KR20060096574A - Apparatus and method of processing in digital audio signal - Google Patents

Abstract

The present invention relates to digital audio signal processing. The present invention relates to analog audio processing of a received signal, and then performs A / D conversion, and then determines whether the converted audio signal is mono / stereo and outputs the corresponding audio signal. An export digital mono / stereo detector; It provides a digital audio signal processing apparatus comprising a digital signal processing unit for receiving the output of the detection unit and processing the digital signal output.

Therefore, according to the present invention, it is possible to compensate for erroneous mono / stereo determination in the analog processing unit, and it is possible to automatically determine whether or not mono / stereo even when the related information cannot be obtained in the analog processing unit.

Digital audio signal processor

Description

Apparatus and Method of Processing in Digital Audio Signal

1 is a block diagram of a digital audio signal processing apparatus according to the prior art

2 is a block diagram of a digital audio signal processing apparatus according to the present invention;

Figure 3 is a block diagram of the internal configuration of the digital mono / stereo detection unit according to the present invention

4 is a flowchart illustrating a processing procedure in a digital mono / stereo detector according to the present invention.

* Explanation of symbols for the main parts of the drawings

10 demodulator 20 stereo detector

30: mono / stereo converter 40: A / D converter

45: digital mono / stereo detector 50: digital signal processor

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a digital audio processing device. More particularly, the present invention relates to a mono / mono in an audio processing device which receives an analog-to-digital (A / D) -converted pulse code modulation (PCM) signal as an input. The present invention relates to automatically determining whether a stereo is used for later processing.

Audio processing apparatus comprising a device for detecting mono / stereo in connection with the present invention is known from US Patent Application Nos. 5,655,025 and Korean Patent Publication Nos. 2001-0087659 and 2002-0028897.

However, all of the known inventions are mono / stereo by detecting an input signal or recognizing a connector type having a physically different form when a signal is input to only one of two channel inputs by an analog circuit. Whether or not to detect.

In addition, Korean Patent Publication Nos. 1999-0067158 and 2000-0034579 disclose pilot signals indicating whether mono / stereo is received from radio waves received by an application such as an FM radio receiver or a television receiver. The present invention relates to a method of demodulating (demodulation) to select whether or not the mono / stereo, the disclosed invention is known a method for solving the selection error that occurs when the radio wave reception sensitivity of the receiver is poor.

Hereinafter, a structure of a digital audio signal processing apparatus according to the prior art will be described with reference to the accompanying drawings. FIG. 1 is a block diagram of a digital audio signal processing apparatus according to the prior art.

The configuration block diagram is a configuration block diagram for transmitting signals and information to the digital processing unit by performing stereo and mono detection in the analog processing unit.

Referring to FIG. 1, a demodulator 10 includes a stereo detector 20, a stereo detector 20, a mono / stereo converter 30, an A / D converter 40, and a digital signal processor 50.

The demodulator 10 functions to demodulate a signal input to the receiving device through an antenna.

The stereo detector 20 functions to detect whether a received input signal is mono / stereo.

The mono / stereo converter 30 determines whether the signals input to A / D convert the signal demodulated by the demodulator 10 are mono or stereo and informs the stereo detector 30 according to the determination result. It converts it to mono or stereo.

The A / D converter 40 functions to convert an analog signal into a digital signal in order to process the signal in the analog processing unit that has passed through the mono / stereo converter 30 in the digital processing unit.

The digital signal processor 50 receives the mono / stereo information determined by the stereo detector 20 and processes the digital signal using the A / D converted signal.

However, looking at the analog processing method according to the prior art using the configuration block and the processing method as described above, the detection method in the analog as described above is not made through the comparison of the left / right two channel signals, it is a separate pilot If a pilot signal is present using a pilot signal (a kind of flag indicating presence or absence), it is determined to be left / right stereo, and if it is not present, it is determined to be mono.

Looking at the stereo transmission and reception method in the analog broadcast, for example, in the FM radio, in the transmission frequency band is transmitted in the order of (M) (S) (P), where M is the middle signal, S Is a side signal, P is a pilot signal.

