JPH08235770A - Disk reproduction method and device - Google Patents

Abstract

PURPOSE: To simplify motor control, to facilitate and ensure random access and to eliminate acquisition loss of data by recording the data coded at a required variable coding rate in a definite linear density and reproducing the record at a definite angular velocity which satisfies a specified condition. CONSTITUTION: Coding processing is performed at a coding rate(bit/s) which varies between the maximums and minimum coding rates, CRmax and CRmin , both specified by the standard, and CLV recording on a disk 1 whose outermost peripheral and innermost peripheral radiuses are rmax and rmin (m) respectively is conducted at a definite linear recording density LRD(bit/S). In the region of this disk 1 where the radius is rmin , data is reproduced by the CAV system by selecting the angular velocity Wcav(rad/s) that satisfies the conditions exceeding that of equation II when the maximum reproduction transmitting rate TRmax (bit/s) satisfies the condition of equation I. Through this, control of the disk driving motor is simplified to facilitate and ensure random access and to eliminate the acquisition loss of data even in the inner peripheral region.

Description

Detailed Description of the Invention

[0001]

[Field of Industrial Application] A variable coding rate signal recorded at a constant linear recording density is recorded on a high density recording disk by CAV.
The present invention relates to a device for controlling and reproducing a signal.

[0002]

2. Description of the Related Art As an example of a method for reproducing a signal on a disc recorded at a constant linear recording density, Japanese Patent Laid-Open No. 59-1 is available.
85071.

[0003]

The above-mentioned conventional method uses C
Since reproduction is performed by LV control, abrupt change in disk rotation speed is required in trick play and the like, and it is difficult to control the motor and the like, and there is a problem that the access speed decreases. Needless to say, this causes further difficulty in reproducing a high-density recording disk.

[0004]

According to the present invention, a variable transmission rate signal recorded on a disk with a constant linear recording density is provided.
Signal reproduction is performed by controlling with CAV. At this time, the maximum transmission rate is ensured at the innermost circumference of the disk, and the disk rotation speed is adopted so that there is no data drop, and the CAV is used.
Perform control.

[0005]

When the data is read at different radial distances on the disk, the disk rotation speed remains constant, and even at the innermost circumference, the variable transmission rate signal is transmitted at the maximum transmission rate or higher. Data is reliably read out in a variable transmission rate system because a disk rotation speed that ensures speed is adopted.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is an example of the present invention and shows a graph of (a) recording medium disk 1 and (b) transmission rate versus angular velocity. In FIG. 1A, the data groups of the same amount recorded on the disc 1 recorded at a constant linear recording density occupy positions such as the recording area A2 at the innermost circumference and the recording area B3 at the outermost circumference. Constant linear velocity (C
If the data is reproduced by LV), the same amount of data can be read at any position on the disc within a unit time, but the rotational speed of the disc changes accordingly, which is disadvantageous for skip reading and the like. On the other hand, constant angular velocity (CA
Playback in V) reduces the load on motor control and is advantageous for random access. However, the radial position r [m]
The amount of data that can be read in a unit time varies depending on (the maximum value is rmax5 [m] on the outermost circumference and the minimum value is rmin4 [m] on the innermost circumference).

FIG. 2 shows an example of the coding rate of the variable transmission rate system. For example, a digital video disk or the like in which the coding rate CR is made variable according to the increase or decrease of the information amount of the image data. Here is an example. here,
The coding rate is the maximum value C defined by the standard.
From Rmax [bit / s] to the minimum value CRmin [bit
/ S], and the average is CRmean [bit /
s]. In the case of a signal according to the variable transmission rate system as shown in FIG. 2A, the amount of data that must be read within a unit time changes from moment to moment, so random access is essential even in normal reproduction.

