JPH10334596A - Disk device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a disk device capable of simultaneously recording bits of digital continuous information such as digital moving pictures in plural systems by one set of the disk device without deteriorating their quality. SOLUTION: This device has buffer memories 14 and 24 and a controller 36 for controlling the recording in two recording areas in different radial positions on an optical disk 34 in a time-division alternate manner. Digital moving picture data of two systems to be inputted are written alternately by a bit rate of the moving picture data in the buffer memories, and the moving picture data stored in the buffer memories are read out at a speed more than double of an average bit rate and are recorded on the optical disk by an optical head 33.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a disk device for recording and reproducing digital continuous data, particularly digital moving image data, and more particularly to a function of alternately recording and reproducing digital moving images of a plurality of systems in a time-division manner. The present invention relates to a disk device having:

[0002]

2. Description of the Related Art A video disk apparatus for recording and reproducing a digital moving image on a storage medium such as an optical disk using a digital moving image compression technique represented by MPEG has been developed.

According to a video disk apparatus using a conventional optical disk, a digital moving image compressor MPEG
Digital moving image data compressed by an encoder or digital moving image data distributed by broadcasting or CATV (cable television) is temporarily stored in a buffer memory at a predetermined bit rate. This buffer memory is used to adjust the difference between the bit rate of input digital moving image data (bit capacity transmitted per second) and the recording / reproducing speed of the optical disk (bit capacity capable of recording / reproducing per second). . Usually, the bit rate of the input digital moving image data is lower than the recording / reproducing speed of the optical disk.

When recording digital moving image data on an optical disk, the digital moving image data is read from the buffer memory at the recording speed of the optical disk, and then modulated by a modem to a signal suitable for recording, and transmitted to an optical head. The moving image data is input and digital moving image data is recorded on the optical disk by the optical head.

When reproducing digital moving image data from an optical disk, the optical head is moved to a radial position of the optical disk on which digital moving image data of a desired moving image is recorded, and the digital moving image data is transferred from the optical disk by the optical head. Read. The read digital video data is subjected to a demodulation process reverse to that at the time of recording, and is then input to a buffer memory. From the buffer memory, the digital video data is transmitted to an MPEG decoder which is a digital video decompressor at the bit rate of the digital video data. Sent and decompressed. The expanded moving image data is input to a monitor and displayed as a moving image.

[0006]

As one form of use of such a video disk device, there is a demand for recording a plurality of moving images in the same time zone due to an increase in the number of channels to be distributed. However, in the conventional video disk device as described above, only one system of digital moving images can be recorded at a time. Therefore, if a plurality of systems of digital moving images are to be simultaneously recorded, a plurality of video disk devices must be prepared. In addition, the cost burden on the user is large, and there is a problem of securing an installation space.

On the other hand, in an analog video recording and reproducing apparatus,
A system that can record two moving images simultaneously has been commercialized. However, in such a conventional analog video recording / reproducing device, it is necessary to narrow the recording band of one moving image, and thus the image quality is deteriorated.

As described above, according to the conventional technique, when a plurality of moving images are recorded in the same time zone by a video disk device, a plurality of video disk devices must be prepared, which imposes a cost burden on the user. However, there is a problem that the installation space is increased and the analog video recording / reproducing apparatus can simultaneously record two types of moving images. There was a problem that it deteriorated.

[0009] As another usage of the video disk device as described above, for example, when playing a game in which a plurality of viewpoints are displayed at the same time, or when confirming an editing point in video editing in advance, at the same time. In some cases, a request to reproduce a plurality of moving images may occur. But,
In the conventional video disk device as described above, if one system of digital video is to be reproduced at a time, a plurality of video disk devices must be prepared, which increases the cost burden on the user and increases the installation space. The problem of securing the

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a disk drive capable of simultaneously recording digital continuous information such as digital moving pictures of a plurality of systems without deterioration in quality.

Another object of the present invention is to provide a video disk device capable of simultaneously reproducing one digital moving image of a plurality of systems.

[0012]

SUMMARY OF THE INVENTION The present invention utilizes a difference between the recording speed of a disk-shaped recording medium such as an optical disk and the bit rate of continuous data such as digital moving image data to be input to a plurality of systems. A disk device for alternately recording digital continuous data in a plurality of recording areas having different radial positions on a recording medium via a buffer memory in a time-division manner.

According to the present invention, there is provided a head unit for recording digital continuous data on a disk-shaped recording medium, a buffer memory for temporarily storing a plurality of input digital continuous data, and a plurality of recording media having different radial positions on the recording medium. And a control unit for performing control for recording a plurality of digital continuous data in a recording area in a time-division manner, wherein the control unit is configured to perform control when recording one digital continuous data and when the head unit is accessing between the recording areas. Writing another one of the input digital continuous data to the buffer memory, and writing the other one of the input digital continuous data to the buffer memory when the other one of the digital continuous data is being recorded and when the head unit is accessing between the recording areas. When writing and recording the other one of the digital continuous data, the buffer The digital continuous data stored in the memory is read out at a recording speed of at least twice the average bit rate of the input digital continuous data and recorded in a corresponding one of the recording areas. The digital continuous data stored in the storage area is read out at a recording speed at least twice the average bit rate of the input digital continuous data and the corresponding one of the recording areas is read.
Provided is a disk device that performs control for recording data at a time.

That is, the present invention relates to a video disk apparatus for recording and reproducing digital continuous data such as digital moving image data by a recording / reproducing head using a disk-shaped recording medium.
First and second buffer memories for temporarily storing digital continuous data, respectively, and first and second digital continuous data in first and second recording areas having different radial positions on a recording medium. A control unit for performing control for alternately performing recording in a time-division manner.

Here, the control unit performs the following control. (A) When recording the second digital continuous data, and when the recording / reproducing head accesses between the first recording area and the second recording area, the first digital continuous data is input to the first digital continuous data.
Write to the buffer memory of

(B) When recording the first digital continuous data, and when the recording / reproducing head accesses between the first recording area and the second recording area, the second digital continuous data is input to the second digital continuous data. Write to the buffer memory of

(C) When recording the first digital continuous data, the digital continuous data stored in the first buffer memory is recorded at a recording speed at least twice the average bit rate of the input first digital continuous data. Read and record in the first recording area.

(D) When recording the second continuous digital data, the continuous digital data stored in the second buffer memory is recorded at a recording speed at least twice the average bit rate of the input first continuous digital data. The data is read and recorded in the second recording area.

Also, the first and second recording areas
And when the recording of the second digital continuous data is alternately performed in a time-division manner, the average recording time per recording of the first digital continuous data is T1 seconds, and the average recording time per recording of the second digital continuous data. , The maximum access time of the recording medium (the seek time required for the recording / reproducing head to move from the innermost circumference to the outermost circumference of the recording medium is 1 sec.
The recording speed of the first digital continuous data is (T1 + T2 + 2S), where S is the time obtained by adding the rotation time, and A (bps) is the average bit rate of the input first and second digital continuous data. * A / T1 (bp
s) or more, and the recording speed of the second digital continuous data is set to (T1 + T2 + 2S) * A / T2 (bps) or more.

According to the video disk apparatus of the present invention configured as described above, it is possible to simultaneously record a plurality of systems of digital continuation at the same time without deteriorating the image quality.
The reason will be described below.

The average bit rate A (bps) of the digital continuous data is defined as the maximum access time of the disk-shaped recording medium (the time required for the recording medium to make one rotation while the recording / reproducing head moves from the innermost circumference to the outermost circumference). ) Is defined as S seconds. In order to simultaneously record the first and second digital continuous data in the first and second recording areas having different radial positions with one recording / reproducing head, the recording on the recording medium is performed in a time-division manner by two systems of digital recording. It must be performed at a rate that does not fall below the average bit rate of continuous data. That is, the first digital continuous data is recorded in the first recording area for a certain time, and the second digital continuous data is recorded in the second recording area for a certain time. In order to process continuous data at the average bit rate A (bps), the recording / reproducing speed of the recording medium needs to be at least 2 * A (bps) or more.

Further, since the number of recording / reproducing heads is one, and the first and second recording areas on the recording medium have different radial positions, the access time between the areas is switched when the first and second digital continuous data are switched. Occurs. For example, “recording of T1 seconds of first digital continuous data” → “access of S seconds from the first recording area to the second recording area” → “second time”
When the time-division procedure consisting of "recording T2 seconds of digital continuous data of the second" and "accessing S seconds from the second recording area to the first recording area" is repeated to simultaneously record two sets of digital continuous data In this case, two accesses between recording areas occur in this one-cycle time-sharing procedure.

Accordingly, at the time of recording the first digital continuous data, the first digital continuous data input for (T1 + T2 + 2S) seconds is recorded during T1 seconds, so that the recording speed of the recording medium is ( T1 + T2 + 2S)
* A / T1 (bps) or more. Similarly, at the time of recording the second digital continuous data, the recording speed is (T1 + T2 + 2
S) * A / T2 (bps) or more. Also, T1 = T
When 2, the recording speed of the recording medium is (2 + 2S / T1) *
A (bps) or more. Here, 2S / T1 * A (b
ps) is the increase in recording speed required for two accesses.

On the other hand, as for the required buffer memory capacity, the capacity of the first buffer memory is twice the access time (the reciprocating time of the recording / reproducing head between the first recording area and the second recording area). This is the sum of the average recording time T2 of the second continuous digital data and the average transfer speed of the continuous digital data, and requires (2S + T2) * A bits or more. Similarly, the capacity of the second buffer memory is twice as long as the access time (reciprocation time of the movement of the recording / reproducing head between the second recording area and the first recording area) and the average recording time T1 of the first digital continuous data. Is multiplied by the average transfer rate of continuous data, and requires (2S + T1) * A bits or more. Therefore, the required capacity of the buffer memory is (4S) in total of the first and second buffer memories.
+ T1 + T2) * A bits or more.

When recording the first digital continuous data after satisfying the conditions of the recording speed of the recording medium and the capacity of the buffer memory, the recording / reproducing head is moved from the first recording area to the second recording area. An access is made in S seconds, the second digital continuous data is recorded on average T2 seconds, and the input is made while the recording / reproducing head is being accessed in S seconds from the second recording area to the continuously recording radial position of the first recording area in S seconds. The first digital continuous data to be recorded is stored in the first buffer memory, and the first digital continuous data is read out from the first buffer memory and written to the first recording area during the next average T1 seconds.

Similarly, at the time of recording the second digital continuous data, the recording / reproducing head accesses the first recording area from the second recording area in S seconds, and the first digital continuous data is averaged for T1 seconds. The second digital continuous data to be recorded, which is input while the recording / reproducing head is accessed in S seconds from the first recording area to the subsequent recording radius position of the second recording area, is recorded in the second buffer memory. In the second buffer memory for the next average T2 seconds.
Is read and written in the second recording area.

By repeating such an operation, recording of the first digital continuous data in the first recording area and recording of the second digital continuous data in the second recording area are performed by one recording / reproducing head. At the same time.

In a conventional analog video recording / reproducing apparatus for simultaneously recording two systems of moving images, it is necessary to narrow the recording band of one moving image. By recording continuous data in separate recording areas on a recording medium, the recording band is not narrowed, so that the quality of continuous information is not degraded.

Further, when the seek is retried when the seek fails, the recording of the first digital continuous data in the first recording area and the recording of the second digital continuous data in the second recording area are performed in a time division manner. The average recording time per time of the first digital continuous data is T1 seconds, the average reproduction time per time of the second digital continuous data is T2 seconds, and the maximum access time to the recording medium (recording time). (Seek time required for the reproducing head to move from the innermost circumference to the outermost circumference of the recording medium plus the time required for the recording medium to make one revolution) is S seconds, and the average bit rate of the first and second digital continuous data Is A (bps), and the maximum number of retries in case of seek failure is N, the recording speed of the first digital continuous data is (T1 + T2 + 2 * S (N + 1))
* A / T1 (bps) or more, and the recording speed of the second digital continuous data is (T1 + T2 + 2 * S (N + 1))
* A / T2 (bps) or more, and the first and second
The total storage capacity of the buffer memory of (4 * S * (N +
1) + T1 + T2) * A bits or more.

Further, the display screen of the display device is divided so that an image of the first digital continuous data being recorded in the first recording area and an image of the second digital continuous data being recorded in the second recording area are divided. Are displayed at the same time, it is possible to simultaneously confirm two systems of digital continuous information.

