JPH08162968A - Information encoding method and apparatus, information decoding method and apparatus, and recording medium - Google Patents

Abstract

(57) Abstract: Mixed noise generated by premix processing and dematrix processing is effectively reduced. SOLUTION: Premix means 2 for mixing independently coded independent channel signals and non-independent channel signals not independently coded, and coding for coding the obtained mixed channel signal and independent channel signal. Means 3
A decoding means 4 for decoding the mixed channel signal and the independent channel signal after encoding, and a dematrix means 5 for generating a non-independent channel signal from the mixed channel signal and the independent channel signal after decoding, Error signal detecting means 6 for generating a differential signal between the generated non-independent channel signal and the non-independent channel signal before mixing, error signal encoding means 6 for encoding the differential signal, and independent channel signal after encoding. And a multiplexing means 8 for generating a code string signal from the mixed channel signal and the difference signal.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention compresses and decodes a plurality of channels of signals used in so-called multi-channel sound and sound systems such as motion picture film projection systems, video tape recorders and video disc players. The present invention relates to an information encoding method and device, an information decoding method and device, and a recording medium on which a signal formed by the information encoding method and device is recorded.

[0002]

2. Description of the Related Art In a motion picture film in which a plurality of channels of audio or voice signals are recorded, a left channel (L), a center channel (C), a right channel (R) and a surround left channel (SL) are used as the plurality of channels. ), And a surround right channel (SR) 5-channel digital audio signal may be handled.

Here, for recording the signals of these respective channels, for example, on the recording medium as they are or transmitting them to the communication path, since a large capacity recording medium or communication path is required,
Usually, these signals are compressed and encoded with high efficiency and recorded or transmitted. There are various techniques and apparatuses for high-efficiency coding of signals such as audio or voice. For example, an audio signal in the time domain is divided into blocks for each unit time, and the time axis signal for each block is a frequency axis. There is a so-called transform coding system, which is a blocking frequency band division system that transforms (orthogonal transforms) the above signal into a plurality of frequency bands and encodes each band.

Band division coding (sub-band coding), which is a non-blocking frequency band division method in which a time domain audio signal or the like is not divided into blocks for each unit time and is divided into a plurality of frequency bands for encoding A method can be mentioned. A high-efficiency coding method and device in which the above band-division coding and transform coding are combined is also considered. In this case, for example, after performing band-division by the band-division coding, A band signal is orthogonally transformed into a frequency domain signal, and coding is performed for each of the orthogonally transformed bands. The number of channels is usually used in a device that compresses and encodes or records or transmits the plurality of signals by using such an encoding method, or a device that decodes and reproduces or receives the plurality of compression-encoded signals. Minute encoding and decoding circuits are required. In the example of the above-mentioned motion picture film, an encoding circuit and a decoding circuit for 5 channels are required.

FIG. 6 shows the above five channels as the plurality of channels.
Channels (L), (SL), (C), (SR),
The configuration of an encoding device that independently encodes the (R) digital audio signal for each channel is shown.

[0006] In FIG. 6, the input terminal 51 ₁ is inputted digital audio signal of the left channel (L), a digital audio signal of a surround left channel (SL) to the input terminal 51 _2, and so on terminal 51 the center channel signal (C) to _3, the signal of a surround right channel (SR) to the terminal 51 _4, the input terminal 51 ₅ is a signal of right channel (R) is input.

[0007] The digital audio signals of the plurality of channels, through each input terminal 51 ₁ to 51 ₅ corresponding to the respective channels, sent to the encoding circuit 52 ₁ to 52 ₅ provided in the similarly corresponding to respective channels To be Encoded signals by each encoding circuit 52 ₁ to 52 ₅ are sent to the codestring generating circuit 53.

The code string generating circuit 53 assembles coded signals of a plurality of channels into a code string for transmission or recording on a recording medium according to a predetermined format. The code string signal is output from the output terminal 54, recorded on a recording medium (not shown), or transmitted via a transmission path. The configuration of the decoding device for decoding the recorded or transmitted encoded signals of a plurality of channels is as shown in FIG.

In FIG. 7, the coded signal, which is the above-mentioned code string reproduced from the recording medium or transmitted through the transmission path, is supplied to the input terminal 61 and the code string separation circuit 62. To be done. The code string separation circuit 6
In 2, the supplied code string signal is separated into coded signals of each channel according to a predetermined format.
The coded signal of each channel is sent to the decoding circuit 63 ₁ to 63 ₅ provided corresponding to each channel.
For example, the encoded signal of the left channel is decoded by the decoding circuit 63 ₁ , the encoded signal of the surround left channel is decoded by the decoding circuit 63 ₂ , and so on. The decoded signal is decoded by the decoding circuit 63 ₃ , the surround right channel coded signal is decoded by the decoding circuit 63 ₄ , and the right channel coded signal is decoded by the decoding circuit 63 ₅ . It

[0010] Each channel decoded by these decoding circuits _{63 1 ~63 5 (L),} (SL), (C), (S
The R) and (R) digital audio signals are output from the corresponding output terminals 64 ₁ to 64 ₅ . Here, when decoding and reproducing a code string signal obtained by encoding signals of a plurality of channels as described above, the same number of reproducing devices such as speakers and amplifiers are required. In the above example, a playback device of 5 channels is required.

However, when a simplified reproducing apparatus is used, reproduction with a smaller number of reproducing channels than the original number of channels, for example, two channels may be required.

In this case, it is necessary to mix the reproduced signals of the respective channels decoded by the 5-channel decoding device of the above example into the two channels. This is realized, for example, by addition such as Expression (1) or Expression (2) shown below.

Lm = L + a * C + b * SL (1) Rm = R + a * C + b * SR (2) where Lm represents a mixed left channel (hereinafter referred to as a mixed left channel) Where Rm is a mixed right channel (hereinafter referred to as a mixed right channel), L is a left channel, R is a right channel, C is a center channel, SL is a surround left channel, and SR is a surround channel. It represents a light channel, and a and b represent mixing coefficients.

However, in this case, although only two channels have to be reproduced, the decoding device requires a decoding circuit for five channels. Therefore, the scale of the decoding device is the same as that of the 5-channel decoding device, and therefore cannot be easily realized.