FIG. 1B is a graph showing the transmission rate TR [bit / s] during the CAV control with respect to the angular velocity ω [rad / s]. The relationship 6 for the outermost circumference and the relationship 6 for the innermost circumference are shown. 2 of 7 are shown. The transmission rate TR [bit / s], which is the rate required for reading from the disc, is the coding rate CR [bit /
[s], plus a synchronization signal, an error correction code, and the like. Therefore, the maximum transmission rate TRmax8 [bit /
s] (TRmax ≧ CRmax), minimum transmission rate TR
min10 [bit / s] (TRmin ≧ CRmi
n), the average TRmean9 [bit / s] is the rate required for reading from the disc.

Therefore, the maximum transmission rate T in the innermost circumference
Angular velocity ωcav so that the signal can be read at Rmax8
[Rad / s] is adopted as the constant angular velocity in CAV control to reproduce the signal.

The transmission rate TR [bit / s] at the time of reading the data on the disk having the constant linear recording density by the reproduction processing of the CAV control is the radial position r [m] and the angular velocity ω.
[Rad / s] and linear recording density LRD [bit / m] are given by the equation TR = r * ω * LRD in FIG. Therefore, the lowest rate is the radial position r
When [m] is the minimum value rmin4, and also at that time, it is necessary to be able to send out the reproduction signal of the maximum rate TRmax8 given by the standard. From these, the angular velocity ωcav [rad / s] in CAV
Is determined by the equation of ωcav ≧ TRmax / (rmin * LRD).

Thus, in CAV control, even in the innermost circumference where the amount of data read out per unit time is the smallest,
The variable rate signal can be read through only the necessary data group within a predetermined time, and because of CAV control, the access speed does not drop due to time being taken by the motor control during random access.

Next, another example of the present invention is shown in FIG. Even for a disk recorded with a constant linear recording density, the actual linear recording density is within a certain fluctuation range, and is not a strictly constant linear recording density. The example of FIG. 3 is an example of the present invention in which the actual deviation of the linear recording density is taken into consideration.

The horizontal axis represents the angular velocity ω [rad /
s], the vertical axis indicates the read transmission rate TR during CAV control
[Bit / s] is shown. It is assumed that the transmission rate TR for a constant angular velocity fluctuates between the characteristic curve 11 and the characteristic curve 13 at the outermost circumference and between the characteristic curve 14 and the characteristic curve 16 at the innermost circumference due to the fluctuation of the linear recording density.

Since the transmission rate TR must always be equal to or higher than the maximum rate TRmax [bit / s] defined in the standard, the linear recording density is from (LRD-α) [bit / m] to (LRD + β) [bit / s]. m] range (α> 0, β>
0), the linear recording density is (LRD-
It is necessary to consider the case when it has fallen to α). Therefore, the lowest transmission rate is due to the equation TR = rmin * ω in FIG. 4B in which the linear recording density drops in the innermost circumference.
* (LRD-α), and finally CA
The angular velocity ωcav [rad / s] in the V control is set to ωc
It is determined so as to satisfy av ≧ CRmax / {rmin * (LRD-α)}.

In this way, even if the linear recording density varies, the variable rate signal can be reproduced by the CAV control reproducing process, which is advantageous for random access.

FIG. 4 shows an example of a disc reproducing apparatus for performing both CAV control of reproduction of a digital video disc and reproduction of a second type disc on which data other than images is recorded, and a constant linear recording density LRD. A recording disc 17 recorded at [bit / m], a pickup 18 for reading a signal from the disc 17 and outputting a reproduction signal 19, and a waveform equalization circuit 2 for inputting the reproduction signal 19 to perform waveform equalization processing.
0, a clock generation circuit 22 for generating a timing clock from the reproduction signal 19, a timing signal 23 output from the clock generation circuit 22, and an output signal 21 from the waveform equalization circuit 20 are input to input image data 30 and audio. The digital video disc reproduction signal processing circuit 24 for outputting the data 33, and further, the reproduction signal processing circuit 24 receives the output signal 21, performs error correction processing, etc., and sends the variable rate signal 26 to the buffer RAM 27. According to the variable rate from the processing circuit 25 and the buffer RAM 27,
An image decompression circuit 29 that reads out the compressed image data 28, decompresses it, and outputs decoded image data 30. Buffer R
There is an image decompression circuit 32 that reads out the compressed audio data 31 from the AM 27, decompresses it, and outputs the decoded audio data 33, and then inputs the timing signal 23 and the output signal 21 to input the second type disc. The second type data reproduction processing circuit 34, which decodes the data stored in and outputs the decoded data 35, the maximum rate designation signal 3
6, and a CAV control circuit 37 for CAV controlling the rotation of the disk.