The present invention utilizes a difference between the reproduction speed of a disk-shaped recording medium such as an optical disk and the speed of input digital moving image data to store a plurality of systems of digital moving image data on a recording medium via a buffer memory. Are reproduced alternately in a time-division manner from a plurality of reproduction areas having different radial positions.

That is, the present invention relates to a video disk apparatus for recording and reproducing digital moving image data by a recording / reproducing head using a disk-shaped recording medium in a first and second recording areas having different radial positions on the recording medium. , And first and second buffer memories for temporarily storing first and second digital moving image data reproduced respectively from the first and second digital moving image data, and reproduction of the first and second digital moving image data is alternately performed in a time-division manner. And a control unit for performing control for performing the control.

Here, the control unit performs the following control. (A) The first digital moving image data to be reproduced during the reproduction of the second digital moving image data and while the recording / reproducing head is accessing between the first recording area and the second recording area. 2 of average bit rate of digital video data
The data is reproduced in advance from the first recording area at a reproduction speed twice or more and written in the first buffer memory.

(B) The second digital moving image data to be reproduced during reproduction of the first digital moving image data and while the recording / reproducing head is accessing between the first recording area and the second recording area. The data is reproduced from the second recording area in advance at a reproduction speed twice or more the average bit rate of the second digital moving image data and written into the second buffer memory.

(C) When reproducing the first digital moving image data, the digital moving image data stored in the first buffer memory is read out at the bit rate of the first digital moving image data.

(D) When reproducing the second digital moving image data, the digital moving image data stored in the second buffer memory is read at the bit rate of the second digital moving image data.

Further, the average reproduction per time of the first digital moving image data when the reproduction of the first and second digital moving image data from the first and second recording areas is alternately performed in a time-division manner. The time is T1 second, the average reproduction time per second of the second digital moving image data is T2 seconds, and the maximum access time of the recording medium (required for the recording / reproducing head to move from the innermost circumference to the outermost circumference of the recording medium). When the seek time plus the time required for the recording medium to make one revolution) is S seconds, and the average bit rate of the first and second digital moving image data is A (bps), the first digital moving image data Reproduction speed is (T1 + T2 + 2S) * A / T1 (bp
s) or more, and the reproduction speed of the second digital video data is (T1 + T2 + 2S) * A / T2 (bps) or more.

In the video disk apparatus of the present invention configured as described above, a single unit can simultaneously reproduce a plurality of digital moving images. The reason will be described below.

The average bit rate A (bps) of the digital moving image data is taken as the maximum access time of the disk-shaped recording medium (the recording medium makes one rotation during the time when the recording / reproducing head moves from the innermost circumference to the outermost circumference of the recording medium). The time obtained by adding the time is S seconds. The first and second digital moving image data are transferred by a single recording / reproducing head to a first digital moving image data having different radial positions.
In order to simultaneously reproduce from the second recording area, it is necessary to perform reproduction from the recording medium in a time-division manner at a speed not lower than the average bit rate of the two systems of digital moving image data. That is, the first digital moving image data is reproduced from the first recording area for a certain time, and the second digital moving image data is reproduced from the second recording area for a certain time. In order to process the digital moving image data at the average bit rate A (bps), the reproduction speed of the recording medium is at least 2 * A (bps).
It is necessary to be above.

Further, since there is one recording / reproducing head and the first and second recording areas on the recording medium have different radial positions, access between the areas is required for switching between the first and second digital moving image data. Time arises. For example, "1st
Reproduction of digital moving image data of T1 seconds ”→“ Access of S seconds from first recording area to second recording area ”→
"Reproduction of the second digital moving image data for T2 seconds" →
When the time-division procedure consisting of "access from the second recording area to the first recording area for S seconds" is repeated to simultaneously reproduce two systems of digital moving image data, this one-cycle time-division procedure is used. , Two accesses between the recording areas occur.

Therefore, when the first digital moving image data is reproduced, the first digital moving image data for (T1 + T2 + 2S) seconds is reproduced from the recording medium during T1 seconds, so that the reproduction speed of the recording medium is increased. Is (T1 + T2 + 2
S) * A / T1 (bps) or more. Similarly, when reproducing the second digital moving image data, the reproduction speed is (T1 + T
2 + 2S) * A / T2 (bps) or more. Also, T
When 1 = T2, the reproduction speed of the recording medium is (2 + 2S / T
1) * A (bps) or more. Here, 2S / T1 *
A (bps) is an increment of the reproduction speed required for two accesses.

On the other hand, the required buffer memory capacity is as follows: the capacity of the first buffer memory is twice the access time (the reciprocating time of the recording / reproducing head between the first recording area and the second recording area); 2 is the sum of the average reproduction time T2 of the digital video data and the average transfer speed of the digital video data, and requires (2S + T2) * A bits or more. Similarly, the capacity of the second buffer memory is twice as long as the access time (the reciprocating time for moving the recording / reproducing head between the second recording area and the first recording area) and the average reproducing time of the first digital moving image data. The sum of T1 is multiplied by the average transfer speed of moving image data, and (2S + T1) *
A bit or more is required. Therefore, the capacity required for the buffer memory is equal to or more than (4S + T1 + T2) * A bits in total of the first and second buffer memories.

When the first digital moving image data is reproduced after satisfying the conditions of the reproducing speed of the recording medium and the buffer memory capacity, the recording and reproducing head is moved from the first recording area to the second recording area. Is accessed in S seconds, the second digital moving image data is reproduced on average T2 seconds, and the recording / reproducing head is accessed in S seconds from the second recording area to the continuously reproduced radial position of the first recording area. The first digital moving image data to be reproduced is reproduced for an average of T1 seconds and written into the first buffer memory.

Similarly, when reproducing the second digital moving image data, the recording / reproducing head accesses the second recording area to the first recording area in S seconds to average the first digital moving image data. The second digital moving picture data to be recorded for T1 seconds and to be reproduced while accessing the recording / reproducing head in S seconds from the first recording area to the subsequent recording radial position from the second recording area to the second buffer memory. And reproduces the data for the next average T2 seconds and writes the data to the second buffer memory.

While the reproduction is not performed from the recording medium, the first and second digital moving image data are read out from the first and second buffer memories at the bit rate of the digital moving image data, for example, by a digital moving image data expander. After decompression, output to the display device.

By repeating such an operation, reproduction of the first digital moving image data from the first recording area and reproduction of the second digital moving image data from the second recording area are performed by one recording operation. This can be performed simultaneously by the reproducing head.

When the seek operation is retried when the seek fails, the reproduction of the first digital moving image data from the first recording area and the reproduction of the second digital moving image data from the second recording area are performed. The average reproduction time per cycle of the first digital moving image data is T1 seconds, the average reproduction time per cycle of the second digital moving image data is T2 seconds, and the maximum recording time for the recording medium when alternately performed by time division. The access time (the seek time required for the recording / reproducing head to move from the innermost circumference to the outermost circumference of the recording medium plus the time required for the recording medium to make one rotation) is S seconds, and the first and second digital moving images Assuming that the average bit rate of data is A (bps) and the maximum number of retries in case of seek failure is N, the reproduction speed of the first digital video data is (T1 + T2 + 2
* S (N + 1)) * A / T1 (bps) or more,
(T1 + T2 +
2 * S (N + 1)) * A / T2 (bps) or more, and the sum of the storage capacities of the first and second buffer memories may be (4 * S * (N + 1) + T1 + T2) * A bits or more. .

Further, the display screen of the display device is divided into an image of the first digital moving image data being reproduced from the first recording area and a second digital moving image data being reproduced from the second recording area. Are displayed at the same time, it is possible to simultaneously confirm two systems of digital moving images.

[0049]

FIG. 1 shows the configuration of a disk device used for recording and reproducing digital continuous data, particularly a video disk device according to an embodiment of the present invention. This video disk device includes first and second analog image input sections 11 and 21 and a digital moving image data compressor MP.
EG encoders 12 and 22, digital image input unit 1
3, 23, first and second buffer memories 14, 2
4. MPEG decoders 15 and 25, which are digital video data decompressors for an image monitor, a switch 31, a modem 32, an optical head 33, an optical disk 34, a monitor 35 for displaying a reproduced image, and control of each unit And a controller 36 that performs the operation.

Hereinafter, the operation of this embodiment will be described.

In the following description, the bit rate of digital video data distributed from the MPEG encoders 12 and 22, CATV, satellite broadcasting, and the like is assumed to be 4 Mbps on average. The recording / reproducing speed (data transfer speed) of digital moving image data on the optical disk 34
Is 12 Mbps. Further, the optical disk 34 is shown in FIG.
, The first and second radial positions are different.
Recording areas 41 and 42. The capacity of each of the first and second buffer memories 14 and 24 is 6
M bits.

In the following operation, the recording operation on the optical disk 34 by the optical head 33, the buffer memory 1
The writing / reading operations of 4, 24 and the switching control of the switch 31 are all performed under the control of the controller 36.

First, the recording operation of one ordinary digital moving image data will be described.

When the input moving image data signal is an analog moving image signal such as an NTSC signal, the analog moving image signal is input from the analog image input section 11 or 21 and is digitally converted and image-converted by the MPEG encoder 12 or 22. Is input to the digital image input unit 13 or 23. On the other hand, already compressed digital video data delivered from CATV, satellite broadcasting, etc., is directly input to the digital image input unit 13 or 23.

Here, first, the digital image input unit 1
The case where the first digital moving image data is input from No. 3 will be described. The first digital moving image data input from the digital image input unit 13 is written to the first buffer memory 14 at a speed of, for example, 4 Mbps.
When an appropriate amount of digital moving image data is written to the buffer memory 14, the digital moving image data is read from the buffer memory 14 at 12 Mbps, which is the recording speed of the optical disk 34, and is input to the switch 31. Here, the switch 31 inputs the digital moving image data from the first buffer memory 14 to the modem 32 when recording the first digital moving image data, and outputs the second digital moving image data when recording the second digital moving image data. The digital video data from the second buffer memory 24 is switched by the controller 36 so as to be input to the modem 32.

The digital moving image data input to the modulator / demodulator 32 is modulated into a signal suitable for recording, and a known optical head 33 having a semiconductor laser, an objective lens, a photodetector and the like (not shown) as main components. Is recorded on an optical disk 34 by the optical head 33. The optical disk 34 is a recordable / reproducible medium, and specifically, is a phase change recording medium, a magneto-optical recording medium, or the like.

Since the recording speed of the optical disk 34 is higher than the bit rate of the digital moving image data, the buffer memory 14 may be emptied. In this case, the recording on the optical disk 34 is interrupted. The process is repeated from the operation of storing data. Accordingly, the input of the digital moving image data to the buffer memory 14 is performed continuously, but the recording of the digital moving image data on the optical disk 34 is performed by the controller 36.
, The digital moving image data is read out intermittently from the buffer memory 14 and is read out intermittently.

For example, when the digital moving image data stored in the buffer memory 14 accumulates 4 Mbits or more, recording on the optical disk 34 is performed. When 4 Mbits of digital moving image data is stored in the buffer memory 14, the digital moving image data from the digital image input unit 13 is read out at 4 Mbps while the digital moving image data is read out from the buffer memory 14 at a speed of 12 Mbps.
s, the buffer memory 14 stores 4 Mbits / (12 Mbps−4 Mbits).
(bps) = approximately 0.5 seconds, and the recording on the optical disc 34 is interrupted. Buffer memory 14 in next 1 second
Becomes 4M bits, and recording is performed on the optical disk 34 again. Next, the operation of recording the first and second digital moving image data simultaneously on the optical disk 34, which is a characteristic operation of the present invention, will be described. As described above, the optical disc 34 has a period in which the recording is interrupted during the recording of the first digital moving image data, and the recording of the second digital moving image data can be performed using this time.

The second digital moving image data input from the digital image input unit 23 is processed in the same manner and in parallel with the first digital moving image data. That is,
The second digital moving image data is recorded on the optical disk 34 via the second buffer memory 24, the switch 31, the modem 32, and the optical head 33.

Here, as shown in FIG. 2, a first recording area 41 for recording the first digital moving picture data and a second recording area 42 for recording the second digital moving picture data are formed on an optical disc. The radial positions on 34 are different.
Therefore, movement between the recording areas 41 and 42 of the optical head 33, that is, access is required. The first and second digital moving image data input during access between the recording areas 41 and 42 are stored in the buffer memories 14 and 24, respectively.

