JP2004362721A - Method and device for creating data, method and device for reproducing data, and program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent unnecessary noise from being outputted when reproducing a partly enciphered audio code train. <P>SOLUTION: The audio code train is composed of enciphered frames including enciphered data and silence data, and frames not including enciphered data. In a decoder, when a cipher deciphering key which is recorded in the enciphered frames and decodes the enciphered data is not acquired, the enciphered data are not reproduced for the reproduction period of the enciphered frames, but silence is outputted (sound is not outputted) based on the silence data. Therefore, for the reproduction periods of the frames 1 to 3 and the frames 7 to 9, sound is not outputted. Moreover, for the reproduction periods of the frames 4 to 6, sound for audition is outputted on the basis of a code train described in each frame. This invention is applicable to a personal computer capable of processing an audio code train. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a data generation method and a data generation device, a data reproduction method and a data reproduction device, and a program, and in particular, to a data generation method capable of generating or reproducing audio data that can obtain a more suitable reproduced sound. The present invention relates to a data generation device, a data reproduction method, a data reproduction device, and a program.
[0002]
[Prior art]
As a recording medium for recording encoded audio signals, audio signals, and the like, for example, a magneto-optical disk such as an MD (Mini Disk) (trademark) is widely used. Various high-efficiency encoding methods have been proposed for recording the data.
[0003]
For example, a band division coding (SBC (Sub Band Coding)) in which an audio signal on the time axis is divided into a plurality of frequency bands and encoded without being divided into blocks, or a signal on the time axis is converted into a signal on the frequency axis. There is a blocking frequency band division method (so-called conversion coding) in which spectrum is converted into a plurality of frequency bands and encoded for each band. In addition, a technique has been considered in which, after band division is performed by band division encoding, in each band, a signal is spectrum-converted into a signal on the frequency axis, and encoding is performed for each band subjected to spectrum conversion.
[0004]
The filter used here is, for example, a quadrature mirror filter (QMF). E. FIG. The details are described in Non-Patent Document 1 by Crochiere. Also, Joseph H. et al. Non-Patent Document 2 by Rothweiler describes a filter dividing method with equal bandwidth.
[0005]
As the above-described spectral transform, for example, an input audio signal is divided into blocks in a predetermined unit time (frame), and a discrete Fourier transform (DFT), a discrete cosine transform (DCT) is performed for each block. Cosine Transform) and Modified DCT Transform (MDCT (Modified Discrete Cosine Transform)). Details of MDCT among these are described in J. Amer. P. Princen, A .; B. Bradley (Univ. Of Surrey Royal Melbourne Inst. Of Tech.) Et al.
[0006]
Further, when DFT or DCT is used as a method for spectrally transforming a waveform signal, if the transform is performed in a time block including M samples, M independent real number data can be obtained. In order to reduce connection distortion between time blocks, N / 2 samples are usually overlapped with blocks on both sides, that is, N samples are combined on both sides. Therefore, in DFT and DCT, on average, , (M + N / 2) samples are quantized and coded for M independent real number data.
[0007]
On the other hand, when the MDCT is used as a method for performing spectrum conversion, if the conversion is performed using a time block consisting of M samples, M / 2 blocks are used for each of the blocks adjacent to each other, that is, the M blocks are combined on both sides. Since M independent real number data can be obtained from 2M overlapping samples, the MDCT quantizes and encodes M real number data for M samples on average in MDCT. Will do.
[0008]
In the decoding device, a waveform signal can be reconstructed by adding the waveform elements obtained by inversely transforming each block from the code obtained by using the MDCT while causing the blocks to interfere with each other.
[0009]
In general, lengthening the time block for the transformation increases the frequency resolution of the spectrum and concentrates energy on specific spectral components. Therefore, by using a MDCT in which the conversion is performed with a long block length by overlapping the adjacent blocks by half, and the number of obtained spectral signals does not increase with respect to the number of time samples on which the conversion is based. By performing the transform, encoding can be performed more efficiently than in the case where DFT or DCT is used for the transform. In addition, by providing a sufficiently long overlap between adjacent blocks, distortion between blocks of a waveform signal can be reduced.
[0010]
As described above, by quantizing the signal divided for each band by filtering or spectral conversion, it is possible to control the band in which quantization noise occurs, and to utilize the properties such as the masking effect to improve the auditory Thus, more efficient encoding can be performed. Further, by performing normalization for each band, for example, with the maximum value of the absolute value of the signal component in the band before performing the quantization, it is possible to perform more efficient encoding.
[0011]
When quantizing each frequency component divided into frequency bands, the frequency division width may be determined in consideration of, for example, human auditory characteristics. That is, the audio signal may be divided into a plurality of bands (for example, 25 bands) such that a higher band generally called a critical band (critical band) has a wider bandwidth.
[0012]
Further, when the band is divided so that the critical band is widened, when data for each band is encoded, a predetermined bit distribution may be performed for each band, or the band may be adapted for each band. Bits may be allocated (bit allocation is performed).
[0013]
For example, when coefficient data obtained by MDCT is encoded by bit allocation, the number of bits is adaptively assigned to MDCT coefficient data for each band obtained by MDCT for each block, Encoding is performed. As bit allocation methods, for example, two methods described in Non-Patent Documents 4 and 5 are known.
[0014]
R. Zelinski, P .; Non-Patent Document 4 by Noll et al. Describes that bit allocation is performed based on the magnitude of a signal for each band. According to this method, the quantization noise spectrum becomes flat and the noise energy is minimized. Absent.
[0015]
Further, M. A. Non-Patent Document 5 by Kransner (Massachusetts Institute of Technology) describes a method of obtaining a required signal-to-noise ratio for each band and performing fixed bit allocation by using auditory masking. I have. 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.
[0016]
In order to solve these problems, all bits that can be used for bit allocation are divided into a fixed bit allocation pattern predetermined for each small block and a bit allocation depending on the signal size of each block. High-efficiency coding has been proposed in which division is used, and the division ratio is dependent on a signal related to the input signal, and the smoother the spectrum of the signal, the larger the division ratio into fixed bit allocation patterns is increased. ing.
[0017]
By using this method, when energy is concentrated on a specific spectrum such as a sine wave input, a large number of bits can be allocated to a block including the spectrum, so that the overall signal-to-noise characteristic is improved. Can be significantly improved. In general, human hearing to a signal having a steep spectral component is extremely sensitive. Therefore, improving the signal-to-noise characteristics using such a method requires not only measurement characteristics but also human characteristics. Is effective in improving the quality of the sound actually heard.
[0018]
Many methods for bit allocation have been proposed in addition to those described above. Furthermore, the model related to hearing has been refined, and the capability of the coding apparatus has been improved, so that it is possible to perform not only the characteristic value on measurement but also coding with higher efficiency for human hearing. I have. In these methods, a real-valued bit allocation reference value for realizing the signal-to-noise characteristic obtained by the calculation as faithfully as possible is obtained, and an integer value approximating the real-valued bit allocation reference value is obtained and set to the number of allocated bits. Generally, it is done.
[0019]
In Patent Documents 1 and 2 filed earlier by the present applicant, from the generated spectral signal, energy is concentrated on a tonal component that is particularly important in hearing, that is, around a specific frequency. A method of separating such components and encoding them separately from other spectral components is described. According to this method, it is possible to effectively encode an audio signal or the like at a high compression ratio with almost no auditory deterioration.
[0020]
When an actual code sequence is generated, first, for each band in which normalization and quantization are performed, quantization accuracy information and normalization coefficient information are encoded with a predetermined number of bits, and then normalization and The quantized spectral signal is encoded. Also, ISO / IEC 11172-3; (1993 (E), a933) describes a high-efficiency coding scheme in which the number of bits representing quantization accuracy information is set to be different depending on the band, and the band is high. It is standardized so that the number of bits representing quantization accuracy information decreases as the frequency band becomes smaller.
[0021]
Instead of directly encoding the quantization accuracy information, a method of determining the quantization accuracy information from the normalization coefficient information in the decoding device, for example, is also known. Since the relationship between the quantization coefficient information and the quantization accuracy information is determined, it will not be possible to introduce control using quantization accuracy based on a more advanced auditory model in the future. Further, when there is a range in the compression ratio to be realized, it becomes necessary to determine the relationship between the normalization coefficient information and the quantization accuracy information for each compression ratio.
[0022]
As a method for encoding the quantized spectrum signal more efficiently, for example, D.I. A. As described in Non-Patent Document 6 by Huffman, a method of efficiently performing encoding using a variable-length code is also known.
[0023]
By the way, as disclosed in Patent Document 3, with respect to the music data coded as described above, a preview that can be reproduced only with low sound quality is created by limiting the preview band. It is known to distribute data to users. Thereby, the user can grasp the entirety of the original music data although the sound quality is low. If the user listens to the sample data and likes it, the user can restore the original music data by purchasing only the information that can restore the sample data to the original music data with high sound quality. Can be used.
[0024]
It is also known as a method of creating trial data that, of encoded music data, only some frames are encrypted and unencrypted portions are used as trial data. If the user listens to the trial listening data and likes it, the user separately purchases a key for decrypting the encryption, and uses the key to use the original music data. According to this, in order to restore the original data from the trial listening data, it is only necessary to download (acquire) only key data having a relatively small data amount. Thus, communication time can be reduced. For example, as this encryption method, there is DES (Data Encryption Standard) described in Non-Patent Document 6.
