JPH0955026A - Recording medium, recording device and reproducing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a second generation CD and the corresponding recording and reproducing devices by considering an interchangeability with respect to a first generation CD and resolving incompatible points. SOLUTION: As recording media (CD), there exist a first generation CD1a having a sampling frequency of 44.1KHz and a second generation CD1b having a sampling frequency of 2.8224MHz (64 times the first generation CD: a multiple of an integer). In the recording device for a second generation CD, original audio signals, i.e., analog audio signals are inputted to a terminal 10 from a master tape and digital audio (DO) signals are outputted by a ΔΣ modulation one bit A/D converter 11. The DO signals are supplied to a recording signal processing section 17 and modulated to form recording signals. The recording signals are supplied to a disk recorder 18, pits are formed to a disk master disk to generate a master disk CD for second generation CD music software. For the case of the CD1a, the output from the converter 11 is fed to decimation filters 12 and 13 and a bit mapping section 14 to generate a master disk CD for first generation CD music software.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recording medium having a novel data format, and a recording device and a reproducing device corresponding to the recording medium.

[0002]

2. Description of the Related Art CDs (Compact Discs), which are now widespread as high-quality recording media, are those on which digital audio data having a sampling frequency fs = 44.1 KHz and a quantization bit number = 16 bits is recorded. ing. By the way, along with the realization of various media with large capacity / high transfer rate in recent years, a system that realizes higher sound quality for such a CD (hereinafter, referred to as a first-generation CD) has been studied. However, in order to achieve high sound quality, the first consideration is to raise the sampling frequency.

That is, assuming that the sampling frequency fs = 44.1 KHz as in the case of the first generation CD, the audio signal data is limited to the components of the frequency band up to about 20 KHz, but the sampling frequency is set to a higher frequency. It is intended to realize recording / reproducing of voice more faithful to natural sound by enabling recording of voice data components of 20 KHz or more.

[0004]

Although it is possible to construct a new CD media system with a data format in which the sampling frequency is higher than that of the first generation CD, there are various problems in practical use. Even if a new type CD media system is realized, practically, compatibility with the first generation CD is required.

For example, a reproducing apparatus compatible with a new type CD by a data format having a high sampling frequency is required to be able to reproduce a first generation CD.
In the case where the disc compatibility is added to the reproducing apparatus as described above, a digital decoder such as a decoder and a D / A converter corresponding to the first generation CD and a decoder and a D / A converter corresponding to the new method CD are eventually used. In the area, two reproduction system circuits are required. Of course, the clock generator must be prepared separately for each circuit system. This is not appropriate because it complicates the circuit configuration of the reproducing device, increases the size, and increases the cost.

Here, in order to reduce the circuit scale, for example, 2
When an attempt is made to share the D / A converter in the reproduction system circuits of the system, the sampling frequencies of the data supplied from both reproduction system circuits must match at the stage of input to the D / A converter. That is, a sampling rate converter must be provided in one or both circuit systems to convert the sampling frequency into a required frequency.

However, there is a problem in that jitter occurs due to the limit of time resolution in the sampling rate converter, which causes deterioration of sound quality. For example, if the sampling frequency of the new type CD is 96 KHz, the sampling rate converter sets the sampling frequency to 96 KHz for the output of the first generation CD decoder (sampling frequency fs = 44.1 KHz). / A converter is 1
However, due to the jitter that occurs when converting from 44.1 KHz to 96 KHz, such a reproducing device causes deterioration of the sound quality of the first-generation CD.

There is also a problem on the CD manufacturing side.
For example, considering that both a new method CD and a first-generation CD are produced from a certain sound source (master tape of music, etc.),
The audio signal from the master tape for the new system CD,
For example, the sampling frequency will be 96 KHz and will be converted into digital data. Therefore, high quality sound is realized for the new system CD, but for the first generation CD produced at the same time, the digital data of sampling frequency 96KHz must be converted into the digital data of sampling frequency 44.1KHz. At this time, the sound quality is deteriorated due to the jitter generated in the sampling rate converter process.