Therefore, in order to easily reproduce a signal of two channels, a signal in which signals of other channels are mixed in advance is transmitted for two channels of the signal to be transmitted, and the second signal is transmitted.
A method is conceivable in which only the channel signal is decoded by the decoding device. Such a method of mixing the channel signals in advance is called a premix method.

For example, on the encoding device side, signals of each channel are formed by the following equations (3) to (7) and transmitted, but on the decoding device side, equation (3) is used. , Only the signals of the channels shown in equation (4) (that is, the mixed left channel and the mixed right channel) are decoded.

Lm = L + a * C + b * SL (3) Rm = R + a * C + b * SR (4) C (5) SL (6) SR (7) As a result, the decoding device can operate in the mixed left channel (L).
m) and a mixed write channel (Rm) for only two channels, the apparatus can be configured easily.

On the other hand, for example, when the signals of the left channel (L) and the right channel (R) are reproduced, the signals of the channels that are not sent independently are mixed channels (mixed left channel and mixed right channel).
By subtracting from the signal of, it is necessary to create. That is, the processing of subtracting the signal sent independently from the signal of the mixed channel is performed. This is called dematrix processing.

For example, in order to generate the signals of the left channel (L) and the right channel (R) from the signals of the above equations (3) to (7), the following equations (8) and (9) are used.
Is required.

L = Lm-a * C-b * SL (8) R = Rm-a * C-b * SR (9) FIG. 8 shows an encoding device for encoding the channel signal subjected to the premix processing. Shows the configuration of. In FIG. 8, the same reference numerals are given to the constituent elements having the same functions as those in FIG.

In FIG. 8, the encoding circuit 52 provided for, for example, the left channel in FIG. 6 is used.
_An adder circuit 72 ₁ is arranged in the preceding stage of ₁ . In the adder circuit 72 ₁ , the left channel signal input to the input terminal 51 ₁ and the surround left channel signal input to the input terminal 51 ₂ are multiplied by the coefficient b in the multiplication circuit 71 ₂ to obtain b The multiplied signal and the signal of the center channel input to the input terminal 51 ₃ are multiplied by the multiplication circuit 71 ₁
The signal a multiplied by a by being multiplied by the coefficient a is sent at, and these signals are mixed in the adder circuit 72 ₁ to form a mixed left channel (Lm) signal. The signals of the mixed left channel is sent to the encoding circuit 52 _1, the encoded signal by the encoding circuit 52 ₁ is sent to the codestring generating circuit 53.

Further, in FIG. 6, an adder circuit 72 ₂ is arranged in the preceding stage of the encoding circuit 52 ₅ provided for the write channel, for example. In the adder circuit 72 ₂ , the signal of the right channel input to the input terminal 51 ₅ and the signal of the surround right channel input to the input terminal 51 ₄ are multiplied by the coefficient b in the multiplier circuit 71 ₃ so that b The multiplied signal and the signal of the center channel input to the input terminal 51 ₃ are multiplied by the coefficient a in the multiplication circuit 71 ₁ , and the signal multiplied by a is sent,
These signals are mixed by the adder circuit 72 ₂ to form a mixed write channel (Rm) signal. Signals of the mixed right channel are sent to the encoding circuit 52 _5,
The signal encoded by the encoding circuit 52 ₅ is sent to the code string generation circuit 53.

[0023] Each signal of the surround left channel and the center channel and the surround right channels inputted to the input terminal 51 ₂ to 51 _4, after being encoded by the corresponding coding circuits 52 ₂ to 52 _4, the code sequence It is sent to the generation circuit 53.

[0024] In the code string generation circuit 53 to generate a code string of the predetermined format from the encoded signal by the encoder circuit 52 ₁ to 52 ₅ described above, the code sequence signal terminal 5
It is output from 4.

Next, FIG. 9 shows a decoding process for decoding and reproducing only the signals of the mixed left channel and the mixed right channel of two channels from the code string including the signals of the channels premixed in the configuration of FIG. 1 shows the configuration of a digitizing device. Note that, in FIG. 9, the same reference numerals are attached to the components having the same functions as those in FIG. 7.

In FIG. 9, the code string signal input to the input terminal 61 is extracted by the code string separation circuit 62 from only the signals of the mixed left channel and the mixed right channel, which are provided in correspondence with each other. Decoding circuit 6
Sent to 3 ₁ and 63 ₂ . The signal decoded by the decoding circuit 63 ₁ is output from the output terminal 64 ₁ as a mixed left channel (Lm) signal, and the decoding circuit 6
3 decoded signal by ₂ mixed right channel (R
m) signal is output from the output terminal 64 ₂ .

Next, FIG. 10 shows a configuration of a decoding apparatus for decoding the code string signal including the premixed channel and performing the dematrix processing in a non-premixed state. In FIG. 10, constituent elements having the same functions as those in FIG. 7 are designated by the same reference numerals.

In FIG. 10, the code string signal input to the input terminal 61 is coded by the code string separating circuit 62 in the mixed left channel, surround left channel, center channel, surround right channel and mixed right. Separated into channel signals.
The mixed left channel coded signal is decoded by the decoding circuit 63 ₁ , and similarly, the surround left channel coded signal is decoded by the decoding circuit 63 ₂ and the center channel code is decoded. The decoded signal is decoded by the decoding circuit 63 ₃ , the light surround channel coded signal is decoded by the decoding circuit 63 ₄ , and the mixed light channel coded signal is decoded by the decoding circuit 63 ₅ . To be done. The decoded surround left channel signal, center channel signal, and right surround channel signal are output from the corresponding output terminals 64 ₂ , 64 ₃ , 64 ₄ .

