JP3387091B2 - Optical recording medium, audio transmission method and audio decoding method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical recording medium of data obtained by predictively encoding a voice signal, a voice transmission method and a voice decoding method.

[0002]

2. Description of the Related Art As a method of predictively encoding a voice signal,
The inventor of the present application (Japanese Patent Application No. 9-289159) uses a plurality of predictors having different characteristics for the original digital audio signal of one channel to convert the past signal from the past signal in the time domain to the present signal. A method is proposed in which a plurality of linear prediction values are calculated, a prediction residual for each predictor is calculated from the original digital audio signal and the plurality of linear prediction values, and the minimum value of the prediction residuals is selected.

[0003]

However, in the above method, the original digital audio signal has a sampling frequency = 96.
A compression effect can be obtained to some extent when the frequency is about 20 kHz and the number of quantization bits is about 20 bits. However, in recent years, the DVD audio disc uses a sampling frequency (= 192 kHz) that is twice as high as this, and the number of quantization bits is also increased. Also, since 24 bits tend to be used, it is necessary to improve the compression rate.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide an optical recording medium having data recorded therein, which can improve the compression rate when predictively encoding a voice signal, a voice transmission method and a voice decoding method.

[0005]

In order to achieve the above object, the present invention comprises the following 1) to 3) means. That is,

1) At least left, center, right,
A step of converting digital audio signals of a first plurality of channels including surround left and surround right 5 channels into a second plurality of channels of audio signals having the same sampling frequency and having a correlation by a predetermined matrix operation. A second multiple channel audio signal for each channel, in response to the input audio signal, to obtain a leading sample value in a frame unit of a predetermined time, and the current predicted from past signals in the time domain. Of the multiple prediction values of the signal of, the linear prediction method of which the prediction residual is the minimum value is the linear prediction value of the signal from the past in the time domain is predicted by multiple linear prediction methods with different characteristics, respectively. wherein the linear prediction method as the prediction residuals obtained from the expected linear prediction value and the audio signal and is the smallest frame
The sub-frame is further divided into sub-frame units for predictive coding, and predictive-coded data including the selected leading sample value, prediction residual and linear prediction method is packed.
In case of King, the prediction residual is based on bit information.
The predictive coding data is packed together with the number of bits.
Packet header and compressed PCM private header
Packetized with the audio compression PCM data section
In the audio compression PCM data section in the user data
A speech decoding method for decoding an original speech signal from data coded by a speech coding method, which comprises a packing step , wherein a leading sample value of each selected channel, a prediction residual and a linear prediction method. A speech decoding method comprising: a step of calculating a predicted value from predictive coded data including the following; and a step of restoring the digital audio signals of the first plurality of channels from the calculated predicted value. 2) Digital audio signals of a first plurality of channels including at least 5 channels of left, center, right, surround left and surround right are correlated to each other by a predetermined matrix operation and having the same sampling frequency. Converting the audio signals of the second plurality of channels into audio signals of a plurality of channels;
A linear prediction method that minimizes the prediction residual among multiple predicted values of the current signal that is obtained from past signals in the time domain while obtaining it in frame units for a predetermined time. A linear prediction method of predicting a linear prediction value of a current signal from the past in the time domain by the method, and a prediction residual obtained from the predicted linear prediction value and the speech signal is minimized by the frame prediction method. Further division
A step of selecting and performing predictive coding for each subframe, and a case of packing predictive coded data including the selected leading sample value, prediction residual, and linear prediction method.
The prediction residual with the number of bits based on the bit information.
And the predicted coded data
Header and compressed PCM private header and audio
User data packetized with the compressed PCM data part
In the audio compression PCM data part in
That a step and, audio signal transmission method for transmitting an audio signal encoded by the speech encoding method comprising, predictive coded data including said selected first sample value and the prediction residual and the linear prediction method A method for transmitting an audio signal, which comprises packetizing and transmitting the data via a communication line. 3) Digital audio signals of a first plurality of channels including at least 5 channels of left, center, right, surround left and surround right are subjected to a predetermined matrix operation and have the same sampling frequency, and are correlated to each other. Converting into a plurality of channels of audio signals, the second plurality of channels of audio signals are obtained for each channel in response to an input audio signal, and a leading sample value is obtained in frame units of a predetermined time, and characteristics are A linear prediction that predicts a linear prediction value of a current signal from the past in the time domain by a plurality of different linear prediction methods and minimizes a prediction residual obtained from the predicted linear prediction value and the speech signal. Selecting a method in units of subframes obtained by further dividing the frame, and performing predictive coding; A prediction coded data including a sample value, a prediction residual and a linear prediction method is multiplexed in a predetermined format, and the prediction residual is packed based on bit number information according to the prediction residual. , When packing the prediction coded data including the selected leading sample value, the prediction residual, the linear prediction method, and the bit number flag of the prediction residual, the prediction residual is converted into bits.
With packing the number of bits based on the information, the
The predictive coded data contains packet header and compressed PCM
The header and audio compression PCM data section
The audio compression P in the packetized user data
The predictive coded data is recorded as packed in a CM data part, and the predictive coded data is recorded as data for calculating a predictive value used to restore the digital audio signals of the first plurality of channels. An optical recording medium characterized by being provided.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. 1 is a block diagram showing a first embodiment of a speech coding apparatus and a speech decoding apparatus corresponding thereto applied to the present invention, FIG. 2 is a block diagram showing a coding unit of FIG. 1 in detail, and FIG. 1 is a block diagram showing in detail the decoding unit of FIG. 1, FIG. 4 is an explanatory diagram showing a format of a DVD pack, FIG. 5 is an explanatory diagram showing a format of an audio pack of a DVD, and FIGS. 6 and 7 are flowcharts showing an audio transmission method. Is.

