JPH1127240A - Device and method for digital signal encoding, device and method for decoding, recording medium and transmission method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a plurality of reproduction signals of a reproductive quality in accordance with a plurality of code-decoding state by using the same decoding data. SOLUTION: An input digital signal from an input terminal 200 is divided by quadrature mirror filters(QMF) 201 and 202 and block size decision circuits 206 to 208 into small blocks, which are segmented with regard to time and frequency, and converted to spectrum data on a frequency axis by modified discrete cosine transformer circuits 203 to 205. Decoding is performed by appropriate bit assignment decoding circuit 210 to 212 in accordance with the number of bits assigned by a bit distribution computation circuit 209. Ciphering circuits 219 to 221 as ciphering means executes ciphering to the segmented small blocks. A code key control circuit 222 generates a code key for controlling ciphering by ciphering circuits 219 to 221.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to recording and reproducing compressed and encrypted data obtained by bit-compressing and encrypting a digital audio signal and the like, a recording medium on which the compressed and encrypted data is recorded, and a method for storing the compressed and encrypted data. Regarding transmission systems,
Digital signals can be compressed and recorded or recorded by subdividing time and frequency, encrypting each compressed small block independently, and reproducing multiple decryption and decompression states with the same compressed and encrypted information. Digital signal processing device for transmission and / or reproduction or reception and expansion
Alternatively, the present invention relates to an information compression method and a recording medium.

[0002]

2. Description of the Related Art The present applicant has previously described, for example, Japanese Patent Application No. Hei.
No. 221364, Japanese Patent Application No. 2-221365, Japanese Patent Application No. 2
In each specification, drawings and the like of Japanese Patent Application No. 228821 and Japanese Patent Application No. 2-282323, a technique is proposed in which an input digital audio signal is bit-compressed and a predetermined data amount is recorded as a recording unit in a burst. ing.

This technique uses a magneto-optical disk as a recording medium, and records and reproduces AD (adaptive difference) PCM audio data defined in a so-called CD-I (CD-interactive) or CD-ROM XA audio data format. The ADPCM data is recorded in a burst on the magneto-optical disk using, for example, 32 sectors of ADPCM data and several sectors for linking for interleave processing as a recording unit.

Several modes can be selected for ADPCM audio in a recording / reproducing apparatus using this magneto-optical disk. Is 37.
"Level A" of 8 kHz, "Level B" of 47.8% compression rate and sampling frequency of 37.8 kHz, "Level C" of 8 times compression rate and sampling frequency of 18.9 kHz
Is stipulated. That is, for example, the “level B”
In the case of, the digital audio data is approximately 1/4
The playback time (play time) of a disc recorded in this "level B" mode is four times that of a standard CD format (CD-DA format). Since a recording and reproducing time of the same order as a standard 12 cm can be obtained with a smaller disk, the size of the apparatus can be reduced.

However, the rotation speed of the disk is a standard C
Since it is the same as D, for example, in the case of the above “Level B”,
As a result, compressed data for a reproduction time four times as long as the predetermined time is obtained. For this reason, for example, the same compressed data is read out four times in units of time such as sectors or clusters, and only one of the compressed data is used for audio reproduction. Specifically, when scanning (tracking) a spiral recording track, a track jump is performed such that the track returns to the original track position for each rotation, and the same track is repeatedly tracked four times. The playback operation will proceed. This means that normal compressed data only needs to be obtained at least once out of, for example, four overlapping readings, which is resistant to errors due to disturbances and the like, and is particularly preferable when applied to portable small devices.

Further, the present applicant has disclosed a bit allocation method for realizing efficient and good compression by applying Japanese Patent Application No. Hei.
No. 952 in the specification and drawings. In this technique, when allocating bits, normalization is performed by a representative value in each small block such as a so-called critical band (critical band), that is, so-called block floating is performed. The weighting is performed according to the band corresponding to the small block. According to this technique, when there is no extreme variation in the magnitude of the spectrum in each small block, it is possible to perform compression satisfactorily.

On the other hand, for the procedure of encrypting or authenticating communication or distribution contents to a specific person, for example, Data E
ncryption Standard, Federal Information Processing
Standards Publication 46, National Bureau of Stan
dards, US Department of Commerce (1977), and the so-called DES and Miyaguchi, S., Kurihara,
S., Ohta, K. and Morita, H .: Expansion of FEALCiph
er, NTT Review, Vol. 2, No. 6, pp. 117-127 (1990) have been proposed and are being put to practical use. These are generally called symmetric key cryptosystems,
A sender who wants to send a certain plaintext encrypts it with an encryption key shared with the receiver, and sends the ciphertext to a communication path. This cipher text can be decrypted only by the recipient sharing the encryption key, and confidentiality is guaranteed.

[0008]

However, in the case where digital audio data is compressed by applying the above-mentioned technology, and the digital audio data is encrypted and distributed to a receiver via a recording medium or a communication path, a plurality of receivers are required. Considering the case where a large amount of information is distributed simultaneously to the receiver and the receiver selectively performs decryption, or the case where the sender selectively permits decryption for each receiver, In order to be selectable, it is necessary to attach information such as an unencrypted table of contents or sample. At this time, if information is selected and encrypted for each recipient and distributed, the above-mentioned attachment of unencrypted information becomes unnecessary, but as the number of recipients increases, the distribution It requires a lot of work.

Further, even in a case where different information such as a quality, for example, a reproduction band in audio data, is distributed to each receiver, it is necessary to encrypt each quality and distribute it to each receiver. Alternatively, when all pieces of information encrypted for each quality are distributed together, it is not necessary to selectively transmit the information to each receiver, but information unnecessary to the receiver is transmitted, and information to be distributed is transmitted. Since the volume increases, the distribution efficiency decreases. In particular, when distributing information via a communication channel, this can be a major obstacle.

[0010] The present invention has been made in view of such circumstances, and employs a digital audio data compression technique capable of selecting the entire or partial range of encryption, and is not encrypted. Digital signal encoding that enables selective decoding without attaching information, enables efficient distribution of information of different qualities, and can handle multiple encryptions with the same decoding device It is an object of the present invention to provide an apparatus and method, a decoding apparatus and method, a recording medium, and a transmission method.

[0011]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a block distribution means for distributing an input digital signal into small blocks subdivided in at least one of time and frequency; Spectrum data output means for obtaining spectrum data, bit allocation calculation means for calculating the number of allocated bits for compression for each of the subdivided small blocks, and encoding according to the number of bits allocated by the bit allocation calculation means Assigned bit encoding means for performing encryption, encryption means for encrypting at least a part of the subdivided small blocks, and encryption for generating an encryption key for controlling encryption by the encryption means. Key control means.

Here, the encryption means can select an encryption range, and the encryption key control means selectively controls the encryption range in the encryption means.

Further, the input digital signal is distributed and compressed into small blocks subdivided with respect to time and frequency, and is independently and / or individually or multiplexed and encrypted for each small block subdivided with respect to time and frequency. Reproducing a plurality of encryption / decryption / decompression states using the same compression / encryption information.

That is, the small block is obtained by subdividing the input digital signal with respect to time and frequency, and the spectrum data output means includes orthogonal transform means for obtaining spectrum data on a frequency axis for each of the small blocks. To have. Further, the bit allocation means obtains an allowable noise spectrum from the spectrum data, distributes the obtained allowable noise spectrum into small blocks subdivided in time and frequency, and performs bit allocation for compression. Is mentioned.

Further, the encrypting means independently encrypts at least one of time and frequency for each of the subdivided small blocks, and the encrypting key control means comprises:
An encryption key for independently encrypting each of the subdivided small blocks is generated. Alternatively, the encrypting means comprises serially connected means for encrypting multiple small blocks subdivided with respect to time, and the encryption key control means converts the subdivided small blocks into One is to generate an encryption key for multiple encryption.

Further, the block distribution means changes the time length of the processing block for information compression in accordance with the input signal, and changes the input signal of the processing block and the input signal of the other processing block. It may include a processing block length determining means for determining the time length of the processing block based on the change and / or power, energy, or peak information.

A signal recording medium according to the present invention is a medium on which a digital signal encoded as described above is recorded.

Further, the digital signal transmission method according to the present invention includes a step of transmitting the digital signal encoded as described above.

The coded data coded as described above and supplied via a recording medium or a transmission path can obtain a plurality of reproduction qualities corresponding to a plurality of encryption / decryption states with the same coded data. Can be.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of a digital signal encoding apparatus and method, a decoding apparatus and method, a recording medium, and a transmission method according to the present invention will be described below with reference to the drawings.

FIG. 1 is a block circuit diagram showing a schematic configuration of a digital signal encoding apparatus according to an embodiment of the present invention. The digital signal encoding apparatus shown in FIG.
This is also an apparatus to which the digital signal encoding method according to the embodiment of the present invention is applied.

The digital signal encoding apparatus according to the embodiment of the present invention shown in FIG. 1 performs high-efficiency compression encoding using an encryption technique. That is, an input digital signal such as an audio PCM signal is encoded with high efficiency using techniques such as band division coding (SBC), adaptive conversion coding (ATC), adaptive bit allocation, and encryption using an encryption key. ing.

In FIG. 1, an input terminal 200 has
For example, a digital signal such as an audio PCM signal is input, and as a block distribution means for distributing the input digital signal into small blocks subdivided in time and frequency, for example, a QMF (Quadrature Mirrer Filt
er) 201, 202 and block size determination circuit 20
6, 207 and 208 are provided. Further, the input digital signal is an orthogonal transform circuit as a spectrum data output means for obtaining spectrum data on a frequency axis, for example, an MDCT (Modified Discrete Cosine Transform)
Sent to the circuits 203, 204, and 205,
CT processing is performed. The bit allocation calculation circuit 209 obtains the number of allocated bits for compression for each of the subdivided small blocks, and calculates the adaptive bit allocation encoding circuits 210, 211, 21.
2, encoding is performed according to the number of bits allocated by the bit allocation calculation circuit 209. The encryption circuits 219 to 221 and 223 to 225 as encryption means respectively perform encryption on the subdivided small blocks.
The encryption key control circuit 222 includes encryption circuits 219 to 221,
An encryption key for controlling encryption by 223 to 225 is generated. In this case, the encryption key control circuit 222 selects whether to perform all or only a part of the encryption in the encryption circuits 219 to 221 and 223 to 225, and uses a common encryption key or different encryption keys. Control or
Control or the like for changing the encryption state over time is performed.

Here, prior to the detailed description of the digital signal encoding apparatus according to the embodiment of the present invention shown in FIG. Alternatively, a reproducing device will be described with reference to FIG.

FIG. 2 shows an outline of a magneto-optical disk recording / reproducing apparatus as a specific example of a compressed data recording and / or reproducing apparatus using a digital signal encoding apparatus and a decoding apparatus according to an embodiment of the present invention. 1 shows the configuration.

In the magneto-optical disk recording / reproducing apparatus shown in FIG. 2, a magneto-optical disk 1 driven by a spindle motor 51 is used as a recording medium. When recording data on the magneto-optical disk 1, for example, a so-called magnetic field modulation recording is performed by applying a modulation magnetic field corresponding to the recording data with the magnetic head 54 while irradiating the laser light with the optical head 53, Data is recorded along one recording track. At the time of reproduction, the recording track of the magneto-optical disk 1 is traced by a laser beam by the optical head 53, and reproduction is performed magneto-optically.

