JP2001195092A - Voice coding device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve a compression rate when voice signals in a plurality of channels are subjected to predictive coding using the fact that the correlation among the upper bit data of each channel of voice signals of the plurality of channels is strong and no correlation exists among the lower bit data. SOLUTION: An adding circuit 1a computes the sum signal (L+R) of stereophonic 2ch signals L and R and outputs the signal to a single ch lossless/encoder 2D1 of a sum ch. A subtracting circuit 1b computes the difference signal (L-R) and outputs the signals to a single ch lossless/encoder 2D2 of a difference ch. The encoders 2D1 and 2D2 conduct predictive coding of the signals (L+R) of upper 16 bits, difference Δ(L+R) of the difference signals (L-R) and the Δ(L-R) among 24 bits, and lower 8 bits are transferred as they are through a recording medium or a communication medium.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a speech coding apparatus for predictively coding and compressing a speech signal.

[0002]

2. Description of the Related Art As a method for encoding a speech signal with high efficiency, for example, a Huffman code is known as disclosed in Japanese Patent Application Laid-Open No. 58-75341. As a method for predictive coding of an audio signal, the present inventor has proposed in a prior application (Japanese Patent Application No. 9-289159) that a plurality of predictors having different characteristics are used for a one-channel original digital audio signal in a time domain. Calculating a plurality of linear prediction values of the current signal from the past signal in, calculating a prediction residual for each predictor from the original digital audio signal and the plurality of linear prediction values, and calculating a minimum value of the plurality of prediction residuals Suggests how to choose.

[0003]

However, in the above method, the original digital audio signal has a sampling frequency = 96.
In the case of kHz and the number of quantization bits = about 20 bits, a certain compression effect can be obtained.
Audio discs use twice this sampling frequency (= 192 kHz), and the number of quantization bits tends to use 24 bits. Therefore, it is necessary to improve the compression ratio.

Incidentally, in order to enable reproduction by both a simple model such as a CD reproducing apparatus and a higher model such as a DVD reproducing apparatus, for example, Japanese Patent Laid-Open No. 9-31206 is disclosed.
No. 6, as shown in Japanese Patent Publication No. 6
A method has been proposed in which sample data of 0 bits (or 24 bits) is separated into upper 16 bits and lower 4 bits (or 8 bits) which can be reproduced by a simple model and transmitted.

Accordingly, the present invention considers the fact that there is a strong correlation between the upper bit data of each channel of the audio signal of a plurality of channels (channels) and there is no correlation between the lower bit data, so that the audio signal of the plurality of channels (channels) is It is an object of the present invention to provide a speech encoding device capable of improving a compression ratio when performing predictive encoding.

[0006]

In order to achieve the above object, the present invention comprises the following means (1) and (2).
That is,

1) Correlation means for converting digital audio signals of a first plurality of channels having the same sampling frequency and composed of two systems into audio signals of a plurality of second channels mutually correlated by a predetermined matrix operation. And separating means for separating the audio signals of the second plurality of channels into higher-order bits and lower-order bit data as needed for each channel, and, when separated by the separating means, separates the higher-order bit data for each channel. Prediction in response to input data, obtaining a first sample value, and selecting a linear prediction method that minimizes a prediction residual among a plurality of prediction values of a current signal from a past signal in a time domain. Encoding means; first sample value of each channel selected by the predictive encoding means; prediction residual; and prediction data including a linear prediction method; Speech encoding apparatus and a means for multiplexing the low-order bit data and the separation flag in a predetermined format, when it is separated by. 2) correlating means for converting digital audio signals of a first plurality of channels having the same sampling frequency and composed of two systems into audio signals of a plurality of channels correlated with each other by a predetermined matrix operation; The second plurality of channels of the converted audio signal, in response to the audio signal input for each channel, to obtain the first sample value, from a plurality of predicted values of the current signal from the past signal in the time domain A predictive encoding unit that selects and predictively codes a linear prediction method that minimizes the prediction residual; and includes a head sample value, a prediction residual, and a linear prediction method of each channel selected by the predictive encoding unit. Means for multiplexing the predicted data in a predetermined format.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing a first embodiment of an audio encoding device and a corresponding audio decoding device according to the present invention, FIG. 2 is a block diagram showing the encoder of FIG. 1 in detail, and FIG. 3 is a DVD pack format. FIG. 4 is an explanatory diagram showing the format of a DVD audio pack, and FIG. 5 is a block diagram showing the decoder of FIG. 1 in detail.

