JP4117502B2 - Digital signal transmission apparatus and digital signal transmission method - Google Patents

Description

The present invention relates to a transmission how the transmission apparatus and the digital signal of the digital signal, for example, a compact disk, can be applied to a recording and reproducing apparatus of a compact disc. The present invention digitally manipulates a digital signal so that the quality deteriorates to a perceptible level and can recover the quality deteriorated by a predetermined process, thereby enabling digital transmission to a conventional device. An audio signal can be transmitted and copyright can be effectively protected.

  Conventionally, in digital audio equipment such as a compact disc player, copyright is protected by SCMS (Serial Copy Management System).

  That is, the compact disc player binarizes the reproduction signal obtained by irradiating the compact disc with a laser beam to obtain reproduction data, which is subjected to EFM demodulation, error correction processing, deinterleaving processing, and digital audio signal. Reproduce. The compact disc player outputs the digital audio signal in a predetermined format to the digital audio device or the like while the digital audio signal is converted into a digital analog signal and output to the audio device having the analog signal input. To do. In this format, the compact disc player sets a code indicating copy prohibition, one-time copy permission, and unlimited copy permission, thereby protecting the copyright by reflecting the intention of the copyright holder. Yes.

  By the way, even when such a code is added and a digital audio signal is output, a device that operates ignoring this type of code may be copied indefinitely against the intention of the copyright holder.

  As one method for solving this problem, for example, a method of transmitting a digital audio signal after being scrambled can be considered. In the case of this method, for example, it is considered that various works can be protected according to the intention of the copyright holder by exchanging key data necessary for descrambling processing.

However, in this case, there is a problem that a digital audio signal cannot be transmitted to a conventional audio device.
Japanese Patent Laid-Open No. 10-135944 Japanese Patent Laid-Open No. 08-006879 Japanese Patent Laid-Open No. 10-069722

The present invention has been made in view of the above, can also transmit a digital signal to a conventional device, and transmits how the transmission apparatus and the digital signal of the digital signal can be effectively protect the copyright it is intended to propose.

In order to solve this problem, the invention of claim 1 is applied to a digital signal transmission device, and performs a predetermined arithmetic processing between digital signals of respective channels of an input digital signal made up of digital signals of a plurality of channels, thereby improving the quality. A quality deterioration means for generating a deteriorated digital signal and a transmission means for transmitting the quality deteriorated digital signal. The quality deterioration means performs addition processing and subtraction processing between the digital signals of the channels, and performs subtraction processing on the main signal and subtraction. When the subtracted signal can be expressed by only the lower bits, the arithmetic means for outputting the signal, and the lower bit of the main signal and the lower bits of the subtracted signal are assigned to the upper and lower bits respectively. When a signal is selected and output as a sub-signal, and the subtraction signal is difficult to express with only the lower bits, it is used for subtraction processing. And selection means for selecting and outputting digital signals of the channel as a sub-signal, the main signal and the sub signal and outputs the digital signal quality degradation.

According to a fourth aspect of the present invention, a predetermined arithmetic processing is performed between digital signals of respective channels of an input digital signal composed of a plurality of channels of digital signals to generate a quality-degraded digital signal, and the quality-degraded digital signal is transmitted. This is applicable to digital signal transmission methods that perform addition and subtraction processing between channel digital signals to output the main signal and subtraction signal, and the subtraction signal can be expressed only by the lower bits. In some cases, a composite signal in which the upper bits of the main signal and the lower bits of the subtraction signal are assigned to the upper and lower bits is selected and output as a sub-signal, and the subtraction signal is only the lower bits. When it is difficult to express, select the digital signal of the channel used for subtraction processing and output it as a sub signal And a step, and outputs the main signal and the sub signal as a digital signal quality degradation.

The invention according to claim 7 is applied to a digital signal transmission method, and the quality is deteriorated by performing predetermined arithmetic processing between the digital signals of the respective channels of the input digital signal composed of the digital signals of a plurality of channels. There is a quality recovery step in which a quality-degraded digital signal is input from a predetermined transmission line, and the quality of the quality-degraded digital signal is recovered by performing signal processing based on a predetermined calculation process. When the signal is a main signal and a sub signal, the main signal is generated by the addition process between the digital signals of the channels, and the subtraction signal by the subtraction process between the digital signals of the channels can be expressed by only the lower multiple bits, The upper bits of the main signal and the lower bits of the subtraction signal are assigned to the upper and lower bits, respectively. When the combined signal is selected and a sub-signal is generated, and the subtraction signal is difficult to express with only a plurality of lower bits, the digital signal of the channel subjected to the subtraction process is selected to generate the sub-signal, and quality recovery The step includes a comparison step for comparing the upper bits of the main signal with the upper bits of the sub signal, and the upper bits of the main signal and the sub signal based on the comparison result of the comparison step. When the higher-order multiple bits match, the comparison result of the first processing step for generating the digital signal of each channel of the input digital signal by the addition processing and subtraction processing of the main signal and the sub signal and the comparison result of the comparison step On the other hand, if the upper bits of the main signal do not match the upper bits of the sub signal, the sub signal is subtracted from the main signal and used to generate the main signal. To generate a digital signal of the channel, so that a second processing step of setting a sub-signal into a digital signal of the other channel.

According to a ninth aspect of the present invention , predetermined quality processing is performed by performing predetermined arithmetic processing between the digital signals of the respective channels of the input digital signal composed of a plurality of channels of digital signals, and transmitting a predetermined quality-degraded digital signal. This is applied to a digital signal transmission apparatus that recovers the quality of a digital signal that is input from a channel and deteriorates in quality by performing signal processing based on predetermined arithmetic processing. In the present invention, the quality-degraded digital signal is a main signal and a sub-signal, the main signal is generated by the addition processing between the digital signals of the channels, and the subtraction signal by the subtraction processing between the digital signals of the channels is a plurality of lower bits. When the combined signal is assigned to the upper and lower bits of the main signal and the lower bits of the subtraction signal, the sub signal is generated and the subtraction signal is lower. When it is difficult to express with only a plurality of bits, the digital signal of the channel subjected to the subtraction process is selected and a sub-signal is generated, and the transmission device transmits the upper bits of the main signal and the upper bits of the sub-signal. If the upper bits of the main signal match the upper bits of the sub signal based on the comparison result of the comparison unit and the comparison unit, A first arithmetic processing unit that generates a digital signal of each channel of the input digital signal by addition processing and subtraction processing of the signal and the sub-signal, and a plurality of upper bits of the main signal based on the comparison result of the comparison unit When the upper bits of the sub-signal do not match, the sub-signal is subtracted from the main signal to generate the digital signal of one channel used for generating the main signal, and the sub-signal is converted to the digital signal of the other channel. And a second arithmetic processing unit to be set.

