JP4691823B2 - Signal reproducing apparatus and method, signal recording apparatus and method, and signal processing method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a signal reproduction apparatus and method, a signal recording apparatus and method, and a signal processing method, and particularly, encodes a signal so that trial viewing is possible, and as a result, the trial viewer purchases the signal. If determined, a signal reproducing apparatus and method, and a signal recording apparatus, which enable high-quality reproduction and recording by adding data of a small amount of information, and further enable control of sound quality and image quality of trial viewing at any time And a signal processing method.
[0002]
[Prior art]
For example, a software distribution method is known in which a signal such as sound is encrypted and broadcast, or recorded on a recording medium, and only a person who has purchased a key is allowed to view it. As an encryption method, for example, an initial value of a random number sequence is given as a key signal to a bit sequence of a PCM acoustic signal, and an exclusive OR of the generated 0/1 random number sequence and the PCM bit sequence is taken. A method of transmitting a bit string or recording it on a recording medium is known. By using this method, only the person who obtained the key signal can reproduce the sound signal correctly, and the person who did not obtain the key signal can reproduce only the noise. Of course, a more complicated method can be used as the encryption method.
[0003]
On the other hand, methods of compressing and broadcasting an acoustic signal or recording on a recording medium have become widespread, and recording media such as magneto-optical disks capable of recording encoded audio or audio signals are widely used. ing.
[0004]
There are various techniques for high-efficiency encoding of signals such as audio or voice. For example, non-blocking frequency band that divides and encodes audio signals on the time axis into multiple frequency bands without blocking them Band-division coding (sub-band coding: SBC), which is a division method, or converting a time-axis signal into a signal on the frequency axis (spectrum conversion) and dividing it into a plurality of frequency bands. A block frequency band division method to be encoded, so-called transform encoding, and the like can be given. In addition, a high-efficiency coding method combining the above-described band division coding and transform coding is also considered. In this case, for example, after performing band division by the above band division coding, The signal for each band is spectrally converted into a signal on the frequency axis, and encoding is performed for each spectrum-converted band.
[0005]
As the filter described above, there is, for example, a QMF filter. The QMF filter is described in the document “1976, RECrochiere, Digital coding of speech in subbands, Bell Syst. Tech. J. Vol. 55, No. 8, 1976. " Also, the document “ICASSP 83, BOSTON, Polyphase Quadrature filters-A new subband coding technique, Joseph H. Rothweiler” describes an equal-bandwidth filter division technique.
[0006]
Here, as the above-described spectrum conversion, for example, an input audio signal is blocked in a predetermined unit time (frame), and discrete Fourier transform (DFT), cosine transform (DCT), modified DCT transform (MDCT), and the like for each block. There is a spectrum conversion in which the time axis is converted to the frequency axis by performing. MDCT is described in the document “ICASSP, 1987, Subband / Transform Coding Using Filter Bank Designs Based on Time Domain Aliasing Cancellation, J.P. Prince, A.B.Bradley, Univ. Of Surrey Royal Melbourne Inst. Of Tech.”.
[0007]
When the above-described DFT or DCT is used as a method for converting a waveform signal into a spectrum, M independent real data can be obtained by performing conversion in a time block consisting of M samples. In order to reduce the connection distortion between the time blocks, the adjacent blocks are usually overlapped by M1 samples, respectively. Therefore, on average, in DFT or DCT, there are M samples for (M-M1) samples. The real number data is quantized and encoded.
[0008]
On the other hand, when the above-described MDCT is used as a method of converting into a spectrum, M independent real number data is obtained from 2M samples overlapped by M times each adjacent time. In MDCT, M real data is quantized and encoded for M samples. In the decoding apparatus, the waveform signal can be reconstructed by adding the waveform elements obtained by performing the inverse transform in each block from the code obtained by using MDCT in this manner while interfering with each other. .
[0009]
In general, by increasing the time block for conversion, the frequency resolution of the spectrum is increased, and energy is concentrated on a specific spectral component. Therefore, by performing a conversion with a long block length by overlapping with both adjacent blocks by half, and using MDCT in which the number of obtained spectrum signals does not increase with respect to the number of original time samples, DFT or It is possible to perform encoding more efficiently than when DCT is used. Further, by providing a sufficiently long overlap between adjacent blocks, it is possible to reduce the inter-block distortion of the waveform signal.
[0010]
By quantizing the signal divided for each band by the filter and spectrum conversion in this way, the band where the quantization noise is generated can be controlled, and the characteristics such as the masking effect can be used to enhance the auditory efficiency. Encoding can be performed. If the normalization is performed for each band, for example, with the maximum absolute value of the signal component in that band before quantization, higher-efficiency encoding can be performed.
[0011]
As a frequency division width in the case of quantizing each frequency component obtained by frequency band division, for example, band division considering human auditory characteristics is performed. In other words, the audio signal may be divided into a plurality of bands (for example, 25 bands) in such a bandwidth that the bandwidth becomes wider as the high frequency band is generally called a critical band. In addition, when encoding data for each band at this time, encoding is performed by predetermined bit allocation for each band or adaptive bit allocation (bit allocation) for each band. For example, when the coefficient data obtained by the MDCT processing is encoded by the bit allocation, adaptive allocation bits are assigned to the MDCT coefficient data for each band obtained by the MDCT processing for each block. Encoding is performed with numbers.
[0012]
As such a bit allocation method, the following two methods are known. That is, first, in the document `` Adaptive Transform Coding of Speech Signals, R. Zelinski and P. Noll, IEEE Transactions of Accoustics, Speech, and Signal Processing, vol.ASSP-25, No.4, August 1977 '' Bit allocation is performed based on the signal size. In this method, the quantization noise spectrum is flattened and the noise energy is minimized. However, since the masking effect is not utilized in the sense of hearing, the actual noise feeling is not optimal. Also, in the document `` ICASSP 1980, The critical band coder-digital encoding of the perceptual requirements of the auditory system, MAKransner MIT '', the required signal-to-noise ratio is obtained for each band by using auditory masking. A method for performing fixed bit allocation is described. However, in this method, even when the characteristic is measured by sine wave input, the characteristic value is not so good because the bit allocation is fixed.
[0013]
In order to solve these problems, all the bits that can be used for bit allocation are divided into fixed bit allocation patterns determined in advance for each small block and bit allocation depending on the signal size of each block. There has been proposed a high-efficiency encoding device that is used in division, and that makes the division ratio depend on a signal related to an input signal, and increases the division ratio into the fixed bit allocation pattern as the spectrum of the signal is smoother.
[0014]
According to this method, when energy is concentrated on a specific spectrum, such as a sine wave input, the overall signal-to-noise characteristics can be significantly improved by assigning many bits to a block including that spectrum. it can. In general, human hearing is very sensitive to signals with steep spectral components, so using this method to improve signal-to-noise characteristics simply improves the numerical value of the measurement. Rather, it is effective in improving sound quality in terms of hearing.
[0015]
Many other bit allocation methods have been proposed, and the auditory model has been further refined, and if the coding device's ability is improved, more efficient coding can be achieved by hearing. . In these methods, it is common to obtain a real number bit allocation reference value that realizes the signal-to-noise characteristics obtained by calculation as faithfully as possible, and to use an integer value approximating it as the allocated bit number. .
[0016]
In addition, in the specification and drawings of Japanese Patent Application No. 5-152865 previously proposed by the present inventors, or in the specification and drawings of WO94 / 28633, a tone component that is particularly important for hearing from a spectrum signal, that is, around a specific frequency. A method has been proposed in which a signal component in which energy is concentrated is separated and encoded separately from other spectral components. This enables high compression of an audio signal and the like with little audible degradation. It is possible to efficiently encode at a rate.
[0017]
In constructing an actual code string, first, quantization accuracy information and normalized coefficient information are encoded with a predetermined number of bits for each band in which normalization and quantization are performed, and then normalized and quantized. The spectral signal may be encoded. Also,
ISO / IEC 11172-3: 1993 (E), 1993
Describes a high-efficiency coding scheme that is set so that the number of bits representing quantization accuracy information varies depending on the band, and the number of bits representing quantization accuracy information decreases as the frequency increases. It has been standardized.
[0018]
Instead of directly encoding quantization accuracy information, a method of determining quantization accuracy information from normalized coefficient information in a decoding device is also known, but in this method, normalization is performed when a standard is set. Since the relationship between the coefficient information and the quantization accuracy information is determined, it becomes impossible to introduce quantization accuracy control based on a more advanced auditory model in the future. If there is a range in the compression rate to be realized, it is necessary to define the relationship between the normalization coefficient information and the quantization accuracy information for each compression rate.
[0019]
Quantized spectral signals are encoded using, for example, variable length codes as described in the document `` DAHuffman: A Method for Construction of Minimum Redundancy Codes, Proc.IRE, 40, p.1098 (1952) ''. By doing so, a method of encoding more efficiently is also known.
[0020]
[Problems to be solved by the invention]
By the way, distribution of software in which a signal such as sound encoded by the method as described above is encrypted and broadcast, or recorded on a recording medium, and only the person who purchased the key is allowed to view the software. The method is known. As an encryption method, for example, an initial value of a random number sequence is given as a key signal to a bit string of a PCM (Pulse Code Moduration) acoustic signal or to a bit string of an encoded signal, and generated 0 There is known a method of transmitting a bit string obtained by exclusive ORing a random number sequence of / 1 and the bit string or recording the bit string on a recording medium. By using this method, only the person who obtained the key signal can reproduce the sound signal correctly, and the person who did not obtain the key signal can reproduce only the noise. Of course, a more complicated method can be used as the encryption method.
