JPH07283738A - Highly efficient coding method/device for multichannel audio data - Google Patents

Abstract

PURPOSE:To provide a device which can encode the multichannel audio data with high efficiency and with a high compression rate regardless of the degree of correlation of digital data among plural channels. CONSTITUTION:The primary requantization means 225a-225h requantize the coded audio data and also generate the parameter information on these coding operations. A detector means 226 detects the common items based on the audio data that are requantized by the means 225a-225h and the parameter information. Then the secondary requantization means 227a-227h requantize at least some of those common items detected by the means 226.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-efficiency coding method for multi-channel audio data in a compression coding process for multi-channel digital signals and a high-efficiency coding apparatus therefor. The present invention relates to a high-efficiency encoding method of multi-channel audio data and a high-efficiency encoding apparatus suitable for use in a stereo system such as a system, a video tape recorder, a video disc player, and so-called multi-sound audio system.

[0002]

2. Description of the Related Art There are various techniques for high-efficiency coding of audio data or voice signals, for example, a block frequency band division method, so-called transform coding (transform coding), or non-block frequency band division. Method, so-called band division coding (subband coding: S
BC) etc.

The transform coding is performed by dividing audio data in the time domain into blocks for each unit time, and transforming the data on the time axis of each block into data on the frequency axis, that is, orthogonal transform, and further converting the data. This is a method of dividing into frequency bands of and encoding each band. The band division encoding is a method of dividing time-domain audio data or the like into a plurality of frequency bands and encoding them without blocking them every unit time.

A high-efficiency coding method combining the above-described transform coding and band division coding has also been considered. In this high efficiency coding, for example, the audio data in the time domain is band-divided by the above band-division coding, and then the data for each band is orthogonally transformed into the data in the frequency domain, and this orthogonal transformation is performed. This is a method of encoding data in each area.

Here, as the band division filter of the above band division encoding, for example, there is a filter such as QMF. E. Crooire Di
digital coding of speech in
subbands Bell System.Tech.
J. Vol 55, No. 8 1976. In addition, ICASSP 83, BOSTON Po
lyphase quadrature filter
s-A new subband coding tec
hique Joseph H.M. Rothweiler
Describes an equal bandwidth filter partitioning method and apparatus.

As the above-mentioned orthogonal transform, for example, input audio data is input in a predetermined unit time (frame).
Fast Fourier transform (FFT), cosine transform (DCT), improved discrete cosine transform, so-called modified DCT transform (hereinafter referred to as MDC)
T: Modified Discrete Trans
It is called form. ) There is an orthogonal transformation that transforms the time axis into the frequency axis by performing the above. About this MDCT, ICASSP 1987 Subband /
Transform Coding Using Fi
lter BankDesigns based on
Time Doma AligningCancel
relation J. P. Princen A. B. Br
adlayUniv. of Surrey Royal
Melbourn Inst. of Tech.

Further, as the frequency division width in the case of quantizing each frequency component obtained by frequency band division, there is, for example, band division in consideration of human auditory characteristics. That is, audio data may be divided into a plurality of bands, for example, 25 bands, with a bandwidth that is generally called a critical band and becomes wider in a higher band. Further, at the time of encoding the data of each band at this time, encoding is performed by predetermined bit allocation for each band or adaptive bit allocation for each band. For example,
When the coefficient data obtained by the MDCT processing is encoded by the bit allocation, the number of adaptive allocation bits is set to the MDCT coefficient data for each band obtained by the MDCT processing for each block. Encoding is performed.

The following two methods and their apparatuses are known as the above-mentioned bit allocation method and its apparatus. IEEE
E Transactions of Accoust
ics, Speech, and Signal Pro
cessing, vol. ASSP-25, No. 4,
August 1977 describes a method and apparatus for allocating bits based on the size of data in each band. In addition, ICASSP 1980 The
critical band coder-digit
al encod of the perceptua
l requirements of the aud
itory system M.I. A. Kransner
In MIT, a method and an apparatus for performing fixed bit allocation by obtaining a necessary signal-to-noise ratio for each band by utilizing auditory masking are described.

By the way, for example, in the high-efficiency compression coding method of audio data using the band division coding or the like as described above, the audio data is compressed to about ⅕ using human auditory characteristics. Method (below,
This is called the 1/5 compression method. ) Has already been put to practical use.

Not only in the case of ordinary audio equipment, but also in stereo systems such as movie film projection systems, high-definition televisions, video tape recorders, video disc players, and so-called multi-sound audio systems, the range from 4 to 4 is used. A plurality of 8-channel audio data or audio signals are being handled. Even in this case, it is desired to perform high efficiency coding that reduces the bit rate.

For example, in the above-mentioned motion picture film, as shown in FIG. 7, a video recording area 50 in which an image to be projected is recorded.
1. Perforation unit 502L and perforation unit 502 for conveying a motion picture film for projection
R, analog sound track 503L and analog sound track 503R provided to enable reproduction of audio signals even with conventional equipment, digital sound track 504L and digital sound track 504 for recording multi-channel digital audio data.
With R.

Here, the digital soundtrack 5
04L and digital sound track 504R, for example, to record 8-channel digital audio data of left channel, left center channel, center channel, right center channel, right channel, surround left channel, surround right channel, subwoofer channel In some cases, high efficiency coding that reduces the bit rate is required.

That is, for example, the area in which the 16-bit linearly quantized 8-channel audio data can be recorded at a sampling frequency of 44.1 kHz as used in a compact disc (hereinafter referred to as a CD) or the like, It is difficult to secure it on the motion picture film.
Therefore, it is necessary to compress the audio data.

The above-mentioned 8 recorded on the above-mentioned motion picture film
Each of the channels is, for example, as shown in FIG. 8, a left speaker 551, a left center speaker 552, a center speaker 552 arranged on the screen 550 side on which an image reproduced from the image recording area of the movie film is projected by a projector. The speaker 553, the light center speaker 554, the right speaker 555, the subwoofer speaker 556, and the surround left speaker 558 and the surround right speaker 559 which are arranged so as to surround the audience seat 557, respectively.

Here, the center speaker 553 is
It is arranged in the center of the screen 550 side and outputs a reproduced sound based on the audio data of the center channel. For example, the most important reproduced sound such as an actor's dialogue is output.
The subwoofer speaker 556 outputs a reproduced sound based on audio data of the subwoofer channel, and effectively outputs a sound that is felt as vibration rather than a low frequency sound such as an explosion sound. It is often used effectively in scenes.

The left speaker 551 and the right speaker 555 are disposed on the left and right of the screen 550, and output a reproduced sound by the left channel audio data and a reproduced sound by the right channel audio data, and exhibit a stereo sound effect. To do. The left center speaker 552 is the left speaker 55.
1 and the center speaker 553, and the light center speaker 554 is arranged between the center speaker 553 and the light speaker 555. The left center speaker 552 outputs a reproduced sound based on audio data of the left center channel, and the right center speaker 554 outputs a reproduced sound based on audio data of the right center channel. The left center speaker 552 outputs the reproduced sound based on the audio data of the right center channel. Play an auxiliary role. Particularly in a movie theater or the like where the screen 550 is large and the number of seats is large, the localization of the sound image tends to be unstable depending on the position of the seat. However, by adding the left center speaker 552 and the right center speaker 554, the sound image can be more realistic. It is effective in creating localization.