[0025]
[Patent Document 1]
Japanese Patent Application No. 5-152865
[Patent Document 2]
WO 94/28633 pamphlet
[Patent Document 3]
JP-A-10-135944
[Non-patent document 1]
"Digital coding of speech in subbands"
(BellSys.Tech.J.Vol.55, No.8 1974)
[Non-patent document 2]
"Polyphase Quadrature Fitters-A new subband coding technique"
(ICASSP 83, BOSTON)
[Non-Patent Document 3]
"Subband / Transform Coding Using Filter Bank Designs Based on Time Domain Aliasing Cancellation"
(ICASSP 1987)
[Non-patent document 4]
"Adaptive Transform Coding of Speech Signals"
(IEEE Transactions of Acoustics, Speech, and Signal Processing, Vol. ASSP-25, No. 4, August 1977)
[Non-Patent Document 5]
"The critical band coder digital encoding of the perceptual requirements of the auditory system"
(ICASSP 1980)
[Non-Patent Document 6]
"Federal Information Processing Standards Publication 46Specifications for the DATA ENCRYPTION STANDARD" (1977, January 15)
[0026]
[Problems to be solved by the invention]
However, as described above, when only a part of the frames are encrypted and used as the trial data, a normal playback device that plays the trial data (processing music data in a format in which some frames are encrypted) is performed. In the case of an apparatus that cannot perform encryption, even if an encrypted frame is reproduced as a normal unencrypted code string, serious noise may be generated.
[0027]
This gives the user who listened to the trial data uncomfortable feelings, and discourages the purchase of the original music data, which is not preferable for the content distributor. In addition, there is a possibility that a speaker that outputs such noise may be adversely affected.
[0028]
The present invention has been made in view of such a situation. Even when only a part of frames is encrypted and used as the audition data, unnecessary noise is output when the data is reproduced. By preventing this, it is possible to provide more suitable trial listening data.
[0029]
[Means for Solving the Problems]
The data generation method according to the present invention reproduces a data string by outputting a predetermined sound during the reproduction period of the encrypted data frame in the encrypted data frame including the encrypted data representing a part of the input signal. The method further includes an adding step of adding data instructing the data reproducing apparatus, and a generating step of generating a data sequence including an encrypted data frame and a data frame including data representing a part of an input signal. And
[0030]
In the processing of the adding step, data for instructing decryption from the first data frame after the encrypted data frame may be further added.
[0031]
The data instructing decryption from the first data frame can be added to the first encrypted data frame among the plurality of continuous encrypted data frames.
[0032]
The data generation apparatus of the present invention reproduces a data string in an encrypted data frame including encrypted data representing a part of an input signal, by outputting a predetermined sound during a playback period of the encrypted data frame. An additional unit for adding data instructing the data reproducing apparatus, and a generating unit for generating a data sequence including an encrypted data frame and a data frame including data representing a part of an input signal are provided. And
[0033]
According to a first program of the present invention, outputting a predetermined sound in an encrypted data frame including encrypted data representing a part of an input signal during a playback period of the encrypted data frame includes reproducing a data string. And a generating step of generating a data sequence including an encrypted data frame and a data frame including data representing a part of an input signal. Features.
[0034]
In the data reproducing method according to the present invention, a decoding step of decoding an encrypted data frame including encrypted data representing a part of a predetermined signal and a data sequence including a data frame including data representing a part of a predetermined signal If the frame to be decrypted by the decrypting step is an encrypted data frame, the reproducing period of the encrypted data frame includes an output step of outputting a predetermined sound.
[0035]
In the processing in the decrypting step, if the encrypted data frame to be decrypted includes data instructing decryption from the first data frame subsequent to the encrypted data frame, the Decoding can be performed.
[0036]
In the processing in the decoding step, when the decoded data is data representing silence, reproduction based on the decoded data representing silence can be skipped.
[0037]
The data reproducing apparatus of the present invention is a decoding means for decoding an encrypted data frame including encrypted data representing a part of a predetermined signal and a data sequence including a data frame including data representing a part of a predetermined signal. And an output unit for outputting a predetermined sound during a playback period of the encrypted data frame when the frame to be decrypted by the decryption unit is an encrypted data frame.
[0038]
A second program according to the present invention is a decoding program for decoding an encrypted data frame including encrypted data representing a part of a predetermined signal and a data sequence including a data frame including data representing a part of a predetermined signal. In the case where the frame to be decrypted by the processing of the decrypting step is an encrypted data frame, the reproducing period of the encrypted data frame includes an output step of outputting a predetermined sound.
[0039]
According to the data generation method and the data generation device of the present invention, the first program stores a predetermined sound in an encrypted data frame including encrypted data representing a part of an input signal during a reproduction period of the encrypted data frame. Is output to the data reproducing apparatus that reproduces the data sequence, and a data sequence including an encrypted data frame and a data frame including data representing a part of the input signal is generated. You.
[0040]
In the data reproducing method, the data reproducing apparatus, and the second program of the present invention, an encrypted data frame including encrypted data representing a part of a predetermined signal and data representing a part of a predetermined signal are included. When a data sequence composed of data frames is decrypted and the frame to be decrypted is an encrypted data frame, a predetermined sound is output during the playback period of the encrypted data frame.
[0041]
BEST MODE FOR CARRYING OUT THE INVENTION
Embodiments of the present invention will be described below. The correspondence between constituent elements described in the claims and specific examples in the embodiments of the present invention is as follows. This description is for confirming that a specific example supporting the invention described in the claims is described in the embodiment of the invention. Therefore, even if there is a specific example which is described in the embodiment of the invention but is not described here as corresponding to the configuration requirement, the fact that the specific example is It does not mean that it does not correspond to the requirement. Conversely, even if a specific example is described here as corresponding to a configuration requirement, this means that the specific example does not correspond to a configuration requirement other than the configuration requirement. not.
[0042]
The data generation method according to claim 1, wherein the data generation method generates a data sequence (for example, the audio code sequence in FIG. 7) from an input signal, wherein the encryption includes encrypted data representing a part of the input signal. In the encrypted data frame (encrypted frame), outputting a predetermined sound (for example, outputting silence) during the reproduction period of the encrypted data frame is instructed to the data reproducing apparatus that reproduces the data sequence. An adding step (for example, step S9 in FIG. 16) of adding data to be instructed (for example, a silence code string), the encrypted data frame (for example, frame 1 in FIG. 7), and a part of the input signal A generation step (for example, steps S4 and S12 in FIG. 16) for generating the data sequence including a data frame (for example, frame 4 in FIG. 7) including the data to be represented. It is characterized in.
[0043]
In the processing of the adding step of the data generating method according to claim 2, data (for example, the number of skip frames) instructing decryption from the first data frame after the encrypted data frame is further added. It is characterized by.
[0044]
4. The data generation method according to claim 3, wherein the data instructing decryption from the first data frame is added to a first encrypted data frame among a plurality of continuous encrypted data frames. It is characterized by.
[0045]
In the data generation method according to the fourth aspect, the predetermined sound is a silent sound.
[0046]
6. The data generating device according to claim 5, wherein the data generating device generates a data sequence (for example, the audio code sequence in FIG. 7) from the input signal, and the encrypted data includes encrypted data representing a part of the input signal. In the encrypted data frame (encrypted frame), outputting a predetermined sound (for example, outputting silence) during the reproduction period of the encrypted data frame is instructed to the data reproducing apparatus that reproduces the data sequence. An adding unit (for example, a silent code string generating unit 84 in FIG. 6) for adding data to be instructed (for example, a silent code sequence), the encrypted data frame (for example, frame 1 in FIG. 7), and the input signal Generating means (for example, code string selecting means 87 in FIG. 6) for generating the data sequence comprising a data frame (for example, frame 4 in FIG. 7) including data representing a part of And wherein the door.
[0047]
7. The program according to claim 6, wherein the program causes a computer to execute a process of generating a data sequence (for example, the audio code sequence in FIG. 7) from an input signal, and the encrypted data representing a part of the input signal is transmitted to the computer. Outputting a predetermined sound (for example, outputting silence) during the playback period of the encrypted data frame within the encrypted data frame (encryption frame) including the encrypted data frame to the data playback device that plays back the data sequence. An additional step (for example, step S9 in FIG. 16) of adding data (for example, a silence code sequence) to the instruction, the encrypted data frame (for example, frame 1 in FIG. 7), and one of the input signals A generation step (for example, the step shown in FIG. 16) for generating the data sequence including a data frame (for example, frame 4 in FIG. S4, S12) and characterized in that it comprises a.
[0048]
A data reproducing method according to claim 7, wherein a data sequence including an encrypted data frame including encrypted data representing a part of a predetermined signal and a data frame including data representing a part of a predetermined signal is decrypted. If the frame to be decrypted by the decryption step (eg, step S22 in FIG. 17) and the decryption step is the encrypted data frame, a predetermined sound is output during the playback period of the encrypted data frame. And an output step (for example, step S24 in FIG. 17).
[0049]
In the processing in the decryption step of the data reproduction method according to claim 8, the encrypted data frame to be decrypted includes data instructing decryption from the first data frame after the encrypted data frame. , Decoding is performed from the indicated data frame.
[0050]
In the processing in the decoding step of the data reproducing method according to the ninth aspect, when the decoded data is data representing silence, reproduction based on the decoded data representing silence is skipped.
[0051]
The data reproducing apparatus according to claim 10 decodes a data sequence including an encrypted data frame including encrypted data representing a part of a predetermined signal and a data frame including data representing a part of a predetermined signal. (For example, the decryption unit 131 in FIG. 12), and when the frame to be decrypted by the decryption unit is the encrypted data frame, an output for outputting a predetermined sound during the playback period of the encrypted data frame. Means (for example, the decoding means 134 in FIG. 12).
[0052]
12. The program according to claim 11, wherein the program decodes a data sequence including an encrypted data frame including encrypted data representing a part of a predetermined signal and a data frame including data representing a part of a predetermined signal. A step (for example, step S22 in FIG. 17) and an output step of outputting a predetermined sound during a playback period of the encrypted data frame when the frame to be decrypted by the processing of the decrypting step is the encrypted data frame. (For example, step S24 in FIG. 17).