FIG. 3 is a flowchart showing a processing procedure for simultaneously recording the first and second digital moving image data in this embodiment. First, it is checked whether or not digital moving image data is stored in the first buffer memory 14 at 2 M bits or more (step S1). here,
If the digital moving image data is stored in the first buffer memory 14 at 2 M bits or more, the optical head 33 is moved to the first recording area 41 of the optical disk 34 (step S2). Until the buffer memory 14 becomes empty, the first digital moving image data is read from the buffer memory 14 and recorded in the first recording area 41 (steps S3 to S3).
4).

Next, the optical head 33 is moved to the second recording area 42 of the optical disk 34 (step S5), and the buffer memory 24 is emptied until the second buffer memory 24 becomes empty.
, The second digital moving image data is read out and recorded in the second recording area 42 (steps S6 to S7).

Thereafter, the flow returns to step S2 and the optical disk 3
4, the recording of the first digital moving image data in the first recording area 41 and the recording of the second digital moving image data in the second recording area 42 are alternately repeated.

FIGS. 4A and 4B show digital moving image data in the first and second buffer memories 14 and 24 when the first and second digital moving image data are simultaneously recorded in the present embodiment. It is a figure showing the time change of quantity.
In this example, the average of the access time between the first and second recording areas 41 and 42 is set to 0.25 seconds. It is also assumed that the optical head 33 is located in the first recording area 41. The operation at the time of simultaneous recording according to the present embodiment will be described in detail step by step with reference to FIG.

(1) Since recording is not performed for the first 0.5 seconds, the first and second buffer memories 14 and 2
4 stores digital moving image data of 4M bits * 0.5 seconds = 2M bits.

(2) During the next 0.25 seconds, the first digital moving image data stored in the first buffer memory 14 is read at a speed of 12 Mbps, and the optical disk 34
Is recorded in the first recording area 41. As a result, the first digital moving image data remaining in the first buffer memory 14 is 2 Mbits- (12 Mbps-4 Mbps) *
0.25 seconds = 0. At this time, since the second digital moving image data stored in the second buffer memory 24 is not recorded on the optical disk, the second digital moving image data in the buffer memory 24 is 2 Mbits + 4 Mbp.
s * 0.25 seconds = 3M bits.

(3) In the next 0.25 seconds, the optical head 3
3 is moved from the first recording area 41 to the second recording area 42 to perform access. During this access, the optical disk 3
4, since no recording is performed, the first buffer memory 1
4 is 4 Mbps *.
0.25 seconds = 1 Mbit, and the digital moving image data in the second buffer memory 24 is 3 Mbit + 4 Mb
ps * 0.25 seconds = 4 M bits.

(4) For the next 0.5 seconds, the second digital moving image data stored in the second buffer memory 24 is recorded on the optical disk 34 at a speed of 12 Mbps, and the second digital moving image data remaining in the buffer memory 24 is stored. The digital moving image data is 4 Mbits- (12 Mbps) * 0.5 seconds = 0. At this time, since the first digital moving image data stored in the first buffer memory 14 is not recorded on the optical disk, the first digital moving image data in the buffer memory 14 is 1 Mbit + 4 Mbps * 0.5 seconds = 3 M
Bit.

(5) For the next 0.25 seconds, the optical head 33
Is moved from the second recording area 42 to the first recording area 41 to perform access. During this access, the optical disk 34
No recording is performed in the first buffer memory 14.
Of the first digital moving image data is 3M bits + 4M
bps * 0.25 seconds = 4 Mbits, and the digital moving image data in the second buffer memory 24 is 4 Mbps.
* 0.25 seconds = 1 Mbit.

(6) During the next 0.5 second, the first digital moving image data stored in the first buffer memory 14 is recorded on the optical disk 34 at a speed of 12 Mbps, and the second digital moving image data remaining in the buffer memory 14 is stored. Is 4 Mbits- (12 Mbps-4 Mbps) * 0.
5 seconds = 0. At this time, the second buffer memory 24
Since the second digital moving image data stored in the buffer memory 24 is not recorded on the optical disk, the second digital moving image data in the buffer memory 24 is 1 Mbit + 4 Mbps *
0.5 seconds = 3 Mbits.

Thereafter, the access of the optical head 33 from the first recording area 41 to the second recording area 42 (0.25 seconds) →
(Recording of the second digital moving image data in the second recording area 42) → from the second recording area 42 to the first recording area 41
From the optical head 33 (0.25 seconds) to the recording of the first digital moving image data in the first recording area 41 (0.5 seconds) are repeated.

As can be seen from FIG. 4, both the first digital moving image data in the first buffer memory 14 and the second digital moving image data in the second buffer memory 24 exceed the buffer memory capacity. Indicates that the recording of the first and second digital moving image data on the optical disk 34 is performed alternately.

Next, the recording speed of the optical disk 34 required in the present invention will be described. The average bit rate of the first and second digital video data in the present embodiment is A
= 4 Mbps, and the maximum access time of the optical disk 34 (the time obtained by adding the time required for the optical head 33 to move from the innermost circumference to the outermost circumference plus the time required for the optical disk 34 to make one rotation) is S = 0. 25 seconds.

In order to simultaneously record the first and second digital moving image data on the first and second recording areas 41 and 42 of the optical disk 34 with one optical head 33, two systems of digital moving image It is necessary to record data alternately in a time-division manner and at a speed not lower than the average bit rate of the digital video data of the two systems. That is, the first digital moving image data is recorded for a certain period of time, and the second digital moving image data is recorded for a certain period of time, so that two systems of digital moving image data are processed at an average bit rate of 4 Mbps. Indicates that the recording speed of the optical disk 34 is at least 2 * 4 Mbps = 8 Mbps.
s or more is required.

Further, the number of the optical head 33 is one, and the first and second recording areas 41 and 4 on the optical disc 34 are provided.
Since the position of 2 is not always the same, an access time between the recording areas 41 and 42 occurs when the recording area is switched. For example, “recording of first digital moving image data in the first recording area 41” → “access from the first recording area 41 to the second recording area 42” → “access to the second recording area 42” When recording is performed by repeating the time-division procedure consisting of “recording of second digital moving image data” → “access from second recording area 42 to first recording area 41”, one time-division procedure Causes two accesses. Therefore, at the time of recording, digital moving image data input between this recording time and two accesses must be recorded within an average recording time of 0.5 seconds of the digital moving image data on the optical disk 34. .

As shown in FIG. 4B, the average recording time per recording of the first digital moving image data is 0.2 at the beginning only.
After 5 seconds, it becomes 0.5 seconds each, and that of the second digital moving image data is also 0.5 seconds. The average access time is 0.25 seconds. Therefore, the recording speed of the optical disk 34 is (0.5 + 0.5 + 2 * 0.25) * 4Mb
ps / 0.5 second = 12 Mbps or more. Here, 4 Mbps is an increase in the recording speed required for two accesses. The recording / reproducing speed of the optical disc 34 in the present embodiment is 12 Mbps, which satisfies this condition.

Next, the buffer memory capacity required in the present invention will be described. First, the capacity required for the first buffer memory 14 is twice the maximum access time S (the reciprocating time of the optical head 33 between the first recording area 41 and the second recording area 42) and the second digital moving image. The sum of the average recording time T2 of the image data and the average transfer speed of the digital moving image data is multiplied by (2S + T2) * A bits or more. In this case, (2 * 0.25 + 0.5) * 4
= 4M bits or more.

Similarly, the capacity required for the second buffer memory 24 is twice as long as the access time (the reciprocating time of the optical head 33 between the second recording area 42 and the first recording area 41) and the first time. The sum of the average recording time T1 of the digital moving image data and the average transfer speed of the digital moving image data is multiplied by (2S + T1) * A bits or more. In this case, (2 * 0.25 + 0.5) * 4 = 4M bits or more.

Therefore, the required buffer memory capacity is the first
And the sum of the second buffer memories 14 and 24 is 8 Mbits or more. In the present embodiment, both the first and second buffer memories 14 and 24 have 6 Mbits, which is 12 Mbits in total, so that this condition is satisfied.

However, it can be seen from FIG. 4 that the first and second buffer memories 14 and 24 use only a maximum of 4 Mbits, so that the capacity may be 4 Mbits. Therefore, the capacity of the buffer memories 14 and 24 can be set to 4 Mbits depending on the memory control.

After satisfying the conditions of the recording speed of the optical disc 34 and the buffer memory capacity, in the first digital moving image data recording system, light is transferred from the first recording area 41 to the second recording area 42. Access the head 33,
The second digital moving image data is recorded for an average of 0.5 seconds, and the first digital data to be recorded while the optical head 33 is being accessed from the second recording area 42 to the continuously recording radial position of the first recording area 41 is recorded. The digital moving image data is stored in the first buffer memory 14, and the first moving image data is stored in the first
The digital moving image data is read from the buffer memory 14 and written to the optical disk 34.

On the other hand, in the recording system of the second digital moving image data, the second recording area 42 to the first recording area 41
The optical head 33 is accessed to record the first digital moving image data for an average of 0.5 seconds, and the first recording area 41 is recorded.
The second digital moving image data to be recorded is stored in the second buffer memory 24 while the optical head 33 is being accessed at the radial position of the second recording area 42 where the subsequent recording is to be performed. The digital moving image data is read from the second buffer memory 24 and the optical disk 34 is read.
Write to.

By such an operation, the first and the second
Digital moving image data can be simultaneously recorded by the single optical head 33 in the first and second recording areas 41 and 42 at different radial positions on the optical disc 34.

FIG. 5 shows a display example on the monitor 35 in this embodiment. The display screen 50 of the monitor 35 is divided into two, and the recorded image 51 of the first digital moving image data is divided.
And the recorded image 52 of the second digital moving image data is divided and displayed simultaneously, so that the two recorded images 51,
52 can be monitored simultaneously.

In this monitor display, in this embodiment, the first and second digital moving image data read from the buffer memories 14 and 24 are combined with the MPEG decoder 15 and
25, the data is output to the monitor 35. However, if the input moving image signal is analog, M
PEG encoders 12 and 22, digital image input unit 1
3 and 23, and may be directly input to the monitor 35 without passing through the MPEG decoders 15 and 25.

Movement from one recording area to another recording area on the optical disk 34, that is, a seek operation may fail because the address information recorded on the optical disk 34 can be read. In such a case, the video disk device according to the present embodiment seeks again up to the retry count included in advance. Considering this retry at the time of seek failure, the bit rate of digital moving image data is set to A
(Bps), the maximum access time to the optical disc 34 (the time obtained by adding the time for the optical head 33 to seek from the innermost circumference to the outermost circumference of the optical disc 34 and the time for the optical disc 34 to make one revolution) is S seconds, When the maximum number of retries upon failure is N, the seek time is the maximum (N + 1) *
As S seconds, the recording speed of the optical disk 34 and the capacities of the buffer memories 14 and 24 may be estimated.

Therefore, the recording speed of the first digital moving image data is (T1 + T2 + 2 * S * (N + 1)) * A
/ T1 (bps) or more, the recording speed of the second digital moving image data is (T1 + T2 + 2 * S * (N + 1)) *
A / T2 (bps) or more, buffer memory 14, 24
Is equal to (4 * S * (N + 1) + T1 + T
2) If the bit length is * A bits or more, even if there is a retry in the seek of the optical head 33, the digital moving image data during the reseek can be stored in the buffer memories 14 and 24. Obviously, it can be recorded seamlessly.

In the above-described embodiment, the case of simultaneously recording two systems of digital moving image data has been described.
Next, the simultaneous recording of digital moving image data of three systems will be described.

In order to simultaneously record three digital moving pictures with one recording / reproducing head, three moving pictures are recorded on a disk at a speed not lower than the average bit rate of the three digital moving pictures in a time-division manner. There is a need. The moving image 1 is recorded on the disk for a certain time, the moving image 2 is recorded on the disk for a certain time, and the moving image 3 is recorded for a certain time. In order to process three moving images,
A recording / reproducing speed to the disc of 3 * Abit / s or more is required. Furthermore, since there is one recording / reproducing head and the position of each recording area on the disc is not always the same, an access time between the areas is required for switching between each recording. For example, “Recording of T1 second” → “Accessing S seconds from recording area 1 to recording area 2” → “Recording of T2 seconds” →
"Access for S seconds from recording area 2 to recording area 3" →
“T3 seconds recording” → “S from recording area 3 to recording area 1”
In the case where recording is performed by repetition of the time division procedure consisting of [second access], three accesses occur in one time division procedure.

Accordingly, at the time of the first recording, digital moving image data to be inputted for (T1 + T2 + T3 + 3 * S) seconds is recorded during T1 seconds, so that the recording speed of the first moving image is (T1 + T2 + T3 + 3 * S). T1 + T2 + T3 + 3 * S) * A
/ T1 (bps) or more. Similarly, the recording speed of the second moving image is (T1 + T2 + T3 + 3 * S) * A / T2 (b
ps) or more, and the recording speed of the third moving image is also T
1 + T2 + T3 + 3 * S) * A / T3 (bps) or more.