The optical head 53 includes, for example, a laser light source such as a laser diode, a collimator lens, an objective lens,
It is composed of optical components such as a polarizing beam splitter and a cylindrical lens, and a photodetector having a light receiving section having a predetermined pattern. The optical head 53 is provided at a position facing the magnetic head 54 via the magneto-optical disk 1. When data is recorded on the magneto-optical disk 1, the magnetic head 54 is driven by a recording-system head drive circuit 66, which will be described later, to apply a modulation magnetic field in accordance with the recorded data. By irradiating the track with laser light, thermomagnetic recording is performed by a magnetic field modulation method. The optical head 53 detects reflected light of the laser beam applied to the target track, detects a focus error by, for example, a so-called astigmatism method, and detects a tracking error by, for example, a so-called push-pull method. When reproducing data from the magneto-optical disk 1, the optical head 53 detects the focus error and the tracking error, and at the same time, detects the difference in the polarization angle (Kerr rotation angle) of the reflected light of the laser light from the target track to reproduce the data. Generate a signal.

The output of the optical head 53 is supplied to an RF circuit 55. The RF circuit 55 extracts the focus error signal and the tracking error signal from the output of the optical head 53 and supplies the focus error signal and the tracking error signal to the servo control circuit 56.
Feed to 1.

The servo control circuit 56 comprises, for example, a focus servo control circuit, a tracking servo control circuit, a spindle motor servo control circuit, a thread servo control circuit and the like. The focus servo control circuit performs focus control of the optical system of the optical head 53 so that the focus error signal becomes zero. Further, the tracking servo control circuit performs tracking control of the optical system of the optical head 53 so that the tracking error signal becomes zero. Further, the spindle motor servo control circuit controls the spindle motor 51 so as to rotate the magneto-optical disk 1 at a predetermined rotation speed (for example, a constant linear speed). The thread servo control circuit moves the optical head 53 and the magnetic head 54 to target track positions of the magneto-optical disk 1 specified by the system controller 57. The servo control circuit 56 that performs such various control operations sends information indicating the operation state of each unit controlled by the servo control circuit 56 to the system controller 57.

A key input operation unit 58 and a display unit 59 are connected to the system controller 57. The system controller 57 controls a recording system and a reproduction system in an operation mode specified by operation input information from the key input operation unit 58. The system controller 57 also controls the optical head 53 and the magnetic head 5 based on the address information in sector units reproduced from the recording track of the magneto-optical disk 1 by the header time, the subcode Q data, and the like.
4 manages a recording position and a reproduction position on the recording track which are being traced. Further, the system controller 57
Controls the display unit 59 to display the reproduction time based on the data compression ratio and the reproduction position information on the recording track.

This reproduction time display is based on the reciprocal of the data compression ratio (absolute time information) with respect to the sector-based address information (absolute time information) reproduced from the recording track of the magneto-optical disk 1 by the so-called header time or the so-called subcode Q data. For example, in the case of 1/4 compression, the actual time information is obtained by multiplying by 4), and this is displayed on the display unit 9. At the time of recording, if absolute time information is recorded in advance on a recording track of a magneto-optical disk or the like (preformatted), the preformatted absolute time information is read and the data compression ratio is adjusted. By multiplying the reciprocal, the current position can be displayed by the actual recording time.

In addition, the system controller 57
For encryption and decryption (partialization) in the TC (Adaptive Transform Coding) PCM encoder 63 or the ATC decoder 73, an encryption key specified by operation input information from the key input operation unit 58 is supplied.

Next, in the recording system of the magneto-optical disk recording / reproducing apparatus shown in FIG. 2, an analog audio input signal Ain from an input terminal 60 is supplied to an A / D converter 62 via a low-pass filter 61. The / D converter 62 quantizes the analog audio input signal Ain. A
The digital audio signal obtained from the / D converter 62 is supplied to the ATC encoder 63. The digital audio input signal Din from the input terminal 67 is supplied to the ATC encoder 63 via the digital input interface circuit 68. The ATC encoder 63 is
Bit compression (data compression) processing is performed on the digital audio PCM data at a predetermined transfer rate obtained by quantizing the analog audio input signal Ain by the A / D converter 62. At this time, information necessary for controlling the encryption key is transmitted from the system controller 57 to the ATC encoder 63.
Supplied to Here, the compression ratio is described as four times, but the present embodiment is configured not to depend on this magnification, and can be arbitrarily selected according to an application example.

Next, writing and reading of data in the memory 64 are controlled by the system controller 57.
The ATC data supplied from the ATC encoder 63 is temporarily stored, and is used as a buffer memory for recording on a disk as needed. That is, for example, the compressed audio data supplied from the ATC encoder 63 has a standard C
Data transfer rate of D-DA format (75 sectors /
Second), that is, 18.75 sectors / second, and the compressed data is continuously written to the memory 14. As described above, it is sufficient for the compressed data (ATC data) to record one sector for every four sectors. However, such recording every four sectors is practically impossible. I try to keep a record. This recording is performed at intervals of the same data transfer rate (75 sectors / second) as a standard CD-DA format by using a cluster consisting of a plurality of predetermined sectors (for example, 32 sectors + several sectors) as a recording unit through a pause period. It is done on a regular basis. That is, in the memory 14, ATC audio data continuously written at a low transfer rate of 18.75 (= 75/4) sectors / second according to the bit compression rate is used as recording data. It is read out in bursts at the transfer speed. The overall data transfer rate of the read and recorded data, including the recording pause period, is as low as 18.75 sectors / sec, but within the time of the recording operation performed in bursts. The instantaneous data transfer rate in the above is the standard 75 sectors / second. Therefore, when the disk rotation speed is the same speed (constant linear speed) as the standard CD-DA format, the same recording density and storage pattern as those of the CD-DA format are recorded.

ATC audio data, ie, recorded data, read from the memory 64 in a burst at the (instantaneous) transfer rate of 75 sectors / second is transferred to the encoder 65.
Supplied to Here, from the memory 64 to the encoder 65
In the data sequence supplied to the cluster, the unit continuously recorded in one recording is a cluster including a plurality of sectors (for example, 32 sectors) and several sectors for cluster connection arranged before and after the cluster. The cluster connection sector is set to be longer than the interleave length in the encoder 65, so that even if interleaved, data in other clusters is not affected.

The encoder 65 performs the recording data supplied from the memory 64 in a burst manner as described above.
Encoding processing (parity addition and interleaving processing) for error correction, EFM encoding processing, and the like are performed. The recording data that has been subjected to the encoding process by the encoder 65 is supplied to the magnetic head drive circuit 66. The magnetic head drive circuit 66 is connected to the magnetic head 54,
The magnetic head 54 is driven so that a modulation magnetic field corresponding to the recording data is applied to the magneto-optical disk 1.

The system controller 57 controls the memory 64 as described above,
By this memory control, the recording position is controlled so that the recording data read out from the memory 64 in a burst manner is continuously recorded on the recording track of the magneto-optical disk 2.
The recording position is controlled by controlling the recording position of the recording data read in a burst from the memory 64 by the system controller 57 and transmitting a control signal for designating the recording position on the recording track of the magneto-optical disk 1 to a servo control circuit. 56.

Next, the reproducing system of the magneto-optical disk recording / reproducing unit will be described. This reproducing system is for reproducing the recorded data continuously recorded on the recording tracks of the magneto-optical disk 1 by the recording system described above.
A decoder 71 is provided, in which a reproduction output obtained by tracing a recording track of the magneto-optical disk 1 with a laser beam by the optical head 53 is binarized by the RF circuit 55 and supplied. At this time, not only a magneto-optical disk but also a read-only optical disk similar to a compact disk (CD) can be read.

The decoder 71 corresponds to the encoder 65 in the above-described recording system, and performs the above-described decoding processing for error correction and EFM decoding on the reproduced output binarized by the RF circuit 55. Processing such as processing is performed to reproduce audio data at a transfer rate of 75 sectors / sec, which is faster than the normal transfer rate. This decoder 7
1 is supplied to the memory 72.

In the memory 72, data writing and reading are controlled by the system controller 57, and reproduced data supplied from the decoder 71 at a transfer rate of 75 sectors / second is written in a burst at the transfer rate of 75 sectors / second. It is. Also, in the memory 72, the reproduced data written in a burst at the transfer rate of 75 sectors / second is a regular transfer rate of 18.75 of 75 sectors / second.
It is read continuously at sectors / second.

The system controller 57 writes the reproduced data to the memory 72 at a transfer rate of 75 sectors / sec.
Memory control is performed such that data is read continuously at a transfer rate of 5 sectors / second. Further, the system controller 57 performs the above-described memory control on the memory 72, and reproduces the reproduction data written in a burst from the memory 72 by the memory control from the recording track of the magneto-optical disk 1 continuously. Control the playback position. This playback position control is performed by the system controller 5.
7 controls the reproduction position of the reproduction data read out from the memory 72 in a burst manner, and supplies a control signal specifying the reproduction position on the recording track of the magneto-optical disk 1 or the optical disk 1 to the servo control circuit 56. Done.

ATC audio data obtained as reproduction data continuously read from the memory 72 at a transfer rate of 18.75 sectors / sec is supplied to an ATC decoder 73. The ATC decoder 73 decrypts the encryption using the encryption key supplied from the system controller 57, and reproduces 16-bit digital audio data by expanding the ATC data by four times (bit expansion). I do. The digital audio data from the ATC decoder 73 is supplied to a D / A converter 74.

The D / A converter 74 includes an ATC decoder 73
Is converted into an analog signal, and an analog audio output signal Aout To form The analog audio signal Aout obtained by the D / A converter 74 Is output from an output terminal 76 via a low-pass filter 75.

A digital signal encoding apparatus as shown in FIG. 1 is used for the encoder 63 in FIG. 2, and an embodiment of the present invention as shown in FIG. Is used.

Returning to FIG. 1, the high-efficiency compression encoding to which the encryption technique is applied in the digital signal encoding apparatus and method according to the embodiment of the present invention will be described in detail. That is, an input digital signal such as an audio PCM signal is subjected to high-efficiency encoding using techniques such as band division encoding (SBC), adaptive conversion encoding (ATC), adaptive bit allocation, and encryption using an encryption key. The following describes the technique to be performed.

In the specific high-efficiency coding apparatus shown in FIG. 1, in the steady state, the input digital signal is divided into a plurality of frequency bands, and at the same time, the lowest two adjacent bands have the same bandwidth. In the high frequency band, the higher the frequency band, the wider the bandwidth is selected, the orthogonal transform is performed for each frequency band, and the obtained spectrum data on the frequency axis is used in the low frequency band. Bits are adaptively allocated and encoded for each critical bandwidth (critical band) and for each of the subdivided critical bandwidths in consideration of block floating efficiency in the middle and high ranges. Usually, this block is a quantization noise generating block. The critical band is a frequency band divided in consideration of human auditory characteristics, and a band of the noise when the pure sound is masked by a narrow band noise of the same strength near the frequency of the pure sound. That is. The bandwidth of this critical band increases as the frequency band increases, and the entire frequency band of 0 to 22 kHz is divided into, for example, 25 critical bands.