The basic operation is as described above. At this time, the maximum transmission rate designating signal 36 is set so as to indicate the maximum transmission rate TRmax [bit / s] that the variable rate of the digital video disk can take. In accordance with the rate designation signal 36, the CAV control circuit 37 outputs the rate designation signal 3 at the innermost circumference of the disc (radius distance r [m] is rmin).
6 so that the signal can be read at the transmission rate TRmax [bit / s] shown in FIG.
Constant angular velocity ωcav satisfying / (rmin * LRD)
The disk is controlled to rotate at [rad / s].
Further, even when the second type disc containing the image data other than the image data is applied as the recording disc 17, the CAV control circuit 37 causes the disc to CAV by the constant angular velocity ωcav determined for the digital video disc by the above method. Control. That is, regardless of whether the recording disc 17 is a digital video disc or a second type disc in which data other than images is recorded, the same constant angular velocity ω
CAV reproduction processing is performed by cav.

In this way, both the digital video disc adopting the variable rate recording and the second type disc in which the data other than the image is recorded are reproduced without changing the angular velocity ωcav, so that there are two rotation control systems. There is no need to provide it. Therefore, the disk rotation control system process is simplified.

[0019]

Since the variable coding rate signal recorded on the high density disc is read out by the CAV control,
Control of the motor is simplified. Further, even when searching for another location on the disc such as trick play and starting the reproduction, it is not necessary to change the rotation speed of the motor, so that the time lag until a stable reproduction signal is obtained is reduced. Further, since the reproduction transmission rate at the innermost circumference is set to be equal to or higher than the maximum signal transmission rate, data drop is eliminated in the variable coding rate system.

[Brief description of drawings]

FIG. 1 is an example of angular velocity determination in a CAV control disc reproduction process to which the present invention is applied.

FIG. 2 shows an example of a coding rate fluctuation in a variable transfer rate system to which the present invention is applied and an example of calculation of an angular velocity in CAV control.

FIG. 3 shows an example in which the present invention is applied to a case where the linear recording density on a disc varies, and an example of calculation of an angular velocity in CAV control.

FIG. 4 shows an example in which the CAV control reproduction process of the present invention is performed commonly to both a digital video disc and a disc containing data other than images.

[Explanation of symbols]

1 ... High-density disc, 2 ... Innermost recording area A, 3 ... Outermost recording area B, 8 ... Maximum transmission rate, 9 ... Average transmission rate, 10 ... Minimum transmission rate, 17 ... High-density digital video disc, 18 …
Pickup, 24 ... Digital video disc reproduction signal processing circuit, 34 ... Second type data reproduction processing circuit,
37 ... CAV control circuit

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Masafumi Nakamura Inventor Masafumi Nakamura 292 Yoshida-cho, Totsuka-ku, Yokohama-shi Kanagawa Stock company Hitachi multimedia system development headquarters (72) Inventor Toshifumi Takeuchi Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa 292 Hitachi Co., Ltd. Multimedia system development headquarters

Claims (14)