If the quality-degraded digital signal is transmitted according to the configuration of the first, fourth , seventh , or ninth aspect , it can be used in a device that directly processes the transmitted digital signal. This makes it possible to transmit a digital signal to a conventional device. At this time, if copyright protection is suspected such that the digital signal is copied completely, the digital signal is copied with degraded quality, thereby protecting the copyright. On the other hand, in quality-degraded digital signals, the quality is reproducibly degraded, and in equipment that can reliably protect copyright, the quality is restored and the digital signal is processed, It is possible to provide a high-quality digital signal.

  According to the present invention, a digital signal is manipulated and transmitted so that the quality deteriorates to a perceptible level and the quality deteriorated by a predetermined process can be recovered. In addition, digital signals can be transmitted and copyright can be effectively protected.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings as appropriate.

(1) First Embodiment FIG. 1 is a block diagram showing an optical disk recording apparatus used for manufacturing a compact disk. In the first embodiment, a mother disk is produced by developing the disk master 2 exposed by the optical disk recording apparatus 1 and then electroforming it. Further, a compact disk is created using this mother disk. This example is an example as a reference example of the present invention.

  The master disc 2 to be exposed in this way is formed by applying a photosensitive agent to a flat glass substrate, for example. The spindle motor 3 rotationally drives the disk master 2 under the control of the spindle servo circuit 4. At this time, the spindle motor 3 outputs an FG signal FG whose signal level rises at every predetermined rotation angle by an FG signal generator provided at the bottom. The spindle servo circuit 4 drives the spindle motor 3 so that the FG signal FG has a predetermined frequency, thereby rotating the disk master 2 under the condition of a constant linear velocity.

  The recording laser 5 is composed of a gas laser or the like, and emits a laser beam having a predetermined light amount. The optical modulator 6 is composed of an electroacoustic optical element or the like, and performs on / off control of the laser beam L incident from the recording laser 5 according to the drive signal S3.

  The mirror 8 bends the optical path of the laser beam L and emits it toward the disc master 2. The objective lens 9 condenses the reflected light of the mirror 8 on the recording surface of the disc master 2. The mirror 8 and the objective lens 9 are sequentially moved in the radial direction of the disc master 2 in synchronization with the rotation of the disc master 2 by a thread mechanism (not shown). As a result, the optical disc recording apparatus 1 sequentially displaces the condensing position of the laser beam L in the outer circumferential direction of the disc master 2 to form a spiral track on the disc master 2. At this time, a pit row corresponding to the modulation signal S3 is formed on this track.

  The bit operation unit 10 receives 16-bit parallel audio data DA output from a predetermined server, and operates the lower 8 bits of the audio data DA. Here, the bit operation unit 10 divides the lower 8 bits in units of 2 bits, and operates these bits by converting a combination of 2 bits according to a predetermined rule. That is, as shown by the combination of 2 bits in FIG. 2, the combination of logic “00” is changed to the combination of logic “11”, and the combination of logic “01” is changed to the combination of logic “10”. . The combination of logic “10” and “11” is changed to a combination of logic “00” and “01”, respectively.

  As a result, the bit operation unit 10 deteriorates the sound quality, which is the quality of the digital audio signal, to such an extent that deterioration can be perceived. Furthermore, the sound quality is deteriorated so that the deteriorated sound quality can be recovered.

  The data processing circuit 11 inputs TOC data DI to be recorded in the lead-in area of the compact disc, and processes the TOC data DI according to a format defined for the compact disc. As a result, the data processing circuit 11 generates and outputs channel data corresponding to the pit string. Similarly, the data processing circuit 11 processes the digital signal D2 output from the bit operation unit 10 in accordance with a format defined for the compact disc, and generates and outputs channel data corresponding to the pit string.

  The TOC data to be recorded in this way is a disc identification data ID indicating that the digital audio signal DA is recorded by bit manipulation, and a copy identification indicating an original compact disc created from the mother disc. Data ICs are assigned. Thus, in this embodiment, at the time of reproduction, the bit-operated digital audio signal DA can be reproduced based on the detection result of the disc identification data ID. Further, based on the copy identification data IC, it is possible to determine whether the original compact disc or the copied compact disc.

  The drive circuit 12 receives the channel data D3 output from the data processing circuit 11 in this way, and generates a drive signal S3 whose signal level changes in accordance with the logic level of the channel data D3.

  As a result, in this embodiment, of the 16-bit data constituting the digital audio signal DA, 8 bits are recorded on the disc master 2 so as to be reproduced correctly by a normal compact disc player, and the remaining lower level is recorded. With respect to the 8 bits on the side, audio data reproduced on a normal compact disc can be correctly reproduced by performing bit operation according to the conversion rule described above with reference to FIG.

  Hereinafter, when the compact disc manufactured by the optical disc recording apparatus 1 of FIG. 1 is distinguished from the conventional compact disc, it is called an ECD disc.

  FIG. 3 is a block diagram showing a compact disc player, which reproduces a conventional compact disc and ECD disc. That is, in this compact disc player 20, the compact disc 21 is rotationally driven by the spindle motor 22 with a constant linear velocity on the basis of the reproduction signal RF obtained from the optical pickup 23.

  The RF circuit 24 amplifies and outputs the reproduction signal RF obtained from the optical pickup 23 with a predetermined gain, and the EFM (eight to fourteen) demodulation circuit 25 binary-identifies the reproduction signal output from the RF circuit 24. Generate playback data. Further, the EFM demodulating circuit 25 demodulates the reproduction data and outputs it.

  The CIRC decoder 26 descrambles the EFM demodulation circuit 25 and performs error correction processing using an error correction code added at the time of recording, thereby reproducing and outputting the digital audio signal D4. Accordingly, in the compact disc player 20, when the compact disc 21 is a conventional compact disc, the digital audio signal D4 is output with high sound quality of 16 bits, whereas when the compact disc 21 is an ECD disc, Of the 16 bits, the lower 8 bits are bit-operated, and the sound quality is degraded and output.

  The bit operation unit 28 performs bit operation on the lower 8 bits of the digital audio signal D4 so as to reversely follow the conversion rule described above with reference to FIG. As a result, when the compact disc 21 is an ECD disc, the bit operation unit 28 recovers and outputs the sound quality of the deteriorated digital audio signal D4.

  The disk discrimination unit 29 is configured by a system controller. Here, when the compact disk 21 is loaded, the system controller seeks the optical pickup 23, acquires information such as the number of songs and performance time recorded on the compact disk 21 from the lead-in area of the compact disk 21, It is displayed by the display means. At this time, the system controller also obtains the disc identification data ID of the compact disc 21, and determines whether the compact disc 21 is a conventional compact disc or an ECD disc according to the disc identification data ID. The disk discriminator 29 switches and controls the contacts of the selection circuit 30 based on the determination result.

  Further, the disc determination unit 29 determines whether or not the compact disc 21 is a compact disc by copying, based on the copy identification data IC obtained in the same manner. Here, such a compact disc by copying is created by dubbing the content recorded on the original compact disc by a computer onto a CD-ROM, for example. The disc discriminating unit 29 switches the operation of the switch circuit 34 based on the determination result, and thereby stops outputting the digital audio signal when the compact disc 21 is copied.

