JP2003263195A - Method and device for reproducing signal, method and device for recording signal, and method and device for generating code string - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To remove dangerousness of illegally improving the quality of music contents or the like while attaining trial listening of the contents, to make it possible to reproduce contents of high quality by acquiring data of comparatively small volume and to realize the reproduction of the contents by hardware at a lower cost. <P>SOLUTION: In the case of preparing trial listening data including dummy data, a false random number R is generated in a step S54, a residue r (r=R%128) obtained by dividing the false random number R by 128 is obtained in a step S55, the residue r is encoded and written in high quality data in a step S56, and the trial listening data are converted into dummy data from the r-the bit of a band limit area of the trial listening data. Since trial listening data in which the head position of the dummy data is changed in each frame can be obtained, the strength of safeness can be held at a high level. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a signal reproducing method and apparatus, a signal recording method and apparatus, and a code string generating method and apparatus, and for example, encodes a signal so that trial viewing can be performed. As a result, if the trial viewer decides to purchase, a signal reproducing method and apparatus, a signal recording method and apparatus, and a code string that add data of a small amount of information and enable high quality reproduction and recording. The present invention relates to a generation method and device.

[0002]

2. Description of the Related Art For example, a content (software) that encrypts a signal such as sound and broadcasts it, or records it on a recording medium, and permits only a person who purchases a decryption key to view it. Distribution methods are known.

As an encryption method, for example, an initial value of a random number sequence is given as a key signal to a bit string of a PCM audio signal, and an exclusive logic of the generated 0/1 random number sequence and the PCM bit string is used. A method of transmitting a summed bit string or recording the bit string on a recording medium is known. By using this method, only the person who obtains the key signal can correctly reproduce the acoustic signal, and the person who does not obtain the key signal can reproduce only the noise. Of course, the encryption method is so-called DES
It is also possible to use a more complicated method such as (Data Encryption Standard). For the DES standard, refer to the document "Federal Information Processing Sta.
ndards Publication 46, Specifications for the DATA
The contents are disclosed in "ENCRYPTION STANDARD, 1977, January 15".

On the other hand, a method of compressing an audio signal for broadcasting or recording it on a recording medium has become widespread, and a recording medium such as a magneto-optical disk capable of recording coded audio or voice signals has been developed. Widely used.

There are various techniques for high-efficiency coding of signals such as audio or voice. For example, non-blocking in which audio signals on the time axis are not divided into blocks but divided into a plurality of frequency bands for coding. Frequency band division scheme, which is band division coding (sub-band coding:
SBC) or a block frequency band division method that transforms a signal on the time axis into a signal on the frequency axis (spectral conversion) and divides into a plurality of frequency bands, and encodes each band, so-called conversion encoding. Can be mentioned. Further, a method of high efficiency coding in which the above band division coding and transform coding are combined is also considered, and in this case, for example, after performing band division by the band division coding, A signal for each band is spectrum-converted into a signal on the frequency axis, and each spectrum-converted band is encoded.

Here, as the above-mentioned filter, there is, for example, a QMF filter, and this QMF filter is described in the document “1976, RECrochiere, Digital coding of s”.
peechin subbands, Bell Syst. Tech. J. Vol.55, No.
8, 1976 ”. In addition, the document “ICASSP 83,
BOSTON, Polyphase Quadrature filters-A new subban
d coding technique, Joseph H. Rothweiler, "describes a technique for equal-bandwidth filter partitioning.

Further, as the above-mentioned spectrum conversion,
For example, input audio signal to a predetermined unit time (frame)
There is a spectrum conversion in which a time axis is converted into a frequency axis by performing block formation with each block and performing discrete Fourier transform (DFT), discrete cosine transform (DCT), modified DCT transform (MDCT), and the like for each block. MDC
For T, refer to the document “ICASSP, 1987, Subband / Transfor
m Coding Using FilterBank Designs Based on Time Do
main Aliasing Cancellation, JPPrincen, ABBradl
ey, Univ. of Surrey Royal Melbourne Inst. of Tec
h. ”.

When the above-mentioned DFT or DCT is used as a method of converting a waveform signal into a spectrum, M independent real number data are obtained by performing conversion with a time block consisting of M samples. In order to reduce the connection distortion between time blocks, it is usually necessary to use M and
Since the samples are overlapped one by one, on the average, in the DFT or DCT, M real number data are quantized and coded for (M-M1) samples.

On the other hand, when the above-mentioned MDCT is used as a method for converting into a spectrum, from 2M samples which are overlapped by M times with the time on both sides,
Since M independent real number data are obtained, on average, M
In DCT, M pieces of real number data are quantized and encoded for M pieces of samples. In the decoding device, the waveform signal can be reconstructed by adding the waveform elements obtained by performing the inverse transformation in each block from the code obtained by using the MDCT while interfering with each other. .

Generally, by lengthening the time block for conversion, the frequency resolution of the spectrum is increased,
Energy is concentrated on specific spectral components. Therefore, it is possible to perform the DFT and DCT
It is possible to perform encoding more efficiently than when using. Further, it is possible to reduce the block-to-block distortion of the waveform signal by allowing adjacent blocks to have a sufficiently long overlap.

As described above, by quantizing the signal divided for each band by the filter and the spectrum conversion,
It is possible to control the band in which the quantization noise is generated, and it is possible to perform auditory and more efficient encoding by utilizing properties such as the masking effect. Further, if the normalization is performed for each band, for example, with the maximum value of the absolute value of the signal component in that band before the quantization is performed here, more efficient encoding can be performed.

As a frequency division width for quantizing each frequency component divided into frequency bands, for example, band division is performed in consideration of human auditory characteristics. That is, an audio signal may be divided into a plurality of bands (for example, 25 bands) with a bandwidth that increases in a higher frequency range generally called a critical band.
Also, when encoding the data for each band at this time,
Encoding is performed by predetermined bit allocation for each band or adaptive bit allocation (bit allocation) for each band. For example, when the coefficient data obtained by the MDCT processing is encoded by the bit allocation, adaptive allocation bits are assigned to the MDCT coefficient data for each band obtained by the MDCT processing for each block. The encoding will be performed by numbers.

The following two methods are known as such bit allocation methods. That is, first, the document “Adaptive
Transform Coding of Speech Signals, R. Zelinski a
nd P. Noll, IEEE Transactions of Acoustics, Speec
h, and Signal Processing, vol.ASSP-25, No.4, Augus
In "1977," bit allocation is performed based on the signal size of each band. In this method, the quantization noise spectrum becomes flat and the noise energy becomes the minimum, but the actual noise feeling is not optimal because the masking effect is not used auditorily. In addition, the document “ICASSP 1980,
The criticalband coder-digital encoding of th
e perceptual requirements of the auditory system,
“MAKransner MIT” describes a method of performing fixed bit allocation by using auditory masking to obtain the required signal-to-noise ratio for each band. However, in this method, even when the characteristic is measured with a sine wave input, the characteristic value is not so good because the bit allocation is fixed.

In order to solve these problems, all bits that can be used for bit allocation have a fixed bit allocation pattern predetermined for each small block and a bit allocation depending on the signal size of each block. A high-efficiency coding apparatus has been proposed which is used in a divided manner, and the division ratio depends on a signal related to an input signal, and the smoother the spectrum of the signal, the larger the division ratio into the fixed bit allocation pattern. ing.

According to this method, when energy is concentrated on a specific spectrum such as a sine wave input, a large number of bits are allocated to a block including the spectrum, thereby significantly improving the overall signal-to-noise characteristic. can do. In general, human hearing is extremely sensitive to a signal having a steep spectrum component. Therefore, improving the signal-to-noise characteristic by using such a method does not only improve the numerical value in measurement. Not
It is effective for improving the sound quality in terms of hearing.

Many other methods have been proposed for the bit allocation method. Further, if the model relating to hearing is further refined and the performance of the coding apparatus is improved, a more efficient coding can be achieved auditorily. It will be possible. In these methods, it is general that a real number bit allocation reference value that realizes the signal-to-noise characteristics obtained by calculation as faithfully as possible is obtained, and an integer value approximating it is used as the number of assigned bits. .

In addition, in the specification and drawings of Japanese Patent Application No. 5-152865 or WO94 / 286633 previously proposed by the inventors of the present invention, a tonal component which is particularly important in terms of hearing from the spectrum signal, that is, a specific component is specified. A method has been proposed in which a signal component in which energy is concentrated around the frequency is separated and encoded separately from other spectral components, which causes almost no deterioration of the audio signal in terms of hearing. It is possible to efficiently encode with a very high compression rate.

In constructing an actual code string, first, the quantization accuracy information and the normalization coefficient information are encoded with a predetermined number of bits for each band in which normalization and quantization are performed.
Next, the normalized and quantized spectrum signal may be encoded. Also, ISO / IEC 11172-3: 1993 (E), 1993
Describes a high-efficiency coding method in which the number of bits representing the quantization accuracy information is set to be different depending on the band. It is standardized.