Here, an adder circuit 82 ₁ is arranged at the subsequent stage of the decoding circuit 63 ₁ for decoding the mixed left channel. The mixed left channel signal decoded by the decoding circuit 63 ₁ is input as an addition signal to the addition circuit 82 ₁ , and the decoding circuit 63 _{1 also} receives the mixed left channel signal.
The signal of the surround left channel decoded in ₂ is multiplied by a coefficient b in the multiplication circuit 81 ₂ to be a signal multiplied by b, and the signal of the center channel decoded in the decoding circuit 63 _{3 is} generated. Signal multiplication circuit 81
A signal multiplied by a by multiplying the coefficient a by ₁ is input as a subtraction signal. Therefore, the adder circuit 82 ₁
Then, a signal obtained by subtracting the surround left channel signal and the center channel signal from the mixed left channel signal, that is, a left channel signal is formed. The left channel signal is output from the output terminal 64 ₁ .

On the other hand, an adder circuit 82 ₂ is arranged at the subsequent stage of the decoding circuit 63 ₅ which decodes the mixed light channel. The decoding circuit 6 is provided in the addition circuit 82 _2.
The mixed light channel signal decoded in 3 ₅ is input as an addition signal, and the decoding circuit 63 ₄
The signal of the surround right channel, which has been decoded by, is multiplied by a coefficient b in the multiplication circuit 81 ₃ and multiplied by b as a subtraction signal, and the signal of the center channel, which is decoded by the decoding circuit 63 ₃ . Multiply circuit 81 ₁
The signal multiplied by a by multiplying by the coefficient a is input as a subtraction signal. Therefore, the adder circuit 82 ₂ forms a signal obtained by subtracting the surround write channel signal and the center channel signal from the mixed write channel signal, that is, a write channel signal. The signal of this light channel is output terminal 6
It is output from 4 ₅ .

The above system is based on the International Standards Organization (ISO: In
Established as a member of the ternatioal Organization for Standardization, a study organization for video coding for storage (M
PEG: Moving Picture Image Coding Experts Grou
p) MPEG2 audio standard (ISO / IE
This is the technique used in C 13818-3).

By the way, when the above-mentioned dematrix processing is performed, noise may increase in the signal reproduced by the dematrix processing as compared with the original signal. This noise is tentatively called mixed noise.

For example, if the signal level of the left channel (L) in the equation (3) is the other channel (a * C),
It is assumed that the signal level is extremely smaller than the signal level of (b * SL). In this case, when a signal in which signals of other channels are mixed is encoded by a high-efficiency encoding method and then decoded and subjected to dematrix processing, quantization noise of other channels becomes dominant, and equation (8) ) The left channel signal obtained by the calculation of 1) is output with the quantization noise of another channel superimposed.

As described above, an example of the case where the noise increases is
This will be described using the waveform of each channel shown in FIG.

FIG. 11A shows the input terminal 51 of FIG.
Each channel input to the _{1 ~51 5 (L), (} R),
The signal waveform examples of (C), (SL), and (SR) are shown. Also, the (b) of FIG. 11, the input signals of the respective channels shown in FIG. 11 (a) after the pre-mixing process in the configuration of FIG. 8, each encoding circuit 52 ₁ to 52 ₅ The signal waveform of the channel is shown. That is, FIG.
In (b), Lm is the signal waveform of the mixed left channel, Rm is the signal waveform of the mixed right channel,
The signal waveforms of the other three channels (C), (SL) and (SR) are the same as those in (a) of FIG. These FIG.
The signal of each channel shown in (b) of FIG. 3 corresponds to a signal on the recording medium or the transmission path. Further, in (c) of FIG.
The signals of the respective channels shown in (b) of FIG. 11, sent to the configuration shown in FIG. 10, and decoded by the decoding circuit 63 ₁ to 63 ₅ corresponding to each channel, yet de of the Figure 10 Each channel (L), (R), (C), (SL), (SR) obtained by the matrix processing configuration
2 shows an example of the signal waveform (that is, an example of the waveform of the signal output from the output terminals 64 ₁ to 64 ₅ ).

In FIG. 11, comparing the signal waveform of each channel in FIG. 11A with the signal waveform of each channel in FIG. 11C, the decoded and dematrixed signal is obtained. The left channel (L) signal and the right channel (R) signal of FIG. 11C include signal components that were not present in the respective channel signals of FIG. 11A at the time of encoding. You can see that This is the mixed noise generated by the dematrix processing,
As described above, the noise is generated by superimposing the quantization noise of other channels.

It is known that such a phenomenon of noise generation remarkably appears in a signal of a channel having a small signal level.

Therefore, in order to solve this problem, a method has been considered in which each channel is selectively switched so that a signal of a channel having a low signal level is independently encoded.

Another method is a so-called simulcast method in which the number of channels is increased and all independent channel signals and mixed channel signals are encoded.

FIG. 12 shows a coding apparatus for coding a signal by the simulcast method. Note that, also in FIG. 12, constituent elements having the same functions as those in FIGS. 6 and 8 are designated by the same reference numerals.

In FIG. 12, the left channel signal supplied to the input terminal 51 ₁ is the encoding circuit 52 ₂
To the adder circuit 72 ₁ . The signal encoded by the encoding circuit 52 ₂ is sent to the code string generation circuit 53.

On the other hand, in the adder circuit 72 ₁ , the left channel signal from the input terminal 51 ₁ and the surround left channel signal input to the input terminal 51 ₂ are multiplied by the coefficient b in the multiplication circuit 71 _2. As a result, the signal multiplied by b and the signal of the center channel input to the input terminal 51 ₃ are multiplied by the coefficient a in the multiplication circuit 71 ₁ , and the signal multiplied by a is sent. The signals are mixed in the adder circuit 72 ₁ to form a mixed left channel (Lm) signal. This mixed left channel signal is sent to the coding circuit 52 ₁ , where it is coded and then sent to the code example generation circuit 53.

The write channel signal supplied to the input terminal 51 ₅ is supplied to the encoding circuit 52 ₆ and the addition circuit 72 ₂
Sent to. The signal encoded by the encoding circuit 52 ₂ is sent to the code string generation circuit 53.

On the other hand, the adder circuit 72 ₂ multiplies the write channel signal from the input terminal 51 ₅ and the surround write channel signal input to the input terminal 51 ₄ by the coefficient b in the multiplication circuit 71 _3. As a result, the signal multiplied by b and the signal of the center channel input to the input terminal 51 ₃ are multiplied by the coefficient a in the multiplication circuit 71 ₁ , and the signal multiplied by a is sent. The signals are mixed in the adder circuit 72 ₂ to form a mixed light channel (Rm) signal. Signals of the mixed right channel are sent to the encoding circuit 52 _7, after being here encoded and sent to the code example generation circuit 53.

