KR20090086751A - Device of processing for audio signal and method thereof - Google Patents

Abstract

A device for processing audio signals and a method thereof are provided to effectively remove a cross talk of an audio signal regardless of a distance between speakers by removing a cross talk through a band pass filter, a delay part, and an amplifying part. A device for processing audio signals including a mixing part, a cross talk removing part(320), a band strengthening part(330), and an adding part(340). The mixing part forms an input signal having at least two channels as the number of desired output signals. The mixing part forms a mixed signal of 4 channels. The cross talk removing part removes a cross talk generated in the mixed signal. The band strengthening part strengthens a signal of a partial band among the signals in which the cross talk is removed. An output part outputs each signal in which the band is strengthened. The cross talk removing part includes a delay part and an amplifying part.

Description

DEVICE OF PROCESSING FOR AUDIO SIGNAL AND METHOD THEREOF

The present invention relates to an audio signal processing apparatus and a processing method thereof, and more particularly, to an audio signal processing apparatus for adjusting an audio signal having at least two channels for crosstalk removal and a processing method thereof.

When listening to a three-dimensional sound such as distance, direction, etc. in a natural state, both ears of the human body sense perceptual differences such as the phase and magnitude of the signals reaching each ear to perceive the sound in a three-dimensional form. Suitable for In addition, natural audio signals recorded using a two-channel microphone that mimics both ears or two-channel (stereo) audio signals that artificially give stereoscopic effect can be perceived in a three-dimensional form even if you listen to them with both ears using earphones. .

However, when listening to such stereoscopic sound through a two-channel speaker, the sound signal generated from the left and right speakers proceeds to the listener's ear and is mixed by interference in the space. Therefore, the two-channel sound signal generated by the speaker remains at the listening point. It will not be preserved. As a result, the three-dimensional sound recorded or generated in the two-channel form is damaged three-dimensional information corresponding to the three-dimensional feeling can not feel the three-dimensional feeling in the listening stage. Among the sound signals of each channel to be listened to, signals added and mixed in addition to the original signal are called crosstalk, and are generally removed using a transoral filter.

FIG. 1 is a schematic diagram showing front-sided multi-channel speakers, a listening point, and a space transfer function existing therebetween, and FIG. 2 is a schematic diagram showing a front-sided multi-channel speaker system including a crosstalk cancellation filter. 1 and 2, each speaker is denoted by V, and a listening point corresponding to both ears is denoted by P. FIG. In FIG. 1, the space transfer function matrix measured from the speakers to both ears is referred to as G, and the space transfer function from each speaker constituting the G matrix to each listening point is equal to g.

At this time, the crosstalk removal filter for crosstalk removal is an inverse function of the space transfer function, and the crosstalk removal filter C including the inverse function of the space transfer function has a matrix as follows.

When such a speaker system is installed in a TV or the like, the azimuth angle from the listening point to each speaker becomes smaller as the speaker spacing is considerably smaller than the distance to the listener. At this time, each of the head transfer functions (g1, g2, g3, g3) that will constitute the crosstalk elimination system becomes similar, so that the elements constituting the crosstalk elimination filter of Equation 1 diverge, making the system very difficult.

Accordingly, the technical problem to be achieved by the present invention is to provide an apparatus for processing an audio signal, which is not affected by speaker spacing and effectively eliminates crosstalk of the audio signal even in a narrow space.

In addition, another technical problem to be achieved by the present invention is a method of processing an audio signal that eliminates crosstalk while increasing the stereoscopic sense of a stereo signal using a band pass filter, a delay unit and an amplification unit without using a head transfer function. To provide.

Therefore, the audio signal processing apparatus of the present invention, in order to solve the above problems, a mixing unit for forming an input signal having at least two channels as the number of the desired output signal; A crosstalk removing unit for removing crosstalk generated in the mixed signals; A band enhancement unit for reinforcing a signal of a part of the band from which the crosstalk is removed; And an output unit for outputting each signal of which the band is enhanced.

According to the audio signal processing apparatus of the present invention, a speaker is formed by inputting a desired number of output signals from an input signal having at least two channels, and removing the crosstalk by using the band pass filter, the delay unit, and the amplification unit. Crosstalk of the audio signal can be effectively removed regardless of the arrangement of the and the distance between the speakers.