In this case, the transmitting terminal encodes and transmits M = (L + R) / 2 and S = (L-R) / 2.

If there is a signal corresponding to (P), the receiver determines that it is a stereo and outputs L = M + S and R = M-S, and if the signal corresponding to (P) If is not present, it is determined to be mono and outputs L = M and R = M.

The above-described transmission scheme is transmitted as described above for compatibility with the mono FM receiver. That is, the mono receiver always outputs only M.

Therefore, even if the original source is mono, the transmitting end (broadcasting station) transmits unconditionally by the above method, and the receiver always receives only a signal determined to be stereo. For example, something like news is actually a mono source.

In the case of a television (TV), the transmission method is the same. Unlike FM radio, there is a case of transmitting in mono, stereo, or voice multiplexing. In the case of transmitting in any of the above manners, it can be determined only by the pilot in analog detection, but the pilot may be wrong.

In other words, it is called stereo, but when the left / right are the same mono signal or because of problems such as reception sensitivity, the M channel is unharmed. There is a problem that can occur if the sound quality is very poor.

As another example, when receiving a signal at the line input (headphone jack), there is an analog method of making a stereo decision based on the physical appearance. However, even in the case of the above method, when a source is actually used to transmit a mono, but a stereo jack is used, there is a problem in that it is determined to be stereo.

Or in some cases there is no prior information, and there may be two signals coming into the left and right channels.

Thus, even though the analog processor recognizes the received input signal as a stereo and A / D converts the signals of the two channels to provide them to the digital processor, the signals of the two channels are actually the same mono. There may be a problem.

In addition, when the reception sensitivity of the receiver is poor, the sound quality may worsen when playing in stereo, and in some cases, the mono signal of the signal input to the digital signal processing terminal may be generated. There is a problem that information about stereo or not is unknown.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to provide a function for discriminating mono / stereo from digital audio signals of two channels input regardless of mono / stereo recognition at an analog stage. There is a purpose.

Another object of the present invention is to provide a function of determining whether mono / stereo is used using only signal characteristics of two input channels.

It is still another object of the present invention to provide a function for detecting a mono signal that is incorrectly recognized as stereo.

In order to achieve the above object, the present invention is analog mono-processed to the received signal, the A / D conversion, and then to determine whether the mono / stereo for the converted channel audio signal and outputs the output according to each of the digital mono / A stereo detector; It provides a digital audio signal processing apparatus comprising a digital signal processing unit for receiving the output of the detection unit and processing the digital signal output.

The digital mono / stereo detector comprises: an L / R correlation analyzer for calculating and outputting an autocorrelation value and a cross correlation value for each channel of the input channel audio signal; A mono / stereo decision unit which finally determines whether the current channel is mono / stereo by using the output autocorrelation value and the cross correlation value; And an output channel generator for generating an output by combining input channels according to the determination of the determination unit.

The determination result of the mono / stereo determination unit and the output of the output channel generator are transmitted to the digital signal processor for use in digital signal processing.

It is another object of the present invention to perform A / D conversion on an analog signal to a received signal, and then obtain a autocorrelation value and a cross-correlation value in the current channel to determine whether the converted signal is mono / stereo. Steps; A second step of determining whether mono / stereo is obtained using the obtained autocorrelation value and cross correlation value; And a third step of generating and transmitting an output signal by combining the input signals according to the determination, and providing a digital audio signal processing method.

In the second step, the obtained autocorrelation value and cross-correlation value are compared with a threshold set in the receiving apparatus and simplified to 0 and 1, and then the mono / stereo determination is made using the simplified value. It features.

If the correlation values are smaller than the threshold value set in the receiver, the simplification value is set to '0', and if the correlation values are larger than the threshold value set in the receiver, the simplification value is set to '1'. .

In addition, the terminology used in the present invention is a general term that is currently widely used as possible, but in certain cases, the term is arbitrarily selected by the applicant, and in this case, since the meaning is described in detail in the corresponding part of the present invention, a simple term It is to be clear that the present invention is to be understood as a meaning of terms rather than names.