[0053]
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0054]
FIG. 1 is a block diagram illustrating a configuration example of a recording / reproducing apparatus 1 to which the present invention has been applied.
[0055]
In FIG. 1, as a recording medium of the recording / reproducing apparatus 1, for example, a magneto-optical disk 11 driven to rotate by a spindle motor 12 is used. Naturally, it is also possible to use other recording media such as an optical disc and a semiconductor memory, and to record audio data in a format described later on those recording media.
[0056]
When recording data on the magneto-optical disk 11, for example, a so-called magnetic field modulation recording is performed by applying a modulation magnetic field corresponding to the recording data from the magnetic head 14 while irradiating the optical head 13 with laser light. Data is recorded along the recording track of the disk 11. At the time of reproduction, a recording track of the magneto-optical disk 11 is traced by a laser beam by the optical head 13, and magneto-optical reproduction is performed.
[0057]
The optical head 13 includes, for example, a laser light source such as a laser diode, an optical component such as a collimator lens, an objective lens, a polarizing beam splitter, and a cylindrical lens, and a photodetector having a light receiving unit having a predetermined pattern. The optical head 13 is provided at a position facing the magnetic head 14 via the magneto-optical disk 11.
[0058]
The optical head 13 detects the reflected light of the laser beam applied to the target track, detects a focus error by, for example, an astigmatism method, and detects a focus error by a push-pull method generally used in a device that handles a rewritable disk. Detect tracking errors. When reproducing data from the magneto-optical disk 11, the optical head 13 detects a focus error or a tracking error and, at the same time, detects a difference in the polarization angle (Kerr rotation angle) of the laser beam reflected from the target track. To generate a reproduction signal, and output the generated reproduction signal to the RF circuit 15.
[0059]
The RF circuit 15 extracts a focus error signal and a tracking error signal from the output of the optical head 13, supplies them to the servo control circuit 16, binarizes the reproduction signal, and sends the binarized signal to the reproduction system decoder 51. Supply.
[0060]
The servo control circuit 16 includes, for example, a focus servo control circuit, a tracking servo control circuit, a spindle motor servo control circuit, a thread servo control circuit, and the like (all not shown). The focus servo control circuit controls the focus of the optical system of the optical head 13 so that the focus error signal becomes zero. The tracking servo control circuit performs tracking control of the optical head 13 so that the tracking error signal becomes zero. The spindle motor servo control circuit controls the spindle motor 12 to rotate the magneto-optical disk 11 at a predetermined rotation speed (for example, a constant linear speed). The thread servo control circuit moves the optical head 13 and the magnetic head 14 to a target track on the magneto-optical disk 11 specified by the system controller 17. The servo control circuit 16 that performs such various control operations appropriately outputs information indicating the operation state of each unit to the system controller 17.
[0061]
An operation unit 18 and a display unit 19 are connected to the system controller 17. The system controller 17 controls the overall operation of the recording / reproducing apparatus 1 in accordance with operation input information that is supplied when the operation unit 18 is operated by a user and indicates the content of the operation. Further, the system controller 17 manages the traced positions of the optical head 13 and the magnetic head 14 based on the header time read from the recording track of the magneto-optical disk 11 and the address information obtained from the Q data of the subcode. I do.
[0062]
Further, the system controller 17 performs processing such as displaying the reproduction time on the display unit 19. Specifically, the system controller 17 multiplies the address information (absolute time information) obtained from the header time, the Q data of the subcode, and the like by the reciprocal of the data compression ratio (for example, 4 in the case of 1/4 compression). As a result, actual time information is obtained, and this is displayed on the display unit 19 as the reproduction time. At the time of recording, for example, when absolute time information is recorded in advance on a recording track of the magneto-optical disk 11 (pre-formatted), the system controller 17 uses the pre-formatted absolute time information. The current position is displayed at the actual recording time by reading and multiplying by the reciprocal of the data compression ratio.
[0063]
Next, the configuration of the recording system of the recording / reproducing apparatus 1 will be described. Analog audio input signal A input from input terminal 31 _in Is supplied to an A / D (Analog / Digital) converter 33 via a low-pass filter 32, and is quantized by the A / D converter 33. The digital audio signal obtained by the A / D converter 33 is supplied to an ATC (Adaptive Transform Coding) encoder 36 (hereinafter, appropriately referred to as the encoder 36). On the other hand, the digital audio input signal D input from the input terminal 34 _in Is supplied to the encoder 36 via the digital input interface circuit 35.
[0064]
The encoder 36 performs data compression on the digital audio signal supplied from the A / D converter 33 in accordance with a predetermined compression rate, and outputs the obtained compressed data to a RAM (Random Access Memory) 37. For example, assuming that the data compression rate is 1/8, the data transfer rate here is 1/8 (9.375 sectors / second) of the data transfer rate (75 sectors / second) of the standard CD-DA format. Reduced.
[0065]
The RAM 37 writes data supplied from the encoder 36 and reads data from the encoder 38 under the control of the system controller 17. That is, the RAM 37 is used as a buffer memory for temporarily storing data supplied from the encoder 36 and recording the data on a disk as needed. As described above, since the data input to the RAM 37 is compressed to 1/8, it is sufficient to record one sector for the data before compression of eight sectors. Since every other recording is practically impossible, recording is performed in a continuous sector (cluster unit).
[0066]
This recording is performed at the same data transfer rate (75 sectors / second) as in the standard CD-DA format by using a cluster composed of a predetermined plurality of sectors (for example, 32 sectors + several sectors) as a recording unit through a pause period. Performed in bursts. That is, in the RAM 37, data (output of the encoder 36) for eight sectors, which is continuously written at a low transfer rate of 9.375 (= 75/8) sectors / second corresponding to the bit compression rate described above, is written. The data is collectively read out by the encoder 38 as recording data at a transfer rate of 75 sectors / sec and recorded on the magneto-optical disk 11. Therefore, when the disk rotation speed is the same speed (constant linear speed) as the standard CD-DA format, the same recording density and storage pattern as those in the CD-DA format are recorded.
[0067]
The audio data burst-read from the RAM 37, that is, the recording data, is supplied to the encoder 38. Here, as a unit of continuous recording in one recording, for example, a cluster composed of 32 sectors and several sectors for cluster connection arranged before and after the cluster are set as one recording unit. By setting the cluster connection sector to be longer than the interleave length in the encoder 38, even if the interleave occurs, it does not affect the recording of data of other clusters.
[0068]
The encoder 38 performs a parity addition process for error correction, an interleave process, an EFM (Eight to Fourteen Modulation) encoding process, and the like on the recording data supplied from the RAM 37. The recording data obtained by performing such processing is supplied to the magnetic head drive circuit 39.
[0069]
Next, the configuration of the reproducing system of the recording / reproducing apparatus 1 will be described. The decoder 51 performs decoding processing for error correction, EFM decoding processing, and the like on the reproduced signal that has been binarized and supplied by the RF circuit 15, and converts, for example, ATC audio data with a data compression ratio of １ ／, Playback is performed at a transfer rate of 75 sectors / sec, which is faster than the regular transfer rate. The reproduction data obtained by the decoder 51 is supplied to the RAM 52.
[0070]
The RAM 52 writes data from the decoder 51 and reads data from the ATC decoder 53 under the control of the system controller 17. For example, reproduction data supplied from the decoder 71 at a transfer rate of 75 sectors / second is written to the RAM 52. The RAM 52 continuously outputs the written reproduction data to the ATC decoder 53 (hereinafter, appropriately referred to as a decoder 53) at a transfer rate of 9.375 (= 75/8) sectors / second. That is, the decoder 53 processes data having a data compression rate of 1/8, which corresponds to the encoder 36 described above.
[0071]
The decoder 53 reproduces 16-bit digital audio data by, for example, expanding the data by 8 times (bit expansion). The digital audio data reproduced by the decoder 53 is supplied to a D / A (Digital / Analog) converter 54.
[0072]
The D / A converter 54 converts the digital audio data supplied from the decoder 53 into an analog signal and outputs the analog audio output signal A _OUT Is output to the output terminal 56 via the low-pass filter 55.
[0073]
The system controller 17 includes, for example, a wireless communication function with an external device, an encryption function, a decryption function of encrypted data, a function of acquiring and retaining key information, an authentication function, and the like. It has each function. It is desirable from the viewpoint of data security that these functions are incorporated as one-chip circuits in the system controller 17.
[0074]
Here, data (code sequence) processed in the recording / reproducing apparatus 1 will be described.
[0075]
FIG. 2 is a diagram illustrating an example of a frame of an audio code string processed by the recording / reproducing apparatus 1.
[0076]
In this example, at the beginning of each frame (frame N), there is a fixed-length header including a synchronization signal, and this header includes, in addition to the synchronization signal, the number of encoding units (codes) of the audio signal included in the frame. Number of conversion units) is described. As will be described later, the encoding unit is, for example, a set of spectral signals to be encoded, divided into eight bands.
[0077]
Following the header, quantization precision data, normalization coefficient data, and spectrum coefficient data are recorded according to the number of coding units and spectra. When the length of each frame is fixed, an empty area is appropriately formed after the spectral coefficient data according to the data amount of the header, quantization precision data, normalization coefficient data, spectrum coefficient data, and the like.
[0078]
The number of coding units of the frame N shown in FIG. 2 is set to a value other than 0, and the code string described after the header is not encrypted. In the band specified by the number of coding units, reproduction of an audio code string based on quantization accuracy data, normalization coefficient data, and spectrum coefficient data is performed.
[0079]
FIG. 3 is a diagram illustrating another example of a frame processed by the recording / reproducing apparatus 1.
