JPH07334937A - Data recording method and disk medium - Google Patents

Abstract

PURPOSE:To lessen the deterioration in sound quality by a non-correctable error by determining the disk size to be a size similar to the side of a CD exclusive of its outside diameter and adopting a CD-ROM mode 2 formal as a physical format. CONSTITUTION:An MDCT section 31 is inserted between a band dividing filter 30 and a normalizing section 32 on the encoder side. Similarly, an IMDCT (reverse DCT) section 47 is inserted between a reverse normalizing section 46 an a band synthesizing filter 48 on the decoder side. As a result, the frequency resolution of processing is improve. The sound quality is better as the layer is higher in a Layer 1, a Layer 2 and a Layer 3, but on the contrary, the necessary computation quantity increases and a hardware scale increases. Accordingly, arrangement is made so that the Layer adequate for an application is selected. In this case, the data format complies with an MPEG 2. Accordingly, this method and medium are extremely convenient in the case of transmission of the data by communication circuits, etc.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a data recording method and a disk medium (hereinafter simply referred to as "disk") for recording a digital audio signal by a high efficiency coding method.

[0002]

BACKGROUND ART Currently, as a system for recording high-fidelity audio data on a storage medium (medium) such as a disk or a tape, a CD (Compact Disc
c), DAT (Digital Audio Tape recorder), and those using high-efficiency coding, MD (Mini Disc)
And DCC (Digital Compact Cassette). Table 1 shows the sampling frequency fS, the coding method, and the data transmission rate DTR in each system.

[0003]

[Table 1]

In any of these systems, the reproduction frequency bandwidth is in the range of 16 kHz to 24 kHz, and the reproduction S / N of CD and DAT is about 96 dB (except fs = 32 kHz of DAT). Also, M
For D and DCC, a high-efficiency coding method is used, and although the data transfer rate is a fraction of that of CD and DAT, the sound quality may be considered to be almost equivalent to those of CD and DAT. .

[0005]

However, the above background art has the following problems. (1) Both ATRAC, which is the MD encoding method, and PASC, which is the DCC encoding method, are both MPEG (Motion
Picture Image Coding Experts Group) is not an international standard format, but a proprietary format by the proposing organization. Therefore, it cannot be said that it is very suitable for data transmission in the future through a communication line or the like. For communication, standard and general formats are preferred whenever possible.

(2) The MD and DCC are not compatible with the CD even in the physical format of the medium. For this reason, it is difficult to design a playback device that is common with the CD players that are widely used at present. Even if a DCC whose type of medium is completely different from that of a CD is used, it is very convenient in practice if an apparatus can be designed so that it can be commonly recorded or reproduced on a disk.

(3) MD and DCC are CIRC (Cross Interleave) similar to CD and DAT as an error correction method.
d Reed-solomon Code: Double Reed-Solomon code) is used for C1 and C2 correction. However, MD,
In the DCC, as described above, ATRAC, P
A high efficiency coding method such as ASC is adopted. In the case of high-efficiency coded data, the weight per data bit is larger than that in the case of PCM coded data such as CD and DAT, and it is difficult to interpolate the data when uncorrectable.

Nevertheless, since the same error correction system as that for CDs and the like is used, the sound quality when error correction is impossible may be worse than that of CD.
From this point of view, in the case of the high-efficiency coding system, a more powerful error correction system commensurate with it is preferable.

(4) CD, DAT, D in background art
The high frequency reproduction limit of the audio frequency in each of the CC and MD systems is 24 kHz at the maximum. This corresponds to that it is generally said that a high tone of 20 kHz or more cannot be heard due to human auditory characteristics. However, recent studies have reported that sounds with a high frequency of 20 kHz or higher have a relaxation effect, which has been confirmed experimentally. From this point of view, the higher the high frequency reproduction limit of frequency, the better.

