JP2885068B2 - Variable transfer rate data playback device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to variable transfer rate data obtained by performing high-efficiency encoding so that at least the amount of code per predetermined time for a moving image is changed according to the amount of information. The present invention relates to a variable transfer rate data reproducing apparatus from a recording medium recorded using a highest transfer rate in a change range of a transfer rate.

[0002]

2. Description of the Related Art For example, linear quantization in which a signal level is equally divided for each sample value of a digital image signal and a value included in each range is replaced with one representative value.
In order to prevent the difference between the representative point and the original value when using the (equal quantization) means, it is generally necessary to use 6 bits (64 gradations) to 8 bits (256 gradations) for a natural image. )
Therefore, if an image signal digitized by equal quantization is recorded, reproduced, transmitted, etc. as it is, it is necessary to handle such a large amount of information for each sample value. Will be required. Therefore, it is well known that various high-efficiency coding methods have been conventionally proposed in order to record, reproduce, and transmit an image signal to be recorded, reproduced, and transmitted with a smaller amount of information. It is as follows.

That is, when encoding an image signal with a small amount of information, for example, a change in a portion where a signal changes little is sensitive, but a certain error may occur in a portion where a signal changes rapidly. The image is decomposed into pixels using the correlation on the spatio-temporal axis of the information signal to be recorded, utilizing the characteristics of human vision and hearing that are difficult to detect Intra-frame predictive coded image by time axis prediction mode, transmitting a small number of approximate values of original information using the height of adjacent correlation of luminance value, or transmitting inter-pixel difference or inter-frame difference , Predictive coding of inter-frame predictive coded images, and reduction of frequency components by utilizing the fact that there are few high frequency components. After recording, transmitting and transmitting the digital image / data whose data amount has been compressed, and reproducing / receiving the digital image / data whose data amount has been compressed as described above, the image data is transmitted. 2. Description of the Related Art Decompression of an image by expanding the data has been conventionally performed.

On the other hand, with respect to recording media used for recording and reproducing various types of information, recently, as the demand for recording various types of information signals at a high recording density has increased, various media based on various constitutional principles and operating principles have recently been developed. The created information recording medium enables high-density recording and reproduction of information signals. For example, magnetic recording according to the information signal is performed on a recording layer made of a ferromagnetic material in the information recording medium, or magneto-optical recording is performed. The recording / reproduction is performed by optical means using a recording medium, or, for example, the information signal is recorded by forming irregularities corresponding to the information signal on the signal surface of the information recording medium, and the recorded information is recorded. Reproduction of signals by optical means has already been put to practical use, and in order to meet the demands for high-density recording and reproduction in various technical fields, information recording media have been developed. The recording layer of the information recording medium is irradiated with a beam intensity-modulated by the information signal to cause a physical change or a chemical change in the recording layer of the information recording medium in accordance with the information signal, thereby recording the information signal. The information recording medium described above has also been put to practical use.

[0005] As a semiconductor laser capable of performing a stable operation can be easily obtained, various types of optical recording media for performing high-density recording and reproduction using a laser beam have been developed in a non-contact state. Recording and playback is possible,
In order to have the advantage of being resistant to scratches and dust and obtaining a large storage capacity by high-density recording, a large amount of information signals are recorded from the master on which information signals are recorded by pits formed as geometric concave or convex parts. For example, a compact disc (CD) has been widely used as a copied recorded optical disc (playback-only optical disc), and a CD-I (Co)
Also, as a rewritable optical disk, for example, a magneto-optical disk or another optical disk is used in office file memory or other applications (for example, an MD using a magneto-optical disk). ) Has been.

By the way, for example, in the above-mentioned compact disc (CD), an audio signal is digitally encoded such that a code amount generated per unit time with respect to an original signal is constant regardless of information content. Is a recorded recording medium that has been recorded on the recording medium at a constant transfer rate, even when reproducing the recording data from the recording medium, only by reproducing at the same constant transfer rate as the above-mentioned recording,
Since the data amount per unit time is reproduced in a constant state, a reproduced signal can be easily obtained by decoding the data amount. A special configuration or the like is required for the recording system, the recording medium, and the reproducing system. No need to apply.