Further, the surround left speaker 5
The 58 and the surround right speaker 559 are arranged so as to surround the spectators' seats, and output a reproduced sound by the audio data of the surround left channel and a reproduced sound by the audio data of the surround right channel. It has the effect of giving a mixed impression. As a result, a more stereoscopic sound image can be created.

Further, since a medium called a film is liable to have scratches on its surface, if digital data is recorded as it is, the data is seriously lost and it is not practical. For this reason, the capability of the error correction code becomes very important, and the data compression must be performed to the extent that it can be recorded in the recording area on the film including the correction code.

Therefore, the 1/5 compression method is applied as the compression method for compressing the 8-channel digital audio data. That is, by optimally allocating bits in consideration of human hearing characteristics, 16-bit digital audio data at a sampling frequency of 44.1 kHz such as that recorded on a CD or the like can be compressed to about 1/5. , A high-efficiency coding method that achieves sound quality comparable to that of a CD is applied.

The high-efficiency coding apparatus to which the 1/5 compression method as described above is applied receives 8-channel digital audio data (hereinafter referred to as audio data), for example, as shown in FIG. Input terminals 101 to 1
09, encoders 111 to 119 for respectively encoding audio data of the respective channels input via the input terminals 101 to 109, and audio data of the respective channels encoded by the encoders 111 to 119. It is composed of a multiplexer 120 that collects one data without changing the value at all and an output terminal 130 that outputs the data collected by the multiplexer 120. Here, the encoders 111 to 119 are provided corresponding to the audio data of the respective channels input via the input terminals 101 to 109, and perform encoding for each channel.

The 8-channel audio data input via the input terminals 101 to 109 is encoded by the encoders 111 to 111.
By 119, encoding is performed for each channel using the 1/5 compression method. Then, the encoded audio data of each channel is output to the multiplexer 120.
Is supplied to each. The multiplexer 120 collects the encoded audio data values of the respective channels from the encoders 111 to 119 into one data without any change, and outputs the collected data into one output terminal 1.
Output via 30.

[0022]

[Problems to be Solved by the Invention]

Here, for example, when stereo data has a strong correlation between data of two channels and similar data which is not completely the same is inputted, the code for each channel is encoded. The encoded data and the parameter information of the encoding tend to be similar.

However, the 1/5 compression method is an encoding method for a single channel, and since the encoding is performed for each channel, if the 1/5 compression method is used in the encoding processing of multi-channel audio data. However, it was not possible to perform effective data coding processing using elements such as data dependency between channels, data characteristics of each channel, and format characteristics.

On the other hand, as a coding process using the correlation between the data between the channels, when the respective data of the above two channels are matched, the matched data are made common to be represented by one channel. There is a method (Japanese Patent Application No. 5-267251). However, this method exhibits its effect when the correlation between the data between the multi-channels is strong, but on the contrary, when the correlation is weak, the effect cannot be sufficiently obtained, and the appropriate data encoding processing is performed. I couldn't.

In view of the above, the present invention can realize high compression in multi-channel digital audio data compression coding regardless of the degree of correlation of digital data between multi-channels. Another object of the present invention is to provide a multi-channel audio data high-efficiency coding method and a high-efficiency coding apparatus thereof which can use existing decoding devices.

[0027]

A high-efficiency coding method for multi-channel audio data and a high-efficiency coding apparatus according to the present invention have been proposed to achieve the above-mentioned object, and Obtaining encoding parameter information and encoded digital audio data, detecting a common term from the parameter information and the encoded digital audio data, by requantizing at least a part of the common term, The output parameter information and encoded digital audio data are reduced. Thereby, the compression rate is increased.

Further, the common term is detected between the channels, and the common term is requantized between the channels. Or
When the correlation between channels is weak, a common term is detected between sound frames that are temporally adjacent to each other for each channel, and the common term between the sound frames is requantized.
Alternatively, the common term is detected between adjacent units in each band obtained by dividing the digital audio data of the channel into a plurality of frequency bands, and the common term between the units is requantized.
The re-quantization means as described above is selected by using a predetermined evaluation function to further increase the compression rate. Further, by performing the above-mentioned requantization for each band obtained by dividing the digital audio data of each channel into a plurality of frequency bands, it is possible to perform encoding in accordance with the frequency characteristic of the digital signal.

That is, a high-efficiency encoding method for multi-channel audio data according to the present invention is a high-efficiency encoding method for encoding digital audio data of a plurality of channels and obtaining parameter information for the encoding. , A common term is detected from the encoded audio data and the parameter information, and at least a part of the common term is requantized.

The high-efficiency coding method for multi-channel audio data according to the present invention is characterized by detecting a common term between channels and requantizing the common term between the channels.

In addition, the method for highly efficient encoding of multi-channel audio data according to the present invention detects a common term between sound frames that are temporally adjacent to each channel and requantizes the common term between the sound frames. It is characterized by doing.

Further, the high-efficiency coding method for multi-channel audio data according to the present invention detects the common term between adjacent units in each band obtained by dividing the digital audio data of the channel into a plurality of frequency bands, and detects the common term between the units. It is characterized by requantizing the common term of.

In addition, the high-efficiency encoding method for multi-channel audio data according to the present invention comprises a common term between channels, a common term between sound frames temporally adjacent to each channel, and a plurality of frequencies of digital audio data of the channels. Each common term between adjacent units of each band divided into bands is detected, and each detection result is evaluated using a predetermined evaluation function. Based on the evaluation result, at least one of the common terms between channels is detected. First to requantize parts
Requantization method, a second requantization method of requantizing at least a part of common terms between sound frames that are temporally adjacent to each other for each channel, and digital audio data of channels in a plurality of frequency bands. Requantizing the common term by designating a requantization method from among a third requantization method of requantizing at least a part of the common term between adjacent units of each divided band. To do.

A high-efficiency encoder for multi-channel audio data according to the present invention encodes digital audio data of a plurality of channels, outputs the encoded audio data, and outputs the encoding parameter information. A high-efficiency encoding device for requantizing the audio data and generating parameter information for the encoding, and requantizing the audio data by the primary requantizing means. The present invention is characterized by including detection means for detecting a common term from the parameter information, and secondary requantization means for requantizing at least a part of the common term detected by the detection means.

Further, in the high-efficiency encoding apparatus for multi-channel audio data according to the present invention, the detecting means comprises:
The common term between channels is detected, and the secondary requantization means requantizes the common term between channels.