The same components as in the prior art are given the same names and the same reference numerals for convenience of description, and detailed description thereof will be omitted.

According to the present invention, in order to solve the problem of discriminating the mono / stereo error caused when the digital signal is processed by the mono / stereo information already determined by the conventional analog processor, the present invention converts the received signal by analog processing to A / D conversion and then converts the converted signal. The present invention relates to a method and apparatus for automatically detecting mono / stereo using two input digital audio signals.

Hereinafter, a preferred embodiment of the present invention with reference to the accompanying drawings, Figure 2 is a block diagram of a digital audio signal processing apparatus according to the present invention.

In the block diagram, the stereo detector 20, which has been in the conventional analog processing stage, is different in the present invention from the digital processing unit.

Looking at the signal processing process in the digital audio signal processing apparatus according to the present invention, after demodulating the audio signal of the channel received through the antenna to convert the analog signal through the A / D converter 40, the conversion The input signal is processed through the digital mono / stereo detector 45 and the digital signal processor 50 constituting the digital signal processor.

The digital mono / stereo detector 45 determines whether a mono / stereo signal is input to two channel audio signals input between the output of the A / D converter 40 and the digital signal processor 50 without any external information. It is characterized by exporting the proper output according to.

The digital signal processor 50 receives the output of the detector 45 and processes the digital signal accordingly. The digital signal processor is referred to as digital audio compression, 3D sound field control, Refers to performing A / V content genre analysis.

The detailed configuration of the digital mono / stereo detector 45, which is a component block for digital mono / stereo detection according to the present invention, will be described with reference to the accompanying drawings. FIG. 3 is a digital mono / stereo detector 45 according to the present invention. ) Is a block diagram of the internal configuration.

The digital mono / stereo detector 45 is composed of an L / R correlation analyzer 100, a mono / stereo determiner 110, and an output channel generator 120.

The L / R correlation analyzer 100 receives two channel audio signals Lin and Rin input to the digital mono / stereo detector 45 to cross-correlate values between respective channels and the left and right channels. Obtaining and outputting.

The mono / stereo determination unit 110 uses the output of the correlation left (CL), the correlation right (CR), and the correlation cross (CX) that are outputs according to the analysis result of the correlation analyzer 100 to output the mono of the current channel. It is characterized in that the final decision whether or not stereo.

Also, the mono / stereo determination unit 110 transmits the determined mono / stereo determination information as additional information to the digital signal processing unit 50.

The output channel generator 120 generates the output signals Lout and Rout by combining the two input audio signals Lin and Rin according to the mono / stereo determination by the mono / stereo determination unit 110. The digital signal processor 50 may be output to the digital signal processor 50.

Hereinafter, the detailed operation of the internal configuration of the digital mono / stereo detector corresponding to the core part of the present invention will be described using equations and tables.

A method of obtaining autocorrelation values and cross-correlation values in the L / R correlation analyzer 100 will be described.

First, the reason for obtaining the correlation value is that if the samples in the time domain, for example, two samples L [n] and R [n] continue to be correlated, the two samples may be determined to be similar. In other words, as the correlation between the samples increases, the similarity increases, and then the two samples are the same.

Thus, if the two samples are the same, it is mono, and if they are different, it is stereo, so the correlation is calculated as above.

The L / R correlation analyzer 100 calculates an autocorrelation value of each of two input audio signals Lin and Rin and a cross correlation between the two signals. The cross-correlation value calculates only correlations between current samples without considering delay.

Accordingly, the autocorrelation value corresponds to the section energy of the corresponding channel, and the cross correlation value corresponds to the dot product of two channels.

There may be various methods for calculating the correlation value, but in the present invention, a method of processing in a sample unit and a method of processing in a section unit will be described as an example.

First, a method of obtaining a correlation value in sample units will be described with reference to the following equation.

[Equation 1]

,

은 각각 두 입력 오디오 신호인 Lin과 Rin 채널의 현재 샘플을 나타내며, 상기

는 상관값의 갱신 속도를 조절 할 수 있는 지연 계수를 나타낸다.In Equation 1

,

Represents the current samples of the two input audio signals, Lin and Rin channels, respectively.