  When the compact disk 21 is a conventional compact disk, the selection circuit 30 selects and outputs the digital audio signal D4 output from the CIRC decoder 26 to the digital-analog conversion circuit (D / A) 31. Is an ECD disc, a digital audio signal from which the sound quality output from the bit operation unit 28 is restored is selectively output.

  The digital / analog conversion circuit 31 performs a digital / analog conversion process on the digital audio signal output from the selection circuit 30 and outputs an audio signal SA based on the analog signal. Thus, in the compact disc player 20, as shown in FIG. 4, the reproduction sound quality by analog signals is high sound quality equivalent to 16 bits (shown as CD sound quality) in both the conventional compact disc and the ECD disc. ) Can be played back. In FIG. 4, the compact disc 21 having the configuration shown in FIG. 3 is shown as an ECD player, and a conventional compact disc player is shown as a CD player. A conventional compact disc is shown as a CD disc, and the sound quality deteriorated by bit operation is shown as FM sound quality.

  In the conventional compact disc player, the digital audio signal D4 outputted from the CIRC decoder 26 is outputted without going through the bit operation unit 28, so that the CD sound quality is respectively obtained in the case of the conventional compact disc and ECD disc. And FM sound quality.

  The interface (I / F) 32 constitutes an input / output circuit for transmitting / receiving various data to / from an external device, etc., outputs a digital audio signal to a personal computer in the SCMS format, and relates to the digital audio signal. Send and receive various data.

  The external device discriminating unit 33 is configured by the system controller of the compact disc player 20 similarly to the disc discriminating unit 29, and executes a predetermined authentication process with the external device via the interface 32. In this authentication process, the external device determination unit 33 sends predetermined data to the external device, and the computer connected to the interface 32 protects the copyright by a response from the external device to this data. Determine whether it is a device.

  Here, the device for protecting the copyright in this way is a device having a function of prohibiting the creation of a copy (a so-called secondary copy) from a copy. For example, a compact disc player 20 like this compact disc player 20 is used. When the disk 21 is a copy, it means a device that can stop the output of the digital audio signal and prevent the recording of the digital audio signal by an external device. Therefore, for example, when the external device is a personal computer and a compact disc of a copy is created from the digital audio signal output from the compact disc player 20, the personal computer has a function of correctly setting the copy identification data IC. It corresponds to the device that protects copyright when it has it. (In FIG. 4, it is shown as a secondary copy prohibited PC by comparison with a conventional personal computer (conventional PC)).

  The selection circuit 35 selects and outputs the digital audio signal output from the selection circuit 30 based on the determination result of the external device determination unit 33 when the external device is a device that protects copyright. If the device is not a device for copyright protection, the digital audio signal S4 output from the CIRC decoder 26 is selectively output. As a result, the selection circuit 35 outputs a digital audio signal with high sound quality regardless of whether the external device is a device for protecting the copyright, whether the compact disc 21 is a conventional compact disc or an ECD disc. On the other hand, when the external device is not a device for protecting copyright, when the compact disc 21 is a conventional compact disc, it outputs a digital audio signal with high sound quality, whereas the compact disc 21 is an ECD disc. The digital audio signal is output with degraded sound quality.

  The switch circuit 34 outputs the digital audio signal output from the selection circuit 35 to an external device directly or via the interface 32. At this time, when the compact disc 21 is a copy disc, the switch circuit 34 stops outputting these digital audio signals based on the disc determination result by the disc determination unit 29.

  In the above configuration, in the compact disc manufacturing process (FIG. 1), the 16-bit digital audio signal DA is bit-operated in the lower 8 bits according to a certain rule in the bit operation unit 10 (FIG. 2). Sound quality is degraded as much as possible. The digital audio signal DA is then recorded on the master disc 2 in the same manner as when creating an ordinary compact disc, and then a mother disc and a stamper are sequentially produced from the master disc 2 and recorded on the compact disc from this stamper. Is done. On the other hand, in the conventional compact disc, the sound quality of the digital audio signal is recorded on the compact disc without any deterioration.

  In this way, when the master disc 2 is exposed, a lead-in area is formed by the TOC data output from a predetermined server, and recording is performed with the sound quality degraded by the disc identification data ID assigned to the TOC data. It is set so that it can be identified whether it is a compact disc or a conventional compact disc. Similarly, the copy identification data IC assigned to the TOC data is set so that it can be identified whether it is an original compact disc or a compact disc by copying.

  In the compact disc 21 thus produced, the reproduction signal detected by the optical pickup 23 in the compact disc player 20 (FIG. 3) is amplified by the RF circuit 24 and then demodulated by the EFM demodulation circuit 25. Reproduction data is generated, and the reproduction data is descrambled and error-corrected to output the original digital audio signal.

  In a conventional compact disc player, the digital audio signal D4 output from the CIRC decoder 26 after this error correction processing is output to an external device, and is converted into an analog signal and output. Thus, when a conventional compact disc player is loaded with a conventional compact disc player, a high-quality digital audio signal of 16 bits is directly or converted into an analog signal and output (FIG. 4). On the other hand, when an ECD disc is loaded on a conventional compact disc player, a digital audio signal is output by an amount corresponding to about 8 bits resulting in deterioration of sound quality.

  As a result, the compact disc can be reproduced by a conventional compact disc player.

  On the other hand, in the compact disc player 20 capable of reproducing the ECD disc, the digital audio signal output from the CIRC decoder 26 is input to the bit operation unit 28. Bit manipulated. As a result, when the compact disc 21 is an ECD disc, a digital audio signal obtained by restoring sound quality is output.

  In the compact disc player 20, the TOC data is reproduced in advance from the lead-in area of the compact disc, and based on the disc identification data ID assigned to the TOC data, whether the compact disc 21 is a conventional compact disc or an ECD disc. Determined. As a result, when the compact disc 21 is a conventional compact disc, the digital audio signal D4 output from the CIRC decoder 26 is transmitted to the external device in the SCMS format via the selection circuit 30, the selection circuit 35, the switch circuit 34, and the interface 32. Is output. Further, the digital audio signal D4 is input to the digital / analog conversion circuit 31 via the selection circuit 30, where it is converted into an analog signal and output.

  As a result, when playing back a conventional compact disc, it is possible to output the playback result with high sound quality to an external device and use it in various ways as in the case of playing back with a conventional compact disc player. Also, copyright protection can be achieved by SCMS. As a result, the compact disc player 20 can use a conventional compact disc without restricting the rights of existing users.

  On the other hand, when the compact disk 21 is an ECD disk, a digital audio signal whose sound quality is restored by the bit operation unit 28 is generated, and this digital audio signal is converted into an analog signal via the selection circuit 30 and the digital / analog conversion circuit 31. Is output by. As a result, ECD discs can be used to audition audio signals with high sound quality, as with conventional compact discs, and can be copied and enjoyed with high sound quality as before, only for analog signals. It becomes.