The channel correlation circuit A shown in FIG. 1 has an addition circuit 1a and a subtraction circuit 1b. In the addition circuit 1a, each channel (hereinafter, ch) has a sampling frequency of 192 k
Calculates the sum signal (L + R) of the stereo 2ch signals L and R with the frequency and the number of quantization bits = 24 bits and outputs the sum signal to the 1ch lossless encoder 2D1 for the sum channel, and the subtraction circuit 1b calculates the difference signal (LR). The calculated value is output to the 1ch lossless encoder 2D2 for the difference channel. As shown in detail in FIG. 2, the encoders 2D1 and 2D2 each have the upper 16 bits of 24 bits.
Difference Δ between bit sum signal (L + R) and difference signal (L−R)
(L + R) and Δ (LR) are predictively coded,
The lower 8 bits are directly transmitted via a recording medium or a communication medium.

When the original data is 20 bits, the number of upper bits is fixed, and the number of lower bits is made variable to separate the upper 16 bits and lower 4 bits. When the original data is 16 bits, the 16-bit data is predictively encoded without separation.

On the decoding side, as shown in detail in FIG. 6, the decoders 3D1 and 3D2 respectively include the upper 16 bits of each channel.
The bits of the prediction coded data are decoded into a sum signal (L + R) and a difference signal (LR), and the lower 8 bits are added to the 16-bit data to restore the original 24-bit data. Next, the channel correlation circuit B restores the 24-bit sum signal (L + R) and difference signal (LR) to stereo 2-ch signals L and R.

Referring to FIG. 2, encoders 2D1, 2D2
Will be described in detail. The sum signal (L + R) and the difference signal (LR) are stored in one frame buffer 10 for each frame. Then, the sample values (L + R) and (LR) of the upper 16 bits of one frame are applied to the difference calculation circuits 11D1 and 11D2, respectively, and the difference Δ (L + R), Δ (LR) between the current and previous times is calculated. That is, the difference PCM (D
PCM) data is calculated. Also, 24-bit data (L + R), (LR) of the first sample of each frame.
And the lower 8-bit data (L + R) of each sample, (L
−R) is applied to the multiplexer 19.

The difference Δ (L + R) calculated by the difference calculation circuit 11D1 is calculated by a plurality of predictors 12 having different prediction coefficients.
a-1 to 12a-n and subtracters 13a-1 to 13a-n. Then, the predictors 12a-1 to 12a-n calculate the respective predicted values of the difference Δ (L + R) based on the respective prediction coefficients, and the subtractors 13a-1 to 13b-n calculate the respective predicted values and the difference Δ Each prediction residual of (L + R) is calculated. The buffer / selector 16D1 temporarily stores the plurality of prediction residuals, selects the minimum prediction residual for each subframe specified by the selection signal generator 17, and outputs the selected prediction residual to the packing circuit 18. Note that this subframe has a sample length of about one-tenth of a frame, and one frame is, for example, 80 subframes. here,
Predictors 12a-1 to 12a-n and subtracters 13a-1 to 13a-1
3a-n constitute a prediction circuit 15D1 for the sum signal ch, and the prediction circuit 15D1 and the buffer / selector 16D1
Constitutes a predictive encoding circuit for the sum signal ch.

Similarly, the difference Δ (LR) calculated by the difference calculation circuit 11D2 is calculated by a plurality of predictors 12b-1 to 12b-n and subtracters 13b-1 to 13b-13 having different prediction coefficients.
b-n. Then, the predictors 12b-1 to 12b-12
bn, the difference Δ (L−
R) are calculated, and the subtractors 13b-1 to 13b
In −n, each prediction residual of the difference Δ (LR) from each of the prediction values is calculated. The buffer / selector 16D2 temporarily stores the plurality of prediction residuals, and
The minimum prediction residual is selected for each sub-frame specified by, and is output to the packing circuit 18. Predictor 12b-
1 to 12b-n and the subtractors 13b-1 to 13b-n form a prediction circuit 15D2 for the difference signal ch, and the prediction circuit 15D2 and the buffer / selector 16D2 form a prediction encoding circuit for the difference signal ch. are doing.