The present invention focuses on these points, and an object thereof is to record audio data based on a data format suitable for data transmission by a communication line. Another object is to make it possible to design a recording / reproducing apparatus that is highly compatible with a CD system and is practically excellent. Still another object is to reduce sound quality deterioration due to uncorrectable errors. Yet another purpose is
It is to improve the sound quality by obtaining the high frequency reproduction limit of high audio frequency.

[0011]

In order to achieve the above object, the data recording method of the present invention is a CD-ROM m.
Conforming to ode2form1, EDC, E in the format
Physical format using CC for third correction of CIRC; MPEG Audio-compliant data format in standard mode; MPEG Aud in high-quality mode
According to io, data is recorded in a data format in which the sampling frequency is set to a value exceeding 48 kHz. In addition, MPEG Audio includes Layer1, Layer2, Layer
There is er3, and either one is used. Further, the disk medium of the present invention has the same physical size as the current CD except for the outer diameter.

According to the present invention, the physical size of the disc excluding the outer diameter is the same as that of the CD, and the CD-ROM mode2 f
By adopting orm1, compatibility with the CD system is secured. Also, EDC of CD-ROM mode2 form1,
By performing the third correction by the ECC, the deterioration of the sound quality due to the high efficiency encoding is avoided. Furthermore, MPEG Aud
The io-compliant data format is convenient for data transmission via communication lines, and the high-frequency reproduction limit is increased by using a mode with a high sampling frequency.

The main aspects of the present invention are as follows. A disk medium on which data is written using phase change. A disk medium in which the recording time in standard mode and the recording time in high-quality mode are integer ratios, especially 2: 1. A disk medium whose sampling frequency in high-quality sound mode is 64 kHz. The above and other objects, features of the present invention,
Advantages will be apparent from the following detailed description and the accompanying drawings.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Although there may be many embodiments of the data recording method and disk medium of the present invention, a suitable number of embodiments will be shown and described in detail here. <Disk Size> First, the disk size of this embodiment will be described with reference to FIGS.
In this embodiment, the disc size is the same as that of the current CD except the disc outer diameter. The dimensions of each part of the disk are shown in Table 2 below.

[0015]

[Table 2]

In FIG. 1, these dimensions are shown corresponding to the disk cross section. As shown in the figure, the diameter of the disc center hole DH is 15 mm and the disc outer diameter is 70 mm, and the reproduction time is about 74 minutes. Further, the maximum diameter of the program area (data area) WP is 66 mm, and the diameter of the lead-out area is 68 mm, corresponding to this outer diameter. The lead-in area WI is inside the program area WP, and the lead-out area WO is outside.

In FIG. 2, the disk of this embodiment is the current C
It is shown in comparison with D and MD. The largest disc 10 is the current CD and has an outer diameter of 120 mm. The next largest disc 12 is a CD single with an outer diameter of 80
mm. The one shown in a square is the MD cartridge 14
Is. The outer diameter of the internal disk of the MD cartridge 14 is 64 mm for a read-only disk and 64.8 mm for a recording / playback disk. The disk 16 having an outer diameter of 70 mm in this embodiment has a size corresponding to the MD cartridge 14.

A CD 10 having an outer diameter of 120 mm and an outer diameter of 8
As is clear from the fact that the 0 mm CD single 12 can be reproduced by the same reproducing device, the outer diameter of the disc does not matter so much in the CD reproducing device. As described above, the disc of this embodiment has the same size as the existing CD except for the outer diameter, and therefore has good compatibility with the CD. Therefore, it is possible to design a reproducing device common to the CD player.

<Physical Format of Disk> Next, the physical format of the disk will be described with reference to FIG. In this embodiment, the physical format is
"CD-ROM X specified in ISO 9660
A: CD-ROM mode2 form1 "is used. In addition,
ISO is the International Organization for Standardiza
tion (International Organization for Standardization).