[0021]
However, in these scramble methods, if there is no key, or if it is played back by a normal playback means, it will become noise if it is played back, and the contents of the software cannot be grasped. For this reason, for example, a disc with music recorded at a relatively low sound quality is distributed so that those who have listened to it can purchase a key only for what they like and play it with high sound quality, or It was not possible to use it for the purpose of making it possible to purchase a new disc recorded with high sound quality after listening to the software.
[0022]
Conventionally, when a signal subjected to high-efficiency encoding is encrypted, it has been difficult to prevent the compression efficiency from being lowered while providing a code string that is meaningful for normal reproduction means. That is, as described above, when a code string formed by applying a high-efficiency code is scrambled, not only noise is generated even when the code string is reproduced, but the code string generated by the scramble is If the high-efficiency code standard is not met, the playback means may not operate at all. On the other hand, when high-efficiency encoding is performed after scrambling the PCM signal, for example, if the amount of information is reduced using the auditory property, at the time when the high-efficiency encoding is canceled, Since a PCM signal that has been scrambled cannot be reproduced, it is difficult to correctly cancel the scramble. For this reason, it is necessary to select a compression method that can correctly cancel the scramble even if efficiency is reduced.
[0023]
On the other hand, according to the technique described in Japanese Patent Laid-Open No. 10-135944 previously proposed by the present inventors, for example, a high frequency side of a music signal converted into a spectrum signal and encoded. An audio encoding method is disclosed that can be listened to without a key if only the signal is encrypted and a narrow-band signal is obtained. That is, in this method, for example, the high band side is encrypted and bit allocation information on the high band side is replaced with dummy data, and the true bit allocation information on the high band side is recorded at a position ignored by a normal decoder. is doing. If this method is adopted, for example, as a result of trial listening, it becomes possible to enjoy only favorite music with high sound quality.
[0024]
By the way, in the technique described in the above-mentioned Japanese Patent Application Laid-Open No. 10-135944, since its security depends only on encryption, in the unlikely event that the cipher is decrypted, the fee cannot be collected, There is a risk of listening to high-quality music.
[0025]
In addition, if the quality (sound quality or image quality) of trial viewing is determined by a predetermined encoding method, and it is desired to change the quality arbitrarily, it is necessary to change the encoding method.
[0026]
Furthermore, if the quality of the trial viewing (sound quality and image quality) is low, it is unclear how much signal quality you can enjoy after purchase, and it may be difficult to make a purchase decision. If high-quality trial viewing is possible, there may be many users who think that they can enjoy the game without purchasing it.
[0027]
The present invention has been proposed in view of the above-described circumstances, and can be trial-viewed, but can eliminate the risk of decryption without encrypting some signals. Further, the quality of the trial viewing (sound quality and image quality) can be arbitrarily changed, and further, a signal playback device that can confirm the quality of the signal that can be enjoyed after purchase, but the trial viewing signal is insufficient. It is an object to provide a method, a signal recording apparatus and method, and a signal processing method.
[0028]
[Means for Solving the Problems]
The present invention has been made in view of such circumstances, and in the present invention, a part of information to be recorded on a recording medium is recorded as dummy data so that it can be reproduced with completely silent or relatively low quality. In addition, for trial listening, partial additional information is sent to determine the sound quality of the trial listening, and when high quality playback is required, all or almost all dummy data is true data. By re-recording, the risk of decryption of the code is eliminated, and a medium recorded in any format that cannot be reproduced, low quality, or high quality can be viewed on a normal reproduction device.
[0029]
  That is, in order to solve the above-described problem, the signal reproduction apparatus and method according to the present invention reproduce at least one of the code sequences of the predetermined format when reproducing the code sequence of the predetermined format obtained by encoding the signal. Rewriting at least part of the dummy data using the partial code string of the second code string that complements the dummy data part for the first code string whose part is dummy data, Decodes the code string rewritten by the above partial code stringIn the encoding, the input signal is subjected to spectrum conversion, and band division is performed to generate a code string of a predetermined format including quantization accuracy information, normalization coefficient information, and spectrum coefficient information for each band, The dummy data is dummy data corresponding to information on at least the high frequency side of at least one of the quantization accuracy information, the normalized coefficient information, and the spectrum coefficient information, and the second code string The partial code string is information at least on the low frequency side of the information corresponding to the dummy data, and the bandwidth changes with time.
[0030]
  In the signal recording apparatus and method according to the present invention, when a code string having a predetermined format obtained by encoding a signal is recorded, at least a part of the code string having the predetermined format is dummy data. Rewriting at least a part of the dummy data using a partial code string of the second code string that complements the dummy data partIn the encoding, the input signal is subjected to spectrum conversion, band division, and a code string of a predetermined format including quantization accuracy information, normalization coefficient information, and spectrum coefficient information for each band is generated, and the dummy The data is dummy data corresponding to information on at least the high frequency side of at least one of the quantization accuracy information, the normalized coefficient information, and the spectral coefficient information, and is a part of the second code string The code string is information on at least the low frequency side of the information corresponding to the dummy data, and the bandwidth changes with time.This solves the above-mentioned problem.
[0031]
  Further, the signal processing method according to the present invention is a signal processing method for generating a code string of a predetermined format, wherein at least part of the first code string of the predetermined format is extracted as a second code string, and the extracted part Embedding dummy data in the first code string embedded with the dummy data, and using a partial code string of a second code string that complements the dummy data part for at least one of the dummy data Rewriting process to rewriteIn the encoding of the first code string, the input signal is subjected to spectrum conversion, band division, and a code in a predetermined format including quantization accuracy information, normalization coefficient information, and spectrum coefficient information for each band. A column is generated, and the dummy data is dummy data corresponding to information on at least a high frequency side of at least one of the quantization accuracy information, the normalized coefficient information, and the spectrum coefficient information. The partial code string of the second code string is information on at least the low frequency side of the information corresponding to the dummy data, and the bandwidth changes with time.This solves the above-mentioned problem.
[0032]
Here, in the encoding of the first code string, the input signal is subjected to spectrum conversion, band division, and a predetermined format including quantization accuracy information, normalization coefficient information, and spectrum coefficient information for each band. A code string is generated, and the dummy data is dummy data corresponding to a part of at least one of the quantization accuracy information, the normalized coefficient information, and the spectrum coefficient information. In this case, the dummy data is dummy data corresponding to a high frequency side of at least one of the quantization accuracy information, the normalized coefficient information, and the spectrum coefficient information, and the second code string The partial code string is information on the low frequency side of the information corresponding to the dummy data. Further, the partial code string of the second code string has a bandwidth that changes with time. Is to do.
[0033]
DETAILED DESCRIPTION OF THE INVENTION
First, prior to describing an embodiment according to the present invention, an optical disk recording / reproducing apparatus as a general compressed data recording / reproducing apparatus used for describing the embodiment of the present invention will be described with reference to the drawings.
[0034]
FIG. 1 is a block diagram showing an example of an optical disk recording / reproducing apparatus. In the apparatus shown in FIG. 1, a magneto-optical disk 1 rotated by a spindle motor 51 is used as a recording medium. When recording data on the magneto-optical disk 1, for example, a so-called magnetic field modulation recording is performed by applying a modulation magnetic field corresponding to the recording data with the magnetic head 54 in a state in which laser light is irradiated from the optical head 53. Data is recorded along the recording track. At the time of reproduction, the recording track of the magneto-optical disk 1 is traced with a laser beam by the optical head 53 and reproduced magneto-optically.
[0035]
The optical head 53 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 portion with a predetermined pattern. The optical head 53 is provided at a position facing the magnetic head 54 with the magneto-optical disk 1 interposed therebetween. When recording data on the magneto-optical disk 1, the magnetic head 54 is driven by a head driving circuit 66 of a recording system, which will be described later, and a modulation magnetic field according to the recording data is applied. By irradiating the track with laser light, thermomagnetic recording is performed by a magnetic field modulation method. The optical head 53 detects the reflected light of the laser light applied to the target track, detects a focus error by, for example, a so-called astigmatism method, and detects a tracking error by, for example, a so-called push-pull method. When reproducing data from the magneto-optical disk 1, the optical head 53 detects the focus error and the tracking error, and at the same time, detects and reproduces the difference in the polarization angle (Kerr rotation angle) of the reflected light from the target track of the laser beam. Generate a signal.
[0036]
The output of the optical head 53 is supplied to the RF circuit 55. The RF circuit 55 extracts the focus error signal and tracking error signal from the output of the optical head 53 and supplies the extracted focus error signal and tracking error signal to the servo control circuit 56, and also binarizes the reproduction signal and supplies it to a later-described reproduction system decoder 71. .
[0037]
The servo control circuit 56 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. The focus servo control circuit performs focus control of the optical system of the optical head 53 so that the focus error signal becomes zero. The tracking servo control circuit performs tracking control of the optical system of the optical head 53 so that the tracking error signal becomes zero. Further, the spindle motor servo control circuit controls the spindle motor 51 so as to rotationally drive the magneto-optical disk 1 at a predetermined rotational speed (for example, a constant linear speed). The sled servo control circuit moves the optical head 53 and the magnetic head 54 to the target track position of the magneto-optical disk 1 designated by the system controller 57. The servo control circuit 56 that performs such various control operations sends information indicating the operation state of each unit controlled by the servo control circuit 56 to the system controller 57.