The selection signal generator 17 applies a bit number flag of the prediction residual to the packing circuit 18 and the multiplexer 19, and outputs a predictor selection flag indicating the predictor having the minimum prediction residual to the multiplexer 19. To apply.
The packing circuit 18 includes buffer / selectors 16D1, 16D.
The prediction residual for 2 ch selected by D2 is packed with the specified number of bits based on the bit number flag specified by the selection signal generator 17.

The following multiplexer 19 provides a frame header for the upper 16-bit data of one frame; a separation flag 120 indicating whether or not the original 24-bit data has been separated into the upper 16 bits and the lower 8 bits; A head sample value of one frame of the sum signal ch (L + R); a head sample value of one frame of the difference signal ch (LR); and a predictor selection flag for each subframe of the sum signal ch (L + R). A predictor selection flag for each sub-frame of the difference signal ch (LR); a bit number flag for each sub-frame of the sum signal ch (L + R); A bit number flag for each frame; a prediction residual data sequence (variable number of bits) of the sum signal ch (L + R); and a prediction residual data sequence (variable number of bits) of the difference signal ch (LR). , Many However, output as a variable rate bit stream.

The lower 8 bits that have not been predictively coded are output as another bit stream.
According to such predictive coding, when the original signal has, for example, a sampling frequency of 192 kHz, a quantization bit number of 24 bits, and two channels, a compression rate of 57% on average can be realized.

When recording the variable rate bit stream data on a DVD audio disc,
It is packed in the audio (A) pack of the compressed PCM shown in FIG. This pack has 4 bytes of pack start information for 2034 bytes of user data (A packet and V packet) and 6 bytes of SCR (System Clock).
Reference: system time reference value, 3-byte Mux rate (rate) information, and 1-byte stuffing for a total of 14-byte pack header (1 pack = 2048 bytes in total). In this case, the time of the A pack in the same title can be managed by setting the SCR information as the time stamp to be “1” in the first pack in the ACB unit so as to be continuous in the same title.

As shown in detail in FIG.
7, 9 or 14 byte packet header and compressed PCM
, And 1 to 2011 bytes of audio-compressed PCM data in the above format, and upper 16-bit data and lower 8-bit data are contained in another A packet. The private header of the compressed PCM is: 1-byte substream ID, 2 bytes of UPC / EAN-ISRC (Universal Prism).
oduct Code / European Article Number-International S
tandard Recording Code) number and UPC / EAN-
ISRC data, 1-byte private header length, 2 bytes of first access unit pointer, 8 bytes of audio data information (ADI), and 0 to 7 bytes of stuffing bytes. I have.

Next, the decoders D1 and D2 will be described with reference to FIG. The variable-rate bit stream data in the format described above is separated by the demultiplexer 21 based on the frame header. Then, the leading sample values of one frame of the sum signal ch (L + R) and the difference signal ch (LR) are calculated by the accumulator circuits 25a and 25, respectively.
b, the sum signal ch (L + R) and the difference signal ch
The predictor selection flags of (LR) are the predictors (24
a-1 to 24a-n) and (24b-1 to 24b-n) are applied as selection signals, and the bit number flags and the prediction residual data of the sum signal ch (L + R) and the difference signal ch (LR). The columns are applied to an unpacking circuit 22. Further, when the variable-rate bit stream data includes lower-order bit data, the lower-order bit data is separated and applied to the adders 28a and 28b, and the separation flag is applied as a control signal to the adders 28a and 28b. .

Here, the predictors (24a-1 to 24a-
n) and (24b-1 to 24b-n) are predictors (12a-1 to 12a-n) and (12b-1) on the encoding side, respectively.
To 12b-n), and those having the same characteristics are selected by the predictor selection flag.