On a CD-I disk, for example, an acoustic signal whose information amount is compressed by adaptive pulse code modulation (ADPCM) is recorded on a recording medium at a fixed transfer rate determined by a sampling period. For example, in the above-mentioned MD (mini-disc), the amount of information is compressed and recorded on a recording medium at a constant transfer rate.
The reproduction data obtained by reproducing the recording data recorded on these recording media is the reproduction data amount per predetermined time, and the processing data amount per predetermined time in the decoder is constant. Sometimes it is not necessary to perform complicated control or the like. This point will be described more specifically with reference to FIGS. 7 and 8 as follows.

FIG. 7 is a diagram showing read (reproduced) reproduction of recorded data from a recording medium 1 on which recording data in a compressed state of information is recorded, such as a CD-I disk or a mini-disc described above. FIG. 7 is a block diagram showing a schematic configuration of an example of a reproducing apparatus configured to be able to obtain a reproduced signal by performing signal processing on the reproduced data after obtaining data. This is a signal reproducing unit including a signal processing unit, and the signal reproducing unit 48 shown in FIG. 7 is shown as using an optical reproducing element. 49 is a data storage unit,
52 is a decoding unit, 51 is a reproduction control unit, and 53 is a reproduction signal output terminal. FIG. 8A shows that the data amount of the original signal to be recorded is always constant on the time axis, and FIG. FIG. 8A illustrates a case where compressed data in which the data amount of the original signal shown in FIG. 8A is uniformly compressed (in the illustrated example, reduced to 1/4) is recorded as recording data on the recording medium 1. ing.

A recording medium 1 (shown as an optical disk in the following description, which is described as an optical disk 1) shown in FIG. 7 is rotated at a predetermined rotational speed by a rotation driving device (not shown). And a reproducing element (optical head) provided in the signal reproducing unit 48 includes a focus control system (not shown),
Under the control of an automatic control system such as a tracking control system, a reproduction operation (read operation) of recorded data from an optical disc is performed. The reflected light of the spot of the laser light emitted from the optical head formed on the signal surface of the optical disk 1 is converted into an electric signal by a photodetector in the optical head, and is provided in a signal reproducing unit 48. The signal processing section performs predetermined signal processing to accumulate data as reproduction data.

By the way, as illustrated in FIG. 8A, an original signal having a constant data amount on the time axis is uniformly compressed at a constant compression ratio (in the illustrated example, it is reduced to 1/4). compression)
The recorded data in the recorded state, that is, the recorded data on the optical disk 1 on which the recorded data as illustrated in FIG. 8B is recorded (reproduced), and a predetermined signal processing is performed to perform a reproduction signal. In the case where the recording data recorded on the optical disc 1 is continuously reproduced as reproduction data by the operation of the signal reproducing unit 48 and supplied to the decoding unit 52, As a result, reproduced data having a data amount four times as large as the reproduced data per unit time required for decoding the reproduced signal by the decoding unit 52 is supplied to the decoding unit 52.

As shown in FIG. 8C, in order to supply reproduced data of a data amount not exceeding the decoding capability of the decoding unit 52 to the decoding unit 52, as shown in FIG. During the reproduction period (the period indicated as reproduction in (c) of FIG. 8) set to read the record data from the optical disc 1, the record data recorded in the record data is recorded at the highest read rate. Is reproduced so that reproduction data can be obtained. During periods other than the reproduction period described above, an intermittent operation such as performing a standby without performing a reproducing operation (a period indicated as standby in FIG. 8C) is performed. In order to cause the signal reproducing section 48 to perform a proper reproducing operation and to output a good reproduced signal from the reproducing apparatus, it is possible to supply reproduced data of a data amount necessary for decoding to the decoding section 52 without excess or deficiency. .