That is, in FIG.
For example, when the sampling frequency is 44.1 kHz,
An audio PCM signal of 0 to 22 kHz is supplied. This input signal is divided into a band of 0 to 11 kHz and a band of 11 kHz to 22 kHz by a band dividing filter 201 such as a so-called QMF filter.
The signal in the Hz band is also divided into a band of 0 to 5.5 kHz and a band of 5.5 kHz to 11 kHz by a band dividing filter 202 such as a so-called QMF filter. The signal in the band of 11 kHz to 22 kHz from the band division filter 201 is sent to the MDCT circuit 203 which is an example of the orthogonal transformation circuit, and the signal of 5.5 kHz to 22 kHz from the band division filter 202 is output.
The signal in the 11 kHz band is sent to the MDCT circuit 204,
The signals in the 0 to 5.5 kHz range from the band division filter 202 are sent to the MDCT circuit 205 to be subjected to MDCT processing.

Here, a QMF filter as a method for dividing the input digital signal into a plurality of frequency bands is described in 1976, R. E. FIG. Crochiere, Di
digital Coding of Speech In
Subbands, Bell Syst. Tec
h. J. Vol. 55, No. 8 1976. Also, ICASPSP 83, Bost
on, Polyphase Quadrature
Filters-A New Subband C
OddingTechnique, Joseph
H. Rothweiler describes an equal bandwidth filter division technique. In addition, the input digital signal can be divided into a plurality of frequency bands by various methods.

Further, as the above-described orthogonal transform, for example, an input audio signal is divided into blocks in a predetermined unit time (frame), and a fast Fourier transform (F
FT), cosine transform (DCT), modified DC
There is an orthogonal transformation that transforms a time axis into a frequency axis by performing a T transformation (MDCT) or the like. Regarding the above MDCT, ICASSP 1987, Subband / Transform Coding Using Fi
lter Bank Designs Based OnTime Domain Aliasing Can
cellation, JPPrincen, ABBradley, Univ. of Surr
ey Royal Melbourne Inst. Of Tech.

Here, each of the MDCT circuits 203, 204,
FIG. 3 shows a specific example of a standard input signal for a block for each band supplied to 205. In the specific example of FIG. 3, the three filter output signals each have a plurality of orthogonal transform block sizes independently for each band,
The time resolution can be switched according to the time characteristics and frequency distribution of the signal. If the signal is quasi-stationary in time, the orthogonal transform block size is increased to 11.6 ms, that is, (a) Long Mode in FIG. 3, and if the signal is non-stationary, the orthogonal transform The block size is further divided into two and four. (B) Shor in FIG.
As in the case of t Mode, when all are divided into 2.9 ms in four divisions, (c) Middle Mode A, (d) Middle Mode in FIG.
As in Mode B, one part is divided into 5.8mS and one part is divided into 4
The division at a time resolution of 2.9 ms adapts to an actual complex input signal. It is obvious that the division of the orthogonal transform block size is more effective if a more complicated division is performed if the scale of the processing device permits.

The block size is determined by the block size determination circuits 206, 207, and 208 in FIG.
T circuits 203, 204, 205, adaptive bit allocation coding circuits 210, 211, 212, and encryption circuit 219,
220 and 221, the window function (window shape) for orthogonal transformation is also determined, and the MDCT circuit 20
3, 204 and 205.

Next, FIG. 4 is a block circuit diagram showing a schematic configuration of a specific example of the block size determining circuit. Here, the block determination circuit 206 in FIG. 1 will be described as an example. Of the outputs of the QMF 201 in FIG.
The output of 1 kHz to 22 kHz is input terminal 4 in FIG.
01 to the power calculation circuit 404. Further, among the outputs of the QMF 202 in FIG.
The output of Hz to 11 kHz is input terminal 402 in FIG.
To the power calculation circuit 405, and the output of 0 to 5.5 kHz is sent to the power calculation circuit 406 via the input terminal 403 in FIG.

The block size determination circuits 207 and 208 shown in FIG. 1 correspond to the input terminals 401 and 4 shown in FIG.
The operation is the same, except that the signals input to 02 and 403 are different from those of the block size determination circuit 206. The input terminals 401, 402, and 303 in each of the block size determination circuits 206, 207, and 208 have a matrix configuration. That is, the input terminal 401 of the block size determination circuit 207 is
Outputs of 5.5 kHz to 11 kHz are connected to the input terminal 402, and outputs of 0 to 5.5 kHz are connected to the input terminal 402. The same applies to the block size determination circuit 208.

In FIG. 4, each power calculation circuit 404,
Reference numerals 405 and 406 determine the power of each frequency band by integrating the input time waveform for a certain period of time. At this time, the time width for integration needs to be equal to or smaller than the minimum time block among the orthogonal transform block sizes described above. In addition to the above calculation method, the same effect can be obtained by using, for example, the absolute value or the average value of the maximum amplitude within the minimum time width of the orthogonal transform block size as the representative power. The output of the power calculation circuit 404 is the change extraction circuit 4
08 and the power comparison circuit 409
The outputs of 5, 406 are sent to a power comparison circuit 409, respectively. In the variation extraction circuit 408, the power calculation circuit 40
Then, a differential coefficient of the power sent from step 4 is obtained and sent to the block size primary determination circuit 410 and the memory 407 as power change information.

In the memory 407, a change extraction circuit 408
The transmitted power change information is stored for the maximum time of the orthogonal transform block size or more. This is because the temporally adjacent orthogonal transform blocks mutually influence each other by window processing at the time of orthogonal transform, so that the power change information of the immediately preceding temporally adjacent block is determined by the block size primary determination circuit 410. It is necessary.

In the block size primary determination circuit 410, the power change information of the corresponding block sent from the change extraction circuit 408 and the power change information of the block immediately before the temporally adjacent corresponding block sent from the memory 407. , The orthogonal transform block size of the corresponding frequency band is determined from the temporal displacement of the power in the corresponding frequency band. At this time, when a displacement equal to or more than a certain value is recognized, a shorter orthogonal transform block size is selected. However, even if the displacement point is fixed, the effect can be obtained. Furthermore, a value proportional to the frequency, that is, if the frequency is high, a large displacement results in a temporally short block size,
When the frequency is low, it is more effective if the block size is determined to be short in time with a small displacement as compared with the case where the frequency is high. This value desirably changes smoothly, but may be a stepwise change in a plurality of stages.
The block size determined as described above is transmitted to the block size correction circuit 411.

On the other hand, in the power comparing circuit 409, the power information of each frequency band sent from each of the power calculating circuits 404, 405, and 406 is compared at the same time and the time width on which the masking effect occurs on the time axis. The influence of another frequency band on the output frequency band of the power calculation circuit 404 is obtained and transmitted to the block size correction circuit 411. In the block size correction circuit 411, the masking information and delay group 41 sent from the power comparison circuit 409
Block size primary determination circuit 4 based on past block size information sent from each of the taps 2, 413, and 414.
The block size sent from 10 is modified to select a longer block size, and the delay 41
2 and the window shape determination circuit 415.
The effect of the block size correction circuit 411 is that, even when a pre-echo is a problem in the relevant frequency band, if a signal having a large amplitude exists in another frequency band, particularly in a band lower than the relevant frequency band, the masking effect is obtained. Pre-echo does not cause a problem in hearing,
Alternatively, it utilizes the characteristic that the problem may be reduced.

The above-mentioned masking is a phenomenon in which a certain signal masks another signal and makes it inaudible due to human auditory characteristics. This masking effect is caused by an audio signal on a time axis. There are a time axis masking effect and a simultaneous masking effect by a signal on the frequency axis. Due to these masking effects, even if there is noise in the masked portion, this noise will not be heard. For this reason, in an actual audio signal, noise within the masked range is regarded as acceptable noise.

Next, the delay groups 412, 413, 414
Then, the past orthogonal transform block sizes are sequentially recorded, and each tap, that is, the delay groups 412, 413,
From the output of 414, it is output to the block size determination circuit 411. At the same time, the output of the delay 412 is connected to the output terminal 417, and the outputs of the delay groups 412 and 413 are connected to the window shape determination circuit 415. The outputs from the delay groups 412, 413, and 414 serve to use the block size correction circuit 411 to determine a change in the block size over a longer time period to determine the block size of the corresponding block. When the size is selected, the selection of the block size with a short time is increased, and when the block size with the long time is not selected in the past, the selection of the block size with a long time is increased. Judgment is possible. It should be noted that this delay group is a delay 41 necessary for the window determination circuit 415 and the output terminal
Except for 2,413, the number of taps may be increased or decreased depending on the actual configuration and scale of the device.

In the window shape determination circuit 415, the output of the block size correction circuit 411, that is, the output of the next succeeding block size of the relevant block and the delay 412, ie, the block size of the relevant block and the delay 413 , I.e., the size of the immediately preceding block adjacent to the corresponding block, from the MDCT circuits 203, 204, and 20 in FIG.
5 to determine the shape of the window to be used and output it to the output terminal 416. The output terminal 417 in FIG.
That is, the block size information and the output terminal 416, that is, the window shape information, are connected to each unit as outputs of the block size determination circuits 206, 207, and 208 in FIG.

Here, the window shape determined by the window shape determining circuit 415 will be described.
FIG. 5 shows a specific example of the shape of the adjacent block and window. As can be seen from FIGS. 5 (a) to 5 (c),
As shown by a dotted line and a solid line in the figure, the window used for the orthogonal transformation has a portion that overlaps with the temporally adjacent block, and in this embodiment, a shape that overlaps with the center of the adjacent block is adopted. Therefore, the shape of the window changes depending on the orthogonal transform size of the adjacent block.

FIG. 6 shows a specific example of the details of the window shape. In FIG. 6, window functions f (n) and g (n + N)
Is given as a function satisfying the following equation (1). f (n) × f (L-1-n) = g (n) × g (L-1-n) f (n) × f (n) + g (n) × g (n) = 1 (1) 0 ≦ n ≦ L−1 L in the equation (1) is the conversion block length as long as the adjacent conversion block lengths are the same, but is shorter if the adjacent conversion block lengths are different. Let L be the conversion block length and K be the longer conversion block length in a region where windows do not overlap, given by the following equation (2). f (n) = g (n) = 1 K ≦ n ≦ 3K / 2−L / 2 f (n) = g (n) = 0 3K / 2 + L ≦ n ≦ 2K (2) By making the overlapping portion of the window as long as possible, the frequency resolution of the spectrum at the time of orthogonal transformation is improved.

As is apparent from the above description, the shape of the window used for the orthogonal transform is determined after the orthogonal transform size of three temporally continuous blocks is determined. Therefore, the block of the signal input from the input terminals 401, 402 and 403 and the block of the signal output from the output terminals 416 and 417 in FIG.
There is a difference for blocks.

The power calculation circuit 40 shown in FIG.
5 and 406 and the power comparison circuit 409 are omitted in FIG.
Block size determination circuits 206, 207, and 20
8 is possible. Further, by fixing the shape of the window to the smallest temporal block size that the orthogonal transform block can take, the type is made one, and the delay groups 412, 413, and 414, the block size correction circuit 411, and the window shape shown in FIG. It is also possible to omit the determination circuit 415. Particularly, in an application example in which a delay in the processing time is not desired, the above-described omission causes a configuration with a small delay, which effectively operates.

Referring again to FIG. 1, each MDCT circuit 20
The spectrum data or MDCT coefficient data on the frequency axis obtained by the MDCT processing in 3, 204 and 205 are applied to adaptive bit allocation coding circuits 210, 211 and 21.
3 and transmitted to the bit allocation calculation circuit 209.

