CN107786184A - Audible spectrum conversion process method - Google Patents
Audible spectrum conversion process method Download PDFInfo
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- CN107786184A CN107786184A CN201610778488.XA CN201610778488A CN107786184A CN 107786184 A CN107786184 A CN 107786184A CN 201610778488 A CN201610778488 A CN 201610778488A CN 107786184 A CN107786184 A CN 107786184A
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
- H03H17/00—Networks using digital techniques
- H03H17/02—Frequency selective networks
- H03H17/0211—Frequency selective networks using specific transformation algorithms, e.g. WALSH functions, Fermat transforms, Mersenne transforms, polynomial transforms, Hilbert transforms
- H03H17/0213—Frequency domain filters using Fourier transforms
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
- H03H17/00—Networks using digital techniques
- H03H17/02—Frequency selective networks
- H03H2017/0298—DSP implementation
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Abstract
The present invention relates to a kind of audible spectrum conversion process method, comprise the following steps：Input signal obtains HFS and low frequency part in signal through Lin Kuizi Rayleigh wave filters, harmonic signal is generated using the low frequency signal of gained, abbreviation is carried out to the harmonic signal of generation using Taylor series, obtain DC component corresponding to the harmonic signal, fundametal compoment and higher hamonic wave group, due to fundametal compoment, it is known that the system directly filters out fundametal compoment, and the harmonic signal obtained by use subtracts fundametal compoment, corresponding DC component is obtained, and is filtered out.The method amount of calculation of its generation higher hamonic wave being mainly characterized by the invention is small, digital hardware realizes difficulty is small, resource consumption is few, need not calculate current demand signal in real time various higher harmonic components, also without the fundametal compoment filtered out using sef-adapting filter in current harmonic signal, it make use of missing fundamental principle, tonequality is improved well, compensate for the deficiency of loudspeaker LF-response ability.
Description
Technical field
The present invention relates to field of audio processing, more particularly to the field of audio processing of tone quality improving, in particular to a kind of height
The audible spectrum conversion process method of effect.
Background technology
Field of audio processing utilizes missing fundamental principle, and the low frequency part of audio signal is converted into height by special algorithm
Subharmonic is combined to simulate low-frequency sound, compensate for the deficiency of loudspeaker LF-response ability, therefore this method can improve tonequality.
Low frequency signal in audio signal is filtered out and is converted to corresponding higher hamonic wave and combined by existing design, no matter existing technology
It is to use the virtual bass (Virtual Bass) of frequency domain processing mode and the MaxxBass technologies using Time Domain Processing mode, it is past
It is past the problems such as complicated, computationally intensive to be all present, and be often all based on realizing on DSP, but pass through numeral in the chips
Then cost is too high for logic realization.
Described virtual bass (Virtual Bass) employs frequency domain processing mode, and its implementation is generally：Input
Signal x (n) first passes around frequency divider, filters out high and low frequency signal respectively, then carries out down-sampled processing to low frequency signal, afterwards
FFT (Fast Fourier Transform (FFT)) processing is carried out, time-domain signal is transformed into frequency domain and handled, points of three frequency ranges (40~50Hz,
50~75Hz, 75~150Hz) respectively construct low frequency higher hamonic wave.Then carried out using the harmonic amplitude and phase constructed
IFFT (Fourier inversion), obtains time-domain signal, finally carries out a liter sampling processing processing, is specifically shown in Fig. 2.
Described MaxxBass algorithms generate the harmonic signal of unlimited order using multiplication loop, and utilize fading gain g
The influence of Eliminate highter harmonic.High-pass filter OUT-HPF and FB-HPF are used for reducing DC influence and reduce the intermodulation of system
Distortion.Here OUT-HPF uses 4 rank elliptical high pass filters, cut-off frequency f2=150Hz, FB-HPF are irrigated using 2 rank Barts
Think high-pass filter, cut-off frequency f1=40Hz.Upwards Compressor Logic modules are by generating control signal C
(n) harmonic amplitude control is realized, to ensure dynamic equilibrium of the loudness to sound pressure level at each harmonic, is specifically shown in Fig. 3.
Above method calculating is sufficiently complex, and causes larger system delay, in order to reduce the meter in whole process
Complexity is calculated, realizes the real-time conversion without using DSP, in order to reduce system delay larger when DSP is handled, reduction is designed to
This, proposes a kind of audible spectrum conversion solution of low-cost high-efficiency.
Linkwitz-Riley wave filters can be formed by two second order Butterworth wave filters cascades, by changing level
The parameter of two second order Butterworth wave filters of connection is rung to change the frequency of corresponding Linkwitz-Riley wave filters
Should, so as to realize that the method for the frequency dividing of different frequency belongs to known content.