[Claims] 1. At the time of recording, from a maximum value CRmax [bit / s] to a minimum value CRmin [bi according to a predetermined standard.
The coding process is performed at a coding rate that can vary between t / s] and a constant linear recording density LRD on the disc.
In the disc reproducing method of reproducing a signal recorded at [bit / m], the innermost radius of the signal recording area of the disc is rmin.
[M], the maximum playback transmission rate is TRmax [bit /
s] (TRmax ≧ CRmax), the angular velocity ωcav [rad / s] of the disc is TRmax / (rmin
* LRD) or more, the disc CAV reproducing method is characterized in that the reproducing process is performed by rotating at each constant speed. 2. At the time of recording, from the maximum value CRmax [bit / s] to the minimum value CRmin [bi according to a predetermined standard.
The coding process is performed at a coding rate that can vary between t / s] and a constant linear recording density LRD on the disc.
A disc reproducing method for reproducing a signal recorded at [bit / m], in which a radial position on the disc where a variable rate encoded signal starts is rvar [m], and a maximum reproducing transmission rate is TRmax.
When [bit / s] (TRmax ≧ CRmax), the angular velocity ωcav [rad / s] of the disc is TRmax /
A disk CAV characterized by performing playback processing by rotating at constant speeds of (rvar * LRD) or more.
How to play. 3. At the time of recording, from the maximum value CRmax [bit / s] to the minimum value CRmin [bi according to a predetermined standard.
A digital video disc for compressing and encoding image data at an encoding rate that can vary between t / s] and reproducing a signal recorded at a constant linear recording density LRD [bit / m] on the disc. Depending on the playback method, the innermost radius of the signal recording area of the disc is rmin
[M], the maximum playback transmission rate is TRmax [bit /
s] (TRmax ≧ CRmax), the angular velocity ωcav [rad / s] of the disc is TRmax / (rmin
* LRD) or more, the disc CAV reproducing method is characterized in that the reproducing process is performed by rotating at each constant speed. 4. A maximum value CRmax [bit / s] to a minimum value CRmin [bi according to a predetermined standard at the time of recording.
Disc reproducing method in which image data is compression-encoded at an encoding rate that can vary between t / s] and a signal recorded at a constant linear recording density LRD [bit / m] is reproduced on the disc. Then, the radial position on the disc where the variable rate encoded signal starts is rvar [m], and the maximum reproduction transmission rate is TRmax.
When [bit / s] (TRmax ≧ CRmax), the angular velocity ωcav [rad / s] of the disc is TRmax /
A disk CAV characterized by performing playback processing by rotating at constant speeds of (rvar * LRD) or more.
How to play. 5. At the time of recording, from the maximum value CRmax [bit / s] to the minimum value CRmin [bi according to a predetermined standard.
The coding process is performed at a coding rate that can vary between t / s] and a constant linear recording density LRD on the disc.
In the disc reproducing method of reproducing a signal recorded at [bit / m], the innermost radius of the signal recording area of the disc is rmin.
[M], the variation of the linear recording density of the disc is (LRD-
From α) [bit / m] to (LRD + β) [bit / m]
Range (where α> 0, β> 0), the maximum playback transmission rate is TRmax [bit / s] (TRmax ≧ CRmax)
, The angular velocity ωcav [rad / s] of the disc is T
Rmax / {rmin * (LRD-α)} or more,
A disk CAV reproducing method, characterized in that the reproducing process is performed by rotating at a constant speed. 6. A maximum value CRmax [bit / s] to a minimum value CRmin [bi according to a predetermined standard at the time of recording.
The coding process is performed at a coding rate that can vary between t / s] and a constant linear recording density LRD on the disc.
In a disc reproducing method for reproducing a signal recorded at [bit / m], the radial position on the disc where the variable rate coded signal starts is rvar [m], and the variation in the linear recording density of the disc is (LRD-α ) From [bit / m] (LRD + β)
[Bit / m] range (where α> 0, β> 0), the maximum reproduction transmission rate is TRmax [bit / s] (TRmax
≧ CRmax), the angular velocity of the disc ωcav [r
ad / s] is TRmax / {rvar * (LRD-
[alpha])} or higher, and a reproducing process is performed by rotating the disk at constant speeds to perform a reproducing process. 7. At the time of recording, from the maximum value CRmax [bit / s] to the minimum value CRmin [bi according to a predetermined standard.