[0080]
In FIG. 3, the value of the number of coding units described in the header 1 of the frame N is 0, and the encryption flag = 1 is described after the header 1. The encryption flag = 1 indicates that the subsequent code string in the frame N has been encrypted. Hereinafter, a frame partially including an encrypted code string, such as the frame N in FIG. 3, is referred to as an encrypted frame as appropriate.
[0081]
In the example of FIG. 3, the header 2 describing the synchronization signal 2 and the number of encoding units 2 (≠ 0), quantization precision data, normalization coefficient data, and spectrum coefficient data are encrypted. . Therefore, the reproducing apparatus that has obtained the code string in FIG. 3 cannot correctly reproduce the encrypted part unless it obtains the encryption / decryption key for decrypting the encryption.
[0082]
The decoder (for example, the decoder 53) that reproduces the encrypted frame reads the value 0 of the number of coding units, recognizes that the frame contains a silent code string having a bandwidth of 0 Hz, and performs encryption. A silent PCM signal is generated during the frame playback period without playing back the encrypted code string after the encryption flag. That is, in this example, depending on the value of the number of encoding units, during playback of an encrypted frame, silence is output (whether no sound is output) or a code string after the encryption flag is decoded. It is specified whether to output sound.
[0083]
Thereby, it is possible to prevent the encrypted code string from being reproduced as a normal audio code string (unencrypted audio code string). That is, the noise generated when the encrypted code string is reproduced is not output.
[0084]
During the playback of the encrypted frame, information specifying whether to output a silent sound or to output a sound obtained by decoding a code string after the encryption flag (designating that the frame is an encrypted frame). As information, instead of being specified by the value of the number of coding units, a code string of a predetermined pattern that actually outputs silence may be described after the header.
[0085]
FIG. 4 is a diagram illustrating an example of a frame in which a silence code string (silence data) of a predetermined pattern for outputting silence is described after a header.
[0086]
Since the silence code string is described in the frame N of FIG. 4, the decoder 53 does not reproduce the encrypted code string described after the encryption flag during the reproduction period of the frame N without reproducing the encrypted code string. Continue outputting silence based on the code string.
[0087]
FIG. 5 is a diagram illustrating another example of a frame when an encryption flag is used as information specifying that the frame is an encrypted frame.
[0088]
When the encryption flag = 0 is described as shown in FIG. 5, the decoder 53 recognizes that the frame N is an encrypted frame (the code string after the encryption flag is actually encrypted). However, it is recognized that it is a mere silence code sequence), and silence is continuously output during the reproduction period of the frame N.
[0089]
The value of the encryption flag is rewritten when the user obtains the encryption / decryption key by downloading it from a predetermined server or the like. Therefore, when the encryption / decryption key is obtained, the value of the encryption flag is rewritten to 1, and thereafter, the code string after the encryption flag is recognized by the decoder 53 as an encrypted code string. become.
[0090]
As described above, various information can be used as information for specifying that the frame is an encrypted frame.
[0091]
Note that it is preferable to use, as the information, information having a minimum data amount among information permitted in a format, such as a restriction by a frame length. That is, by using the information of the minimum data amount as the information designating that the frame is an encrypted frame, the area for recording the encrypted code string (for example, the code string after the encryption flag in FIG. 3) is widened. Can be secured. Further, the information designating that this is an encrypted frame is not limited to the above-described position, but may be described at any position in the frame.
[0092]
FIG. 6 is a block diagram illustrating a detailed configuration example of the encoder 36 in FIG.
[0093]
Here, as shown in FIG. 4, an example of the configuration of the encoder 36 that describes a silence code string of a specific pattern as information designating that the frame is an encrypted frame during a frame reproduction period is shown.
[0094]
The audio signal supplied from the A / D converter 33 in FIG. 1 is input to an encoding unit 81 and an encoding unit 82, and each of them is subjected to high-efficiency encoding.
[0095]
The encoding means 82 uses a predetermined number of bits that is equal to or less than the total number of bits of the frame minus the number of bits required to record the silent code string and the encryption flag (assigned to the signal). ) Perform encoding. On the other hand, the encoding means 81 performs encoding using a predetermined number of bits equal to or less than the total number of bits of the frame.
[0096]
The code string obtained by the coding means 81 is output to the code string selection means 87, and the code string obtained by the coding means 82 is output to the code string encryption means 83.
[0097]
Note that the formed free area is filled with bits having a value different from the encryption flag. For example, as shown in FIG. 3, when the encrypted code string is described next to the encryption flag, the encryption flag is set to 1 and the value 0 is described in the empty area.
[0098]
The code string encrypting means 83 encrypts the output from the coding means 82 by using, for example, an encryption key supplied from the system controller 17 in FIG. 1, and converts the encrypted code string into a code string combining means 86. Output to
[0099]
The silence code string generating means 84 generates a silence code string of a predetermined pattern that generates silence when decoded, and outputs the silence code string to the encryption flag adding means 85.
[0100]
The encryption flag adding means 85 adds an encryption flag indicating that the subsequent code string is encrypted to the end of the silent code string generated by the silent code string generating means 84, and obtains the obtained code string. Is output to the code string synthesizing means 86. Therefore, the code string output from the encryption flag adding means 85 to the code string synthesizing means 86 corresponds to, for example, the silent code string and the encryption flag = 1 in FIG.
[0101]
The code string synthesizing means 86 adds the encrypted code string supplied from the code string encrypting means 83 to the end of the code string supplied from the encryption flag adding means 85. Generate all N. The header 1 in FIG. 4 is added at a predetermined timing. The code string (for example, frame N in FIG. 4) generated by the code string combining means 86 is output to the code string selecting means 87.
[0102]
The code string selecting means 87 receives the frame (encrypted code) supplied from the encoding means 81 in accordance with information supplied from the system controller 17 of FIG. 1 and specifying whether or not the frame is to be an encrypted frame. (A frame not including a sequence) and an encrypted frame supplied from the code sequence synthesizing means 86, and output to the subsequent stage. That is, when it is specified that an encoded frame is to be used, the code string selecting means 87 selects the code string supplied from the code string synthesizing means 86 and outputs the selected code string to the outside. If so, the code string supplied from the encoding means 81 is selected and output to the outside.
[0103]
Accordingly, a frame not including the encrypted code string as shown in FIG. 2 or a cipher including a silent code string and partially including the encrypted code string as shown in FIG. The encoded frame is output from the code string selecting means 87 to the RAM 37 in FIG.
[0104]
In the RAM 37, the output from the encoder 36 is buffered, and the above-described predetermined unit code string is output as recording data to the subsequent encoder 38 and recorded on the magneto-optical disk 11.
[0105]
FIG. 7 is a diagram illustrating an example of a frame sequence output from the encoder 36. In FIG. 7, the reproduction direction is from left to right in the figure, and the header, encryption flag, and the like of each frame described above are omitted for convenience of description.
[0106]
In FIG. 7, the area of the encrypted code string is indicated by oblique lines, and frames 1 to 3 and frames 7 to 9 are cipher codes in which a silent code string and an encrypted code string are described. It is a chemical frame. Frames 4 to 6 are frames in which an unencrypted audio code string is described.
[0107]
Therefore, when the audio code string composed of such a frame string is used as a code string for trial listening, the user can listen to the frames 4 to 6 even without acquiring the encryption / decryption key.
[0108]
That is, when the audio code string of FIG. 7 is reproduced, during the reproduction period of frames 1 to 3, silence is output (no sound is output) based on the silence code string described respectively, and frames 4 to 6 are output. During the reproduction period of, a sound obtained by reproducing the audio code string is output. Further, during the reproduction period of frames 7 to 9, silence is output based on the silence code strings described in each of them.
[0109]
As described above, even when frames 1 to 3, which are encrypted frames, are reproduced, for example, the sound obtained when the encrypted code string is reproduced, that is, noise is not output. The business operator can generate a trial code sequence such that only the sound of a predetermined frame can be previewed without generating noise, and can distribute it to users.
[0110]
In addition, the user pays a predetermined fee when he / she wants to listen to the trial code sequence and purchase the content (when the user wants to listen to the entire content by decoding the encrypted code sequence included in the encrypted frame). For example, since only the encryption / decryption key needs to be obtained, the communication time can be reduced as compared with the case where the entire content is downloaded.
[0111]
Next, details of the configuration in FIG. 6 will be described.
[0112]
FIG. 8 is a block diagram showing a configuration example of the encoding unit 81 of FIG. The encoding means 82 has the same configuration as that shown in FIG.
[0113]
Here, a case where high efficiency coding is performed by receiving a digital signal such as an audio PCM signal and performing band division coding (SBC), adaptive conversion coding (ATC), and adaptive bit allocation will be described. I do. Adaptive transform coding is a coding method that adapts bit allocation based on a discrete cosine transform (DCT) or the like, and converts an input signal into a spectral signal for each time block, and for each predetermined band, The spectral signals are collectively normalized, that is, each signal component is divided by a normalization coefficient approximating the maximum signal component, and then quantized and encoded with a quantization accuracy determined in a timely manner according to the properties of the signal. .
[0114]
The conversion unit 101 receives the input of the acoustic waveform signal, converts the signal into a signal frequency component, and outputs the signal frequency component to the signal component encoding unit 102. The signal component encoding unit 102 encodes the input signal frequency component and outputs the encoded signal frequency component to the code sequence generation unit 103. The code sequence generation unit 103 generates a code sequence from the signal frequency components encoded by the signal component encoding unit 102, and outputs the generated code sequence to the code sequence selection unit 87.
[0115]
FIG. 9 is a block diagram showing a more detailed configuration example of the conversion means 101 of FIG.