There is also known a method of determining the quantization accuracy information from the normalization coefficient information in the decoding device instead of directly encoding the quantization accuracy information, but in this method, at the time when the standard is set. Since the relationship between the normalization coefficient information and the quantization accuracy information is determined by, it becomes impossible to introduce the quantization accuracy control based on a more advanced auditory model in the future. In addition, when the compression rate to be realized has a range, it becomes necessary to determine the relationship between the normalization coefficient information and the quantization accuracy information for each compression rate.

The quantized spectral signal is, for example,
Reference `` DA Huffman: A Method for Construction of Mi
nimum Redundancy Codes, Proc.IRE, 40, p.1098 (1
952) ”, a more efficient encoding method is known by encoding using a variable length code.

[0021]

By the way, only for a person who purchases a key by enciphering a signal such as a sound coded by the above-mentioned method and broadcasting it or recording it on a recording medium. A method of distributing software contents, which permits the viewing, is known. As an encryption method,
For example, an initial value of a random number sequence is given as a key signal to a bit string of an acoustic signal of PCM (Pulse Code Moduration) or to a bit string of an encoded signal,
There is known a method of transmitting a bit string obtained by an exclusive OR of the generated 0/1 random number sequence and the bit string or recording the bit string on a recording medium. By using this method,
Only the person who obtains the key signal can reproduce the sound signal correctly, and the person who does not obtain the key signal can reproduce only the noise.

However, in these scramble methods, when there is no key or when it is played back by a normal playback means, it causes noise when played back, and the contents of the software cannot be grasped. . Therefore, for example, by distributing a disc in which music is recorded with a relatively low sound quality, a person who auditioned it can purchase a key only for what he / she likes, and reproduce it with a high sound quality, or It could not be used for the purpose of making it possible to purchase a new disc recorded with high sound quality after listening to the software.

Further, conventionally, when encrypting a signal which has been subjected to high efficiency coding, it has been difficult to prevent the compression efficiency from being lowered while giving a code string which is meaningful to ordinary reproducing means. . That is, as described above, when scrambling is applied to a code string formed by applying a high efficiency code, not only noise is generated even if the code string is reproduced, but the code string generated by scrambling is If it does not comply with the standard of high efficiency code, the reproducing means may not operate at all. On the other hand, when the PCM signal is scrambled and then high-efficiency coded, the amount of information is reduced by utilizing, for example, the property of hearing.
When the high efficiency coding is released, the PCM
Since it is not possible to reproduce a signal that is scrambled, it becomes difficult to descramble correctly. For this reason, it was necessary to select a compression method that can descrambling correctly even if the efficiency is reduced.

On the other hand, according to the technique disclosed in Japanese Patent Laid-Open No. 10-135944 previously proposed by the present inventors, for example, among music signals converted into spectrum signals and encoded, An audio encoding method is disclosed in which only the high frequency side is encrypted and a narrow band signal can be auditioned without a key. That is, in this method, for example, the high-frequency side is encrypted and the high-frequency side bit allocation information and the like are replaced with dummy data, and the true high-frequency side bit allocation information is recorded at a position ignored by a normal decoder. is doing. If this method is adopted, for example,
As a result of the audition, it is possible to enjoy only the music that you like with high sound quality.

By the way, the above-mentioned Japanese Unexamined Patent Publication No. 10-135944.
In the technology described in the publication, the security depends only on the encryption, so if the code is decrypted, it is possible to listen to high-quality music without collecting the fee. There is a risk of being able to do it.

The present invention has been proposed in view of the above-mentioned circumstances, and allows the trial viewing and listening, but eliminates the risk that the code is decrypted without encrypting a part of the signal. In addition, it is possible to perform high-quality signal reproduction only by obtaining a relatively small amount of additional data in the signal supplied for trial viewing, and it is difficult to know the information about this additional data. An object of the present invention is to provide a signal reproducing method and device, a signal recording method and device, and a code string generating method and device that can keep the safety strength of trial viewing data high.

[0027]

According to the present invention, in each frame of a code string obtained by coding a signal on a frame-by-frame basis, a part of the code string is replaced with dummy data to obtain trial viewing data. The position of the dummy data is variable, and the position information is included in the quality-improved data.

The applicant of the present invention first distributed data (trial viewing data) in which a part of the code string was replaced with dummy data so that trial viewing could be performed, and relatively low quality reproduction with a narrow bandwidth was performed. If you like the content of the sound and images freely, and as a result, you like the content and the trial viewer decides to purchase it, you can receive the correct data (high quality data) to replace the dummy data and enjoy high quality playback. We are proposing such a technology. In this case, the music signal is converted into spectral coefficients for each block of a predetermined length, divided into tonal components and other components, and the tonal components are normalized and requantized for each tonal component. The components other than are normalized and requantized for each predetermined band, and when the spectrum signal obtained by requantization is encoded from the low frequency side using the variable length code, the tone-like component above the predetermined frequency And normalization coefficients of other components are replaced with dummy data, and among the spectral components coded in variable length, the low frequency side spectral components above the predetermined frequency are also replaced with dummy data. There is. As described above, by obtaining the additional data string for replacing the dummy data with respect to the trial data string including the dummy data and integrating the two, it is possible to reproduce a music signal having a wide band. In such a technique, as an important factor in maintaining the safety strength, the length of the variable-length coded spectrum component that replaces the spectrum component on the low frequency side above the predetermined frequency with dummy data Can be mentioned. That is, when the N-bit spectrum code string is replaced with dummy data,
Since there is a possibility of a combination of 2 to the Nth power of the code string, as N is increased, it is possible to increase the safety strength so as not to restore correct data from the trial viewing data. However, increasing the value of N leads to increasing the data amount of the quality-improved data, and lengthens the data download time required when the trial viewer decides to purchase the quality-improved data. Resulting in.

Therefore, in the present invention, the position at which the variable-length code string is replaced with dummy data is variable, and the position information is included in the quality-improved data.
Even if the value of N is relatively small, by increasing the number of combinations for estimating the quality-improved data from the trial-viewing data, the size of the quality-improved data can be made relatively small and the trial-viewing can be performed. It is designed to keep the safety strength of data high.

That is, in the signal reproducing method and apparatus according to the present invention, when reproducing a code string obtained by coding a signal in a predetermined unit (for example, a frame unit), a part of the code string becomes dummy data. The input first code string is input,
When a second code string for complementing the dummy data part is input, at least a part of the dummy data part in the first code string is complemented using the second code string ( (For example, rewriting) to decode the complemented (rewritten) code string or the first code string, and the position of the dummy data of the first code string is variable in the predetermined unit. Is characterized in that.

Further, in the signal recording method and apparatus according to the present invention, when a code string obtained by coding a signal in frame units is recorded on a recording medium, a part of the code string is used as dummy data. The first code string is input, and the second code string for complementing the dummy data portion is input,
With respect to the first code string, the dummy data portion is rewritten to the second code string.
The position of the dummy data in the code string of is changed.

Further, the code string generating method and apparatus according to the present invention generates a code string of a predetermined format by coding an input signal, and rewrites a part of the code string of the predetermined format into dummy data. A code string of No. 1 is generated, a part of the code string of the predetermined format corresponding to the position of the dummy data is extracted to generate a second code string, and the dummy code of the first code string is generated. It is characterized in that the position of data changes.

Here, in the above encoding, the input signal is spectrally converted, band-divided, and a code string of a predetermined format including quantization accuracy information, normalization coefficient information, and spectrum coefficient information for each band is obtained. The generated dummy data may be dummy data corresponding to at least a part of the spectral coefficient information. Further, the spectrum coefficient information is encoded by a variable length code, and the dummy data of the first code string is encoded by the original data when encoded by the variable length code. It can be mentioned that the length is less than the data.

In the present invention, as a predetermined format used for encoding an input signal, for example, at least a portion (eg, spectrum coefficient, pixel value, etc.) relating to content data on a code string and decoding of the code are performed. It is preferable to apply a format in which necessary coding parameters (for example, quantization accuracy information, normalization coefficient information, etc.) are multiplexed. In this case, for example, it is also possible to multiplex the meta information describing the attribute of the content, the copyright management information, the encryption information, or the like on the code string.

[0035]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First, prior to describing an embodiment of the present invention, an optical disk recording / reproducing apparatus as a general compressed data recording / reproducing apparatus for explaining the embodiment of the present invention will be described with reference to the drawings. While explaining.

