CN104363002A - Digital equalizer based method for processing sound effect by parameter transformation - Google Patents

Abstract

The invention discloses a digital equalizer based method for processing sound effect by parameter transformation. The method includes acquiring frequency f0 and gain G; transforming f0 and G values into omega 0 and K variables in a digital equalizer, and feeding the omega 0 and K variables back to a digital domain transfer function of the digital equalizer to make a response, wherein the digital domain transfer function is H(z)= , and the gamma is equal to sinh{[In(2)/2]bw[omega0/sin(omega0)]}sin(omega0); according to the created digital domain transfer function, processing a sound signal X(z) by a digital expression, as follows, corresponding to the digital equalizer to acquire a response result of the equalizer. The digital equalizer based method has the advantages that a sound effect processing method by which processed products have better sound effect than like products is realized, sound signals processed according to the sound effect processing method have the same sound effect as those processed by a conventional simulation equalizer, and bandwidth distortion of the like products is avoided.

Description

A kind of method by parameter transformation, audio processed based on digital equalizer

Technical field

The present invention relates to the method by parameter transformation, audio processed based on digital equalizer.

Background technology

At present, digital equalizer is on the market all adopt FIR filter, and its sense of hearing is obviously weaker than traditional analog filter, and analog filter is an iir filter in essence, therefore, has had a small amount of product to have employed the scheme of iir filter., also there is responsive bandwidth can produce distortion problem along with the increase of amplitude in IIR equalizer on the market at present, thus affect sense of hearing.

In addition, mostly digital equalizer is on the market the pattern adopting graphical hairclipper to regulate, and this design can exist following two problems, and one is that frequency resolution is too low, and two is must regulate multiple hairclipper simultaneously.In use, there is contradictory relation in this two problems, is difficult to unified to reach a good audio effect.

Summary of the invention

The object of the invention is to realize a kind of sound effect treatment method more excellent compared to like product sense of hearing effect, with traditional analog equalizer, there is consistent sense of hearing by the audio signal of this sound effect treatment method process, and the problem of bandwidth distortion can not be there is as other like products.

For achieving the above object, a kind ofly the method that audio processes to be comprised by parameter transformation based on digital equalizer:

(1) receive from abscissa value corresponding to touch screen and ordinate value, wherein, abscissa value represents frequency f ₀, ordinate represents gain G;

(2) to f ₀with the Ω that G value transform is in digital equalizer ₀with K variable, wherein,

ω ₀＝2πf ₀

${\mathrm{\Ω}}_0=2\arctan \left(\frac{{\mathrm{\ω}}_{0}T}{2}\right)$

K＝10 ^G/20dB

In above three formulas, ω ₀for the angular frequency of numeric field, T is the sampling period;

(3) by above-mentioned Ω ₀respond in the numeric field transfer function in digital equalizer with K variable feedback; Wherein numeric field transfer function is:

$H\left(z\right)=\frac{(1+\mathrm{\γ}\sqrt{K})-2\cos \left({\mathrm{\Ω}}_0\right)z^{-1}+(1-\mathrm{\γ}\sqrt{K})z^{-2}}{(1+\mathrm{\γ}/\sqrt{K})-2\cos \left({\mathrm{\Ω}}_0\right)z^{-1}+(1-\mathrm{\γ}/\sqrt{K})z^{-2}}$

In above formula, $\mathrm{\γ}=\sinh \left(\frac{\ln \left(2\right)}{2}\mathrm{bw}\frac{{\mathrm{\Ω}}_0}{\sin \left({\mathrm{\Ω}}_0\right)}\right)\sin \left({\mathrm{\Ω}}_0\right),$

Wherein, the response that H (z) is transfer function, z is the independent variable of Z-transformation, and bw is bandwidth, and described bandwidth is fixed value;

(4) according to above-mentioned constructed numeric field transfer function, adopt corresponding digital as follows of digital equalizer to process audio signal X (z), the response results of equalizer can be obtained, as shown in Figure 2.

Digital equalizer is made to have the effect consistent with analog equalizer by above-mentioned processing method, so user can obtain better sense of hearing in the process using equalizer, especially, when equalizing amplitude is larger, new distortion and noise can not be introduced like that to other digital equalizers.In addition, this processing method overcomes the problem of bandwidth distortion, because user in use, no matter which kind of amplitude digital equalizer is arranged on, and all can hear the same bandwidth product.Also there is higher frequency domain resolution simultaneously.