The bit allocation calculation circuit 209 obtains a masking amount for each divided band in consideration of the critical band based on the spectrum data divided in consideration of the above-described critical band, in consideration of a so-called masking effect. The number of bits to be allocated is determined for each band based on the energy or the peak value of each divided band in consideration of the masking amount and the critical band, and is transmitted to the adaptive bit allocation encoding circuits 210, 211, and 212. The adaptive bit allocation encoding circuits 210, 211, and 212 quantize each spectrum data (or MDCT coefficient data) according to the number of bits allocated to each band. The data thus encoded is sent to the encryption circuits 219, 220, 221.

Next, FIG. 7 shows the bit allocation calculating circuit 20.
9 is a block circuit diagram illustrating a schematic configuration of one specific example of Ninth Embodiment 9. FIG.
The operation of the bit allocation calculation circuit will be described with reference to FIG.

In FIG. 7, an input terminal 701 has
Spectral data on the frequency axis or MDCT coefficient data is supplied from the MDCT circuits 203, 204, and 205 in FIG. The input data on the frequency axis is sent to the energy calculation circuit 702 for each band, and the energy of each divided band in consideration of the masking amount and the critical band and block floating is, for example, the amplitude of each amplitude value in the band. It is obtained by calculating the sum. Instead of this energy for each band,
A peak value, an average value, or the like of the amplitude value may be used.
As an output from the energy calculation circuit 702, for example, the spectrum of the sum of each band is shown as SB in FIG. However, in FIG. 8, for simplicity of illustration, the number of divided bands in consideration of the masking amount, the critical band, and the block floating is represented by 12 bands (B _{1 to} B ₁₂ ).

Here, in order to consider the influence of the spectrum SB on so-called masking, a convolution (convolution) process is performed in which the spectrum SB is multiplied by a predetermined weighting function and added. Therefore, the output of the energy calculation circuit 702 for each band, that is, each value of the spectrum SB, is sent to the convolution filter circuit 703. The convolution filter circuit 703 includes, for example, a plurality of delay elements for sequentially delaying input data and a plurality of multipliers (for example, 25 corresponding to each band) for multiplying an output from these delay elements by a filter coefficient (weighting function). Multipliers) and a sum adder for summing the outputs of the multipliers. By this convolution processing, the sum of the parts indicated by the dotted lines in FIG. 8 is obtained.

Here, a specific example of the multiplication coefficient (filter coefficient) of each multiplier of the convolution filter circuit 703 will be described. When the coefficient of the multiplier M corresponding to an arbitrary band is 1, M-1 has a coefficient of 0.15, multiplier M-2 has a coefficient of 0.0019, and multiplier M-3 has a coefficient of 0.00000.
086, a coefficient 0.4 by a multiplier M + 1, and a multiplier M + 2
Is multiplied by the coefficient 0.06 by the multiplier M + 3 and the coefficient 0.007 by the multiplier M + 3, thereby performing the convolution processing of the spectrum SB. Here, M is an arbitrary integer of 1 to 25.

Next, the output of the convolution filter circuit 703 is sent to a subtractor 704. The subtractor 704 calculates a level α corresponding to an allowable noise level described later in the convolved area. The level α corresponding to the permissible noise level (permissible noise level) becomes an allowable noise level for each of the critical bands by performing inverse convolution processing as described later. Level. here,
The subtractor 704 is supplied with an allowance function (a function expressing a masking level) for obtaining the level α. The level α is controlled by increasing or decreasing the allowable function. The permissible function is supplied from the (n-ai) function generation circuit 705 described below.

That is, the level α corresponding to the allowable noise level can be obtained by the following equation (3), where i is a number sequentially given from the lower band of the critical band. α = S− (n−ai) (3) In the equation (3), n and a are constants, a> 0, S is the intensity of the convolution-processed bark spectrum, and (3)
In the expression, (n-ai) is the allowable function. In the present embodiment, n = 38, a = 1 (4), and there was no sound quality deterioration at this time, and good coding was performed.

Thus, the level α is obtained, and this data is transmitted to the divider 706. The divider 706 is for performing inverse convolution of the level α in the convolved region. Therefore, by performing this inverse convolution processing, a masking spectrum can be obtained from the level α. That is, this masking spectrum becomes an allowable noise spectrum. Although the above inverse convolution processing requires a complicated operation, the inverse convolution is performed using the simplified divider 706 in this embodiment.

Next, the masking spectrum is transmitted to a subtractor 708 via a synthesis circuit 707. Here, the output from the energy detection circuit 702 for each band, that is, the spectrum S
B is supplied via a delay circuit 709. Accordingly, the subtraction operation of the masking spectrum and the spectrum SB is performed by the subtracter 708, so that the spectrum SB is masked below the level indicated by the level of the masking spectrum MS as shown in FIG. Become.

The output from the subtracter 708 is taken out via an allowable noise correction circuit 710 and an output terminal 711. For example, an RO in which information on the number of bits to be allocated is stored in advance.
M and the like (not shown). The ROM or the like assigns each band according to the output (the level of the difference between the energy of each band and the output of the noise level setting means) obtained from the subtraction circuit 708 via the allowable noise correction circuit 710. Outputs bit number information. This information on the number of allocated bits is used as the adaptive bit allocation coding circuits 210 and 21 in FIG.
1 and 212, each spectrum data on the frequency axis from the MDCT circuits 203, 204 and 205 in FIG. 1 is quantized by the number of bits assigned to each band.

That is, in summary, in the adaptive bit allocation coding circuits 210, 211 and 212 shown in FIG. Then, the spectrum data for each band is quantized by the number of bits allocated according to the level of the difference from the above. Note that the delay circuit 7 in FIG.
Reference numeral 09 is provided to delay the spectrum SB from the energy detection circuit 702 in consideration of the amount of delay in each circuit before the synthesis circuit 707.

By the way, at the time of synthesizing by the synthesizing circuit 707, data indicating a so-called minimum audible curve RC which is a human auditory characteristic as shown in FIG. The masking spectrum MS can be synthesized. At this minimum audible curve, if the absolute noise level is below this minimum audible curve, the noise will not be heard. This minimum audible curve will be different depending on the reproduction volume at the time of reproduction, for example, even if the coding is the same, but in a realistic digital system, for example, when music is entered into the 16-bit dynamic range, Since there is not much difference, if quantization noise in the most audible frequency band around 4 kHz is not heard, for example, it is considered that quantization noise below the level of the minimum audible curve is not heard in other frequency bands. . Therefore, assuming that the system is used so that noise around 4 kHz of the word length of the system cannot be heard, and an allowable noise level is obtained by synthesizing the minimum audible curve RC and the masking spectrum MS together, In this case, the allowable noise level can be up to the shaded portion in FIG. In the present embodiment, the 4 kHz level of the minimum audible curve is adjusted to the lowest level corresponding to, for example, 20 bits. FIG. 10 also shows the signal spectrum SS.

In the allowable noise correction circuit 710,
The allowable noise level in the output from the subtractor 708 is corrected based on, for example, information on the equal loudness curve sent from the correction information output circuit 713, and the output terminal 71
1 via the encryption circuits 219, 220,
221. Here, the equal loudness curve is a characteristic curve relating to human auditory characteristics, for example, 1
The sound pressure of sound at each frequency that sounds as loud as the pure tone of kHz is obtained and connected by a curve, and is also called a loudness iso-sensitivity curve. This equal loudness curve is shown in FIG.
It draws substantially the same curve as the minimum audible curve RC shown in FIG. In this equal loudness curve, for example, 4k
In the vicinity of 1 Hz, the sound pressure is 8 to 10 dB from 1 kHz
Even if it goes down, it sounds as big as 1 kHz,
In the vicinity of Hz, the sound cannot be heard at the same level unless it is higher than the sound pressure at 1 kHz by about 15 dB. Therefore, the noise exceeding the level of the minimum audible curve (allowable noise level)
It can be seen that it is better to have a frequency characteristic given by a curve corresponding to the equal loudness curve. From this, it can be seen that correcting the allowable noise level in consideration of the equal loudness curve is suitable for human auditory characteristics.

Further, the correction information output circuit 713 detects the output information amount (data amount) at the time of quantization in the adaptive bit allocation encoding circuits 210, 211 and 212, and outputs the bit rate target value of the final encoded data. The permissible noise level is corrected based on the information on the error between the two. This is because the total number of bits obtained by previously performing temporary adaptive bit allocation for all the bit allocation unit blocks becomes a fixed number of bits (target value) determined by the bit rate of the final encoded output data. In some cases, there is an error, and bit allocation is performed again so that the error is set to zero. That is, when the total number of allocated bits is smaller than the target value, the number of difference bits is allocated to each unit block and added. It works by allocating to and shaving.

In order to perform the above operation, an error in the total number of allocated bits from the target value is detected, and a correction information output circuit 713 corrects each number of allocated bits in accordance with the error data. Output data. Here, when the error data indicates that the number of bits is insufficient, it is possible to consider a case where the data amount is larger than the target value by using a large number of bits per unit block. When the error data is data indicating the surplus of bits, it is possible to consider a case where the number of bits per unit block is small and the data amount is smaller than the target value. Therefore, from the correction information output circuit 713, according to the error data, the allowable noise level in the output from the subtracter 708 is corrected based on, for example, the equal loudness curve information data. Data will be output. By transmitting the correction value as described above to the allowable noise correction circuit 710, the allowable noise level from the subtractor 708 is corrected.

In the system described above, data obtained by quantizing the orthogonal transform output spectrum as main information is used.
The word length indicating the word length of the quantization and the block size of the orthogonal transform are obtained as the data and the sub information, and the encryption circuits 219, 220, 221, 223, 224, and 2 in FIG.
25.

In FIG. 1 again, the encryption circuit 219 includes a spectrum obtained by orthogonally transforming the spectrum transmitted from the adaptive bit assignment coding circuit 210 or data obtained by quantizing coefficients subjected to MDCT processing and a word indicating the word length of quantization. The length is encrypted using data for encryption transmitted from the encryption key control circuit 222, that is, a so-called encryption key, and the output terminal 213 is used.
Output to

The encryption circuit 223 includes the block determination circuit 20
6, the block size information for the orthogonal transformation transmitted from the encryption key control circuit 222,
The data is encrypted using a so-called encryption key and output to the output terminal 216.

Similarly, the encryption circuit 220 uses the adaptive bit allocation coding circuit 211 and the encryption key control circuit 222, and the encryption circuit 221 uses the adaptive bit allocation coding circuit 212 and the encryption key control circuit 222 to generate the encryption circuit 224. Is from the block determination circuit 207 and the encryption key control circuit 222, and the encryption circuit 225 is the block determination circuit 208 and the encryption key control circuit 22.
2, and receives data from output terminals 214, 215,
217 and 218, respectively.

Next, FIG. 11 shows the encryption circuits 210, 2
It is a block circuit diagram which shows the schematic structure of one specific example of 11,212,223,224,225. The operation of the encryption circuit will be described with reference to FIG.