FIG. 1 is a block diagram showing an example of an optical disk recording / reproducing apparatus. In the device shown in FIG. 1,
First, as the recording medium, the magneto-optical disk 1 which is rotationally driven by the spindle motor 51 is used. At the time of recording data on the magneto-optical disk 1, for example, so-called magnetic field modulation recording is performed by applying a modulation magnetic field according to the recording data with the magnetic head 54 in a state where the optical head 53 irradiates the laser beam, and the so-called magnetic field modulation recording is performed.
Data is recorded along the recording track of. During reproduction, the recording track of the magneto-optical disk 1 is moved to the optical head 5
With 3, laser light is traced 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 a polarization beam splitter, an optical component such as a cylindrical lens, and a photodetector having a light receiving portion of a predetermined pattern. The optical head 53 is provided at a position facing the magnetic head 54 through the magneto-optical disk 1. When recording data on the magneto-optical disk 1, the magnetic head 54 is driven by a head driving circuit 66 of a recording system described later to apply a modulation magnetic field according to the recording data, and at the same time, the optical head 53 is used for the purpose of the magneto-optical disk 1. By irradiating the track with laser light, thermomagnetic recording is performed by the magnetic field modulation method. Further, the optical head 53 detects the reflected light of the laser light 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 and reproduces it. Generate a signal.

The output of the optical head 53 is supplied to the 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 them to the servo control circuit 56, and binarizes the reproduction signal to reproduce the reproduction system decoder 7 described later.
Supply to 1.

The servo control circuit 56 is composed of, for example, a focus servo control circuit, a tracking servo control circuit, a spindle motor servo control circuit, a sled servo control circuit, and the like. The focus servo control circuit controls the focus of the optical system of the optical head 53 so that the focus error signal becomes zero. Further, the tracking servo control circuit controls the tracking 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). Further, the sled servo control circuit moves the optical head 53 and the magnetic head 54 to the target track position of the magneto-optical disk 1 designated by the system controller 57. The servo control circuit 56 that performs such various control operations sends information indicating the operating state of each unit controlled by the servo control circuit 56 to the system controller 57.

A key input operation section 58 and a display section 59 are connected to the system controller 57. The system controller 57 controls the recording system and the reproduction system according to the operation input information by the operation input information from the key input operation unit 58. Further, the system controller 57 records the above-mentioned recording traced by the optical head 53 and the magnetic head 54 based on the address information in sector units reproduced from the recording track of the magneto-optical disc 1 by the header time, the Q data of the subcode and the like. Manages the recording and playback positions on the track. Further, the system controller 57 controls to display the reproduction time on the display unit 59 based on the data compression rate of the main compression data recording / reproducing apparatus and the reproduction position information on the recording track.

The reproduction time display is the reciprocal of the data compression rate (absolute time information) with respect to the sector unit address information (absolute time information) reproduced from the recording track of the magneto-optical disk 1 by so-called header time or 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 59. Even at the time of recording, when absolute time information is recorded (pre-formatted) in advance on a recording track of a magneto-optical disk or the like, the pre-formatted absolute time information is read to determine the data compression rate. It is also possible to display the current position at the actual recording time by multiplying by the reciprocal.

Next, in the recording system of the optical disk recording / reproducing apparatus shown in FIG. 1, the analog audio input signal A _IN from the input terminal 60 is supplied to the A / D converter 62 via the low-pass filter 61, and this A / D converter 62
Quantizes the analog audio input signal A _IN . The digital audio signal obtained from the A / D converter 62 is ATC (Adaptive Transform Coding: Adaptive Transform).
Coding) It is supplied to the encoder 63. The digital audio input signal _{D I N} from the input terminal 67 is supplied to the ATC encoder 63 via a digital input interface circuit 68. The ATC encoder 63 performs bit compression (data compression) processing according to a predetermined data compression rate on digital audio PCM data of a predetermined transfer rate obtained by quantizing the input signal A _IN by the A / D converter 62. And the ATC encoder 63
The compressed data (ATC data) output from is supplied to the memory (RAM) 64. For example, the data compression rate is 1
In the case of / 8, the data transfer rate here is ⅛ (9. 9) of the data transfer rate (75 sectors / second) of the so-called CD-DA format format which is a standard digital audio CD format. 375
Sector / second).

Next, in the memory (RAM) 64, the writing and reading of data are controlled by the system controller 57 and the AT supplied from the ATC encoder 63.
It is used as a buffer memory for temporarily storing C data and recording it on the disk as needed. That is, for example, when the data compression rate is ⅛, the compressed audio data supplied from the ATC encoder 63 has a standard CD transfer rate.
-DA format data transfer rate (75 sectors /
1/8 of the second), that is, 9.375 sectors / second, and this compressed data is continuously written in the memory 64. As for the compressed data (ATC data), it is sufficient to record one sector for every eight sectors as described above.
Since it is practically impossible to record every 8 sectors like this, continuous recording as described later is performed.

In this recording, a cluster consisting of a plurality of predetermined sectors (for example, 32 sectors + several sectors) is used as a recording unit for the same data transfer rate as the standard CD-DA format (75 sectors / sec. ) Is done in a burst. That is, in the memory 64, 9.375 (= 75/8) sectors / corresponding to the above bit compression rate
ATC audio data having a data compression rate of ⅛ continuously written at a low transfer rate of 2 seconds is burst-read as recording data at the transfer rate of 75 sectors / second. For this read and recorded data, the overall data transfer rate including the recording pause period is 9.3 above.
Although the speed is as low as 75 sectors / second, the instantaneous data transfer speed within the time of the recording operation performed in a burst is the standard 75 sectors / second. Therefore,
When the disc rotation speed is the same as the standard CD-DA format (constant linear velocity), the same recording density and recording pattern as those of the CD-DA format are recorded.

The ATC audio data, that is, the recording data, which is burst-read from the memory 64 at the (instantaneous) transfer rate of 75 sectors / second is recorded by the encoder 65.
Is supplied to. Here, from the memory 64 to the encoder 65
In the data string supplied to the above, the unit of continuous recording in one recording is a cluster composed of a plurality of sectors (for example, 32 sectors) and several sectors for cluster connection arranged in the front and rear positions of the cluster. This cluster connection sector is set longer than the interleave length in the encoder 65 so that the data of other clusters will not be affected even if interleaved.

The encoder 65 uses the recording data supplied in burst from the memory 64 as described above.
Encoding processing (parity addition and interleave processing) for error correction, EFM encoding processing, and the like are performed. The recording data encoded 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 as to apply the modulation magnetic field according to the recording data to the magneto-optical disk 1.

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

Next, the reproducing system of the optical disk recording / reproducing apparatus shown in FIG. 1 will be described. This reproducing system is for reproducing the recording data continuously recorded on the recording track of the magneto-optical disk 1 by the above-mentioned recording system, and the recording track of the magneto-optical disk 1 is laser-lighted by the optical head 53. The decoder 71 is provided with which the reproduction output obtained by tracing at (1) is binarized by the RF circuit 55 and supplied. In this case, not only the magneto-optical disk but also the so-called CD (Compact Disk: Compact Di
It is also possible to read the same read-only optical disc as sc) or a so-called CD-R type optical disc.

The decoder 71 corresponds to the encoder 65 in the above-mentioned recording system, and performs the above-mentioned decoding processing for error correction, EFM decoding processing, etc. on the reproduction output binarized by the RF circuit 55. Is performed to reproduce the above-mentioned ATC audio data having a data compression rate of ⅛ at a transfer rate of 75 sectors / second, which is faster than the normal transfer rate. The reproduction data obtained by the decoder 71 is supplied to the memory (RAM) 72.

In the memory (RAM) 72, writing and reading of data are controlled by the system controller 57, and reproduced data supplied from the decoder 71 at a transfer rate of 75 sectors / sec burst at the transfer rate of 75 sectors / sec. Will be written. Also, this memory 72 is
The reproduction data written in bursts at the transfer rate of 75 sectors / second is continuously read at the transfer rate of 9.375 sectors / second corresponding to the data compression rate of 1/8.

The system controller 57 writes the reproduced data into the memory 72 at a transfer rate of 75 sectors / second, and continuously reads the reproduced data from the memory 72 at the transfer rate of 9.375 sectors / second. Take control. Further, the system controller 57 performs the above-mentioned memory control on the memory 72, and continuously reproduces the above-mentioned reproduction data written in a burst in the memory 72 from the recording track of the magneto-optical disk 1 by this memory control. Controls the playback position. The control of the reproduction position manages the reproduction position of the reproduction data continuously read from the memory 72 by the system controller 57 and outputs a control signal for designating the reproduction position on the recording track of the magneto-optical disc 1 or the optical disc 1. This is performed by supplying the servo control circuit 56.

A obtained as reproduced data continuously read from the memory 72 at a transfer rate of 9.375 sectors / sec.
The TC audio data is supplied to the ATC decoder 73. The ATC decoder 73 is the ATC of the recording system.
It corresponds to the encoder 63 and reproduces 16-bit digital audio data by, for example, expanding the ATC data 8 times (bit expanding). This ATC
The digital audio data from the decoder 73 is D /
It is supplied to the A converter 74.