Further, in the high-efficiency encoding apparatus for multi-channel audio data according to the present invention, the detecting means is
The common term between sound frames temporally adjacent to each other is detected for each channel, and the secondary requantization means requantizes the common term between sound frames temporally adjacent to each other for each channel. And

Further, in the high efficiency encoding apparatus for multi-channel audio data according to the present invention, the detecting means is
A common term between adjacent units in each band obtained by dividing the digital audio data of a channel into a plurality of frequency bands is detected, and the secondary requantization means is provided for each band obtained by dividing the digital audio data of each channel into a plurality of frequency bands. Is characterized by requantizing the common term between adjacent units of.

Further, in the high-efficiency coding apparatus for multi-channel audio data according to the present invention, the secondary requantization means includes first requantization means for requantizing common terms between channels, and Second requantization means for requantizing common terms between sound frames that are temporally adjacent to each other, and the common term between adjacent units of each band obtained by dividing digital audio data of a channel into a plurality of frequency bands. And a third requantization means for requantizing each of the sound frames, wherein the detection means detects first common term detection means for detecting a common term between channels, and between sound frames temporally adjacent to each other for each channel. Second common term detecting means for detecting a common term of the channel, and a second common term detecting means for detecting a common term between adjacent units in each band obtained by dividing the digital audio data of the channel into a plurality of frequency bands. Common term detecting means, the first common term detecting means, the second common term detecting means and the third common term detecting means, and the evaluating means for evaluating the detection results of the common terms using a predetermined evaluation function. And a means for requantizing based on the evaluation result by the evaluating means is selected and specified from the first requantizing means, the second requantizing means, and the third requantizing means. Requantization designating means for

[0039]

According to the present invention, when the digital audio data of each channel is encoded by the existing single-channel encoding method, if the digital audio data of each channel has strong correlation, parameter information and Encoded digital audio data tends to match. Therefore, by suppressing the redundancy by requantizing at least a part of the common parameters of the matched parameter information and the encoded digital audio data,
Parameter information or channels that are not similar in encoded digital audio data are discriminated, and a common term between sound frames temporally adjacent to each other,
Alternatively, by suppressing at least a part of the common term between the adjacent units in each band obtained by dividing the digital audio data of the channel into a plurality of frequency bands, the reduction of the sound quality due to the requantization of the common term is suppressed. I am trying.

That is, in the high-efficiency encoding method for multi-channel audio data according to the present invention, digital audio data of a plurality of channels are each encoded, and
A high-efficiency encoding method for obtaining parameter information for the encoding, which detects a common term from the encoded audio data and the parameter information and requantizes at least a part of the common term.

Further, in the high-efficiency encoding method for multi-channel audio data according to the present invention, the common term between the channels is detected and the common term between the channels is requantized.

Further, in the high-efficiency encoding method for multi-channel audio data according to the present invention, a common term is detected between sound frames temporally adjacent to each channel, and the common term between the sound frames is requantized. To do.

Further, in the high-efficiency encoding method for multi-channel audio data according to the present invention, the common term is detected between the adjacent units in each band obtained by dividing the digital audio data of the channel into a plurality of frequency bands, and the units are connected to each other. Requantize the common term of.

In addition, in the high-efficiency encoding method for multi-channel audio data according to the present invention, the common term between channels and the common term between sound frames temporally adjacent to each other and the digital audio data of the channels have a plurality of frequencies. The common term between adjacent units of each band divided into bands is detected. Each detection result is evaluated using a predetermined evaluation function. Further, based on the evaluation result, a first requantization method for requantizing at least a part of common terms between channels and at least one of common terms between sound frames temporally adjacent to each channel. And a third requantization method for requantizing at least a part of common terms between adjacent units in each band obtained by dividing digital audio data of a channel into a plurality of frequency bands. Specify the requantization method from the quantization methods. When the first requantization method is designated, at least part of the common term between channels is requantized. When the second requantization method is specified,
At least a part of the common term between the sound frames temporally adjacent to each other is requantized. Also, the third
When the re-quantization method is specified, at least a part of common terms between adjacent units of each band obtained by dividing the digital audio data of the channel into a plurality of frequency bands is re-quantized.

In the high-efficiency encoder for multi-channel audio data according to the present invention, digital audio data of a plurality of channels are each encoded, the encoded audio data is output, and the encoding parameter information is output. In the high-efficiency coding device, the primary requantization means requantizes the audio data and generates parameter information for the coding. The detecting means detects a common term from the audio data requantized by the primary requantizing means and the parameter information. The secondary requantization means requantizes at least a part of the common term detected by the detection means.

In the high-efficiency coding apparatus for multi-channel audio data according to the present invention, the detecting means detects a common term between channels. The secondary requantization means requantizes the common term between channels.

Further, in the high-efficiency encoder for multi-channel audio data according to the present invention, the detecting means detects a common term between sound frames which are temporally adjacent to each other for each channel. The secondary requantization means requantizes the common term between sound frames that are temporally adjacent to each other for each channel.

In the multi-channel audio data high-efficiency encoder according to the present invention, the detecting means detects a common term between adjacent units in each band obtained by dividing the digital audio data of the channel into a plurality of frequency bands. To do. The secondary requantization means requantizes the common term between adjacent units in each band obtained by dividing the digital audio data of each channel into a plurality of frequency bands.

Further, in the high-efficiency coding apparatus for multi-channel audio data according to the present invention, the first requantization means of the secondary requantization means requantizes the common term between channels. The second requantization means of the second-order requantization means requantizes the common term between sound frames temporally adjacent to each other for each channel. The third requantization means of the second-order requantization means requantizes the common term between the adjacent units of each band obtained by dividing the digital audio data of the channel into a plurality of frequency bands. The first common term detecting means of the detecting means detects a common term between channels. The second common term detecting means of the detecting means detects a common term between sound frames that are temporally adjacent to each other for each channel. The third common term detecting means of the detecting means detects a common term between adjacent units in each band obtained by dividing the digital audio data of the channel into a plurality of frequency bands. The evaluation means of the detection means evaluates the detection results of the common terms of the first common term detection means, the second common term detection means, and the third common term detection means, respectively, using a predetermined evaluation function. The requantization designation means of the detection means includes means for requantizing based on the evaluation result by the evaluation means, the first requantization means, the second requantization means, and the third requantization means. Select and specify from among the means of conversion.

[0050]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

The high-efficiency encoding method for multi-channel digital audio data according to the present invention is realized, for example, by the high-efficiency encoding device having the configuration shown in FIG.
The high-efficiency coding apparatus applies the 1/5 compression method, and as shown in the figure, input terminals 1a to 1h to which 8-channel digital audio data are respectively input.
And encoding audio data of each channel input through the input terminals 1a to 1h, and obtaining parameter information of the encoding, and at least a part of common items of the encoded audio and the parameter information. Common channel coder 2 for requantizing data, a multiplexer 3 for collecting the requantized audio data of each channel from the common channel coder 2 and parameter information into one data, and the multiplexer 3
Output terminal 4 that outputs the data collected by
It consists of and.