[0038]
A key input operation unit 58 and a display unit 59 are connected to the system controller 57. The system controller 57 controls the recording system and the playback system based on the operation input information based on the operation input information from the key input operation unit 58. Further, the system controller 57 records the above-mentioned recording traced by the optical head 53 and the magnetic head 54 on the basis of the sector unit address information reproduced from the recording track of the magneto-optical disk 1 by the header time, subcode Q data, and the like. Manage recording and playback positions on tracks. Further, the system controller 57 controls the display unit 59 to display the playback time based on the data compression rate of the compressed data recording / playback apparatus and the playback position information on the recording track.
[0039]
This reproduction time display is a reciprocal of the data compression rate (for example, 1 / reverse number) for address information (absolute time information) in units of sectors reproduced from a recording track of the magneto-optical disk 1 by so-called header time or so-called subcode Q data. In the case of 4-compression, the actual time information is obtained by multiplying by 4), and this is displayed on the display unit 59. Even during recording, if absolute time information is recorded (preformatted) in advance on a recording track such as a magneto-optical disk, the preformatted absolute time information is read to obtain the data compression rate. It is also possible to display the current position with the actual recording time by multiplying the reciprocal.
[0040]
Next, in the recording system of the optical disk recording / reproducing apparatus shown in FIG. 1, an analog audio input signal A from the input terminal 60 is used._INIs supplied to the A / D converter 62 through the low-pass filter 61, and the A / D converter 62 receives the analog audio input signal A._INQuantize The digital audio signal obtained from the A / D converter 62 is supplied to an ATC (Adaptive Transform Coding) encoder 63. Also, a digital audio input signal D from the input terminal 67_INIs supplied to the ATC encoder 63 via the digital input interface circuit 68. The ATC encoder 63 receives the input signal A_INThe digital audio PCM data having a predetermined transfer rate quantized by the A / D converter 62 is subjected to bit compression (data compression) processing corresponding to a predetermined data compression rate, and is output from the ATC encoder 63. The compressed data (ATC data) is supplied to the memory (RAM) 64. For example, a case where the data compression rate is 1/8 will be described. The data transfer rate here is a so-called CD-DA format format data transfer rate (75 sectors / second) which is a standard digital audio CD format. It is reduced to 1/8 (9.375 sectors / second).
[0041]
Next, the memory (RAM) 64 is controlled by the system controller 57 to write and read data, temporarily stores ATC data supplied from the ATC encoder 63, and records it on a disk as necessary. Is used as a buffer memory. That is, for example, when the data compression rate is 1/8, the data transfer rate of the compressed audio data supplied from the ATC encoder 63 is the data transfer rate (75 sectors / second) of the standard CD-DA format. The compressed data is reduced to 1/8, that is, 9.375 sectors / second, and the compressed data is continuously written in the memory 64. The compressed data (ATC data) need only be recorded in one sector per eight sectors as described above. However, since recording in every eight sectors is practically impossible, the sector continuous data as described later is used. I try to record.
[0042]
This recording bursts at a data transfer rate (75 sectors / second) that is the same as the standard CD-DA format, with a cluster consisting of a predetermined number of sectors (for example, 32 sectors + several sectors) as a recording unit through a pause period. Done. That is, in the memory 64, ATC audio data having a data compression rate of 1/8, which is continuously written at a low transfer rate of 9.375 (= 75/8) sectors / second corresponding to the bit compression rate, is recorded data. Are read out in a burst manner at a transfer rate of 75 sectors / second. With respect to the data to be read and recorded, the overall data transfer rate including the recording pause period is a low rate of 9.375 sectors / second, but within the time of the recording operation performed in a burst manner. The instantaneous data transfer speed at the above is the standard 75 sectors / second. Therefore, when the disc rotation speed is the same as the standard CD-DA format (constant linear velocity), the same recording density and recording pattern as the CD-DA format are recorded.
[0043]
ATC audio data read out from the memory 64 in bursts at the (instantaneous) transfer rate of 75 sectors / second, that is, recording data is supplied to the encoder 65. Here, in the data string supplied from the memory 64 to the encoder 65, a unit that is continuously recorded in one recording is a cluster composed of a plurality of sectors (for example, 32 sectors) and a cluster connection arranged at positions before and after the cluster. For a few sectors. This sector for cluster connection is set longer than the interleave length in the encoder 65 so that the data in other clusters is not affected even if interleaved.
[0044]
The encoder 65 performs encoding processing (parity addition and interleaving processing) for error correction, EFM encoding processing, and the like on the recording data supplied in burst from the memory 64 as described above. The recording data subjected to the encoding process by the encoder 65 is supplied to the magnetic head driving circuit 66. The magnetic head driving circuit 66 is connected to the magnetic head 54 and drives the magnetic head 54 so as to apply a modulation magnetic field corresponding to the recording data to the magneto-optical disk 1.
[0045]
Further, the system controller 57 performs the memory control as described above for the memory 64 and continuously records the recording data read out from the memory 64 in bursts by the memory control on the recording tracks of the magneto-optical disk 1. Control the recording position. The control of the recording position is performed by managing the recording position of the recording data read out from the memory 64 in a burst manner by the system controller 57 and supplying a control signal for specifying the recording position on the recording track of the magneto-optical disk 1 to the servo control circuit. This is done by supplying to 56.
[0046]
Next, a playback system of the optical disk recording / playback apparatus shown in FIG. 1 will be described. This reproducing system is for reproducing the recording data continuously recorded on the recording track of the magneto-optical disk 1 by the above-described recording system. The optical head 53 causes the recording track of the magneto-optical disk 1 to be laser-beamed. The decoder 71 is provided with a reproduction output obtained by tracing with the RF circuit 55 after being binarized by the RF circuit 55. In this case, it is possible to read not only the magneto-optical disk but also the same read-only optical disk as a so-called CD (Compact Disc) or a so-called CD-R type optical disk.
[0047]
The decoder 71 corresponds to the encoder 65 in the recording system described above, and performs processing such as the above-described decoding processing for error correction and EFM decoding processing on the reproduction output binarized by the RF circuit 55. The ATC audio data with the data compression rate of 1/8 is reproduced at a transfer rate of 75 sectors / second, which is faster than the normal transfer rate. The reproduction data obtained by the decoder 71 is supplied to a memory (RAM) 72.
[0048]
In the memory (RAM) 72, data writing and reading are controlled by the system controller 57, and reproduction data supplied from the decoder 71 at a transfer rate of 75 sectors / second is written in bursts at the transfer rate of 75 sectors / second. It is. The reproduction data written in bursts at the transfer rate of 75 sectors / second is continuously read out from the memory 72 at a transfer rate of 9.375 sectors / second corresponding to the data compression rate 1/8. .
[0049]
The system controller 57 performs memory control such that the reproduction data is written in the memory 72 at a transfer rate of 75 sectors / second and the reproduction data is continuously read from the memory 72 at the transfer rate of 9.375 sectors / second. . The system controller 57 performs the memory control as described above for the memory 72 and continuously reproduces the reproduction data written in burst from the memory 72 from the recording track of the magneto-optical disk 1 by the memory control. Control the playback position. The reproduction position is controlled by managing the reproduction position of the reproduction data read out from the memory 72 in a burst manner by the system controller 57 and providing a control signal for designating the reproduction position on the recording track of the magneto-optical disk 1 or the optical disk 1. This is performed by supplying the servo control circuit 56.
[0050]
ATC audio data obtained as reproduction data continuously read from the memory 72 at a transfer rate of 9.375 sectors / second is supplied to the ATC decoder 73. The ATC decoder 73 corresponds to the ATC encoder 63 of the recording system, and reproduces 16-bit digital audio data, for example, by expanding the ATC data by 8 times (bit expansion). The digital audio data from the ATC decoder 73 is supplied to the D / A converter 74.
[0051]
The D / A converter 74 converts the digital audio data supplied from the ATC decoder 73 into an analog signal, and outputs an analog audio output signal A._OUT Form. Analog audio signal A obtained by the D / A converter 74_OUTIs output from the output terminal 76 via the low-pass filter 75.
[0052]
Next, high-efficiency compression coding of signals will be described in detail. That is, refer to FIG. 2 and subsequent drawings regarding techniques for performing high-efficiency coding on input digital signals such as audio PCM signals using band division coding (SBC), adaptive transform coding (ATC), and adaptive bit allocation techniques. While explaining.
[0053]
FIG. 2 is a block diagram showing a specific example of an apparatus for encoding an acoustic waveform signal for use in explaining the embodiment of the present invention. In this example, the input signal waveform 101 is converted into a signal 102 of a signal frequency component by the conversion unit 1101, and then each component is encoded by the signal component encoding unit 1102, and the code string generation unit 1103 encodes the code string 104. Is generated.