The D / A converter 74 is the ATC decoder 73.
Analog audio output signal A _OUT by converting digital audio data supplied from
To form. The analog audio signal A _OUT obtained by the D / A converter 74 is a low-pass filter 75.
Is output from the output terminal 76 via.

Next, the high-efficiency compression coding of the signal will be described in detail. That is, with reference to FIG. 2 and subsequent figures, for a technique for highly efficient encoding of an input digital signal such as an audio PCM signal using band division encoding (SBC), adaptive transform encoding (ATC) and adaptive bit allocation techniques. While explaining.

FIG. 2 is a block diagram showing a concrete example of an acoustic waveform signal coding apparatus used for explaining the embodiment of the present invention. In this example, the input signal waveform 101 is converted by the conversion means 1101 into a signal 102 of a signal frequency component.
After being converted into, the signal component encoding means 1102 encodes each component, and the code string generation means 1103 generates the code string 104.

FIG. 3 shows a concrete example of the transforming means 1101 of FIG. 2, in which the signals divided into two bands by the band splitting filter are spectral signal components by the forward spectrum transforming means 1211, 1212 such as MDCT in each band. 221 and 222. Signal 2 in FIG.
01 corresponds to the signal 101 in FIG. 2 and each signal 22 in FIG.
1, 222 correspond to the signal 102 in FIG. In the conversion means of FIG. 3, the bandwidth of the signals 211 and 212 is the signal 201.
Of the signal 201 and is decimated to 1/2 of the signal 201. There are various conceivable conversion means other than this specific example. For example, the input signal may be directly converted into a spectrum signal by MDCT, or DFT (discrete Fourier transform) or DCT (discrete cosine transform) instead of MDCT. May be converted by Although it is possible to divide a signal into band components by a so-called band division filter, it is convenient to adopt a method of converting the signals into frequency components by the above-mentioned spectrum conversion in which a large number of frequency components are obtained with a relatively small amount of calculation.

FIG. 4 shows the signal component coding means 110 of FIG.
2 shows a specific example, and the input signal 301 is the normalization means 13
After being normalized for each predetermined band by 01 (signal 302), the quantizing means 130 is based on the quantizing accuracy information 303 calculated by the quantizing accuracy determining means 1302.
Quantized by 3 and extracted as a signal 304. The signal 301 in FIG. 4 corresponds to the signal 102 in FIG. 2 and the signal 304 in FIG. 4 corresponds to the signal 103 in FIG. 2, but here, the signal 304 includes the quantized signal component and the normalization coefficient. Information and quantization accuracy information are also included.

FIG. 5 is a block diagram showing a concrete example of a decoding device for outputting an acoustic signal from the code string generated by the coding device shown in FIG. In this specific example, the code sequence decomposition means 1401 extracts the code 402 of each signal component from the code sequence 401, and the signal component decoding means 1402 restores each signal component 403 from the code 402 and then the inverse transform means 1403. The acoustic waveform signal 404 is output by.

FIG. 6 shows a specific example of the inverse transforming means 1403 of FIG. 5, which corresponds to the specific example of the transforming means of FIG. 3, and the respective bands obtained by the inverse spectrum transforming means 1501 and 1502. The signals 511 and 512 are synthesized by the band synthesis filter 1511. The signals 501 and 502 in FIG. 6 correspond to the signal 403 in FIG. 5, and the signal 521 in FIG. 6 corresponds to the signal 404 in FIG.

FIG. 7 shows the signal component decoding means 1402 of FIG.
7, the signal 551 of FIG. 7 corresponds to the signal 402 of FIG. 5, and the signal 553 of FIG. 7 corresponds to the signal 403 of FIG. The spectral signal 551 is dequantized by the dequantizing means 1551 (signal 552), and then the denormalizing means 1
It is denormalized by 552 and taken out as a signal 553.

FIG. 8 is a diagram for explaining a conventional coding method in the coding apparatus shown in FIG. In the example of this figure, the spectrum signal is obtained by the conversion means of FIG. 3, and FIG. 8 shows the absolute value of the MDCT spectrum by converting the level into dB. The input signal is converted into, for example, 64 spectral signals for each predetermined time block, which is, for example, from eight bands b1 to b8 (hereinafter,
These are called a coding unit), and normalization and quantization are performed. By changing the quantization accuracy for each coding unit depending on the distribution of frequency components, it is possible to perform audio-efficient coding that suppresses deterioration of sound quality to a minimum.

FIG. 9 shows a specific example of recording the signal encoded as described above on a recording medium.
In this specific example, a fixed-length header including a synchronization signal SC is attached to the beginning of each frame, and the number of coding units UN is also recorded therein. Next to the header, quantization precision information QN is recorded by the number of coding units, and thereafter, normalization precision information NP is recorded by the number of coding units. The normalized and quantized spectral coefficient information SP is recorded after that, but when the frame length is fixed, an empty area may be formed after the spectral coefficient information SP. In the example of this figure, the spectrum signal of FIG. 8 is encoded, and as the quantization accuracy information QN, for example, 6 bits of the lowest coding unit to 2 bits of the highest coding unit are shown. The normalization coefficient information NP is assigned as shown in the drawing from a value of 46 in the lowest coding unit to a value of 22, for example, in the highest coding unit. A value proportional to the dB value is used as the normalization coefficient information NP.

It is possible to further improve the coding efficiency with respect to the method described above. For example, in the quantized spectrum signal, a relatively short code length is assigned to a high frequency one, and a relatively long code length is assigned to a low frequency one, thereby improving coding efficiency. be able to. Also, for example, by increasing the length of the transform block, the amount of sub information such as quantization accuracy information and normalization coefficient information can be relatively reduced, and the frequency resolution can be increased, so that the quantization accuracy on the frequency axis is more elaborate. Since it can be controlled to, the encoding efficiency can be improved.

Furthermore, Japanese Patent Application No. 5-152865 or WO94 / 28633 which the present inventors have previously proposed.
In the specification and drawings of the above, a tonal component that is particularly important for hearing is separated from a spectrum signal, that is, a signal component in which energy is concentrated around a specific frequency,
A method of encoding separately from other spectral components has been proposed, which makes it possible to efficiently encode an audio signal or the like at a high compression rate with almost no auditory deterioration. ing.

FIG. 10 is a diagram for explaining a method of encoding by using such a method, in which particularly high levels are separated as tone components, for example, tone components Tn1 to Tn3 from the spectrum signal. Then, the state of encoding is shown. For each tone component Tn1 to Tn3,
The position information, for example, position data Pos1 to Pos3, is also required, but the spectrum signal after extracting the tone components Tn1 to Tn3 can be quantized with a small number of bits, so that energy can be transmitted to a specific spectrum signal. When such a method is applied to a concentrated signal, particularly efficient coding becomes possible.

FIG. 11 shows the signal component coding means 11 of FIG. 2 when the tone component is separated and coded as described above.
02 shows the configuration of No. 02. The conversion means 110 of FIG.
1 output signal 102 (signal 601 in FIG. 11) is output by the tone component separating means 1601 as the tone component (signal 60).
2) and the non-tone component (signal 603) are separated, coded by the tone component coding means 1602 and the non-tone component coding means 1603, respectively, and extracted as signals 604 and 605, respectively. Tone component coding means 1602 and non-tone component coding means 16
03 has the same configuration as that of FIG. 4, but the tone component encoding means 1602 also encodes the position information of the tone component.

Similarly, FIG. 12 shows the case of decoding the encoded one by separating the tone component as described above.
2 shows the configuration of the signal component decoding means 1402. The signal 701 in FIG. 12 corresponds to the signal 604 in FIG. 11, and the signal 702 in FIG. 12 corresponds to the signal 605 in FIG. The signal 701 is decoded by the tone component decoding means 1701 and is converted into the signal 703 by the spectrum signal synthesizing means 17
03, the signal 702 is sent to the non-tone component decoding means 17
It is decoded by 02 and sent to the spectrum signal synthesizing means 1703 as a signal 704. The spectrum signal synthesizing means 1703 synthesizes the tone component (signal 703) and the non-tone component (signal 704), and outputs it as a signal 705.

FIG. 13 shows a concrete example of recording the signal coded as described above on a recording medium. In this specific example, the tone components are separated and encoded, and the code string is recorded in the portion between the header portion and the quantization accuracy information QN. For the tone component sequence, the tone component number information TN is recorded first, and then the data of each tone component is recorded. Examples of the tone component data include position information P, quantization accuracy information QN, normalization coefficient information NP, and spectrum coefficient information SP. Further, in this specific example, the frequency resolution is increased by doubling the conversion block length for converting into a spectrum signal as compared with the specific example of FIG. By comparison, a code string of an acoustic signal corresponding to double the length is recorded in a frame having the same number of bytes.

The above description is for explaining the technique prior to the description of the embodiment of the present invention. However, in the embodiment of the present invention, for example, when applied to audio,
Allowing relatively low quality audio signals to be heard freely for previewing the content, and allowing high quality audio signals to be heard by purchasing a relatively small amount of additional data. Is.