The following four systems are known as the multi-channel system. (1) Dolby Surround system front L, C, R 3 channels + rear S 1 channel 4 channels in total (2) Dolby AC-3 system front L, C, R, SW 4 channels + rear SL, SR 2 channels in total 6 channels (3) DTS (Digital Theater System) system 6 channels (L, C,
(R, SW, SL, SR) (4) SDDS (Sony Dynamic Digital Sound) system 6 channels of front L, LC, C, RC, R, SW + 2 channels of rear SL, SR, total 8 channels

The 5-channel (ch) correlation circuit 1 on the encoding side shown in FIG. 1 is a left (L), center (C), right (R), surround left (SL), and surround right as an example of a multi-channel signal. (SR) 5ch PC
For M data, the next 5 ch (L), (D
1) to (D4) and shown in detail in FIG.
Output to. L = L (reference channel) D1 = C− (L + R) / 2 D2 = R−L D3 = SL−a × L D4 = SR−b × R where 0 ≦ a, b ≦ 1

The encoding section 2 is provided for each channel as shown in detail in FIG.
The PCM data of (L) and (D1) to (D4) is predictively encoded, and this is transmitted to the decoding side via a recording medium or a communication medium. On the decoding side, the decoding unit 3 shown in detail in FIG.
The prediction coded data of ch (L), (D1) to (D4) are decoded, and then the original 5 ch is restored by the 5-channel correlation circuit 4 as follows. R = (R-L) + L C = C- (L + R) / 2 + L / 2 + R / 2 SL = SL-a * L + a * L SR = SR-b * R + b * R

The encoding unit 2 will be described in detail with reference to FIG. The PCM data of each ch (L), (D1) to (D4) is stored in the one frame buffer 10 for each frame. Then, the sample data of each ch of one frame is applied to the prediction circuits 15L and 15D1 to 15D4, respectively, and the leading sample data of one frame of each ch is applied to the formatting circuit 19. Prediction circuit 15
L, 15D1 to 15D4 are each ch (L), (D
For the PCM data of 1) to (D4), a plurality of predictors (not shown) having different characteristics are used to calculate a plurality of linear prediction values of the current signal from past signals in the time domain, and the original P
A prediction residual for each predictor is calculated from the CM data and the plurality of linear prediction values. Subsequent buffer / selector 16L, 16D
1 to 16D4 are prediction circuits 15L and 15D1 to 15D1, respectively.
Temporarily store each prediction residual calculated by 15D4,
The minimum value of the prediction residual is selected for each subframe designated by the selection signal generator 17.