Denotes a delay coefficient that can adjust the update rate of the correlation value.

가 1에 가까울수록 갱신 속도가 느려지고, 반대로 상기

가 0에 가까울수록 갱신 속도는 빨라진다. 또한 연산량에 따라 n의 간격 조절도 가능하다.That is

The closer to 1, the slower the update rate.

The closer to is 0, the faster the update rate. In addition, the interval of n can be adjusted according to the calculation amount.

That is, the amount of calculation in the correlation unit will vary according to the calculation interval such as calculation for every sample or once for every 10 samples, and the complexity thereof will also vary.

은 n 샘플까지의 자기 상관값을 말하고, 상기

은 현재 구하고자 하는 n 샘플 바로 이전까지의 자기 상관값을 나타낸다.For example, (1) of Equation 1 will be described first.

Is the autocorrelation value up to n samples,

Denotes the autocorrelation value up to immediately before the n samples to be obtained.

은 입력되는 신호는 시간 영역에서 양의 부분과 음의 부분으로 구성될 수 있고, 이 경우 만약 어느 구간 동안의 평균값을 구하면 0이 나올 수도 있어 상관값을 구하지 못할 수도 있는바, 이러한 문제점을 해결하기 위해 상기와 같이

즉, 자기 자신을 제곱함으로써 음의 부분을 없애서 상기와 같은 문제점을 해결한다.And the above

The input signal may be composed of a positive part and a negative part in the time domain, and in this case, if the average value is obtained for a certain period, 0 may be obtained and thus a correlation value may not be obtained. As above

In other words, by solving the above problem by eliminating the negative part by squared itself.

Also, by squaring oneself as above, this value represents the energy value of the magnetic signal in the current sample.

를 0.99라고 만약 가정하면 상기 식 (1)은 CL[n]= 0.99CL[n-1] + 0.01ㆍl[n]ㆍl[n]와 같이 표현되고, 이것은 현재 샘플 n 바로 이전까지의 상관값을 99%반영하고, 나머지 1%를 현재 샘플값을 반영한다는 의미이다. 그래서, 상기

값을 메모링 팩터(memorying factor) 또는 포게팅 팩터(forgetting factor)라고도 한다.Therefore, now, when the overall description of Equation (1) in Equation 1 is given,

Is 0.99, the equation (1) is expressed as CL [n] = 0.99 CL [n-1] + 0.01 · l [n] · l [n], which correlates immediately before the current sample n. The value reflects 99% and the remaining 1% reflects the current sample value. So, remind

The value is also called the memorying factor or the forgetting factor.

This is because if the delay coefficient α is not used as described above, the calculation amount is increased and time is required by obtaining the value from the beginning for every sample.

는 상기 각 어플리케이션(application)마다 미리 설정해 놓는 값으로서, 상술한 바와 같이 상기

값에 따라 상기 수학식의 샘플값이 갱신되는 속도가 바뀌게 되는바 상기

값은 설정자가 실험에 의한 성능과 연산량을 고려하여 최적의 값을 사용하여 장치에 설정해야 한다.And the above

Is a value set in advance for each of the applications, as described above.

The rate at which the sample value of the equation is updated depends on the value.

The value should be set by the setter using the optimal value considering the experimental performance and the amount of computation.

The remainders (2) and (3) are also obtained as in the equation (1) described above.

In the above description, a method of obtaining a correlation value in units of samples is described. Now, a method of obtaining a correlation value in units of intervals will be described.

A method of obtaining a correlation value in units of intervals may be obtained by using the following equation.

In the above, the interval is a length of a sample and refers to a bundle unit of a sample for obtaining the correlation value.

[Equation 2]

값은

번째 구간임을 나타내는 인덱스이며, 상기 구간의 길이는

값으로 결정한다.From above

The value is

Is an index indicating the second interval, and the length of the interval is

Determined by the value.