The unpacking circuit 22 outputs the sum signal ch (L
+ R) and the prediction residual data sequence of the difference signal ch (LR) are separated based on the bit number flags and output to the adders 23a and 23b, respectively. The adder circuits 23a and 23b respectively add the sum signal ch from the unpacking circuit 22.
(L + R) and the current prediction residual data of the difference signal ch (LR), and the predictors (24a-1 to 24a-n), (24
b-1 to 24b-n), the previous predicted value predicted by each one selected by the predictor selection flag is added to calculate the current predicted value. This forecast is
The differences Δ (L + R) and Δ (LR) calculated by the difference calculation circuits 11D1 and 11D2 shown in FIG. 2, that is, DPCM data, are the predictors (24a-1 to 24a).
-N), (24b-1 to 24b-n) and the cumulative operation circuit 2
5a and 25b.

The accumulator circuits 25a and 25b are respectively
The difference Δ (L +
R) and Δ (LR) are cumulatively added for each sample, and the PCM data (upper 16-bit data) of the sum signal ch (L + R) and the difference signal ch (LR) are respectively added to the adder 28a.
28b. The adders 28a and 28b output the sum signal ch (L + R) when the separation flag is "separated".
The upper 16-bit PCM data of each of the difference signals ch (LR) and the lower-bit PCM data separated by the demultiplexer 21 are added and output. On the other hand, when the separation flag is "no separation", the upper 16 bits are output. The bit PCM data is output as it is.

The sum signal (L + R) and the difference signal (LR)
As shown in FIG. 1, the 2L signal is calculated by the addition circuit 4a and the 2R signal is calculated by the subtraction circuit 4b. Then, the 2L signal and the 2R signal are divided by 1/2 by the dividers 5a and 5b, respectively, and the original stereo 2
The channel signals L and R are restored.

Next, a second embodiment will be described with reference to FIGS. In the above embodiment, the sum signal (L +
R), each difference Δ (L + R), Δ (L) of the difference signal (LR)
-R), that is, predictive encoding is performed only on the DPCM data. In the second embodiment, the sum signal (L + R), the difference signal (LR), ie, the PCM data, or each difference Δ (L + R), Δ (LR), that is, DPCM data is selectively and predictively encoded.

For this reason, the encoding apparatus shown in FIG.
The sum signal (L + R) and the difference signal (L−
R) for predictive encoding, respectively.
15S and buffer / selectors 16A and 16S are added. The selection signal generator 17 is a buffer / selector 1
6A, the sum signal (L +
R), the difference signal (LR) and the buffer / selector 16D
1, ΔD (L +
R), Δ (LR) based on the minimum value of each prediction residual.
It is determined whether the compression ratio of PCM data or DPCM data is higher, and the higher data is selected. At this time, the PCM / DPCM selection flag (prediction circuit selection flag) is added and multiplexed.

Here, the prediction circuit 15A for the sum signal (L + R) and the prediction circuit 15D1 for the difference Δ (L + R) shown in FIG. 6 have the same configuration, and the prediction circuit 15S for the difference signal (L−R) has the same configuration. If the difference Δ (LR) prediction circuits 15D2 have the same configuration, the decoding apparatus uses the PCM as shown in FIG.
It is not necessary to provide a prediction circuit for both data and DPCM data, and a prediction circuit for one data may be used. Then, based on the prediction circuit selection flag transmitted from the encoding device, the selectors 26a and 26b select the outputs of the accumulator circuits 25a and 25b in the case of DPCM data.
In the case of M data, the outputs of the adders 23a and 23b are selected. Then, the upper 16-bit data and lower bit data of each channel selected by the selectors 26a and 26b are added by the adders 28a and 28b.

In the third embodiment, as shown in FIG. 8, the original signals L and R (PCM data), the sum signal (L + R), the difference signal (LR) (PCM data), and each difference Δ (L
+ R) and one of the three groups Δ (LR) (DPCM data) are selectively predictively encoded.

For this reason, the encoding apparatus shown in FIG.
In addition to the configuration shown in (1), prediction circuits 15L and 15R for predictively encoding the original signals L and R, and buffers / selectors 16L and 16R are added. Further, the selection signal generator 17 includes the original signals L and R selected by the buffer / selectors 16L and 16R and the buffer / selectors 16A and 16S.
Signal (L + R), difference signal (LR) selected by
And data of a group having a high compression rate based on the minimum values of the prediction residuals of the differences Δ (L + R) and Δ (LR) selected by the buffer / selectors 16D1 and 16D2. At this time, the selection flag (prediction circuit selection flag) is added and multiplexed.