As shown in FIG. 2, the common channel encoder 2 divides the audio data input through the input terminals 1a to 1h into a plurality of frequency bands, and also divides the audio data into time and frequency bands. The dividing means 21a to 21h for decomposing into signal components on the two-dimensional area and the audio data of each channel from the dividing means 21a to 21h are coded, the parameter information of the coding is obtained, and the coded audio is obtained. A requantizer 22 for requantizing the common term of the data and the parameter information, and a formatter for respectively assembling the parameter information from the requantizer 22 and the requantized audio data into a bitstream according to a predetermined format. 23a ~
23h.

The dividing means 21a to 21h will be described. Here, the dividing means 21a to 21h have the same configuration, and are provided for each channel corresponding to audio data input via the input terminals 1a to 1h.

For example, the dividing means 21a has an input terminal 21 to which audio data is input, as shown in FIG.
1, a band division filter 212 that divides the audio data input through the input terminal 211 into three frequency bands, and each audio data that is divided into three frequency bands by the band division filter 212.
Two-dimensional area of time and frequency after CT calculation (hereinafter, block floating unit: Block Float
It is called ing Unit. ) The MDCT operation unit 213 that decomposes the above signal components and the unit processing unit 4 that normalizes the audio data of each frequency band decomposed into the signal components on the block floating unit by the MDCT operation unit 213. It is configured.

The band division filter 212 converts the audio data input via the input terminal 211 from 0 to
It is divided into three frequency bands, a low frequency band of 5.5 kHz, a middle frequency band of 5.5 kHz to 11 kHz, and a high frequency band of 11 kHz to 22 kHz.

The MDCT operation unit 213 performs a MDCT operation on the low frequency band audio data divided by the band division filter 212 and performs MDCT operation on the audio data in the low frequency band.
A mid-range MDCT circuit 213M that performs CT calculation and a high-range M that performs MDCT calculation on audio data in a high frequency band
DCT circuit 213H and the above low frequency MDCT circuit 213L
And mid-range MDCT circuit 213M and high-range MDCT circuit 213
MDCT for audio data of each frequency band in H
And a block size evaluator 213S that determines the time block length for performing the calculation.

Here, the block size evaluator 213 is used.
S shortens the time block length in the portion where the audio data of each frequency band changes abruptly, and lengthens the time block length in the portion where the audio data is steady, and the MDCT calculation is performed for each frequency band. The time block length is determined, and information indicating the determined time block length is given to the low band MDCT circuit 213L, the middle band MDCT circuit 213M, and the high band MDCT circuit 213H, respectively. As a result, the time resolution is increased in the portion where the audio data changes abruptly, and the effective transmission of the signal component and the quantization noise are controlled in the portion where the audio data is stationary.

The above long time block length is called a long mode and corresponds to a time of 11.6 ms. Also,
The short time block length is called the short mode, and it is up to 1.45 ms in the high range (11 to 22 kHz) and low range (0 to 22 kHz).
5.5 kHz) and mid range (5.5 kHz to 11 kHz)
Then, the time resolution is increased up to 2.9 ms.

With the above-mentioned configuration, the MDCT operation unit 213 performs MDCT operation while controlling the time block length for the audio data divided into each frequency band from the band division filter 212, thereby obtaining the time and frequency. The block floating unit (hereinafter referred to as a unit) is decomposed into signal components.

The unit processing section 214 has the MDC.
A low-frequency normalization circuit 214L that divides the audio data in the low-frequency band decomposed into signal components on the unit by the T operation unit 213 into units and normalizes, that is, normalizes by using a scale factor for each unit, A mid-range normalization circuit 214M that divides the audio data in the mid-frequency band decomposed into the signal components on the unit into units and positively normalizes using a scale factor for each unit, and decomposes into the signal components on the unit The high frequency band normalization circuit 214H that normalizes the audio data of the high frequency band thus generated into units and uses the scale factor for each unit, and the low frequency band normalization circuit 21.
4L, the mid-range normalization circuit 214M, and the high-range normalization circuit 214H, and a bit distributor 214S for analyzing what kind of component the audio data supplied from the MDCT operation unit 213 is made up of. ing.

The low frequency band normalization circuit 214L divides the supplied low frequency band audio data into 20 units, and the mid frequency band normalization circuit 214M divides the supplied low frequency band audio data. The audio data of the supplied high frequency band is divided into 16 units by the high frequency normalization circuit 214H. That is, each audio data in the low frequency band, the middle frequency band, and the high frequency band is divided into a total of 52 units.

Next, the dividing means 2 configured as described above.
The operation of 1a will be described.

Although not shown, the audio data input through the input terminal 211 is sampled and quantized, and the band division filter 212 is input through the input terminal 211.
Is supplied to. The band division filter 212 has an input terminal 2
The audio data input via 11 is divided into three frequency bands of low frequency band, middle frequency band and high frequency band, and the audio data divided into these three frequency bands is MD.
It is supplied to the CT calculation unit 213.

From the band division filter 212 to the MD
The audio data in the low frequency band supplied to the CT calculation unit 213 is input to the low frequency MDCT circuit 213L, and the audio data in the intermediate frequency band is supplied to the intermediate MDCT circuit 213M.
, High frequency band audio data is high frequency MDCT
The audio data in the three frequency bands of the low frequency band, the middle frequency band, and the high frequency band is supplied to the circuit 213H, and is also supplied to the block size evaluator 213S.

The low frequency MDCT circuit 213L controls the audio data of the low frequency band from the band division filter 212 while controlling the time block length of MDCT operation by the block size evaluator 213S to MDC.
Perform T calculation. The mid-range MDCT circuit 213M adds the mid-range frequency band audio data from the band division filter 212 to the MD while controlling the time block length of the MDCT operation by the block size evaluator 213S.
Perform CT calculation.

The high-frequency MDCT circuit 213H applies MDC to the audio data in the high-frequency band from the band division filter 212 while controlling the time block length of MDCT operation by the block size evaluator 213S.
Perform T calculation.

As described above, the low frequency MDCT circuit 21 is
3L and mid-range MDCT circuit 213M and high-range MDCT circuit 2
The audio data decomposed into signal components on the unit of time and frequency for each frequency band by 13H is supplied to the unit processing unit 214.

The audio data in the low frequency band decomposed into the signal components on the unit from the MDCT operation unit 213 is sent to the low frequency normalization circuit 214L and the audio in the middle frequency band decomposed into the signal components on the unit. The data is supplied to the mid-range normalization circuit 214M, and the audio data in the high-frequency band decomposed into the signal components on the unit are supplied to the high-range normalization circuit 214H, and the low-range, mid-range, and high-range audio data are supplied. The audio data of the three frequency bands in the range is also supplied to the bit allocator 214S.

The low-frequency normalization circuit 214L uses the MD
The low frequency band audio data decomposed into signal components on the unit from the CT calculation unit 213 is decomposed into 20 units, and each unit is normalized using a scale factor, and the normalized audio data is Output. The mid-range normalization circuit 214M includes the MDC.
The audio data in the middle frequency band decomposed into signal components on the unit from the T calculation unit 213 is decomposed into 16 units, and each unit is normalized using a scale factor, and the normalized audio data is Output.