[0045] Further, the signals of the surround left channel and center channel and the surround right channel input to the input terminal 51 ₂ to 51 _4, after being encoded by the encoding circuit 52 _{3-52 5} corresponding, It is sent to the code string generation circuit 53.

[0046] In the code string generation circuit 53 to generate a code string of the predetermined format from the encoded signal by the encoder circuit 52 ₁ to 52 ₇ described above, the code sequence signal terminal 5
It is output from 4.

As described above, in the encoding device of FIG. 12, the signals of the mixed left channel and the mixed right channel are
It is coded together with other independent channel signals.

A simple decoding device for reproducing only signals of two mixed channels (mixed left channel and mixed right channel) corresponding to the encoding device of FIG. 12 is the same as that of FIG. To do.

The configuration of the decoding device for decoding the coded signal of the simulcast method is the same as that shown in FIG. 7 and its explanation is omitted. That is, in the configuration of FIG. 7, even if the code string signal obtained in the configuration of FIG. 12 is supplied through the input terminal 61, the mixed left channel and mixed right channel signals are not decoded. become.

[0050]

By the way, as a method for reducing the mixed noise generated when the signals of the mixed channels are dematrixed, the above-mentioned method of switching the contents of the independent channels to be encoded is used. If the mixed signals are low in level, the effect is obtained. However, in the case of a signal having a high signal level and no correlation with other channels, mixed noise may be heard. When this method is implemented, for example, operations such as signal level detection and channel switching become complicated, the circuit configuration becomes large-scale, and a switching control signal indicating which channel is selected is also decoded. It will have to be transmitted to the processing device side.

As a method for reducing the mixed noise generated when the signals of the mixed channels are dematrixed, as described above, the number of channels is increased,
When a method of encoding signals of all independent channels and mixed channels is used, there is a problem in that sound quality deterioration occurs due to insufficient number of bits as the number of channels increases. In order to prevent this sound quality deterioration, the number of bits must be increased, which is unsuitable for a recording medium with a limited amount of recorded information.

Therefore, the present invention has been made in view of such a situation, and an information coding method and an information coding method capable of effectively reducing the mixed noise generated when the signals of the mixed channels are subjected to the dematrix processing. An object is to provide an apparatus, an information decoding method and apparatus, and a recording medium.

[0053]

In the information coding method and apparatus of the present invention, independent channel signals that are independently coded and non-independent channel signals that are not independently coded are mixed and mixed. Channel signals are generated, and then these signals are encoded and then decoded to generate non-independent channel signals, and the difference signal between the generated non-independent channel signal and the non-independent channel signal before mixing. , And a code string signal is generated from the coded independent channel signal, the mixed channel signal, and the differential signal.

Further, in the information decoding method and apparatus of the present invention, the coded signal obtained by the information coding method and apparatus of the present invention is the coded independent channel signal and mixed channel signal, respectively. And a differential signal are separated, each is decoded, a non-independent channel signal is generated from the decoded independent channel signal and mixed channel signal, and the generated non-independent channel signal and differential signal are generated. The above-mentioned problem is solved by adding

Further, the recording medium of the present invention is one in which the code string signal generated by the information encoding method and apparatus of the present invention is recorded.

That is, according to the present invention, at the time of encoding, in addition to the independent channel signal and the mixed channel signal, the non-independent channel signal obtained by dematrixing the mixed channel signal and the non-independent non-independent signal before mixing. A non-independent channel obtained by dematrixing the difference signal from the mixed channel signal at the time of providing a channel composed of a differential signal from the channel signal, encoding these signals to generate a code string signal, and at the time of decoding By adding to the signal of, the deterioration due to the mixed noise is prevented. Since this difference signal is due to the quantization noise component of the mixed channel signal, the number of bits required for encoding can be smaller than that in the case of encoding the signals of the independent channels as they are.

On the decoding side, if the above-mentioned differential signal is not decoded, it has the same structure as a conventional decoding device that performs dematrix processing, and therefore it can be made compatible with the conventional decoding device. Further, this method has a feature that it can be used in combination with the method of switching the contents of the channel to be encoded, which is shown in the conventional example. As described above, by using the present invention, it is possible to realize higher coding efficiency as compared with the conventional method.

[0058]

BEST MODE FOR CARRYING OUT THE INVENTION Preferred embodiments of the present invention will be described below with reference to the drawings.

First, the basic configuration of an encoding apparatus to which the information encoding method of the present invention is applied will be briefly described with reference to FIG.

In FIG. 1, a signal having signals of a plurality of channels is supplied to the input terminal 1 as an input signal. This input signal is sent to the premix means 2 and the error signal detection means 6.

In the premix means 2, the input terminal 1
A mixed channel signal is generated from a plurality of channel signals input via the and is sent to the encoding means 3 together with other independently encoded multiple channel signals.

The encoding means 3 encodes a plurality of channel signals including the mixed channel signal sent from the premix means 2 and the encoded signal obtained by this encoding is decoded by the multiplexing means 8 and the decoding means 8. Send to means 4.

In the decoding means 4, the encoding means 3 is used.
The coded signals of a plurality of channels including the mixed channel signal supplied from are decoded, and the signals obtained by this decoding are sent to the dematrix means 5.

The dematrix means 5 performs dematrix processing on the decoded signals of a plurality of channels including the mixed channel signals supplied from the decoding means 4, and produces a multichannel signal by the dematrix processing. The dematrixed multi-channel signals are sent to the error signal detecting means 6.

In the error signal detecting means 6, an error signal which is a difference signal is calculated from the dematrixed plural channel signals supplied from the dematrixing means 5 and the plural channel signals supplied from the input terminal 1. It is detected and sent to the error signal encoding means 7 as a channel error signal. The error signal coding means 7 codes the channel error signal from the error signal detecting means 6 and sends the coded signal of the channel error signal obtained by this coding to the multiplexing means 8.