That is, in the embodiment of the present invention, for example, as shown in FIG. 14, a dummy quantization precision in the quantization precision information QN is to be encoded as shown in FIG. As data, data indicating 0 bit allocation to four high-frequency side encoding units is encoded, and four high-frequency side encodings are used as dummy normalization coefficient data in the normalization coefficient information NP. The minimum value of the normalization coefficient information 0 is encoded in the unit (in this specific example, the normalization coefficient has a value proportional to the dB value). As described above, by setting the quantization accuracy information on the high frequency side to 0, the spectral coefficient information of the area Neg in FIG. 14 is actually ignored, and when this is reproduced by a normal reproducing apparatus, it becomes as shown in FIG. Narrow band data with the spectrum shown is reproduced. This can be used as data for trial listening. Also, by encoding dummy data for the normalization coefficient information, it becomes more difficult to guess the quantization accuracy information and illegally perform high quality reproduction.

Further, by writing dummy data in the portion of the spectral coefficient information which is ignored, the safety can be further improved. As will be described later, especially when the spectral coefficient information is encoded by the variable length code, even if only some of the spectral coefficient information is replaced with dummy data, the higher band data can be read correctly. It is more effective because it disappears.

Further, in the embodiment of the present invention, by changing the start position of the dummy data in the spectrum coefficient information for each frame, it becomes difficult to analogize the trial viewing data (the trial listening data), and the trial listening data is tried. We try to keep the safety level of viewing data high.

In the above example, both the quantization accuracy information and the normalization coefficient information are replaced with dummy data, but only one of them may be replaced with dummy data. When only the quantization accuracy information is dummy data of 0-bit data, the narrow band data having the spectrum as shown in FIG. 15 is reproduced. On the other hand, when only the normalization coefficient information is dummy data having a value of 0, the spectrum has a spectrum as shown in FIG. From the viewpoint of audibility, it is substantially the same as 0. In the embodiment of the present invention, this case will be referred to as a narrowband signal.

Regarding the data to be used as dummy data among the quantization precision information and the normalization coefficient information, there is a difference in the risk that these true values are guessed and high quality reproduction is performed. When both the quantization accuracy information and the normalization coefficient information are dummy data, there is no data for estimating their true values, so it is the safest. When only the quantization accuracy information is dummy data, for example, when the original bit allocation algorithm is to obtain the quantization accuracy information based on the normalization coefficient, the quantization accuracy information is obtained by using the normalization coefficient information as a clue. The risk is relatively high due to the risk of being guessed. On the other hand, since it is relatively difficult to obtain the normalization coefficient information from the quantization accuracy information, the method of using only the normalization coefficient information as dummy data is compared with the method of using only the quantization accuracy information as dummy data. And the risk is low. The quantization accuracy information or the normalization coefficient information may be selectively used as dummy data depending on the band.

In addition, part of the spectrum coefficient information may be replaced with dummy data of 0. In particular, since the mid-range spectrum is important in terms of sound quality, this part may be replaced with dummy data of 0, and the mid-high range part may be replaced with dummy quantization accuracy information or dummy normalization coefficient information. This dummy data does not necessarily have to be replaced with 0, but may be replaced with any code that is shorter than the code that represents a true numerical value when performing variable-length coding, for example. In that case, the band to be replaced by the dummy quantization accuracy information or the dummy normalization coefficient information covers the band in which a part of the spectrum coefficient information is replaced with the dummy data, so that the narrow band reproduction is correctly performed. In particular, when a variable length code is used for encoding the spectrum coefficient information, a part of the information in the middle band is lost, so that the data in the higher band cannot be decoded at all.

In any case, it is more difficult to guess a relatively large amount of data that has penetrated into the content of a signal, as compared with the case of deciphering a relatively short key length used in ordinary encryption. It can be said that there is a low risk that the rights of the copyright holders of Also, even if the dummy data is guessed for a certain song, unlike the case where the decryption method of the encryption algorithm is known, there is no possibility that damage will spread to other songs. It can be said that it is more secure than when encryption is applied.

FIG. 17 is a block diagram showing an example of a reproducing apparatus used in the embodiment of the present invention, which is an improvement of the conventional decoding means shown in FIG.

In FIG. 17, an input signal 801 is a code string (first code string) in which a part is replaced with dummy data. Here, the quantization accuracy information and normalization on the entire band or high band side are used. It is assumed that the coefficient information is dummy data.

FIG. 17 is a block diagram showing an example of a reproducing apparatus used in the embodiment of the present invention, which is an improvement of the conventional decoding means shown in FIG.

In FIG. 17, an input signal 801 is a code string (first code string) in which a part is replaced with dummy data. Here, the quantization accuracy information of the entire band or high band, and normalization are used. It is assumed that the coefficient information and the spectral coefficient information in the middle range are dummy data. A signal 80, which is a high-efficiency coded signal in which this dummy data is embedded
1 is, for example, a predetermined public line (ISDN: Integrated
(Service Digital Network, satellite line, analog line, etc.) and input to the coded sequence decomposing unit 1801, the content of the code sequence is decomposed by the code sequence decomposing unit 1801, and the code sequence rewriting unit 1802 as a signal 802. Sent to. The code string rewriting unit 1802
Through the control means 1805, the true quantization accuracy information, the normalization coefficient information, and the mid-range spectrum coefficient information 806 as the second code string that complements the dummy data portion are received as the signal 807, and thereby the signal 802 is received. The dummy quantization accuracy information, the normalization coefficient information, and the mid-range spectrum coefficient information are rewritten, and the resulting signal 803 is sent to the signal component decoding means 1803. The signal component decoding means 1803 decodes this data into spectrum data 804, and the inverse conversion means 1804 converts this into time series data 805 to reproduce an audio signal.

In the configuration of FIG. 17, in the case of the purchase mode, the true quantization accuracy information and / or the true normalization coefficient information and the true mid-range spectrum information 806 for rewriting the above-mentioned dummy data are added to the above-mentioned signal. Input to the control means 1805 via the same public line as 801. The control means 1805 controls the dummy data in the high-efficiency coded signal 801 in which the dummy data input to the code string rewriting means 1802 is embedded, into the true quantization precision information and / or the true normalization coefficient information and the true quantization coefficient information. The rewritten high-efficiency coded signal 803 is input to the signal component decoding means 1803 by using the mid-range spectrum information 806.

As a result, the user can listen to the listening music of low sound quality to which the dummy data is added in the trial viewing mode, and the high sound quality when the predetermined purchase procedure (billing process, authentication process, etc.) is performed. You can listen to music.

In the above-described specific example, the case where all the dummy data is rewritten (complemented) by using the second code string has been described, but the present invention is not limited to this.
It is also possible to rewrite and reproduce at least a part of the dummy data by using the partial code string of the second code string. As described above, when at least a part of the dummy data is replaced and reproduced by using the partial code string of the second code string, the ratio of the partial code string of the second code string is arbitrarily changed, For example, the quality of trial viewing (sound quality, image quality, etc.) can be arbitrarily changed.

In the above-described embodiment, the high-efficiency coded signal 801 in which the dummy data is embedded, the true quantization accuracy information for rewriting the dummy data, and / or the true normalization coefficient information, and the true middle range. Spectral information (second code string or partial code string thereof) 806 was obtained from the server side via the same public line, but for example, a high-efficiency coded signal in which dummy data with a large amount of data was embedded. 801 is obtained by a satellite line having a high transmission rate, and true quantization accuracy information and / or true normalization coefficient information and true mid-range spectrum information 806 with a small amount of data are compared with the transmission rate of a telephone line or ISDN. They may be obtained separately by using low-cost lines. In addition, the signal 801 is sent to the CD-ROM.
Alternatively, a large-capacity recording medium such as a DVD (Digital Versatile Disc) -ROM may be used. With the above configuration, security can be enhanced.

By the way, although the tone component and the non-tone component have been described with reference to FIG. 13, the high-efficiency coded signal in which the dummy data is embedded is the quantization accuracy information and / or the normalization coefficient forming the tone component. It may be performed on the information, may be performed on the quantization accuracy information and / or the normalization coefficient information that constitutes the non-tone component, or may be the quantization accuracy information on both the tone component and the non-tone component. And / or may be performed on the normalization factor information.

Next, FIG. 18 shows the control means 180 of FIG.
5 shows a specific example of the format of the true information (second code string) of the signal 807 from No. 5 and N shown in FIG.
This is for changing the information of the No. frame to the information shown in FIG. As a result, in the code string in which the dummy data is still contained, the reproduced sound having the spectrum shown in FIG. 15 is changed to the reproduced sound having the spectrum shown in FIG. Here, it is assumed that the mid-range spectrum coefficient information to be replaced with the dummy has a fixed length and starts from the leading code string where band limitation starts.