FIG. 11 shows a 6-bit encryption key using a 56-bit encryption key.
Data input every 4 bits is encrypted by performing 16-stage processing. The input terminal 301 in FIG. 11 is connected to the adaptive bit allocation encoding circuits 210, 211, 212 in FIG.
Alternatively, it is connected to the outputs of the block decision circuits 206, 207 and 208, and the adaptive bit allocation encoding circuits 210 and 2
11 or 212, orthogonally transformed spectrum or data obtained by quantizing coefficients subjected to MDCT processing and word length indicating the word length of quantization, or orthogonal transformation transmitted from block determination circuits 206, 207 and 208. Is transmitted. The data input from the input terminal 301 is divided into left and right 32 bits at a time after the order of the bits is changed by the initial value conversion circuit 302. Subsequently, the right 32 bits x1 are stored in the F function circuit 3
After being processed in 03, the left 32 bits are XORed with the exclusive OR circuit 319, and the left and right 32 bits are exchanged and sent to the next stage. Hereinafter, the encryption process is performed by repeating the same process 16 times. The 32-bit left and right data after the completion of the 16-stage processing is transferred to the initial transposition circuit 3
02 is replaced by a final transposition circuit 335 composed of an inverse function of the output terminal
6 is output.

The input terminal 338 in FIG.
It is connected to the output of the encryption key control circuit 222 in FIG. 1 and receives a so-called encryption key for encryption. In this embodiment, this encryption key has a word length of 56 bits. 56 input from the input terminal 338
The key encryption unit 337 generates a 5-bit encryption key
Six bits are expanded to 768 bits, and are transferred to each of the F function circuits 303 to 318 by 48 bits for each stage.

FIG. 12 is a block circuit diagram showing a schematic configuration of one specific example of the F function circuits 303 to 318 in FIG. The operation of the F function circuit will be described with reference to FIG.

The input terminal 501 in FIG.
, And the 48-bit data ki expanded from 56 bits to 768 bits is input. The 48-bit data is divided into 6-bit units, and the exclusive-OR circuits 504 to
511. On the other hand, the right 32-bit data X of the data divided into left and right 32 bits in FIG. 11 is input from the input terminal 502 in FIG. Logical OR is performed. The output of each of the exclusive OR circuits 504 to 511 is an S-BOX composed of a permutation table.
The signals are input to circuits 512 to 519. Each of the S-box circuits 504 to 511 converts a 6-bit input according to a conversion table and outputs 4-bit data. Therefore, a total of 3 output from the eight s-box circuits 512 to 519
The 2-bit data is input to the transposition circuit 520. In the transposition circuit 520, the order of the bits is changed and output from the output terminal 521 as F (x, k).

Referring again to FIG. 1, encryption key control circuit 222
Is input via the input terminal 226 in FIG.
An encryption key necessary for each of the encryption circuits 219, 220, and 221 is generated and transmitted based on a so-called encryption key and information for encryption transmitted from the system controller 57 in FIG. Here, as the information for the encryption, for example, the outputs of all the adaptive bit allocation coding circuits are encrypted with the same encryption key, only the output of the adaptive bit allocation coding circuit 210 is encrypted, Selection control information, such as encrypting all outputs of the adaptive bit allocation encoding circuit with a different encryption key, or permitting only an encryption / decryption circuit having a specific decryption key to decrypt the encryption. .

Next, FIG. 13 is a block circuit diagram showing a schematic configuration of one specific example of the encryption key control circuit 222 in FIG. The operation of the encryption key control circuit will be described with reference to FIG.

The input terminal 601 in FIG. 13 is connected to the input terminal 226 in FIG. 1, and the so-called encryption key and information for encryption transmitted from the system controller 57 in FIG. 1 are input. The information for encryption includes, for example, encrypting the outputs of all adaptive bit allocation encoding circuits with the same encryption key, encrypting only the output of adaptive bit allocation encoding circuit 210, all adaptive bit allocation Information such as encrypting all outputs of the encoding circuit with different encryption keys, or permitting decryption of encryption only by an encryption / decryption circuit having a specific decryption key. Among such information, information such as permitting decryption of encryption only by a so-called encryption key and an encryption / decryption circuit having a specific decryption key is the encryption key generation circuit 6 in FIG.
02, 603 and 604. In the present embodiment, the encryption key is expressed with a word length of 64 bits for convenience, and the encryption key generation circuits 602, 603, and 604 convert the encryption key to a word length of 56 bits according to the corresponding encryption / decryption circuit. And transferred to the switch circuits 607 to 615. Further, the information for encryption input from the input terminal 601 is input to the encryption key generation circuit 606 in FIG. 13 and is decoded into a signal of 1 bit, and the output of each encryption key generation circuit 602, 603, 604 and , Empty key generation circuit 6
05 and the disconnection of the switch circuits 607 to 618 connected to the output terminals 619, 620, and 621. Also, the empty encryption key generation circuit 605 includes the encryption circuits 219, 220, 221, 223, and 22 in FIG.
4 and 225, an encryption key that can obtain the same output as the input data.
17 and 618. Switch circuits 607-6
At 18, the input data is selectively output to the output terminal 61 according to the control data output from the encryption control circuit 606.
9, 620, and 621. The output terminal 619 is connected to the encryption circuits 219 and 225 in FIG.
20 is connected to the encryption circuits 220 and 224 in FIG. 1, and the output terminal 621 is connected to the encryption circuits 221 and 225 in FIG.

Here, the operation of the switch circuits 607 to 618 will be described. For example, if encryption of all outputs of the adaptive bit allocation encoding circuits 210, 211, 212 and the block determination circuits 206, 207, 208, that is, data of all bands is not performed, the switch circuit 616, The output circuits 619, 620, and 621 output a so-called empty encryption key that is not encrypted by controlling the connection of the switches 617 and 618 and the connection of the other switch circuits so as not to be connected. Also, the adaptive bit allocation encoding circuit 21 shown in FIG.
2, when only the output of the block determination circuit 208, that is, the data in the high band (11 kHz to 22 kHz) is encrypted, the switch circuits 607, 617, and 618 are controlled to be connected. Similarly, the outputs of the adaptive bit allocation coding circuits 211 and 212 and the block determination circuits 207 and 208 in FIG.
In the case of encrypting data of z to 11 kHz and 11 kHz to 22 kHz), when performing encryption using different encryption keys, the switch circuits 607, 611, and 618 are used.
However, when the same encryption key is used, the switch circuit 60
7, 608, 618 to 610, 611, 618 or 613, 614, 618 are controlled to be connected. Further, when encrypting data of all bands and encrypting with the same encryption key, the switch circuits 607, 608, 609 to 610, 611,
When 612 or 613, 614, and 615 encrypt all data in all bands with different encryption keys, control is performed so that the switch circuits 607, 611, and 615 are connected. By controlling the switch circuits 607 to 618 in this manner, all combinations of the divided bands and the encryption in the high-efficiency coding can be realized.

Next, FIG. 14 shows a specific example of the bit stream after performing the high-efficiency encoding and encryption processing in the present embodiment. The operation of the encoding according to the present embodiment will be described with reference to FIG.

In FIG. 14, in (A), all plain text,
(B) shows an example of a bit stream when only the high band is encrypted, (C) shows a case where the middle and high band are encrypted, and (D) shows an example of a bit stream when the entire band is encrypted.

As shown in FIG. 14 (A), when plain text is used without encryption, so-called main data obtained by quantizing each of the orthogonally transformed output spectra of low, medium and high, and the word length of quantization are represented by The indicated word length and so-called sub information indicating the block size of the orthogonal transform and the like are recorded or transmitted. That is, as the main information, the low-frequency main information 711, the middle-frequency main information 721, and the high-frequency main information 73
1 as low-frequency sub-information 712, middle-frequency sub-information 722, and high-frequency sub-information 732. In the case of (A), when decoding, the main information of the corresponding band is decoded using the sub-data of the corresponding band according to the procedure of the decoder described later.

On the other hand, as shown in FIG.
If only the high-frequency main data is encrypted, pseudo high-frequency sub-information 735 such that the high-frequency main information becomes invalid is written in the portion where the high-frequency sub-information is to be recorded. Is encrypted together with the high-frequency main information and written into the high-frequency main information. That is, the encrypted high-frequency main information 733 and the encrypted high-frequency sub-information 734 are stored in the original high-frequency main information area.
Is written.

Therefore, a receiver who has no means for decrypting the encryption, or a receiver who does not have an encryption key for decrypting the encryption, receives low-mid range data (0 kHz to 11 kHz).
Only z) can be decoded. At this time, since the high-frequency main information is encrypted, the above-mentioned receiver cannot be significant information for decryption, but the pseudo high-frequency sub-information invalidating the high-frequency main information The operation of 735 does not hinder the decoding of the low middle band information. Also, like this,
If high-frequency data that should be present is not decoded, theoretically, aliasing noise generated at the time of band division in the QMF circuits 201 and 202 in FIG. 1 cannot be canceled at the time of synthesis. The quality of the speech information obtained was not significantly impaired.

Further, when only the high frequency band is encrypted as shown in FIG. 14 (B), the receiver has a means of plaintext encryption and a cryptographic key for plaintext encryption. In this case, the data recorded in the encrypted portion shown in FIG.

According to the above arrangement, the receiver who does not have the means for decrypting the encryption or the encryption key for decrypting the encryption partially decrypts the data and then transmits the encryption to the sender. Even if a means for flattening or an encryption key for flattening is requested and obtained, the previously obtained partially encrypted data can be obtained without transferring the encrypted high-efficiency encoded data again. It is possible to decrypt and decode the encoded data with high efficiency.

Next, FIG. 14C shows a case in which the data of the middle and high frequencies are encrypted, and the encrypted high-frequency main information 73 is stored in the area of the original high-frequency main information and the middle-frequency main information.
3. Encrypted high band sub information 734, encrypted middle band main information 723, encrypted middle band sub information 724
Are respectively arranged, and pseudo high frequency sub-information 735 and pseudo mid frequency sub-information 7
25 are arranged respectively.

As in the example of FIG. 14C, even when the data in the middle and high frequency bands is encrypted, the same operation and effect as in the case of the above-mentioned (B) are obtained. In addition, in the configuration as shown in (C), the encryption key for encrypting the middle band data and the encryption key for encrypting the high band data can be different from each other. The caller has more options: only one encrypted high-efficiency coded data, only low-frequency encoding, low-mid encoding possible,
It is possible to provide the receiver with the option that the entire band can be decrypted, or use only one encrypted high-efficiency encoded data as an encryption key to split the encryption owned by the receiver. Accordingly, it is possible to specify the quality of the audio data at the time of decoding and deliver the data.

Further, in the example shown in FIG. 14 (D), the data of the entire band is encrypted, and the area of the original main information has the encrypted high-frequency main information 733 and the encrypted high-frequency main information 733. Sub information 734, encrypted middle area main information 72
3. Encrypted middle band sub information 724, encrypted low band main information 713, encrypted low band sub information 714
Are respectively arranged, and pseudo high frequency sub-information 735 and pseudo mid frequency sub-information 7
25, pseudo low frequency sub information 715 is arranged.

In the case of encrypting the entire band as shown in FIG. 14D, a receiver who has no means for decrypting the encryption or an encryption key for decrypting the encryption is not provided. The receiver differs from the previous case in that decryption is impossible, but the combination of the encryption key and the decryption quality of voice data in encryption and high-efficiency coding can be obtained more. Becomes That is, it is possible to select only one encrypted high-efficiency encoded data that cannot be decrypted, that only the low-frequency band can be encoded, that the low-mid frequency band can be encoded, and that all the bands can be decrypted. The quality of audio data that can be provided to the receiver, or the quality of audio data when decrypted with only one encrypted high-efficiency encoded data according to the encryption key for dividing the encryption owned by the receiver, Alternatively, delivery is possible by designating that decoding is impossible.

