband sampling points), such as：Former time orientation constructs 16 uniform sections, can merge into 8 homogeneity ranges two-by-two
Between, or partially merge into 12 sections (the preceding strong region grid of subband signal transient state is constant, and front and rear part suitably merges).
Subsequent method 100 in the step s 120, as unit of the optimal T-F-grid, carries out high frequency detail coding.
Specifically, step S120 further comprises following steps：
Step S121 carries out complex linear forecast analysis filter to each subband signal for filtering output in above-mentioned steps S111
Wave obtains the residual signals of each subband, acquires predictive coefficient, and is sequentially completed all high-frequency sub-band residual signals and low frequency sub-band
The corresponding relationship of residual signals, output subband residual error copy parameter.Specifically, high-frequency sub-band residual signals and low frequency sub-band are residual
The relationship of difference signal can be determined by the following two kinds method：
First method：The residual signals for analyzing each high-frequency sub-band for needing parameter coding are believed from low frequency sub-band residual error
A most suitable low frequency sub-band is selected in number, and regard the subband number of this low frequency sub-band as parameter, the institute obtained in this approach
There is subband number as the copy parameter coding output of subband residual error.
Second method：To continuous one group of high-frequency sub-band residual signals, selected from low frequency sub-band residual signals optimal
One group of continuous low frequency sub-band handles institute using the starting of this group of low frequency sub-band and terminator reel number as parameter in this approach
There are high frequency subband signals, obtain multiple groups starting and terminator reel number, these subbands number are copied into parameter coding as subband residual error
Output.
Step S122, predictive coefficient that quantization encoding abovementioned steps S121 is obtained and output.
Subsequent method 100 is in step s 130, defeated to filtering in step S111 as unit of the optimal T-F-grid
Each subband signal out carries out high-frequency envelope entropy coding, exports high-frequency sub-band envelope parameters.
With all BWE coding parameters in step S140, are multiplexed, BWE code stream is exported.Wherein, coding parameter includes more
Resolution ratio filters selection parameter, T-F-grid parameter, subband residual error copy parameter, predictive coefficient and high-frequency sub-band envelope parameters.
The bandwidth extension encoding method 100 of the present embodiment passes through the adaptive grid configuration technology (abbreviation in step S110
For AFAG algorithm), best T-F-grid is obtained based on adaptive multiresolutional filter and adaptive T-F-grid construction, in favor of
The subsequent high frequency detail coded treatment of bandwidth extension encoding, can significantly improve the high frequency section code efficiency of digital audio and video signals.
The bandwidth extension encoding method 100 of the present embodiment carries out CLPC analysis and communicating predicted system to high-frequency sub-band in the step s 120
Number, guarantees the accuracy of high-frequency envelope, so as to improve the sound quality of audio signal high frequency section.
When carrying out high frequency detail coding in bandwidth extension encoding method accord to a specific embodiment of that present invention, it can pass through
Following concrete implementation process carries out CLPC analysis, acquires predictive coefficient：
The first step：Overlapping windowing process is carried out using bright (hamming) window is breathed out to high frequency subband signals.With 32 subband QMF
For, the optional a length of 96 QMF sample points of window, 64 QMF samples of 32 QMF sample points and present frame including former frame overlapping
This point, window type are hamming window.By the QMF sample point x of high-frequency sub-band khf[n] [k] obtains w after carrying out overlapping windowing processhf
[n] [k] is as follows：
whf[n] [k]=xhf[n] [k] win [n] n=0,1..., 95
Wherein, win [n] is hamming window.
Second step：Counterweight is superimposed window treated high frequency subband signals and carries out Linear Prediction filter, and it is residual to obtain high-frequency sub-band
Difference signal：
Wherein, p is prediction order, typically can choose 3 or 4；A [i] is predictive coefficient；ehf[n] [k] is that high frequency is residual
Difference sample point.