값은 실험에 의해 성능과 연산량을 고려하여 어느 정도 길이만큼 샘플들을 묶어 계산하면 될 지에 대한 최적값으로, 이 역시 어플리케이션(application)마다 미리 설정해 놓는 값이다.remind

The value is an optimal value for how long the samples should be bundled and calculated in consideration of the performance and the amount of calculation by experiment. This value is also set in advance for each application.

값이나 수학식 2에서의

값은 모두 상술한 바와 같이 최적의 값을 미리 어플리케이션에 설정해 놓는 값으로서, 상기 값들을 만약 너무 작거나 크게 하면 오디오 연결이나 끊김에 민감하게 반영함으로 인해 디지털 신호 처리시 오동작을 일으킬 수 있다.In the above Equation 1

Value or in equation (2)

As described above, all of the values are set in advance to an optimum value in the application. If the values are too small or large, the values may be sensitive to audio connection or disconnection, which may cause a malfunction in digital signal processing.

,

,

를 생성하고, 상기 출력은 상기 모노/스테레오 결정부(110)로 전송되어 모노/스테레오 여부를 최종 판별하기 위한 지표로 사용된다. Correlation values of the sample unit or the interval unit obtained through Equation 1 or 2 are output from the L / R correlation analyzer 100.

,

,

Is generated, and the output is transmitted to the mono / stereo determination unit 110 and used as an index for final determination of mono / stereo.

Various methods may be used to determine whether a mono / stereo is used by using the output of the correlation analysis result of the L / R correlation analyzer 100 as an input of the mono / stereo determiner 110.

Among the various methods, selection and adjustment are possible according to the level to be determined, the interval to be determined, the amount of calculation, and the like.

Now, a method of analyzing the obtained correlation value will be described as a process for obtaining mono / stereo using the autocorrelation value obtained using Equation 1 or 2.

That is, the present invention simplifies the correlation analysis result back to a binary value of 0 and 1 by a threshold value (TL) for convenience of explanation, and then uses a simple discrimination method using only this value as an embodiment.

The threshold value TL is a value that is set in advance for each application, and serves as a reference for determining whether the obtained correlation value is closer to L or R.

Looking at the pseudo C-code associated with the determination method is as follows.

if (CL [n]> TL)

    DL [n] = 1;

else

    DL [n] = 0;

이 어떤 임계값 TL보다 크면 이진값 DL[n] = 1, 작거나 같으면 DL[n] = 0이라고 하고, 상기

및

에 대해서도 같은 방법으로 DR[n] 및 DX[n]를 계산하면, DL, DR, DX 값의 조합에 따라 하기의 표 1과 같은 분석 결과를 얻을 수 있게 된다.That is, when describing the pseudo C-code, an autocorrelation value for Lin which is an input audio signal

Is greater than a certain threshold TL, the binary value DL [n] = 1, and less than or equal to DL [n] = 0.

And

If DR [n] and DX [n] are calculated in the same manner, the analysis results shown in Table 1 below can be obtained according to the combination of DL, DR, and DX values.

DL DX DR Explanation Sole determination Cumulative Discrimination 0 0 0 No input signal or stereo Mute (empty)  E = 3, S = 1 0 0 One R channel only signal present mono (R)  R = 3 0 One 0 Theoretically impossible mono (L + R)  M = 3 0 One One Mono (R) or stereo mono (R)  R = 1, S = 1 One 0 0 L channel only signal present mono (L)  L = 3 One 0 One Full stereo (dual mono) Stereo  S = 4 One One 0 Mono (L) or stereo mono (L)  L = 1, S = 1 One One One Mono with L = R mono (L or R)  M = 3

Referring to Table 1, this will be described by using two types of independent discrimination and cumulative discrimination as an example, the values of Table 1 are defined by the setter, the present invention will be described as defined in Table 1.

First of all, the above-described discrimination method will be described in relation to a single discrimination method. For example, the simplified correlation values DL, DX, and DR are used by comparison with a threshold using the obtained correlation value. In the case of DR) = (0, 0, 1), since only the Rin signal is a valid mono input since energy above the threshold (TL) exists only in the right (R) channel, it is represented as mono (R).