[0009]

In view of these problems, the present invention solves the disadvantages of taking into account the compatibility with the first-generation recording medium, and a new type of recording medium. , And a recording device and a reproducing device corresponding thereto.

That is, as the recording medium, a frequency of n times 44.1 KHz (where n is an integer) is used as a sampling frequency so that an audio signal converted into digital data is recorded. The audio signal converted into digital data may be a 1-bit ΔΣ-modulated signal.

As the recording device, a digital audio signal generating means for converting an analog audio signal into a digital audio signal using a sampling frequency which is n times 44.1 KHz (where n is an integer), and the digital audio signal generating means A recording unit capable of performing a required recording signal process on the generated digital audio signal and recording the signal on a recording medium is provided, and the recording medium can be generated. Further, the digital audio signal generated by the digital audio signal generating means is subjected to a decimation process with a sampling frequency of 1 / n to generate a digital audio signal having a sampling frequency of 44.1 KHz, and the filter means. By providing the second recording means capable of performing the required recording signal processing on the digital audio signal obtained by the above and recording it on the recording medium, the first generation recording medium having a sampling frequency of 44.1 KHz can be also used. Make it possible to create without deterioration of sound quality.

As a reproducing apparatus, a clock generating means for generating a clock having a predetermined frequency and a clock output from the clock generating means for the information read from the recording medium are used to multiply 44.1 KHz by n times (however, Decoding means for extracting a digital audio signal with a sampling frequency of (n is an integer) and D / A conversion means for converting the digital audio signal obtained by this decoding means into an analog signal are provided, and the recording medium is compatible with the above recording medium. Realize the device. Further, a frequency dividing means for dividing the clock from the clock generating means to obtain a second clock, and a digital audio with a sampling frequency of 44.1 KHz using the second clock for the information read from the recording medium. By providing the second decoding means for extracting the signal, compatibility with the first generation recording medium can be obtained without causing a significant increase in the circuit scale.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to FIGS. Here, as a recording medium as an example of the embodiment, a sampling frequency fs = 44.1
It achieves higher sound quality than the first-generation CD, which has a KHz and 16-bit quantization bit rate, and has a sampling frequency of 64 times that of the first-generation CD, 2.8224 MHz.
(Hereafter, “fs” is 44.1KHz, and 2.8224MHz is “64
fs ”), and a digital audio signal to be recorded is a signal obtained by subjecting the digital audio signal of 64 fs sampling to 1-bit ΔΣ modulation.
Hereinafter, such a recording medium (CD) is referred to as a second generation CD.

As is well known, it is possible to set the sampling frequency of the 1-bit ΔΣ-modulated signal to be remarkably high for the data capacity or the data transfer rate as compared with the conventional PCM-modulated signal. Therefore, in the present embodiment, the sampling frequency is set to 64 fs, and in principle, even high frequency components up to 1.4 MHz can be recorded and reproduced as data. As a result, a second-generation CD whose sound quality is dramatically improved compared to the first-generation CD is provided. The sampling frequency of the second-generation CD is set to be an integral multiple of the sampling frequency of the first-generation CD, so that consistency with the first-generation CD system is ensured and compatibility is not maintained. I try not to occur.

First, a recording apparatus compatible with the second generation CD will be described with reference to FIGS. FIG. 1 is a block diagram of a recording apparatus. This recording apparatus is capable of producing a first generation CD as well as producing a second generation CD. An analog audio signal as an original audio signal from the master tape is input to the terminal 10. The frequency spectrum of the analog audio signal is as shown in FIG.