FIG. 3 shows this CD-ROM mode2 form1.
Sector formats are shown. The whole sector is
It is 2,352 bytes. At the beginning, 12-byte synchronization data (displayed as SYNC) is provided. Following the synchronization data is a 4-byte header. This header information includes 1-byte minute, 1-byte second, 1-byte sector address information, and 1-byte mode information. The mode information is information indicating the mode of the sector format of the CD-ROM. The header is followed by a sub-header of 8 bytes and user data of 2,048 bytes.

Next to the user data, 4 bytes of EDC
(Error-Detecting Code), 276 bytes of ECC (Er
ror Correcting Code) is located. As this ECC, RSPC (Reed-solomon Product-like Code) is used and includes 172 bytes of P-parity (row check byte) and 104 bytes of Q-parity (column check byte).

By the way, in this embodiment, the CIRC C
1 correction, C2 correction, and E at the end of the format
The third correction is performed using DC and ECC, which improves the correction capability. For this reason, even if high-efficiency coding such as MD and DCC is performed, error correction can be performed well, and it is possible to secure sound quality almost equal to that of a CD or the like.

<Disk Data Format> Next,
The data format of the disc of this embodiment is ISO
It conforms to 11172 MPEG Audio. This M
According to PEG Audio, the signal is divided into a number of subbands and processed.

FIGS. 4 and 5 show the MPEG Audio Layer.
Block diagrams of encoders and decoders for Layer 1 and Layer 2 are shown respectively. The difference between Layer1 and Layer2 is the number of audio samples per frame.
4 ”and Layer 2 are“ 1152 ”. First, the encoder of FIG. 4 will be described. PCM (Pulse-Code Modulatio
The audio signal modulated by n) is supplied on the one hand to a band-splitting filter 30 where it is divided into 32 sub-bands sb00, sb01, ..., Sb30, sb31.
Each sub-band component is supplied to the quantizing unit 34 after being normalized by the normalizing unit 32.

On the other hand, the PCM input is the psychoacoustic analysis unit 36.
, Where a masking curve based on auditory characteristics is calculated and a minimum audible limit is calculated. This technique is known as an information compression technique in ATRAC and PASC. The adaptive bit allocation unit 38 is for performing adaptive bit allocation based on the analysis result of the psychoacoustic analysis unit 36. Based on the bit allocation by this, an appropriate bit allocation for each subband in the quantization unit 34 is performed. Data is quantized. Multiplexer (M
In PX 40, the quantized data (main information) supplied from the quantizer 34 and auxiliary information such as the number of allocated bits are multiplexed. The multiplexed bit stream of information is recorded in the user data area in the sector format shown in FIG.

Next, the decoder of FIG. 5 will be described. The bit stream read from the disc is supplied to a demultiplexer (DMPX and shown) 42, where the processing opposite to the multiplexing is performed. The main information and the auxiliary information of each sub-band obtained by this are the inverse quantization unit 44.
, Where the main information is dequantized. The main information after the dequantization is supplied to the denormalization unit 46 together with the auxiliary information, where the main information is denormalized. The denormalized data of each subband is supplied to the band synthesis filter 48, where the data of each subband is band synthesized. In this way, a PCM audio signal is obtained from the disc.

The basic operation of Layer3 is also Layer1 and La.
Same as yer2, but sub-band component is further MDCT
The data transformed into the frequency domain by (Modified Discrete Cosine Transform) is normalized / quantized. As the processing block, on the encoder side, the MD shown in FIG. 6A is provided between the band division filter 30 and the normalization unit 32 in FIG.
The CT unit 31 is inserted. Similarly, on the decoder side, between the denormalization unit 46 and the band synthesis filter 48 of FIG.
The IMDCT (inverse MDCT) unit 47 shown in (B) is inserted. This improves the frequency resolution of the process. La
For yer1, Layer2, and Layer3, the higher the layer, the better the sound quality, but conversely, the required amount of calculation increases and the hardware scale increases. Therefore, be sure to select an appropriate layer for the application.