In the case of (DL, DX, DR) = (1, 0, 1), a valid input signal exists in both the left and right channels, and since there is no correlation, it is determined that the left and right channels are independent stereo (or dual mono). Can be lowered.

In addition, if (DL, DX, DR) = (1, 1, 1), a valid input signal exists in both the left and right channels, and the correlation is high. In this case, the same input is input to the left and right channels. It can be considered a signal.

In this way, independent determination was made. However, when the output of the output is determined according to the result of the correlation analysis for each sample or section, the mono / stereo switching is frequently performed in one audio content, so the sound quality deteriorates. I can do it.

Thus, in the present invention, a method of accumulating the determination result and statistically observing the accumulated value as a method for reducing sound quality deterioration resulting from such frequent mono / stereo conversion will be used.

In this case, depending on each application, mono / stereo may be determined and fixed in units of content or units of broadcast channels.

The cumulative determination in Table 1 above is a value arbitrarily defined in order to realize the above method, and the present invention will be described by taking the above definition as an example.

The new coefficients L, R, E, S, M to be used for statistical determination by the accumulation are exemplary values representing the update.

In the cumulative discrimination column of Table 1, L is left mono, R is right mono, E is Empty (Mute), S is Stereo, and M is Mid (= L + R) mono.

In order to determine whether mono / stereo is determined using the cumulative discrimination string of Table 1, after accumulating a predetermined time or more for each application, the coefficients having the largest value are compared and analyzed. Determines whether the current channel is mono / stereo.

Referring to the method of using the cumulative discrimination sequence of Table 1, if (DL, DX, DR) = (0, 0, 0), this means that there is no input signal or Mute (Empty) in stereo alone discrimination. In E, we define E = 3 and S = 1.

In the case of (DL, DX, DR) = (1, 1, 0), this means that the input signal is mono (L) or stereo, and it is determined as mono (Left) in single determination, but L = 1, S in cumulative determination. It is determined that = 1.

Now, as described above, the cumulative determination value is accumulated for the predetermined time, and the L / R, E, S, and M values are summed to determine whether the current channel is mono / stereo using the coefficient value having the largest value.

For example, if only the value of (DL, DX, DR) = (0, 0, 1) came in for 10 seconds, it would be R = 30, which would be determined as right mono.

Also, if (DL, DX, DR) is (0, 0, 0) (0, 0, 1) (0, 1, 0) (0, 1, 1) (1, 0, 0) (1, When 0, 1) (1, 1, 0) (1, 0, 1) is entered, the cumulative discrimination values are summed up with reference to Table 1 above, and (E = 3, S = 11, R = 4, M). = 3, L = 4).

Therefore, the largest value in the above is S = 11, and it is determined that the coefficient S represents the current channel, and the current channel is determined as S, that is, Stereo.

When the mono / stereo determination is completed by using the above-described method, the output channel generator 120 generates the output signals Lout and Rout by combining the input signals Lin and Rin according to the obtained value.

The above-described determination result is five types of L, R, E, S, and M. Even in the case of mono, the input / output relational expression as an example of generating an output signal in both Lout and Rout is as follows. This is shown below.

I / O relation Lout Rout L (Left mono) Lin Lin R (Right mono) Rin Rin E (Mute) 0 0 S (Stereo) Lin Rin M (Mid mono) (Lin + Rin) / 2 (Lin + Rin) / 2

Appears as

That is, when the cumulative determination result is S as described above, the output from the output channel generator 120 for two input audio signals Lin and Rin signals becomes Lout = Lin and Rout = Rin.

By using the method described above, the digital mono / stereo detector 45 transmits the determination result of the mono / stereo determiner 110 and the channel output from the output channel generator 120 to the digital signal processor 50. The digital audio signal is processed.

So far, the detailed operation of the internal configuration of the digital mono / stereo detector 45, which is the core of the present invention, has been described.

Hereinafter, referring to the accompanying drawings, a process of performing the above operation will be described with reference to FIG. 4. FIG. 4 is a flowchart illustrating a process performed by the digital mono / stereo detector 45 according to the present invention.