[0054]
FIG. 3 shows a specific example of the conversion means 1101 of FIG. 2, and signals divided into two bands by a band division filter are converted into spectral signal components 221 and 222 of forward spectrum conversion means such as MDCT in the respective bands. . The signal 201 in FIG. 3 corresponds to the signal 101 in FIG. 2, and the signals 221 and 222 in FIG. 3 correspond to the signal 102 in FIG. In the conversion means of FIG. 3, the bandwidths of the signals 211 and 212 are ½ of the bandwidth of the signal 201 and are decimated to ½ of the signal 201. Various conversion means other than this specific example are conceivable. For example, the input signal may be directly converted into a spectrum signal by MDCT, or not DCT (Discrete Fourier Transform) or DCT (Discrete Cosine Transform). You may convert by. Although it is possible to divide a signal into band components by a so-called band division filter, it is convenient to use a method of converting the frequency components into frequency components by the above-described spectrum conversion in which a large number of frequency components are obtained with a relatively small amount of calculation.
[0055]
FIG. 4 shows a specific example of the signal component encoding unit 1102 in FIG. 2, and the input signal 301 is normalized for each predetermined band by the normalizing unit 1301 (signal 302), and then the quantization accuracy is determined. Based on the quantization accuracy information 303 calculated by the means 1302, the signal is quantized by the quantization means 1303 and extracted as a signal 304. The signal 301 in FIG. 4 corresponds to the signal 102 in FIG. 2, and the signal 304 in FIG. 4 corresponds to the signal 103 in FIG. 2. Here, in addition to the quantized signal component, the signal 304 includes a normalization coefficient. Information and quantization accuracy information are also included.
[0056]
FIG. 5 is a block diagram showing a specific example of a decoding device that outputs an acoustic signal from the code string generated by the encoding device shown in FIG. In this specific example, the code 402 of each signal component is extracted from the code string 401 by the code string decomposing means 1401, the signal component 403 is restored from the code 402 by the signal component decoding means 1402, and then the inverse converting means 1403. As a result, an acoustic waveform signal 404 is output.
[0057]
FIG. 6 is a specific example of the inverse conversion unit 1403 in FIG. 5, which corresponds to the specific example of the conversion unit in FIG. 3, and each band signal 511 obtained by the reverse spectrum conversion units 1501 and 1502. 512 is synthesized by the band synthesis filter 1511. Each of the signals 501 and 502 in FIG. 6 corresponds to the signal 403 in FIG. 5, and the signal 521 in FIG. 6 corresponds to the signal 404 in FIG.
[0058]
FIG. 7 is a specific example of the signal component decoding unit 1402 in FIG. 5. The signal 551 in FIG. 7 corresponds to the signal 402 in FIG. 5, and the signal 553 in FIG. 7 corresponds to the signal 403 in FIG. The spectrum signal 551 is dequantized by the dequantization means 1551 (signal 552), denormalized by the denormalization means 1552, and extracted as a signal 553.
[0059]
FIG. 8 is a diagram for explaining a conventional encoding method in the encoding apparatus shown in FIG. In the example of this figure, the spectrum signal is obtained by the conversion means of FIG. 3, and FIG. 8 shows the absolute value of the MDCT spectrum converted to level dB. The input signal is converted into, for example, 64 spectrum signals for each predetermined time block, and is normalized and quantized into, for example, eight bands b1 to b8 (hereinafter referred to as encoding units). Is done. By changing the quantization accuracy for each encoding unit according to the distribution method of frequency components, it is possible to perform audioly efficient encoding that minimizes deterioration in sound quality.
[0060]
FIG. 9 shows a specific example when the signal encoded as described above is recorded on a recording medium. In this specific example, a fixed-length header including the synchronization signal SC is attached to the head of each frame, and the number of encoding units UN is also recorded here. Next to the header, quantization accuracy information QN is recorded for the number of encoding units, and then normalized accuracy information NP is recorded for the number of encoding units. The normalized and quantized spectral coefficient information SP is recorded thereafter, but if the frame length is fixed, an empty area may be formed after the spectral coefficient information SP. The example of this figure is obtained by encoding the spectrum signal of FIG. 8, and the quantization accuracy information QN is illustrated from 6 bits of the lowest band encoding unit to 2 bits of the highest band encoding unit, for example. The normalized coefficient information NP is assigned as shown in the figure from a value of 46 of the lowest band encoding unit to a value of 22 of the highest coding unit, for example. As the normalization coefficient information NP, for example, a value proportional to the dB value is used.
[0061]
Compared to the method described above, it is possible to further increase the encoding efficiency. For example, among the quantized spectrum signals, a relatively short code length is assigned to a high frequency signal, and a relatively long code length is assigned to a low frequency signal, thereby increasing coding efficiency. be able to. Also, for example, by increasing the transform block length, the amount of sub-information such as quantization accuracy information and normalization coefficient information can be relatively reduced, and the frequency resolution is increased, so that the quantization accuracy is more precise on the frequency axis. Therefore, encoding efficiency can be improved.
[0062]
Furthermore, in the specification and drawings of Japanese Patent Application No. 5-152865 previously proposed by the present inventors, or in the specification and drawings of WO94 / 28633, a tone component that is particularly important for hearing from a spectrum signal, that is, around a specific frequency. A method has been proposed in which a signal component in which energy is concentrated is separated and encoded separately from other spectral components, and this makes the audio signal etc. high without causing any audible degradation. It is possible to efficiently encode at the compression rate.
[0063]
FIG. 10 is a diagram for explaining a method when encoding is performed using such a method. A code having a particularly high level is separated from a spectrum signal as tone components, for example, tone components Tn1 to Tn3. It shows how it becomes. For each tone component Tn1 to Tn3, position information such as position data Pos1 to Pos3 is also required, but the spectrum signal after extracting the tone components Tn1 to Tn3 can be quantized with a small number of bits. Therefore, if such a method is applied to a signal whose energy is concentrated on a specific spectrum signal, particularly efficient encoding becomes possible.
[0064]
FIG. 11 shows the configuration of the signal component encoding unit 1102 of FIG. 2 when the tone component is separated and encoded as described above. 2 is separated into a tone component (signal 602) and a non-tone component (signal 603) by the tone component separation means 1601, respectively. Are encoded by the encoding unit 1602 and the non-tone component encoding unit 1603 and are extracted as signals 604 and 605, respectively. The tone component encoding unit 1602 and the non-tone component encoding unit 1603 have the same configuration as that shown in FIG. 4, but the tone component encoding unit 1602 also encodes position information of the tone component.
[0065]
Similarly, FIG. 12 shows the configuration of the signal component decoding unit 1402 of FIG. 5 when decoding the encoded tone component separated as described above. The signal 701 in FIG. 12 corresponds to the signal 604 in FIG. 11, and the signal 702 in FIG. 12 corresponds to the signal 605 in FIG. The signal 701 is decoded by the tone component decoding unit 1701 and sent to the spectrum signal synthesizing unit 1703 as the signal 703, and the signal 702 is decoded by the non-tone component decoding unit 1702 and sent to the spectrum signal synthesizing unit 1703. The spectrum signal synthesizing unit 1703 synthesizes the tone component (signal 703) and the non-tone component (signal 704), and outputs it as a signal 705.
[0066]
FIG. 13 shows a specific example when the signal encoded as described above is recorded on a recording medium. In this specific example, the tone component is separated and encoded, and the code string is recorded in a portion between the header portion and the quantization accuracy information QN. For the tone component row, first, tone component number information TN is recorded, and then data of each tone component is recorded. The tone component data includes position information P, quantization accuracy information QN, normalization coefficient information NP, and spectral coefficient information SP. Furthermore, in this specific example, the conversion block length to be converted into a spectrum signal is twice as high as that in the specific example of FIG. 9, so that the frequency resolution is also increased. In comparison, a code string of an acoustic signal corresponding to twice the length is recorded in a frame having the same number of bytes.
[0067]
The above description describes the technology prior to the description of the embodiment of the present invention. However, in the embodiment of the present invention, for example, when applied to audio, a relatively low-quality audio signal is a content. The high-quality audio signal can be heard by purchasing a relatively small amount of additional data or the like and obtaining it.
[0068]
That is, in the embodiment of the present invention, for example, as shown in FIG. 14, dummy quantization accuracy data in the quantization accuracy information QN is encoded as shown in FIG. Data indicating 0-bit allocation is encoded for the four high frequency side encoding units, and dummy normal coefficient data in the normalization coefficient information NP is included in the four high frequency side encoding units. The normalization coefficient information 0 having the minimum value is encoded (in this specific example, the normalization coefficient takes a value proportional to the dB value). Thus, by setting the quantization accuracy information on the high frequency side to 0, the spectral coefficient information in the area Neg in FIG. 14 is actually ignored, and when this is reproduced by a normal reproduction device, FIG. Narrow band data having the spectrum as shown is reproduced. In addition, by encoding dummy data for the normalization coefficient information, it becomes more difficult to guess the quantization accuracy information and perform unauthorized high-quality reproduction.
[0069]
In such a signal reproducing apparatus and method used in the embodiment of the present invention, when reproducing a code string of a predetermined format obtained by encoding a signal, a part of the code string of the predetermined format is dummy data. The dummy data is rewritten with respect to the first code string determined by using a second code string that complements the dummy data portion, and the first code string and the rewritten code string are set in a predetermined manner. The output is switched according to the conditions.
[0070]
Further, the signal recording apparatus and method used in the embodiment of the present invention, when recording a code string of a predetermined format obtained by encoding a signal, at least a part of the code string of the predetermined format is dummy data. The dummy data is rewritten by using a second code string that complements the dummy data portion with respect to the first code string.