The high-frequency normalization circuit 214H is configured to operate in the MD.
The high frequency band audio data decomposed into the signal components on the unit from the CT calculation unit 213 is decomposed into 16 units, and each unit is normalized using a scale factor, and the normalized audio data is Output. Also, the bit distributor 214S is
The components of the audio data in the low frequency band, the middle frequency band, and the high frequency band, which are decomposed into the signal components on the unit from the DCT calculation unit 213, are analyzed, and the analysis result is output. .

At this time, also in the dividing means 21b to 21h, the same processing as that of the dividing means 21a is performed on the audio data of the corresponding channel.

Therefore, the dividing means 21a to 21h output the audio data in the low frequency band, the middle frequency band, and the high frequency band normalized for each unit, and the analysis result of the audio data.

Next, the requantizer 22 shown in FIG. 2 is supplied with the audio data of the low frequency band, the middle frequency band and the high frequency band and the analysis result from the dividing means 21a to 21h. Explain.

As shown in FIG. 2, the requantizer 22 has an input terminal 2 to which the audio data in the low frequency band from the dividing means 21a to 21h are supplied, respectively.
21a to 221h, input terminals 222a to 222h to which the audio data in the middle frequency band from the dividing means 21a to 21h are respectively supplied, and the dividing means 21.
input terminals 223a to 223h to which the audio data of the high frequency band from a to 21h are respectively supplied, input terminals 224a to 224h to which the analysis results from the dividing means 21a to 21h are respectively supplied, and the input Audio data of three frequency bands input via the terminals 221a to 221h, the input terminals 222a to 222h, and the input terminals 223a to 223h is input to the input terminals 224a to 224a.
Based on the analysis result input via 224h, the primary requantizers 225a to 225 that requantize the audio data and obtain the parameter information of the encoding.
h, a requantization evaluator 226 that is a detection unit that detects a common term from the parameter information from the first-order requantizers 225a to 225h and the requantized audio data.
And a secondary requantizer 227 that requantizes at least a part of the common terms detected by the requantization evaluator 226.
a to 227h and the secondary requantizers 227a to 227.
It is composed of parameter information from h and output terminals 228a to 228h for outputting requantized audio data.

The above primary requantizers 225a to 225h.
Is the low frequency range input via the input terminals 221a to 221h, the input terminals 222a to 222h, and the input terminals 223a to 223h, based on the analysis result of the constituent components of the audio data input via the input terminals 224a to 224h. , To determine with what accuracy each unit of audio data normalized for each unit in the middle frequency band and high frequency band is to be encoded, that is, to obtain parameter information and requantize the audio data. It is something to do. Here, when the above-mentioned parameter information is obtained, bit allocation processing is performed based on the block size mode, sub-information amount, and scale factor to determine the word length, so processing can be performed for each channel.

The secondary requantizers 227a to 227h.
Although not shown, a first requantization means for requantizing a common term between channels and a second requantization means for requantizing a common term between sound frames temporally adjacent to each other for each channel. It is composed of a quantizing means and a third requantizing means for requantizing a common term between adjacent units in each band obtained by dividing audio data of a channel into a plurality of frequency bands.

The requantization evaluator 226 detects a common term from the parameter information from the first-order requantizers 225a to 225h and the requantized audio data,
An optimum requantizing means based on the detection result is selected from among the first requantizing means, the second requantizing means, and the third requantizing means of the secondary requantizers 227a to 227h. It is specified by selecting from.

Using the requantization means specified by the requantization evaluator 226, the secondary requantizer 227a is used.
˜227h detect the common term and requantize the common term.

The requantization evaluator 226 will be specifically described.

The requantization evaluator 226, for example, as shown in FIG. 4, the primary requantizers 225a to 225.
The inter-channel detection means 51, which is a first common term detection means for detecting a common term between channels, for the parameter information and the requantized audio data for the 8-channel audio data respectively supplied from h, and for each channel. Between sound frame detecting means 52 which is a second common term detecting means for detecting a common term between sound frames which are temporally adjacent to each other, and between adjacent units in each band obtained by dividing audio data of a channel into a plurality of frequency bands. Inter-unit detection means 53 which is a third common-term detection means for detecting the common term of the
1, an evaluation unit 54 for evaluating the detection results of the sound frame interval detection unit 52, and the unit detection unit 53 using a predetermined evaluation function, and a unit for requantizing based on the evaluation result by the evaluation unit 54. Secondary requantizer 227
a to 227h, a requantization designating unit 55 for designating by selecting from the first requantizing unit, the second requantizing unit, and the third requantizing unit.

The parameter information from the primary requantizers 225a to 225h and the requantized audio data are supplied to the inter-channel detecting means 51, the sound frame inter-detecting means 52, and the inter-unit detecting means 53, respectively. It

The inter-channel detecting means 51 has the above-mentioned 1
In the parameter information from the next requantizers 225a to 225h and the audio data, the common term between the channels is detected, and the detection result is supplied to the evaluation means 54. The sound frame interval detection means 52 detects a common term between sound frames temporally adjacent to each other in the parameter information and audio data from the primary requantizers 225a to 225h, and detects the detection result. It is supplied to the evaluation means 54.

The inter-unit detecting means 53 uses the parameter information from the primary requantizers 225a to 225h and the audio data in common between adjacent units in each band obtained by dividing the audio data of the channel into a plurality of frequency bands. The term is detected, and the detection result is supplied to the evaluation means 54.

The evaluation means 54 detects the common item detected by the inter-channel detecting means 51, the common item detected by the sound frame inter-detecting means 52, and the common item detected by the inter-unit detecting means 53. The detection result and each of the detection results are evaluated using a predetermined evaluation function, and the evaluation result is supplied to the requantization designation unit 55.

The requantization designating means 55 is a means for requantizing based on the evaluation result from the evaluating means 54 as described in 2 above.
The second requantizers 227a to 227h are selected from the first requantization means, the second requantization means, and the third requantization means, and the selection result is selected from the second requantization means 227a to 227a. 227
supply to h respectively.

Here, the secondary requantizers 227a to 227a-2
27h is the requantization evaluator 22 configured as described above.
When the common term is detected using the requantization means designated by No. 6, and the common term is requantized, the second-order requantizers 227a to 227h use the common term to be requantized as audio data. Or the parameter information, the same requantization method is used. Thereby, the requantization process can be simplified. Also, the requantization method in the first requantization means, the second requantization means, and the third requantization means is the same.

This is because the requantization method of this encoding method is
This is because it is performed for each recorded data and does not depend on the relationship with the requantization target data. That is,
In either requantization method, one reference value is determined,
Requantization is performed using the difference from that value.

The quantization method will be specifically described.

