JPH0255431A - Information transmission equipment - Google Patents

Abstract

PURPOSE:To improve signal compression efficiency by providing a correlation coder with plural inputs and a correlation decoder decoding the inputs and using a delay device to set the delay of the plural input signals. CONSTITUTION:When two input signals are right and left channel signals of stereo signals, the correlation between the two signals is high. Then the mean value of the absolute value of the output of a subtractor 13 is expressed in equation I, where C is a component of correlation between the two signals after a delay by a delay device, and Id1, rd2 are respectively components without correlation. Then the delay when the mean value of the absolute value minimizing the result of equation I is obtained, the result is used as an optimum delay and the result is outputted from a correlation coder 1 as a 1 byte data. Moreover, the relation of equation II due to high correlation exists and the information lost by 4-bit coding is not so much different from the result of a conventional coding. On the other hand, since the output of the subtractor 13 is a small value, the information lost even by 1-bit coding is sufficiently suppressed small.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an information transmission device that compresses and transmits audio and image signals.

BACKGROUND OF THE INVENTION In recent years, information transmission devices, such as video telephones, have used signal compression technology to transmit higher quality audio and images using limited transmission line capacity. Many of the signal compression techniques used for this purpose use temporal autocorrelation of a single signal.

An example of the above-mentioned conventional information transmission device will be described below with reference to the drawings.

FIGS. 4 and 5 respectively show the configurations of an encoding device and a decoding device of a conventional information transmission device. In FIG. 4, 111 is a delay device, 112 is a subtracter, and 113 is a quantizer, which are connected as shown.

The operation of the encoding device of the information transmission device configured as described above will be described below.

First, an input signal to be encoded is given a fixed time delay by a delay device 111, and then a difference from itself is taken by a subtracter 113. This operation is interpreted as removing the autocorrelation component of the input signal and extracting the residual. Quantizer 11
3 encodes this residual, and in a simple case, the residual signal is requantized to, for example, 4 bits. The information truncated by the encoder 113 cannot be recovered by the decoder described below.

The output of quantizer 113 is 4 bits per sample of the input signal.

When the input signal is X, the transfer function of the delay device 111 is D, the information lost in the quantizer 113 is N, and the output signal is Y, the following equation holds true.

Y= (1-D)X-N (1)
This encoded signal is decoded by a decoding device shown in FIG.

In FIG. 5, 121 is a decoder, 122 is an adder,
123 is a delay device, and the output of the delay device 123 is sent to the adder 1.
22.

The operation of the decoding device of the information transmission device configured as described above will be described below.

The encoded signal is first decoded by a decoder 121. In this simplest example, nothing is done. When a complex quantizer such as a vector quantizer is used, the decoder 121 decodes the signal into the original difference signal using a codebook.

This difference signal is added to the output of the delay device 123 by the adder 122, and becomes the input to the delay device 123 again, thereby reproducing the original signal as shown in the following equation.

The transfer function of the delay device 123 is assumed to be D.

X"-Y/(1-D) -((1-D)X-N)/ (1-D)=X-N/ (
1-D) (2) If the rate of change of the input signal The encoded information N can be kept sufficiently small and the encoded signal is compressed.

In the decoding device, the lost information N is multiplied by 1/(1-D). If this effect becomes a problem, the information N lost in the quantizer 113 is feedback added to the input of the quantizer 113 to cancel out the effect in the decoding device.

(For example, "Digital Signal Processing of Images," Nikkan Kogyo Shimbun, p. 171).

Problems to be Solved by the Invention However, if the above configuration is applied as is to a case where there are multiple input signals, and each human input signal is individually encoded and decoded, the data amount of the encoded output signal will be Since the number of inputs is multiplied by 1 (n), the compression efficiency is poor.

In view of the above problems, the present invention provides an information transmission device that efficiently compresses and encodes a plurality of input signals.

Means for Solving the Problems In order to solve the above problems, the information transmission device of the present invention inputs a plurality of signals simultaneously, and extracts correlated components and uncorrelated components from the plurality of input signals. , a correlation encoding device that encodes each of these and outputs a coded signal, and a correlation decoding device that inputs the output signal of the correlation encoding device, decodes each of these, and then decodes it into the original signal. The above-mentioned correlation encoding device comprises: a delay device that delays a plurality of human input signals for an arbitrary time; an adder and a subtracter that create a sum signal and a difference signal of the output signals of the delay device; The delay device is provided with an encoder that encodes each output signal, and the delay device sets the delay amount so that the average value of the absolute values of the subtracter outputs obtained by changing the delay amount is the smallest. It is equipped with the ability to output.