This analog audio signal is converted into digital data by the ΔΣ modulation 1-bit A / D converter 11. At this time, the sampling frequency is 64 fs, and a digital audio signal of 64 fs / 1 bit format is output. The frequency spectrum of this 64fs / 1-bit digital audio signal is shown in Fig. 2 (b).
become that way. In other words, in principle, data in the frequency band up to 32 fs can be digitized.
Almost all the components of the analog audio signal shown in (a) are left as digital data. In addition, due to the noise shaping function in the ΔΣ modulation, the quantization noise component is in a state of being collected on the high frequency side on the frequency axis.

The 64 fs / 1-bit digital audio signal is supplied to the recording signal processing section 17 and is directly modulated into a recording signal. That is, the 64 fs / 1-bit signal is used as it is as the recorded digital audio data. The recording signal processing unit 17 executes recording modulation processing such as addition of an error correction code and EFM modulation, and a signal corresponding to the pit information actually formed on the disc is generated as a recording signal.

This recording signal is supplied to the disk recorder 18, and the recording operation based on the recording signal, that is, the pit forming operation on the disk master is performed, and the second generation C
An original CD of music software as D1b is created. A stamper is formed from the master CD thus created, and the actual second-generation CD 1b is mass-produced.

As the same music software, the first generation C
To create D, ΔΣ modulation 1-bit A / D converter 1
The 64 fs / 1 bit signal output from 1 is first supplied to the decimation filter 12 and then 2 fs (= 88.2).
KHz) / 24-bit digital data. 2fs
The frequency spectrum of / 24-bit digital data is as shown in FIG. That is, since the sampling frequency is set to 2fs, the data component of the frequency band up to the frequency fs is left.

Further, in the decimation filter 13, f
It is s (= 44.1KHz) / 24-bit digital data. The frequency spectrum of the fs / 24-bit digital data is as shown in FIG. 2D, and data components in the frequency band up to (1/2) fs are left.

The decimation filters 12 and 13 set the sampling frequency to 1/64, but this is not a so-called sampling rate conversion but a completely synchronous digital filter for performing decimation of 64: 1. There is no element that causes a jitter component.

This fs / 24-bit digital data has a quantization bit number of 16 by the bit mapping unit 14.
It is converted into bit data and supplied to the recording signal processing unit 15. The recording signal processing unit 15 adds an error correction code to the fs / 16-bit digital audio signal,
A recording signal is generated by performing necessary processing such as EFM modulation, and is supplied to the disc recorder 16. The disc recorder 16 forms pits on the disc master on the basis of the recording signal, and the master CD of the music software as the first generation CD 1a is created. A stamper is formed from the master CD thus created, and the actual first-generation CD 1a
Will be mass-produced.

As described above, in the recording apparatus of FIG. 1, the first generation C
It is possible to create the D1a and the second generation CD1b. Here, by using the digital audio data of 64 fs / 1 bit as the recording signal as it is as the second generation CD, the second generation CD 1b becomes a disc which achieves a dramatically high sound quality.

Further, since the sampling frequency of the second-generation CD 1b is set to an integral multiple of that of the first-generation CD, the sound quality of the created first-generation CD 1a is not deteriorated as compared with the conventional case. That is, for the conversion of the sampling frequency, a filtering process for performing 1/64 decimation is sufficient, and since the sampling rate converter is not necessary, the jitter due to the rate conversion does not occur. It is possible to obtain the same sound quality as when directly sampling at 44.1 KHz.

Next, a reproducing apparatus compatible with the second generation CD 1b will be described. FIG. 3 is a block diagram of a main part of the reproducing apparatus. It should be noted that this reproducing apparatus is also capable of reproducing the first-generation CD 1a.

The disk 1 (first generation CD 1a or second generation CD 1b) is rotationally driven by a spindle motor 26. The spindle motor 26 is driven at CLV (constant linear velocity) by a drive signal from the motor controller 25.