When the three groups of prediction circuits shown in FIG. 8 have the same configuration, the decoding device does not need to provide three groups of prediction circuits as shown in FIG. Is fine. Then, based on the prediction circuit selection flag transmitted from the encoding device, the output of the accumulation operation circuits 25a and 25b is selected in the case of DPCM data, and the output of the addition circuits 23a and 23b is selected in the case of PCM data. The original signals L and R are
(Upper 16-bit data). Further, the selectors 27a and 27b select the outputs of the adders 23a and 23b in the case of the group of the original signals L and R, and select the output of the channel correlation circuit B in other cases. Next, the upper 16-bit data and lower bit data of each channel selected by the selectors 27a and 27b are added by the adders 28a and 28b.

In the first to third embodiments,
Although the case where the original signal has two channels has been described, the present invention can also be applied to the case of a multi-channel signal. Here, the following four systems are known as multi-channel systems. (1) Dolby Surround System 3 channels of front L, C, R + 1 channel of rear S in total 4 channels (2) Dolby AC-3 system 4 channels of front L, C, R, SW + rear SL, SR 6 channels in total of 2 channels (3) DTS (Digital Theater System) system 6 channels (L, C,
R, SW, SL, SR) (4) Sony Dynamic Digital Sound (SDDS) system: 6 channels of front L, LC, C, RC, R, SW + rear SL, 2 channels of SR, totaling 8 channels

Therefore, the correlation circuit A shown in FIG. 1 uses a 5-channel PCM of left (L), center (C), right (R), surround left (SL) and surround right (SR) as an example of a multi-channel signal. The data is L
The channel is converted into the following 5 channels (L) and (D1) to (D4) based on the channel. L = L (reference channel) D1 = C-(L + R) / 2 D2 = R-L D3 = SL-a x L D4 = SR-b x R where 0 ≤ a, b ≤ 1

Then, each channel data of the 5 channels is separated into upper 16 bits and lower bits, the upper 16 bits data is predictively encoded and transmitted, and the lower bit data is transmitted as it is. When obtaining the correlation, the correlation may be converted to the next 5 channels. L = L (reference channel) D1 = CL-D2 = RL-D3 = SL-LD4 = SR-R

When the variable-rate bit stream data that has been predictively coded by the coding side is transmitted through a network, the coding side packetizes the data for transmission as shown in FIG. A header is added (step S42), and the packet is sent out to the network (step S43). On the decoding side, the header is removed as shown in FIG.
51) Then, the data is restored (step S52), and the data is stored in the memory and decoding is waited (step S53).

[0035]

As described above, according to the present invention, audio signals of a plurality of channels are separated into upper bit data and lower bit data for each channel, and the upper bit data is predictively coded. It is possible to improve the compression ratio when predictive coding is performed on audio signals of a plurality of channels.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a first embodiment of a speech encoding apparatus according to the present invention and a speech decoding apparatus corresponding thereto.

FIG. 2 is a block diagram showing the encoder of FIG. 1 in detail.

FIG. 3 is an explanatory diagram showing a format of a DVD pack.

FIG. 4 is an explanatory diagram showing a format of a DVD audio pack.

FIG. 5 is a detailed block diagram illustrating the decoder of FIG. 1;

FIG. 6 is a block diagram illustrating an encoder according to a second embodiment.

FIG. 7 is a block diagram illustrating a decoder according to a second embodiment.

FIG. 8 is a block diagram illustrating an encoder according to a third embodiment.

FIG. 9 is a block diagram illustrating a decoder according to a third embodiment.

FIG. 10 is a flowchart showing a voice transmission method.

FIG. 11 is a flowchart showing a voice transmission method.