In addition, according to the audio signal processing apparatus of the present invention, for each signal from which crosstalk is removed, it is enhanced for a specific band in which the size of the signal is reduced more than necessary, and the output parts are disposed in front, thereby impairing the sound field of the audio signal. This can further increase the stereoscopic effect of the audio signal.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

The embodiments of the present invention are provided to more fully explain the present invention to those skilled in the art, and the following examples can be modified in various other forms, and the scope of the present invention is It is not limited to an Example. Like numbers refer to like elements in the figures.

The apparatus and method for processing an audio signal according to the present invention is an apparatus and method for eliminating crosstalk using a delay unit and an amplification unit, rather than a filter based on a head transfer function, for effective crosstalk elimination when the distance between speakers is small. It is about. In addition, the audio signal processing apparatus and method of the present invention specifically exemplify a crosstalk removal filter that outputs the same number of signals so that a stereo signal of two channels is received as an input and reproduced by a multichannel speaker.

FIG. 3 is a block diagram showing an audio signal processing apparatus of the present invention, which is a mixing unit 310 that combines two channel input signals into as many signals as desired to meet the crosstalk elimination process, and interference of sound signals. A crosstalk removing unit 320 for removing a crosstalk signal using a phenomenon, a band enhancing unit 330 for reinforcing a signal of a specific band weakened by the crosstalk removing unit, and a crosstalk removing unit and a band for forming a final output signal. The adder 340 adds the signal processed by the reinforcement unit.

4 shows the inside of the mixing unit 310 of the audio signal processing apparatus of the present invention. Referring to FIG. 4, the mixing unit 310 is an apparatus that arithmetically combines as many signals as the number of speakers using a two-channel input signal. In the embodiment of the present invention, four mixing signals are formed. The mixing unit 310 uses an amplifier and an adder for arithmetic the input signal. Of the four mixing signals, the mixing signals V1 and V4 for the speaker located at the outside use the input signals Left and Right, and the mixing signals V2 and V3 for the speaker located inside are the input signals ( Left, Right) are created by combining appropriately. The combination of input signals for the mixing signals V2 and V3 is set in consideration of the characteristics, the magnitude of the input signal, the position of the speaker, and the distance between the speakers. The number of mixing signals of the mixing unit 310 is not limited thereto, and may be composed of mixing signals formed by combining an input signal and a mixing signal that outputs an input signal as it is.

5 illustrates a crosstalk canceling unit 320, a band enhancement unit 330, and an adder 340 in the audio signal processing apparatus of the present invention. First, among the audio signal processing apparatuses including the general crosstalk removing filter, the crosstalk removing filter includes a matrix filter as shown in Equation (1). Referring to Equations 1 and 5, the head transfer function corresponding to V1 and V4 is selectively used to generate output signals for the outer speakers V1 and V4, and the inner speakers V2 and V3. The head transfer function corresponding to V2 and V3 is optionally used to generate an output signal for the signal. That is, crosstalk removal processing for V1 and V4 and crosstalk removal processing for V2 and V3 may be separately performed. In addition, when the distance between the speaker and the listener is farther than the distance between the speakers, g ₁ and g ₄ in the head transfer functions become similar, so that the construction of 1 / (g ₁ -g ₄ ) necessary for crosstalk removal is impossible. Therefore, the crosstalk cancellation unit of the audio signal processing apparatus of the present invention crosstalks for V1 and V4 by multiplying the crosstalk removal filter with | g1 -g4 | using the band filter unit, the delay unit, the amplifier unit, and the adder unit. The effect of approximating the removal process can be performed. This crosstalk processing for V1 and V4 uses a method of approximating using a delay unit and an amplification unit.

In addition, in the audio signal, crosstalk does not occur in all areas, but the band of the signal in which crosstalk occurs intensively varies according to the characteristics of the audio signal, the arrangement and the spacing between the speakers. Accordingly, the crosstalk canceling unit of the audio signal processing apparatus of the present invention has a band separator for separating the specific band effective for crosstalk removal for each mixed signal formed by the mixing unit 310 in front of the delay unit and the amplifier. To place.