Third step：Making residual signals ehfThe mean square error of [n] [k]Under the smallest criterion, pass through
Paul levinson-Du Bin (Levinson-Durbin) algorithm solves predictive coefficient a [i].
Based on present invention bandwidth extension encoding method described above, the present invention also proposes a kind of bandwidth expansion decoding side
Method.Fig. 4 shows the flow chart of bandwidth expansion coding/decoding method 200 according to an embodiment of the invention.As shown in figure 4, the band
Wide extension coding/decoding method 200 includes the following steps：
In step S210, the BWE code stream of input is demultiplexed, coding parameter is obtained.Wherein, coding parameter includes differentiates more
Rate filters selection parameter, T-F-grid parameter, subband residual error copy parameter, predictive coefficient and high-frequency sub-band envelope parameters.
In later step S220, entropy decoding is carried out to high-frequency sub-band envelope parameters based on T-F-grid, obtains high-frequency sub-band
Envelope signal.
In later step S230, multiple orthogonal filter group (CQMF) analysis filtering is carried out to the low frequency signal that decoding obtains,
Obtain low frequency sub-band signal.I.e.：Low frequency signal is obtained by common feeling audio decoder (such as DRA decoding), to this low frequency
Signal first carries out CQMF analysis filtering, obtain in the similar low frequency sub-band signal of coding side.The low frequency sub-band signal is on the one hand
For the input of final subband synthesis, it to be on the other hand used for the generation of high-frequency sub-band detail signal.
With in step S240, it is based on T-F-grid, according to the low frequency sub-band signal and subband residual error copy parameter, pre-
It surveys coefficient and carries out high frequency detail decoding.Specifically, step S240 further comprises following steps：
Step S241 carries out compound linear prediction (CLPC) analysis filtering to low frequency sub-band signal, obtains similar to coding side
Low frequency sub-band residual signals.
In step S242, inverse quantization decodes predictive coefficient.It, can by demultiplexing BWE encoding code stream when bandwidth expansion decodes
Obtain the high frequencies details coding parameter informations such as predictive coefficient and the subband residual error copy parameter of quantization encoding.Method 200 is in step
The predictive coefficient of the quantization encoding is decoded in rapid S242 and inverse quantization, to obtain the prediction system for high frequency CLPC synthesis
Number.
In step S243, parameter is copied according to subband residual error, low frequency sub-band residual signals are copied into high-frequency sub-band residual error
Then signal carries out the linear prediction synthetic filtering of high-frequency sub-band according to predictive coefficient, obtains high-frequency sub-band detail signal.
In step s 250, as unit of T-F-grid, the high frequency obtained in applying step S220 is sub for subsequent this method 200
High-frequency sub-band detail signal obtained in band envelope signal set-up procedure S243, obtains high frequency subband signals.
In later step S260, according to multiresolutional filter selection parameter, the high-frequency sub-band obtained in step S250 is believed
Number and step S230 in the low frequency sub-band signal that obtains carry out multiresolution corresponding with coding side and synthesize, export Whole frequency band
Monophonic audio signal.
The bandwidth expansion coding/decoding method 200 of the present embodiment is replaced with low frequency residual signals most suitable in low frequency sub-band signal
High-frequency sub-band residual signals motivate the linear prediction synthetic filtering of high-frequency sub-band, can obtain preferable high frequency detail, thus
The sound quality of audio signal high frequency section can be improved.