The multiplexing means 8 multiplexes the coded signal from the coding means 3 and the coded signal from the error signal coding means 7 to generate a code string signal of a predetermined format,
This code string signal is output via the output terminal 9.

Next, the basic configuration of the decoding apparatus to which the information decoding method of the present invention is applied will be briefly described with reference to FIG.

In FIG. 2, a plurality of channels of code string signals including mixed channel signals and channel error signals encoded and multiplexed by the encoder of FIG. 1 are input to the input terminal 11. .

The code string signal input from the input terminal 11 is sent to the demultiplexing means 12. The demultiplexing means 12 demultiplexes the coded sequence signal of a plurality of channels including the mixed channel signal and the channel error signal, and decodes the obtained coded signal of each channel. Send to means 13.

The decoding means 13 decodes the coded signal of each channel. Among the signals obtained by this decoding, the channel error signal is sent to the error correction means 15, and the signals of a plurality of channels including the mixed channel are sent to the dematrix means 14. The dematrix means 14 dematrixes the signals of the plurality of channels including the decoded mixed channels, and sends the dematrixed signals of the plurality of channels to the error correction means 15.

The error correcting means 15 corrects the dematrixed channel signal from the dematrixing means 14 on the basis of the channel error signal from the decoding means 13. The error-corrected signals of a plurality of channels are output via the output terminal 16.

Next, referring to FIGS. 3 and 4, the basic configuration of FIGS. 1 and 2 is divided into a plurality of channels including the left channel, the surround left channel, the center channel, the surround right channel, and the right channel. Specific configurations of the encoding device and the decoding device when applied to a signal will be described below.

FIG. 3 shows a concrete example of the configuration of a coding device for coding a 5-channel signal.

[0074] In FIG. 3, the input terminal 21 ₁ is an audio signal of the left channel (L) is supplied, an input terminal 21 ₂ F surround left channel (SL)
Of the audio signal, the audio signal of the center channel to the input terminal 21 ₃ (C) is, to the input terminal 21 ₄ audio signals of the surround right channel (SR) is, to the input terminal 21 ₅ is the right channel (R) An audio signal is provided. Each of these input terminals 21 _1-2
1 ₅ corresponds to the input terminal 1 in FIG.

The left channel signal supplied to the input terminal 21 ₁ is added to the adding circuit 23 ₁ as an addition signal.
It is also sent as a subtraction signal to the adder circuit 28 ₁ described later. The adder circuit 23 ₁ also receives the surround left channel signal input to the input terminal 21 ₂ from the multiplier circuit 2 1.
The signal multiplied by b by multiplying the coefficient b by 2 ₂ and the signal obtained by multiplying the signal of the center channel input to the input terminal 21 ₃ by the coefficient a by the multiplication circuit 22 ₁ are multiplied by a. Are sent, and these signals are mixed in the adder circuit 23 ₁ to form a mixed left channel (Lm) signal.

The write channel signal supplied to the input terminal 21 ₅ is added as an addition signal by the addition circuit 23.
To _2, also fed to the adder circuit 28 ₂ to be described later as a subtraction signal. To the addition circuit 23 ₂ is also a b times the signal by the signal of a surround right channel input to the input terminal 21 ₄ is multiplied by the coefficient b by the multiplication circuit 22 ₃ is input to the input terminal 21 ₃ The signal of the center channel is multiplied by the coefficient a in the multiplication circuit 22 ₁ and the signal multiplied by a is sent, and these signals are mixed in the addition circuit 23 ₂ and mixed in the right channel (Rm) signal. Is formed.

The signal of the mixed left channel (Lm) formed as described above is sent to the encoding circuit 24 ₁ .
The mixed light channel (Rm) signal is encoded by the encoding circuit 24.
Sent to ₅ . Further, the respective signals of the surround left channel, the center channel, and the surround right channel input to the input terminals 21 _{2 to} 21 ₄ correspond to the encoding circuits 24 _{3 to} 24 as independent channel signals which are independently encoded. Sent to ₅ . These encoding circuits 24 _{1 to} 24 ₅ encode the supplied signals, respectively. As described above, in the configuration of FIG. 3, the configuration for forming the mixed channel signal corresponds to the premix unit 2 of FIG. 1, and each of the encoding circuits 24 _{1 to} 24 ₅ performs the encoding of FIG. Corresponding to the means 3, the left channel signal and the right channel signal are non-independent channel signals that are not independently encoded.

[0078] encoded signal from each encoder 24 _{1-24 5,} together are sent to decoding circuits 25 ₁ to 25 ₅ are provided corresponding, also sent to the codestring generating circuit 30 . The decoding circuits 25 _{1 to} 25 ₅ correspond to the decoding means 4 of FIG. 1, and the code example generation circuit 30 corresponds to the multiplexing means 8 of FIG.

Among the signals decoded by the decoding circuits 25 _{1 to} 25 ₅ , the mixed left channel signal is sent to the addition circuit 27 ₁ as an addition signal. This adder circuit 2
7 ₁ also includes a signal obtained by multiplying the surround left channel signal decoded by the decoding circuit 25 ₂ by a coefficient b by a multiplication circuit 26 ₂ by a factor of b, which is a subtraction signal. A signal obtained by multiplying the center channel signal decoded in 25 ₃ by a coefficient a in the multiplication circuit 26 ₁ and multiplied by a is input as a subtraction signal. Therefore, the adder circuit 27 ₁ forms a signal obtained by subtracting the surround left channel signal and the center channel signal from the mixed left channel signal, that is, a left channel signal including mixed noise. The left channel signal containing the mixed noise is sent to the adder circuit 28 ₁ as an added signal.

On the other hand, of the signals decoded by the decoding circuits 25 _{1 to} 25 ₅ , the mixed light channel signal is sent to the addition circuit 27 ₂ as an addition signal. The adder circuit 27 ₂ also multiplies the surround right channel signal decoded by the decoding circuit 25 ₄ by the multiplication circuit 2 2.
The signal multiplied by b by multiplying the coefficient b by 6 ₃ is used as a subtraction signal, and the center channel signal decoded by the decoding circuit 25 _{3 is} further multiplied by the coefficient a by the multiplication circuit 26 _1.
A signal multiplied by a by multiplying by is input as a subtraction signal. Therefore, the adder circuit 27 ₂ forms a signal obtained by subtracting the signal of the surround light channel and the signal of the center channel from the signal of the mixed light channel, that is, a signal of the light channel including mixed noise. The light channel signal containing the mixed noise is sent as an addition signal to the addition circuit 28 ₂ .