As described above, according to this embodiment, the data format is the international standard format MPEG.
Compliant with Audio Layer 2. Therefore, it is extremely convenient when data is transmitted through a communication line or the like.

<High Frequency Reproduction Limit of Audio Signal> Next, the high frequency reproduction limit of the frequency of the audio signal in this embodiment will be described. In the above DCC, MD, DAT, CD,
In both cases, the high-frequency limit is set to about 20 kHz, and the sampling frequency fs of the audio signal is corresponding to, for example, 4
It is about 4 kHz.

On the other hand, in the embodiment, a high sound quality mode is set in which the sampling frequency fs is set higher than 48 kHz in order to increase the high frequency reproduction limit. By increasing the sampling frequency fs, it is possible to further increase the high frequency reproduction limit, and it becomes possible to record and reproduce a high frequency sound of 20 kHz or higher.

In MPEG Audio, the sampling frequencies fs are 32 kHz, 44.1 kHz, 4
Only three types of 8.0 kHz are set. Therefore, if the sampling frequency fs is set to a value different from those standard values, it cannot be said that the format is strictly MPEG. However, the bit stream format shown in FIG. 3 and the encoding / decoding methods shown in FIGS. 4 and 5 can be commonly used even at such a high sampling frequency, so that they are quasi-compatible as a whole. Can be considered to be.

<Specific Numerical Example> Next, the disk of the above-mentioned embodiment will be described more specifically. First, the recording time (data transmission rate) is calculated. The recording capacity of the disc is 120 mm in diameter (area: 8605 m).
Considering the CD-DA of m ² ), it is about 783.2 Mbytes. In this embodiment, the diameter is 70
mm, the area is 1457 mm ² ), and the recording capacity of the disk of this embodiment is calculated from the area ratio to be 783.2 × (1457/8605) = 132.6 Mbytes (1).

Further, in this embodiment, as described above, C
The data format is D-ROM mode2 form1, and the user data in one sector of 2,352 bytes is 2,048 bytes. Therefore, the user data of the entire disc is 132.6 × (2048/2352) = 115.5 Mbytes = 115.5 × 10 ⁶ × 8 bits (2).

Here, the data transmission rate in the standard mode is 96 kbps for each of the L and R channels.
Therefore, 96 × 2 = 192 kbps = 192 × 10 ³ bps
, The recording time is 115.5 × 10 ⁶ × 8 bits / (192 × 10 ³ ) / 60
≒ 80 minutes …… (3)

The sampling frequency fs = 44.1
MPEG format when kHz = 44.1 × 10 ³ Hz, the number of bytes per frame is 1152 because the number of samples is 192 × 10 ³ /(44.1×10 ³ × 1152) / 8 bits ≈627 bytes …… (4)

This byte number of data will be stored in the user data area of the sector. In this case, it is convenient to set the relationship between the sector and the frame to be complete within a certain length. For example, 13 in 4 sectors
Considering the relationship of storing data for frames,
The user data of one sector is 2,04 as shown in FIG.
Since it is 8 bytes, one frame is 2048 × 4/13 ≒ 630 bytes ………………
………… It becomes (5).

When such a complete form is used, 1
Since sector = 1/75 sec, 4/75 ≈
Data can be accessed every 0.053 sec = 53 msec, which is convenient in terms of program cueing.

Next, the high sound quality mode will be described. Standard sound quality mode, data transmission rate 192kbps,
The sampling frequency fs is 44.1 kHz, and about 2.2 bits per sample. On the other hand, in the high-quality sound mode, for example, the data transmission rate, which is double the amount of data per hour, is 384 kbps, the sampling frequency fs is 64.0 kHz, and 3.0 bits per sample. In this case, the recording time is halved.

In this embodiment, since the size and format of the disc are changed, the disc data writing method may be any type such as a phase change disc, an optical disc, a magneto-optical disc, or the like. If the recording density of the disc is set to be several times higher than that of the current CD using the variable disc, it is possible to extend the data recording time, increase the data transmission rate, and improve the sound quality.