Based on the previously described bandwidth extension encoding method of the present invention, the present invention also proposes a kind of bandwidth extension encoding dress
It sets.Fig. 5 shows the logic diagram of bandwidth extension encoding device 300 according to an embodiment of the invention.As shown in figure 5, should
Bandwidth extension encoding device 300 includes that adaptive more resolution filtering and time-frequency grid configuration (AFAG) module 310, high frequency detail are compiled
Code module 320, high-frequency envelope coding module 330 and parameter Multiplexing module 340.Wherein, AFAG module 310 is used for the list to input
Channel audio signal carries out adaptive multiresolutional filter and adaptive T-F-grid construction, obtains optimal T-F-grid letter
Breath.Specifically, AFAG module 310 further comprises that adaptive differentiate filters submodule 311 and T-F-grid construction submodule more
Block 312.Adaptive more resolution filtering submodules 311 carry out frequency based on the transient state analysis to input monophonic audio signal and divide
Resolution selection carries out adaptively differentiating filtering more, obtains optimal Time-frequency Filter signal to input monophonic audio signal.Time-frequency
Each subband signal of 312 pairs of grid configuration submodule filtering outputs carries out Transient detection and positioning, according to each subband signal
Transient state analyze and consider the high frequency band encoder bit rate and human ear critical band characteristic of setting, carry out frequency direction and time
The adaptive grid configuration in direction obtains the best T-F-grid under current code rate.High frequency detail coding module 320 is used for institute
Stating optimal T-F-grid is unit, carries out high frequency detail coding.Specifically as shown in fig. 6, high frequency detail coding module 320 into one
Step includes compound linear forecast analysis submodule 321 and quantization encoding submodule 322.Compound linear forecast analysis submodule 321 is to certainly
It adapts to each subband signals for differentiating the filtering filtering output of submodule 311 more and carries out complex linear forecast analysis filtering, obtain each
The residual signals of subband acquire predictive coefficient, and are sequentially completed all high-frequency sub-band residual signals and low frequency sub-band residual signals
Corresponding relationship, output subband residual error copy parameter to parameter Multiplexing module 340.322 quantization encoding of quantization encoding submodule is multiple
The predictive coefficient that linear prediction analysis submodule 321 acquires is exported to parameter Multiplexing module 340.High-frequency envelope coding module 330
For as unit of the optimal T-F-grid, adaptive more resolution filtering submodules 311 to be filtered with each subbands of output
Signal carries out high-frequency envelope entropy coding.Parameter Multiplexing module 340 is used for multiplexing and encoding parameter, exports BWE code stream.Wherein, it encodes
Parameter may include multiresolutional filter selection parameter, T-F-grid parameter, subband residual error copy parameter, predictive coefficient and high frequency
Band envelope parameters.Specific implementation in relation to each module in device 300, reference can be made to the aforementioned phase to bandwidth extension encoding method 100
Close description.
The bandwidth extension encoding device 300 of the present embodiment is based on adaptive multiresolutional filter and adaptive T-F-grid structure
Digital sound can be significantly improved in favor of the subsequent high frequency detail coded treatment of bandwidth extension encoding by making the best T-F-grid of acquisition
The high frequency section code efficiency of frequency signal.The bandwidth extension encoding device 300 of the present embodiment carries out CLPC analysis to high-frequency sub-band
And communicating predicted coefficient, guarantee the accuracy of high-frequency envelope, so as to improve the sound quality of audio signal high frequency section.
Based on the previously described bandwidth expansion coding/decoding method of the present invention, the present invention also proposes a kind of bandwidth expansion decoding dress
It sets.Fig. 7 shows the logic diagram of bandwidth expansion decoding apparatus 400 according to an embodiment of the invention.As shown in fig. 7, should
Bandwidth expansion jointer device 400 includes parameter demultiplexing module 410, high-frequency envelope decoder module 420, multiple quadrature filtering (CQMF)
Analysis module 430, high frequency detail decoder module 440, high frequency adjustment module 450 and adaptive multiresolution synthetic filtering module
460.Wherein, parameter demultiplexing module 410 is used to demultiplex the BWE code stream of input, obtains coding parameter.The coding parameter packet
Include multiresolutional filter selection parameter, T-F-grid parameter, subband residual error copy parameter, predictive coefficient and high-frequency sub-band envelope ginseng
Number.High-frequency envelope decoder module 420 is used to carry out entropy decoding to high-frequency sub-band envelope parameters based on T-F-grid, obtains high frequency
Band envelope signal.CQMF analysis module 430 is used to carry out the low frequency signal for example obtained by common feeling audio decoder
Multiple orthogonal filter group analysis filtering, obtains low frequency sub-band signal.High frequency detail decoder module 440 is used to be based on T-F-grid,
High frequency detail decoding is carried out according to the low frequency sub-band signal and subband residual error copy parameter, predictive coefficient, obtains high-frequency sub-band
Detail signal.High frequency adjusts module 450 and is used for as unit of T-F-grid, the height obtained using high-frequency envelope decoder module 420
Frequency subband envelope signal adjusts the high-frequency sub-band detail signal that high frequency detail decoder module 440 obtains, and generates high frequency subband signals.