[Explanation of symbols]

1a Addition circuit (addition means) 1b Subtraction circuit (subtraction means) 10 1 frame buffer (separation means) 11D1 Difference calculation circuit (first difference calculation means) 11D2 Difference calculation circuit (second difference calculation means) 12a-1 12a-n predictor (subtractors 13a-1 to 13a-1)
13a-n and the buffer / selector 16D1 constitute a first predictive encoding means. ) 12b-1 to 12b-n predictors (subtractors 13b-1 to 13b-1)
13b-n and the buffer / selector 16D2 constitute a second predictive encoding means. 13a-1 to 13a-n, 13b-1 to 13b-n Subtractors 16D1, 16D2, 16A, 16S, 16L, 16R
Buffer / selector 15A Prediction circuit (third with buffer / selector 16A)
Of predictive encoding means. ) 15S prediction circuit (4th with buffer / selector 16S)
Of predictive encoding means. ) 15L prediction circuit (fifth with buffer / selector 16L)
Of predictive encoding means. ) 15R prediction circuit (6th with buffer / selector 16R)
Of predictive encoding means. 19) Multiplexer (multiplexing means) A Correlation circuit (correlation means)

────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] February 7, 2001 (2001.2.7)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Claims

[Correction method] Change

[Correction contents]

[Claims]

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0007

[Correction method] Change

[Correction contents]

1) Correlation means for converting digital audio signals of a first plurality of channels having the same sampling frequency and composed of two systems into audio signals of a plurality of second channels mutually correlated by a predetermined matrix operation. And the second plurality of audio signals for each channel.
Separating means for separating the upper and lower bits data,
The higher-order bit data separated by the separating means is obtained for each channel, in response to input data, to obtain a leading sample value and to perform a plurality of linear prediction methods having different characteristics.
A linear prediction of the signal from past to present in the more time domain
Respectively, and the predicted linear prediction value and the voice signal are predicted.
And a prediction encoding means for selecting a linear prediction method such that the prediction residual obtained from the signal is the minimum, and a head sample value, a prediction residual, and a linear prediction method for each channel selected by the prediction encoding means. A speech encoding apparatus comprising: a prediction coded data including the coded data; and means for multiplexing the lower bit data and the separation flag separated by the separation means in a predetermined format. 2) correlating means for converting digital audio signals of a first plurality of channels having the same sampling frequency and composed of two systems into audio signals of a plurality of mutually correlated channels by a predetermined matrix operation; The converted second plurality of channels of the audio signal, the head sample value is obtained in response to the audio signal input for each channel, and the current signal from the past in the time domain by a plurality of linear prediction methods having different characteristics . Each linear prediction is predicted,
Obtained from the predicted linear prediction value and the audio signal
That the predictive coding means for predictive residual is predictive coding by selecting a linear prediction method that minimizes the leading sample value and the prediction residual and linear prediction method for each channel selected by said predictive coding means Means for multiplexing predictive encoded data including a predetermined format in a predetermined format.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G10L 9/14 J 9/18 D

Claims (2)

[Claims] [Claim 1] The same sampling frequency and 2
Digital audio signals of a first plurality of channels composed of two systems are correlated with each other by a predetermined matrix operation.
Correlating means for converting the audio signals of the second plurality of channels into audio signals of two or more channels; separating means for separating the audio signals of the second plurality of channels into upper bit and lower bit data as necessary for each channel; In this case, the upper bit data is obtained for each channel in response to the input data, to obtain a first sample value, and to calculate a prediction residual among a plurality of prediction values of a current signal from a past signal in a time domain. Predictive encoding means for selecting a linear prediction method that minimizes the difference; predictive data including a head sample value of each channel selected by the predictive encoding means, a prediction residual, and a linear prediction method; Means for multiplexing the lower-order bit data and the separation flag in a predetermined format when separated by the above-mentioned method. 2. The same sampling frequency and 2
Digital audio signals of a first plurality of channels composed of two systems are correlated with each other by a predetermined matrix operation.
Correlation means for converting into a plurality of two-channel audio signals, the converted second plurality of channels of audio signals, in response to the audio signal input for each channel to obtain a leading sample value, and in the time domain Prediction encoding means for selecting and predictively encoding a linear prediction method whose prediction residual is minimized among a plurality of prediction values of the current signal from the past signal, and each of the prediction encoding means selected by the prediction encoding means Means for multiplexing, in a predetermined format, predicted data including a head sample value of a channel, a prediction residual, and a linear prediction method.