On the other hand, the required buffer memory capacity is three times the access time (the reciprocating time of the optical head moving in the recording area 1 and the recording area 2 and the recording area 3) and the other two moving images are recorded. The value obtained by multiplying the sum of the times by the average transmission speed of the moving image, and the buffer memory required for each moving image is (3 * S + T2 + T3) * Abit
As described above, the second moving image requires (3S + T1 + T3) * A bits or more, and the third moving image requires (3 * S + T1 + T2) * A bits or more. Therefore, in total, (9 * S + 2 * T1
+ 2 * T2 + 2 * T3) * Abit or more.

If these conditions of the recording / reproducing speed of the disc and the buffer capacity are satisfied, the access time of three times and each digital moving picture to be recorded during the recording of the other two moving pictures on the disc are stored in the buffer memory. It is memorized. The moving image data in the buffer memory is recorded on each disk when recording on each disk. Digital moving images delivered by repeating these steps are continuously recorded on the optical disk without any loss.

FIG. 6 is an example showing a time change of a digital moving image in the buffer memory corresponding to each moving image when three moving images are simultaneously recorded. There are three buffer memories corresponding to each moving image, the average bit rate of the moving image is A = 4M hit / s, and the maximum access time is S =
It is assumed that 0.2 seconds and T1 = T2 = T3 = 0.6 seconds.

The recording speed required to record three moving images simultaneously is (T1 + T2 + T3 + 3 * S) A / T1
= 16 Mbit / s or more. The required buffer memory is (3 * S + T1) per buffer memory.
+ T2) * A = 7.2 Mbit, and the sum of the three buffer memories 1, 2, 3 is 7.2 * 3 = 21.6 Mbit. These three buffers 1, 2, and 3 correspond to moving images 1, 2, and 3, respectively.

(0) For the first 0.6 seconds, the 7.2 Mbit moving image data 1 in the buffer 1 is 16 Mbit / s.
Since the moving image 1 is sent to the buffer 1 at 4 Mbit / s while recording on the disk, the buffer 1 has 7.2 Mbit.
-(16-4) * 0.6 = 0.

On the other hand, the buffer 2 in which the moving image data 2 of 4 Mbit is stored in the buffer 2 at 4 Mbit / s.
Is sent, so buffer 1 is 4Mbit + 4 *
0.6 = 6.4 Mbit.

On the other hand, the buffer 3 having the moving image data 3 of 0.8 Mbit only transmits the moving image 3 to the buffer 3 at 4 Mbit / s.
t + 4 * 0.6 = 3.2 Mbit.

(1) During the next first 0.2 seconds, a seek is performed from the recording area of the moving image 1 to the recording area of the moving image 2, so that the moving image is stored in each buffer and the capacity is 4 Mb.
it * 0.2 = increase by 0.8 Mbit. That is, buffer 1 has 0 + 0.8 = 0.8 Mbit, buffer 2 has 6.4 + 0.8 = 7.2 Mbit, and buffer 3
Is 3.2 + 0.8 = 4 Mbit.

(2) In the next 0.6 seconds, since the buffer 1 having the moving image data 1 of 0.8 Mbit only sends the moving image 1 to the buffer 1 at 4 Mbit / s, the buffer 1 has 0.8 Mbit + 4. * 0.6 = 3.2 Mbit. On the other hand, the 7.2 Mbit moving image data 2 in the buffer 2 is recorded on the disk at 16 Mbit / s while the 4M
Since the moving image 2 is transmitted to the buffer 2 at bit / s, the buffer 1 stores 7.2 Mbit− (16−4) * 0.6 =
It becomes 0.

On the other hand, the buffer 3 having the moving image data 3 of 4 Mbit is stored in the buffer 3 at 4 Mbit / s.
Is sent, buffer 3 is 4Mbit + 4 *
0.6 = 6.4 Mbit.

(3) In the next first 0.2 seconds, seeking from the recording area of the moving image 2 to the recording area of the moving image 3 is performed, so that the moving image is recorded in each buffer and the capacity is 4 Mbi.
t / s * 0.2 = 0.8 Mbit. That is, buffer 1 is 3.2 + 0.8 = 4 Mbit, buffer 2 is 0 + 0.8 = 0.8 Mbit, and buffer 3 is
6.4 + 0.8 = 7.2 Mbit.

(4) In the next 0.6 seconds, the buffer 1 having the moving image data 1 of 0.8 Mbit only sends the moving image 1 to the buffer 1 at 4 Mbit / s, so the buffer 1 has 4 Mbit + 4 * 0.6 = 6.4 Mbit. On the other hand, the buffer 2 having the moving image data 2 of 0.8 Mbit only transmits the moving image 2 to the buffer 2 at 4 Mbit / s, so the buffer 2 has 0.8 Mbit + 4 *
0.6 = 3.2 Mbit. On the other hand, the 7.2 Mbit moving image data 3 in the buffer 3 is 16 Mbit / s.
Since the moving image 3 is sent to the buffer 3 at 4 Mbit / s while recording on the disk, the buffer 3 has 7.2 Mbi.
t- (16-4) * 0.6 = 0.

(5) During the next first 0.2 seconds, a seek operation is performed from the recording area of the moving image 3 to the recording area of the moving image 1, so that the moving image is stored in each buffer, and the capacity is 4 Mb.
it / s * 0.2 = 0.8 Mbit. That is, the buffer 1 has 6.4 + 0.8 = 7.2 Mbit, the buffer 2 has 3.2 + 0.8 = 4 Mbit, and the buffer 3 has 0 + 0.8 = 0.8 Mbit.

(6) For the first 0.6 seconds, the moving image data 1 of 7.2 Mbit in the buffer 1 is 16 Mbit / s.
Since the moving image 1 is sent to the buffer 1 at 4 Mbit / s while recording on the disk, the buffer 1 has 7.2 Mbi.
t- (16-4) * 0.6 = 0.

On the other hand, the buffer 2 in which the moving image data 2 of 4 Mbit is stored in the buffer 2 at 4 Mbit / s.
Is sent, buffer 1 is 4 Mbit + 4
* 0.6 = 6.4 Mbit.

On the other hand, the buffer 3 having the moving image data 3 of 0.8 Mbit only transmits the moving image 2 to the buffer 2 at 4 Mbit / s.
it + 4 * 0.6 = 3.2 Mbit.

(7) In the next first 0.2 seconds, seeking from the recording area of the moving image 1 to the recording area of the moving image 2 is performed, so that the moving image is stored in each buffer and the capacity is 4 Mbi.
t / s * 0.2 = 0.8 Mbit is increased. That is, the buffer 1 has 0 + 0.8 = 0.8 Mbit, the buffer 2 has 6.4 + 0.8 = 7.2 Mbit, and the buffer 3 has 3.2 + 0.8 = 4 Mbit.
(8) In the next 0.6 seconds, the buffer 1 having the moving image data 1 of 0.8 Mbit only sends the moving image 1 to the buffer 1 at 4 Mbit / s.
Mbit + 4 * 0.6 = 3.2 Mbit. on the other hand,
The 7.2 Mbit video data 2 in the buffer 2 is 1
4Mbit / s while recording on disk at 6Mbit / s
The moving image 2 is sent to the buffer 2 at
Is 7.2 Mbit-16-4) 3 * 0.6 = 0.

On the other hand, the buffer 3 having the moving image data 3 of 4 Mbit is stored in the buffer 3 at 4 Mbit / s.
Is sent, buffer 3 is 4 Mbit + 4
* 0.6 = 6.4 Mbit.

(9) In the next first 0.2 seconds, a seek operation is performed from the recording area of the moving image 2 to the recording area of the moving image 3, so that the moving image is stored in each buffer, and the capacity is 4 Mb.
it / s * 0.2 = 0.8 Mbit. That is, the buffer 1 has 3.2 + 0.8 = 4 Mbit, the buffer 2 has 0 + 0.8 = 0.8 Mbit, and the buffer 3 has 6.4 + 0.8 = 7.2 Mbit.

(10) The next 0.6 seconds is 0.8 Mbit
Buffer 1 with moving image data 1 of 4 Mbit / s
, The moving image 1 is merely sent to the buffer 1, and therefore the buffer 1 has 4Mbit + 4 * 0.6 = 6.4Mbit. On the other hand, the buffer 2 having the moving image data 2 of 0.8 Mbit is 0.8 Mbit + 4 * 0.6 = 32 Mbit
Becomes On the other hand, while the 7.2 Mbit moving image data 3 in the buffer 3 is recorded on the disk 4 at 16 Mbit / s, the moving image 3 is sent to the buffer 3 at 4 Mbit / s, so that the buffer 3 has 7.2 Mbit- (16-4). ) * 0.6
Becomes Hereinafter, (5), (6), (7), (8),
(9) and (10) are repeated.

Thus, the three access times and the other two
Each digital moving image to be recorded in the recording of one moving image on the disk is stored in each buffer memory. At the time of recording on each disk, the moving image data in the buffer memory is recorded on the disk. Digital moving images delivered by repeating these steps are continuously recorded on the optical disk without loss.

In the above-described embodiment, a case has been described in which digital video data of two systems and three systems are simultaneously recorded. However, the present invention is extended to simultaneous recording of digital video data of n systems (n> 3). It is possible.

In this case, the digital moving image data of n systems is recorded in n recording areas having different radial positions on the optical disk at every T seconds. Since the recording for n T seconds and the seek (access) for n times are performed in one time division sequence, the necessary recording speed is (n * T + nS) * A / T (bp).
s) or more, and the required buffer memory capacity is (n * n)
S + nT) * A bits or more. It is clear from the gist of the present invention that under these conditions, the input n-system digital moving image data can be recorded without interruption.

In this embodiment, a semiconductor memory of another chip may be used as the first and second buffer memories 14 and 24. However, a large-capacity semiconductor memory of one chip is used, and its address space is divided into two. Each first
And storage of the second digital moving image data.

As described above, according to the present invention, recording of different digital moving image data in a plurality of recording areas having different radial positions on a disc-shaped recording medium is alternately performed using a single recording / reproducing head. By performing in a time-sharing manner, 1
It becomes possible to record a plurality of digital moving images on one video disk device without deteriorating the image quality.

Specifically, in the above embodiment, the recording speed of the recording medium is set to the sum of the bit rates of the first and second digital moving image data, and the recording / reproducing head sets the first recording area and the second recording area. It is faster than the bit rate including the reciprocating access time, and the recording / reproducing head is in the first digital moving image data recording system during the recording of the second digital moving image data and in the first recording area and the second recording area. A first buffer memory having a capacity for storing first digital moving image data input at the time of reciprocating access to the area is provided, and a first digital moving image data recording system is provided with a first buffer memory.
A second buffer having a capacity for storing second digital moving image data input during recording of the digital moving image data and at the time when the recording / reproducing head makes reciprocal access between the first recording area and the second recording area. By providing the memory, the input first and second digital moving image data can be continuously and simultaneously recorded on the recording medium by one recording / reproducing head without loss.

FIG. 7 shows the configuration of a video disk device according to another embodiment of the present invention. This video disk device includes a first and second analog image input units 111, an MPEG encoder 1 as a digital moving image data compressor.
12, a digital image input unit 113, first and second buffer memories 114 and 115, a switch 116, a modulator / demodulator 117, an optical head 118, an optical disk 119, and a digital moving image data expander MP for image monitoring.
EG decoders 120 and 121, monitor 122 for displaying a reproduced image, and controller 1 for controlling each unit
23.

Hereinafter, the operation of the present embodiment will be described.

In the following description, the bit rate of digital moving image data distributed from the MPEG encoder 112, CATV, satellite broadcasting, etc. is 4M on average.
bps. The recording / reproducing speed (data transfer speed) of the digital moving image data on the optical disk 119 is 12 Mbps. Further, the optical disc 119 is shown in FIG.
, The first and second radial positions are different.
Recording areas 131 and 132. The capacities of the first and second buffer memories 114 and 115 are both 6 Mbits.

In the following operation, the optical head 118 will be described.
Playback from optical disk 119 by buffer memory 1
Writing / reading of the switches 14 and 115 and switching control of the switch 116 are all performed under the control of the controller 123.

Since the recording operation in this embodiment is substantially the same as the previous embodiment, the reproduction operation will be described.