Effect: With the above-described configuration, the present invention utilizes the correlation between a plurality of input signals, which has not been used in the past, to compress encoded signals and improve the information transmission rate.

Embodiment Hereinafter, an information transmission apparatus according to an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 shows the configuration of an information transmission device in an embodiment of the present invention. In FIG. 1, 1 is a correlation encoding device, and 2 is a correlation decoding device.

FIG. 2 shows a more detailed configuration of the correlation encoding device, and is for a case where there are two input signals. In FIG. 2, 11 is a delay device, 12 is an adder, 13 is a subtracter, 14 is a first encoder, and 15 is a second encoder. The outputs thereof are input to an adder 12 and a subtracter 13, and the respective outputs are applied to a first encoder and a second encoder.

The operation of the encoding device of the information transmission device configured as described above will be described below with reference to FIGS. 1 and 2.

If the two input signals are right and left channel signals of a stereo signal, the correlation between the two signals is high. 2
Components with correlation between signals are C1 and components without correlation are 1. If r is 2 signals, R is L=C+1...(3) R=
It can be expressed as C+r...(4).

Furthermore, when the delay device 11 adds different delays D1D2 to the two signals R, the delay device output signals L and R become dl d2 L, , = LD, ...... (5) Rd
□-R-D2 ......(6), and after adding the delay, if the component with correlation between the two signals is C1 and the component without correlation is 'dlrd2, then the two signals Ldl+Ld2 are , Ld I =C+'d +
・・・・・・(7) R82=C+r
, 2 °°°°” (8).

Adder 1 when inputting signals with different delays
2 and the output of the subtracter 13 are respectively Ld1+Rd2-
2C+1d, +rd2 ・・・・・・(9) Ldl
Ld2-1dl rd2..."" becomes OI.

The average value of the absolute values of the output of the above subtracter is I dr
r a 2 -=ill), and for the input signal R, calculate the average value of the above absolute values with D, , D2 as variables, and obtain the delay value when the average value of the minimum absolute values is obtained. is set as the optimum delay amount and output as 1-byte data from the correlation encoder.

Also, since the correlation is high, C〉〉ld工、rd□・・・・・・02
), and the output of the adder 12 is (2C+Id□+",2)
The information it has is almost only the component C that has a correlation between the two input signals, and this is processed, for example, by a 4-bit encoder 13 having the same configuration as the quantizer 113 shown in FIG. The information N1 that is lost even when encoded is almost the same as in the conventional example.

On the other hand, the output (ld I rd2 ) of the subtracter 13 is
Although the components have no correlation, they have small values, so even if the second encoder 15 encodes with a smaller word length, for example, 1 bit, the information N2 lost can be sufficiently small (reduced).

Therefore, if the total number of samples is 100, the data amount of the entire encoded output signal is 4+1+(8/
100) = 5.08 bits, which enables efficient compression encoding.

Next, decoding will be explained.

FIG. 3 shows the detailed configuration of the correlation decoding device.
21 is a first decoder, 22 is a second decoder, 23 is an adder, 24 is a subtracter, 25, 26 is a 1/2 multiplier, 27 is a delay device, and The output of the decoder 2 is sent to the adder 23. fJIi multiplier 24, its output is applied to multiplier 25, 26, and its output is applied to delay device 27.

The operation of the correlation decoding device configured as described above will be described below.

The outputs of the correlation coding device 1 are applied to first and second decoders 21, 22, respectively. In this embodiment, the decoders 21 and 22 do not process anything. Its output 2C+1. , +rd2-N.

Idl rd2 N2 is the adder 23 . is added to the subtracter 24, and (2C+1
d l +rd 2 −N1 )+(I d , +r
d2-N2)=2 (C+ld,)-(N,+
N2)...03)(2C+]d, +rd2-N
, )-(1,,-rd2-N2)=2 (C+ rd2
) (N1N2) ・==・O'fJ,
It is halved by the multiplier 25.26, (C++d,) - (N
, 10N2)/2=Ld□-(N, →-N2)/2
...00 (c10rd2) (N, -N2
)/2=Rd2- (N1-N2)/2 ・Old・
・When the signal becomes 0ω, the delayed signal is decoded, and the delay amount difference output from the correlation encoding device 1 is set in the delay device 27 so that it is reversed in L and R. The outputs are respectively delayed and the original signal LR is decoded.