  On the other hand, when the compact disc 21 is an ECD disc and a digital audio signal is output to an external device, authentication processing is executed with the external device via the interface 32, and the external device is connected to a conventional personal computer. It is determined whether or not the device ignores the SCMS code, such as a computer. As a result, it is determined whether or not the external device is a device that protects the copyright, and in the case of the device that protects the copyright, the digital audio signal whose sound quality has been recovered by the bit operation unit 28 is the selection circuit 30, the selection circuit 35, and the switch. The data is output to an external device via the circuit 34 and the interface 32.

  As a result, a high-quality digital audio signal is output to an external device, and illegal copying such as creating a copy from a copy is prohibited because the external device is a device that protects copyright.

  On the other hand, if the external device is not a device that protects copyright, in this case, copying with an unlimited digital signal may be executed, so that the sound quality output from the CIRC decoder 26 in the compact disc player 20 is achieved. The digital audio signal D4 that has deteriorated is output to an external device via the selection circuit 35, the switch circuit 34, and the interface 32. As a result, when there is a possibility that copying with an unlimited digital signal is permitted, a digital audio signal with degraded sound quality is output as when copying is repeated with an analog signal. Thus, the advantage of copying with a digital signal that the image does not deteriorate cannot be utilized.

  On the other hand, in an external device for protecting copyright, a copy created by outputting a high-quality digital audio signal is recorded in the lead-in area when loaded on a compact disc player 20 of this type. In this compact disc player 20, the output of the digital audio signal is stopped by the switch circuit 34, so that the digital audio signal recorded on the ECD disc is converted into a high-quality digital audio signal. Even when output to an external device, unlimited copying is prevented.

  According to the above configuration, the sound quality of the digital audio signal is deteriorated so that the deterioration of the sound quality can be perceived and the recovered sound quality can be recovered, and the digital audio signal is recorded, so that the conventional compact disc player is recorded. Thus, a compact disc that can be reproduced and can effectively protect the copyright, and an optical disc recording apparatus that creates the compact disc can be obtained.

  Also, by judging the external device and outputting the digital audio signal recorded in this way directly or after restoring the sound quality, it is possible to reproduce a conventional compact disc and effectively protect the copyright. A compact disc player can be obtained.

(2) Second Embodiment In this embodiment, the optical disc recording apparatus exposes the master disc 2 with a digital audio signal having a deteriorated sound quality, like the optical disc recording apparatus 1 according to the first embodiment. At this time, the optical disk recording apparatus according to this embodiment is the same as that of the first embodiment at a constant period for a fixed period with reference to time information by a subcode added to the digital audio signal for recording. Performs bit manipulation processing. Thus, in this embodiment, the sound quality of the digital audio signal is deteriorated so that the deterioration can be perceived, and the deteriorated sound quality can be recovered. This example is an example as a reference example of the present invention.

  On the other hand, in the compact disc player, a digital audio signal is reproduced from the compact disc and output to an external device in the same manner as the compact disc player 20 according to the first embodiment. At this time, the compact disc player according to this embodiment obtains the subcode from the reproduction data obtained by reproducing the compact disc. Furthermore, time information is acquired from this subcode, and the sound quality of the digital audio signal reproduced based on this time information is recovered.

  According to the configuration of the second embodiment, the same bit operation as that of the first embodiment is repeated at a constant period on the basis of the time information assigned to the subcode, so that the same as the first embodiment. The effect of can be obtained. In particular, in the time information allocated to the subcode in this way, the subcode itself has a feature that it is difficult to copy it because it is not added to the digital audio signal and output. As a result, illegal copying can be prevented more effectively than in the first embodiment.

(3) Third Embodiment In this third embodiment, the optical disk recording apparatus deteriorates the sound quality of the digital audio signal in the same manner as the optical disk recording apparatus 1 according to the first or second embodiment, and the original disk is recorded. 2 is exposed. At this time, the optical disk recording apparatus according to this embodiment degrades the sound quality of the digital audio signal by encrypting the lower 8 bits of the digital audio signal by a technique such as public key cryptography and DES (Data Encryption Standard). To expose the disc master. Thus, in this embodiment, the sound quality of the digital audio signal is deteriorated so that the deterioration can be perceived, and the deteriorated sound quality can be recovered. This example is an example as a reference example of the present invention.

  On the other hand, in the compact disc player, a digital audio signal is reproduced from the compact disc and output to an external device in the same manner as the compact disc player 20 according to the first or second embodiment. At this time, in the compact disc player according to this embodiment, the sound quality of the digital audio signal is recovered by the processing corresponding to the encryption processing in the optical disc recording apparatus.

  According to the third embodiment, the same effect as in the first embodiment can be obtained even if the lower-order bits of the digital audio signal are encrypted to deteriorate the sound quality. Furthermore, by encrypting, it is possible to protect the copyright more powerfully.

(4) Fourth Embodiment In this embodiment, the optical disk recording apparatus exposes the master disk 2 with a digital audio signal having a deteriorated sound quality as in the optical disk recording apparatus 1 according to the first embodiment. This example is an example as a reference example of the present invention.

  That is, the optical disc recording apparatus inputs an 18-bit digital audio signal from the server, and generates a 16-bit digital audio signal with a sound quality deteriorated from the 18-bit digital audio signal in the bit operation unit.

  That is, as shown in FIG. 5, the bit operation unit 50 decomposes the 18-bit digital audio signal into the upper 8 bits and the lower 10 bits. Further, the bit operation unit 50 performs data compression processing or nonlinear quantization processing on the lower 10 bits by the data processing circuit 51 to generate an 8-bit digital audio signal.

  The bit operation unit 50 assigns the lower-order 8-bit digital audio signal and the higher-order 8-bit digital audio signal generated in this way to the higher-order 8 bits and the lower-order 8 bits, respectively, and combines the 16-bit synthesized digital signal. Generate an audio signal. As a result, in this embodiment, the sound quality of the digital audio signal is deteriorated by converting the 18-bit digital audio signal into the 16-bit synthesized digital audio signal so that the deterioration can be perceived, and the deteriorated sound quality can be recovered. To do. The optical disc recording apparatus exposes the disc master 2 with this synthesized digital audio signal to create a compact disc.

  On the other hand, in the compact disc player, a digital audio signal is reproduced from the compact disc and output to an external device in the same manner as the compact disc player 20 according to the first or second embodiment.

  At this time, in the compact disc player, the synthesized digital audio signal is reproduced from the reproduction data obtained from the compact disc, and the sound quality of the synthesized digital audio signal is recovered in the bit operation unit. That is, as shown in FIG. 6, the bit operation unit 52 restores the sound quality of the digital audio signal in the data processing circuit 53 by data expansion processing or non-linear inverse quantization processing corresponding to the processing in the optical disk recording apparatus, Selectively output.

  According to the fourth embodiment, even if the sound quality of the digital audio signal is deteriorated by the data compression process or the non-linear quantization process, the same effect as the above-described embodiment can be obtained. In addition, the audio quality of digital audio signals is degraded by data compression processing or non-linear quantization processing, and by further restoring the degraded audio quality, digital audio is further improved with respect to external equipment that protects copyrights. A signal can be output.