Adaptive multiresolution synthetic filtering module 460 is for it is raw to adjust module 450 for high frequency according to multiresolutional filter selection parameter
At the low frequency sub-band signal that obtains of high frequency subband signals and CQMF analysis module 430 carry out more resolution corresponding with coding side
Rate synthesis, exports the monophonic audio signal of Whole frequency band.In specific embodiment, as shown in figure 8, high frequency detail decoder module 440
It further comprise compound linear forecast analysis module 441, inverse quantization module 442 and high frequency synthesis module 443.Wherein, compound linear is pre-
It surveys analysis submodule 441 and compound linear prediction (CLPC) analysis filter is carried out to the low frequency sub-band signal that CQMF analysis module 430 obtains
Wave obtains low frequency sub-band residual signals.442 pairs of the inverse quantization submodule predictive coefficients for demultiplexing obtained quantization encoding carry out inverse
Quantization decoder obtains the predictive coefficient for high frequency CLPC synthesis.High frequency synthesizes submodule 443 and executes high frequency CLPC synthesis, i.e.,
Parameter is copied according to subband residual error, low frequency sub-band residual signals are copied into high-frequency sub-band residual signals, then according to prediction system
Number carries out the linear prediction synthetic filtering of high-frequency sub-band, obtains high-frequency sub-band detail signal.Tool in relation to each module in device 400
Body is realized, reference can be made to the aforementioned associated description to bandwidth expansion coding/decoding method 200.
The bandwidth expansion decoding apparatus 400 of the present embodiment is replaced with low frequency residual signals most suitable in low frequency sub-band signal
High-frequency sub-band residual signals motivate the linear prediction synthetic filtering of high-frequency sub-band, can obtain preferable high frequency detail, thus
The sound quality of audio signal high frequency section can be improved.
The bandwidth extension encoding method that Fig. 9 shows one embodiment of the invention is applied to the schematic diagram of DRA coding techniques.
As shown in figure 9, the basic process for the DRA+ coding application example that the BWE technology is formed with DRA technology is：Input Whole frequency band audio
Signal a-road-through crosses low-pass filtering and the down-sampled low frequency part for obtaining audio signal, is then encoded by DRA；Whole frequency band simultaneously
The bandwidth extension encoding method of audio signal through the invention encodes high frequency section；Finally it is packaged into according to the frame format of DRA+
DRA+ code stream.
In DRA+ coding application example shown in Fig. 9, specific step is as follows for bandwidth extension encoding method：
The first step：The pcm audio signal of analysis input selects suitable QMF filter group according to stable state/transient response.
Complexity is taken into consideration only in DRA+, so only 32 band QMF of selection and 128 band QMF, then filtering exports 32 subbands or 128 sons
Band signal.
Second step：Pcm audio signal is further analysed in depth, transient points are detected, then carries out time orientation grid
Construction.In view of the factors such as complexity and T-F-grid side information overhead, time orientation grid is up to 8.
Third step：According to code rate and time grid configuration, carrying out the grid configuration of frequency direction, (i.e. multiple subbands are in frequency
A grid is merged into direction), so far complete final T-F-grid construction.