Similarly, in the present embodiment, MDCT circuits 203, 204 and 205 in FIG.
It is obvious that the outputs of the MF circuits 201 and 202 are orthogonally transformed every 512 samples, and that even when the above-mentioned encryption is performed, it can be controlled for each of the temporally divided small blocks.
Therefore, according to the present embodiment, it is possible to form plaintext only for a predetermined time from the beginning of the compressed data, and after a lapse of a predetermined time, to generate compressed and encrypted data.

For example, when an original input signal is used as an audio signal, only a head portion of a plurality of music pieces is set as plain text, and at least a part of a frequency band of a remaining portion is encrypted and recorded. It is conceivable to distribute a signal recording medium. In this case, the listener pays for the desired music and obtains the encryption key, so that the whole music can be reproduced with good sound quality. When such a signal recording medium is created, the encryption key and the information for encryption are changed with the lapse of the performance of the music and supplied to the input terminal 226 in FIG. I just need.

That is, a digital signal compressed and encoded by the digital signal encoding apparatus or method according to the above-described embodiment of the present invention is recorded on a recording medium such as a magneto-optical disk, an optical disk, a magnetic disk, and a magnetic tape. Thus, a signal recording medium according to an embodiment of the present invention can be obtained.

The digital signal transmission method according to the embodiment of the present invention can be realized by transmitting a digital signal compressed and encoded by the digital signal encoding device or method according to the above-described embodiment.

Next, a specific example of a digital signal decoding apparatus and method according to an embodiment of the present invention will be described with reference to FIG.
This will be described with reference to FIG.

FIG. 15 shows an example of a digital signal decoding apparatus corresponding to the digital signal encoding apparatus shown in FIG. 1, and can be used, for example, as the ATC decoder 73 in FIG. That is, FIG. 15 corresponds to FIG.
2 shows a decoding circuit for decoding again a signal which has been encrypted and highly efficiently coded by the digital signal coding apparatus of FIG.

In FIG. 15, the quantized and encrypted MDCT coefficients of each band and the word length indicating the word length of the similarly encrypted quantization, that is,
Data equivalent to the output signals of the output terminals 213, 214, and 215 in FIG.
Are input to the encryption / decryption circuits 109, 110, 111 via the input terminal 120, 121, 122 and input to the encryption / decryption circuits 112, 113, 114 via the input terminals 120, 121, 122. Is done.

FIG. 16 is a block circuit diagram showing a schematic configuration of one specific example of the encryption / decryption circuits 109 to 114 in FIG. The operation of the encryption / decryption circuit will be described with reference to FIG.

As shown in FIG. 16, the procedure of the encryption / decryption circuit according to the present embodiment is equivalent to a specific example of the encryption circuit shown in FIG. The difference between FIG. 11 and FIG. 16 is that the order of the 48-bit data output from the key schedule unit 837 to the F function circuits 803 to 818 in FIG. 16 is opposite to the order of the data output from the key schedule unit 337 in FIG. 11 in that the operation of the initial transposition circuit 302 in FIG. 11 is replaced by the final transposition circuit 835 in FIG. 16, and the operation of the final transposition circuit 335 in FIG. 11 is replaced by the initial transposition circuit 802 in FIG. It is. Therefore, the F function circuit 8 in FIG.
03 to 818 are the F function circuits 303 to 3 in FIG.
It is composed of the same circuit as 18.

Referring again to FIG. 15, an encryption key for so-called encryption and decryption and information for decryption transmitted from the system controller 57 in FIG. 1 via the input terminal 123, for example, the adaptive bit allocation in FIG. The outputs of the encoding circuits 210, 211, 212 are all encrypted with the same encryption key. Only the output of the adaptive bit allocation encoding circuit 210 in FIG. 1 is encrypted. The adaptive bit allocation encoding in FIG. Information and encryption such that the outputs of the circuits 210, 211, and 212 are all encrypted with different encryption keys, or only the decryption circuit having a specific decryption key is permitted to decrypt the encryption. The encryption key data unique to the ATC decoder 73 in FIG. 1 described in the key table 116 is input to the encryption key control circuit 115. The encryption key control circuit 115 generates and transmits an encryption key required for each of the encryption / decryption circuits 109 to 114 based on the above information.

FIG. 17 is a block circuit diagram showing a schematic configuration of one specific example of the encryption key control circuit 115 in FIG. The operation of the encryption key control circuit will be described with reference to FIG.

The input terminal 901 in FIG. 17 is connected to the input terminal 123 in FIG. 15, and has an encryption key for decrypting a so-called encryption transmitted from the system controller 57 in FIG. information,
For example, the adaptive bit allocation encoding circuit 21 in FIG.
The adaptive bit allocation encoding circuit 2 in FIG. 1 in which outputs 0, 211, and 212 are all encrypted with the same encryption key.
10 are encrypted, the outputs of the adaptive bit assignment encoding circuits 210, 211, 212 in FIG. 1 are all encrypted with different encryption keys, or are encrypted and decrypted with a specific decryption key. Only the decryption circuit receives information such as permission to decrypt the code. In this information, information that only the encryption / decryption circuit having a so-called encryption key and a specific decryption key is allowed to decrypt the encryption is shown in FIG.
Are input to the encryption key generation circuits 902, 903, and 904.

In this embodiment, the encryption key is expressed by a word length of 64 bits for convenience.
At 02, 903, and 904, the word length is converted to a 56-bit word length according to the corresponding encryption / decryption circuit, and transferred to the switch circuits 907 to 915. Also, the input terminal 90
The information for encryption / decryption input from 1 is input to the encryption key generation circuit 906 in FIG. 17 and is decoded into a signal of 1 bit unit, and each of the encryption key generation circuits 902, 903, 90
4 and the output of the empty key generation circuit 905 and the switch circuit 90 connected to the output terminals 919, 920, 921.
7 to 918 are controlled. In addition, the empty encryption key generation circuit 905 is provided in each of the encryption / decryption circuits 10 in FIG.
The output from the switches 9, 110, 111, 112, 113, and 114 outputs an encryption key to the switch circuits 916, 917, and 918 such that the same output as the input data is obtained.

The switch circuits 907 to 918 selectively output the input data to output terminals 919, 920, 92 according to the control data output from the encryption control circuit 906.
Connected to 1. The output terminal 919 is connected to the encryption / decryption circuits 109 and 112 in FIG.
Output terminals 92
1 is connected to the encryption / decryption circuits 111 and 114 in FIG. Switch circuits 907 to 91 in FIG.
The operation of the switch circuit 8 shown in FIG.
By controlling the switch circuits 907 to 918, all combinations of divided bands and encryption / decryption in high-efficiency encoding can be realized.

Referring again to FIG. 15, adaptive bit allocation decoding circuits 106, 107 and 108 release bit allocation using adaptive bit allocation information. Next, the inverse orthogonal transform (I
MDCT) circuits 103, 104, and 105 convert signals on the frequency axis into signals on the time axis. The signals on the time axis of these partial bands are decoded into full-band signals by band synthesis filter (IQMF) circuits 102 and 101.

According to the embodiment of the present invention described above, digital audio data is compressed,
When encrypting and distributing to recipients via a recording medium or a communication channel, it can be transmitted to multiple recipients without attaching unencrypted information such as a table of contents or a sample so that the recipients can select them. On the other hand, many pieces of information can be distributed at the same time, and the receiver can selectively perform decryption, or the sender can selectively permit decryption for each receiver. Further, since there is no need to select and encrypt information for each recipient and distribute it, even if the number of recipients increases, a huge amount of work is not required for distribution.

In addition, only by distributing the same data, it is possible to distribute different information such as quality, for example, a reproduction band in audio data, to each receiver. Therefore,
Since there is no need to distribute all the encrypted information for each quality, it is possible to reduce the amount of information to be distributed,
A medium for recording data compressed and encoded using the digital signal encoding apparatus and method according to the embodiment of the present invention can use storage capacity more effectively than conventional media. Furthermore, when data compressed and encoded using the digital signal encoding apparatus and method according to the embodiment of the present invention is transmitted, the line utilization efficiency can be improved as compared with the conventional one.

Next, a specific example of a digital signal encoding apparatus according to another embodiment different from the embodiment of the digital signal encoding apparatus shown in FIG. 1 will be described with reference to FIG.

FIG. 18 shows a digital signal coding apparatus according to another embodiment which is different from the high-efficiency compression coding encoder usable for the bit rate compression coding and encryption of the embodiment shown in FIG. It is a block circuit diagram which shows one specific example.

Each circuit in FIG. 18 is equivalent to each circuit indicated by the same reference numeral in FIG. However, the encryption circuits 219, 220, 221 in FIG.
Is the connection between the encryption circuits 219, 220, and 221 in FIG. 1 and other circuits, and the encryption circuits 219, 220, and 221 in FIG. 18 are connected in series. Therefore, when encrypting only the data obtained by quantizing the high-frequency orthogonal transform output spectrum as shown in FIG.
The encryption key control circuit 222 controls so that only the encryption circuit 221 in FIG. 18 is valid and the encryption circuits 220 and 221 are invalid. Similarly, when the data obtained by quantizing the orthogonal transform output spectrums of all the bands is encrypted with the same encryption key, the encryption circuits 219 and 22 are used.
0 and 221 are all valid and the same encryption key is controlled by the encryption key control circuit 222. Thus, FIG.
The effect of the present embodiment can also be realized in the ATC encoder shown in FIG.

FIG. 19 is a block circuit diagram showing a specific example of a high efficiency compression encoding decoder corresponding to the high efficiency compression encoding encoder shown in FIG. Each circuit in FIG. 19 is equivalent to each circuit indicated by the same number in FIG. However, the connection of the encryption / decryption circuits 109, 110, 111 in FIG. 19 is different from that of the corresponding encryption / decryption circuit in FIG. 15, corresponding to the ATC encoder shown in FIG. ing. Further, as described above with reference to FIG. 18, the operation of the encryption key control circuit 115 also differs in correspondence with FIG.

Next, FIG. 20 is similar to FIG. 15 and FIG.
6 is a flowchart for explaining a procedure of a decoding process in the digital signal decoding device shown in FIG.

In FIG. 20, the first step 25
In step 2, data to be decoded (encoded digital signal) is read, and in the next step 253, the presence or absence of data to be decoded is determined. If there is data to be decrypted (YES), the process proceeds to step 254, and if not (NO), the process ends. Step 254
Then, the significance of the sub data is determined, and if the sub data is significant (YES), it is not encrypted.
Decompression decoding processing after step 259, that is, decompression processing corresponding to the reverse processing of information compression, is performed. Step 254
If NO, that is, if it is determined that the sub data is not significant, the process proceeds to step 255, where it is determined whether or not there is an encryption key for decryption. If NO in step 255, that is, if it is determined that there is no encryption key, since the corresponding data cannot be decrypted, the process returns to step 252 to decrypt the next block in time. On the other hand, in the case of YES having an encryption key, the process proceeds to step 256, where the encryption key is read, and encryption and decryption are performed in the next step 257. Next, in step 258, the sub-data (sub-information) embedded in the encrypted area in the main area in FIG. 14 is restored to make the data decompressible for compression encoding, and the process proceeds to step 259. . In step 259, as described above, when the sub data is significant, that is, when the corresponding block is not encrypted, and when the encryption is decrypted in steps 255 to 258, the decompression of the compressed data is performed. Is performed, and in step 260, decompressed data is output. When the data output is completed, the process returns to step 252 to decode the next block in time.