The spindle servo operation for CLV control by the motor controller 25 will not be described in detail, but the clock CK2 from the oscillator 23 is divided by the frequency divider 24.
The frequency is divided by to obtain a predetermined reference clock CKs, and this reference clock CKs is compared with the PLL system clock synchronized with the reproduced data to generate an error signal. Then, CLV servo is executed by applying electric power to the spindle motor 26 according to the error signal. Although the PLL system clock is not shown, it is generated by injecting the extracted data into the PLL circuit in the first generation CD decoder 28 and the second generation CD decoder 29, for example.

As the disc 1 is rotated and the pickup 21 irradiates the recording surface of the disc 1 with a laser beam and detects the reflected light, information by the pits formed on the disc 1 is read. The information read by the pickup 21 is supplied to the first generation CD decoder 28 and the second generation CD decoder 29.

From the oscillator 23, a clock CK having a frequency used for decoding in the second generation CD decoder 29
2 is generated, and this is the second generation CD decoder 29.
Is supplied to. In addition, the clock CK from the oscillator 23
2 is set by the frequency divider 27 as a clock CK1 having a frequency used for decoding in the first generation CD decoder 28,
It is supplied to the first generation CD decoder 28. 2nd generation CD
The decoder 29 decodes and outputs a sampling frequency of 64 fs and a 1-bit digital audio signal, and supplies the decoded audio signal to the T ₂ terminal of the switch 32.

A 16-bit digital audio signal with a sampling frequency of fs is decoded and output from the first-generation CD decoder 28. The oversampling digital filter 30 and the ΔΣ modulation circuit 31 provide a sampling frequency of 64 fs and a 1-bit digital signal. It is regarded as an audio signal. Then, it is supplied to the T ₁ terminal of the switch 32.

The output of the switch 32 is supplied to the 1-bit D / A converter 33, converted into an analog audio signal, and output from the terminal 34. The 1-bit D / A converter 33 is supplied with the clock CK2 from the oscillator 23, that is, the same clock as the clock for the second generation CD decoder 29.

The disc discriminating unit 22 determines whether the mounted disc 1 is the first generation CD 1a or the second generation CD 1b.
It becomes the part which determines whether or not. This determination can be made by reading the TOC data recorded on the innermost side of the disc. The disk discriminating unit 22 controls the frequency division ratio of the switch 32 and the frequency divider 24 according to the discrimination result.

The operation of such a reproducing apparatus will be described. First, consider a case where the disc 1 to be reproduced is a second generation CD 1b. First, when the disc discriminating unit 22 discriminates from the TOC data of the disc 1 that the disc is the second generation CD 1b, the frequency division ratio in the frequency divider 24 is set to the second generation CD.
Set to a value corresponding to 1b. Also, switch 32 to T ₂
Connect to the terminal.

The frequency division ratio of the frequency divider 24 is the second generation CD.
By setting the value corresponding to 1b, the frequency of the reference clock CKs used for the CLV servo in the motor controller 25 becomes the frequency corresponding to the second generation CD 1b. That is, the disc 1 is rotationally driven at a linear velocity corresponding to the second-generation CD 1b. Pickup 21 at this time
The pit information extracted by is the second generation CD decoder 2
By being decoded by 9, the digital audio signal of 64fs / 1 bit is decoded. At this time, since the switch 32 is connected to the T ₂ terminal, 6
The 4 fs / 1-bit digital audio signal is supplied to the 1-bit D / A converter 33 and converted into an analog audio signal.

Next, the disc 1 to be reproduced is the first generation C
Consider the case of D1a. First the TO of disk 1
If the disc discriminating unit 22 discriminates from the C data that the disc is the first generation CD 1a, the frequency division ratio in the frequency divider 24 is set to a value corresponding to the first generation CD 1a. Further, the switch 32 is connected to the T ₁ terminal.