The selection signal generator 17 packs the bit number flag of the prediction residual into a packing circuit 18 and a formatting circuit 19.
, And a predictor selection flag indicating a predictor with the smallest prediction residual to the formatting circuit 19. The packing circuit 18 is the buffer / selector 16
The prediction error for 5 channels selected by L and 16D1 to 16D4 is packed with the specified number of bits based on the bit number flag specified by the selection signal generator 17.

The following formatting circuit 19 is for one frame: a frame header, each channel (L), the head sample value of one frame of (D1) to (D4), each channel (L), Predictor selection flag for each subframe of (D1) to (D4), each channel (L), bit number flag for each subframe of (D1) to (D4), each channel (L), ( The prediction residual data string (variable number of bits) of D1) to (D4) is multiplexed and output as a variable rate bit stream. According to such predictive coding, the original signal is, for example, sampling frequency = 96 kHz,
Number of quantization bits = 24 bits, 71 for 5 channels
A compression rate of% can be realized.

Next, the decoding unit 3 will be described with reference to FIG. The variable rate bit stream data in the above format is separated by the deformatting circuit 21 based on the frame header. And each channel (L),
The head sample data of one frame of (D1) to (D4) and the predictor selection flag are prediction circuits 23L and 23D, respectively.
1 to 23D4, each channel (L), (D1) to
The bit number flag (D4) and the prediction residual data string are applied to the unpacking circuit 22. Here, the prediction circuit 23
A plurality of predictors (not shown) in L and 23D1 to 23D4 are prediction circuits 15L and 15D1 to 15D on the encoding side, respectively.
The characteristics are the same as those of the plurality of predictors in D4, and those having the same characteristics are selected by the predictor selection flag.

The unpacking circuit 22 is for each channel (L),
The prediction residual data strings (D1) to (D4) are separated on the basis of each bit number flag, and the prediction circuits 23L and 23 are respectively separated.
Output to D1 to D4. Prediction circuits 23L and 23D1
23D4, the current prediction residual data of each channel (L), (D1) to (D4) from the unpacking circuit 22 and a plurality of internal predictors are selected by the predictor selection flag. The previous predicted value predicted by each one is added to calculate the current predicted value, and then the PCM of each sample value is based on the leading sample value of one frame.
Data is calculated.

Here, when the variable rate bit stream data predictively coded by the coding unit 2 shown in FIG. 2 is recorded on a DVD audio disc as an example of a recording medium, the audio of the compressed PCM shown in FIG. 4 is used. (A)
Packed in a pack. This pack includes 4 bytes of pack start information and 6 bytes of SCR for 2034 bytes of user data (A packet, V packet).
(System Clock Reference: System clock reference value)
Information, 3 bytes of Mux rate information, and 1 byte of stuffing, a total of 14 bytes of pack header are added (1 pack = 2048 bytes in total). In this case, the SCR information, which is the time stamp,
The time of pack A in the same title can be managed by setting "1" in the first pack in the ACB unit and making it consecutive in the same title.

As shown in detail in FIG. 5, the compressed PCM A packet includes a packet header of 17, 9 or 14 bytes, a compressed PCM private header, and audio compressed PCM data of 1 to 2011 bytes in the format shown in FIG. It is composed by. The private header of the compressed PCM includes: 1-byte substream ID, 2-byte UPC / EAN-ISRC (Universal Pr
oduct Code / European Article Number-International S
tandard Recording Code) number and UPC / EAN-
ISRC data, 1-byte private header length, 2-byte first access unit pointer, 8-byte audio data information (ADI), and 0-7 bytes of stuffing bytes. There is.