(5) Fifth Embodiment In this fifth embodiment, the optical disk recording apparatus exposes the master disk 2 by degrading the sound quality of the digital audio signal in the same manner as the optical disk recording apparatus 1 according to the above-described embodiment. . At this time, in the optical disk recording apparatus according to this embodiment, as shown in FIG. 7, the bit operation unit 55 uses a digital circuit for sound quality degradation by 8 bits to repeat in units of a predetermined number of frames by subcode in the arithmetic circuit 56. A signal PN is generated, and the lower 8 bits of the digital audio signal of the digital signal are calculated. Here, the calculation is executed by addition processing, subtraction processing, or exclusive OR calculation between corresponding bits. Thus, in this embodiment, the sound quality of the digital audio signal is deteriorated so that the deterioration can be perceived, and the deteriorated sound quality can be recovered. Note that the digital signal PN for sound quality deterioration is constituted by, for example, pseudo noise by a PN code. This example is an example as a reference example of the present invention.

  Correspondingly, the compact disc player obtains reproduction data from the compact disc in the same manner as the compact disc player according to the above-described embodiment, reproduces a digital audio signal from the reproduction data, and outputs it to an external device. At this time, in the compact disc player according to this embodiment, the bit operation unit 57 generates the digital signal PN for sound quality deterioration corresponding to the processing in the optical disc recording apparatus. Further, as shown in FIG. 8, the arithmetic circuit 58 performs arithmetic processing on the lower 8 bits of the reproduced digital audio signal and restores the sound quality of the digital audio signal.

  According to the fifth embodiment, even if arithmetic processing is performed on the digital signal for sound quality deterioration and the digital audio signal to deteriorate the sound quality of the digital audio signal, the same effect as the above-described embodiment can be obtained. it can.

(6) Sixth Embodiment In this sixth embodiment, the optical disc recording apparatus exposes the master disc 2 by deteriorating the sound quality of the digital audio signal in the same manner as the optical disc recording apparatus 1 according to the above-described embodiment. . At this time, in the optical disk recording apparatus according to this embodiment, as shown in FIG. 9, the master disk 2 is exposed so as to form the additional data recording area AR3 between the lead-out area AR4 and the user area AR2. To create a compact disc. This example is an example as a reference example of the present invention.

  Further, in the optical disc recording apparatus, setting is made so that the additional data recording area AR3 is not accessed in the conventional compact disc player by setting the TOC to be recorded in the lead-in area AR1. Further, a digital signal for sound quality deterioration (which is an 8-bit digital signal) which is periodically repeated in units of a predetermined frame (for example, 98 frames) of the digital audio signal is recorded in the additional data recording area AR3.

  Further, the additional data and the lower 8 bits of the digital audio signal are arithmetically processed on the basis of the time code, so that the sound quality of the digital audio signal can be deteriorated and the deteriorated sound quality can be recovered so that the deterioration can be perceived. To do. The optical disk recording apparatus records the digital audio signal with degraded sound quality in the user area AR2. The digital signal for deterioration of sound quality is composed of, for example, pseudo noise using a PN code.

  Correspondingly, the compact disc player obtains reproduction data from the compact disc in the same manner as the compact disc player according to the above-described embodiment, reproduces a digital audio signal from the reproduction data, and outputs it to an external device. At this time, if the compact disc player determines that the compact disc is an ECD disc from the TOC data, it accesses the additional data recording area AR3 to obtain a digital signal for sound quality degradation. Further, the digital audio signal reproduced on the basis of the time code and the digital signal for sound quality degradation are processed, thereby recovering the sound quality of the digital audio signal.

  According to the sixth embodiment, even if a digital signal necessary for restoring sound quality is separately recorded on a compact disc and transmitted, the same effect as the above-described embodiment can be obtained.

(7) Seventh Embodiment In this embodiment, the optical disc recording apparatus exposes the master disc 2 by degrading the sound quality of the digital audio signal in the same manner as the optical disc recording apparatus 1 according to the above-described embodiment. At this time, the optical disk recording apparatus manipulates the lower 8 bits of the digital audio signal by various methods such as encryption, and thereby records the sound quality of the digital audio signal deteriorated. Further, key data and the like necessary for restoring the sound quality of the deteriorated digital audio signal are recorded between the lead-out area and the user data. Thus, in this embodiment, the sound quality of the digital audio signal is deteriorated so that the deterioration can be perceived, and the deteriorated sound quality can be recovered. This example is an example as a reference example of the present invention.

  Correspondingly, the compact disc player obtains reproduction data from the compact disc in the same manner as the compact disc player according to the above-described embodiment, reproduces a digital audio signal from the reproduction data, and outputs it to an external device. At this time, the compact disc player reproduces the key data necessary for restoring the sound quality of the digital audio signal from the compact disc in advance, and restores the sound quality of the digital audio signal using this key data.

  According to the seventh embodiment, the sound quality is deteriorated by encryption or the like, and various data necessary for recovering the sound quality are separately recorded. An effect can be obtained.

(8) Eighth Embodiment In this embodiment, the optical disk recording apparatus decomposes a digital audio signal into upper 8 bits and lower 8 bits, and then, for example, the lower audio 8 in units of frames of the digital audio signal. Bits are replaced according to a predetermined rule to deteriorate the sound quality of the digital audio signal. As a result, the optical disk recording apparatus degrades the sound quality of the digital audio signal in a perceptible and recoverable manner by an operation in the time axis direction instead of the operation in the amplitude direction according to the above-described embodiment. The optical disc recording apparatus exposes the disc master with this digital audio signal. This example is an example as a reference example of the present invention.

Correspondingly, in the compact disc player according to this embodiment, the digital audio signal obtained by reproducing the compact disc is decomposed into the upper 8 bits and the lower 8 bits, and the operation in the time axis direction in the optical disc recording apparatus is performed. The lower 8 bits are exchanged corresponding to the above to restore the sound quality of the digital audio signal.

  Even if the digital audio signal is manipulated in the time axis direction to deteriorate the sound quality as in the eighth embodiment, the same effect as the above-described embodiment can be obtained.

(9) Ninth Embodiment In this embodiment, the optical disc recording apparatus exposes the disc master 2 with a digital audio signal with deteriorated sound quality in the same manner as the optical disc recording apparatus 1 according to the above-described embodiment.

  At this time, the optical disk recording apparatus processes the digital audio signal by the bit operation unit 61 shown in FIG. 10, and thereby operates the digital audio signal so that it is reproduced almost monaurally by a conventional compact disk player. As a result, the optical disk recording apparatus deteriorates the sound quality of the digital audio signal so that it can be perceived, and recovers the deterioration of the sound quality.

  In other words, the bit operation unit 61 inputs the digital audio signals R and L of the 16-bit right channel and left channel to the arithmetic circuit 62, and executes predetermined arithmetic processing between the corresponding data here ( A 16-bit, 2-channel digital audio signal represented by (R + L) / 2 and (RL) / 2 is generated.