The content of the invention
The shortcomings that the invention aims to overcome prior art, there is provided a kind of low frequency part using input signal is given birth to
Into higher harmonic components, the method for the efficient audible spectrum conversion for reducing system delay, reduction amount of calculation and design cost.
To achieve the above object, audible spectrum conversion process method of the invention is as follows：Based on frequency divider, harmonic generation mould
Block, fundametal compoment filter out module, and DC component filters out module harmonic gain module, and the input connection of described frequency divider is defeated
Enter signal, the output end of the frequency divider is connected respectively to the defeated of the input harmonic gain module of described harmonic generation module
Enter end, the fundametal compoment that the output end connection of described harmonic generation module is described filters out the fast input of mould, described fundamental wave
The DC component that component is filtered out described in the output end connection of module filters out the input of module, and described DC component filters out module
The described harmonics module of output end connection input, it is characterised in that described method comprises the following steps：
(1) input signal is divided by described allocator module, and obtains the HFS h of the input signal
And low frequency part g (t) (t)；
(2) described low frequency part g (t) is produced by harmonic wave y (t) by described harmonic generation module, passes through harmonic wave y
(t) deformation obtains described DC component, fundametal compoment and higher harmonic components group, wherein, harmonic wave produces according to below equation：
(3) module is filtered out by described fundametal compoment and filters out fundametal compoment；
(4) module is filtered out by described DC component and filters out the DC component included in described harmonic wave y (t)；
(5) described higher harmonic components group is amplified by described harmonics module；
(6) by the high-frequency signal h (t) of generation in described step (1) higher harmonic components groups added after amplification and defeated
Go out.
It is preferred that described allocator module is connected with a high-pass filter and a low pass filter respectively, it is described
Step (1) is specially：
Described allocator module is by described high-pass filter and low pass filter, from the high-pass filter and low pass
The output end of wave filter obtains described high-frequency signal h (t) and low frequency signal g (t) respectively.
Obtained it is preferred that the amplitude const2 of described fundametal compoment is deformed by described harmonic wave y (t).
It is preferred that filtering out fundametal compoment in described step (3), it is specially：
Described fundametal compoment filters out module and filters out fundametal compoment according to below equation, obtains z (t)：
Z (t)=y (t)-const2*g (t)；
Wherein, const2 is the amplitude of fundametal compoment, and const2*g (t) is fundametal compoment, and z (t) is described harmonic wave y
(t) remainder after fundametal compoment is filtered out, is made up of described DC component and higher harmonic components group.
It is preferred that the DC component in described step (4) filters out, it is specially：
The block isolating device in module is filtered out by described DC component and filters out described DC component.
It is preferred that the amplification higher harmonic components group in described step (5), is specially：
Pass through the described higher harmonic components group of the power amplifier amplification in described harmonics module.
It is preferred that described allocator module is Linkwitz-Riley wave filters.
More preferably, described Linkwitz-Riley wave filters are by two second order Butterworth wave filter structures cascaded
Into.
Most preferably, described Linkwitz-Riley wave filters are by changing described second order Butterworth wave filters
Coefficient change its frequency response to realize its corresponding scaling down processing.
Employ the present invention audible spectrum conversion process method, due to its without using DSP (Digital Signal Processing) i.e.
Can in real time change, calculate simple, thus greatly reduce the computation complexity in whole process, when will not produce DSP processing compared with
Big system delay, and design cost is cheap, less internal memory is taken than prior art, computation complexity is lower, be it is a kind of it is low into
This efficient audible spectrum conversion solution.
Brief description of the drawings
Fig. 1 is that the algorithm of virtual bass (Virtual Bass) technology in the prior art realizes block diagram.
Fig. 2 is that the algorithm of MaxxBass technologies in the prior art realizes block diagram.
Fig. 3 is the step schematic flow sheet of the audible spectrum conversion process method of the present invention.
Embodiment
In order to more clearly describe the technology contents of the present invention, further retouched with reference to embodiment
State.