First, a description will be given of the operation in the case of reproducing normal one-system digital moving image data. Here, a case where the first digital moving image data recorded in the first recording area 131 on the optical disc 119 is reproduced will be described.

First recording area 13 on optical disc 119
The reproduction signal reproduced from 1 by the optical head 118 is demodulated by the modem 117 into first digital moving image data. The demodulated digital video data is supplied to the switch 1
After that, the data is written into the buffer memory 114 at a speed of 12 Mbps. At the same time, the buffer memories 114 to 4
Digital moving image data is read out at a speed of Mbps, decompressed by the MPEG decoder 120, and read by the monitor 122.
Is output to

Since the reproduction speed of the optical disk 119 is higher than the bit rate of the digital moving image data, the buffer memory 114 may become full. In this case, the digital moving image data stored in the buffer memory 114 is reduced to an appropriate amount. Playback is interrupted until. Therefore, reading of digital moving image data from the buffer memory 114 is performed continuously, but reproduction of digital moving image data from the optical disk 119 is performed intermittently.

For example, when the digital video data stored in the buffer memory 114 becomes 2 Mbits or less,
It is assumed that reproduction from the optical disk 119 is performed. In this case, while digital moving image data is written to the buffer memory 114 at a speed of 12 Mbps, 4 Mbps
Since the digital moving image data is read from the buffer memory 114 at the speed of s and is input to the MPEG decoder 120, the buffer memory 114 requires 2M in about 0.5 seconds.
Bit + (12 Mbps−4 Mbps) * 0.5 seconds = 6
It becomes full with M bits, and playback is interrupted. Since the buffer memory 14 becomes 2 Mbits in the next one second, digital moving image data is reproduced from the optical disk 119 again.

As described above, when one system of digital moving image data is reproduced, there is a period in which reproduction is suspended, and the reproduction of another system of digital moving image data can be performed using this time. it can.

Next, the operation when the first and second digital moving image data are simultaneously reproduced from the optical disk 119 will be described.

As described above, the optical disc 119 is the first optical disc.
During reproduction of the digital moving image data, there is a period in which the reproduction is interrupted, and the reproduction of the second digital moving image data is performed using this time.

The reproduction of the second digital moving image data is also performed as follows.
The reproduction is performed in the same manner as the reproduction of the first digital moving image data described above. That is, a reproduced signal reproduced from the second recording area 132 on the optical disk 119 by the optical head 118 is demodulated into second digital moving image data by the modem 117, and is transferred to the second buffer memory 115 via the switch 116. The data is written, decompressed by the MPEG decoder 121, and output to the monitor 122.

Here, as shown in FIG. 8, the first recording area 13 in which the first digital moving image data is recorded.
The second recording area 132 in which the first and second digital moving image data are recorded has different radial positions on the optical disc 119. Therefore, the recording area 13 of the optical head 118
Movement between 1,132, that is, access is required. The first and second digital moving image data to be input to the MPEG decoders 120 and 121 during access between the recording areas 131 and 132 are previously stored in the buffer memories 114 and 1.
15 are used.

FIG. 9 is a flowchart showing a processing procedure for simultaneously reproducing the first and second digital moving image data in the present embodiment. First, it is checked whether the first digital moving image data stored in the first buffer memory 114 is 4 Mbits or less (step S1).
If the digital moving image data stored in the first buffer memory 114 is 4 Mbits or less, the optical head 118 is moved to the first recording area 13 of the optical disc 119.
1 (step S2). Then, the digital moving image data is reproduced from the first recording area 131 and written into the buffer memory 114 until the first digital moving image data in the buffer memory 14 becomes 4 Mbits or more (steps S3 to S4).

Next, the optical head 118 is moved to the optical disk 119.
To the second recording area 132 (step S5),
Until the second digital moving image data in the second buffer memory 115 becomes 4M bits or more, the second recording area 1
The digital moving image data is reproduced from 32 and written into the buffer memory 115 (steps S6 to S7).

Thereafter, the flow returns to step S2, and the optical disk 1
The reproduction of the first digital moving image data from the first recording area 131 and the second reproduction from the second recording area 132
Is alternately repeated.

FIGS. 10A and 10B show the first and second buffer memories 114 and 115 during the simultaneous reproduction of the first and second digital moving image data in this embodiment.
FIG. 5 is a diagram showing a temporal change of a digital moving image data amount in FIG. In this example, the first and second recording areas 131,
The average of the access time between 132 is 0.25 seconds. It is also assumed that the optical head 118 is located in the first recording area 131. The operation at the time of simultaneous reproduction in this embodiment will be described in detail step by step with reference to FIG. It is assumed that the buffer memories 114 and 115 do not initially store digital moving image data.

(1) First, during the first 0.5 seconds, the first digital moving image data is reproduced from the first recording area 131 of the optical disc 119 at a speed of 12 Mbps, and is written into the first buffer memory 114. Since the data is read at a speed of 4 Mbps and output to the MPEG decoder 120, the first digital moving image data in the buffer memory 114 is (12 Mbps−4 Mbps) * 0.5 seconds =
4 Mbits. Since the reproduction is not performed from the second recording area 132 of the optical disc 119, the content of the first buffer memory 115 remains 0.

(2) In the next 0.25 seconds, the optical head 1
18 from the first recording area 131 to the second recording area 132
To access. During this access, reproduction from the optical disk 119 is not performed, and the first digital moving image data in the first buffer memory 114 is 4 Mbp.
s, and is output to the MPEG decoder 20, so that 4M bits-4Mbps * 0.25 seconds = 3M
And the content of the second buffer memory 115 is 0
Remains.

(3) During the next 0.5 second, the second digital moving image data is transferred from the second recording area 132 to 12 Mbp.
s, and is read out at a speed of 4 Mbps while being written to the second buffer
Since the data is output to the decoder 121, the buffer memory 11
5 is (12 Mbps).
−4 Mbps) * 0.5 seconds = 4 Mbits. No reproduction is performed from the first recording area 131 of the optical disc 119, and the first digital moving image data in the first buffer memory 114 is read at a speed of 4 Mbps and
Since it is output to the EG decoder 120, 3M bits-4
Mbps * 0.5 seconds = 1 Mbit.

(4) In the next 0.25 seconds, the optical head 1
18 from the second recording area 132 to the first recording area 131
To access. During this access, reproduction from the optical disk 119 is not performed, and the first digital moving image data in the first buffer memory 114 is 4 Mbp.
s, and is output to the MPEG decoder 120, so that 1 Mbit−4 Mbps * 0.25 sec = 0
And the second digital moving image data in the second buffer memory 115 is read out at a rate of 4 Mbps and
Since the data is output to the PEG decoder 121, 4 Mbits-
4 Mbps * 0.25 seconds = 3 Mbits.

(5) During the next 0.5 second, the first digital moving image data is transferred from the first recording area 131 to 12 Mbp.
s, and is read out at a speed of 4 Mbps while being written to the first buffer
Output to the decoder 120, the buffer memory 11
4 is (12 Mbps).
−4 Mbps) * 0.5 seconds = 4 Mbits. No reproduction is performed from the second recording area 132 of the optical disc 119, and the second digital moving image data in the second buffer memory 115 is read out at a speed of 4 Mbps and
Since it is output to the EG decoder 121, 3M bits-4
Mbps * 0.5 seconds = 1 Mbit.

(6) In the next 0.25 seconds, the optical head 1
18 from the first recording area 131 to the second recording area 132
To access. During this access, reproduction from the optical disk 119 is not performed, and the first digital moving image data in the first buffer memory 114 is 4 Mbp.
s, and is output to the MPEG decoder 20, so that 4M bits-4Mbps * 0.25 seconds = 3M
The second digital moving image data in the second buffer memory 115 is read at a speed of 4 Mbps and output to the MPEG decoder 121, so that 1 Mbit−4 Mbps × 0.25 seconds = 0.

(7) For the next 0.5 second, the second digital moving image data is transferred from the second recording area 132 to 12 Mbp.
s, and is read out at a speed of 4 Mbps while being written to the second buffer
Since the data is output to the decoder 121, the buffer memory 11
5 is (12 Mbps).
−4 Mbps) * 0.5 seconds = 4 Mbits. No reproduction is performed from the first recording area 131 of the optical disc 119, and the first digital moving image data in the first buffer memory 114 is read at a speed of 4 Mbps and
Since it is output to the EG decoder 120, 3M bits-4
Mbps * 0.5 seconds = 1 Mbit.

Thereafter, the access of the optical head 118 from the second recording area 132 to the second recording area 131 (0.25
Second) → reproduction of the first digital moving image data from the first recording area 131 (0.5 second) → first recording area 131
, The access of the optical head 118 to the second recording area 132 (0.25 seconds) → the reproduction of the second digital moving image data from the second recording area 132 (0.5 seconds) is repeated.

As can be seen from FIGS. 10A and 10B, the first digital moving image data in the first buffer memory 114 and the second digital moving image data in the second buffer memory 115 are both This shows that the reproduction of the first and second digital moving image data from the optical disk 119 is performed alternately without exceeding the buffer memory capacity.

Next, the reproduction speed of the optical disk 119 required in the present invention will be described. The average bit rate of the first and second digital moving image data in this embodiment is A = 4 bps, and the maximum access time of the optical disk 119 (the seek time required for the optical head 118 to move from the innermost circumference to the outermost circumference). (The time obtained by adding the time required for the optical disc 19 to make one rotation) is S = 0.25 seconds.

In order to simultaneously reproduce the first and second digital moving image data from the first and second recording areas 131 and 132 of the optical disk 119 with one optical head 118, two systems of digital moving image data are used. It is necessary to perform data reproduction alternately in a time-division manner and at a speed not lower than the average bit rate of the two systems of digital video data. That is, the first digital moving image data is reproduced for a certain time, and the second digital moving image data is reproduced for a certain time. Therefore, in order to process two systems of digital moving image data at an average bit rate of 4 Mbps, Is
At least 2 * 4 Mbp playback speed of optical disc 119
It is necessary to set s = 8 Mbps or more.

Further, the number of the optical head 118 is one, and the first and second recording areas 13 on the optical disc 119 are provided.
Since the positions of the recording areas 131 and 132 are not always the same, an access time between the recording areas 131 and 132 occurs when the area to be reproduced is switched. For example, “reproduction of first digital moving image data from first recording area 131” → “access from first recording area 131 to second recording area 132” →
When recording is performed by repeating a time-division procedure consisting of “reproduction of second digital moving image data from second recording area 132” → “access of second recording area 132 to first recording area 131”. , Two accesses occur in one time-sharing procedure. Therefore, during reproduction, the digital moving image data to be reproduced between the reproduction time and the two accesses is read out from the optical disk 119 during the reproduction time of the digital moving image data on the optical disk 119 of 0.5 second on average. It must be stored in the buffer memory.

From FIGS. 10A and 10B, the average reproduction time of the first digital moving image data per one time is 0.5.
Second, and that of the second digital moving image data is also 0.0.
5 seconds. The average access time is 0.25 seconds. Therefore, the reproduction speed of the optical disc 119 is (0.5
+ 0.5 + 2 * 0.25) * 4 Mbps / 0.5 second = 1
What is necessary is just 2 Mbps or more. Here, 4 Mbps is 2
This is the increment of the playback speed required for each access. The recording and reproducing speed of the optical disc 119 in this embodiment is 12 Mb.
ps, which satisfies this condition.

Next, the buffer memory capacity required in the present invention will be described. First, the capacity required for the first buffer memory 114 is twice the maximum access time S (the reciprocating time of the optical head 118 between the first recording area 31 and the second recording area 32) and the second digital A value obtained by multiplying the sum of the average reproduction time T2 of the moving image data by the average transfer speed of the digital moving image data, and is (2S + T2) * A bits or more. In this case, (2 * 0.25 + 0.5) *
4 = 4M bits or more.

Similarly, the capacity required for the second buffer memory 115 is twice the maximum access time S (the round trip time of the optical head 118 between the second recording area 32 and the first recording area 131). The sum of the average of the first digital moving image data and the average reproduction time T1 is multiplied by the average transfer speed of the digital moving image data, and is equal to or more than (2S + T1) * A bits. In this case, (2 * 0.25 + 0. 5) * 4 = 4M bits or more.

Therefore, the required buffer memory capacity is the first
And a total of 8 for the second buffer memories 114 and 115
M bits or more. In the present embodiment, the first and second
Since both of the buffer memories 114 and 115 have 6 Mbits and a total of 12 Mbits, this condition is satisfied.