[0071]
Here, the quantization accuracy information and normalization coefficient information of the entire band can be replaced with dummy data. In this case, no meaningful data can be reproduced even if the data is reproduced by a normal reproducing apparatus. In order to perform trial viewing, a part of the dummy data is rewritten and reproduced by using the partial code string of the second code string (for example, data on the low frequency side of the quantization accuracy information and the normalization coefficient information). When high-quality signal reproduction is desired, quantization accuracy information and normalization coefficient information corresponding to the remaining dummy data, that is, codes of portions other than the partial code sequence in the second code sequence By obtaining the column by purchasing it as additional data, all of the dummy data can be complemented, whereby high-quality (high sound quality, high image quality) signal reproduction can be performed. Also, the quality of the trial viewing signal can be arbitrarily changed by changing the amount of the partial code string of the second code string.
[0072]
In the above example, both the quantization accuracy information and the normalization coefficient information are replaced with dummy data, but only one of them may be replaced with dummy data. When only the quantization accuracy information is dummy data of 0-bit data, narrowband data having a spectrum as shown in FIG. 15 is reproduced. On the other hand, if only the normalization coefficient information is dummy data having a value of 0, it will have a spectrum as shown in FIG. 16, and the high frequency spectrum will not be exactly 0, From the viewpoint of audibility, it is substantially the same as 0. In the embodiment of the present invention, this case is also referred to as a narrowband signal.
[0073]
Of the quantization accuracy information and the normalization coefficient information, which data is used as dummy data is different in terms of the risk that these true values will be estimated and reproduced in high quality. When both the quantization accuracy information and the normalization coefficient information are dummy data, it is safest because there is no data for estimating these true values. When only the quantization accuracy information is set to dummy data, for example, when the original bit allocation algorithm is to obtain quantization accuracy information based on the normalization coefficient, the quantization accuracy information is obtained using the normalization coefficient information as a clue. The risk is relatively high. On the other hand, since it is relatively difficult to obtain normalized coefficient information from quantization accuracy information, the method using only normalized coefficient information as dummy data is compared with the method using only quantization accuracy information as dummy data. The risk is lower. Note that the quantization accuracy information or the normalization coefficient information may be selectively used as dummy data depending on the band.
[0074]
In addition, part of the spectrum coefficient information may be replaced with zero dummy data. In particular, since the mid-range spectrum has an important meaning in terms of sound quality, this portion may be replaced with 0 dummy data, and the mid-high range portion may be replaced with dummy quantization accuracy information or dummy normalization coefficient information. In this case, the band replaced with dummy quantization accuracy information or dummy normalization coefficient information covers a band in which a part of the spectrum coefficient information is replaced with dummy data so that narrow band reproduction is performed correctly. In particular, when a variable length code is used for encoding spectral coefficient information, a part of the information in the middle region is lost, so that data in the higher region cannot be decoded at all.
[0075]
In any case, it is more difficult to guess a relatively large amount of data that enters the signal content than to decrypt a relatively short key length used in normal encryption. For example, the copyright of the song It can be said that the risk of illegally violating a person's rights is reduced. Also, even if dummy data is guessed for a song, unlike the case where the encryption algorithm decryption method is known, there is no risk of damage spreading to other songs. It can be said that the security is higher than when encryption is applied.
[0076]
FIG. 17 is a block diagram showing an example of a reproducing apparatus used in the embodiment of the present invention, which is an improvement of the conventional decoding means of FIG.
[0077]
In FIG. 17, an input signal 801 is a code string (first code string) partially replaced with dummy data. Here, quantization accuracy information and normalization coefficient information on the entire band or the high band side are stored. It is assumed that it is dummy data. A signal 801 that is a highly efficient encoded signal in which the dummy data is embedded is received via a predetermined public line (ISDN: Integrated Services Digital Network, satellite line, analog line, etc.), for example, and is separated into encoded strings. Input to means 1801. First, the content of the code string is decomposed by the code string decomposing means 1801 and sent as a signal 802 to the code string rewriting means 1802 and the selected terminal b of the changeover switch 1808. The code string rewriting means 1802 receives the true quantization accuracy information and the normalization coefficient information 806 as the second code string that complements the dummy data portion as the signal 807 through the control means 1805, and thereby the signal 802 The dummy quantization accuracy information and the normalization coefficient information are rewritten, and the result is sent to the selected terminal a of the changeover switch 1808. The output from the changeover switch 1808 is sent to the signal component decoding means 1803. The signal component decoding unit 1803 decodes this data into spectrum data 804, and the inverse conversion unit 1804 converts this data into time-series data 805 to reproduce the audio signal.
[0078]
In the configuration of FIG. 17, in the trial viewing mode, the signal 802 from the code string decomposing means 1801 bypasses the code string rewriting means 1802 and is decoded through the selected terminal b of the changeover switch 1808. Input to means 1803. In the purchase mode, true quantization accuracy information and / or true normalization coefficient information 806 for rewriting the above-described dummy data is input to the control means 1805 via the same public line as the signal 801. The control unit 1805 converts the dummy data in the high-efficiency encoded signal 801 embedded with the dummy data input to the code string rewriting unit 1802 into the true quantization accuracy information and / or the true normalization coefficient information 806. The rewritten high-efficiency encoded signal 803 is input to the signal component decoding means 1803 via the selected terminal a of the changeover switch 808.
[0079]
As a result, the user can listen to low-quality viewing music with dummy data added in the trial viewing mode, and high-quality music when a predetermined purchase procedure (billing processing, authentication processing, etc.) is performed. Can be heard.
[0080]
In the specific example described above, the case where all the dummy data is rewritten (supplemented) using the second code string has been described. However, the present invention is not limited to this, and at least a part of the dummy data is converted to the second data. It is also possible to rewrite and reproduce using a partial code string of the code string. Thus, when reproducing by replacing at least a part of the dummy data using the partial code string of the second code string, by arbitrarily changing the ratio of the partial code string of the second code string, For example, the quality of trial viewing (sound quality, image quality, etc.) can be arbitrarily changed. In this case, even in the trial viewing mode, the partial code string of the second code string is input to the control means 1805 as the signal 806 and sent to the code string rewriting means 1802 as the signal 807. A part of the dummy data embedded in the first code string from the code string decomposing means 1801 is rewritten using the partial code string of the second code string, and the changeover switch 1808 is switched and connected to the selected terminal a side. The signal component decoding means 1803 may be sent.
[0081]
Here, as the above encoding method, the content signal is subjected to spectrum conversion, band division, and a code string of a predetermined format including quantization accuracy information, normalization coefficient information, and spectrum coefficient information for each band is generated. In such a system, the dummy data is dummy data corresponding to at least a part of at least one of the quantization accuracy information, the normalized coefficient information, and the spectrum coefficient information. In this case, the partial code string of the second code string may be information on the low frequency side of the dummy data. Specifically, for example, when the dummy data is dummy data of information on the high frequency side of the quantization accuracy information or information on the high frequency side of the normalized coefficient information, the partial code sequence of the second code sequence is Quantization accuracy information corresponding to the dummy data, or information on the low frequency side of the normalization coefficient information.
[0082]
If the data for rewriting the dummy data (partial code string of the second code string) is for the entire band of information corresponding to the dummy data or a band close to the entire band, An audio signal is played back. When the data for rewriting dummy data (partial code string of the second code string) is for a narrow band of a part of the information corresponding to the dummy data, a narrow band audio signal is reproduced. As a result, the sound quality of the trial listening can be controlled and a wideband audio signal can be reproduced depending on which bandwidth the dummy data rewriting data corresponds to.
[0083]
In the embodiment described above, the high-efficiency encoded signal 801 in which dummy data is embedded and true quantization accuracy information and / or true normalization coefficient information (second code string or (Partial code string) 806 is obtained from the server side through the same public line. For example, a high-efficiency encoded signal 801 in which dummy data having a large amount of data is embedded is obtained through a satellite line having a high transmission rate. However, true quantization accuracy information and / or true normalization coefficient information 806 with a small amount of data may be obtained separately using a line with a relatively low transmission rate such as a telephone line or ISDN. Further, the signal 801 may be supplied by a large-capacity recording medium such as a CD-ROM or a DVD (Digital Versatile Disc) -ROM. With the above configuration, security can be enhanced.
[0084]
In FIG. 13, the tone component and the non-tone component have been described. However, the high-efficiency encoded signal in which the dummy data is embedded corresponds to the quantization accuracy information and / or the normalization coefficient information constituting the tone component. May be performed on the quantization accuracy information and / or normalization coefficient information constituting the non-tone component, and / or the quantization accuracy information on both the tone component and the non-tone component, and / or It may be performed on the normalization coefficient information.
[0085]
Next, FIG. 18 shows a specific example of the format of the true information (second code string) of the signal 807 from the control means 1805 of FIG. 17, and the information of the Nth frame shown in FIG. It is for changing to the information shown in FIG. As a result, in the code string with the dummy data still included, the reproduced sound having the spectrum shown in FIG. 15 changes to the reproduced sound having the spectrum shown in FIG.
[0086]
FIG. 19 is a block diagram showing an example of recording means used in the embodiment of the present invention. In FIG. 19, an input signal 821 is a first code string that is partially replaced with dummy data. Here, the high-frequency quantization accuracy information and normalization coefficient information are dummy data. And First, the content of the code string is decomposed by the code string decomposing means 1821 and sent to the code string rewriting means 1822 as a signal 822. The code string rewriting means 1822 receives the true quantization accuracy information and the normalized coefficient information 825 as the second code string as the signal 826 through the control means 1824, and thereby the dummy quantization of the signal 822 is performed. The accuracy information and the normalization coefficient information are rewritten, and the resulting signal 823 is sent to the recording means 1823 and recorded on the recording medium. Here, the recording medium that records the code string of the signal 824 may be a recording medium that originally recorded the code string of the signal 821.