4th step：QMF subband carries out CLPC processing (predictive filter order is 3), and filters to the CLPC of high-frequency sub-band
Device parameter coding.
5th step：Analysis is filtered to QMF subband according to the CLPC of the 4th step, subband residual signals are obtained, for letter
Change and reduce side information, with continuous multiple subbands (subband block) for unit, analysis of high frequency subband block residual error and low frequency sub-band block are residual
The correlation of difference, selects maximally related low frequency sub-band block, using the starting subband number of low frequency sub-band block and subband block broadband as side
Information；Then it is sequentially completed the corresponding relationship of all high-frequency sub-band residual errors and low frequency sub-band residual error.
6th step：Carry out high-frequency envelope coding.
7th step：By the information in need for being transferred to decoding end be multiplexed, formed BWE code stream.
The bandwidth expansion coding/decoding method that Figure 10 shows one embodiment of the invention is applied to the signal of DRA decoding technique
Figure.As shown in Figure 10, which is with the DRA+ that DRA technology the forms basic process for decoding application example：To DRA+ code stream
It unpacks, low frequency part is decoded by DRA obtains low frequency PCM signal, this low frequency PCM signal and the high frequency BWE parameter unpacked pass through
Bandwidth expansion coding/decoding method decoding of the invention, exports as Whole frequency band PCM audio data.
In DRA+ shown in Fig. 10 decoding application example, specific step is as follows for bandwidth expansion coding/decoding method：
The first step：Demultiplexing, obtain multiresolutional filter selection parameter, T-F-grid parameter, subband residual error copy parameter,
The coding parameters information such as predictive coefficient and high-frequency sub-band envelope parameters.
Second step：To the low frequency part signal of the DRA audio signal decoded, one times of frequency lower than coding side is carried out
The QMF analysis (i.e. 16 bands or 64 bands) of resolution ratio, obtains 16 or 64 QMF low frequency sub-band filtering signals.
Third step：According to high-frequency sub-band residual error and low frequency sub-band residual error corresponding informance, height is copied to from low frequency sub-band residual error
Frequency subband residual error is restored to obtain high-frequency sub-band residual signals in this way.
4th step：CLPC filter, the high-frequency sub-band detail signal synthesized are motivated using high-frequency sub-band residual signals.
5th step：As unit of T-F-grid, with the obtained high-frequency sub-band envelope signal of decoding high-frequency sub-band envelope parameters
High-frequency sub-band detail signal is adjusted, high frequency subband signals are exported.
6th step：High frequency subband signals and low frequency sub-band signal pass through 32 band QMF corresponding with coding side or 128 band QMF
Synthetic filtering exports the monophonic audio PCM signal of Whole frequency band.
According to international test standards ITU-R BS.1534, to existing DRA, DRA+SBR and DRA+ according to the present invention
These three encoding and decoding techniques of BWE are repeatedly tested, the external testing tested and standardized including laboratory internal, test result table
It is bright：
When stereo 48kbps, DRA+BWE and DRA+SBR according to the present invention are suitable, hence it is evident that are better than DRA；
When surround sound 128kbps, DRA+BWE and DRA+SBR according to the present invention are suitable, hence it is evident that are better than DRA；
When surround sound 192kbps, DRA+BWE according to the present invention is slightly better than DRA+SBR, is all better than DRA.
Bandwidth extension encoding and coding/decoding method of the invention and device are combined with the generation of AFAG and CLPC high frequency detail
The two key technologies can significantly improve the high frequency section code efficiency of digital audio and video signals and the sound matter of high frequency section signal
Amount.Specific implementation in relation to AFAG and CLPC high frequency detail generation technique, referring also to present patent application applicant in same
Entitled " the adaptive grid configuration method and apparatus for bandwidth extension encoding " and entitled " bandwidth expansion submitted for 1
Content documented by this two pieces patent application of the method and apparatus that exhibition coding and decoding medium-high frequency generates ".