The left channel signal containing the mixed noise and the configuration for generating the right channel signal containing the mixed noise also correspond to the dematrix means 5 of FIG.

Further, the adding circuits 28 ₁ and 28 ₂ correspond to the error signal detecting means 6 of FIG.
_{In 1} , the difference between the unmixed left channel signal from the input terminal 21 ₁ and the left channel signal containing mixed noise from the adder circuit 27 ₁ is obtained, and in the adder circuit 28 ₂ , the input terminal is The difference between the unmixed light channel signal from 21 ₅ and the light channel signal containing mixed noise from the adder circuit 27 ₂ is obtained. Each difference signal from the adder circuit 28 ₁ and 28 _2, as the channel error signals Le and Re, respectively, are sent to the corresponding encoding circuits 29 ₁ and 29 _2.

These coding circuits 29 ₁ and 29 ₂ correspond to the error signal coding means 7 of FIG. 1, code the channel signal errors respectively supplied, and send them to the code string generation circuit 30.

In the code string generating circuit 30 corresponding to the multiplexing means 8 of FIG. 1, the signals of the respective channels coded by the above-mentioned coding circuits 24 _{1 to} 24 ₅ and the coding circuits 29 ₁ and 29. _The channel error signal encoded in ₂ is assembled into a code string for transmission or recording on a recording medium according to a predetermined format, and the code string signal is output via a terminal 31.

The code string signal output from the terminal 31 is recorded or transmitted to a predetermined transmission path. For example, when recording is performed, the code string signal is sent to the recording device 32. This recording device 32 has an error correction code addition circuit, a modulation circuit, etc. inside, and a code string signal processed by the error correction code addition circuit, the modulation circuit, etc. with respect to, for example, an optical disk 33 as an example of a recording medium. To record. A read-only ROM disk such as a so-called compact disk is manufactured as a master disk as a recording medium, and a writable RAM disk such as a magneto-optical disk is directly written with a code string.

Since the simple decoding device for reproducing only the mixed channel signals of the two channels which are premixed from the encoded signals of the plural channels as described above has the same configuration as that of FIG. The description is omitted.

On the other hand, as a concrete configuration of the decoding apparatus of the present invention shown in FIG. 2, the decoding is performed by dematrixing the coded signals of the plurality of channels into a non-premixed state for decoding. The device is as shown in FIG.

In FIG. 4, the code string signal reproduced from the recording medium or transmitted through the transmission path is supplied to the code string separation circuit 42 through the input terminal 41. The code string separation circuit 42 separates the supplied code string signal into a coded signal for each channel according to a predetermined format. This code string separation circuit 42 corresponds to the demultiplexing means 12 of FIG.

[0089] encoded signal of each channel demultiplexed by the code string separating circuit 42 is sent to the decoding circuit 43 ₁ to 43 _7, which is provided corresponding to each channel,
Each is decrypted. For example, the decoding circuit 43 ₁ decodes the coded signal of the channel error signal Le generated from the left channel including the mixed noise,
The decoding circuit 43 ₂ decodes the encoded signal of the left channel, and similarly, in the decoding circuit 43 ₃ the encoded signal of the surround left channel is decoded by the decoding circuit 43 2.
_{In 4} , the center channel encoded signal, the decoding circuit 43 _{5 includes} a surround right channel encoded signal, the decoding circuit 43 _{6 includes} a right channel encoded signal, and the decoding circuit 43 ₇ includes the mixed noise. Channel error signal Re generated from the read light channel
The encoded signals of are decoded respectively. These decoding circuits 43 ₁ to 43 ₇ correspond to the decoding means 13 in FIG.

Among the signals decoded by the decoding circuits 43 ₁ to 43 ₇ , the mixed left channel signal from the decoding circuit 43 ₂ is sent to the adding circuit 45 ₁ as an addition signal. The adder circuit 45 ₁ also multiplies the surround left channel signal decoded by the decoding circuit 43 ₃ by a coefficient b by a multiplication circuit 44 ₂ to obtain b.
The multiplied signal is used as a subtraction signal, and further, the decoding circuit 43
A signal obtained by multiplying the center channel signal decoded in ₄ by a coefficient a in a multiplication circuit 44 ₁ and multiplied by a is input as a subtraction signal. Therefore, the adder circuit 45 ₁ forms a signal obtained by subtracting the surround left channel signal and the center channel signal from the mixed left channel signal, that is, a left channel signal including mixed noise. The left channel signal containing the mixed noise is added by the adder circuit 46 ₁
Sent as an addition signal.

On the other hand, of the signals decoded by the decoding circuits 43 ₁ to 43 ₇ , the mixed light channel signal from the decoding circuit 43 ₆ is added as an addition signal by the addition circuit 45.
Sent to ₂ . Also in this adding circuit 45 _2, signal b times by multiplying the coefficient b of the signal of a surround right channel, which is decoded by the decoding circuit 43 ₅ by the multiplication circuit 44 ₃ as a subtraction signal, and further, A signal obtained by multiplying the center channel signal decoded by the decoding circuit 43 ₄ by the coefficient a by the multiplication circuit 44 ₁ by a and input as a subtraction signal. Therefore, the adder circuit 45 ₂ forms a signal obtained by subtracting the signal of the surround right channel and the signal of the center channel from the signal of the mixed light channel, that is, a signal of the right channel containing mixed noise. The light channel signal containing this mixed noise is sent to the adder circuit 46 ₂ as an added signal.

The de-matrix means 14 of FIG. 1 corresponds to the configuration for forming the right channel signal containing the mixed noise similarly to the left channel signal containing the mixed noise.