<Effects of Embodiment> As described above, according to this embodiment, the following effects are obtained. (1) Since the disc size is the same as the standard of the current CD except the outer diameter and the physical format is the same as the CD-ROM, the CD-DA, the CD-ROM, the video C
There is a high possibility that the recording device and the reproducing device will be commonly used by D and the like. (2) Physical format CD-ROM mode2 form1 E
Since the third error correction is performed using DC and ECC, it is possible to reduce the sound quality deterioration due to the uncorrectable error.

(3) Since the data format conforms to the MPEG international standard, it is also suitable for data transmission and recording via a communication line. (4) Sampling frequency fs = 64 as high sound quality mode
Since it has a high sound quality mode such as kHz, the high-frequency reproduction limit of the audio signal is high, and higher sound quality can be obtained as compared with systems such as CD and DAT.

<Other Embodiments> The present invention can be variously modified based on the above disclosure, and includes, for example, the following. (1) In the above embodiment, the outer diameter of the disk is set to 70 mm, but since the degree of freedom of the value of the outer diameter of the disk is high as described above, it may be appropriately set in consideration of data capacity, handling (usability) and the like. . (2) In the above-described embodiment, the recording time of the disc is set so that the high-quality sound mode is ½ of the standard mode, but it may be changed if necessary. If the high sound quality mode is set to an integer ratio (particularly about 1/2) with respect to the standard mode, it is very convenient in terms of design and use by the user.

[0043]

As described above, the present invention has the following effects. (1) The disk size is the same as the CD except for the outer diameter, and the physical format is CD-ROM mode2 form1.
Since it is adopted, good compatibility with the CD system can be ensured. (2) Since the third correction in addition to C1 and C2 by CIRC is performed by using EDC and ECC of CD-ROM mode2 form1, deterioration of sound quality due to uncorrectable error accompanying high efficiency encoding is avoided. be able to.

(3) Since the data format conforms to MPEG Audio, data transmission via the communication line can be favorably performed. (4) Since a mode with a high sampling frequency is provided, it is possible to obtain a good high frequency reproduction limit of voice.

[Brief description of drawings]

FIG. 1 is a diagram showing a disk size according to an embodiment of the present invention.

FIG. 2 is a diagram showing the sizes of a disk of the embodiment and a disk of another system in comparison.

FIG. 3 is a diagram showing a physical format of an embodiment.

FIG. 4 is a block diagram showing a configuration of an encoder of a disc according to an embodiment.

FIG. 5 is a block diagram showing a configuration of a decoder of the disc according to the embodiment.

FIG. 6 is a block diagram showing an additional circuit in the case of Layer3.

[Explanation of symbols]

 10 ... CD 12 ... CD single 14 ... MD jacket 16 ... Example disk 30 ... Band division filter 32 ... Normalization unit 31 ... MDCT unit 34 ... Quantization unit 36 ... Auditory psychological analysis unit 38 ... Adaptive bit allocation unit 40 ... Multiplexer 42 ... Demultiplexer 44 ... Inverse quantization section 46 ... Inverse normalization section 47 ... IMDCT section 48 ... Band synthesis filter DH ... Disk center hole WI ... Lead-in area WO ... Lead-out area WP ... Program area

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Claims (3)

[Claims] 1. The CD-ROM mode2 form1 is complied with, and EDC and ECC in the format are CIR of CIRC.
A physical format used for the third correction in addition to C2; a data format conforming to MPEG Audio in the standard mode; a data having a sampling frequency exceeding 48 kHz according to MPEG Audio in the high sound quality mode A data recording method that records data in the format. 2. A disk medium having the same physical size as a current CD except for the outer diameter and having data recorded by the method according to claim 1. 3. The disk medium according to claim 2, wherein data is written by utilizing a phase change.