Each of the mixed signals V1 to V4 is formed of two separated signals by the band separator. One of the separated signals will perform delay and amplification, and the other may not involve delay and amplification.

In addition, each of the mixed signals V1 to V4 adds the delayed and amplified signal to the unmodified signal among the other mixed signals through the delay unit and the amplification unit. For example, signals passing through BPF1 and BPF4 pass through the delay and amplification sections to band-out the outer signals V1 and V4, which do not involve delay and amplification of the signals passing through BPF1 and BPF4, respectively. It is added to the unsigned signal to form intermediate output signals V1_1 and V4_1. In addition, the signals passing through the BPF2 and the BPF3 pass through the delay unit and the amplification unit to band-segregate the inner signals V2 and V3, and these are respectively applied to the signals without the delay and amplification among the signals passing through the BPF2 and the BPF3, respectively. Are added to form intermediate output signals V2_1 and V4_1. Through this process, the processing autonomous of the audio signal of the present invention can remove the crosstalk of the mixed signal using the band separator, delay unit, amplification unit, and adder without using the transorder filter as the crosstalk elimination filter. It becomes possible. In addition, the cutoff frequency, delay amount, amplification degree, etc. of the band pass filter can be adjusted according to the arrangement and performance of the speakers.

3 and 5, the signals V1 to V4 mixed by the mixing unit 310 may be input to the crosstalk removing unit 320 and may be input to the band enhancement unit 330. The band enhancer 330 reinforces a component corresponding to a specific frequency band to compensate for the characteristic of the crosstalk remover 320. The crosstalk remover 320 has a property similar to that of the differentiator, and the mixed signal passed through the crosstalk remover 320 is a component of a specific band according to characteristics of an input signal of two channels such as an audio signal passed through the differentiator. Can be weakened. Therefore, in order to compensate for the weakening of the specific band component, the band enhancement unit 330 serves to reinforce the component corresponding to the band being weakened. Therefore, the band enhancer 330 includes a band separator, a delay unit, and an amplifier. First, the mixing signal received from the mixing unit 310 separates a band corresponding to a band requiring enhancement for each mixing signal from the band separating units BPF5, BPF6, BPF7, and BPF8, and processes the crosstalk removing unit. The signal is passed through the delay section for synchronization with the result, and then through the amplification section for adjusting the degree of band enhancement. In addition, according to the arrangement and performance of the speakers, the cutoff frequency and delay amount of the band pass filter in the crosstalk canceling unit 320, and the setting of the amplification degree, the blocking of the band pass filter in the band enhancer 330. Frequency, delay amount, amplification degree, etc. can be adjusted.

The adder 340 adds the mixed signals V1_1 to V4_1 through the crosstalk eliminator 320 and the mixed signals V1_2 to V4_2 through the band enhancer 330. The mixing signals are added for each of the signals V1 to V4 output from the mixing unit 310 to form final output signals V1 'to V4'.

The final output signals (V1 'to V4') passing through the crosstalk removing filter do not use a conventional transorder filter, but use a delay unit, an amplifier unit, and an adder unit, and thus, the distance between the speaker and the listener and the distance between the speakers. The head transfer function, which cannot be measured by distance, can be avoided, and crosstalk cancellation can be implemented in real time without using a high performance dedicated computing device such as a digital signal processor (DSP). In addition, a cost reduction effect can be obtained by using the simplest components such as a delay unit, an amplifier unit, and an adder unit.

In addition, the audio signal processing apparatus of the present invention can be applied to an audio and video system in the following form. First, in an audio and video system equipped with a multi-channel speaker system, a process of removing crosstalk of an audio signal may be performed by using an idle computing capability of a processor of the system. In this case, the audio signal processing apparatus of the present invention is composed of a low order band pass filter, a delay unit, an adder, and the like, so that the amount of computation required for processing is very small. Therefore, it is possible to drive sufficiently only by the general idle computing capability provided by the audio and video system without requiring a separate component. At this time, when a command for performing crosstalk removal is input from the outside, the processor receives an audio signal from a memory, removes crosstalk, and converts and outputs a result signal in a form suitable for an output unit. You can get a signal.