The embodiments of the present invention described above are merely examples, and various modifications can be made without departing from the spirit of the present invention.

That is, the digital signal encoding apparatus and / or the decoding apparatus according to the embodiment of the present invention distributes an input signal into small blocks subdivided with respect to time and frequency, and compresses the signal. It has means for independently encrypting each of the subdivided small blocks, subdividing the frequency, independently encrypting each of the compressed small blocks, and displaying a plurality of decryption / decompression states with the same compressed encryption information. It has means for reproducing.

Further, the digital signal encoding apparatus and / or the decoding apparatus according to the embodiment of the present invention distributes an input signal into small blocks subdivided in time and frequency, and compresses the input signal. It has means for independently encrypting each subdivided small block, subdividing time, and independently encrypting each compressed small block,
It has means for reproducing a plurality of encryption / decryption / decompression states with the same compression / encryption information.

The digital signal encoding apparatus and / or the decoding apparatus according to the embodiment of the present invention distributes an input signal into small blocks that are subdivided in time and frequency, and compresses the input signal. It has means connected in series for multiplexly encrypting the subdivided small blocks, subdivides the frequency, subdivides the compressed subblocks individually and / or multiplexes, and uses the same compressed encryption information. And means for reproducing a plurality of decryption / decompression states.

Furthermore, the digital signal encoding apparatus and / or the decoding apparatus according to the embodiment of the present invention distributes an input signal into small blocks subdivided in time and frequency, and compresses the signal. Means connected in series for encrypting the subdivided small blocks in multiples;
Subdivided by time, compressed small blocks alone,
And / or multiplex encryption, and means for reproducing a plurality of decryption / decompression states using the same compressed / encrypted information.

Here, the digital signal encoding device and / or the decoding device according to each of the above embodiments may further have the following configuration.

That is, the time length of the processing block for information compression is made variable in accordance with the input digital signal, and the change of the input signal of the processing block and the change of the input signal of the other processing block, and / or A processing block length determining means for determining the length of the processing block based on power, energy, or peak information is provided. The time length of the processing block for information compression is made variable in accordance with the input signal, and the input signal obtained by the change of the input signal of the processing block and the input signal having the time width longer than the maximum of the processing block in time A processing block length determining means for determining the length of the processing block based on the change information.
Further, both functions of these two processing block length determining means may be combined. Further, the processing block length determining means may fix a ratio involved in determining an element for determining the length of the processing block, or a ratio adapted to an input signal and / or a predetermined ratio (for example, 2 times, 4 times, 8 times). Double)
To be used in combination or alone. Such a processing block length determining means corresponds to the block size determining circuits 206 to 208 in FIG.

The input signal is, for example, an audio signal, and the higher the frequency, the wider the frequency width of the block that controls the generation of at least most of the quantization noise.

The digital signal encoding apparatus according to the embodiment of the present invention includes orthogonal transform means (such as MDCT 203 to 205 in FIG. 1) that use orthogonal transform to divide a time axis signal into a plurality of bands on a frequency axis. ), And the digital signal decoding apparatus is provided with inverse orthogonal transform means (inverse orthogonal transform circuits 103 to 105 in FIG. 15 and the like) using inverse orthogonal transform for converting a plurality of bands on the frequency axis into a time axis signal. In addition, it is also possible to provide an orthogonal transform size and window function shape changing means for changing the orthogonal transform size in the orthogonal transform and also changing the shape of a window function used in the orthogonal transform. At this time, when dividing the time axis signal into a plurality of bands on the frequency axis, first, the signal is divided into a plurality of bands,
A block consisting of a plurality of samples is formed for each of the divided bands, orthogonal transform is performed for each block of each band to obtain coefficient data, and / or conversion from the plurality of bands on the frequency axis to a time axis signal In this case, an inverse orthogonal transform is performed for each block of each band in the conversion from a plurality of bands on the frequency axis to a time axis signal, and the outputs of the inverse orthogonal transforms are combined to obtain a combined signal on the time axis. Further, a divided frequency width in dividing the time axis signal before the orthogonal transform into a plurality of bands on the frequency axis and / or a plurality of bands in the synthesis of the time axis signal from the plurality of bands on the frequency axis after the inverse orthogonal transform. Is increased in the higher frequency range. The divided frequency width and / or the synthesized frequency width are the same in two consecutive lowest bands. Further, at the time of the above-mentioned bit allocation, the main information and / or the sub-information of the compression code may not be allocated to the signal components in the band substantially equal to or higher than the signal pass band. Note that a quadrature-mirror filter (QMF) may be used for the division into the plurality of bands and / or the conversion into a signal on the time axis composed of the plurality of bands. Using a transform (MDCT).

Further, when determining the time length of the processing block based on the change of the input signal of the processing block,
The boundary value is variable according to the amplitude and frequency of the input signal. The boundary value that determines the time length of the processing block based on the change of the input signal of the processing block is the amplitude of the input signal,
It takes a plurality of step-like values according to the frequency. The auditory characteristics of the signal of the other processing block on the signal of the processing block are calculated using the spectrum and / or the energy and / or power or peak information of the orthogonal transform coefficient on the frequency axis, and Make time length decisions. The spectrum on the frequency axis and / or the orthogonal transform coefficient used in calculating the auditory characteristic that the signal of the other processing block exerts on the signal of the processing block,
Shared with bit allocation for compression and / or orthogonal transform coefficients. Furthermore, the digital signal processing device of the present invention
The function to change the boundary value according to the amplitude and frequency of the input signal and the function to calculate the auditory characteristics using the spectrum, energy, power and peak information to determine the time length of the processing block are combined. You may have it. Furthermore, when determining the time length of the processing block based on the change of the input signal of the processing block, the determination based on the periodic change of the input signal and / or the repetitive pulse or the periodic characteristic is performed. May be performed.

Further, as an embodiment of the signal recording medium according to the present invention, there can be mentioned a recording medium of a digital signal which has been compression-encoded by the above-described digital signal encoding apparatus and method.

Further, a digital signal transmission method according to the present invention includes transmitting a digital signal compressed and encoded by the above-described digital signal encoding device and method.

According to such an embodiment of the present invention,
When a digital audio signal or the like is compressed and encrypted and distributed to a receiver via a recording medium or a communication channel, information such as an unencrypted table of contents or a sample is selected so that the receiver can select it. A large number of information can be distributed simultaneously to multiple recipients without attachment, and the recipient can selectively decrypt or the sender can selectively permit decryption for each recipient. Becomes Further, since there is no need to select and encrypt information for each recipient and distribute it, even if the number of recipients increases, a huge amount of work is not required for distribution.

In addition, only by distributing the same data, it is possible to distribute different information such as the quality, for example, the reproduction band of the audio data, to each receiver. Therefore,
A medium for recording data compressed by the digital signal processing device according to the embodiment of the present invention can be reduced because it is not necessary to distribute all pieces of encrypted information for each quality collectively. Means that the storage capacity can be used more effectively than the conventional one. Furthermore, a path for transmitting data compressed by the digital signal processing device using the embodiment of the present invention can increase the line utilization efficiency as compared with the conventional one.

The present invention is not limited to the above embodiment. For example, the above-mentioned recording / reproducing medium and a signal compression device or a decompression device, and further, a signal compression device and a decompression device are integrated. It is not necessary that the communication be performed by a data transfer line, an optical cable, communication by light or radio waves, or the like without using a recording medium. Further, for example, the present invention is applicable not only to audio PCM signals but also to signal processing devices for digital audio (speech) signals and digital video signals.

The signal recording medium according to the embodiment of the present invention is not limited to the above-described magneto-optical disk, but may be an optical disk, a magnetic disk, an IC memory, a card having the memory, a magnetic tape, or other various recording media. It can also be a medium.

[0144]

As is clear from the above description, according to the digital signal encoding apparatus and method according to the present invention,
The input digital signal is divided into small blocks subdivided in at least one of time and frequency, spectrum data on the frequency axis is obtained, and the number of bits to be allocated for compression for each of the subdivided small blocks is obtained. Encoding is performed according to the number of bits, and at least a part of the subdivided small blocks is encrypted, and an encryption key for controlling the encryption is generated. Using the encrypted data, it is possible to obtain a reproduction signal having a plurality of reproduction qualities corresponding to a plurality of encryption / decryption states.

In particular, this makes it possible to select an encryption range and an encryption key at the time of the above-mentioned encryption, and to control the encryption according to the encryption key and the passage of time. The frequency band that can be decrypted can be made different depending on the encryption key, or the range that can be decrypted can be changed over time.

Therefore, when coded data obtained by performing compression or encryption of a digital signal is distributed to a receiver via a recording medium or a communication path, information such as a table of contents and a sample is separately attached. Without distributing the same information to multiple recipients at the same time, the recipients can selectively decrypt, and the sender can selectively specify the recipients for decryption Can be permitted. further,
Since there is no need to select and encrypt information for each recipient and distribute it, even if the number of recipients increases, a huge amount of work is not required for distribution.

Further, it is possible to distribute information having different qualities to each receiver only with the same data. Therefore, since it is not necessary to distribute the encrypted information for each quality, the amount of information to be distributed can be reduced, and the storage capacity of the encoded data recording medium can be more effectively used than the conventional one. Thus, in data transmission, the line utilization efficiency can be improved as compared with the conventional one.

[Brief description of the drawings]

FIG. 1 is a block circuit diagram showing a schematic configuration of a specific example of a digital signal encoding device as one embodiment of the present invention.

FIG. 2 is a block circuit diagram showing a schematic configuration of a specific example of a compressed data recording and / or reproducing device as a digital signal processing device using a digital signal encoding device according to an embodiment of the present invention.

FIG. 3 is a diagram illustrating a structure of an orthogonal transform block at the time of bit compression.

FIG. 4 is a block circuit diagram illustrating a configuration example of a circuit that determines an orthogonal transform block size.

FIG. 5 is a diagram illustrating a relationship between a change in temporal length of orthogonally adjacent orthogonal transform blocks and a window shape used at the time of orthogonal transform.

FIG. 6 is a diagram illustrating a specific example of a window shape used at the time of orthogonal transformation.

FIG. 7 is a block circuit diagram illustrating an example of a bit allocation calculation circuit using a convolution operation for implementing a bit allocation operation function.

FIG. 8 is a diagram illustrating spectra of each critical band and a band divided in consideration of block floating.

FIG. 9 is a diagram showing a masking spectrum.

FIG. 10 is a diagram in which a minimum audible curve and a masking spectrum are combined.

FIG. 11 is a block circuit diagram illustrating an example of an encryption circuit that performs 16-stage F function processing for implementing encryption.

FIG. 12 is a block circuit diagram showing specific processing contents of an F function used when implementing encryption.

FIG. 13 is a block circuit diagram illustrating an example of an encryption key control circuit that generates and controls an encryption key used when implementing encryption.

FIG. 14 is a diagram illustrating an example of a bit stream of encrypted and highly efficient encoded data according to the present embodiment.

FIG. 15 is a block circuit diagram showing a specific example of an embodiment of a digital signal decoding device corresponding to the digital signal encoding device shown in FIG. 2;

FIG. 16 is a block circuit diagram illustrating an example of an encryption / decryption circuit that performs 16-stage F-function processing for implementing encryption / decryption.

FIG. 17 is a block circuit diagram illustrating an example of an encryption key control circuit that generates and controls an encryption / decryption key used when implementing encryption / decryption.