Next, in the adder circuit 46 ₁ , the left channel signal containing the mixed noise from the adder circuit 45 ₁ is used as an added signal, and the left channel signal containing the mixed noise from the decoding circuit 43 ₁ is added. By performing the addition operation using the channel error signal Le generated from the channel as the subtraction signal, the error correction of the signal of the left channel including the mixed noise is performed. The output signal of the adder circuit 46 ₁ are sent to the output terminal 47 ₁ as a signal of the error-corrected left channel.

In addition, in the adder circuit 46 ₂ , the signal of the write channel containing the mixed noise from the adder circuit 45 ₂ is used as an added signal, and the write channel from the decoding circuit 43 ₇ containing the mixed noise is included. By performing an addition operation using the channel error signal Re generated by the above as a subtraction signal, the error correction of the signal of the write channel including the above-mentioned mixed noise is performed. The output signal of the adder circuit 46 ₂ is sent to the output terminal 47 ₅ as an error-corrected write channel signal.

These adder circuits 46 ₁ and 46 ₂ correspond to the error correction means 15 in FIG.

Of the signals decoded by the decoding circuits 43 ₁ to 43 ₇ , the decoded signals corresponding to the signals of the channels independently coded by the coding apparatus of FIG. 3, this example Then, the decoded signals of the center channel, the surround left channel, and the surround right channel are output from the corresponding output terminals 47 ₂ to 4 7.
It is output from 7 ₄ .

As is apparent from the above-mentioned configuration, the present invention encodes signals of some encoded channels, whereas the conventional example only encodes signals of each channel. Decoding is performed in the device, and a differential signal (channel error signal) is obtained by a predetermined calculation. Such partial decoding is called local decoding. A channel error signal is obtained by using the signal obtained by this local decoding, and the decoding device obtains a channel error signal and a channel including mixed noise. The signal of each channel is calculated and finally the signal of each channel is formed.

Next, the waveform of each part in the configuration of FIGS. 3 and 4 is shown in FIG. 5, and the effect of the specific example of the present invention will be described with reference to FIG.

FIG. 5A shows the input terminal 21 _{1 of} FIG.
Each channel input to _{~21 5 (L), (R} ),
The signal waveform examples of (C), (SL), and (SR) are shown. The signal waveform of FIG. 5A has the same signal waveform as that of FIG. 11A for comparison with FIG. 11. Further, in FIG. 5B, the signals of the respective channels shown in FIG. 5A are input to the encoding circuits 24 _{1 to} 24 ₅ after the premix processing in the configuration of FIG. The channel signal waveforms and the channel error signal waveforms output from the adder circuits 28 ₁ and 28 ₂ are shown. That is, Lm in FIG. 5B is the signal waveform of the mixed left channel, Rm is the signal waveform of the mixed right channel, and the other three channels (C), (SL), (S).
The signal waveform of (R) is the same as that of (a) of FIG. Further, Le in FIG. 5B is a channel error signal waveform output from the adder circuit 28 ₁ , and Re in FIG. 5B is a channel error signal waveform output from the adder circuit 28 _2. is there. The signal of each channel shown in FIG. 5B corresponds to the signal on the recording medium or the transmission path. Further, in FIG. 5C, the signals of the respective channels shown in FIG. 5B are sent to the configuration shown in FIG. 4, where the decoding circuits 43 ₁ to 43 corresponding to the respective channels are sent. decoded by _7, and each channel obtained by the arrangement of the structure and error correction process dematrixing process in the Figure 4 (L), a signal waveform example (R), (C), (SL), (SR) (i.e. waveform example of a signal output from the output terminal 47 ₁ to 47 ₅₎ shows.

The signal waveform of FIG. 5C and FIG.
As is apparent from comparison with the signal waveform of (c), according to the above-described specific example of the present invention, the mixed noise of the left channel signal and the right channel signal is reduced.

In the specific example described above, an example of a system (multi-channel system) using 5 channels as a plurality of channels is given, but the present invention is not limited to the number of channels. For example, 5 as in the above example
In addition to the channels, a left center channel is provided between the left channel and the center channel,
The present invention can also be applied to a multi-channel system having a total of 7 channels in which a light center channel is provided between the center channel and the light channel. Further, it can be similarly applied to the number of channels more than that, or conversely less (for example, 4 channels or 3 channels).

Further, in the above-mentioned specific example, the left channel and the right channel are taken as examples of the channels which are not independently encoded, but the independent channel can be obtained by using the method for switching the content of the channel to be encoded as described above. A channel that is not coded in can be an arbitrary channel.

Furthermore, the signal formed by the encoding method or device of the present invention can be recorded as a recording medium on various recording media such as a film, a tape-shaped recording medium, and a semiconductor memory in addition to the optical disc. . It is also possible to transmit via a transmission line such as a telephone line or broadcasting.

[0104]

As is apparent from the above description, in the present invention, a mixed channel signal for allowing multi-channel audio or voice signals to be reproduced by a simple decoding device is also included. When encoding, the noise generated by dematrixing the mixed-channel signal is used to de-matrix the mixed-channel signal to obtain the non-encoded non-independent channel signal and the non-independent channel before premixing. By including it in the code string signal as the difference signal with the signal of, it is possible to suppress the increase in the number of bits due to the increase in the number of channels and suppress the generation of noise due to premix processing and dematrix processing. Thus, higher coding efficiency can be realized.

[Brief description of drawings]

FIG. 1 is a block circuit diagram showing a basic configuration of an information encoding device that realizes an information encoding method of the present invention.

FIG. 2 is a block circuit diagram showing a basic configuration of an information decoding device for realizing the information decoding method of the present invention.

FIG. 3 is a block circuit diagram showing a specific configuration of the information encoding device of the present invention.

FIG. 4 is a block circuit diagram showing a specific configuration of the information decoding device of the present invention.

FIG. 5 is a waveform diagram for explaining the effect of the specific example of the present invention.

FIG. 6 is a block circuit diagram showing a schematic configuration of a conventional encoding device that directly encodes signals of a plurality of channels.

FIG. 7 is a block circuit diagram showing a schematic configuration of a conventional decoding device that decodes signals of a plurality of channels from a code string signal in which signals of a plurality of channels are encoded.