The foregoing is merely illustrative of the preferred embodiments of the present invention, is not intended to limit the invention, all in essence of the invention
Made any modifications, equivalent replacements, and improvements etc., should all be included in the protection scope of the present invention within mind and principle.
Claims (10)
1. a kind of bandwidth extension encoding method, which is characterized in that include the following steps：
S1, adaptive multiresolutional filter and adaptive T-F-grid construction are carried out to the monophonic audio signal of input, obtained
Optimal T-F-grid information, specifically includes：
S11, frequency resolution selection is carried out based on the transient state analysis to input monophonic audio signal, to input monophonic sound
Frequency signal carries out adaptive differentiate more and filters, and obtains optimal Time-frequency Filter signal；
S12, Transient detection and positioning are carried out to each subband signal of filtering output, the transient state point according to each subband signal
The high frequency band encoder bit rate and human ear critical band characteristic for analysing and considering setting, carry out the adaptive of frequency direction and time orientation
Grid configuration is answered, the best T-F-grid under current code rate is obtained；
S2, as unit of the optimal T-F-grid, carry out high frequency detail coding, specifically include：
S21, complex linear forecast analysis filtering is carried out to each subband signal for filtering output in step S11, obtains each subband
Residual signals, acquire predictive coefficient, and be sequentially completed pair of all high-frequency sub-band residual signals and low frequency sub-band residual signals
It should be related to, output subband residual error copies parameter；
S22, quantization encoding predictive coefficient；
S3, as unit of the optimal T-F-grid, to filtered in step S11 output each subband signal carry out high frequency packet
Network entropy coding；
S4, multiplexing and encoding parameter, output bandwidth extended coding code stream, the coding parameter include multiresolutional filter selection ginseng
Number, T-F-grid parameter, subband residual error copy parameter, predictive coefficient and high-frequency sub-band envelope parameters.
2. the method according to claim 1, wherein the step S11 further comprises：
To transient signal, thick frequency resolution and high temporal resolution is selected to be filtered；
To stable state model, thin frequency resolution and low temporal resolution is selected to be filtered；
To other audio signals, the frequency resolution of adaptively selected centre is filtered with intermediate temporal resolution.
3. the method according to claim 1, wherein in the step S12 frequency direction adaptive grid structure
It makes and further comprises：Frequency characteristic according to input monophonic audio signal higher frequency band part selects different grid configurations,
Specially：
To general audio signal, frequency grid gradually reduces frequency resolution with the frequency raising of highband part, so that frequency
Grid is consistent with human ear critical band；
The case where to including tone signal in highband part, believes under the premise of considering critical band with the general audio
Number the case where compared to the appropriate frequency resolution for increasing grid；
The adaptive grid configuration of time orientation further comprises in the step S12：According in input monophonic audio signal
The transient response of position and each subband signal that one or more transient signals occur, when time orientation is configured to multiple
Domain section, each section represent a grid.
4. the method according to claim 1, wherein it is residual to be sequentially completed all high-frequency sub-bands in the step S21
The corresponding relationship of difference signal and low frequency sub-band residual signals, output subband residual error copy parameter, further comprise：
The residual signals for analyzing each high-frequency sub-band select an optimal low frequency sub-band from low frequency sub-band residual signals, and
The subband number of all low frequency sub-bands obtained with this is encoded into output.
5. the method according to claim 1, wherein it is residual to be sequentially completed all high-frequency sub-bands in the step S21
The corresponding relationship of difference signal and low frequency sub-band residual signals, output subband residual error copy parameter, further comprise：
To continuous one group of high-frequency sub-band residual signals, optimal one group continuous low frequency is selected from low frequency sub-band residual signals
Band, and the starting of the multiple groups low frequency sub-band obtained with this and terminator reel number coding are exported.