However, referring to FIGS. 10A and 10B, the first
And the second buffer memories 114 and 115 have a maximum of 4
Since only M bits are used, it is understood that the capacity may be 4 M bits. Therefore, the buffer memory 11
The capacity of 4,115 can be 4 Mbits depending on the memory control.

After satisfying the conditions of the reproduction speed of the optical disk 119 and the buffer memory capacity, the first digital moving image data reproducing system
The optical head 118 accesses the first to second recording areas 132 to reproduce the second digital moving image data on average for 0.5 seconds.
The first digital moving image data to be output to the MPEG decoder 120 while the optical head 118 is being accessed at the radial position for subsequent reproduction from the optical disk 119 for an average of 0.5 seconds from the optical disk 119 during the reproduction.
When the optical head 118 accesses and when the second digital moving image data is reproduced from the optical disk 119, the digital moving image data is read from the first buffer memory 114 and output to the MPEG decoder 120. The image of the first digital moving image data can be reproduced without interruption.

On the other hand, in the reproduction system for the second digital moving image data, the second recording area 132 to the first recording area 1
The first digital moving image data is reproduced for an average of 0.5 seconds by accessing the optical head 118 to the optical disk 31, and the optical head 118 is moved to a radial position from the first recording area 131 to the second recording area 132 where reproduction is continued. MPEG while accessing
The second digital moving image data to be output to the decoder 121 is stored in advance in the second buffer memory 115 at the time of reproduction from the optical disk 119 for an average of 0.5 seconds. When data is reproduced from the optical disk 119, the digital moving image data is read out from the second buffer
By outputting to the EG decoder 121, the image of the second digital moving image data can be reproduced without interruption.

By such an operation, the optical disk 11
First and second recording areas 13 at different radial positions on the recording medium 9
1, 132, the first and second digital moving image data can be simultaneously reproduced by one optical head 118.

In the present embodiment, as shown in FIG. 11, the display screen 140 of the monitor 122 is divided into two, and a reproduced image 141 of the first digital moving image data and a reproduced image 141 of the second digital moving image data are reproduced. By dividing the image 42 and displaying it at the same time, the two systems of reproduced images 141 and 14 are displayed.
2 can be monitored simultaneously.

In this monitor display, the first and second digital moving image data read from the buffer memories 114 and 115 are used in the present embodiment for the monitor display.
After being decompressed at 20, 121, it is output to the monitor 122, but when the input moving image signal is analog, it is directly passed through the MPEG encoder 112, digital image input unit 113 and MPEG decoder 120. The information may be input to the monitor 122.

[0157] Because the address information recorded on the optical disk 119 can be read, the optical disk 119 can be read.
Movement from a certain recording area to another recording area, that is, a seek may fail. In such a case, the video disk device according to the present embodiment seeks again up to the retry count included in advance. In consideration of the retry when the seek fails, the bit rate of the digital moving image data is set to A (bps), and the maximum access time to the optical disk 119 (the optical head 118 seeks from the innermost circumference to the outermost circumference of the optical disk 119). One optical disc 119 at time
The rotation time) is S seconds, and the maximum number of retries in case of a seek failure is N, and the seek time is (N + 1) * S seconds, and the playback speed of the optical disk 119 and the buffer memory 114, 115 may be estimated.

Accordingly, the reproduction speed of the first digital moving image data is (T1 + T2 + 2 * S * (N + 1)) * A
/ T1 (bps) or more, the reproduction speed of the second digital moving image data is (T1 + T2 + 2 * S * (N + 1)) *
A / T2 (bps) or more, buffer memory 114, 1
The total of the 15 storage capacities is (4 * S * (N + 1) + T1 +
T2) If the number of bits is equal to or more than the A bit, the digital moving image data during the most seek operation can be stored in the buffer memories 114 and 115 even if the seek of the optical head 118 is retried. Obviously, it can be played back without interruption.

In the above-described embodiment, the case where two systems of digital video data are reproduced simultaneously has been described.
Next, the simultaneous reproduction of three systems of digital moving image data will be described.

FIG. 12 is an example showing a time change of a digital moving image in the buffer memory corresponding to each moving image when three moving images are reproduced simultaneously. There are three buffer memories corresponding to each moving image, the average bit rate of the moving image is A = 4 Mbit / 8, and the maximum access time is S
= 0.2 seconds, T1 = T2 = T3 = 0.6 seconds.

The recording speed required for simultaneously reproducing three moving images is (T1 + T2 + T3 + 3 * S) * A / T
1 = 16 Mbps or more. The required buffer memory is (3 * S + T1 + T
2) * A = 7.2 Mbit, three buffer memories 2,
The total of three becomes 7.2 * 3 = 21.6 Mbit. This 3
The two buffers 1, 2, and 3 correspond to the moving images 1, 2, and 3, respectively.

(0) For the first 0.6 seconds, the moving image 1 is reproduced from the disk at 16 Mbit / s while
Since the moving image 1 is read from the buffer 1 at Mbit / s, the buffer 1 is (16-4) * 0.6 = 7.2 Mbi
t.

The buffers 2 and 3 remain at 0 bit because there is no reproduction from the disk.

(1) In the next first 0.2 seconds, a seek is performed from the reproduction area of the moving image 1 to the reproduction area of the moving image 2.
The moving image 1 is read from the buffer 1 at 4 Mbit / s, and the capacity of the buffer 1 is 7.2 Mbit-4 Mbit / s *
0.2 = 6.4 Mbit. Buffers 2 and 3 remain at 0.

(2) During the next 0.6 seconds, the moving image 2 is played back from the disk at 16 Mbit / s in the buffer 2 at 4 Mb.
Since the moving image 2 is read from the buffer 2 at it / s, the buffer 2 is (16-4) * 06 = 7.2 Mbit
Becomes On the other hand, the moving image 1 from the buffer 1 is 4 Mbit /
s and the capacity of the buffer 1 is 6.4 Mbit-
4Mbit / s * 0.6 = 4Mbit. Cross 7 remains at 0.

(3) In the next first 0.2 seconds, the reproduction area of the moving image 3 is sought from the reproduction area of the moving image 2. The moving images 1 and 2 are read from the buffers 1 and 2 at 4 Mbit / s, and the capacity of the buffer 1 is 4 Mbit−4 Mbit / s.
s * 0.2 = 3.2 Mbit, and the capacity of the buffer 2 is 7.2 Mbit−4 Mbit / s * 0.2 = 6.4.
Mbit.

(4) In the next 0.6 seconds, the moving image 3 is reproduced in the buffer 3 at 16 Mbit / s from the disk at 4 Mb.
Since the moving image 3 is read from the buffer 3 at it / s, the buffer 3 becomes (16-4) * 0.6 = 7.2 Mbit. On the other hand, moving images 1 and 2 are 4 Mb from buffers 1 and 2.
It is read at it / sP, and the capacity of the buffer 1 is 3.2
Mbit−4 Mbit / s * 0.6 = 0.8 Mbit, and the capacity of the buffer 2 is 6.4 Mbit−4 Mbi
t / s * 0.6 = 4 Mbit.

(5) In the next first 0.2 seconds, seeking from the reproduction area of the moving image 3 to the reproduction area of the moving image 1 is performed.
Moving images 1, 2, and 3 are 4 Mbit from buffers 1, 2, and 3.
/ S read out at a capacity of 0.8 Mbit
−4 Mbit / s * 0.2 = 0 Mbit, and the capacity of the buffer 2 is 4 Mbit−4 Mbit / s * 0.2 =
3.2 Mbit, and the capacity of the buffer 3 is 7.2 Mbit.
bit−4 Mbit / s * 0.2 = 6.4 Mbit.

(6) In the next 0.6 seconds, the moving image 1 is reproduced at 16 Mbit / s from the disk in the buffer 1 while the 4 Mb video is reproduced.
Since the moving image 1 is read from the buffer 1 at it / s, the buffer 1 has (16-4) * 0.6 = 7.2 Mbit. On the other hand, the moving images 2 and 3 are 4 Mb from the buffers 2 and 3.
It is read at it / s, and the capacity of the buffer 2 is 3.2M
bit−4 Mbit / s * 0.6 = 0.8 Mbit, and the capacity of the buffer 3 is 6.4 Mbit−4 Mbit
/S*0.6=4 Mbit.

(7) In the next first 0.2 seconds, seeking from the reproduction area of the moving image 1 to the reproduction area of the moving image 2 is performed.
Moving images 1, 2, and 3 are 4 Mbit from buffers 1, 2, and 3.
/ S read out at a rate of 7.2 Mbits.
−4 Mbit / s * 0.2 = 6.4 Mbit, and the capacity of the buffer 2 is 0.8 Mbit−4 Mbit / s *
0.2 = 0 Mbit, and the capacity of the buffer 3 is 4 M
bit−4 Mbit / s * 0.2 = 3.2 Mbit.

(8) In the next 0.6 seconds, the moving image 2 is reproduced from the disk in the buffer 2 at 16 Mbit / s while 4 Mb
Since the moving image 2 is read from the buffer 2 at it / s, the buffer 2 has (16-4) * 0.6 = 7.2 Mbit. On the other hand, moving pictures 1 and 3 are 4 Mbi from buffers 1 and 3
The capacity of the buffer 1 read at t / s is 6.4 Mbi
t-4Mbit / s * 0.6 = 4Mbit, and the capacity of the buffer 3 is 3.2Mbit-4Mbit / s *
0.6 = 0.8 Mbit.

(10) In the next 0.6 seconds, while reproducing the moving image 3 from the disk at 16 Mbit / s,
Since the moving image 3 is read from the buffer 3 at Mbit / s, the buffer 3 is (16-4) * 0.6 = 7.2 Mbi
t. On the other hand, moving images 1 and 2 are
It is read at Mbit / s, and the capacity of buffer 1 is 3.
2Mbit-4Mbit / s * 0.6 = 0.8Mbit
And the capacity of the buffer 2 is 6.4 Mbit-4Mi
t / s * 0.6 = 4 Mbit. After (5),
(6), (7), (8), (9), and (10) are repeated. In this manner, when reproducing from each disc, in addition to the moving image corresponding to the reproducing time, three access times and other two
A moving image corresponding to the time to be reproduced during reproduction of one moving image from the disk is reproduced from the disk and stored in the buffer memory, and the access time is three times and the other two moving images are to be reproduced during reproduction on the disk. The digital moving image is called from the buffer memory. The three digital moving images reproduced by repeating these operations are continuously reproduced from the disc without loss.

Further, the conditions of recording, reproduction speed and buffer capacity of the recording medium in the case of retrying a maximum of N times when a seek fails, can be obtained by converting the maximum access time S as (N + 1) * S seconds. In both the simultaneous recording of the moving images and the simultaneous reproduction of the three moving images, the first recording speed is set to (T1 + T2).
+ T3 + 3 * S * (N + 1)) * A / T1 bps or more and the second reproduction speed is (T1 + T2 + T3 + 3 * S *
(N + 1)) * A / T2 bps or more, and the third reproduction speed is (T1 + T2 + T3 + 3 * S * (N + 1)) * A /
T2 bps or more, and the total recording capacity of the recording buffer memory is (9 * S * (N + 1) + 2 * T1 + 2 * T2 +
2 * T3) * A bits or more.

In the above-described embodiment, a case has been described where digital video data of two systems and three systems are reproduced simultaneously. However, the present invention is extended to the simultaneous reproduction of n (n> 3) digital video data. It is possible.

In this case, n pieces of digital moving image data are reproduced from n pieces of recording areas having different radial positions on the optical disk at every T seconds. Since the reproduction for n T seconds and the seek (access) for n times are performed in one time division sequence, the required reproduction speed is (n * T + nS) * A / T (bp)
s) or more, and the required buffer memory capacity is (n * n)
S + nT) * A bits or more. It is clear from the gist of the present invention that under these conditions, the digital moving image data of n systems can be reproduced without interruption of the image.

In the above-described simultaneous recording of three moving images and simultaneous reproduction of three moving images, the recording / reproducing speed and buffer memory conditions are the same. This means that simultaneous reproduction and recording of three moving images may be combined. The simultaneous recording and reproduction is described in detail in Japanese Patent Application No. 9-66370.
Simultaneous recording and reproduction of any combination of recordings is possible.