[0116]
The acoustic waveform signal input to the conversion unit 101 is divided into two bands by the band division filter 111, and each signal is output to the forward spectrum conversion units 112-1 and 112-2. The forward spectrum transform means 112-1 and 112-2 convert the input signal into a spectrum signal component using, for example, MDCT or the like and output the signal to the signal component encoding means 102. The signals input to the forward spectrum conversion means 112-1 and 112-2 are の of the bandwidth of the signal input to the band division filter 111, and the signal inputs are also decimated to そ れ ぞ れ, respectively. ing.
[0117]
In the conversion means 101 of FIG. 9, the signal divided into two bands by the band division filter 111 is converted into a spectrum signal component using MDCT, but the input signal is converted into a spectrum signal component. Any method may be used as the method of converting to. For example, the input signal may be converted into a spectrum signal component by MDCT without band division, or the input signal may be converted into a spectrum signal by DCT or DFT.
[0118]
By using a so-called band division filter, it is possible to divide an input signal into band components. However, MDCT, DCT, or It is preferable to perform spectrum conversion using DFT.
[0119]
In FIG. 9, the input acoustic waveform signal is divided into two bands by the band division filter 111, but the number of band divisions does not have to be two. Information indicating the number of band divisions in the band division filter 111 is output to the code sequence generation unit 103 via the signal component encoding unit 102.
[0120]
FIG. 10 is a diagram in which the absolute value of the spectrum signal by MDCT obtained by the conversion unit 101 is converted into a power level.
[0121]
The acoustic waveform signal input to the conversion means 101 is converted into, for example, 64 spectral signals for each predetermined time block. These spectrum signals are divided into eight bands [1] to [8] by the signal component encoding means 102, for example, as shown by eight frames surrounded by solid lines in the figure. , Quantization and normalization are performed for each band. A set of spectral signals divided into these eight bands, that is, a set of spectral signals to be quantized and normalized is an encoding unit.
[0122]
By changing the quantization precision for each coding unit based on the distribution of frequency components, efficient coding that minimizes deterioration of the quality of sound audible to humans becomes possible.
[0123]
FIG. 11 is a block diagram showing a detailed configuration example of the signal component encoding unit 102 in FIG.
[0124]
Here, for example, the signal component encoding unit 102 separates, from the input spectrum signal, a tone portion that is particularly important in terms of audibility, that is, a signal component in which energy is concentrated around a specific frequency. May be encoded separately from the spectral components (non-tone components), or may be encoded without separation.
[0125]
The normalization unit 121 receives a spectral signal of a tone component or a non-tone component for each encoding unit, performs normalization, and outputs the result to the quantization unit 123. The quantization accuracy determination unit 122 calculates the quantization accuracy with reference to the input coding unit, and outputs the calculation result to the quantization unit 123. The quantization precision determining means 122 determines the quantization precision such that when the input coding unit is a tone component, the quantization precision is higher than when the input coding unit is a non-tone component. The quantization means 123 quantizes the normalization result input from the normalization means 121 with the quantization precision determined by the quantization precision determination means 122, generates a code, and adds the code to the generated code. And encoding information such as normalization coefficient information and quantization accuracy information.
[0126]
Further, the signal component encoding means 102 also encodes the position information of the tone component and the like together with the tone component and outputs the encoded information.
[0127]
FIG. 12 is a block diagram showing a configuration example of the decoder 53 of FIG.
[0128]
The decryption unit 131 converts the code string (frame) supplied from the RAM 52 into a PCM signal, and determines whether the supplied frame is an encrypted frame. When determining that the supplied frame is not an encrypted frame, the decryption unit 131 outputs the decryption result to the signal selection unit 135.
[0129]
In this case, the output of the decoding unit 131 is selected by the signal selection unit 135 and output to the outside, and the user can listen to the reproduction result of the audio code string.
[0130]
When the decryption means 131 determines that the encryption flag described in the supplied frame is 0 and outputs a code string included in the frame after the encryption flag as a silent signal, the decryption unit 131 converts the silent PCM signal into a silent signal. In addition to outputting to the signal selection means 135, the encryption flag = 0 and the encrypted code string are output to the encryption flag inspection means 132.
[0131]
In this case, as will be described later, a selection signal representing 0 is input from the encryption flag checking unit 132 to the signal selecting unit 135, and the output of the decrypting unit 131 is selected by the signal selecting unit 135. Output (no sound is output).
[0132]
If the decoding unit 131 determines that the supplied frame is, for example, an encrypted frame including a silence code string as shown in FIG. 4, the decoding unit 131 converts the silence PCM signal, which is the result of decoding the silence code string, into a frame. The signal is output to the signal selection means 135, and the subsequent code string is output to the encryption flag inspection means 132. Therefore, the encryption flag = 1 in FIG. 4 and the encrypted code string are output to the encryption flag checking unit 132.
[0133]
The encryption flag checking unit 132 checks whether the value of the encryption flag, which is the first bit supplied from the decoding unit 131, is 1. When determining that the value of the encryption flag is 1, the encryption flag checking unit 132 outputs a selection signal indicating 1 to the signal selection unit 135, and when determining that the value of the encryption flag is 0, A selection signal representing 0 is output to the signal selection means 135. Further, the encryption flag inspection unit 132 outputs the encrypted code string after the encryption flag to the encryption / decryption unit 133.
[0134]
The encryption / decryption unit 133 decrypts the code string supplied from the encryption flag inspection unit 132 using the encryption / decryption key supplied from the system controller 17, and outputs the obtained decryption result to the decryption unit 134. When the user has not purchased an encryption / decryption key and the encryption / decryption key is not supplied from the system controller 17, the encryption / decryption unit 133 encrypts the code string supplied from the encryption flag inspection unit 132. The data is output to the decoding means 134 as it is.
[0135]
When the decoding result obtained by decoding the encrypted code string is supplied from the encryption / decryption means 133, the decoding means 134 decodes (reproduces) the code string and converts the obtained PCM signal into a signal selected by the signal selecting section. Output to the means 135. In addition, when a code string that has been encrypted is supplied from the encryption / decryption means 133, the decoding means 134 outputs a silent PCM signal to the signal selection means 135 without decoding the code string.
[0136]
When the value of the encryption flag is 1, the output of the decryption means 134 is selected based on the selection signal supplied from the encryption flag inspection means 132 and output to the outside. Therefore, when the value of the encryption flag is 1, either a PCM signal obtained by reproducing the decoding result of the encrypted code string or a silent PCM signal generated by the decoding unit 134 is output.
[0137]
When the value of the selection signal supplied from the encryption flag inspection unit 132 is 1, the signal selection unit 135 outputs the PCM signal supplied from the decryption unit 134 to the external D / A converter 54 (FIG. 1). On the other hand, when the value of the selection signal is 0, the PCM signal supplied from the decoding unit 131 is output to the D / A converter 54.
[0138]
Next, details of the configuration in FIG. 12 will be described.
[0139]
FIG. 13 is a block diagram illustrating a configuration example of the decoding unit 131 in FIG.
[0140]
The code string decomposing means 151 receives the input of the frame, decomposes the code string, extracts the code of each signal component, and outputs the obtained code to the signal component decoding means 152. The signal component decoding unit 152 decodes the input encoded frame, and outputs the decoding result to the inverse transform unit 153.
[0141]
FIG. 14 is a block diagram showing a detailed configuration example of the signal component decoding means 152.
[0142]
The inverse quantization means 161 inversely quantizes the input code and outputs the result to the inverse normalization means 162. The inverse normalizing means 162 inversely normalizes the input code. That is, decoding processing is performed by the inverse quantization means 161 and the inverse normalization means 162, and a spectrum signal is output.
[0143]
FIG. 15 is a block diagram showing a detailed configuration example of the inverse conversion means 153 of FIG.
[0144]
In the example of FIG. 15, the spectrum signal decoded by the signal component decoding unit 152 is separated into two bands by the inverse conversion unit 153 and input to the inverse spectrum conversion units 171-1 and 172-2. I have.
[0145]
The inverse spectrum conversion means 171-1 and 171-2 perform inverse spectrum conversion on the input spectrum signal, and output the obtained signal of each band to the band synthesis filter 172. The band combining filter 172 combines the input signals of the respective bands and outputs the combined signal.
[0146]
The PCM signal output from the band synthesis filter 172 is output to the signal selection unit 135 in FIG.
[0147]
Next, with reference to a flowchart of FIG. 16, a process of encoding by software and recording the generated audio code string on the magneto-optical disk 11 of FIG. 1 will be described.
[0148]
Here, a case will be described in which an audio code string is generated by software. However, the same processing is naturally performed by hardware having the above-described configurations to generate an audio code string.
[0149]
In step S1, 1 is set to a variable J representing the number of the frame to be encoded, and the process proceeds to step S2. In step S2, whether or not the frame is an encrypted frame is determined based on the value of the variable J. That is, information specifying an encrypted frame (information specifying which frame is not to be previewed as shown in FIG. 7) is determined and input by, for example, an administrator.
[0150]
If it is determined in step S2 that the current frame to be encoded is not an encrypted frame, the process proceeds to step S3, where the input audio signal is encoded by the codec, and the process proceeds to step S4. In step S4, recording of the audio signal encoded in step S3 (description of quantization coefficient data, normalization coefficient data, spectrum coefficient data, and the like on the magneto-optical disk 11) is performed.
[0151]
In step S5, the value 0 is recorded in all the empty areas formed in the frame, and the process proceeds to step S6, where it is determined whether the processed frame is the last frame. Thereby, for example, a frame that does not include the encrypted data as shown in FIG. 2 is generated and recorded on the magneto-optical disk 11.
[0152]
If it is determined in step S6 that the processed frame is not the last frame, the process proceeds to step S7, and after the value of the variable J is increased by 1, the process returns to step S2, and the subsequent processes are repeated.
[0153]
On the other hand, if it is determined in step S2 that the encoding target frame is to be an encrypted frame, the process proceeds to step S8, in which a silent code sequence having a specific pattern is generated which instructs to output silence during the reproduction period. , Are encoded.