Further, obtain from abscissa value corresponding to touch screen and ordinate value through digital equalizer processes and displays.Be convenient to user and know the numerical value that digital equalizer is corresponding intuitively.

Further, described numeric field transfer function converts based on the transfer function of traditional analog equalizer, and wherein, the transfer function of traditional analog equalizer is:

$\hat{H}\left(s\right)=\frac{s^2+2\sqrt{K}\sinh \left(\frac{\ln \left(2\right)}{2}\mathrm{bw}\right){\mathrm{\ω}}_{0}s+{\mathrm{\ω}}_0^2}{s^2+\frac{2}{\sqrt{K}}\sinh \left(\frac{\ln \left(2\right)}{2}\mathrm{bw}\right){\mathrm{\ω}}_{0}s+{\mathrm{\ω}}_0^2}$

S in formula is the independent variable of Laplace transformation,

To the process that the transfer function of above-mentioned traditional analog equalizer converts be:

wherein, T is the sampling period, and z is the independent variable of Z-transformation,

$\mathrm{bw}\→\frac{{\mathrm{\Ω}}_0}{\sin \left({\mathrm{\Ω}}_0\right)}\mathrm{bw}.$

Which not only constructs a numeric field transfer function, also avoid the problem of bandwidth distortion.

Further, touch screen is to having high pitch controlled area and bass controlled area.Like this, user can be allowed to adjust low frequency and HFS easily.

Further, in the control area of touch screen, the abscissa value that touch screen is corresponding and ordinate value are determined in the position after adopting white point to move.The program is a kind of balanced control mode of full touch, and which can make user change amplitude and frequency two parameters with an action simultaneously, and meanwhile, which also has higher frequency domain resolution.

Accompanying drawing explanation

Fig. 1 is the schematic diagram of touch screen.

Fig. 2 is the response results schematic diagram of equalizer.

Embodiment

Below in conjunction with the drawings and specific embodiments, the present invention is further elaborated.

A kind ofly the method that audio processes to be comprised by parameter transformation based on digital equalizer.

(1) receive from abscissa value corresponding to touch screen and ordinate value, wherein, abscissa value represents frequency f ₀, ordinate represents gain G; In the present embodiment, as shown in Figure 1, touch screen, to having high pitch controlled area 11 and bass controlled area 12, is convenient to allow user make adaptive adjustment to low frequency and HFS.In the process, user can carry out different optimum configurations at the square areas dragging white point of low frequency or high frequency controlled area.Graphical touch-control part is responsible for obtaining the parameters constantly refreshed along with the action of user, and this parameter is passed to digital equalizer, and generates display numerical value, allows user learn current facilities.

(2) to f ₀with the Ω that G value transform is in digital equalizer ₀with K variable, wherein,

ω ₀＝2πf ₀

${\mathrm{\Ω}}_0=2\arctan \left(\frac{{\mathrm{\ω}}_{0}T}{2}\right)$

K＝10 ^G/20dB

In above three formulas, ω ₀for the angular frequency of numeric field, T is the sampling period.

(3) by above-mentioned Ω ₀respond in the numeric field transfer function in digital equalizer with K variable feedback; Wherein numeric field transfer function is:

$H\left(z\right)=\frac{(1+\mathrm{\γ}\sqrt{K})-2\cos \left({\mathrm{\Ω}}_0\right)z^{-1}+(1-\mathrm{\γ}\sqrt{K})z^{-2}}{(1+\mathrm{\γ}/\sqrt{K})-2\cos \left({\mathrm{\Ω}}_0\right)z^{-1}+(1-\mathrm{\γ}/\sqrt{K})z^{-2}}$

In above formula, $\mathrm{\γ}=\sinh \left(\frac{\ln \left(2\right)}{2}\mathrm{bw}\frac{{\mathrm{\Ω}}_0}{\sin \left({\mathrm{\Ω}}_0\right)}\right)\sin \left({\mathrm{\Ω}}_0\right),$

Wherein, the response that H (z) is transfer function, z is the independent variable of Z-transformation, and bw is bandwidth, and described bandwidth is fixed value;

When constructively stating numeric field transfer function, it converts based on the transfer function of traditional analog equalizer, and wherein, the transfer function of traditional analog equalizer is:

$\hat{H}\left(s\right)=\frac{s^2+2\sqrt{K}\sinh \left(\frac{\ln \left(2\right)}{2}\mathrm{bw}\right){\mathrm{\ω}}_{0}s+{\mathrm{\ω}}_0^2}{s^2+\frac{2}{\sqrt{K}}\sinh \left(\frac{\ln \left(2\right)}{2}\mathrm{bw}\right){\mathrm{\ω}}_{0}s+{\mathrm{\ω}}_0^2}$

In formula, s is the independent variable of Laplace transformation, ω ₀for the angular frequency that the centre frequency of equalizer hairclipper is corresponding, bw is corresponding bandwidth, and k is a variable relevant to gain G, and user is by the selection of equalizer hairclipper and locate and arrange above three parameters, the response of transfer function can be obtained, thus realize portfolio effect.

For the effect making digital filter have traditional analog filter, first need the digital filter transfer function that structure one is consistent with above-mentioned transfer function form, this can be obtained after bilinear transformation by above-mentioned transfer function.The bilinear transformation done is: wherein, T is the sampling period, and z is the independent variable of Z-transformation; Because above-mentioned bilinear transformation can introduce the problem of bandwidth distortion, the transfer function of structure can't directly use in practice, need do following precorrection process:

$\mathrm{bw}\→\frac{{\mathrm{\Ω}}_0}{\sin \left({\mathrm{\Ω}}_0\right)}\mathrm{bw};$

Above-mentioned numeric field transfer function is then obtained more than comprehensive.

(4) according to above-mentioned constructed numeric field transfer function, adopt corresponding digital as follows of digital equalizer to process audio signal X (z), the response results of equalizer can be obtained.Via speaker playback out, user just can hear corresponding audio to treated audio stream, as shown in Figure 2.

Digital equalizer is made to have the effect consistent with analog equalizer by above-mentioned processing method, so user can obtain better sense of hearing in the process using equalizer, especially, when equalizing amplitude is larger, new distortion and noise can not be introduced like that to other digital equalizers.In addition, this processing method overcomes the problem of bandwidth distortion, because user in use, no matter which kind of amplitude digital equalizer is arranged on, and all can hear the same bandwidth product.Also there is higher frequency domain resolution simultaneously.In addition, present embodiment is a kind of balanced control mode of full touch, and which can make user change amplitude and frequency two parameters with an action simultaneously, and meanwhile, which also has higher frequency domain resolution.

Claims (5)

1., based on the method that digital equalizer is processed audio by parameter transformation, it is characterized in that:

(1) receive from abscissa value corresponding to touch screen and ordinate value, wherein, abscissa value represents frequency f ₀, ordinate represents gain G;

(2) to f ₀with the Ω that G value transform is in digital equalizer ₀with K variable, wherein,

ω ₀＝2πf ₀

K＝10 ^G/20dB

In above three formulas, ω ₀for the angular frequency of numeric field, T is the sampling period;

(3) by above-mentioned Ω ₀respond in the numeric field transfer function in digital equalizer with K variable feedback; Wherein numeric field transfer function is:

In above formula,

Wherein, the response that H (z) is transfer function, z is the independent variable of Z-transformation, and bw is bandwidth, and described bandwidth is fixed value;

(4) according to above-mentioned constructed numeric field transfer function, adopt corresponding digital as follows of digital equalizer to process audio signal X (z), the response results of equalizer can be obtained, as shown in Figure 2.

2. the method processed audio by parameter transformation based on digital equalizer according to claim 1, be is characterized in that: obtain from abscissa value corresponding to touch screen and ordinate value through digital equalizer processes and displays.

3. the method by parameter transformation, audio processed based on digital equalizer according to claim 1, it is characterized in that: described numeric field transfer function converts based on the transfer function of traditional analog equalizer, wherein, the transfer function of traditional analog equalizer is:

S in formula is the independent variable of Laplace transformation,

To the process that the transfer function of above-mentioned traditional analog equalizer converts be:

wherein, T is the sampling period, and z is the independent variable of Z-transformation,

4. the method processed audio by parameter transformation based on digital equalizer according to claim 1, be is characterized in that: touch screen is to having high pitch controlled area and bass controlled area.

5. the method processed audio by parameter transformation based on digital equalizer according to claim 1, be is characterized in that: in the control area of touch screen, and the abscissa value that touch screen is corresponding and ordinate value are determined in the position after adopting white point to move.