That is, the recording digital continuous data is stored in the buffer when the recording / reproducing head accesses between the recording area and the reproducing area on the recording medium when recording on the recording area and reproducing from the reproducing area. At the time of writing to the memory and recording on the recording area, the digital continuous data for recording stored in the buffer memory is read at a recording speed of at least twice the average bit rate of the digital continuous data for recording, and is recorded on the recording area and reproduced. At the time of reproduction from the area, the digital continuous data recorded in the reproduction area is reproduced at a reproduction speed of twice or more of the average bit rate and written into the buffer memory, and at the time of recording to the recording area and from the reproduction area. At the time of reproduction, and while the recording / reproduction head is accessing between the recording area and the reproduction area on the recording medium, the reproduction buffer memory Digital continuous data stored is read at a predetermined bit rate performs control to output to the display device.

When recording in the recording area and reproduction from the reproduction area are alternately performed in a time-division manner, the average recording time per time is T1 seconds, the average reproduction time is T2 seconds, and the maximum access time of the recording medium ( The seek time required for the recording / reproducing head to move from the innermost circumference to the outermost circumference of the recording medium plus the time required for the recording medium to make one revolution) is S seconds, and the average bit rate of the input digital continuous data is A. (Bps), the recording speed is (T1 + T2 + 2S) * A / T1 bps
As described above, the reproduction speed is (T1 + T2 + 2S) * A / T
2 bps or more, and the total storage capacity of the recording buffer memory and the reproduction buffer memory is set to (4 * S
+ T1 + T2) * Set to A bit or more.

Subsequently, the present invention is extended to the recording and reproduction of m moving images.

The average bit rate of the digital moving picture to be recorded or reproduced is set to Abit / s, and the maximum access time of the video disk (the time for the recording / reproduction head to seek from the innermost circumference to the outermost circumference plus the time for moving the disk 1 or more). Time) is S seconds. First, consider simultaneous recording of m moving images. In order to simultaneously record m digital moving images with one recording / reproducing head, it is necessary to record m moving images on a disc at a rate not lower than the average bit rate of the m digital moving images in a time division manner. There is. One time,
The moving image 1 is recorded on the disk, the moving image 2 is recorded on the disk for a certain time, and the m moving images are recorded for a certain time. In order to process m moving images, m
* A disk recording / reproducing speed of Abit / s or more is required. Furthermore, since there is only one recording / reproducing head, and the position of each recording area on the disc is not always the same, an access time between the areas is required to switch between the respective recording areas. For example, “Recording of T1 second” → “Accessing S seconds from recording area 1 to recording area 2” → “Recording of T2 seconds” →
"Access from recording area 2 to recording area 3 for S seconds" →
“T3 seconds recording” → “S from recording area 3 to recording area 4”
Second access] → “S second access from recording area m−1 to recording area m” → “Tm second recording” → “recording area m
When the recording and reproduction are performed by repeating the time-sharing procedure consisting of “S seconds access to recording area 1”, m times of access occur in one time-sharing procedure.

Therefore, at the time of the first recording, the input digital moving image data for (T1 + T2 + T3 +... + Tm + m * S) seconds is recorded during T1 seconds, so that the recording speed of the first moving image is recorded. Is (T1 + T2 + T3 + ...
Ten Tm + m * S) * A / T1 (bps) or more. Similarly, the recording speed of the second moving image is (T1 + T2 + T3 +...
+ Tm + m * S) * A / T2 (bps) or more, and the recording speed of the third moving image is similarly (T1 + T2 + T3 +... + Tm).
+ M * S) A / T3 (bps),..., The recording speed of the m-th moving image is similarly (T1 + T2 + 1 +... + Tm + m * S)
* A / Tm (bps).

On the other hand, the required buffer memory capacity is m times the access time (recording area 1 and recording area 2, recording area 3,..., The reciprocating time of optical head movement in recording area m) and other m The buffer memory required for each moving image at a value obtained by multiplying the sum of the recording time of one moving image by the average transfer speed of the moving image is (m * S + T2
+ T3 +... + Tm) Abit or more, and the second moving image is (m
* S + T1 + T3 + T4 + ... + Tm) * Abit or more
The third moving image is (m * S + T1 + T2 + T4 +... + T
m) * Abit or more, and the m-th moving image is (m * S + T1 +
T2 + T3 +... + Tm _-1 ) * Abit or more is required.

Therefore, a total of (m * m * S + (m-1)
(T1 + T2 + T3 +... + Tm)) * Abit or more. If the conditions of the recording / reproducing speed and the buffer capacity of these disks are satisfied, the access time of m times and each digital moving image to be recorded during the recording of m-1 other moving images on the disk are recorded in the buffer memory. Is done. It is recorded on the disc when recording on each disc. Digital moving images delivered by repeating these steps are continuously recorded on the optical disk without any loss.

Although the description so far has described recording, if recording is reworded, it is clear that the conditions for the reproduction speed from the disk and the reproduction buffer memory are the same.

That is, in addition to the moving image corresponding to the reproduction time when reproducing from each disk, the moving image corresponding to the m times of access time and the time to be reproduced when reproducing the other m-1 moving images from the disk are obtained. A digital moving image to be reproduced from the disk and stored in the buffer memory and to be reproduced during the m-times access time and the reproduction of the other m-one moving image to the disk is called from the buffer memory. The m digital moving images reproduced by repeating these operations are continuously reproduced from the optical disk without any loss. Further, the conditions of recording, reproduction speed and buffer capacity of the recording medium in the case of retrying a maximum of N times when a seek fails, can be obtained by converting the maximum access time S to (N + 1) S seconds. For both simultaneous recording and simultaneous playback of three moving images, the first recording speed is set to (T1 + T2 + T3 +.
+ Tm + m * S * (N + 1)) * A / T1 bps or more and the second reproduction speed is (T1 + T2 + T3 +... + Tm + m
* S * (N + 1)) * / T2 bps or more, and set the third reproduction speed to (T1 + T2 + T3 +... + Tm + m * S * (N +
1)) * A / T2 bps or more,..., M-th playback speed is (T1 + T2 + T3 +... + Tm + m * S * (N1)) *
A / T mbps or more, and the total recording capacity of the recording buffer memory is (m * m * S * (N + 1) + (m-1) * (T
1 + T2 + T3 +... + Tm) * A bits or more.

The simultaneous recording of m moving images and the simultaneous reproduction of m moving images have been described, but the recording / reproducing speed and buffer memory conditions are the same in both cases. This means that m moving images may be simultaneously reproduced and recorded. Simultaneous recording and reproduction is described in detail in Japanese Patent Application No. 9-66370, and by applying this to the present invention, simultaneous recording and reproduction of any combination of reproduction and recording of m moving images can be performed.

In the above embodiment, semiconductor memories of different chips may be used as the first and second buffer memories 114 and 115. However, a large-capacity semiconductor memory of one chip is used, and its address space is divided into two. Each of them may be used for storing the first and second digital moving image data.

Although the above embodiment has been described with reference to the case where the recording medium is an optical disk, it can be used in principle as long as data can be recorded / reproduced by a recording / reproducing head using a disk-shaped recording medium. For example, a magnetic disk device (hard disk device) or a floppy disk device may be used.

Further, the present invention can be applied not only to video devices but also to audio devices. In this case, the audio device stores the digital audio signal in the buffer memory, reads the digital audio signal from the buffer memory, and inputs the digital audio signal to the speaker via the D / A converter.

[0190]

As described above, according to the present invention, using a single recording / reproducing head, different digital moving image data can be reproduced from a plurality of recording areas having different radial positions on a disk-shaped recording medium. By alternately performing the processing in a time-sharing manner, it becomes possible to reproduce a plurality of types of digital moving images with one video disk device.

Specifically, in the present invention, the recording / reproducing head reciprocates the first recording area and the second recording area to the reproduction speed of the recording medium to the sum of the bit rates of the first and second digital moving image data. And the recording / reproducing head in the first digital moving image data reproducing system during the reproduction of the second digital moving image data and the first recording area and the second recording area. A first buffer memory having a capacity for storing first digital moving image data to be reproduced at the time of reciprocating access to the
The digital moving image data recording system includes a second digital moving image to be reproduced during reproduction of the first digital moving image data and at a time when the recording / reproducing head makes reciprocal access to the first recording area and the second recording area. By providing a second buffer memory having a capacity to store image data, the first and second digital moving image data can be stored without loss.
One recording / reproducing head can continuously and simultaneously reproduce from a recording medium.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a video disk device according to an embodiment of the present invention.

FIG. 2 is an exemplary view showing first and second recording areas on the optical disc in the embodiment.

FIG. 3 is a flowchart showing a processing procedure of simultaneous recording of first and second digital moving image data according to the embodiment;

FIG. 4 is a diagram showing a change in the amount of digital moving image data in first and second buffer memories according to the embodiment;

FIG. 5 is an exemplary view showing a display example according to the embodiment;

FIG. 6 is a diagram showing a change in the amount of digital moving image data in first, second, and third buffer memories according to the embodiment;

FIG. 7 is a block diagram showing a configuration of a video disk device according to another embodiment of the present invention.

FIG. 8 is a diagram showing first and second recording areas on the optical disc in the embodiment.

FIG. 9 is an exemplary flowchart showing a processing procedure for simultaneously reproducing first and second digital moving image data according to the embodiment;

FIG. 10 is a view showing a change in the amount of digital moving image data in first and second buffer memories according to the embodiment;

FIG. 11 is an exemplary view showing a display example in the embodiment.

FIG. 12 is a diagram showing a change in the amount of digital moving image data in first, second, and third buffer memories according to the embodiment;

[Explanation of symbols]

 11 first analog image input unit 12 MPEG encoder 13 digital image input unit 14 first buffer memory 15 MPEG decoder 21 second analog image input unit 22 MPEG encoder 23 digital image input unit 24 ... second buffer memory 25 ... MPEG decoder 31 ... switch 32 ... modulator / demodulator 33 ... optical head 34 ... optical disk 35 ... monitor 36 ... controller 111 ... analog image input unit 112 ... MPEG encoder 113 ... digital image input unit 114 ... first 1 buffer memory 115 ... second buffer memory 116 ... switch 117 ... modulator / demodulator 118 ... optical head 119 ... optical disc 120,121 ... MPEG decoder 122 ... monitor 123 ... controller

Claims (20)