[0154]
The generated silence code string is recorded in step S9, and proceeds to step S10. In step S10, the encryption flag = 1 is recorded following the silent code string.
[0155]
In step S11, the input audio signal is encoded by the codec, and the process proceeds to step S12, where encryption is performed. Also, the encrypted input audio signal is recorded following the encryption flag added in step S10. Thereby, for example, a frame as shown in FIG. 4 is generated and recorded on the magneto-optical disk 11.
[0156]
Thereafter, the process proceeds to step S6, and the subsequent processes are repeated. If it is determined in step S6 that the processed frame is the last frame, the process ends.
[0157]
By the above processing, for example, as shown in FIG. 7, an encrypted frame including a silence code string and an encrypted code string, or a frame string including a frame including an original audio code string is converted to the magneto-optical disk 11. Recorded in. Note that the audio code string generated as described above may be distributed as a preview code string via a network.
[0158]
Next, with reference to a flowchart of FIG. 17, a description will be given of a process of software for reproducing the audio code string generated by the process of FIG.
[0159]
In step S21, 1 is set to a variable J representing the number of the frame to be decoded, and the process proceeds to step S22. In step S22, the frame to be decrypted is decrypted, and the flow advances to step S23 to determine whether the decrypted frame is an encrypted frame.
[0160]
If it is determined in step S23 that the decrypted frame is not an encrypted frame, the process proceeds to step S24, where the audio signal (PCM signal) decrypted in step S22 is reproduced. Therefore, when the frame to be decrypted is a frame that can be previewed (a frame that does not include encrypted data), a preview sound that is the decryption result is output.
[0161]
In step S25, it is determined whether or not the processed frame is the last frame. If it is determined that the processed frame is not the last frame, the process proceeds to step S26. After the value of the variable J is increased by 1, the process returns to step S22. Subsequent processing is repeated.
[0162]
On the other hand, if it is determined in step S23 that the decrypted frame is an encrypted frame, the process proceeds to step S27, where it is determined whether the encryption flag is 1.
[0163]
If it is determined in step S27 that the value of the encryption flag is not 1, the process proceeds to step S24, and the audio signal decoded in step S22 is reproduced. As described above, if the value of the encryption flag is not 1, that is, if it is 0, even if the encrypted code string is actually in the frame, in step S22, the encrypted code The sequence is not reproduced, and the silence code sequence is reproduced. Therefore, in the process of step S24 performed after the determination of step S27, a silent PCM signal is reproduced.
[0164]
If it is determined in step S27 that the value of the encryption flag is 1, the process proceeds to step S28, where the encrypted audio code string described after the encryption flag is written using the encryption / decryption key. After decoding, the process proceeds to step S29, where the high-efficiency code of the obtained code string is decoded.
[0165]
In step S30, the audio signal decoded in step S29 is reproduced, the process proceeds to step S25, and the subsequent processes are repeated. If it is determined in step S25 that the reproduced frame is the last frame, the process ends.
[0166]
In the above description, the case where the audio code string is reproduced and output is described. Next, the decoding of the encrypted frame is appropriately performed in the same manner, and the audio code string that can be previewed in all the frames is generated. Subsequently, a configuration for recording the data on a predetermined recording medium and a process will be described.
[0167]
FIG. 18 illustrates a recording apparatus that receives an input of an audio code string generated by the process described with reference to FIG. 16, decodes an encrypted frame, and records the decoded audio code string on a predetermined recording medium. FIG. 3 is a block diagram illustrating a configuration example. 18, the same components as those in FIG. 12 are denoted by the same reference numerals, and description thereof will be omitted as appropriate.
[0168]
The code string selecting means 181 outputs to the recording means 182 any one of the audio code string supplied from the outside and the code string supplied by the encryption / decryption by the encryption / decryption means 133. As described above, when the value of the encryption flag is 1, a selection signal representing 1 is supplied from the encryption flag inspection unit 132, and thus the code string selection unit 181 is supplied from the encryption / decryption unit 133. A code string obtained by decrypting the encryption is selected and output to the recording means 182.
[0169]
On the other hand, when the value of the encryption flag is 0, since a selection signal representing 0 is supplied from the encryption flag checking unit 132, the code sequence selection unit 181 selects a code sequence supplied from the outside, and Is output to the recording means 182. Note that, for example, when the processing by the recording device in FIG. 18 is performed after the encryption / decryption key is obtained, the code string supplied from the outside is already rewritten so that the value of the encryption flag becomes 1. Is not recorded as it is.
[0170]
The recording unit 182 records the code string supplied from the code string selection unit 181 on a recording medium (not shown). For example, when a frame not subjected to encryption as shown in FIG. 2 is input to the code string selecting means 181, the code string is selected by the code string selecting means 181, and a predetermined recording medium is recorded by the recording means 182. Recorded in. When an encrypted frame as shown in FIG. 4 is input, the encrypted code string is decrypted by the encryption / decryption means 133, and the code string resulting from the decryption is selected by the code string selection means 181 and recorded. The information is recorded on the recording medium by the means 182.
[0171]
Next, with reference to a flowchart of FIG. 19, a description will be given of a process of software that decodes an encrypted code string included in an encrypted frame and records the obtained audio code string on a recording medium.
[0172]
Here, a case where the processing is performed by software will be described, but the same processing is naturally performed by hardware having a configuration as illustrated in FIG. 18.
[0173]
In step S41, 1 is set to a variable J indicating the number of the frame to be recorded, and the process proceeds to step S42. In step S42, the frame to be recorded is decrypted, and the process advances to step S43 to determine whether the decrypted frame is an encrypted frame.
[0174]
If it is determined in step S43 that the decrypted frame is not an encrypted frame, the process proceeds to step S44, and the code string supplied as a recording target is recorded on the recording medium as it is.
[0175]
In step S45, it is determined whether or not the recorded frame is the last frame. If it is determined that the frame is not the last frame, the process proceeds to step S46, and after the value of the variable J is increased by 1, the process returns to step S42. , And the subsequent processes are repeated.
[0176]
On the other hand, when it is determined in step S43 that the decrypted frame is an encrypted frame, the process proceeds to step S47, and it is determined whether the value of the encryption flag is 1.
[0177]
If it is determined in step S47 that the value of the encryption flag is not 1, the process proceeds to step S44, and the silent code string decoded in step S42 is recorded.
[0178]
If it is determined in step S47 that the value of the encryption flag is 1, the process proceeds to step S48, where the encrypted audio code string described next to the encryption flag is decrypted using the decryption key. Is done. In step S49, the code string obtained by decoding is recorded from the beginning of the recording position allocated to the frame being processed at this time.
[0179]
In step S50, the value 0 is described in all of the empty areas, the process proceeds to step S45, and the subsequent processing is repeatedly executed. If it is determined in step S45 that the recorded frame is the last frame, the process ends.
[0180]
As described above, the encrypted code string is appropriately decoded, and the audio code string obtained by decoding the entire code string is recorded on the recording medium. It should be noted that a recording medium on which an audio code string to be processed as described above is recorded (a recording medium on which an audio code string before processing is recorded) is obtained by decoding by the above processing. The recording medium on which the audio code string as the decoding result is recorded (the recording medium on which the processed audio code string is recorded) may be the same recording medium or different recording media.
[0181]
In the above, the case where the encrypted code string is identified by the encryption flag has been described. However, when a silent frame (a frame having no sound even when reproduced) is originally encrypted, the encryption is performed. Without using a flag, the silence code string is encrypted, and immediately after the silence code string (generated at the time of creating the audio code string and included in the frame) immediately after the silence code string described after the header of each frame. May be arranged at
[0182]
In this case, even if the encrypted code string is played back by a decoder that cannot decode the code string, as described above, it is a silent signal that is played back with the encrypted frame, and the unencrypted frame is played back. Is an original audio signal (silence signal). Therefore, even if the frame is encrypted, no noise is output when the frame is reproduced.
[0183]
FIG. 20 shows an example of such an audio code string. In FIG. 20, the value of the number of encoding units is set to 0 instead of recording silence data, thereby designating that frame N in FIG. 20 is an encrypted frame.
[0184]
In the above description, since silence is output during the playback period of the encrypted frame, for example, as shown in FIG. 21, when the trial listening portion is located at a remote place, the first trial listening portion (frame 3) is output. The user must continue to listen to the silence from the time point 5) to the second audition portion (frames 9 to 12) (while the silence of the frames 6 to 7 is reproduced). Therefore, in order to avoid this and allow only the trial listening part to be heard continuously, information specifying the position of the next trial listening part is described in the frame, and the trial listening is performed based on the information. The reproduction of the code string may be controlled.
[0185]
FIG. 22 is a diagram illustrating an example of a frame including information for specifying the position of the next trial listening possible portion. The description of the above-described components will be omitted as appropriate.
[0186]
In FIG. 22, the number of coding units of the header 1 is 0, and as described above, the decoder reads the value of the number of coding units 0, and this frame is a silent code sequence having a bandwidth of 0 Hz. Is interpreted as recorded, and a silent signal is generated during the reproduction period of this frame.
[0187]
Immediately after the header 1, a type flag indicating the type of this frame is described. Further, immediately after the header 1, a silent code string may be actually recorded as shown in FIG. 4, and the type flag may be described immediately after that.
[0188]
Hereinafter, in a frame that does not include an encrypted code string, 0 is written in a free area (an area where a type flag is written in an encrypted frame). Also, for example, as in frames 1 and 2 in FIG. 21, the first encrypted frame in a frame sequence including a plurality of encrypted frames, that is, frame 1 has 2 as a type flag, and other frames have That is, 1 is described as the type flag in frame 2.