The frequency division ratio of the frequency divider 24 is the first generation CD.
By setting the value corresponding to 1a, the frequency of the reference clock CKs used for the CLV servo in the motor controller 25 becomes the frequency corresponding to the first-generation CD 1a. That is, the disc 1 is rotationally driven at the linear velocity corresponding to the first-generation CD 1a. Pickup 21 at this time
The pit information extracted by the 1st generation CD decoder 2
The fs / 16-bit digital audio signal is decoded by being decoded by 8. This f
The s / 16-bit digital audio signal is an oversampling filter 3 operated by the clock CK2.
The 0 and ΔΣ modulation circuit 31 produces a digital audio signal of 64 fs / 1 bit. Since the switch 32 is connected to the T ₁ terminal, the 64 fs / 1-bit digital audio signal is transferred to the 1-bit D / A converter 3
3 and is converted into an analog audio signal.

According to such a reproducing apparatus, the second generation C
By reproducing D1b, it is possible to reproduce very high-quality sound data at 64fs. Also,
The sampling frequency of the second-generation CD 1b is the first-generation CD
Since the sampling frequency is set to an integral multiple of 1a, as shown in FIG. 3, it is possible to realize a reproducing apparatus having compatibility without having a complicated structure for the clock system and the reproducing system.

That is, first, regarding the clock system, the first
Since the sampling frequency ratio between the generation CD 1a and the second generation CD 1b is an integer ratio, the oscillator 23
The clock output from can be shared. That is, even if a plurality of oscillators are not provided, the frequency divider can easily generate a clock having a required frequency. As a result, it is not necessary to construct two master clock systems independent of each other, and the circuit configuration of the clock system can be simplified.

As for the reproducing system, 1-bit D / A
Since the converter 33 can be shared, the reproduction system circuit can also have a simple structure, and at the same time, sound quality deterioration does not occur. Since the 1-bit D / A converter 33 is a D / A converter that performs an operation corresponding to the reproduction data from the second-generation CD 1b, there is no problem with the second-generation CD 1b, but
In order to use it for playback data from the generation CD 1a,
The fs / 16-bit data from the first generation CD decoder 28 must be converted to 64fs / 1-bit data. However, also with respect to this, since the sampling frequency is an integral multiple, oversampling by 64 times by the oversampling filter 30 and conversion into 1 bit by the ΔΣ modulation circuit 31 are sufficient, and a sampling rate converter is not required. Since there is no cause of jitter generation, the sound quality of the first-generation CD 1a does not deteriorate.

FIG. 4 shows another structural example of the reproducing apparatus. It should be noted that the same functional parts as those in FIG. In this case, the D / A converter 36 operates with the clock CK ₁ , and the sampling frequency fs
It is supposed to correspond. Therefore, when the first-generation CD 1a is reproduced, the fs / 16-bit reproduction data output from the first-generation CD decoder 28 is directly supplied to the D / A converter 36 via the switch 32. ,
It is regarded as analog voice data.

On the other hand, when the second generation CD 1b is reproduced, 64 fs output from the second generation CD decoder 29.
The 1-bit reproduction data is the decimation filter 3
The decimation process of 64: 1 is performed by 5 and f
It is converted to s / 16-bit reproduction data. Then, it is supplied to the A / D converter 36 via the switch 32 to be converted into analog audio data.

In this case as well, similar to the reproducing apparatus of FIG. 3, compatibility can be realized by a simple clock system / reproducing system, and sound quality is not deteriorated by sharing the D / A converter 36. That is, there is no room for a jitter component in the processing by the decimation filter 35.

In the embodiment, the current CD system is the first-generation CD 1a, and the second-generation CD 1b, which is compatible with the first-generation CD 1a, has been described.
The present invention can be adopted even if it is not a D system. For example, in a digital tape recorder system, it is possible to realize a recording / reproducing system that employs a sampling frequency that is an integral multiple of 44.1 KHz.