Second, in an audio and video system equipped with a multi-channel speaker system, by processing the audio signal processing apparatus of the present invention in an associated processor (co-process) rather than the process of the system itself, crosstalk cancellation processing can be performed. Can be. When a command for externally performing crosstalk is input, the processor of the system instructs the associated processor to perform crosstalk processing. In addition, after the crosstalk processing is performed, the output signal, which is a result thereof, may be received by the associated processor from the processor of the system, and may be output by converting the result signal into a form suitable for the output unit.

Third, the audio signal processing apparatus of the present invention may be implemented in hardware using an electric circuit, and may be installed in an audio and video system equipped with a multi-channel speaker system to perform crosstalk cancellation. When a command for performing crosstalk removal is input from the outside, the audio signal passes through the crosstalk removing device (circuit) and then outputs a result signal to the output terminal.

In addition, the audio signal processing apparatus of the present invention may perform crosstalk removal on an input signal and store the result in a storage unit, so that the audio signal processing apparatus may be used for crosstalk removal of an audio signal later.

In the above, when the input signal is a stereo two-channel signal, the audio signal processing apparatus for crosstalk removal has been described. Hereinafter, a device and method for effectively removing crosstalk while playing 5.1 channel audio content through a front-sided multichannel speaker system will be described as in movie contents commonly used in the form of a DVD.

 Dolby Digital (DD), which supports surround playback using multiple separate audio channels, is often referred to as 5.1-channel audio, developed and widely used as an audio format for DVD, HDTV, and satellite broadcasting. It is becoming. This 5.1-channel audio is widely used with the expansion of home theaters, and the front, left and right two-channel (FL, FR), front-center having frequency band information up to 220-20,000 (Hz). 5 channels of audio signals, 1 channel (CC), 2 channels (SL, SR), and 2 channels (SL, SR) and 0.1 channel (Low Frequency Effects) up to 20-120 (Hz). The audio signals of BA) are collectively added together.

This 5.1-channel audio system does not simply divide an arbitrary sound into several speakers, but separates and records each corresponding channel from the time of making a DVD, and multi-channel audio recorded separately to a speaker corresponding to each channel. By reproducing, a realism and a three-dimensional feeling can be felt at the time of listening. Therefore, in order to feel the sound field of the 5.1-channel audio signal, the listener separately installs a home theater speaker system in addition to the sound reproduction value included in the TV system. However, in this case, as well as the economic burden of configuring a separate speaker system, and without having to purchase a home theater system, it is necessary to use a separate audio cable and a speaker to plan a flat speaker layout, so as to utilize the space You will be constrained. Accordingly, an apparatus for processing an audio signal according to another embodiment of the present invention relates to an apparatus and method for arranging a multichannel speaker linearly in front for reproduction of a 5.1 channel audio signal.

6 is a block diagram illustrating an audio signal processing apparatus according to another embodiment of the present invention mentioned above, and FIG. 7 illustrates an audio signal processing apparatus according to another embodiment of the present invention.

6 and 7, the audio signal processing apparatus of FIG. 6 includes a mixer 610 and 710, a crosstalk remover 620 and 720, a band enhancer 630 and 730, and an adder 640 and 740. Band separators 621 and 721, delay units 622 and 722, amplifiers 623 and 723, and adders 624 and 724 included in the crosstalk removing unit 620 and 720; Band separation units 631 and 731, delay units 632 and 732, and amplifiers 633 and 733 included in the band enhancement units 630 and 730; Functions and configurations of the adders 640 and 740 are the same as those of the corresponding elements of FIG. 5, and thus, detailed descriptions thereof will be omitted.

First, referring to FIG. 6, the mixing unit 610 first receives an audio signal consisting of 5.1 channels, and mixes to form four channels of mixing signals V1 to V4. In the mixing unit 610, FL, FR, CC, BA, SL, SR indicate signals of the front left, front right, center, bass effect, rear left, and rear right channels, respectively. SIP (Sound Image Positioning) is a portion for performing sound stereoposition processing, and configures the mixing unit 610 with an adder. In addition, the mixing unit 610 plays a role of giving a stereoscopic effect to the mono signals to effectively reproduce the 5.1-channel audio signal composed of six mono signals using four speakers arranged in front. As illustrated in FIG. 4, the SIP of FIG. 6 may use a circuit unit that forms four mixed signals using a delay unit, an amplifier unit, and an adder unit in the front left, front right, rear left, and rear right channels. The mixing signal formed by the mixing unit 610 removes the crosstalk generated by the crosstalk remover 620, and when the crosstalk remover removes the crosstalk from the band enhancer 630, the band is weakened. In operation 640, corresponding signals are added among the signals output from the crosstalk remover 620 and the band enhancer 630.