FIG. 8 is a block circuit diagram showing a configuration example of a conventional encoding device using a premix process.

FIG. 9 is a block circuit diagram showing a configuration example of a simple decoding device that reproduces only a 2-channel signal from a premixed code string signal.

FIG. 10 is a block circuit diagram showing a configuration example of a conventional decoding device that dematrixes a premixed code string signal.

FIG. 11 is a waveform diagram showing signal waveforms of respective units of a conventional encoding device and decoding device that perform premix processing and dematrix processing.

FIG. 12 is a block circuit diagram showing a configuration example of a conventional encoding device for encoding signals of a premixed channel and an independent channel.

[Explanation of symbols]

 2 premix means 3 encoding means 4 decoding means 5, 14 dematrixing means 6 error signal detecting means 7 error signal coding means 8 multiplexing means 12 demultiplexing means 13 decoding means 14 dematrixing means 15 error correcting means

Claims (11)

[Claims] 1. An information encoding method for encoding signals of a plurality of channels, wherein an independent channel signal independently encoded and a non-independent channel signal not independently encoded are mixed. A channel mixing step of generating the signal of the above, a channel signal encoding step of encoding the above-mentioned mixed channel signal and the above-mentioned independent channel signal, the above-mentioned encoded mixed channel signal, and the above A channel signal decoding step of decoding an independent channel signal, and a channel signal generation for generating a non-independent channel signal from the decoded mixed channel signal and the decoded independent channel signal Process, the signal of the non-independent channel generated in the channel signal generation process, and the non-independent channel before mixing. Difference signal generating step of generating a difference signal with the signal of, a difference signal encoding step of encoding the difference signal, the encoded independent channel signal, and the encoded mixed channel signal And a code string generation step of generating a code string signal from the coded difference signal. 2. In the channel mixing step, a signal obtained by multiplying the signal of the independent channel by a predetermined coefficient is added to the signal of the non-independent channel,
2. The information coding method according to claim 1, wherein the mixed channel signal is generated. 3. The non-independent channel is generated by subtracting a signal obtained by multiplying the decoded independent channel signal by a predetermined coefficient from the decoded mixed channel signal in the channel signal generating step. 2. The information encoding method according to claim 1, wherein the signal is generated. 4. An information encoding apparatus for encoding signals of a plurality of channels, wherein an independent channel signal independently encoded and a non-independent channel signal not independently encoded are mixed and mixed channel. Channel mixing means for generating the signal of the above, a channel signal coding means for coding the signal of the above-mentioned mixed channel, and the signal of the above-mentioned independent channel, the above-mentioned coded mixed-channel signal, and the above-mentioned coded Channel signal decoding means for decoding an independent channel signal, a channel signal generator for generating a non-independent channel signal from the decoded mixed channel signal and the decoded independent channel signal Means, the non-independent channel signal generated by the channel signal generating means, and the non-independent channel before mixing. Difference signal generating means for generating a difference signal with respect to the signal, difference signal encoding means for encoding the difference signal, the encoded independent channel signal, and the encoded mixed channel signal An information coding apparatus, comprising: a code string generating means for generating a code string signal from the coded difference signal. 5. The channel mixing means generates the mixed channel signal by adding a signal obtained by multiplying the independent channel signal by a predetermined coefficient to the non-independent channel signal. The information encoding device according to claim 4, characterized in that 6. The non-independent channel is generated by subtracting a signal obtained by multiplying the decoded independent channel signal by a predetermined coefficient from the decoded mixed channel signal. The information coding apparatus according to claim 4, wherein the information coding apparatus generates the signal of. 7. An information decoding method for decoding a signal of a plurality of channels from a code string signal obtained by coding a signal of a plurality of channels, wherein an independent channel signal independently coded from the code string signal is provided. A mixed channel signal generated by mixing a non-independent channel signal that is not independently encoded and the independent channel signal, and the encoded independent channel signal and the encoded mixture, A separation step of separating a non-independent channel signal generated from the channel signal and an encoded difference signal representing the difference between the non-independent channel signal before mixing, and the encoded independent channel signal A signal decoding step of decoding the coded mixed-channel signal and the coded difference signal; and the decoded independent signal. A channel signal generating step of generating a non-independent channel signal from the channel signal and the decoded mixed channel signal; a non-independent channel signal generated in the channel signal generating step; And an addition step of adding the generated difference signal. 8. The non-independent channel is generated by subtracting a signal obtained by multiplying the decoded independent channel signal by a predetermined coefficient from the decoded mixed channel signal in the channel signal generating step. The information decoding method according to claim 7, wherein the signal is generated. 9. An information decoding apparatus for decoding a signal of a plurality of channels from a code string signal obtained by coding a signal of a plurality of channels, wherein an independent channel signal independently coded from the code string signal is provided. A mixed channel signal generated by mixing a non-independent channel signal that is not independently encoded and the independent channel signal, and the encoded independent channel signal and the encoded mixture, Signal separating means for separating a non-independent channel signal generated from a channel signal and an encoded difference signal representing the difference between the independent channel signal before mixing, and the encoded independent channel signal A signal decoding means for decoding the coded mixed channel signal and the coded difference signal; and the decoded single signal. A channel signal generating means for generating a non-independent channel signal from a vertical channel signal and the decoded mixed channel signal, a non-independent channel signal generated by the channel signal generating means, and the decoding An information decoding device, comprising: an addition unit that adds the digitized difference signal. 10. The non-independent channel is generated by the channel signal generating means by subtracting a signal obtained by multiplying the decoded independent channel signal by a predetermined coefficient from the decoded mixed channel signal. The information decoding apparatus according to claim 9, wherein the information decoding apparatus generates the signal of. 11. A recording medium in which encoded signals of a plurality of channels are recorded, an independently encoded independent channel signal, an independently unencoded non-independent channel signal, and the independent channel. Signal of the mixed channel coded by mixing the signal of the above, the coded independent channel signal and the non-independent channel signal generated from the coded mixed channel signal, and the non-mixed signal before mixing. A recording medium characterized by recording a code string signal composed of an encoded difference signal representing a difference from an independent channel signal.