First, the digital mono / stereo detector 45 receives the A / D converted signal (step S10).

The received signal is input to the L / R correlation analyzer 100 to obtain an autocorrelation value and a cross-correlation value of the digital audio signal using Equation 1 or 2 (step S20).

After the correlation value is obtained, the mono / stereo decision unit 110 simplifies (DL, DX, DR) the binary values of 0 and 1 by the threshold value TL using the obtained correlation value as an input. S30 step)

Using the definition of the simplified (DL, DX, DR) values alone or cumulative discrimination method is determined whether the mono / stereo (S40).

By using the determined result, the output channel generator 120 generates an output channel by combining input signals (step S50).

The digital signal processor 50 now processes the digital audio signal by using the generated output channel and the mono / stereo determination result (step S60).

The audio signal received through the above-described steps is digitally processed.

Using the above-described digital audio processing apparatus and method, it is possible to determine whether mono / stereo is from the two channel digital audio signal coming into the input regardless of mono / stereo recognition in the analog processor.

In addition, by providing a function of discriminating mono / stereo using only the signal characteristics of two channels, it is possible to prevent malfunction of the system due to incorrect mono / stereo discrimination information.

In addition, when receiving the input signal of the two left and right channels and performing digital audio compression coding and storing the same or performing digital signal processing such as a sound field effect to reproduce with two speakers, the current input signal Knowing whether is stereo is beneficial in many ways.

In other words, by detecting the mistaken mono signal, the compression space may be doubled when performing the compression encoding or when the mono signal is stored compared to the stereo, and the sound field effect may be inserted. Even in this case, it is essential to know mono / stereo in applying a pseudo stereo technique.

For mono, the pseudo stereo technique should be used to insert the sound field effect, but if it is stereo, it is not necessary to use the pseudo stereo technique. The method of finding this is preferable.

In addition, according to the present invention, the degree of mono / stereo may be quantified to be used as basic information for genre analysis of input audio content.

The present invention is not limited to the above-described embodiments, and as can be seen in the appended claims, modifications can be made by those skilled in the art to which the invention pertains, and such modifications are within the scope of the present invention.

The effects of the digital audio signal processing apparatus and method according to the present invention described above are as follows.

According to the present invention, by determining the presence or absence of mono / stereo by using correlation characteristics of digital audio signals of two channels without prior information, it is possible to compensate for false mono / stereo determination in the analog processing unit, and the related information Even if it can not be obtained, there is an effect that can automatically determine whether the mono / stereo.

Claims (6)

After analog signal processing and A / D conversion, A digital mono / stereo detector for determining whether the converted audio channel is mono / stereo and outputting corresponding outputs; And a digital signal processing unit for receiving the output of the detection unit, processing the digital signal, and outputting the digital signal. The method of claim 1, wherein the digital mono / stereo detector, An L / R correlation analyzer for calculating and outputting an autocorrelation value and a cross correlation value for each channel of the input channel audio signal; A mono / stereo decision unit which finally determines whether the current channel is mono / stereo by using the output autocorrelation value and the cross correlation value; And an output channel generator for generating an output by combining the input channels according to the determination of the determination unit. The method of claim 2, And a determination result of the mono / stereo determination unit and an output of the output channel generator to the digital signal processor for use in digital signal processing. After analog signal processing and A / D conversion, A first step of obtaining an autocorrelation value and a cross-correlation value in a current channel to determine whether the converted signal is mono / stereo; A second step of determining whether mono / stereo is obtained using the obtained autocorrelation value and cross correlation value; And a third step of generating and transmitting an output signal by combining input signals according to the determination. The method of claim 4, wherein in the second step, And comparing the obtained autocorrelation value and cross-correlation value to 0 and 1 by comparing the threshold value set in the receiving apparatus, and then determining whether mono / stereo is used using the simplified value. Signal processing method. The method of claim 5, wherein If the correlation values are smaller than the threshold value set in the receiver, the simplification value is set to '0', and if the correlation values are larger than the threshold value set in the receiver, the simplification value is set to '1'. Digital audio signal processing method.

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