When the variable rate bit stream data predictively coded by the coding unit 2 shown in FIG. 2 is transmitted through the network, the coding side packetizes it for transmission as shown in FIG. (Step S41),
Next, a packet header is added (step S42), and then this packet is sent out on the network (step S43). The decoding side removes the header as shown in FIG. 7 (step S51), restores the data (step S52), stores the data in the memory, and waits for the decoding (step S53).

Next, a second embodiment will be described with reference to FIGS. In the above-described embodiment, the signals (L) and (D1) to (D4) having one type of correlation are configured to be predictively coded, but in the second embodiment, a plurality of types of correlation (L), It is configured to selectively predictively code one type of signal. Therefore, in the encoding unit shown in FIG. 8, first to nth correlation circuits 1-1 to 1-n are provided,
The n correlation circuits 1-1 to 1-n are, for example, 5 ch (L,
C, R, SL, SR) PCM data is converted into n types of 5ch signals having different correlations. The nth correlation circuit 1-n performs conversion as follows, for example. L = L (reference channel) D1 = C-L D2 = R-L D3 = SL-L D4 = SR-R

The prediction circuits 15L and 15D1 to 15D4 and the buffer / selector 16 are provided for each of the correlation circuits 1-1 to 1-n.
L, 16D1 to 16D4 are provided, and the group having the highest compression rate is selected by the correlation selection signal generator 17b based on the data amount of the minimum value of the prediction error for each group.
At this time, the selection flag (correlation circuit selection flag, correlation coefficients a and b of the correlation circuit) is added and multiplexed.

On the decoding side shown in FIG. 9, there are n correlation circuits 4-for the correlation circuits 1-1 to 1-n on the encoding side.
1 to 4-n (or one correlation circuit 4 whose coefficients a and b can be changed) are provided. When the n groups of prediction circuits shown in FIG. 8 have the same configuration, the decoding device need not be provided with n groups of prediction circuits as shown in FIG.
A prediction circuit for one group is sufficient. Then, based on the selection flag transmitted from the encoding device, the correlation circuit 4-1
~ 4-n is selected, or the coefficients a and b are set to restore the original 5ch (L, C, R, SL, SR).

In the first embodiment, the signals L, D1 to D4 having one type of correlation are configured to be predictively coded, but the groups of the signals L and D1 to D4 and the original signals are used. The groups of the signals L, C, R, SL and SR may be predictively coded and the group having the higher compression rate may be selected.

[0023]

As described above, according to the present invention, the voice signals of a plurality of channels are converted into the voice signals of the second plurality of channels having the correlation and are predictively coded. The compression ratio can be improved in the case of predictive coding.

[Brief description of drawings]

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

FIG. 2 is a block diagram showing in detail a coding unit of FIG.

FIG. 3 is a block diagram showing the decoding unit of FIG. 1 in detail.

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

FIG. 5 is an explanatory diagram showing a format of a DVD audio pack.

FIG. 6 is a flowchart showing a voice transmission method.

FIG. 7 is a flowchart showing a voice transmission method.

FIG. 8 is a block diagram showing another audio encoding device.

FIG. 9 is a block diagram showing a speech decoding apparatus corresponding to FIG.

[Explanation of symbols]

1, 1-1 to 1-n, 4, 4-1 to 4-n Correlation circuit (correlation means) 15L, 15D1 to 15D4 Prediction circuit (buffer / selectors 16L, 16D1 to 16D4 and prediction coding means) .) 16L, 16D1 to 16D4 Buffer / Selector

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁷ identification code FI H04B 14/04 G10L 9/18 D H04S 3/00 M (56) Reference JP-A 64-44499 (JP, A) JP 3-108824 (JP, A) JP 8-65169 (JP, A) JP 10-233058 (JP, A) JP 10-320928 (JP, A) (58) Fields investigated (Int .Cl. ⁷ , DB name) G10L 19/00

Claims (3)