[Claims] 1. A disk device for recording and reproducing digital continuous data by a recording / reproducing head using a disk-shaped recording medium, wherein each of the first and second digital continuous data to be inputted is temporally stored. First and second buffer memories, and recording of the first and second digital continuous data in first and second recording areas having different radial positions on the recording medium in a time-division manner. Control means for performing the following control: the control means, at the time of recording the second digital continuous data, and while the recording / reproducing head is accessing between the first recording area and the second recording area The input first digital continuous data is written into the first buffer memory, and the first digital continuous data is recorded and recorded / reproduced. And writing the second digital continuous data to the second buffer memory, the second digital continuous data being input while the disk is accessing between the first recording area and the second recording area, and recording the first digital continuous data. In some cases, the digital continuous data stored in the first buffer memory is read out at a recording speed at least twice the average bit rate of the input first digital continuous data and recorded in the first recording area, At the time of recording the second continuous digital data, the continuous digital data stored in the second buffer memory is read out at a recording speed that is at least twice the average bit rate of the first continuous digital data to be input and read. What is claimed is: 1. A disk device for performing control for recording in a second recording area. 2. The average recording per time of the first digital continuous data when the recording of the first and second digital continuous data in the first and second recording areas is performed alternately in a time division manner. The time is T1 seconds, the average recording time per second digital continuous data is T2 seconds, the maximum access time of the recording medium (the time when the recording / reproducing head moves from the innermost circumference to the outermost circumference of the recording medium). (The time obtained by adding the time required for the recording medium to make one rotation) to the seek time required for
When the average bit rate of the input first and second digital continuous data is A (bps) and the recording speed of the first digital continuous data is (T1 + T
2 + 2S) * A / T1 (bps) or more, and the recording speed of the second digital continuous data is (T1 + T2 + 2
2. The disk device according to claim 1, wherein the value is S) * A / T2 (bps) or more. 3. The average recording per time of the first digital continuous data when the recording of the first and second digital continuous data in the first and second recording areas is performed alternately in a time-division manner. The time is T1 seconds, the average recording time per second digital continuous data is T2 seconds, the maximum access time of the recording medium (the time when the recording / reproducing head moves from the innermost circumference to the outermost circumference of the recording medium). (The time obtained by adding the time required for the recording medium to make one rotation) to the seek time required for
Second, when the average bit rate of the input first and second digital continuous data is A (bps), the total storage capacity of the first and second buffer memories is (4 * S + Tl + T2) * A 3. The disk device according to claim 1, wherein the number of bits is equal to or more than a bit. 4. An average per one time of the first digital continuous data when the recording of the first and second digital continuous data in the first and second recording areas is performed alternately in a time-division manner. The recording time is Tl seconds, the average recording time per second digital continuous data is T2 seconds, the maximum access time of the recording medium (the recording / reproducing head is from the innermost circumference to the outermost circumference of the recording medium). The seek time required for the movement plus the time required for the recording medium to make one revolution) is S seconds, the average bit rate of the input first and second continuous digital data is A (bps), the seek failure When the maximum number of retries at time is N, the first
The recording speed of the first digital continuous data in the recording area of (T1 + T2 + 2 * S * (N + 1)) * A / Tl
(Bps) or more, and the second recording area
Of the continuous digital data of (T1 + T2 + 2
4. The disk device according to claim 1, wherein the value is set to * S * (N + 1)) * A / T2 (bps) or more. 5. An average per one time of the first digital continuous data when the first and second digital continuous data are recorded in the first and second recording areas alternately in a time-division manner. The recording time is T1 seconds, the average recording time per second digital continuous data is T2 seconds, and the maximum access time of the recording medium (the recording / reproducing head moves from the innermost circumference to the outermost circumference of the recording medium). S), the average bit rate of the input first and second digital continuous data is A (bps), and the average bit rate of the input first and second digital continuous data is A (bps). When the maximum number of retries is N, the first
And the total storage capacity of the second buffer memory as (4 *
5. The disk device according to claim 1, wherein the number of bits is at least S * (N + 1) + T1 + T2) * A bits. 6. A display screen of the display device is divided into an image of the first digital continuous data being recorded in the first recording rust area and a second image being recorded in the second recording area. 6. The disk device according to claim 1, wherein the image of the digital continuous data is displayed simultaneously. 7. A distor device for recording and reproducing digital continuous data by a recording / reproducing head using a disk-shaped recording medium, wherein the data is reproduced from first and second recording areas at different radial positions on the recording medium. First and second for temporarily storing first and second digital continuous data
A buffer memory, and control means for performing control for alternately performing the reproduction of the first and second digital continuous data in a time-division manner, wherein the control means reproduces the second digital continuous data. Time and the first digital continuous data to be reproduced while the recording / reproducing head is accessing between the first recording area and the second recording area is twice the average bit rate of the first digital continuous data. Reproducing from the first recording area at the above-described reproducing speed and writing the data in the first buffer memory, and when reproducing the first digital continuous data, the recording / reproducing head performs the first recording area and the second Of the second digital continuous data to be reproduced during the access between the recording areas of the second digital continuous data.
The digital continuous data stored in the first buffer memory is reproduced in advance from the second recording area and written to the second buffer memory at a reproduction speed of twice or more, and the first digital continuous data is reproduced. Is read out at the bit rate of the first digital continuous data. When the second digital continuous data is reproduced, the digital continuous data stored in the second buffer memory is read at the bit rate of the second digital continuous data. A disk device for performing reading control. 8. An average reproduction per time of the first digital continuous data when the reproduction of the first and second digital continuous data from the first and second recording areas is alternately performed in a time division manner. The time is T1 second, the average reproduction time per one time of the digital continuous data of the arm 2 is T2 seconds, the maximum access time of the recording medium (the locking / reproducing head moves from the innermost circumference to the outermost circumference of the recording medium). Is obtained by adding the time required for the recording medium to make one rotation to the seek time required for
Second, when the average bit rate of the first and second digital continuous data is A (bps), the reproduction speed of the first digital continuous data is (Tl + T2 + 2S).
* A / Tl (bps) or more, and the reproduction speed of the second digital continuous data is (Tl + T2 + 2S) * A / T
8. The disk device according to claim 7, wherein the disk device is set to 2 (bps) or more. 9. An average reproduction per time of the first digital continuous data when reproducing the first and second digital continuous data from the first and second recording areas alternately in a time division manner. The time is Tl seconds, the average reproduction time per second digital continuous data is T2 seconds, the maximum access time of the recording medium (the time when the recording / reproduction head moves from the innermost circumference to the outermost circumference of the recording medium). (The time obtained by adding the time required for the recording medium to make one rotation) to the seek time required for
Second, the average bit rate of the first and second digital continuous data is A (bps), and the total storage capacity of the first and second buffer memories is (4 * S +
9. The disk device according to claim 7, wherein T1 + T2) * A bits or more. 10. An average per unit time of the first digital continuous data when the reproduction of the first and second digital continuous data from the first and second recording areas is performed alternately in a time-division manner. The reproduction time is Tl seconds, the average reproduction time per second digital continuous data is T2 seconds,
The maximum access time of the recording medium (the seek time required for the recording / reproducing head to move from the innermost circumference to the outermost circumference of the recording medium plus the time required for the recording medium to make one rotation) is S seconds, Assuming that the average bit rate of the digital moving image data of the first and the yaw 2 is A (bps) and the maximum number of retries when a seek fails is N, the first digital continuous data from the first recording area The reproduction speed of (Tl + T2 + 2 * S * (N + 1)) * A / Tl (b
ps) or more, and the reproduction speed of the second digital continuous data from the second recording area is (Tl + T2 + 2 *).
10. The disk device according to claim 7, wherein the value of S * (N + 1)) * A / T2 (bps) or more is specified. 11. An average per one time of the first digital continuous data when the recording of the first and second digital continuous data from the first and second recording areas is performed alternately in a time division manner, respectively. The reproduction time is Tl seconds, the average reproduction time per second digital continuous data is T2 seconds,
The maximum access time of the recording medium (the seek time required for the recording / reproducing head to move from the innermost circumference to the outermost circumference of the recording medium plus the time required for the recording medium to make one rotation) is S seconds, Assuming that the average bit rate of the input first and second digital continuous data is A (bps) and the maximum number of retries in case of a seek failure is N, the storage capacity of the first and second buffer memories is Total (4
11. The distor device according to claim 7, wherein the number of bits is equal to or more than * S * (N + 1) + T1 + T2) * A bits. 12. A display screen of the display device is divided into an image of the first digital continuous data being reproduced from the first recording area and a second digital image being reproduced from the second recording area. 12. The disk device according to claim 7, wherein an image of digital continuous data is displayed simultaneously. 13. The digital continuous data according to claim 1, wherein
And third digital moving image data, wherein the recording medium has first, second, and third recording areas, and the average recording time of the first digital moving image data is T1 seconds;
The average recording time of the second digital moving image data is T2
Second, the average recording time of the third digital moving image data is T
3 seconds, the maximum access time indicating the sum of the seek time required for the head unit to move from the innermost circumference of the recording medium to the outermost circumference and the time required for the recording medium to make one rotation, and the maximum access time S seconds, When the average bit rate of the digital moving image data is A (bps), the control unit sets the recording speed of the first digital moving image data to (T1 + T
2 + T3 + 3 * S) * A / T1 bps or more, and the recording speed of the second digital moving image data is set to (T1 + T2 + T3).
+ 3 * S) * A / T2 bps or more and the recording speed of the third digital moving image data is (T1 + T2 + T3 + 3 *)
2. The disk device according to claim 1, wherein recording control is performed at S) * A / T 3 bps or more. 14. The control unit sets the recording speed of the first digital moving image data to (T1 + T2 + T3 + 3 * S * (N +
1)) * A / T1 bp or more and the recording speed of the second digital moving image data is set to (T1 + T2 + T3 + 3 * S * (N
+1)) * A / 2 bps or more and the recording speed of the third digital moving image data is set to (TI + T2 + T3 + 3 * S *).
2. The disk device according to claim 1, wherein recording control is performed at (N + 1) * A / T3 bps or more. 15. The digital continuous data includes first and second data.
And third digital moving image data, wherein the recording medium has first, second, and third recording areas, wherein the average reproduction time of the first digital continuous data is T1 seconds, the second digital continuous The average reproduction time of the data is T2 seconds, the average reproduction time of the third digital continuous data is T3 seconds, the maximum access time indicating the time obtained by adding the time for the recording / reproduction head to make one rotation of the recording medium is S seconds, and the reproduction time is S seconds. Assuming that the average bit rate of the digital video data to be reproduced is A (bps), the control unit sets the reproduction speed of the first digital video data to (T1 + T2 + T3 + 3 * S) * A / T1
bps or more and the reproduction speed of the second digital moving image data is (T1 + T2 + T3 + 3 * S) * A / T2 bps or more, and the reproduction speed of the third digital moving image data is (T
8. The disk device according to claim 7, wherein reproduction control is performed at 1 + T2 + T3 + 3 * s) * A / T3bps or more. 16. When the maximum number of retries in case of seek failure is N, the control unit sets the reproduction speed of the first digital moving image data to (T1 + T2 + T3 + 3 * S * (N +
1)) * A / T1 bp or more and the reproduction speed of the second digital moving image data is set to (T1 + T2 + T3 + 3 * S * (N
+1)) * A / 2 bPs or more and the reproduction speed of the third digital video data is (T1 + T2 + T3 + 3 * S *
16. The disk device according to claim 15, wherein reproduction control is performed at (N + 1) * A / T3 bps or more. 17. The digital continuous data includes first and second digital data.
And third digital moving image data, the recording medium has first, second, and third recording areas, and the buffer memory temporarily stores the first and second digital moving image data, respectively. A first digital moving image data having an average reproduction time of T1 seconds, a second digital moving image data having an average reproduction time of T2 seconds, and a third digital moving image. The average reproduction time of the image data is T3 seconds, the maximum access time indicating the time obtained by adding the time for the head unit to make one rotation of the recording medium is S seconds, and the average bit rate of the input digital moving image data is A ( bps), the control means controls the reproduction by setting the sum of the first, second and third buffer memory units to (9 * S + 2T1 + 2T2 + 2T3) * A bits or more. The disk apparatus according to claim 7. 18. The digital continuous data includes M digital moving image data, and the control means controls the M digital moving image data.
When simultaneously recording digital moving image data by time division, the average recording time of the first digital moving image data is T
1 second, the average recording time of the second digital moving image data is T2 seconds, the average recording time of the third digital moving image data is T3 seconds, and the average recording time of the mth digital moving image data is Tm seconds. The maximum access time of the recording medium (the seek time required for the head unit to move from the innermost circumference to the outermost circumference of the
The time obtained by adding the rotation time) is S seconds, and the average bit rate of the input digital moving image data is A (bp).
s), the recording speed of the first digital moving image data is (T1 + T2 + T3 +... + Tm + m * S) * A /
T1 bps or more and the recording speed of the second digital moving image data is (T1 + T2 + T3 +... + Tm + m * S) * A
/ T2 bps or more and the recording speed of the third digital moving image data is (T1 + T2 + T3 +... + Tm + m * S) *
2. The disk device according to claim 1, wherein A / T is set to 3 bps or more. 19. The digital continuous data includes m pieces of digital moving image data, and the control section determines the average of the first digital moving image data when simultaneously reproducing the m moving images in time division. The reproduction time is T1 seconds, the average reproduction time of the second digital moving image data is T2 seconds, the average reproduction time of the third digital moving image data is T3 seconds, the reproduction time of the mth moving image is Tm seconds, and the recording is performed. The maximum access time of the medium (the seek time required for the head unit to move from the innermost circumference to the outermost circumference of the recording medium plus the time required for the recording medium to make one rotation) is S seconds, and the reproduction is performed. The average bit rate of digital video data is A (b
ps), the reproduction speed of the first digital moving image data is (T1 + T2 + T3 +... + Tm + m * S) * A
/ T1 bps or more and the reproduction speed of the second digital moving image data is (T1 + T2 + T3 +... + Tm + m * S) *
A / T2 bps or more and the reproduction speed of the third digital moving image data is (T1 + T2 + T3 +... + Tm + m * S)
* A / T3 bps or more, and the reproduction speed of the m-th digital moving image data is (T1 + T2 + T3 +... + Tm + m *
The disk device according to claim 7, wherein S) is set to be not less than * A / Tmbps. 20. When the maximum number of retries in case of a seek failure is N, the control means sets the reproduction speed of the first digital moving image data to (T1 + T2 + T3 + ... ten Tm + m
* S * (N + 1)) * A / T1 bps or more and the reproduction speed of the second digital moving image data is (T1 + T2 + T3
+ ... + Tm + m * S (N + 1)) * A / T2 bps or more and the reproduction speed of the third digital moving image data is (T1
+ T2 + T3 ... Tm + m * s * (N + 1)) * A / T
3 bps or more, the reproduction speed of the m-th digital moving image data is set to (T1 + T2 + T3 +... + Tm + m * S * (N +
20. The disk drive according to claim 19, wherein 1)) * A / Tmbps or more.