As described above, as means for causing the signal reproducing section 48 to perform an intermittent reproducing operation, for example, the optical disk 1 is rotated at a predetermined rotational speed only when reading recorded data from the optical disk 1, Although there is no conceivable means for stopping the optical disk 1 during standby, the optical disk and its rotating drive part are mechanical components, and therefore, the playback period and the standby period within a short time are reduced. It is very difficult to configure such that the switching operation can be performed well. Therefore, as means for causing the signal reproducing unit 48 to perform an intermittent reproducing operation, the optical disc 1 is reproduced by the signal reproducing unit 48 during the above-mentioned reproducing period.
In the memory of the data storage unit 49, the reproduced data read from the optical disc 1 is written into the memory of the data storage unit 49 during the standby period. Is stopped, and the reproducing element of the signal reproducing unit 48 is set to one of the optical discs 1 so that the reproducing element of the signal reproducing unit 48 repeatedly tracks the same recording trace (track) on the optical disc 1. A track jump of one recording trace is performed every rotation.

During the reproduction period during the intermittent reproduction operation of the signal reproduction section 48, compressed data having the data amount shown in FIG.
Data amount of the reproduction data in the memory in the data storage unit 49 written as the reproduction data {see FIG. 8D}.
Is the same as the data amount shown in FIG. From the memory of the data accumulating unit 49, reproduced data of a data amount per unit time such that a decoding operation is performed in a state where the reproduced signal is continuously transmitted to the output terminal 53 from the decoding unit 52 is read out and decoded. A reproduction signal as shown in FIG. 8E, which is supplied to the decoding unit 52 and sequentially decoded by the decoding unit 52, is sent to an output terminal 53.

In the conventional reproducing apparatus described with reference to FIGS. 7 and 8, data to be recorded / reproduced is always constant on a time axis as illustrated in FIG. 8A. Since the original signal having the data amount of is uniformly compressed (compressed to で は in the illustrated example) at a fixed compression rate and has a fixed fixed transfer rate, The data amount per unit time of the reproduction data intermittently reproduced from the optical disc 1 by the reproduction unit 48 is equal to the reproduction data amount per unit time decoded by the decoding unit 52.
In the normal playback state, the data amount does not locally change and the playback data amount per unit time read from the data storage unit 49 and supplied to the decoding unit 52 is constant. The control of the intermittent reproduction operation in the signal reproduction unit 48 by the unit 51 only needs to repeat the continuous reproduction operation and the standby operation every predetermined time.

[0015]

As described above, the original signal is digitally encoded such that the amount of code generated per unit time with respect to the original signal is constant regardless of the information content. In a conventional general recording / reproducing apparatus in which recording is performed on a recording medium at a fixed and constant transfer rate, and recording data is reproduced from the recording medium at the same transfer rate as when recording, data per unit time is used. Since the amount is always constant, there is an advantage that there is no need to apply a special configuration or the like to the recording system, recording medium, and reproduction system.However, the information content in the original signal is fixed and fixed. Because recording and playback are performed at the transfer rate,
It has been impossible to record and reproduce information of the original signal for a long time so as to effectively utilize the recording capacity of the recording medium.

In the information content of the original signal, a small code amount is assigned as a code amount per predetermined time to a portion of the information content which does not affect the restoration. For a portion of the information content that is highly necessary at the time, a large amount of code is allocated as the amount of code per predetermined time, and a variable transfer rate coding that effectively utilizes the recording capacity of the recording medium. An efficiency coding scheme has been proposed. Then, when the recording data obtained by high-efficiency encoding by the high-efficiency encoding method by the variable transfer rate encoding is recorded at a predetermined recording density on a recording medium having a predetermined storage capacity, As compared with the case where the recording data obtained by performing the high-efficiency encoding by the conventional high-efficiency encoding method by the conventional fixed transfer rate encoding is recorded at the same recording density as that described above, the time length is twice as long. And the recording data corresponding to the original signal could be recorded.