Lost information (N, +N2)/2. (N, -N2)/
2. Please lead well.

As described above, according to this embodiment, there is provided a correlation encoding device and a correlation decoding device that perform encoding and decoding using the correlation of a plurality of input signals, and the correlation encoding device encodes and decodes a plurality of input signals by using correlations. a delay device that delays an arbitrary time; an adder and a subtracter that create a sum signal and a difference signal of the output signals of the delay device; and first and second codes that encode the output signals of the adder and the subtracter, respectively. The delay device sets the delay amount so that the average value of the absolute values of the subtracter outputs obtained by changing the delay amount is the smallest, and outputs the delay amount, thereby changing the input signal. In case 2, an efficient encoder can be realized by utilizing the correlation between input signals.

Note that in this embodiment, the first and second encoders 14.
15 is a 4.1-bit quantizer, but a general encoder may be used, for example, the entire encoding device shown in FIG. 4 may be used. In that case, the first and second decoders 21,22 also correspondingly use the entire decoding device shown in FIG.

Further, in this embodiment, adders and subtracters are used to extract correlated components and uncorrelated components between input signals, but any device may be used as long as it performs the same function.

In addition, in this embodiment, the delay amount output from the delay device is 1
Although the amount of data is in bytes, -C may be in b bits instead of in hide units. Furthermore, by inserting a delay into each input signal, the input signals can be relatively advanced.

Further, although the present embodiment shows the case where the number of inputs is two, the encoding efficiency can generally be improved in the same manner even with n inputs.

Effects of the Invention As described above, the present invention inputs a plurality of signals simultaneously, extracts correlated components and uncorrelated components from the plurality of input signals, encodes each of these components, and generates an encoded signal. The correlation encoding device includes a correlation encoding device that outputs an output signal, and a correlation decoding device that inputs an output signal of the correlation encoding device, decodes each signal, and then decodes it into an original signal. A delay device that delays a human signal by an arbitrary amount of time;
An adder and a subtracter that generate a sum signal and a difference signal of the output signals of the delay device, and an encoder that encodes the output signals of the adder and the subtracter, respectively, and the delay device changes the amount of delay. By setting the delay amount so that the average value of the absolute values of the subtracter output obtained by can.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of an information transmission device according to an embodiment of the present invention, Fig. 2 is a block diagram of a correlation encoding device, Fig. 3 is a block diagram of a correlation decoding device, and Fig. 4 is a block diagram of a conventional information transmission device. FIG. 5 is a block diagram of the encoding device of the apparatus, and FIG. 5 is also a block diagram of the decoding device. 1... Correlation encoding device, 2... Correlation decoding device, 11.27... Delay device, 12.23
...Adder, 13.24...Subtractor,
14...First encoder, 15...Second encoder, 21...First decoder, 22
...Second decoder, 25.26...
Multiplier, ■ 13...Quantizer.

Claims (2)

[Claims] (1) inputting multiple signals simultaneously and extracting correlated components and uncorrelated components from the multiple input signals;
It includes a correlation encoding device that encodes each of these and outputs a coded signal, and a correlation decoding device that inputs the output signal of the correlation encoding device, decodes each signal, and decodes it into the original signal. , the above-mentioned correlation encoding device includes a delay device that delays a plurality of input signals for an arbitrary time, an adder and a subtracter that create a sum signal and a difference signal of the output signals of the delay device, and outputs of the adder and subtracter. an encoder that encodes each signal, and the delay device sets the delay amount so that the average value of the absolute values of the subtracter outputs obtained by changing the delay amount is the smallest, and An information transmission device characterized by outputting information. (2) The correlation decoding device decodes the original signal using a decoder that decodes each encoded signal output from the correlation encoding device, and the delay amount, sum, and difference of the obtained decoded signals. 2. The information transmission device according to claim 1, comprising an adder and a subtracter, a delay device, and a multiplier.