  The bit operation unit 61 assigns the (R + L) / 2 digital audio signal LM, which is an addition signal, to the left channel in the conventional compact disc, and outputs it as a main digital audio signal.

  The comparison circuit 63 compares the higher 8 bits of the remaining digital audio signal represented by (RL) / 2 with the predetermined reference data REF, and generates (RL) in this way. ) / 2, it is determined whether or not the digital audio signal represented by (R−L) / 2 can be expressed by the lower 8 bits because the amount of data is small.

  The selection circuit 64 selectively outputs the composite digital audio signal DM and the right channel digital audio signal R based on the comparison result SEL of the comparison circuit 63. Here, the synthesized digital audio signal DM is composed of the lower 8 bits of the digital audio signal represented by (R−L) / 2 and the upper 8 bits of the digital audio signal LM of (R + L) / 2. It is generated by allocating to 8 bits and upper 8 bits.

  In other words, the selection circuit 64 is capable of expressing the digital audio signal represented by (RL) / 2 by the lower 8 bits, that is, the digital audio signal represented by (RL) / 2 is 8 bits. If there is no more overflow, the synthesized digital audio signal DM is selectively output.

  On the other hand, when the digital audio signal represented by (RL) / 2 is difficult to express by the lower 8 bits, that is, the digital audio signal represented by (RL) / 2 overflows from 8 bits. In this case, the digital audio signal R of the right channel is selected and output.

  The bit operation unit 61 assigns the digital audio signal LS output from the selection circuit 64 to the right channel in the conventional compact disc as a secondary digital audio signal and outputs the same.

  In this optical disc recording apparatus, the master disc is exposed with the two-channel digital audio signals LM and LS output from the bit operation unit 61. Accordingly, in this embodiment, the digital audio signal is manipulated between channels, and the sound quality of the digital audio signal is deteriorated.

  Correspondingly, the compact disc player obtains reproduction data from the compact disc in the same manner as the compact disc player according to the above-described embodiment, reproduces a digital audio signal from the reproduction data, and outputs it to an external device. At this time, the compact disc player recovers the sound quality of the digital audio signal by the bit operation unit 65 shown in FIG.

  That is, in the bit operation unit 65, the two-channel digital audio signals LM and LS reproduced from the compact disc are input to the comparison circuit 66, where the upper 8 bits of the digital audio signals LM and LS match. Judge.

  The arithmetic circuit 67 receives the two-channel digital audio signals LM and LS, multiplies the amplitude of the main digital audio signal LM by a factor of 2, and then subtracts it from the sub digital audio signal LS. As a result, the arithmetic circuit 67 causes the digital audio signal represented by (R−L) / 2 to overflow from 8 bits and the right digital audio signal R is assigned to the secondary digital audio signal LS. The digital audio signal representing the left channel L is reproduced. The arithmetic circuit 67 outputs the digital audio signal thus generated together with the sub digital audio signal LS.

  The arithmetic circuit 68 receives the two-channel digital audio signals LM and LS, and adds and subtracts these two digital audio signals LM and LS. Thus, the arithmetic circuit 67 represents the left channel L and the right channel R, respectively, when the digital audio signal represented by (R−L) / 2 is assigned to the lower 8 bits of the sub digital audio signal LS. Play a digital audio signal.

  The selection circuit 64 selects and outputs the two-channel digital audio signals output from the two arithmetic circuits 67 and 68 based on the comparison result SEL of the comparison circuit 66. That is, when the upper 8 bits of the digital audio signals LM and LS match, in this case, the lower 8 bits of the sub digital audio signal LS is assigned a digital audio signal represented by (RL) / 2. As a result, the digital audio signal output from the selection circuit 68 is selectively output. On the other hand, if the upper 8 bits of the digital audio signals LM and LS do not match, the right digital audio signal is assigned to the sub digital audio signal LS in this case. Selects and outputs a digital audio signal.

  The compact disc player outputs the digital audio signal whose quality has been recovered in the same manner as in the first embodiment.

  Even if the digital audio signal is manipulated between channels and the sound quality is deteriorated as in the ninth embodiment, the same effect as in the above-described embodiment can be obtained.

(10) Tenth Embodiment In this embodiment, the optical disc recording apparatus exposes the master disc 2 with a digital audio signal having deteriorated sound quality in the same manner as the optical disc recording apparatus 1 according to the above-described embodiment. Furthermore, the sound quality of the digital audio signal is degraded by manipulating bits between channels. This example is an example as a reference example of the present invention.

  At this time, in this embodiment, digital audio signals represented by (R + L) / 2 and (RL) / 2 are generated in the same manner as in the ninth embodiment. Further, of the two-channel digital audio signals, the digital audio signal represented by (R + L) / 2 is assigned to the conventional right and left channels and recorded. On the other hand, in the digital audio signal represented by (RL) / 2, since the data amount is small, the data is compressed, allocated to the subcode, and recorded on the master disc.

  As a result, the optical disk recording apparatus operates the digital audio signal between the channels to deteriorate the quality of the digital audio signal, and further allows the perceived deterioration of the quality and recovers the deteriorated quality.

  Correspondingly, the compact disc player obtains reproduction data from the compact disc in the same manner as the compact disc player according to the above-described embodiment, reproduces a digital audio signal from the reproduction data, and outputs it to an external device. At this time, the compact disc player sequentially calculates and processes the data represented by (RL) / 2 obtained from the subcode and the data represented by (R + L) / 2 reproduced as a digital audio signal. As a result, a 2-channel digital audio signal is reproduced and output.

  As in the tenth embodiment, the same effect as in the above-described embodiment can be obtained by operating the digital audio signal between the channels and transmitting the data necessary for restoring the sound quality by the subcode. .

(11) Eleventh Embodiment In this embodiment, as described above with reference to FIG. 9, the additional data recording area AR3 is formed between the lead-out area AR4 and the user area AR2. Further, in place of the subcode described in the tenth embodiment, a digital audio signal represented by (RL) / 2 is recorded in the additional data recording area AR3. This example is an example as a reference example of the present invention.

  Correspondingly, in the compact disc player, the user area AR2 and the additional data recording area AR3 are simultaneously accessed in parallel by two optical pickups. Alternatively, the user area AR2 and the additional data recording area AR3 are alternately accessed by repeatedly seeking one optical pickup, and reproduction data obtained from the areas AR2 and AR3 are buffered and output. Thereby, the compact disc player reproduces the compact disc so that the data represented by (R−L) / 2 and the data represented by (R + L) / 2 can be processed simultaneously in parallel. Further, the reproduced data represented by (R−L) / 2 and the data represented by (R + L) / 2 are sequentially processed, thereby reproducing and outputting a 2-channel digital audio signal.

  Even if the digital audio signal is manipulated between the channels as in the eleventh embodiment and the manipulated channels are individually transmitted, the same effect as in the above-described embodiment can be obtained.