FIG. 19 is a block diagram showing an example of the recording means used in the embodiment of the present invention. In FIG. 19, an input signal 821 is a first code string in which a part is replaced with dummy data, and here, the quantization accuracy information on the high frequency side, the normalization coefficient information, and the true mid-range spectrum information are It is assumed to be dummy data. First, the contents of the code string are decomposed by the code string disassembling means 1821 and sent to the code string rewriting means 1822 as a signal 822. The code string rewriting means 1822 is the control means 18
24 through 24, the true quantization precision information, the normalization coefficient information, and the true mid-range spectrum information 825, which is the second code string.
Is received as signal 826, which results in signal 82
The portion of the dummy quantization precision information, the normalization coefficient information, and the true middle-range spectrum information of 2 is rewritten, and the resulting signal 823 is sent to the recording means 1823, and this is recorded on the recording medium. Note that the recording medium that records the code string of the signal 824 here may be the recording medium that originally recorded the code string of the signal 821.

In the embodiment of FIG. 19 as well, similar to the example of FIG. 17 described above, instead of rewriting (complementing) all the dummy data using the second code string, the dummy data At least a part may be rewritten and recorded using the partial code string of the second code string. As described above, when at least a part of the dummy data is replaced with the partial code string of the second code string and recorded, by changing the ratio of the partial code string of the second code string, For example, the quality of trial viewing (sound quality, image quality, etc.) can be arbitrarily changed. In this case, even in the trial viewing mode, the partial code string of the second code string is the control means 1824 as the signal 825.
To the signal 826 and the code string rewriting means 1
Since it is sent to 822, a part of the dummy data embedded in the first code string from the code string decomposing means 1821 is rewritten by using the partial code string of the second code string and sent to the recording means 1823. Good.

Although the reproducing apparatus and the recording apparatus used in the embodiments of the present invention have been described above, here, the spectral coefficient information on the high frequency side is encrypted to further enhance the security. It is also possible to In that case, the code string rewriting means 1802, 1822 for replacing the dummy data in FIG. 17 and FIG. Data on the high frequency side is decrypted by using the decryption key obtained through 1824, and is reproduced or recorded.

FIG. 20 shows a concrete example of the format of information for replacing dummy data when the tone components are separated as shown in FIG. 10 and encoded as shown in FIG. As a result, the reproduced sound having the spectrum shown in FIG. 15 changes to the reproduced sound having the spectrum shown in FIG. Here, it is assumed that the mid-range spectrum coefficient information to be replaced with the dummy starts from the first code string having a fixed length and the band limitation starts.

FIG. 21 is an example of a flowchart showing a procedure in the case of performing reproduction by using software in the reproducing method used in the embodiment of the present invention. First, in step S11, a code string (first code string) including dummy data is decomposed, and then in step S12,
Determines whether to perform high quality playback. When high-quality sound reproduction is performed, in step S13, the dummy data in the first code string is replaced with true data (second code string) for giving a wide band, and then in step S13.
14. If not, go directly to step S1.
Go to 4. In step S14, the signal component is decoded, and in step S15, the time series signal is inversely converted to reproduce the sound.

FIG. 22 is an example of a flow chart showing the procedure when recording is performed using software in the recording method used in the embodiment of the present invention. First, in step S21, it is determined whether or not high quality sound recording is to be performed. If high quality sound recording is to be performed, first, step S21 is performed.
In step 22, the code string (first code string) including the dummy data is decomposed, and then in step S23, the dummy data in the code string is converted into true data (second code string) having a wide band. After the replacement, the process proceeds to step S24 to record, otherwise, to step S24.
The process directly proceeds from step 21 to step S24.

By the way, in the example of FIG.
Although the data amount of the true mid-range spectrum coefficient information is fixed length, in the embodiment according to the present invention, as shown in FIG. 23, the total length of the true data for one frame is fixed length. Therefore, for example, the data amount of the mid-range spectrum coefficient information is made variable in accordance with the data amount of the true tone component normalization coefficient information whose number varies depending on the frame. In this way, for example, if the length of the entire true data for one frame is set to 16 bytes, for example, when the true data is encrypted using DES, the DES Since two blocks correspond to each other, it is necessary to perform the DES block processing twice for one frame processing, and the control can be simplified because of synchronization. FIG. 23 shows an encoding state for one frame when the true information is encoded in this way, in which the length of the entire frame is constant and the last true mid-range spectrum coefficient is obtained. The amount of information data is variable.

In the above embodiment, if the data amount of the mid-range spectrum coefficient information is variable, the safety is reduced in the portion where the dummy data amount is small.
Since there are a large number of frames in succession, there are also frames with a large amount of dummy data, and it is possible to secure sufficient safety as a whole. In addition, even if the true data size of each frame is not necessarily fixed, for example, DE
When S is used, if it is an integer multiple of 8 bytes, it is not as easy as when the amount of data is completely fixed. For example, how many times the number of frames is 8 bytes at the beginning of true data? Is recorded and the DES is decrypted by that number, thereby enabling relatively simple control.

Here, FIG. 24 is a diagram for explaining a case where true data for quality improvement is generated for all frames in the code string generation device of the embodiment of the present invention as described above. It is an example of a flowchart. First, in step S31, the control variable I is set to 1
Then, in steps S32, S33, and S34, true tone component relationship information, true quantization accuracy relationship information, and true normalization coefficient relationship information are generated, respectively. Then, in step S35, the dummy data amount of the mid-range spectrum is calculated so that the information amount (data amount of the second code string) for improving the quality for one frame is constant or becomes an integral multiple of the predetermined data amount. Go to step S
In step S37, true mid-range spectrum related information is generated, and then in step S37, DES for two blocks is generated.
It has been encrypted. In step S38, it is checked whether or not this frame is the last frame, and if so, the processing ends, and if not, otherwise.
In step S39, the control variable I is incremented by 1, and the process returns to step S32 to process the next frame. As described above, according to the method of the present invention, generation of true data for high quality can be performed in synchronization with processing of a block cipher such as DES.

Next, FIG. 25 is a block diagram showing an example of a reproducing apparatus according to an embodiment of the present invention, which is an improvement of the reproducing apparatus described with reference to FIG. This Figure 2
5, the control means 1845 sends the high-quality data (second code string) 846, which has a fixed length for one frame or an integral multiple of a predetermined data amount, to the medium. Area spectrum dummy data amount calculation means 1846
Then, the amount of dummy data of the mid-range spectrum is calculated. Data 847 is transmitted and received between the control means 1845 and the mid-range spectrum dummy data amount calculation means 1846, and the data 848 for complementing the dummy data from the control means 1845 is the code string rewriting means 184.
Sent to 2. Other configurations are the same as those in FIG.
Each part 1841 to 1845 and signals 841 to 84 of FIG.
Reference numeral 6 denotes each unit 1801 to 1805 and signal 801 in FIG.
To 806, the description thereof will be omitted.

Similarly, FIG. 26 is a block diagram showing an example of a recording apparatus according to an embodiment of the present invention, which is an improvement of the recording apparatus described with reference to FIG. Middle-range spectrum dummy data amount calculation means 1865 for the high-quality data sent in
Then, the amount of dummy data of the mid-range spectrum is calculated. The parts 1861 to 1864 and the signals 861 to 865 shown in FIG. 26 correspond to the parts 1821 to 18 shown in FIG.
24 and signals 821 to 825, respectively,
The description is omitted.

Next, FIG. 27 shows an example of a flow chart for explaining a case where true data for quality improvement is rewritten for all frames in the embodiment of the present invention. It is a thing. First, step S4
In 1, the control variable I is set to 1, and in step S42, the DES cipher for two blocks is decrypted. Next, in steps S43, S44, and S45, the true tone component relationship information, the true quantization precision relationship information, and the true normalization coefficient relationship information are rewritten, respectively. After that, in step S46, the amount of dummy data of the mid-range spectrum is calculated so that the amount of information for improving the quality for one frame becomes constant, and then in step S47, the information about the true mid-range spectrum is obtained. Is being rewritten. In step S48, it is checked whether or not this frame is the last frame, and if so, the processing is terminated, and if not, in step S48.
At 49, the control variable I is incremented by 1, and the process returns to step S42 to process the next frame. As described above, according to the method of the present invention, it is possible to rewrite the dummy data to the true data for improving the quality in synchronization with the processing of the block cipher such as DES.

In the above description, the trial listening is performed by the trial listening data, for example, the trial listening data such as music,
As a result, if you like it, I explained how to improve the sound quality by purchasing high sound quality data, but the above method is one of the important things in terms of security. How to keep the band spectral coefficient information unknown. One way to do this is to replace as much of the true mid-range spectrum coefficient information with dummy data as possible, but it is not possible to know the location of the mid-range spectrum coefficient information that was actually replaced with dummy data. Also, security can be improved by setting.
Therefore, in the embodiment of the present invention, this is realized by changing the position of the true mid-range spectrum coefficient information depending on the frame. In the following description, a more secure case of encoding the spectrum coefficient information using a variable length code will be described, but the method of the present invention can be applied to a case where the variable length code is not necessarily used. is there.