6. the method according to claim 1, wherein the step S21 further comprises：
S211, overlapping windowing process is carried out using hamming code window to high frequency subband signals；
S212, counterweight superposition window treated high frequency subband signals carry out Linear Prediction filter, obtain high-frequency sub-band residual signals；
S213, under the smallest criterion of mean square error for making residual signals, pass through Paul levinson-Du Bin algorithm solve prediction system
Number.
7. a kind of bandwidth expansion coding/decoding method, which is characterized in that include the following steps：
S1, the bandwidth extension encoding code stream of input is demultiplexed, obtains coding parameter, the coding parameter includes multiresolution filter
Wave selection parameter, T-F-grid parameter, subband residual error copy parameter, predictive coefficient and high-frequency sub-band envelope parameters；
S2, entropy decoding is carried out to high-frequency sub-band envelope parameters based on T-F-grid, obtains high-frequency sub-band envelope signal；
S3, multiple orthogonal filter group analysis filtering is carried out to the low frequency signal that decoding obtains, obtains low frequency sub-band signal；
S4, it is based on T-F-grid, it is thin according to the low frequency sub-band signal and subband residual error copy parameter, predictive coefficient progress high frequency
Section decoding, specifically includes：
S41, compound linear forecast analysis filtering is carried out to low frequency sub-band signal, obtains low frequency sub-band residual signals；
S42, inverse quantization decode predictive coefficient；
S43, according to subband residual error copy parameter, low frequency sub-band residual signals are copied into high-frequency sub-band residual signals, then according to
It is predicted that coefficient carries out the linear prediction synthetic filtering of high-frequency sub-band, high-frequency sub-band detail signal is obtained；
S5, as unit of T-F-grid, using high-frequency sub-band envelope signal adjust high-frequency sub-band detail signal, obtain high-frequency sub-band
Signal；
S6, foundation multiresolutional filter selection parameter, to the high frequency subband signals and low frequency sub-band signal carries out and coding side
Corresponding multiresolution synthesis, exports the monophonic audio signal of Whole frequency band.
8. a kind of bandwidth extension encoding device, which is characterized in that including：
Adaptive more resolution filtering and time-frequency grid configuration module are adaptive more for carrying out to the monophonic audio signal of input
Resolution ratio filtering and adaptive T-F-grid construction, obtain optimal T-F-grid information, specifically include：
Adaptive differentiate filters submodule more, for carrying out frequency point based on the transient state analysis to input monophonic audio signal
Resolution selection carries out adaptively differentiating filtering more, obtains optimal Time-frequency Filter signal to input monophonic audio signal；
T-F-grid constructs submodule, for carrying out Transient detection and positioning to each subband signal of filtering output, according to every
The high frequency band encoder bit rate and human ear critical band characteristic of setting are analyzed and considered to the transient state of a subband signal, carries out frequency
The adaptive grid configuration in direction and time orientation obtains the best T-F-grid under current code rate；
High frequency detail coding module, it is specific to wrap for as unit of the optimal T-F-grid, carrying out high frequency detail coding
It includes：
Compound linear forecast analysis submodule, it is pre- for carrying out complex linear to each subband signal for filtering output in step S11
Survey analysis filtering, obtain the residual signals of each subband, acquire predictive coefficient, and be sequentially completed all high-frequency sub-band residual signals with
The corresponding relationship of low frequency sub-band residual signals, output subband residual error copy parameter；
Quantization encoding submodule is used for quantization encoding predictive coefficient；
High-frequency envelope coding module, for as unit of the optimal T-F-grid, to filtering each of output in step S11
Subband signal carries out high-frequency envelope entropy coding；
Parameter Multiplexing module, is used for multiplexing and encoding parameter, output bandwidth extended coding code stream, and the coding parameter includes differentiates more
Rate filters selection parameter, T-F-grid parameter, subband residual error copy parameter, predictive coefficient and high-frequency sub-band envelope parameters.