[0189]
As shown in the frame 2 of FIG. 22, the number of dummy skip frames is described after the type flag 1, which is described when the type flag is 2 and is equal to or smaller than the number of skip frames. The allocation bits are adjusted so as to be equal for each frame, and this area does not have to be provided.
[0190]
The decoder determines that an encrypted code string is recorded after the type flag in which 1 or 2 is set and the number of skip frames following the type flag.
[0191]
On the other hand, as will be described in detail later, after recording the silent code string, the encoder records the type flag 2 and then records the number of skipped frames, and then encrypts and records the encoded audio signal. Further, after recording the silent code string, the encoder records the type flag 1 and then records a dummy code, and then encrypts and records the encoded audio signal.
[0192]
FIG. 23 is a block diagram illustrating a configuration example of the encoder 36 that records the type flag and the number of skip frames as necessary. The same components as those in FIG. 6 are denoted by the same reference numerals.
[0193]
The encoding unit 81 and the encoding unit 82 encode the supplied audio signal with high efficiency. At this time, the encoding unit 82 determines the predetermined number of bits equal to or less than the number obtained by subtracting the number of bits necessary for encoding the silence code sequence, the type flag, and the number of skipped frames from the total number of bits of the frame. To perform encoding. The encoding unit 81 performs encoding using a predetermined number of bits equal to or less than the total number of bits of the frame.
[0194]
The code string encrypting means 83 encrypts the output from the coding means 82 using an encryption key supplied from the system controller 17 and outputs the encrypted code string to the code string synthesizing means 86. .
[0195]
The silent code string generating means 84 generates a silent code string and outputs the code string to the type flag adding means 201.
[0196]
The type flag adding unit 201 adds, after the silent code sequence generated by the silent code sequence generating unit 84, a type flag = 1 indicating that a code sequence thereafter is encrypted, and the number of dummy skip frames. Then, the obtained code string is output to the code string combining means 86. Therefore, the code string output from the type flag adding means 201 to the code string synthesizing means 86 includes the silent code string of frame 2 (the number of coding units = 0 or the actual silent code string) shown in FIG. = 1 and an empty area (the number of dummy skip frames).
[0197]
The code string synthesizing means 86 adds the code string supplied from the code string encrypting means 83 to the end of the code string supplied from the type flag adding means 201, and generates, for example, the entire frame 2 in FIG. The code string generated by the code string combining means 86 is output to the code string selecting means 205.
[0198]
The silent code string generating means 202 generates a silent code string, and outputs the code string to the type flag / skip frame number information adding means 203.
[0199]
The type flag / skip frame number information adding means 203 indicates that a code string after the silent code string generated by the silent code string generating means 202 is encrypted, , The type flag = 2 indicating that the frame is the first frame and the number of skipped frames are added, and the obtained code sequence is output to the code sequence synthesizing unit 204. Since the information for specifying the skip frame number is supplied from the system controller 17, the type flag / skip frame number information adding unit 203 describes the skip frame number according to the specification.
[0200]
For example, it is preferable that the number of skip frames described is a number from the start frame of the next previewable portion to a frame that is several seconds earlier in reproduction time. Thereby, for example, after the first trial listening portion (frames 3 to 5) in FIG. 21 is reproduced, before the reproduction of the second trial listening portion (frames 9 to 12) is started, only a few seconds. Since silence is output, the user who is listening can know that the listening interval has been switched.
[0201]
The code string output from the type flag / skip frame number information adding means 203 to the code string synthesizing means 204 is a silent code string of frame 1 shown in FIG. 22 (the number of coding units = 0 or an actual silent code string). , Type flag = 2, and the number of skipped frames.
[0202]
The code string synthesizing unit 204 adds the code string supplied from the code string encrypting unit 83 to the end of the code string supplied from the type flag / skip frame number information adding unit 203. Generate the whole. The code string generated by the code string combining means 204 is output to the code string selecting means 205.
[0203]
The code string selecting means 205 includes a frame supplied from the encoding means 81, a frame supplied from the code string synthesizing means 86, a frame supplied from the code string synthesizing means 204 according to an instruction from the system controller 17 in FIG. And select one of them to output.
[0204]
FIG. 24 is a block diagram showing a configuration example of a decoder 53 that processes a code string as shown in FIG. The same components as those in FIG. 12 are denoted by the same reference numerals, and description thereof will be omitted as appropriate.
[0205]
The decoded frame selecting unit 211 selects a predetermined frame from the supplied code string based on the selection signal supplied from the type flag / skip frame number information inspecting unit 212, and sends the selected frame to the decoding unit 131. Output.
[0206]
The decoding unit 131 reproduces the code string supplied from the code frame selection unit 211 and outputs the obtained PCM signal to the signal selection unit 135. If the decryption unit 131 determines that the supplied frame is an encrypted frame as a result of decryption, the decryption unit 131 outputs the entire code string of the encrypted frame to the type flag / skip frame number information inspection unit 212.
[0207]
The type flag / skip frame number information checking means 212 takes the value of 1 at the time of the trial listening and 0 after the purchase of the encryption / decryption key, and has the same value as the trial mode flag based on the trial mode flag supplied from the system controller 17. Is output to the signal selection means 135.
[0208]
At the time of trial listening, and when the value of the type flag described in the frame to be processed is 2, the type flag / skip frame number information checking unit 212 determines that the number of frames to be decoded is equal to the number specified by the number of skip frames. A signal indicating skipping is output to decoded frame selecting means 211.
[0209]
When the type flag takes a value of 1 or 2, the type flag / skip frame number information inspection unit 212 outputs the encrypted code string after the type flag to the encryption / decryption unit 133.
[0210]
The encryption / decryption unit 133 decodes the code string supplied from the type flag / skip frame number information inspection unit 212 using the encryption / decryption key supplied from the system controller 17, and sends the obtained decryption result to the decryption unit 134. Output. The decoding means 134 decodes (reproduces) the code string supplied from the encryption / decryption means 133 and outputs the obtained PCM signal to the signal selection means 135.
[0211]
When the value of the selection signal supplied from the type flag / skip frame number information inspection unit 212 is 1 (during trial listening), the signal selection unit 135 converts the PCM signal supplied from the decoding unit 131 into an external D signal. / A converter 54 (FIG. 1). On the other hand, when the value of the selection signal is 0 (at the time of reproduction after purchase of the encryption / decryption key), the PCM signal supplied from the decryption means 134 is externally output. Output to
[0212]
Next, with reference to a flowchart of FIG. 25, a process of performing encoding by software to generate an audio code string as shown in FIG. 22 will be described.
[0213]
Here, the case where the audio code string is generated by software will be described. However, the same processing is naturally performed by hardware having each configuration as shown in FIG. 23, and the audio code string is generated. You.
[0214]
In step S101, 1 is set to a variable J indicating the number of the frame to be encoded, and the process proceeds to step S102. In step S102, whether or not the frame is an encrypted frame is determined based on the value of the variable J. That is, the information specifying the encrypted frame is determined and input by, for example, the administrator.
[0215]
If it is determined in step S102 that the current frame to be encoded is not to be an encrypted frame, the process proceeds to step S103, in which the input audio signal is encoded by the codec, and the process proceeds to step S104. In step S104, recording of the audio signal encoded in step S103 (description of quantization coefficient data, normalization coefficient data, spectrum coefficient data, and the like on the magneto-optical disk 11) is performed.
[0216]
In step S105, the value 0 is recorded in all the empty areas formed in the frame, and the process proceeds to step S106, where it is determined whether the processed frame is the last frame. As a result, a frame that can be previewed is generated and recorded.
[0219]
If it is determined in step S106 that the processed frame is not the last frame, the process proceeds to step S107, after the value of the variable J is increased by 1, returns to step S102, and the subsequent processes are repeated.
[0218]
On the other hand, if it is determined in step S102 that the frame to be encoded is an encrypted frame, the process proceeds to step S108, and a silence code sequence having a specific pattern instructing to output silence during the reproduction period is generated. Encoded.
[0219]
The generated silence code string is recorded in step S109, and proceeds to step S110. In step S110, it is determined whether or not the encrypted frame to be processed is the first encrypted frame in the frame sequence including the plurality of encrypted frames. If it is determined that the encrypted frame is the first frame, step S111 Then, the type flag is set to 2 and the number of skipped frames is recorded. After that, it advances to step S113.
[0220]
On the other hand, when it is determined in step S110 that the encrypted frame to be processed is not the first frame of the frame sequence including the plurality of encrypted frames, the process proceeds to step S112, where the type flag is set to 1 and the dummy flag is set. Is recorded. After that, it advances to step S113.
[0221]
In step S113, the input audio signal is encoded by the codec, and the process proceeds to step S114, where encryption is performed. Also, the encrypted input audio signal is recorded following the skip frame number (dummy skip frame number) added in step S111 or S112. Thereby, for example, a frame 1 or 2 as shown in FIG. 22 is generated and recorded on the magneto-optical disk 11.
[0222]
Thereafter, the process proceeds to step S106, and the subsequent processes are repeated. If it is determined in step S106 that the processed frame is the last frame, the process ends.
[0223]
Next, with reference to a flowchart of FIG. 26, a description will be given of a process of software for reproducing the audio code string generated by the process of FIG.
[0224]
In step S121, 1 is set to a variable J indicating the number of the frame to be decoded, and the process proceeds to step S122. In step S122, the frame to be decrypted is decrypted, and the flow advances to step S123 to determine whether the decrypted frame is an encrypted frame.
[0225]
If it is determined in step S123 that the decrypted frame is not an encrypted frame, the process proceeds to step S124, where the audio signal decrypted in step S122 is reproduced. Therefore, when the frame to be decoded is a frame that can be previewed, a preview sound that is the decoding result is output.