[0087]
In the embodiment of FIG. 19 as well, as in the example of FIG. 17 described above, instead of rewriting (complementing) all of the dummy data using the second code string, at least a part of the dummy data is replaced. The partial code string of the second code string may be rewritten and recorded. As described above, when recording by replacing at least a part of the dummy data using the partial code string of the second code string, by arbitrarily changing the ratio of the partial code string of the second code string, For example, the quality of trial viewing (sound quality, image quality, etc.) can be arbitrarily changed. In this case, even in the trial viewing mode, the partial code string of the second code string is input to the control means 1824 as the signal 825 and sent to the code string rewriting means 1822 as the signal 826. A part of the dummy data embedded in the first code string from the code string decomposing means 1821 may be rewritten using the partial code string of the second code string and sent to the recording means 1823.
[0088]
As described above, the reproducing apparatus and the recording apparatus used in the embodiment of the present invention have been described. Here, the spectral coefficient information on the high frequency side is encrypted to further increase the safety. Is also possible. In that case, the code string rewriting means 1802 and 1822 for replacing the dummy data in FIGS. 17 and 19 receive the true normalization coefficient information through the control means 1805 and 1824, replace the dummy data, and also the control means 1805, Using the decryption key obtained through 1824, the data on the high frequency side is decrypted to be reproduced or recorded.
[0089]
FIG. 20 shows a specific example of the format of information for replacing dummy data when tone components are separated as shown in FIG. 10 and encoded as shown in FIG. As a result, the reproduced sound having the spectrum shown in FIG. 15 is changed to the reproduced sound having the spectrum shown in FIG.
[0090]
FIG. 21 is an example of a flowchart showing a procedure in the case where reproduction is performed using software in the reproduction method used in the embodiment of the present invention. First, in step S11, a code string (first code string) including dummy data is decomposed, and then in step S12, it is determined whether or not high sound quality reproduction is to be performed. When performing high-quality sound reproduction, in step S13, the dummy data in the first code string is replaced with true data (second code string) for providing a wide band, and then the process proceeds to step S14. If not, the process proceeds directly to step S14. In step S14, the signal component is decoded, and in step S15, reverse conversion to a time-series signal is performed to reproduce the sound.
[0091]
FIG. 22 is an example of a flowchart showing a procedure when recording is performed using software in the recording method used in the embodiment of the present invention. First, in step S21, it is determined whether or not high sound quality recording is to be performed. When high sound quality recording is to be performed, first, in step S22, a code string (first code string) including dummy data is decomposed. Next, in step S23, the dummy data in the code string is replaced with true data (second code string) having a wide band, and then the process proceeds to step S24 to perform recording. Otherwise, step S21 is performed. Go directly to step S24.
[0092]
By the way, in the above-described embodiment, a part of the code string is not changed without changing the configuration of the code string of a predetermined format obtained by encoding the signal, that is, while complying with the standard of the existing code string format. Although the data is replaced with dummy data such as 0, it is also possible to remove this dummy data portion and close (shrink) the code string.
[0093]
23 shows the dummy quantization accuracy data (0) in the quantization accuracy information QN and the dummy normalization coefficient data (0) in the normalization coefficient information NP in the code string shown in FIG. A code string is shown that is deleted and packed with the remaining portion. In this case, it is necessary to write information such as the number of units of dummy data in the code string. For example, the number of dummy coding units may be written instead of the number of coding units UN, or undefined ( For example, the number of dummy encoding units is written in the (Reserved) area.
[0094]
When the dummy data is left as in the example shown in FIG. 14, the dummy data portion is overwritten with the second code string when the code string data is complemented later using the second code string. On the other hand, in the example shown in FIG. 23, a process of inserting the second code string into the portion from which the dummy data is deleted is necessary. However, in the example of FIG. 23, since the length of the code string is shortened by the dummy data of FIG. 14, there is an advantage that the amount of data to be transmitted or recorded can be reduced.
[0095]
As is apparent from the above description, in the encoding method used in the embodiment according to the present invention, a signal having a narrow reproduction band is reproduced by writing dummy data such as normalization coefficient data for each frame. However, it is also possible to change the reproduction band using dummy data such as the normalization coefficient data depending on each part of the music piece.
[0096]
That is, for example, encoding is performed without using dummy data such as normalization coefficient data so that a wide band can be reproduced in the frame of the beginning portion of the song and the so-called chorus portion of the song. In a partial frame, narrow band reproduction is performed using dummy data such as normalization coefficient data. Here, if the change in the reproduction band is performed smoothly over several frames, it is possible to reduce a sense of incongruity during trial listening (generally during trial viewing).
[0097]
FIG. 24 shows how the playback band changes during this audition according to this method. The playback band is widened at the beginning portion Ka of the song and the so-called chorus portion Kb. For example, the mid-high range cannot be reproduced by the dummy data.
[0098]
When this is generalized, the value of the control parameter for the quality (sound quality, image quality, etc.) of the reproduction signal of the first code stream for trial viewing is calculated in time when generating the first code string for the trial viewing code stream. It is intended to change. This reproduction quality control is performed by embedding dummy data in the code string, and the reproduction quality control parameter includes the bandwidth of the encoded signal. Further, when reproducing a code string of a predetermined format obtained by encoding a signal, the dummy data is compared with the first code string in which at least a part of the code string of the predetermined format is dummy data. When at least part of the dummy data is rewritten using the partial code string of the second code string that complements the part, and the code string rewritten by the partial code string of the second code string is decoded In the encoding, the input signal is subjected to spectrum conversion, band division, and a code string of a predetermined format including quantization accuracy information, normalization coefficient information, and spectrum coefficient information for each band is generated, and the dummy The data is a dummy corresponding to information on at least a high frequency side of at least one of the quantization accuracy information, the normalized coefficient information, and the spectrum coefficient information. A data, the partial code string of the second code string is at least lower frequency information of the information corresponding to the dummy data, and that the bandwidth is changed in time.
[0099]
Next, FIG. 25 is a block diagram showing a specific example of an encoding device for changing the quality of a reproduction signal according to each part of the music. In FIG. 25, the control means 1844 receives the information 845 that it is the head part of the music piece and the chorus part, so that the signal component encoding means 1842 uses dummy data such as normalization coefficient data, Control is performed so that the reproduction band changes.
[0100]
The other parts of FIG. 25 are the same as those of FIG. That is, the input signal waveform 841 is converted into a signal frequency component signal 842 by the conversion means 1841, and then each component is encoded by the signal component encoding means 1842, and the code string generation means 1843 generates the code string 844. Is done.
[0101]
FIG. 26 is a flowchart showing a flow of a specific example of processing in which the control means 1844 in FIG. 25 changes the reproduction band. First, the frame number N is set to 1 in step S31, and the process proceeds to step S32. In step S32, it is determined whether or not the current frame is a wide-band playback section such as the beginning portion or rust portion of the song. If so, dummy data such as normalization coefficient data is used so that wide-band playback is performed in step S33. Encoding is performed without using data, and the process proceeds to step S37. If not, the process proceeds to step S34. In step S34, it is determined whether or not the current frame is a band interpolation section before and after the wideband playback section. If so, dummy data such as normalization coefficient data is used so that the playback band gradually changes in step S35. Is used, and the process proceeds to step S37. If not, the process proceeds to step S36. In step S36, encoding is performed so that narrowband reproduction is performed using dummy data such as normalization coefficient data, and the process proceeds to step S37. In step S37, it is determined whether or not the current frame is the last frame. If so, the process ends. If not, the value of frame number N is incremented by 1 in step S38, and the next frame is reached. Proceed and return to the process of step S32.
[0102]
Here, the method of using dummy data such as normalization coefficient data is used to control the reproduction band in each frame, but the reproduction band is controlled by, for example, the present inventors. As described in the previously proposed technique of Japanese Patent Laid-Open No. 10-135944, a method of encrypting the high band side may be used.
FIG. 27 is a diagram showing a method of encrypting the high frequency side of each frame by the same method as described in Japanese Patent Laid-Open No. 10-135944. In the specific example of FIG. 27, the spectral coefficient information SP on the high frequency side._H , Normalization coefficient information NP on the high frequency side_H , High-frequency quantization accuracy information QN_H , And its encoding unit number UN is encrypted.
[0103]
In this way, by changing the bandwidth that can be auditioned by limiting the bandwidth in time, as shown in FIG. 24, another method of the embodiment of the present invention is possible, and the sound quality and contents of the song are also confirmed. Therefore, it is possible to enjoy music with high sound quality by decrypting the encryption.
[0104]
The example of the trial viewing and the method for improving the quality in the embodiment according to the present invention has been described above. The content supply system used in the embodiment of the present invention will be described below.
[0105]
FIG. 28 is a diagram for explaining the content supply system used in the embodiment of the present invention. Here, a center (content supply center) 1865 that stores and manages content and users used by each user are shown. Terminals 1861 to 1864 are connected to each other via a network (861 to 867), and each user terminal 1861 to 1864 is directly connected to a center 1865.