The sampling frequency is 32 KHz, 4
The present invention is applied to a recording / reproducing system which is set to 8 KHz, and the sampling frequency is 32 KHz.n or 48 KH.
It is also possible to build a system such that z · n (where n is an integer). 48KH especially for video recording / playback
It may be possible that the sampling frequency of z · n is suitable for next-generation media.

[0045]

As described above, according to the present invention, there are provided a recording medium for recording digital audio data having a sampling frequency of n times 44.1 KHz (where n is an integer), and a recording device and a reproducing device corresponding thereto. It is provided, and high sound quality can be realized by increasing the sampling frequency in this way. In particular, by performing the ΔΣ modulation with 1 bit on the recorded data, it becomes possible to set the sampling frequency to a higher frequency, and the sound quality is sufficiently improved.

Further, by setting the sampling frequency to an integral multiple of 44.1 KHz adopted in the current CD system or the like, the compatibility with the current system is good. In particular, considering the compatibility between the recording medium of the present invention and the current recording medium, the sampling frequency is an integer ratio,
Compatibility can be realized without complicating the circuit configuration as a reproducing device. Moreover, since a sampling rate converter is not necessary, sound quality deterioration due to jitter does not occur. Similarly, both the recording medium of the present invention and the existing recording medium can be easily produced with respect to the same sound source in a state where the recording apparatus has good compatibility and there is no deterioration in sound quality due to jitter.

[Brief description of drawings]

FIG. 1 is a block diagram of a recording apparatus according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram of a frequency spectrum of a signal at each stage in the recording apparatus of the embodiment.

FIG. 3 is a block diagram of a playback device according to an embodiment of the present invention.

FIG. 4 is a block diagram of another reproducing apparatus according to the embodiment of the present invention.

[Explanation of symbols]

 1 disc 1a 1st generation CD 1b 2nd generation CD 11 ΔΣ modulation 1-bit A / D converter 12, 13, 35 decimation filter 15, 17 recording signal processing unit 14 bit mapping 16, 18 disc recorder 21 pickup 22 disc discriminating unit 23 Oscillator 24, 27 Frequency Divider 25 Motor Controller 26 Spindle Motor 28 First Generation CD Decoder 29 Second Generation CD Decoder 30 Oversampling Filter 31 ΔΣ Modulation Circuit 32 Switch 33 1 Bit D / A Converter 36 D / A Converter

Claims (6)

[Claims] 1. An n of 44.1 KHz as a sampling frequency
A recording medium characterized in that an audio signal converted into digital data is recorded by using a frequency of twice (where n is an integer). 2. The recording medium according to claim 1, wherein the audio signal converted into digital data is a 1-bit ΔΣ-modulated signal. 3. An analog audio signal is transmitted at n of 44.1 KHz.
Digital audio signal generating means for converting the digital audio signal into a digital audio signal by using a sampling frequency that is doubled (where n is an integer), and a required recording signal processing is performed on the digital audio signal generated by the digital audio signal generating means. A recording device capable of recording on a recording medium by means of a recording device. 4. A filter means for performing decimation processing with a sampling frequency of 1 / n on the digital audio signal generated by the digital audio signal generating means to generate a digital audio signal with a sampling frequency of 44.1 KHz. 4. The second recording means capable of performing required recording signal processing on the digital audio signal obtained by the filter means and recording the signal on a recording medium. Recording device. 5. A clock generating means for generating a clock of a predetermined frequency, and for information read from a recording medium, a clock output from the clock generating means is used to generate an n of 44.1 KHz.
A decoding means for extracting a digital audio signal with a sampling frequency of double (where n is an integer), and a D / A conversion means for converting the digital audio signal obtained by the decoding means into an analog signal are configured. A playback device characterized by the above. 6. A frequency dividing means for dividing a clock from the clock generating means to obtain a second clock, and 44.1 KHz using the second clock for information read from a recording medium. 6. The reproducing apparatus according to claim 5, further comprising: a second decoding unit that extracts a digital audio signal at the sampling frequency of.