[0226]
In step S125, it is determined whether or not the processed frame is the last frame. If it is determined that the processed frame is not the last frame, the process proceeds to step S126. After the value of the variable J is increased by 1, the process returns to step S122. Subsequent processing is repeated.
[0227]
On the other hand, when it is determined in step S123 that the decrypted frame is an encrypted frame, the process proceeds to step S127, and whether the type flag is 2, that is, the target encrypted frame is It is determined whether or not this is the first frame of the frame sequence.
[0228]
If it is determined in step S127 that the value of the type flag is not 2 (for example, 0), the process proceeds to step S124, and the audio signal decoded in step S122 is reproduced. Note that the processing of an encrypted frame whose type flag value is 1 is basically skipped.
[0229]
On the other hand, if it is determined in step S127 that the value of the type flag is 2, the process proceeds to step S128, where the number of skip frames described after the type flag is read, and the value is set to K, and the process proceeds to step S129. , The value of the variable J is added by K, and the process returns to step S122. Therefore, the frame to be processed is skipped by K frames and is not processed.
[0230]
The above processing is repeatedly executed, and when it is determined in step S125 that the reproduced frame is the last frame, the processing ends. As a result, for example, only the trial listening portion is continuously reproduced.
[0231]
In the above description, the case where the number of skip frames is described only in the first frame sequence of the frame sequence of the encrypted frame has been described. However, not only the first encrypted frame of the frame sequence but also the subsequent encrypted frames are described. The number of skip frames can also be described in the frame. In this case, the processing frame is skipped based on the number of skipped frames described in the encrypted frames after the first encrypted frame.
[0232]
In the above description, silence is output (no sound is output) during the playback period of the encrypted frame. However, a predetermined sound other than noise output when the encrypted data is played back as it is is output. May be output. In this case, in the encrypted frame, data instructing to output such a predetermined sound is described separately from the encrypted data. Further, when the predetermined sound is a silent sound or the like, that part may be skipped (not output) and reproduced.
[0233]
As described above, these series of processes can be executed by hardware, but can also be executed by software. In this case, for example, the recording / reproducing apparatus 1 in FIG. 1 is configured by a personal computer 231 as shown in FIG.
[0234]
27, a CPU (Central Processing Unit) 241 has a program stored in a ROM (Read Only Memory) 242 or a program loaded from a HDD (Hard Disk Drive) 248 to a RAM (Random Access Memory) 243 according to a program. Execute various processes. The RAM 243 also appropriately stores data necessary for the CPU 241 to execute various processes.
[0235]
The CPU 241, the ROM 242, and the RAM 243 are mutually connected via a bus 244. The bus 244 is also connected to an input / output interface 245.
[0236]
The input / output interface 245 is connected to an input unit 246 including a keyboard and a mouse, an output unit 247 including a display, an HDD 248, and a communication unit 249. The communication unit 249 performs communication processing via a network.
[0237]
A drive 250 is connected to the input / output interface 245 as necessary, and a magnetic disk 251, an optical disk 252, a magneto-optical disk 253, a semiconductor memory 254, or the like is appropriately mounted. It is installed in the HDD 248 as needed.
[0238]
When a series of processing is executed by software, a program constituting the software executes various functions by installing a computer built in dedicated hardware or installing various programs. For example, it is installed from a network or a recording medium into a general-purpose personal computer or the like.
[0239]
As shown in FIG. 27, this recording medium is a magnetic disk 251 (including a floppy disk) storing the program, an optical disk 252, which is distributed to supply the program to the user separately from the apparatus main body. (Including a CD-ROM (Compact Disk-Read Only Memory), a DVD (Digital Versatile Disk)), a magneto-optical disk 253 (including an MD (Mini-Disk)), or a package medium including a semiconductor memory 254. Not only that, but also a ROM 242 and a HDD 248 that store the program and that are supplied to the user in a state of being incorporated in the apparatus main body in advance.
[0240]
In the present specification, the steps of describing a program stored in a recording medium include, in addition to the processing performed in chronological order in the order in which they are included, the processing is not necessarily performed in chronological order, but may be performed in parallel or individually. This includes the processing to be executed.
[0241]
【The invention's effect】
According to the first aspect of the present invention, a data string including encrypted data can be generated.
[0242]
Further, according to the first aspect of the present invention, it is possible to generate a data string capable of suppressing generation of noise even when encrypted data is included.
[0243]
According to the second aspect of the present invention, a data string including encrypted data can be reproduced.
[0244]
Further, according to the second aspect of the present invention, it is possible to suppress generation of noise even when the data includes encrypted data.
[Brief description of the drawings]
FIG. 1 is a block diagram illustrating a configuration example of a recording and reproducing apparatus to which the present invention has been applied.
FIG. 2 is a diagram illustrating an example of a code string described in a frame.
FIG. 3 is a diagram illustrating another example of a code string described in a frame.
FIG. 4 is a diagram showing still another example of a code string described in a frame.
FIG. 5 is a diagram illustrating an example of a code string described in a frame.
FIG. 6 is a block diagram illustrating a configuration example of the ATC encoder of FIG. 1;
FIG. 7 is a diagram illustrating an example of an audio code string.
FIG. 8 is a block diagram illustrating a configuration example of an encoding unit in FIG. 6;
9 is a block diagram illustrating a configuration example of a conversion unit in FIG. 8;
FIG. 10 is a diagram illustrating a spectrum signal and an encoding unit.
11 is a block diagram illustrating a configuration example of a signal component encoding unit in FIG. 8;
FIG. 12 is a block diagram illustrating a configuration example of an ATC decoder of FIG. 1;
13 is a block diagram illustrating a configuration example of a decoding unit in FIG.
FIG. 14 is a block diagram illustrating a configuration example of a signal component decoding unit in FIG. 13;
FIG. 15 is a block diagram illustrating a configuration example of an inverse conversion unit in FIG. 13;
FIG. 16 is a flowchart illustrating an audio code string generation process.
FIG. 17 is a flowchart illustrating a reproduction process of an audio code string.
FIG. 18 is a block diagram illustrating a configuration example of a recording apparatus.
FIG. 19 is a flowchart illustrating a recording process of an audio code string.
FIG. 20 is a diagram illustrating an example of a code string described in a frame.
FIG. 21 is a diagram illustrating another example of the audio code string.
FIG. 22 is a diagram illustrating another example of a code string described in a frame.
FIG. 23 is a block diagram illustrating another configuration example of the ATC encoder of FIG. 1;
FIG. 24 is a block diagram illustrating another configuration example of the ATC decoder of FIG. 1;
FIG. 25 is a flowchart illustrating an audio code string generation process.
FIG. 26 is a flowchart illustrating a reproduction process of an audio code string.
FIG. 27 is a block diagram illustrating a configuration example of a personal computer.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Recording / reproducing apparatus, 81, 82 encoding means, 83 code string encryption means, 84 silence code string generation means, 85 encryption flag addition means, 86 code string synthesis means, 87 code string selection means, 131, 134 decoding means , 132 encryption flag inspection means, 133 encryption / decryption means, 135 signal selection means, 181 code string selection means, 182 recording means

Claims (11)

In a data generation method for generating a data sequence from an input signal,
In the encrypted data frame including the encrypted data representing a part of the input signal, outputting a predetermined sound during the playback period of the encrypted data frame is transmitted to the data playback device that plays back the data sequence. An adding step of adding data to be instructed,
Generating a data sequence including the encrypted data frame and a data frame including data representing a part of the input signal. 2. The data generation method according to claim 1, wherein in the processing of the adding step, data instructing decryption from the first data frame after the encrypted data frame is further added. The data according to claim 2, wherein the data instructing decryption from the first data frame is added to a first encrypted data frame among a plurality of continuous encrypted data frames. Generation method. The data generation method according to claim 1, wherein the predetermined sound is silent. In a data generation device that generates a data sequence from an input signal,
In the encrypted data frame including the encrypted data representing a part of the input signal, outputting a predetermined sound during the playback period of the encrypted data frame is transmitted to the data playback device that plays back the data sequence. Adding means for adding data to be instructed,
A data generation apparatus comprising: a generation unit configured to generate the data sequence including the encrypted data frame and a data frame including data representing a part of the input signal. In a program for causing a computer to execute a process of generating a data sequence from an input signal,
In the encrypted data frame including the encrypted data representing a part of the input signal, outputting a predetermined sound during the playback period of the encrypted data frame is transmitted to the data playback device that plays back the data sequence. An adding step of adding data to be instructed,
A generating step of generating the data sequence including the encrypted data frame and a data frame including data representing a part of the input signal. An encrypted data frame including encrypted data representing a part of a predetermined signal, and a decoding step of decoding a data sequence including a data frame including data representing a part of the predetermined signal,
An output step of outputting a predetermined sound during a reproduction period of the encrypted data frame, when the frame to be decrypted by the processing of the decryption step is the encrypted data frame. In the processing by the decrypting step, when the encrypted data frame to be decrypted includes data instructing decryption from the first data frame after the encrypted data frame, the data to be decrypted is specified. The method according to claim 7, wherein decoding from a frame is performed. 8. The data reproducing method according to claim 7, wherein in the processing in the decoding step, when the decoded data is data representing silence, the reproduction based on the data representing the decoded silence is skipped. An encrypted data frame including encrypted data representing a part of the predetermined signal, and a decryption unit for decrypting a data sequence including a data frame including data representing a part of the predetermined signal;
When the frame to be decrypted by the decryption unit is the encrypted data frame, an output unit that outputs a predetermined sound during a playback period of the encrypted data frame is provided. An encrypted data frame including encrypted data representing a part of a predetermined signal, and a decoding step of decoding a data sequence including a data frame including data representing a part of the predetermined signal,
When the frame to be decrypted by the decrypting step is the encrypted data frame, the reproducing period of the encrypted data frame includes an output step of outputting a predetermined sound. Program.

Images