[0106]
FIG. 29 is a block diagram illustrating a specific example of each user terminal. This user terminal has communication means 1881 for communicating with a center or other user terminals by a signal 881 and control means 1882 for controlling them. Further, recording means 1884 and reproduction means 1885 are provided which can record trial listening data using dummy data sent from the center. As a result, each user can audition the trial listening data sent from the center as many times as possible. For example, the trial listening data sent from the center one after another in the middle of the night can be used as background music. In the daytime, it may be reproduced with a relatively low sound quality.
[0107]
On the other hand, this user terminal has a signal synthesizing means 1886 and a writing means 1887, and synthesizes audition data including dummy data and high-quality sound data including true normalization coefficient information that is not a dummy, A high-quality audio signal can be reproduced from the reproducing unit 1885 or recorded on the recording medium 1888 through the writing unit 1887. The high sound quality data is purchased through the control means 1882 when the user likes a specific music. The data is sent from the center after being encrypted and once recorded in the recording means 1884. And sent to the decryption means 1883.
[0108]
The descrambling means 1883 uses the decryption key 892 sent from the control means 1882 to decrypt the encrypted high quality sound data 886 and sends it to the signal synthesizing means 1886. Note that it is desirable from the viewpoint of data protection that the descrambling means 1883, the signal synthesizing means 1886, the writing means 1887, and the reproducing means 1885 are integrated in hardware.
[0109]
FIG. 30 is a block diagram showing a specific example of the control means of FIG. This control means has a right information storage means 1904 in addition to the CPU 1902, memory 1903 and input / output means 1901, and token information is stored in this right information storage means 1904. This token information is purchased in advance by the user, and the token information is reduced each time a song is purchased. Such right information storage means 1904 can be realized using, for example, an IC card. Note that the sound quality of each song, that is, the payment method for purchasing the song may be other than the prepaid method, for example, a credit card method.
[0110]
In the specific example of FIG. 28, the distribution of the trial listening data including the dummy data is performed using the same network as the high sound quality data. However, this is not always necessary, and a large amount of data is stored. Broadcasting that is easy to transmit or distribution by CD-ROM may be used.
[0111]
In addition, when distribution of trial listening data from the center to the user terminal is performed individually using a network or the like, a database is provided on the center side, and the trial listening data of the genre for which the user has purchased high quality sound data May be intensively transmitted to the user.
[0112]
As described above, in the content supply system according to the embodiment of the present invention, content data for trial viewing is transmitted from the center to the user terminal at no charge or at a low price, and the user terminal transmits the content for trial viewing. The user selects and purchases only the content he / she likes from the content so that it can be played back with high quality. Note that the trial listening content may be received by a free or low-cost membership system.
[0113]
Next, FIG. 31 is a diagram for explaining another example of the content supply system used in the embodiment of the present invention. In FIG. 31, a center (content supply center) 1865 and user terminals 1861 to 1864 are illustrated. Up to this point is the same as FIG. Here, first, the user terminal 1861 receives trial listening data 921 including dummy data and reproduced with relatively low sound quality from the center. Here, if the user likes this song, the user of the user terminal 1861 purchases the high-quality sound data 925 that replaces the dummy data with the true data. Further, the user thinks that this song may be liked by the user of the user terminal 1862, and sends a copy 922 of the data 921 to the user terminal 1862. At this time, the user of the user terminal 1862 can receive and play the trial listening data 922 free of charge or at a low price. Then, if the user of this user terminal 1862 likes this song, he / she purchases the sound quality enhancement data 926 having the same contents as the data 925 from the center 1865.
[0114]
Further, the user of the user terminal 1862 thinks that the user of the user terminal 1863 likes the song as well as the user of the user terminal 1861, and sends a copy 923 of the data 922 to the user terminal 1863. At this time, it is assumed that the user of the user terminal 1863 can obtain this copy for free or at a low price. If the user of the user terminal 1863 likes the song, the user can purchase the sound enhancement data 927 having the same content as the data 925 from the center 1865, and send a copy 924 of the data 923 to the user terminal 1864. Of course you can.
[0115]
In the same way, it is permitted to copy the trial data between users for free or at a low price, and only the user who likes the song after listening to it purchases the high quality sound data and plays the song with high sound quality. What can be heard is another example of the content supply system according to the embodiment of the present invention. Here, the trial listening data having dummy data is purchased as high-quality sound data, but of course, it is encrypted as in the technique described in the above-mentioned Japanese Patent Laid-Open No. 10-135944, for example. A key for solving the high frequency data may be purchased.
[0116]
Next, FIG. 32 is a diagram for explaining still another example of the content supply system in which the embodiment according to the present invention is used. In this system, first, an automatic installed in a convenience store, a so-called kiosk or the like. From the content supply terminal 1941 such as a vending machine, the trial listening data 941 narrowed using, for example, dummy data is written to the recording medium 1942 free of charge or at a low price, and this is attached to the playback terminal 1943 for playback. . Note that the trial listening content may be received by a free or low-cost membership system.
[0117]
FIG. 33 is a block diagram showing a specific example of the playback terminal of FIG. 32, and the recording medium 1968 is the same as the recording medium 1942 of FIG. The playback terminal also has a recording function as will be described later. The sample data recorded on the recording medium can be reproduced as much as desired by using the reading means 1966 and the reproducing means 1967. Here, if the user likes this song, the user purchases the high quality sound data 963 through the communication unit 1961 under the control unit 1962. The high-quality sound data 963 is encrypted in the same manner as in the example of FIG. 29, the descrambling is performed through the descrambling means 1963, and then the recording medium is once read out by the signal synthesizing means 1964 through the reading means 1966 The data 967, which is synthesized with the audition data including the dummy data read out from the data and improved in sound quality, is written into the recording medium 1968 through the writing means 1965.
[0118]
From the viewpoint of data protection, the descrambling means 1963, the signal synthesizing means 1964, and the writing means 1965 are preferably integrated in hardware.
[0119]
As a settlement method at the time of purchase, the same method as that shown in FIG. 29 can be applied. Further, here, the sound quality-enhancing data is purchased with respect to the trial listening data having dummy data. Of course, for example, as in the technique described in Japanese Patent Laid-Open No. 10-135944, the encryption It is also possible to purchase a key for solving the converted high frequency data. That is, in the content supply system described with FIG. 32 and FIG. 33, content data for trial viewing downloaded from a kiosk terminal or the like for free or at a low price is recorded on a recording medium, and the user side reproduces the content data. Then, the user selects only the content that he / she likes and purchases the high-quality sound data so that it can be reproduced with high quality.
[0120]
If the playback terminal in FIG. 32 only performs trial listening, the playback unit 1961, the descrambling unit 1963, the signal synthesizing unit 1964, the writing unit 1965, etc. may not be provided as in the playback terminal in FIG. Then, after sufficient trial listening is performed with the reproducing means of the normal recording medium 1942, the sound quality may be improved with a terminal as shown in FIG.
[0121]
In the above embodiment, the case where an audio signal is used has been described as an example. However, the present invention can also be applied to an image signal. That is, for example, when the image signal is converted for each block using a two-dimensional DCT and is quantized using various quantization tables, the high frequency component is dropped as a dummy quantization table. In the case of improving the image quality, it is possible to perform the same processing as in the case of the audio signal by replacing the high-frequency component with a true quantization table that does not drop the high-frequency component. .
[0122]
Of course, the present invention can be applied to a system in which the entire code string is encrypted and reproduced while being decrypted.
[0123]
In the above embodiment, the case where the encoded bit stream is recorded on the recording medium has been described. However, the method of the present invention can also be applied to the case where the bit stream is transmitted. For example, only the listener who has obtained the true normalization coefficient over the entire band can broadcast the audio signal being broadcast, and the content can be fully understood by other listeners. It is possible to reproduce with low sound quality.
[0124]
【The invention's effect】
The signal reproduction apparatus and method according to the present invention provides a first code in which at least a part of the code string of the predetermined format is dummy data when reproducing the code string of the predetermined format obtained by encoding the signal. Rewritten at least part of the dummy data by using the partial code string of the second code string that complements the dummy data part for the string, and rewritten by the partial code string of the second code string By decoding the code string, it is possible to determine whether the information necessary for high-quality playback should be obtained after confirming the content (software), and unlike the case of encryption, The risk of high-quality playback due to fraudulent acts such as cryptanalysis is reduced, enabling not only the smooth distribution of content, but also the second No. altering the partial code string of the column, for example, by varying the bandwidth, it is possible to arbitrarily change the quality (sound quality and image quality) of a signal for test viewing.
[0125]
Further, in the partial code string of the second code string, a value for controlling the quality of the reproduction signal changes with time. For example, a signal for trial viewing can be obtained by changing the bandwidth over time. The quality of a part of the song (for example, the beginning of the song or the rust portion) can be made high quality corresponding to the content after purchase, for example, making it easier to make a decision on purchase, and smoother content Distribution can be possible.
[0126]
In the signal recording apparatus and method according to the present invention, when a code string having a predetermined format obtained by encoding a signal is recorded, at least a part of the code string having the predetermined format is dummy data. Is necessary for high-quality reproduction by rewriting at least a part of the dummy data using a partial code string of the second code string that complements the dummy data part. It becomes possible to change to information.