(57) [Claims] 1. Digital audio signals of a first plurality of channels including at least 5 channels of left, center, right, surround left and surround right are correlated by having a same sampling frequency by a predetermined matrix operation. A step of converting the audio signal of the second plurality of channels, for each channel of the audio signal of the second plurality of channels, in response to the input audio signal, the first sample value at a predetermined time
A plurality of linear prediction methods with different characteristics, which are obtained in units of frames between frames, and which have the smallest prediction residual among the predicted values of the current signal predicted from the past signal in the time domain According to the above, the linear prediction value of the current signal is predicted from the past in the time domain, and a linear prediction method that minimizes the prediction residual obtained from the predicted linear prediction value and the speech signal is further added to the frame. Divided service
Selecting in units of subframes and performing predictive coding, and packing the predictive coded data including the selected leading sample value, prediction residual, and linear prediction method ,
Packing the prediction residual with the number of bits based on the bit information.
And the predicted coded data is transferred to the packet header and compressed PCM.
Private header and audio compression PCM data section
Audio pressure in user data packetized by
A voice decoding method for decoding an original voice signal from data encoded by a voice encoding method, which comprises a step of packing in a reduced PCM data part , wherein a leading sample value and a prediction residual of each selected channel are included. A speech decoding method comprising: a step of calculating a prediction value from predictive coded data including a difference and a linear prediction method; and a step of restoring the digital audio signals of the first plurality of channels from the calculated prediction value. 2. Digital audio signals of a first plurality of channels including at least 5 channels of left, center, right, surround left and surround right are correlated by having a same sampling frequency by a predetermined matrix operation. A step of converting the audio signal of the second plurality of channels, for each channel of the audio signal of the second plurality of channels, in response to the input audio signal, the first sample value at a predetermined time
A plurality of linear prediction methods with different characteristics, which are obtained in units of frames between frames, and which have the smallest prediction residual among the predicted values of the current signal predicted from the past signal in the time domain According to the above, the linear prediction value of the current signal is predicted from the past in the time domain, and a linear prediction method that minimizes the prediction residual obtained from the predicted linear prediction value and the speech signal is further added to the frame. Divided service
Selecting in units of subframes and performing predictive coding, and packing the predictive coded data including the selected leading sample value, prediction residual, and linear prediction method ,
Packing the prediction residual with the number of bits based on the bit information.
And the predicted coded data is transferred to the packet header and compressed PCM.
Private header and audio compression PCM data section
Audio pressure in user data packetized by
A voice signal transmission method for transmitting a voice signal encoded by a voice encoding method, comprising the step of packing in a reduced PCM data part , wherein the selected leading sample value, prediction residual, and linear prediction method. A method of transmitting a voice signal, characterized in that the predictive coded data including the above is packetized and transmitted via a communication line. 3. Digital audio signals of a first plurality of channels including at least 5 channels of left, center, right, surround left and surround right are mutually correlated by having a same sampling frequency by a predetermined matrix operation. Converting into a second plurality of channels of audio signals, for each channel of the second plurality of channels of audio signals, in response to the input audio signal, to obtain a leading sample value in frame units of a predetermined time , The linear prediction values of the current signal are predicted from the past in the time domain by a plurality of linear prediction methods having different characteristics, and the prediction residual obtained from the predicted linear prediction value and the speech signal is minimized. A linear prediction method in units of subframes obtained by further dividing the frame to perform predictive coding, and The prediction coded data including the leading sample value, the prediction residual, and the linear prediction method are multiplexed in a predetermined format, and the prediction residual is packed based on the bit number information according to the prediction residual. When packing the prediction coded data including the selected leading sample value, the prediction residual, the linear prediction method, and the bit number flag of the prediction residual by the step, the prediction residual is based on the bit information.
The predicted coded data is packed in a packet header and a compressed PCM.
Private header and audio compression PCM data section
Audio pressure in user data packetized by
The predictive coded data is packed and recorded in a reduced PCM data part, and the predictive coded data is data for calculating a predictive value used to restore the digital audio signals of the first plurality of channels. An optical recording medium characterized by being recorded.