(12) Other Embodiments In the first embodiment described above, the case where the bit operation is performed according to a certain rule in units of 2 bits is described. However, the present invention is not limited to this. For example, bit inversion is performed. When the bit operation is performed by the above, the present invention can be widely applied to the case where the bit operation is performed by replacing each bit of the lower 8 bits according to a predetermined rule.

  In the third embodiment described above, the sound quality of the digital audio signal is deteriorated by the key data which is the additional data, and the additional data is recorded on the outer peripheral side of the compact disc. However, the present invention is not limited to this. For example, data that transmits significant information related to the compact disc may be recorded, and the sound quality of the digital audio signal may be deteriorated by a logical operation between the data and the digital audio signal. In this case, as data for transmitting this kind of meaningful information, text data indicating the copyright holder, text data for lyrics, image data for jackets, HTML data for guiding related copyrighted works, etc. may be applied. it can.

  Correspondingly, in the compact disc player, information relating to the compact disc can be displayed by the data transmitting this significant information, and the sound quality can be recovered using this data. Further, in these cases, this significant data recorded on the outer peripheral side may be separately encrypted and recorded.

  In the fourth embodiment, the lower 8 bits of the 18-bit digital audio signal are compressed and synthesized with the upper 10 bits, thereby degrading the sound quality of the 18-bit digital audio signal. Although the case of recording has been described, the present invention is not limited to this. For example, a 20-bit digital audio signal is decomposed into a high-order 16-bit digital audio signal and a low-order 4-bit digital audio signal. Is recorded on the outer peripheral side of the compact disc, and the sound quality of the digital audio signal is degraded by a logical operation of the lower 4 bits of the 16-bit digital audio signal and the 4-bit digital audio signal recorded on the outer peripheral side. Also good. In this way, in a dedicated machine that reproduces the compact disc, it is possible to output a digital audio signal with higher sound quality by executing the processing corresponding to the processing with degraded sound quality.

  In many of the embodiments described above, the lower 8 bits of the digital audio signal have been bit-operated to degrade and restore the sound quality of the digital audio signal. However, the present invention is not limited to this. If necessary, the number of bits to be manipulated can be variously set to 6 bits, 4 bits, 2 bits, etc., and the same effect can be obtained even if only a predetermined bit of the digital audio signal is manipulated. Can do.

  Further, in the above-described embodiment, the case where the predetermined quality bit, which is a fixed ratio with respect to all the bits of the digital audio signal, is manipulated to deteriorate the sound quality and the deteriorated sound quality is recovered has been described. However, the number of bits to be operated may be changed according to the amplitude of the digital audio signal, for example, and thereby the degree of deterioration and the degree of recovery may be varied according to the digital audio signal. Alternatively, the number of bits to be manipulated may be changed by a time code or the like, thereby changing the degree of deterioration and the degree of recovery.

  Furthermore, in these cases, by changing the number of bits to be operated according to the peak value, dynamic range, frequency spectrum distribution, etc. of the digital audio signal, the degree of deterioration and the degree of recovery can be varied according to the digital audio signal. May be. In this way, it is possible to variously manipulate the audible sound quality deterioration that varies depending on the source.

  In these cases, the same effect can be obtained even if the number of bits to be operated is varied depending on the genre of the source. In other words, for example, a piano solo of a classical tune has a large dynamic range and the signal level is extremely lowered in a portion where the volume is low, and even if the number of bits to be manipulated is reduced, sound quality degradation can be perceived with certainty. it can. On the other hand, pops and the like are characterized by a relatively small dynamic range and a relatively small decrease in signal level even at a small volume. As a result, in pops and the like, the number of bits to be manipulated can be increased compared to piano solos and the like, and sound quality deterioration can be perceived to the same extent as in piano solos and the like.

  In the above-described embodiment, when the copyright can be surely protected, the sound quality is completely recovered and the digital audio signal is output. In other cases, the sound quality is not recovered at all. However, the present invention is not limited to this, and the degree of sound quality deterioration may be varied according to the external device. In other words, in this case, in the first embodiment described above, for example, when a digital audio signal is output to an external device using conventional SCMS, only 12 bits out of 16 bits are output with a correct digital value.

  In these cases, as shown in FIG. 12, for example, a device ID is obtained from an external device 70 connected by IEEE1394 or the like, and the sound quality of the digital audio signal is determined according to the external device by a bit operation based on the device ID. May be deteriorated. Incidentally, in this case, the bit operation unit 72 on the compact disc player 71 side performs bit operation by, for example, encryption so that the sound quality of the digital audio signal DM is deteriorated.

  On the other hand, in the external device 70, the recording system is configured so that the input digital audio signal can be recorded without any bit operation, and the quality of the digital audio signal is determined based on the device ID of the external device. A bit operation unit to be recovered is arranged in the reproduction system.

  In this way, the digital audio signal can be set to be played back with high sound quality only when played back by the external device 70, and only a private copy can be enjoyed with high sound quality. Thereby, illegal distribution of the recording medium copied by the external device 70 can be prevented.

  On the contrary, when the device ID acquired from the device to which the digital audio signal is sent is determined and the digital audio signal is output to a device such as a mini-disc device integrated with a compact disc player, for example. Only the sound quality of the digital audio signal is recovered and output.

  At this time, in this integrated device, the digital audio signal input with high sound quality is recorded with the sound quality deteriorated with reference to its own device ID, and the sound quality of the reproduced digital audio signal is recorded in its own device. Recover based on ID. In this way, only private copies can be enjoyed with high sound quality, and illegal distribution of copied recording media can be prevented.

  Further, in the above-described embodiment, the case where the sound quality is deteriorated for the digital audio signal recorded on the compact disc has been described. However, the present invention is not limited to this, and an optical disc device integrated with a recording / reproducing system, such as a mini disc device, It can be widely applied to digital audio tape recorders and the like. In this case, the sound quality is deteriorated and recovered not only when the digital audio signal is input / output to / from an external device but also when the digital audio signal is recorded on the recording medium. By performing the deterioration and recovery based on the device ID, serial number, etc. of each device, it is possible to remarkably restrict copying other than private purposes.

  Further, in the above-described embodiment, the case where the sound quality of the digital audio signal recorded on the compact disk is deteriorated has been described. However, the present invention is not limited to this, and the digital audio signal is transmitted via, for example, digital satellite broadcasting or the Internet. The present invention can be widely applied to such cases.

  In the above-described embodiment, the case of transmitting a digital audio signal has been described. However, the present invention is not limited to this, and can be widely applied to the transmission of various digital signals such as a digital video signal.

  The present invention relates to a digital signal transmission apparatus, a digital signal transmission method, and a digital signal recording medium, and can be applied to, for example, a compact disk and a compact disk recording / reproducing apparatus.