For example, as shown in Table 1, when two data values to be requantized are S1 and S2 and S1 is a reference value for comparison, S1 and S2 are the same (S1-S2).
= 0) and the difference between S1 and S2 is +1 (S1-
S2 = + 1), or the difference between S1 and S2 is -1 (S1-
If S2 = −1), the amount of information is compressed by quantizing S2 with short bits. That is, the number of bits of data to be recorded at this time is 1 bit or 3
Become a bit. In addition, even if the difference is the same or +1
Alternatively, if it is not -1, the original S2 data is recorded after recording 2 bits for distinction. That is, the number of bits of data to be recorded at this time is 2 bits +
It becomes the number of bits of S2. The difference calculation as described above is performed by regarding the values of S1 and S2 as unsigned integers, and therefore, regardless of the number of bits of S1 and S2, regardless of the value of S1 and S2, The number of bits may be different. Here, since S1 is a reference value, the difference cannot be quantized.

[0090]

[Table 1]

The first using the quantization method as described above
Which requantization evaluator 226 selects from among the requantization means, the second requantization means, and the third requantization means, the characteristics of the channel, It also depends on the usage environment.

For example, when the correlation of audio data between channels is strong, the above-mentioned primary requantizers 225a to 225 are used.
The data after requantization in h often coincides or is similar. In this case, S1 shown in Table 1 above
And S2, for example, when requantization is performed based on the rule of Table 1 above using parameter information of the same unit with different channels or encoded audio data of the same frequency spectrum, the data to be recorded is 1 bit, Alternatively, the probability of becoming 3 bits becomes high. Therefore, in this case, the requantization evaluator 226 selects and specifies the means for requantizing the common term between the channels, which is the first requantization means.

Further, when the data has a weak correlation between channels, for example, when the same sound tends to continue, the correlation between sound frames becomes strong. Therefore, in this case, the requantization evaluator 226 selects and specifies the means for requantizing the common term between adjacent sound frames for each channel, which is the second requantization means.

Further, when there is a tendency that the voice spectrum is evenly output on the frequency axis, the correlation between the units becomes strong. Therefore, in this case, the requantization evaluator 226 The third requantization means is selected and designated as means for performing a common term between adjacent units in each band obtained by dividing the audio data of each channel into a plurality of frequency bands.

Here, for example, when the common term between channels is requantized with, since the above-mentioned requantization method always requires a comparison reference, at least one of the multi-channels used for input is a channel. It cannot be requantized in between. Also, when re-quantizing the common term between sound frames with, the compressed data does not complete the sound frame, so it is not possible to meet the request for data reproduction from the middle. A sound frame without quantization is required.

Moreover, no correlation is obtained by using any of the first requantization means, the second requantization means, and the third requantization means requantization method, and compression of the information amount can be expected. If there is not, it is necessary to choose not to use this coding method. In this case, it is only a part of the parameter information or the common term of the encoded audio data that the present encoding method is used.

Therefore, in consideration of the above, the requantization evaluator 226 performs a process of selecting a method capable of obtaining the maximum compression rate by using a predetermined evaluation function.

First-order requantizer 2 having the above-mentioned configuration
Requantizer 22 including 25a to 225h, a requantization evaluator 226, and secondary requantizers 227a to 227h.
The operation of will be described.

For example, the primary requantizer 225a inputs from the dividing means 21 via the input terminals 221a to 224a based on the analysis result of the audio data inputted from the dividing means 21 via the input terminal 224. The parameter information of the normalized audio data is obtained for each unit of the three frequency bands, the requantization of the audio data is performed, and the requantized audio data and the parameter information are requantized and evaluated. Vessels 226 and 2
It is supplied to the next requantizer 227a.

At this time, the primary requantizers 225b to 225
Also in h, processing similar to that of the primary requantizer 225a is performed. Therefore, the primary requantizers 225b to 225b
Also from 5h, the parameter information and the requantized audio data are the requantization evaluator 226 and the secondary requantizer 2
27b to 227h, respectively.

The requantization evaluator 226 detects the common term from the parameter information from the first-order requantizers 225b to 225h and the requantized audio data by three common term detecting means, and detects the common term. Optimal requantization means is selected from the three requantization means based on each detection result, and the selection results are supplied to the secondary requantizers 227b to 227h as requantization means selection information. To do.

The secondary requantizers 227b to 227h.
Is the parameter information from the primary requantizers 225a to 225h and the requantized audio data based on the selection result from the requantization evaluator 226 between channels, between sound frames, Alternatively, a common term is detected between units and the common term is requantized. Then, the secondary requantizers 227b to 227h.
Outputs the requantized data to output terminals 228a to 228a.
Output via 8h.

Therefore, as described above, the first, second, and
By selecting the third requantization means using a predetermined evaluation function and performing requantization for each frequency band, it is possible to more effectively compress the amount of information that matches the frequency characteristics of the audio data. . That is, this makes it possible to suppress redundant recording.

That is, the operation of the common channel encoder 2 shown in FIG. 2 will be described. First, the dividing means 21a to 21h divide the sampled and quantized audio data into three frequency bands. Further, the audio data is decomposed into signal components on a block floating unit of time and frequency, and is normalized by using a scale factor for each unit. The dividing means 21a to 21h analyze the audio data and supply the requantizer 22 with the analysis result and the audio data of three frequency bands normalized for each unit.

The requantizer 22 includes the dividing means 21.
The audio data of the three frequency bands from a to 21h are requantized and parameter information is obtained based on the analysis result from the dividing means 21a to 21h. Further, the requantizer 22 detects a common term from the quantized audio data and the parameter information, selects a means for requantizing the common term, and selects a channel, a sound frame, or a sound frame. , Requantize the common term between units. Then, the requantizer 22 supplies the parameter information and the requantized spectrum data to the formatters 23a to 23h, respectively.

The formatters 23a to 23h transmit the parameter information from the requantizer 22 and the requantized spectrum data according to a predetermined format for transmission or recording on a recording medium. Assemble and output to a stream.

Therefore, in the high efficiency coding apparatus according to the present invention, the common channel encoder 2 shown in FIG. 1 requantizes the common term as described above. Then, the requantized audio data is supplied to the multiplexer 3 and is combined into one data by the multiplexer 3. The data collected as one is output via the force terminal 4.

Here, the data format output from the output terminal 4 is, for example, as shown in FIG. 5, from the top, the ID data 90 of 20 bytes and the data 91 to 91 of channels Ch1 to Ch8 of 212 bytes each. The CRC data 99 is an error correction code of 98 bytes and 4 bytes.

The encoding process in the common channel encoder 2 is performed in units of sound frames, and one sound frame consists of 212 bytes. In this 1 sound frame, 512 samples of 14.1 channel audio reproduction data are compression-encoded at a sampling grade of 44.1 kHz.

The data in the sound frame will be described below.

The data format in the sound frame is as shown in FIG.
1, sub information amount 82, word length data 83, scale factor data 84, spectrum data 85, redundant scale factor data 86, redundant word length data 87, lower sub information amount 88, and lower block size mode 89. There is.

Here, the redundant scale factor data 86
, Redundant word length data 87, lower sub information amount 88, and lower block size mode 89
Are double-written portions for error correction.