In this case, the adder 640 outputs the result signals V1_1 to V4_1 of the crosstalk remover 620, the result signals V1_2 to V4_2 of the band enhancer 630, and the mixing unit. The final output signal is generated by adding the signals V5 of the center (CC) and bass effect (BA) speakers. The signals of the center and bass effect speakers can be adjusted by the amplification unit for each signal, which can be set differently according to the speaker arrangement.

In addition, referring to FIG. 7, the mixing unit 710 forms a mixed signal in a form similar to the mixing unit 610 of FIG. 6. The method of forming the four-channel mixing signal is the same as that of the audio signal processing apparatus of FIG. 6, but the signals V4 and V5 of the center (CC) and bass effect (BA) speakers are not added by the mixing unit 710. Otherwise, it can be added later to the final output signal. For example, the signal V5 of the bass effect BA speaker may be added to the second and third mixing signals of the four channel mixing signals by the adder 724 of the crosstalk canceling unit 720, and the center CC. The signal V6 of the speaker may be added to the first and fourth output signals of the four final output signals by the adder 740 to form a final output signal. At this time, the signal of the center and bass effect speakers, as well as the amplification ratio can be adjusted by the amplification unit for each signal, which may be set differently according to the speaker arrangement.

The present invention described above is not limited to the above-described embodiment and the accompanying drawings, and various substitutions, modifications, and changes are possible within the scope of the technical idea of the present invention. It will be clear to those of ordinary knowledge.

1 and 2 show an overview of the operation of the transoral filter to eliminate the occurrence of crosstalk.

3 illustrates an apparatus for processing an audio signal according to an embodiment of the present invention.

4 illustrates a mixing unit of an audio signal processing apparatus according to an embodiment of the present invention.

5 illustrates a crosstalk removing unit, a band enhancement unit, and an adder in an audio signal processing apparatus according to an embodiment of the present invention.

6 illustrates an audio signal processing apparatus according to another embodiment of the present invention.

7 shows an apparatus for processing an audio signal according to another embodiment of the present invention.

Claims (13)

A mixing unit which forms an input signal having at least two channels as many as desired output signals; A crosstalk removing unit for removing crosstalk generated in the mixed signals; A band enhancement unit for reinforcing a signal of a part of the band from which the crosstalk is removed; And An output unit for outputting each signal of which the band is enhanced; Apparatus for processing an audio signal comprising a. The method of claim 1, And the mixing unit forms a mixed signal of four channels. The method of claim 2, And said mixed signal comprises a signal formed by combining said input signal. The method of claim 2, The mixed signal includes a signal formed by using the input signal as it is. The method of claim 1, The crosstalk canceling unit includes a crosstalk canceling filter unit for separating a specific band of each of the mixed signals. The method of claim 1, The crosstalk canceling unit may include a delay unit for delaying the separated signal; And an amplifier for amplifying the delayed signal. The method of claim 6, And the crosstalk canceling unit sets a delay degree of the delay unit and an amplification degree of the amplification unit according to an arrangement type of output units outputting the mixed signals. The method of claim 1, And the band enhancement unit includes a band enhancement filter unit for separating a specific band of each of the mixed signals. The method of claim 1, The band enhancement unit delay unit for delaying the separated signal; And An amplifier for amplifying the delayed signal Apparatus for processing an audio signal comprising a. Mixing an input signal having at least two channels by the number of desired output signals; A crosstalk removing step of removing crosstalk by separating, delaying, and amplifying a first band of each of the mixed signals; And A band enhancement step of separating a second band of each of the mixed signals by delaying and amplifying the predetermined band; Audio signal processing method comprising a. The method of claim 9, The mixing step forms a mixed signal of four channels from the input signal. The method of claim 10, The forming of the mixed signal is performed by combining the input signal. The method of claim 10, And the forming of the mixed signal is performed using the input signal as it is.

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