9. device according to claim 8, which is characterized in that the T-F-grid construction submodule carries out frequency direction
Adaptively grid configuration further comprises：Frequency characteristic according to input monophonic audio signal higher frequency band part selects different
Grid configuration, specially：
To general audio signal, frequency grid gradually reduces frequency resolution with the frequency raising of highband part, so that frequency
Grid is consistent with human ear critical band；
The case where to including tone signal in highband part, believes under the premise of considering critical band with the general audio
Number the case where compared to the appropriate frequency resolution for increasing grid；
The adaptive grid configuration that T-F-grid construction submodule carries out time orientation further comprises：According to input monophone
The transient response of one or more transient signals occur in audio channel signal position and each subband signal, in time orientation
Multiple temporal intervals are configured to, each section represents a grid.
10. a kind of bandwidth expansion decoding apparatus, which is characterized in that including：
Parameter demultiplexing module obtains coding parameter, the coding ginseng for the bandwidth extension encoding code stream demultiplexing to input
Number includes multiresolutional filter selection parameter, T-F-grid parameter, subband residual error copy parameter, predictive coefficient and high-frequency sub-band packet
Network parameter；
High-frequency envelope decoder module obtains high frequency for carrying out entropy decoding to high-frequency sub-band envelope parameters based on T-F-grid
Band envelope signal；
Multiple quadrature filtering analysis module, the low frequency signal for obtaining to decoding carry out multiple orthogonal filter group analysis filtering, obtain
Obtain low frequency sub-band signal；
High frequency detail decoder module, for be based on T-F-grid, according to the low frequency sub-band signal and subband residual error copy parameter,
Predictive coefficient carries out high frequency detail decoding, specifically includes：
Compound linear forecast analysis submodule obtains low frequency for carrying out compound linear forecast analysis filtering to low frequency sub-band signal
Band residual signals；
Inverse quantization submodule decodes predictive coefficient for inverse quantization；
High frequency synthesizes submodule, and for copying parameter according to subband residual error, low frequency sub-band residual signals are copied to high-frequency sub-band
Then residual signals carry out the linear prediction synthetic filtering of high-frequency sub-band according to predictive coefficient, obtain high-frequency sub-band detail signal；
High frequency adjusts module, for being believed as unit of T-F-grid using high-frequency sub-band envelope signal adjustment high-frequency sub-band details
Number, obtain high frequency subband signals；
Adaptive multiresolution synthetic filtering module, for believing the high-frequency sub-band according to multiresolutional filter selection parameter
Number and low frequency sub-band signal carry out corresponding with coding side multiresolution and synthesize, export the monophonic audio signal of Whole frequency band.
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| CN111210832A (en) * | 2018-11-22 | 2020-05-29 | 广州广晟数码技术有限公司 | Bandwidth extension audio coding and decoding method and device based on spectrum envelope template |
| CN111210831A (en) * | 2018-11-22 | 2020-05-29 | 广州广晟数码技术有限公司 | Bandwidth extension audio coding and decoding method and device based on spectrum stretching |
| CN109448741B (en) * | 2018-11-22 | 2021-05-11 | 广州广晟数码技术有限公司 | 3D audio coding and decoding method and device |
| CN113113032A (en) * | 2020-01-10 | 2021-07-13 | 华为技术有限公司 | Audio coding and decoding method and audio coding and decoding equipment |
| CN113593586A (en) * | 2020-04-15 | 2021-11-02 | 华为技术有限公司 | Audio signal encoding method, decoding method, encoding apparatus, and decoding apparatus |
| CN111768793B (en) * | 2020-07-11 | 2023-09-01 | 北京百瑞互联技术有限公司 | LC3 audio encoder coding optimization method, system and storage medium |
| EP4226366A2 (en) * | 2020-10-09 | 2023-08-16 | Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V. | Apparatus, method, or computer program for processing an encoded audio scene using a bandwidth extension |
| CN112669860B (en) * | 2020-12-29 | 2022-12-09 | 北京百瑞互联技术有限公司 | Method and device for increasing effective bandwidth of LC3 audio coding and decoding |
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