[0127]
Furthermore, the signal processing method according to the present invention is a signal processing method for generating a code string of a predetermined format, wherein at least part of the first code string of the predetermined format is extracted as a second code string, and the extracted part Dummy data is embedded in the first code string in which the dummy data is embedded, and at least a part of the dummy data is obtained by using a partial code string of a second code string that complements the dummy data part. By rewriting, it is possible to determine whether information necessary for high-quality playback should be obtained after confirming the content (software), and to distribute software more smoothly It is possible to change the partial code sequence of the second code sequence, for example, by changing the bandwidth, It is possible to change the quality of the signal (sound quality and image quality) arbitrarily.
[0128]
Also in the case of this signal processing method, it is assumed that the value for controlling the quality of the reproduction signal of the partial code string of the second code string changes with time, for example, by changing the bandwidth over time. The quality of a part of the trial viewing signal (for example, the beginning of the song or the rust portion) can be made high quality corresponding to the content after the purchase, for example, and the purchase decision can be easily made. Therefore, it is possible to distribute contents more smoothly.
[0129]
Therefore, according to the present invention, it is possible to freely change the quality of a trial viewing signal for determining whether or not information necessary for high-quality reproduction should be obtained after confirming the content (software). In addition, unlike the case of encryption, the risk of high-quality playback due to illegal acts such as cryptanalysis is reduced, and after confirming both the content and quality, high-quality content Therefore, it is possible to distribute contents more smoothly and with high user satisfaction.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a schematic configuration of an optical disc recording / reproducing apparatus for explaining an embodiment of the present invention.
FIG. 2 is a block diagram showing a schematic configuration of an example of an encoding device for explaining an embodiment of the present invention;
FIG. 3 is a block diagram showing a specific example of conversion means of the encoding device of FIG. 2;
4 is a block diagram showing a specific example of signal component encoding means of the encoding apparatus of FIG. 2. FIG.
FIG. 5 is a block diagram showing a schematic configuration of an example of a decoding device for explaining an embodiment of the present invention;
6 is a block diagram showing a specific example of inverse conversion means of the decoding device of FIG. 5. FIG.
7 is a block diagram showing a specific example of signal component decoding means of the decoding apparatus of FIG. 5. FIG.
FIG. 8 is a diagram for explaining an encoding method for explaining an embodiment of the present invention;
[Fig. 9] Fig. 9 is a diagram for describing an example of a code string obtained by an encoding method used for describing an embodiment of the present invention.
[Fig. 10] Fig. 10 is a diagram for explaining another example of an encoding method for explaining an embodiment of the present invention.
FIG. 11 is a block diagram showing an example of signal component encoding means for realizing the encoding method described in conjunction with FIG.
12 is a block diagram illustrating an example of a signal component decoding unit used in a decoding device for decoding a code string obtained by the encoding method described with reference to FIG.
13 is a diagram illustrating an example of a code string obtained by the encoding method described with reference to FIG.
FIG. 14 is a diagram showing an example of a code string obtained by the encoding method used in the embodiment of the present invention.
FIG. 15 is a diagram illustrating an example of a spectrum of a reproduction signal when a code string obtained by the encoding method described with reference to FIG. 14 is reproduced.
16 is a diagram illustrating an example of a spectrum of a reproduction signal when a code string obtained by another example of the encoding method described with reference to FIG. 14 is reproduced.
FIG. 17 is a diagram illustrating a schematic configuration of a playback device for realizing the encoding method described with reference to FIG. 15;
FIG. 18 is a diagram illustrating an example of information for replacing dummy data in a code string obtained by the encoding method described with reference to FIG.
FIG. 19 is a block diagram showing a schematic configuration of a recording apparatus used in an embodiment of the present invention.
FIG. 20 is a diagram illustrating an example of information for replacing dummy data of a code string obtained by an encoding method used in another embodiment of the present invention.
FIG. 21 is a flowchart for explaining a reproduction method used in the embodiment of the present invention;
FIG. 22 is a flowchart for explaining a recording method used in the embodiment of the invention.
FIG. 23 is a diagram illustrating an example of a code string obtained by another encoding method used in the embodiment of the present invention.
FIG. 24 is a diagram for explaining a change with time of a code string used in the embodiment of the present invention.
FIG. 25 is a block diagram illustrating an example of an encoding device used in an embodiment of the present invention.
FIG. 26 is a flowchart for explaining an encoding method used in the embodiment of the present invention;
FIG. 27 is a diagram for explaining another encoding method used in the embodiment of the present invention.
FIG. 28 is a block diagram for explaining a content supply system according to an embodiment of the present invention.
FIG. 29 is a block diagram showing an example of a user terminal used in the content supply system of FIG.
30 is a block diagram showing an example of control means of the user terminal of FIG. 29. FIG.
FIG. 31 is a block diagram for explaining a content supply system according to another embodiment of the present invention.
FIG. 32 is a block diagram for explaining a content supply system according to still another embodiment of the present invention.
33 is a block diagram for explaining a playback terminal used in the content supply system of FIG. 32. FIG.
[Explanation of symbols]
1801, 1821 Code string decomposing means, 1802, 1822 Code string rewriting means, 1803 Signal component decoding means, 1804 Inverse conversion means, 1805, 1824, 1882, 1962 Control means, 1823, 1884 Recording means, 1861-1864 User terminal, 1865 Content supply center, 1881, 1961 communication means, 1883, 1963 descrambling means, 1885, 1967 playback means, 1886, 1964 signal synthesis means, 1887, 1965 writing means, 1888, 1942, 1968 recording medium, 1901 input / output means, 1902 CPU, 1903 memory, 1904 right information storage means, 1941 content supply terminal, 1943 playback terminal, 1966 reading means

Claims (5)

In a signal reproduction apparatus for reproducing a code string of a predetermined format obtained by encoding a signal,
For the first code string in which at least a part of the code string of the predetermined format is dummy data, at least the dummy data is obtained by using a partial code string of the second code string that complements the dummy data part. Rewriting means to rewrite part,
Have a decoding means for decoding a code string that has been rewritten by the partial code string of the second code string from said rewriting means,
In the above encoding, the input signal is spectrally converted and band-divided to generate a code string of a predetermined format including quantization accuracy information, normalization coefficient information, and spectrum coefficient information for each band,
The dummy data is dummy data corresponding to information on at least a high frequency side of at least one of the quantization accuracy information, the normalized coefficient information, and the spectrum coefficient information,
The partial code string of the second code string is information on at least a low frequency side of the information corresponding to the dummy data, and the signal reproducing apparatus whose bandwidth changes with time . In a signal reproduction method for reproducing a code string of a predetermined format obtained by encoding a signal,
For the first code string in which at least a part of the code string of the predetermined format is dummy data, at least the dummy data using the partial code string of the second code string that complements the dummy data part Rewriting process to rewrite a part,
Have a decoding step for decoding a code string that has been rewritten by the partial code string of the second code string from the redrawing process,
In the above encoding, the input signal is spectrally converted and band-divided to generate a code string of a predetermined format including quantization accuracy information, normalization coefficient information, and spectrum coefficient information for each band,
The dummy data is dummy data corresponding to information on at least a high frequency side of at least one of the quantization accuracy information, the normalized coefficient information, and the spectrum coefficient information,
The partial code string of the second code string is information on at least a low frequency side of information corresponding to the dummy data, and a signal reproduction method in which a bandwidth changes with time . In a signal recording apparatus for recording a code string of a predetermined format obtained by encoding a signal,
For the first code string in which at least a part of the code string of the predetermined format is dummy data, at least the dummy data is obtained by using a partial code string of the second code string that complements the dummy data part. It has a rewriting means for rewriting a part,
In the above encoding, the input signal is spectrally converted and band-divided to generate a code string of a predetermined format including quantization accuracy information, normalization coefficient information, and spectrum coefficient information for each band,
The dummy data is dummy data corresponding to information on at least a high frequency side of at least one of the quantization accuracy information, the normalized coefficient information, and the spectrum coefficient information,
The partial code string of the second code string is information on at least a low frequency side of information corresponding to the dummy data, and a signal recording device whose bandwidth varies with time . In a signal recording method for recording a code string of a predetermined format obtained by encoding a signal,
For the first code string in which at least a part of the code string of the predetermined format is dummy data, at least the dummy data using the partial code string of the second code string that complements the dummy data part It has a rewriting step of rewriting a part,
In the above encoding, the input signal is spectrally converted and band-divided to generate a code string of a predetermined format including quantization accuracy information, normalization coefficient information, and spectrum coefficient information for each band,
The dummy data is dummy data corresponding to information on at least a high frequency side of at least one of the quantization accuracy information, the normalized coefficient information, and the spectrum coefficient information,
The signal recording method in which the partial code string of the second code string is information on at least a low frequency side of the information corresponding to the dummy data, and the bandwidth changes with time . In a signal processing method for generating a code string of a predetermined format,
Extracting at least part of the first code string of the predetermined format as a second code string and embedding dummy data in the extracted part;
A rewriting step of rewriting at least a part of the dummy data using a partial code string of a second code string that complements the dummy data part for the first code string in which the dummy data is embedded. And
In the encoding of the first code string, the input signal is subjected to spectrum conversion, band division, and a code string in a predetermined format including quantization accuracy information, normalization coefficient information, and spectrum coefficient information for each band. Generate
The dummy data is dummy data corresponding to information on at least a high frequency side of at least one of the quantization accuracy information, the normalized coefficient information, and the spectrum coefficient information,
The partial code string of the second code string is information on at least a low frequency side of information corresponding to the dummy data, and a signal processing method in which a bandwidth changes with time .

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