1 is a block diagram showing an optical disk recording apparatus according to a first embodiment of the present invention. 2 is a chart for explaining the operation of the optical disk recording apparatus of FIG. 1. 1 is a block diagram showing a compact disc player according to a first embodiment of the present invention. FIG. 4 is a chart for explaining the operation of the compact disc player in FIG. 3. FIG. It is a block diagram which shows the bit operation part applied to the optical disk recording device based on a 4th Example. It is a block diagram which shows the bit operation part applied to the compact disc player based on a 4th Example. It is a block diagram which shows the bit operation part applied to the optical disk recording device based on a 5th Example. It is a block diagram which shows the bit operation part applied to the compact disc player based on a 5th Example. It is a perspective view which shows the compact disk based on a 6th Example. It is a block diagram which shows the bit operation part applied to the optical disk recording device based on a 9th Example. It is a block diagram which shows the bit operation part applied to the compact disc player based on a 9th Example. It is a block diagram which shows the audio system which concerns on another Example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Optical disc recording device, 2 ... Disc master disc, 10, 28, 50, 52, 55, 57, 61, 65 ... Bit operation part, 20, 71 ... Compact disc player, 29 ... Disc discrimination | determination part, 33 …… External device identification unit

Claims (10)

Quality deterioration means for performing predetermined arithmetic processing between the digital signals of the respective channels of the input digital signal composed of digital signals of a plurality of channels to generate a digital signal of quality deterioration;
Transmission means for transmitting the digital signal of the quality degradation,
The quality deterioration means is
Arithmetic means for performing addition processing and subtraction processing between the digital signals of the channels and outputting a main signal and a subtraction signal;
When the subtraction signal can be expressed by only a plurality of lower bits, a combined signal in which the upper bits of the main signal and the lower bits of the subtraction signal are respectively assigned to the upper bits and lower bits is selected. A sub-signal that is output as a sub-signal, and when the subtraction signal is difficult to express with only a plurality of lower-order bits, the digital signal of the channel subjected to the subtraction processing is selected and output as the sub-signal.
An apparatus for transmitting a digital signal, wherein the main signal and the sub signal are output as the quality-degraded digital signal . The digital signal of the quality deterioration is
The quality of the input digital signal is restored by processing the main signal and the sub-signal based on the match / mismatch of the plurality of high-order bits of the main signal and the high-order bits of the sub signal
The digital signal transmission apparatus according to claim 1. The transmission means includes
The digital signal transmission apparatus according to claim 1, wherein the quality-degraded digital signal is recorded on an optical disc and the quality-degraded digital signal is transmitted. A predetermined arithmetic process is performed between the digital signals of each channel of the input digital signal consisting of a digital signal of a plurality of channels to generate a digital signal with degraded quality,
A digital signal transmission method for transmitting the quality-degraded digital signal,
An operation step of performing addition processing and subtraction processing between the digital signals of the channels to output a main signal and a subtraction signal;
When the subtraction signal can be expressed by only a plurality of lower bits, a combined signal in which the upper bits of the main signal and the lower bits of the subtraction signal are respectively assigned to the upper bits and lower bits is selected. A sub-signal, and when the subtraction signal is difficult to express with only a plurality of lower bits, the digital signal of the channel subjected to the subtraction processing is selected and output as the sub-signal,
A digital signal transmission method, wherein the main signal and the sub signal are output as the quality-degraded digital signal . The quality-degraded digital signal is:
The quality of the input digital signal is restored by processing the main signal and the sub-signal based on the match / mismatch of the plurality of high-order bits of the main signal and the high-order bits of the sub signal
5. A digital signal transmission method according to claim 4, wherein: 5. The digital signal transmission method according to claim 4 , wherein the quality-degraded digital signal is recorded on an optical disc and the quality-degraded digital signal is transmitted. Input a digital signal of quality deterioration that is subjected to predetermined arithmetic processing between the digital signals of the respective channels of the input digital signal consisting of digital signals of a plurality of channels and is deteriorated in quality from a predetermined transmission path,
A quality recovery step of recovering the quality of the quality-degraded digital signal by performing signal processing based on the predetermined arithmetic processing ;
The quality-degraded digital signal is:
It has a main signal and a sub signal,
The main signal is generated by the addition process between the digital signals of the channels,
When a subtraction signal by subtraction processing between the digital signals of the channels can be expressed by only a plurality of lower bits, the upper bits of the main signal and the lower bits of the subtraction signal are respectively represented by upper bits and lower bits. The composite signal assigned to is selected and the sub-signal is generated,
When the subtraction signal is difficult to express with only a plurality of lower bits, the digital signal of the channel subjected to the subtraction process is selected and the sub signal is generated,
The quality recovery step includes:
A step of comparing the upper bits of the main signal with the upper bits of the sub-signal;
Based on the comparison result of the comparison step, when the upper bits of the main signal match the upper bits of the sub signal, the addition process and subtraction process of the main signal and the sub signal are performed. A first processing step for generating a digital signal for each channel of the input digital signal;
Based on the comparison result of the comparison step, if the upper bits of the main signal do not match the upper bits of the sub signal, the sub signal is subtracted from the main signal to A digital signal transmission method comprising: a second processing step of generating a digital signal of one channel used for generation and setting the sub-signal to the digital signal of the other channel . The transmission path is
Having an optical disc,
The digital signal transmission method is:
The digital signal transmission method according to claim 7 , wherein the quality-degraded digital signal is reproduced from the optical disk, and the quality-degraded digital signal is input. Input a digital signal of quality deterioration that is subjected to predetermined arithmetic processing between the digital signals of the respective channels of the input digital signal consisting of digital signals of a plurality of channels and is deteriorated in quality from a predetermined transmission path,
In the digital signal transmission apparatus for recovering the quality of the quality-degraded digital signal by performing signal processing based on the predetermined arithmetic processing,
The quality-degraded digital signal is:
It has a main signal and a sub signal,
The main signal is generated by the addition process between the digital signals of the channels,
When a subtraction signal by subtraction processing between the digital signals of the channels can be expressed by only a plurality of lower bits, the upper bits of the main signal and the lower bits of the subtraction signal are respectively represented by upper bits and lower bits. The composite signal assigned to is selected and the sub-signal is generated,
When the subtraction signal is difficult to express with only a plurality of lower bits, the digital signal of the channel subjected to the subtraction process is selected and the sub signal is generated,
The transmission apparatus is
A comparison unit that compares a plurality of upper bits of the main signal with a plurality of upper bits of the sub-signal;
Based on the comparison result of the comparison unit, when the plurality of upper bits of the main signal and the plurality of upper bits of the sub signal match, the addition process and subtraction process of the main signal and the sub signal cause the A first arithmetic processing unit for generating a digital signal of each channel of the input digital signal;
Based on the comparison result of the comparison unit, when the upper bits of the main signal do not match the upper bits of the sub signal, the main signal is generated by subtracting the sub signal from the main signal. And a second arithmetic processing unit for setting the sub-signal to the digital signal of the other channel.
A digital signal transmission device. The transmission path is
Having an optical disc,
The digital signal transmission device comprises:
A reproduction unit that reproduces the quality-degraded digital signal from the optical disc;
The digital signal transmission apparatus according to claim 9.

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