FIG. 18 is a block circuit diagram showing a specific example of a digital signal encoding device according to another embodiment different from the embodiment of FIG. 1;

FIG. 19 is a block circuit diagram showing a specific example of an embodiment of a digital signal decoding device corresponding to the digital signal encoding device shown in FIG.

FIG. 20 is a flowchart illustrating a procedure of a decoding process of the digital signal decoding device according to the embodiment of the present invention.

[Explanation of symbols]

Reference Signs List 1 magneto-optical disk, 53 optical head, 54 magnetic head, 56 servo control circuit, 57 system controller, 61, 75 LPF, 6, A / D converter, 63 ATC encoder, 64, 72 memory, 65 encoder, 66 magnetic head Drive circuit,
71 decoder, 73 ATC decoder, 74
D / A converter, 101, 102 band synthesis filter (IQMF), 103, 104, 105 inverse orthogonal transform circuit (IMDCT), 106, 107, 108 adaptive bit allocation decoding circuit, 109-114 encryption / decryption circuit, 115 encryption Key control circuit, 116 encryption key table,
201, 202 band division filter, 203, 20
4,205 orthogonal transform circuit (MDCT), 206,2
07,208 block determination circuit, 209 bit allocation calculation circuit, 210, 211, 212 adaptive bit allocation coding circuit, 219, 220, 221 encryption circuit,
222 encryption key control circuit, 223, 224, 225
Encryption circuit, 302 initial value transposition circuit, 303-
318 F function circuit, 319 to 334 exclusive OR circuit, 335 final value transposition circuit, 337 key schedule unit, 404, 405, 406 power calculation circuit, 407 memory, 408 change extraction circuit,
409 power comparison circuit, 410 block size 1
Next decision circuit, 411 Block size correction circuit, 4
12, 413, 414 delay group, 415 window shape determination circuit, 503 enlargement transposition circuit, 504-5
11 Exclusive OR circuit, 512-519 S-BO
X circuit, 520 transposition circuit, 602, 603, 604
Encryption key generation circuit, 605 empty encryption key generation circuit, 6
06 encryption key control circuit, 607 to 618 switch circuit, 702 energy calculator per band, 703 convolution filter, 704 adder, 705 function generator, 706,708 subtractor, 707 synthesizer,
709 delay circuit, 710 allowable noise corrector, 71
2 Minimum audible curve generator, 713 Correction information output device, 802 Initial value transposition circuit, 803-818F
Function circuit, 819-834 Exclusive OR circuit, 8
35 final value transposition circuit, 837 key schedule part,
902, 903, 904 encryption key generation circuit, 905
Empty encryption key generation circuit, 906 Encryption key control circuit, 9
07-918 switch circuit

Claims (25)

[Claims] 1. A digital signal encoding apparatus for encoding an input digital signal, comprising: block distribution means for distributing the input digital signal into small blocks subdivided in at least one of time and frequency; and spectrum data on a frequency axis. , A bit allocation calculating means for calculating the number of allocated bits for compression for each of the subdivided small blocks, and encoding according to the number of bits allocated by the bit allocation calculating means. Allocated bit encoding means, encryption means for encrypting at least a part of the subdivided small blocks, and encryption key control for generating an encryption key for controlling encryption by the encryption means Means for digital signal encoding. 2. The encryption device according to claim 1, wherein said encryption means is capable of selecting an encryption range, and said encryption key control means selectively controls an encryption range in said encryption means. Digital signal encoding device. 3. The small block is obtained by subdividing the input digital signal with respect to time and frequency.
The spectrum data output means has orthogonal transform means for obtaining spectrum data on a frequency axis for each of the small blocks, and the bit allocation means obtains an allowable noise spectrum from the spectrum data, and obtains the obtained allowable noise spectrum. 2. The digital signal encoding apparatus according to claim 1, wherein the digital signal is distributed into small blocks subdivided with respect to time and frequency, and bit allocation for compression is performed. 4. The encryption means encrypts independently for each small block subdivided in frequency,
2. The digital signal encoding apparatus according to claim 1, wherein said encryption key control means generates an encryption key for independently encrypting each small block divided into frequencies. 5. The encryption means independently encrypts each small block divided in time, and the encryption key control means independently encrypts each small block divided in time. 2. The digital signal encoding apparatus according to claim 1, wherein the digital signal encoding apparatus generates an encryption key for encoding. 6. The encrypting means comprises serially connected means for multiplexly encrypting small blocks subdivided with respect to frequency, and the encryption key control means comprises subdivided with respect to frequency. 2. A digital signal according to claim 1, wherein an encryption key for encrypting the small blocks in a multiplex manner is generated, and said encrypting means encrypts said small blocks in a single and / or multiplex manner. Encoding device. 7. The encryption means comprises serially connected means for multiplexly encrypting small blocks subdivided with respect to time, and the encryption key control means comprises:
An encryption key for encrypting multiple small blocks subdivided with respect to time is generated, and said encryption means encrypts said small blocks individually and / or multiple. 2. The digital signal encoding device according to 1. 8. The block distributing means changes the time length of a processing block for information compression in accordance with an input signal, and changes the input signal of the processing block and the input signal of another processing block. 2. A digital signal code according to claim 1, further comprising a processing block length determining means for determining a time length of the processing block based on change and / or power, energy or peak information. Device. 9. The block distributing means changes a temporal length of a processing block for information compression in accordance with an input signal, and calculates a change in an input signal of the processing block and a temporal maximum of the processing block. 2. The digital signal according to claim 1, further comprising processing block length determining means for determining a time length of the processing block based on change information of the input signal obtained by the input signal having a long time width. Encoding device. 10. The block distribution means changes the time length of a processing block for information compression in accordance with an input signal, and changes the input signal of the processing block and the input signal of an external processing block. A function of determining the time length of the corresponding processing block based on the change and / or power, or energy or peak information, and making the time length of the processing block variable in accordance with the input signal; A processing block length having a function of determining the length of the processing block based on a change in the input signal of the processing block and change information of the input signal obtained by an input signal having a time width longer than the maximum of the processing block in time. 2. The digital signal encoding apparatus according to claim 1, further comprising a determination unit. 11. The processing block length determination means may fix a ratio involved in determining an element for determining a time length of a processing block, or may use a ratio adapted to an input signal and / or a predetermined ratio together or independently. 11. The digital signal encoding apparatus according to claim 10, wherein the digital signal encoding apparatus is used for: 12. The digital signal according to claim 1, wherein the input signal is an audio signal, and the higher the frequency, the wider the frequency width of a block for controlling the generation of at least most of the quantization noise. Signal encoding device. 13. The spectrum data output means includes: an orthogonal transform means that uses an orthogonal transform to divide a time axis signal into a plurality of bands on a frequency axis; 2. The digital signal encoding apparatus according to claim 1, further comprising an orthogonal transform size and window function shape changing means for changing a shape of a window function to be used. 14. When dividing the time axis signal into a plurality of bands on the frequency axis, first, the signal is divided into a plurality of bands,
14. The digital signal encoding apparatus according to claim 13, wherein a block including a plurality of samples is formed for each of the divided bands, and coefficient data is obtained by performing orthogonal transformation for each block of each band. 15. A digital signal encoding method for encoding an input digital signal, comprising: distributing the input digital signal into small blocks subdivided in at least one of time and frequency; and obtaining an allowable noise spectrum from the spectrum data. A step of distributing the obtained allowable noise spectrum into small blocks subdivided with respect to time and frequency, and performing a bit allocation step of performing bit allocation for compression; and a step of performing encoding according to the allocated number of bits, Encrypting at least a part of the small blocks subdivided with respect to at least one of time and frequency; and generating an encryption key for encrypting the at least some of the small blocks. Digital signal encoding method. 16. The digital signal encoding method according to claim 15, wherein said encryption is performed independently for each of small blocks divided into at least one of time and frequency. 17. The digital signal encoding method according to claim 15, wherein said encryption multiplexes small blocks subdivided in at least one of time and frequency. 18. A digital signal decoding apparatus for decoding an encoded digital signal, wherein the encoded digital signal is converted into a small block obtained by subdividing an original input digital signal in at least one of time and frequency. Distribution, obtaining an allowable noise spectrum from the spectrum data, distributing the obtained allowable noise spectrum into small blocks subdivided in time and frequency, performing bit allocation for compression, and encoding according to the allocated number of bits. Is obtained by selectively encrypting at least a part of the small block subdivided for at least one of time and frequency, and the small block of the encoded digital signal is obtained. Encryption / decryption means for decrypting at least a part of the encryption, and information for the encryption / decryption And encryption key information, and encryption key control means for controlling encryption / decryption by the encryption / decryption means; decryption means for performing decryption for each small block as reverse processing of the encoding; and for each small block. And a synthesizing means for synthesizing the decoded signal. 19. In the encryption, encryption is performed independently for each small block subdivided in at least one of time and frequency, and the encryption / decryption unit performs encryption / decryption independently for each small block. 19. The digital signal decoding apparatus according to claim 18, wherein the decoding is performed. 20. In the encryption, small blocks subdivided in at least one of time and frequency are encrypted in a multiplex manner, and the encryption / decryption means decrypts the encryption in which the small blocks are multiplexed. 19. A method according to claim 18, comprising means connected in series.
A digital signal decoding device according to claim 1. 21. A digital signal decoding method for decoding an encoded digital signal, wherein the encoded digital signal is converted into small blocks obtained by subdividing an original input digital signal with respect to at least one of time and frequency. Distribution, obtaining an allowable noise spectrum from the spectrum data, distributing the obtained allowable noise spectrum into small blocks subdivided in time and frequency, performing bit allocation for compression, and encoding according to the allocated number of bits. Is obtained by selectively encrypting at least a part of the small block subdivided for at least one of time and frequency, and the small block of the encoded digital signal is obtained. An encryption / decryption step of decrypting at least a part of the encryption, and information for the encryption / decryption. Controlling the encryption / decryption in the encryption / decryption step in accordance with the encryption key information; and performing the decoding for each small block as a reverse process of the encoding; and decoding for each small block. Synthesizing a signal. 22. A signal recording medium on which an encoded digital signal is recorded, wherein the encoded digital signal is divided into small blocks obtained by subdividing an original input digital signal in at least one of time and frequency. Then, an allowable noise spectrum is obtained from the spectrum data, the obtained allowable noise spectrum is distributed to small blocks subdivided with respect to time and frequency, bits are allocated for compression, and encoding is performed according to the allocated number of bits. A signal recording medium obtained by selectively encrypting at least a part of small blocks obtained by subdividing at least one of time and frequency. 23. A digital signal transmission method for encoding and transmitting an input digital signal, comprising the steps of: distributing the input digital signal into small blocks subdivided in at least one of time and frequency; A step of determining, distributing the obtained allowable noise spectrum into small blocks subdivided with respect to time and frequency, and performing a bit allocation step of performing bit allocation for compression; and a step of performing encoding according to the allocated number of bits. Encrypting at least a part of the small blocks subdivided in at least one of time and frequency; and generating an encryption key for encrypting the at least some of the small blocks. Transmitting a digital signal, Signal encoding method. 24. The digital signal transmission method according to claim 23, wherein the encryption is performed independently for each of small blocks divided into at least one of time and frequency. 25. The digital signal transmission method according to claim 23, wherein in the encryption, a small block segmented in at least one of time and frequency is multiplexed and encrypted.