The audible spectrum conversion process method of the present invention,
Module is filtered out based on frequency divider, harmonic generation module, fundametal compoment, DC component filters out module harmonic gain mould
Block, the input connection input signal of described frequency divider, the output end of the frequency divider are connected respectively to described harmonic generation
The input of the input harmonic gain module of module, the fundamental wave that the output end connection of described harmonic generation module is described divide
Amount filters out the fast input of mould, and the DC component that described fundametal compoment filters out described in the output end connection of module filters out module
Input, described DC component filter out the input of the harmonics module described in the output end connection of module, and its feature exists
In described method comprises the following steps：
(1) input signal is divided by described allocator module, and one connected by described frequency divider
High-pass filter and a low pass filter obtain the HFS h (t) and low frequency part g (t) of the input signal；
(2) described low frequency part g (t) is produced by harmonic wave y (t) by described harmonic generation module, passes through harmonic wave y
(t) deformation obtains described DC component, fundametal compoment and higher harmonic components group, wherein, harmonic wave produces according to below equation：
(3) module is filtered out by described fundametal compoment and filters out fundametal compoment, filter out fundametal compoment with specific reference to following public affairs
Formula is carried out, and obtains z (t)：
Z (t)=y (t)-const2*g (t)；
Wherein, const2 is the amplitude of fundametal compoment, and const2*g (t) is fundametal compoment, and z (t) is described harmonic wave y
(t) remainder after described fundametal compoment is filtered out, and is made up of described DC component and higher harmonic components group, and
The amplitude const2 of fundametal compoment can be deformed by described harmonic wave y (t) and obtained.；
(4) block isolating device that module is filtered out by described DC component filters out the direct current included in described harmonic wave y (t) point
Amount；
(5) described higher harmonic components group is amplified by the power amplifier in described harmonics module；
(6) by the high-frequency signal h (t) of generation in described step (1) higher harmonic components groups added after amplification and defeated
Go out.
In a kind of preferably embodiment, described allocator module is Linkwitz-Riley wave filters.
In a kind of more preferably embodiment, described Linkwitz-Riley wave filters are by two second orders cascaded
Butterworth wave filters are formed.
In a kind of most preferably embodiment, described Linkwitz-Riley wave filters are by changing described second order
The coefficient number of Butterworth wave filters changes its frequency response to realize its corresponding scaling down processing.
In actual applications, a kind of specific implementation process of the invention refers to Fig. 3.
Input signal passes through a Linkwitz-Riley wave filters first, i.e., described frequency divider on ordinary meaning
(Crossover), the high frequency in signal is separated with low frequency part.Then produced using obtained low frequency signal corresponding
Higher hamonic wave group.
Described Linkwitz-Riley wave filters are two second order Butterworth wave filters cascades.In the design
This module do not had into a fixed coefficient, system can change whole filtering by adjusting the coefficients of second order Butterworth wave filters
The frequency response of device, so as to realize the frequency dividing for different frequency.
By numerous studies and experiment, the harmonic generation of signal is realized using a relatively simple formula in the design
Purpose, its derivation are as follows：
Assuming that input audio signal is tonal signal：
G (t)=sin (2 π f) ... (1)
Then have, harmonic signal is：
According to Taylor series, the polynomial equation of the approximation of sinusoidal sin (x) is as follows：
It is possible thereby to which formula 2 is further derived, push type 3 is as follows：
In the calculating iteration 4 times of 16bit digital display circuits Chinese style 3, that is, calculate to n=3, finally used in this algorithm
Formula is：
G (t)=sin (x), which is brought into, can draw following result in formula 4：
So can be in the hope of y (t) DC component and fundametal compoment sin (x) coefficient：
A problem is occurred as soon as herein：Assuming that sin (x) is 0, can be drawn in substitution formula 4Input and be
When zero, export and beDC waveform, and the DC component formula 6 by being calculated includes sin2(x)、sin4
And sin (x)6(x) DC component when deploying.It follows that above formula regards all input signal sin (x) as an angle value,
And the DC component present in actual signal (null value or other steady state values) cannot be distinguished by above formula.Therefore,
(6) value wouldn't can use, and (7) value can be used directly.
The fundametal compoment size of harmonic generation module residual is assured that using formula, so as to directly be eliminated, such as
Shown in following formula：
Z (t)=y (t)-const2*g (t) ... (8)
So z (t) directly eliminates fundametal compoment, and DC component is then directly filtered by DC Blocking (block isolating device)
Remove.
The audible spectrum conversion process method of the present invention is employed, because it can be changed without using DSP in real time, is calculated
Simply, thus the computation complexity in whole process is greatly reduced, system delay larger during DSP processing will not be produced, and
Design cost is cheap, and less internal memory is taken than prior art, and computation complexity is lower, is a kind of audio frequency of low-cost high-efficiency
Compose conversion solution.
In this description, the present invention is described with reference to its specific embodiment.But it is clear that it can still make
Various modifications and alterations are without departing from the spirit and scope of the present invention.Therefore, specification and drawings are considered as illustrative
It is and nonrestrictive.