In order to realize the above, FIG.
FIG. 29 shows an embodiment in which the true middle-range spectrum coefficient information head position is added to the true information code string for replacing the position of the true middle-range spectrum coefficient information with the dummy data. It shows that the start position of the coefficient information is changed for each frame.

FIG. 30 shows a preview file containing dummy data while changing the start position of the true mid-range spectrum coefficient information, and a high-quality sound file containing information replacing dummy data, in accordance with the method described above. It is a flow chart for explaining a concrete example of a creating method.

In FIG. 30, first, step S5
In step 1, the control variable I = 1 is set, and the flow proceeds to step S52 to dummy the tone spectrum component normalization coefficient.
That is, the normalization coefficient of the tone spectrum component of the trial listening file is set to 0, and the true value is encoded and recorded in the high-quality sound file. Next, in step S53, the non-tone spectral component normalization coefficient is made dummy. That is, the normalization coefficient of the non-tone spectrum component of the sample file is set to 0, and the true value is encoded and recorded in the high quality file. In the next step S54, a pseudo random number is generated as R. As a method of generating a pseudo-random number, for example, a method of first selecting an arbitrary number of 100 digits, squaring it, and taking the central 100 digits is repeated, but the method is not limited to this. Not something.

Next, in step S55, R
Is divided by 128 to be r (r = R% 128), and r is encoded in step S56 and recorded in the high-quality sound file. Next, in step S57, dummy conversion is performed from the r-th bit of the band-limited region. That is, a predetermined number of bits from the r-th bit of the trial listening file is replaced with another data, and the true value of that portion is recorded in the high-quality sound file. Here, as a pattern for replacing from the r-th bit of the sample file, all the values are set to 0 or the like so that the location can be known at a glance
It is preferable that the positions of the dummy data are hard to be guessed by making the values mixed. At this time, it is preferable to configure the dummy data with a value having a shorter code length than the true data to prevent the decoder from decoding the code string and decoding up to the adjacent frame. In the next step S58, it is checked whether or not the frame is the final frame. If the frame is the final frame, the process is terminated.
In step 59, the value of I is incremented by 1 and then step S
Return to 52.

Next, FIG. 31 is a flow chart for explaining an example of the flow of processing in the case where a file capable of high-quality sound reproduction is generated from the above-mentioned trial listening file and high-quality sound file.

In step S61 of FIG. 31, the control variable I = 1 is set, and the flow advances to step S62. Step S
At 62, the dummy data of the normalization coefficient of the tone spectrum component of the sample file is canceled using the value of the true normalization coefficient of the high quality file. Next step S63
Then, similarly, the dummy data of the normalization coefficient of the non-tone spectrum component of the preview file is canceled using the value of the true normalization coefficient of the high-quality file. Next, in step S64, the value of r is read out, and in step S65
In, the dummy data from the r-th bit of the band limited area of the sample file is replaced with the true mid-range spectrum coefficient information of the sound quality improving file, and the process proceeds to step S66. In step S66, it is checked whether or not it is the last frame. If it is the last frame, the process is terminated. If not, the process proceeds to step S67, the value of I is incremented by 1, and the process proceeds to step S62. Return.

By the way, the specific example of changing the position of the mid-range spectrum coefficient information to be replaced with the dummy data described above for each frame and the specific example of the case of decoding are not limited to the example of the above-mentioned embodiment. . For example, the frame number is added to the value of r, and the value of the addition result is 12
The remainder obtained by dividing by 8 may be set to q, and a value obtained by converting the value of q using a random number table may be used instead of the above r in the above embodiment. In this case, it is also possible to write the value of q in the high-quality sound file and obtain the start position of the dummy data by using the same random number table as described above when improving the sound quality. By doing so, it becomes more difficult to illegally obtain the start position of the dummy data, and the safety can be further improved.

Instead of using the pseudo-random number, a random voltage is generated by, for example, applying a changing voltage to an A / D converter with poor accuracy and collecting the least significant bits after the A / D conversion, for example, 7 bits. May be. This also makes it possible to further enhance safety.

As yet another method, FIG.
The initial value of the pseudo-random number in step S54 is recorded in the high-quality sound file, and at the time of high-quality sound, the same calculation as when the start position of the dummy data of the viewing file is obtained, that is, step S54 in FIG. The calculation in S55 may be performed on the decoder side. By doing so, it becomes unnecessary to record the value of r for each frame in the high-quality file, and the data amount of the high-quality file can be reduced.

Further, in the above-mentioned embodiment, the head position of the dummy data is changed for each frame, but the head position of the dummy data may be changed for every plurality of frames (at a plurality of frame cycles). Alternatively, the number of frames of the plurality of frames may be changed.

Although the case where an audio signal is used has been described above as an example, the present invention can also be applied to an image signal. That is, for example, when an image signal is transformed for each block using a two-dimensional DCT and is quantized using various quantization tables, a high-frequency component is dropped as a dummy quantization table. Is specified, and in order to improve the image quality, it is possible to perform the same processing as in the case of an audio signal by adopting a method of replacing with a true quantization table that does not drop high frequency components. .

Of course, the method of the present invention can also be applied to a system in which the entire code string is encrypted and is reproduced while decrypting the code at the time of reproduction.

Further, in the above-described embodiments, the case where the coded bit stream is recorded on the recording medium has been described, but the present invention is also applicable to the case of transmitting the bit stream. Thus, for example, it is possible to reproduce high-quality sound only for a listener who has obtained a true normalization coefficient over the entire band of the audio signal being broadcast, and other listeners can fully understand the content, It is possible to enable reproduction with relatively low sound quality.

[0113]

In the signal reproducing apparatus and method according to the present invention, when reproducing a code string obtained by coding a signal in frame units, a part of the code string is dummy data. Rewriting of rewriting the dummy data to the second code sequence that complements the dummy data portion for the code sequence,
Since the rewritten code string is decoded and the position of the dummy data of the first code string is changed, the size of the quality-improved data including the second code string is kept relatively small. As it is, it is possible to make it difficult to analogize the trial viewing data including the first code string, and to keep the safety level of the trial viewing data high.

[Brief description of drawings]

FIG. 1 is a block diagram showing a schematic configuration of an optical disc recording / reproducing apparatus provided for explaining an embodiment of the invention.

FIG. 2 is a block diagram showing a schematic configuration of an example of an encoding device provided for explaining an embodiment of the present invention.

FIG. 3 is a block diagram showing a specific example of conversion means of the encoding device in FIG.

FIG. 4 is a block diagram showing a specific example of signal component encoding means of the encoding device of FIG.

FIG. 5 is a block diagram showing a schematic configuration of an example of a decoding device provided for explaining an embodiment of the present invention.

FIG. 6 is a block diagram showing a specific example of inverse transform means of the decoding device of FIG.

7 is a block diagram showing a specific example of signal component decoding means of the decoding device in FIG.

[Fig. 8] Fig. 8 is a diagram for describing an encoding method used for describing an embodiment of the present invention.

[Fig. 9] Fig. 9 is a diagram for describing an example of a code string obtained by the encoding method used in the description of the embodiment of the present invention.

[Fig. 10] Fig. 10 is a diagram for describing another example of the encoding method used for describing the embodiment of the present invention.

FIG. 11 is a block diagram showing an example of a signal component coding means for realizing the coding method described with reference to FIG.

FIG. 12 is a block diagram showing an example of signal component decoding means used in a decoding device for decoding the code string obtained by the coding method described with reference to FIG.

13 is a diagram showing an example of a code string obtained by the encoding method described with reference to FIG.

FIG. 14 is a diagram showing an example of a code string obtained by the encoding method used in the embodiment of the present invention.

FIG. 15 is a diagram showing an example of a spectrum of a reproduction signal when a code string obtained by the encoding method described with reference to FIG. 14 is reproduced.

16 is a diagram showing an example of a spectrum of a reproduction signal when a code string obtained by another example of the encoding method described with reference to FIG. 14 is reproduced.

FIG. 17 is a diagram showing a schematic configuration of a reproducing device for realizing the encoding method described with reference to FIG. 15.

18 is a diagram showing an example of information for replacing dummy data of a code string obtained by the encoding method described with reference to FIG.

FIG. 19 is a block diagram showing a schematic configuration of a recording apparatus used in the embodiment of the present invention.

FIG. 20 is a diagram showing an example of information for replacing dummy data of a code string obtained by the encoding method used in the embodiment according to the present invention.

FIG. 21 is a flowchart for explaining a reproducing method used in the embodiment of the present invention.

FIG. 22 is a flowchart for explaining a recording method used in the embodiment of the present invention.

FIG. 23 is a diagram showing an example of a code string obtained by another coding method used in the embodiment of the present invention.

FIG. 24 is a flowchart for explaining an operation in the code string generation device according to the embodiment of the present invention.