A digital video disc for compressing and encoding image data at an encoding rate that can vary between t / s] and reproducing a signal recorded at a constant linear recording density LRD [bit / m] on the disc. In the playback device, the innermost radius of the disc is rmin [m], and the maximum playback transmission rate is TRmax [bit / s] (TRmax ≧ CR
max), the angular velocity ωcav [rad /
The disc CAV reproducing device is provided with a disc rotation number constant control means for controlling [s] to be a constant value of TRmax / (rmin * LRD) or more. 8. At the time of recording, from the maximum value CRmax [bit / s] to the minimum value CRmin [bi according to a predetermined standard.
A digital video disc for compressing and encoding image data at an encoding rate that can vary between t / s] and reproducing a signal recorded at a constant linear recording density LRD [bit / m] on the disc. In the playback device, the radial position on the disc where the variable rate coded signal starts is rvar [m], and the maximum playback transmission rate is TRmax.
When [bit / s] (TRmax ≧ CRmax), the angular velocity ωcav [rad / s] of the disc is set to TRmax /
A disc CAV reproducing apparatus comprising a disc rotation speed constant control means for controlling the speed to be a constant value not less than (rvar * LRD). 9. At the time of recording, from the maximum value CRmax [bit / s] to the minimum value CRmin [bi according to a predetermined standard.
The coding process is performed at a coding rate that can vary between t / s] and a constant linear recording density LRD on the disc.
In a disc reproducing device for reproducing a signal recorded at [bit / m], the innermost radius of the disc is rmin [m], and the variation of the linear recording density of the disc is (LRD-α) [bit / m] ( LRD + β) [bit / m] range (where α> 0,
β> 0), the maximum reproduction transmission rate is TRmax [bit /
s] (TRmax ≧ CRmax), the angular velocity ωcav [rad / s] of the disc is set to TRmax / {rmin
* (LRD-α)} A disc CAV reproducing device, which is provided with a disc rotation number constant control means for controlling to a constant value equal to or more than * (LRD-α)}. 10. At the time of recording, from the maximum value CRmax [bit / s] to the minimum value CRmin [b according to a predetermined standard.
The coding process is performed at a coding rate that can vary between [it / s] and a constant linear recording density LRD on the disc.
In a disc reproducing apparatus for reproducing a signal recorded at [bit / m], the radial position on the disc where the variable rate encoded signal starts is rvar [m], and the variation of the linear recording density of the disc is (LRD-α). ) From [bit / m] (LRD + β)
[Bit / m] range (where α> 0, β> 0), the maximum reproduction transmission rate is TRmax [bit / s] (TRmax
≧ CRmax), the angular velocity of the disc ωcav [r
ad / s] to TRmax / {rvar * (LRD-
[alpha])} A high-density disc CAV reproducing device, which is provided with a disc rotation speed constant control means for controlling the constant value to be a value equal to or above. 11. A claim 1, a claim 2, or a claim 3.
Alternatively, in the disc CAV reproducing method according to claim 4 or claim 5 or claim 6, especially TRmax> CRmax
CAV controlled disc angular velocity ωcav [rad / s] according to the maximum transmission rate TRmax [bit / s]
Disc CAV reproducing method, characterized in that 12. Claim 7 or claim 8 or claim 9.
Alternatively, in the disc CAV reproducing apparatus according to claim 10, particularly, the maximum transmission rate TRma where TRmax> CRmax.
A disc CAV reproducing device comprising a CAV control means for determining a disc angular velocity ωcav [rad / s] of CAV control in accordance with x [bit / s]. 13. The method according to claim 1, claim 2, or claim 3.
Alternatively, in the disc CAV reproducing method according to claim 4, 5, or 6, particularly when reproducing a disc on which image data is recorded or a disc on which data other than image is recorded, A disc CAV reproducing method characterized in that the disc is rotated at the same constant rotational speed to perform a reproducing process. 14. The method according to claim 7, claim 8 or claim 9.
Alternatively, in the disc CAV reproducing apparatus according to claim 10, the disc is rotated at the same constant rotation speed, particularly when reproducing a disc on which image data is recorded or a disc on which data other than image is recorded. A disc CAV reproducing apparatus comprising a disc rotation speed constant control means.