Claims (9)
1. a kind of audible spectrum conversion process method, module, direct current are filtered out based on frequency divider, harmonic generation module, fundametal compoment
Component filters out module harmonic gain module, the input connection input signal of described frequency divider, the output end of the frequency divider
It is connected respectively to the input of the input harmonic gain module of described harmonic generation module, described harmonic generation module
The described fundametal compoment of output end connection filter out the input of module, described fundametal compoment filters out the output end connection of module
Described DC component filters out the input of module, and the harmonic wave that described DC component filters out described in the output end connection of module increases
The input of beneficial module, it is characterised in that described method comprises the following steps：
(1) input signal is divided by described allocator module, and obtains the HFS h (t) of the input signal
With low frequency part g (t)；
(2) described low frequency part g (t) is produced by harmonic wave y (t) by described harmonic generation module, become by harmonic wave y (t)
Shape obtains described DC component, fundametal compoment and higher harmonic components group, wherein, harmonic wave produces according to below equation：
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(3) module is filtered out by described fundametal compoment and filters out fundametal compoment；
(4) module is filtered out by described DC component and filters out the DC component included in described harmonic wave y (t)；
(5) described higher harmonic components group is amplified by described harmonics module；
(6) by the high-frequency signal h (t) of generation in described step (1) the higher harmonic components groups added after amplification and export.
2. audible spectrum conversion process method according to claim 1, it is characterised in that described allocator module difference
It is connected with a high-pass filter and a low pass filter, described step (1) is specially：
Described allocator module is by described high-pass filter and low pass filter, from the high-pass filter and LPF
The output end of device obtains described high-frequency signal h (t) and low frequency signal g (t) respectively.
3. audible spectrum conversion process method according to claim 1, it is characterised in that the amplitude of described fundametal compoment
Const2 is deformed by described harmonic wave y (t) and obtained.
4. audible spectrum conversion process method according to claim 1, it is characterised in that the filter in described step (3)
Except fundametal compoment, it is specially：
Described fundametal compoment filters out module and filters out fundametal compoment according to below equation, obtains z (t)：
Z (t)=y (t)-const2*g (t)；
Wherein, const2 is the amplitude of fundametal compoment, and const2*g (t) is fundametal compoment, and z (t) is that described harmonic wave y (t) is filtered
Formed except the remainder after fundametal compoment, and by described DC component and higher harmonic components group.
5. audible spectrum conversion process method according to claim 1, it is characterised in that straight in described step (4)
Flow component filters out, and is specially：
The block isolating device in module is filtered out by described DC component and filters out described DC component.
6. audible spectrum conversion process method according to claim 1, it is characterised in that putting in described step (5)
Big higher harmonic components group, it is specially：
Pass through the described higher harmonic components group of the power amplifier amplification in described harmonics module.
7. audible spectrum conversion process method according to claim 1, it is characterised in that described allocator module is
Linkwitz-Riley wave filters.
8. audible spectrum conversion process method according to claim 7, it is characterised in that described Linkwitz-Riley
Wave filter is made up of the second order Butterworth wave filters of two cascades.
9. audible spectrum conversion process method according to claim 8, it is characterised in that described Linkwitz-Riley
Wave filter changes its frequency response to realize that its is corresponding by changing the coefficient of described second order Butterworth wave filters
Scaling down processing.
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110957995A (en) * | 2019-10-25 | 2020-04-03 | 四川汇源光通信有限公司 | Distributed fault monitoring device IIR filtering system and design method thereof |
| CN113452158A (en) * | 2021-05-28 | 2021-09-28 | 北京理工大学 | Environmental electromagnetic wave energy acquisition system |
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| US20070253576A1 (en) * | 2006-04-27 | 2007-11-01 | National Chiao Tung University | Method for virtual bass synthesis |
| CN102547517A (en) * | 2011-12-30 | 2012-07-04 | Tcl集团股份有限公司 | Bass signal harmonic generating method and device and sound playing equipment |
| CN102957988A (en) * | 2011-08-24 | 2013-03-06 | 半导体元件工业有限责任公司 | Audio signal processing circuit |
| CN103297898A (en) * | 2013-06-24 | 2013-09-11 | 深圳Tcl新技术有限公司 | Low frequency extending method and device |
-
2016
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| US5930373A (en) * | 1997-04-04 | 1999-07-27 | K.S. Waves Ltd. | Method and system for enhancing quality of sound signal |
| US20070253576A1 (en) * | 2006-04-27 | 2007-11-01 | National Chiao Tung University | Method for virtual bass synthesis |
| CN102957988A (en) * | 2011-08-24 | 2013-03-06 | 半导体元件工业有限责任公司 | Audio signal processing circuit |
| CN102547517A (en) * | 2011-12-30 | 2012-07-04 | Tcl集团股份有限公司 | Bass signal harmonic generating method and device and sound playing equipment |
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Non-Patent Citations (1)
| Title |
|---|
| 周荣冠: "《心理声学低音增强技术的研究》", 《心理与生理声学》 * |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110957995A (en) * | 2019-10-25 | 2020-04-03 | 四川汇源光通信有限公司 | Distributed fault monitoring device IIR filtering system and design method thereof |
| CN113452158A (en) * | 2021-05-28 | 2021-09-28 | 北京理工大学 | Environmental electromagnetic wave energy acquisition system |
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Application publication date: 20180309 |