The block size mode 81 is data for recording the evaluation result in the block size evaluator 213S of the MDCT operation unit 213 shown in FIG. For example, as shown in Table 2, in the long mode,
In the low frequency band and the mid frequency band, the low frequency MDCT circuit 31 and the mid frequency MDCT circuit 3 of the MDCT calculation unit 3
2 is divided into 128 frequency components, respectively, and
In the high frequency band, the high frequency MD of the MDCT calculator 3
It is divided into 256 frequency components by the CT circuit 33. In the short mode, the low frequency band, the middle frequency band, and the high frequency band are the low frequency band MDCT circuit 31 and the middle frequency band MDC.
It is divided into 32 frequency components by the T circuit 32 and the high frequency MDCT circuit 33.

[0114]

[Table 2]

Further, the sub information amount 82
As shown in Table 3, amount 1, amount 2,
Three pieces of information of the amount 3 are recorded. The amount 1 represents the number of the recorded word length data 83 and scale factor data 84, and the amount 2 is the double written word length data 83.
, And the amount 3 represents the number of double-written scale factor data 84.

[0116]

[Table 3]

As shown in Table 4, the word length data 83 represents the word length of each unit when requantized.

[0118]

[Table 4]

The scale factor data 84 represents the normalized value of each unit, as shown in Tables 5 and 6.

[0120]

[Table 5]

[0121]

[Table 6]

As described above, in the present invention, in encoding multi-channel audio data, the common term is detected from the encoded audio data and the parameter information of the encoding, and at least a part of the common term is detected. Since requantization is performed, a higher compression rate can be realized than existing compression encoding. Further, the means for requantizing is selected by using a predetermined evaluation function, and in order to requantize the common term between channels, between sound frames, or between units, it is more effective than existing compression coding. A high compression rate can be realized.

Further, since the requantization is performed for each band obtained by dividing the audio data of each channel into a plurality of frequency bands, it is possible to perform the encoding according to the frequency characteristic of the audio data.

The data coded by the high-efficiency coding apparatus according to the present invention described above is of the existing compression coding system in which at least a part of the common term of the parameter information or the coded data is requantized. The data. That is, when reproducing the encoded data, when the data collected at the time of recording is divided into channels, the data of one common item is simply distributed to the corresponding channels to perform decoding by the existing decoding device. Can be realized.

[0125]

The high-efficiency encoding method for multi-channel audio data according to the present invention is a high-efficiency encoding method for encoding digital audio data of a plurality of channels and obtaining parameter information for the encoding. , A common term is detected from the encoded audio data and the parameter information, and at least a part of the common term is requantized. As a result, high compression can be realized by using the correlated digital audio data. In addition, when reproducing the data encoded by the high efficiency encoding method, the existing decoding device can be used.

Further, in the high-efficiency coding method for multi-channel audio data according to the present invention, the common term between the channels is detected and the common term between the channels is requantized. As a result, high compression can be realized by utilizing the correlation of digital audio data between channels. In addition, when reproducing the data encoded by the high efficiency encoding method, the existing decoding device can be used.

Further, in the high-efficiency encoding method for multi-channel audio data according to the present invention, a common term is detected between sound frames temporally adjacent to each other for each channel, and the common term between the sound frames is requantized. To do.
As a result, high compression can be realized by utilizing the correlation between sound frames. Therefore, high compression can be realized regardless of the degree of correlation of digital data between multi-channels. In addition, when reproducing the data encoded by the high efficiency encoding method, the existing decoding device can be used.

Further, in the high-efficiency encoding method for multi-channel audio data according to the present invention, the common term is detected between the adjacent units of each band obtained by dividing the digital audio data of the channel into a plurality of frequency bands, and the inter-units are detected. Requantize the common term of. As a result, high compression can be realized by utilizing the correlation between units. Therefore, high compression can be realized regardless of the degree of correlation of digital data between multi-channels. In addition, when reproducing the data encoded by the high efficiency encoding method, the existing decoding device can be used.

Further, in the high-efficiency encoding method for multi-channel audio data according to the present invention, the common term between the channels and the common term between the sound frames temporally adjacent to each other and the digital audio data of the channels are transmitted in plural frequencies. The common term between adjacent units of each band divided into bands is detected. Each detection result is evaluated using a predetermined evaluation function. Further, based on the evaluation result, a first requantization method for requantizing at least a part of common terms between channels and at least one of common terms between sound frames temporally adjacent to each channel. And a third requantization method for requantizing at least a part of common terms between adjacent units in each band obtained by dividing digital audio data of a channel into a plurality of frequency bands. Specify the requantization method from the quantization methods. When the first requantization method is designated, at least part of the common term between channels is requantized. When the second requantization method is specified,
At least a part of the common term between the sound frames temporally adjacent to each other is requantized. Also, the third
When the re-quantization method is specified, at least a part of common terms between adjacent units of each band obtained by dividing the digital audio data of the channel into a plurality of frequency bands is re-quantized. As a result, when requantization is performed by the first quantization method, high compression can be realized by utilizing the correlation of digital audio data between channels, and requantization by the second quantization method is possible. When the quantization is performed, the high compression can be realized by utilizing the correlation of the digital audio data between the sound frames, and when the requantization is performed by the third quantization method, the digital compression between the units can be performed. High compression can be realized by utilizing the correlation of audio data. Therefore, high compression can be realized regardless of the degree of correlation of digital data between multi-channels. In addition, when reproducing the data encoded by the high efficiency encoding method, the existing decoding device can be used.

In the high-efficiency coding apparatus for multi-channel audio data according to the present invention, digital audio data of a plurality of channels are coded, the coded audio data is output, and the parameter information for the coding is output. In the high-efficiency coding device, the primary requantization means requantizes the audio data and generates parameter information for the coding. The detecting means detects a common term from the audio data requantized by the primary requantizing means and the parameter information. The secondary requantization means requantizes at least a part of the common term detected by the detection means. As a result, high compression can be realized by using the correlated digital audio data. Also, when reproducing the data encoded by the high efficiency encoding device, the existing decoding device can be used.

Further, in the high-efficiency coding apparatus for multi-channel audio data according to the present invention, the detecting means detects a common term between channels. The secondary requantization means requantizes the common term between channels. As a result, high compression can be realized by utilizing the correlation between channels. Also, when reproducing the data encoded by the high efficiency encoding device, the existing decoding device can be used.

Further, in the high-efficiency coding apparatus for multi-channel audio data according to the present invention, the detecting means detects a common term between sound frames which are temporally adjacent to each other for each channel. The secondary requantization means requantizes the common term between sound frames that are temporally adjacent to each other for each channel. As a result, high compression can be realized by utilizing the correlation between sound frames.
Therefore, high compression can be realized regardless of the degree of correlation of digital data between multi-channels. Also, when reproducing the data encoded by the high efficiency encoding device, the existing decoding device can be used.

In the high-efficiency coding apparatus for multi-channel audio data according to the present invention, the detecting means detects a common term between adjacent units in each band obtained by dividing the digital audio data of the channel into a plurality of frequency bands. To do. The secondary requantization means requantizes the common term between adjacent units in each band obtained by dividing the digital audio data of each channel into a plurality of frequency bands.
As a result, high compression can be realized by utilizing the correlation between units. Therefore, high compression can be realized regardless of the degree of correlation of digital data between multi-channels. Also, when reproducing the data encoded by the high efficiency encoding device, the existing decoding device can be used.