FIG. 25 is a block diagram showing an example of a reproducing device according to an embodiment of the present invention.

FIG. 26 is a block diagram showing an example of a recording device according to an embodiment of the present invention.

FIG. 27 is a flowchart for explaining a true data rewriting operation for improving quality in the embodiment of the present invention.

FIG. 28 is a diagram showing an example of an information format for rewriting dummy data with true information according to the present invention.

FIG. 29 is a diagram showing a specific example of information for rewriting dummy data with true information according to the present invention.

FIG. 30 is a flow chart for explaining an example of generating a trial listening file and its high-quality sound file according to the present invention.

FIG. 31 is a flow chart for explaining an example of generating a high-quality sound file by integrating a trial listening file and its high-quality sound file according to the present invention.

[Explanation of symbols]

1801, 1821, 1841, 1861 code string decomposing means, 1802, 1822, 1842, 1862 code string rewriting means, 1803, 1843 signal component decoding means, 1804, 1844 inverse transforming means, 180
5, 1824, 1845, 1853, 1864 control means, 1823, 1863 recording means, 1851 encoding means, 1842, 1862 code string rewriting means,
1846, 1865 Mid-range spectrum dummy data amount calculation means

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Kenzo Akagi             6-735 Kita-Shinagawa, Shinagawa-ku, Tokyo Soni             -Inside the corporation F-term (reference) 5D044 AB05 BC06 CC06 DE02 DE03                       DE12 DE50 GK08 GK17 HL08                 5D045 DA01 DA11

Claims (33)

[Claims] 1. A signal reproducing method for reproducing a code string obtained by encoding a signal in a predetermined unit, wherein a first code string in which a part of the code string is dummy data is input. In the code string input step, and when a second code string for complementing the dummy data part is input, at least a part of the dummy data part in the first code string is input to the second code. There is a complementing step of complementing using a column, and a decoding step of decoding the code string or the first code string complemented by the complementing step, and the position of the dummy data of the first code string is A signal reproducing method characterized by being variable in the predetermined unit. 2. The signal reproducing method according to claim 1, wherein the dummy data is provided in the first code string for each of the predetermined units. 3. The signal reproducing method according to claim 1, wherein the dummy data of the first code string has a head position that changes every predetermined unit. 4. The signal reproducing method according to claim 1, wherein the code string includes a variable length code, and at least a part of the dummy data is for the variable length code. 5. In the above encoding, an input signal is spectrum-converted and band-divided to generate a code string of a predetermined format including quantization accuracy information, normalization coefficient information, and spectrum coefficient information for each band. 2. The signal reproducing method according to claim 1, wherein the dummy data includes at least data corresponding to a part of the spectral coefficient information. 6. The spectrum coefficient information is encoded by a variable length code, and the dummy data of the first code string is original data when encoded by the variable length code. 6. The signal reproducing method according to claim 5, wherein the encoded data has a length equal to or less than the encoded data. 7. A signal reproducing apparatus for reproducing a code string obtained by encoding a signal in a predetermined unit, wherein a first code string in which a part of the code string is dummy data is input. When a code string input means and a second code string for complementing the dummy data part are input, at least a part of the dummy data part in the first code string is input to the second code. Complementary means for complementing using a column, and decoding means for decoding the code string or the first code string complemented by the complementing means, the position of the dummy data of the first code string, A signal reproducing apparatus characterized by being variable in the predetermined unit. 8. The signal reproducing apparatus according to claim 7, wherein the dummy data is provided in the first code string for each of the predetermined units. 9. The signal reproducing apparatus according to claim 7, wherein the dummy data of the first code string has a head position that changes every predetermined unit. 10. In the encoding, the input signal is subjected to spectrum conversion, band division, and a code string of a predetermined format including quantization accuracy information, normalization coefficient information, and spectrum coefficient information for each band. The signal reproduction device according to claim 7, wherein the generated dummy data includes data corresponding to at least a part of the spectral coefficient information. 11. The spectrum coefficient information is encoded by a variable length code, and the dummy data of the first code string is original data when encoded by the variable length code. 11. The signal reproducing apparatus according to claim 10, wherein the encoded data has a length equal to or shorter than the coded data. 12. A signal recording method for recording a code sequence obtained by encoding a signal in a predetermined unit on a recording medium, wherein a first code sequence in which a part of the code sequence is dummy data is input. In the first code string input step, and when a second code string for complementing the dummy data part is input, at least a part of the dummy data part in the first code string is input to the first code string. The signal recording method is characterized in that the position of the dummy data of the first code string is variable in the predetermined unit. 13. The signal recording method according to claim 12, wherein the dummy data is provided in the first code string for each of the predetermined units. 14. The signal recording method according to claim 12, wherein the dummy data of the first code string has a head position that changes for each of the predetermined units. 15. In the above encoding, an input signal is spectrum-converted and band-divided to generate a code string of a predetermined format including quantization accuracy information, normalization coefficient information, and spectrum coefficient information for each band. 13. The signal recording method according to claim 12, wherein the dummy data corresponds to at least a part of the spectral coefficient information. 16. The spectral coefficient information is encoded by a variable length code, and the dummy data of the first code string is original data when encoded by the variable length code. 16. The signal recording method according to claim 15, wherein the coded data has a length equal to or shorter than the encoded data. 17. A signal recording device for recording a code sequence obtained by encoding a signal in a predetermined unit on a recording medium, wherein a first code sequence in which a part of the code sequence is dummy data is input. When the first code string inputting means and the second code string for complementing the dummy data part are input, at least a part of the dummy data part in the first code string is input to the first code string input means. A signal recording device, comprising: a complementing unit that complements using a second code string, wherein the position of the dummy data of the first code string is variable in the predetermined unit. 18. The signal recording device according to claim 17, wherein the dummy data is provided in the first code string for each of the predetermined units. 19. The signal recording apparatus according to claim 17, wherein the dummy data of the first code string has a head position that changes every predetermined unit. 20. In the encoding, an input signal is spectrum-converted and band-divided to generate a code string of a predetermined format including quantization accuracy information, normalization coefficient information, and spectrum coefficient information for each band. 18. The signal recording apparatus according to claim 17, wherein the dummy data includes at least data corresponding to a part of the spectral coefficient information. 21. The spectrum coefficient information is encoded by a variable length code, and the dummy data of the first code string is original data when encoded by the variable length code. 21. The signal recording device according to claim 20, wherein the encoded data has a length equal to or shorter than the encoded data. 22. An encoding step of generating a code string of a predetermined format by encoding an input signal, and a step of rewriting a part of the code string of the predetermined format into dummy data to generate a first code string. A first code string generating step, and a second code string generating step of extracting a part of the code string of the predetermined format according to the position of the dummy data to generate a second code string, The code string generating method, wherein the position of the dummy data of the code string No. 1 is variable in a predetermined unit. 23. The code string generating method according to claim 22, wherein the dummy data is provided for each of the predetermined units in the first code string. 24. The code string generating method according to claim 22, wherein the dummy data of the first code string has a head position that changes every predetermined unit. 25. The code string generating method according to claim 22, wherein the code string includes a variable length code, and at least a part of the dummy data is for the variable length code. 26. In the above encoding, an input signal is spectrum-converted and band-divided to generate a code string of a predetermined format including quantization accuracy information, normalization coefficient information and spectrum coefficient information for each band. 23. The code string generation method according to claim 22, wherein the dummy data includes at least data corresponding to a part of the spectral coefficient information. 27. The spectrum coefficient information is encoded by a variable length code, and the dummy data of the first code string is original data when encoded by the variable length code. 27. The code string generation method according to claim 26, wherein the coded data has a length equal to or less than the coded data of. 28. Coding means for generating a code string of a predetermined format by coding an input signal; and a first code string for rewriting a part of the code string of the predetermined format into dummy data. And a second code string generating means for extracting a part of the code string of the predetermined format corresponding to the position of the dummy data to generate a second code string. The code string generating device is characterized in that the position of the dummy data of the code string No. 1 is variable in a predetermined unit. 29. The code string generation device according to claim 28, wherein the dummy data is provided in the first code string for each of the predetermined units. 30. The code string generation apparatus according to claim 28, wherein the dummy data of the first code string has a head position that changes every predetermined unit. 31. The code string generating apparatus according to claim 28, wherein the code string includes a variable length code, and the dummy data is for the variable length code. 32. In the encoding, an input signal is spectrum-converted and band-divided to generate a code string of a predetermined format including quantization accuracy information, normalization coefficient information and spectrum coefficient information for each band. 29. The code string generation device according to claim 28, wherein the dummy data includes data corresponding to at least a part of the spectral coefficient information. 33. The spectrum coefficient information is encoded by a variable length code, and the dummy data of the first code string is original data when encoded by the variable length code. 33. The code string generation device according to claim 32, which has a length equal to or shorter than the encoded data of.