In the high-efficiency coding apparatus for multi-channel audio data according to the present invention, the first re-quantization means of the secondary re-quantization means re-quantizes the common term between the channels. The second requantization means of the second-order requantization means requantizes the common term between sound frames temporally adjacent to each other for each channel. The third requantization means of the second-order requantization means requantizes the common term between the adjacent units of each band obtained by dividing the digital audio data of the channel into a plurality of frequency bands. The first common term detecting means of the detecting means detects a common term between channels. The second common term detecting means of the detecting means detects a common term between sound frames that are temporally adjacent to each other for each channel. The third common term detecting means of the detecting means detects a common term between adjacent units in each band obtained by dividing the digital audio data of the channel into a plurality of frequency bands. The evaluation means of the detection means evaluates the detection results of the common terms of the first common term detection means, the second common term detection means, and the third common term detection means, respectively, using a predetermined evaluation function. The requantization designation means of the detection means includes means for requantizing based on the evaluation result by the evaluation means, the first requantization means, the second requantization means, and the third requantization means. Select and specify from among the means of conversion. Thereby, when the first quantizing means is selected, high compression can be realized by utilizing the correlation of the digital audio data between the channels, and when the second quantizing means is selected. , High compression can be realized by utilizing the correlation of the digital audio data between the sound frames, and by utilizing the correlation of the digital audio data between the units when the third quantizing means is selected. High compression can be realized. Therefore, high compression can be realized regardless of the degree of correlation of digital data between multi-channels. Also,
When reproducing the data encoded by the high-efficiency encoder, the existing decoder can be used.

[Brief description of drawings]

FIG. 1 is a diagram showing a schematic configuration of a high efficiency encoding device according to the present invention.

FIG. 2 is a diagram showing a configuration of a common channel encoder shown in FIG.

FIG. 3 is a diagram showing a configuration of a dividing unit shown in FIG.

FIG. 4 is a diagram showing a configuration of a secondary requantizer shown in FIG.

FIG. 5 is a diagram showing a state of recording on a recording medium of data obtained by encoding 8-channel audio data by a 1/5 compression method.

FIG. 6 is a diagram for explaining a state of recording encoded data in a sound frame.

FIG. 7 is a plan view schematically showing the structure of a motion picture film.

FIG. 8 is a diagram schematically showing a configuration of an 8-channel digital sound system.

[Fig. 9] Fig. 9 is a diagram illustrating a configuration for performing processing of collecting 8-channel encoded audio data into one data without changing the audio data.

[Explanation of symbols]

 1a to 1h Input terminal 2 Common channel encoder 3 Multiplexer 4 Output terminal 21a to 21h Dividing means 22 Requantizer 23a to 23h Formatter 51 Inter-channel detecting means 52 Sub-frame detecting means 53 Inter-unit detecting means 54 Evaluation means 55 Re Quantization designation means 212 Band division filter 213 MDCT operation unit 213L Low band MDCT circuit 213M Mid band MDCT circuit 213H High band MDCT circuit 213S Block size evaluator 214 Unit processing unit 214L Low band normalization circuit 214M Mid band normalization circuit 214H High Area normalization circuit 214S bit allocation unit 225a to 225h primary requantizer 226 requantization evaluator 227a to 227h secondary requantizer

Claims (10)

[Claims] 1. A high-efficiency encoding method for encoding digital audio data of a plurality of channels and obtaining parameter information of the encoding, wherein a common term from the encoded audio data and the parameter information. Is detected and at least part of the common term is requantized, and a high-efficiency encoding method for multi-channel audio data. 2. The high-efficiency coding method for multi-channel audio data according to claim 1, wherein a common term is detected between channels and the common term between the channels is requantized. 3. The multi-channel audio data according to claim 1, wherein a common term is detected between sound frames that are temporally adjacent to each other for each channel, and the common term between the sound frames is requantized. High efficiency coding method. 4. The common term between adjacent units in each band obtained by dividing the digital audio data of the channel into a plurality of frequency bands is detected, and the common term between the units is requantized. A method for high-efficiency encoding of multi-channel audio data as described. 5. A common term between channels, a common term between sound frames temporally adjacent to each other, and a common term between adjacent units of each band obtained by dividing digital audio data of a channel into a plurality of frequency bands. A first requantization method of requantizing at least a part of common terms between channels, each of which is detected, each detection result is evaluated using a predetermined evaluation function, and based on the evaluation result; A second requantization method for requantizing at least a part of common terms between sound frames that are temporally adjacent to each other for each channel, and digital audio data of each channel is divided into multiple frequency bands and adjacent Characterized in that the common term is requantized by designating a requantization method from among a third requantization method of requantizing at least a part of the common term between units. The high-efficiency encoding method for multi-channel audio data according to claim 1. 6. A high-efficiency encoder which encodes digital audio data of a plurality of channels, outputs the encoded audio data, and outputs the encoding parameter information. Primary requantization means for requantizing and generating parameter information for the encoding, detection means for detecting a common term from the audio data requantized by the primary requantization means and parameter information, and And a secondary requantization unit for requantizing at least a part of the common terms detected by the detection unit. 7. The multi-channel according to claim 6, wherein the detecting means detects a common term between channels, and the secondary requantization means requantizes a common term between channels. High-efficiency encoder for audio data. 8. The detecting means detects a common term between sound frames that are temporally adjacent to each other for each channel, and the secondary requantization means is for detecting a common term between sound frames that are temporally adjacent to each other for each channel. 7. The high-efficiency coding apparatus for multi-channel audio data according to claim 6, wherein the common term is requantized. 9. The detecting means detects a common term between adjacent units of each band obtained by dividing the channel digital audio data into a plurality of frequency bands, and the secondary requantization means detects the channel digital audio data. 7. The high-efficiency coding apparatus for multi-channel audio data according to claim 6, wherein common terms between adjacent units of each band divided into a plurality of frequency bands are requantized. 10. The second-order requantization means requantizes common terms between sound frames temporally adjacent to each other, and first requantization means for requantizing common terms between channels. Second requantizing means for converting the digital audio data of the channel into a plurality of frequency bands, and third requantizing means for requantizing a common term between adjacent units of each band, The detection means includes first common term detection means for detecting a common term between channels, second common term detection means for detecting a common term between sound frames temporally adjacent to each other, and Third common term detecting means for detecting a common term between adjacent units in each band obtained by dividing the digital audio data into a plurality of frequency bands, the first common term detecting means and the second common term detecting means. The first requantization means for evaluating the common term detection result of the third common term detection means by using a predetermined evaluation function, and the requantization means for requantizing based on the evaluation result by the evaluation means. 7. The multi-channel audio data according to claim 6, further comprising: a means, a second requantization means, and a requantization designating means for designating by selecting from the third requantization means. High efficiency encoder.