However, a decoding unit which decodes the coded data obtained by implementing the above-mentioned proposed high efficiency coding scheme using the variable transfer rate coding and outputs a reproduced signal outputs a good reproduced signal. Since the data amount of the reproduced data per unit time that can be changed greatly changes on the time axis as illustrated in, for example, FIG. As in the conventional reproducing apparatus described with reference to FIG. 8, the signal reproducing section performs an intermittent reproducing operation at predetermined time intervals, and reproduces the reproduced data read from the signal reproducing section during the reproduction period. When the data is stored in the memory of the storage unit, and the data storage unit supplies the decoding unit with a predetermined amount of reproduction data at predetermined time intervals, the reproduction signal cannot be decoded. It occurs that continuous image signal can not be restored.

In the decoding unit to which the coded data obtained by implementing the highly efficient coding scheme based on the previously proposed variable transfer rate coding as described above is supplied, a predetermined value required for decoding is provided. The data amount of the reproduced data per unit time greatly changes on the time axis as illustrated in FIG. 5A, for example. Even if the CPU provided in the control unit of the reproducing apparatus is conventionally required to perform a control operation for supplying reproduced data having a small data amount to the decoding unit, the processing capability of the CPU does not allow a normal operation. In addition to the reproduction control, it is not possible to perform even the above-described extra control operation. Therefore, the data storage unit always supplies the decoding unit with reproduction data of a sufficient data amount to the decoding unit. Dedicated CPU and that can perform the control operation and the regeneration control operation, when it is added to other hardware, such as the point to large-scale and cost of the playback device becomes a problem.

In the conventional reproducing apparatus, the reproducing element of the signal reproducing unit repeatedly tracks the same recording trace (track) of the optical disk during the standby period in the reproducing operation as described above. Thus, the read element of the signal reproducing unit is caused to perform a track jump of one recording trace every rotation of the optical disk so as to prepare for the start of reading of the next recording data. When the ratio between the amount of data read from the optical disc by the unit and the amount of data processed by the decoding unit is large, the length of the standby period is longer than the length of the playback period of the data recorded from the optical disk by the signal reproducing unit. Becomes longer, so that the number of times of performing one-track reproduction increases.

The above point will be described below with reference to FIG. The spiral line in FIG. 6A is a recording trace of the optical disc, and the thick arrow line in the section from point A to point B in FIG. This is one track that has been read. The portion of the recording trace indicated by the dotted line from point B to point C is the recording trace that the light spot of the reproducing element tracks during the standby period, and the light trace by the reproducing element during the standby period. The spot is, for example, point B → recorded mark with dotted line → point C → point D → recorded mark with dotted line → point C →
The light spot by the reproducing element during the standby period during which the recording trace is traced as indicated by the dot b →... Is, for example, a bold line from which the recorded data is read during the immediately preceding reproduction period. The recording trace of → b →→ a →→ the recording trace indicated by the bold line from which the recording data was read during the immediately preceding reproduction period → b → b → a →→ Then, the reproducing element of the signal reproducing unit rotates by one recording track every rotation of the optical disk so that the reproducing element of the signal reproducing unit repeatedly tracks the same recording trace (track) of the optical disk. The track jump will be repeated for minutes. The track jump is performed by supplying a kickback pulse to an actuator provided in the tracking control system.

Therefore, as described above, when the compression ratio of the recording data with respect to the original signal increases and the ratio of the length of the standby period to the length of the reproduction period increases, the number of kickbacks inevitably increases. As the number of times the actuator is forcibly driven and controlled increases, the stress applied to the support mechanism and the drive coil of the actuator increases, so that shortening their life becomes a problem. . When a kickback pulse is applied to the actuator of the tracking control system as described above and the reproducing element is displaced, a circuit of the tracking control system is naturally cut off, and thus the tracking control system is disconnected. Since the system becomes uncontrollable, the operation during the period until the tracking control system becomes stable becomes extremely unstable.

When the read element is displaced by the application of a kickback pulse to the actuator of the tracking control system, if that portion is a defect of the optical disk, a large track jump occurs. By the way, when shifting from the standby period to the reproduction period, it is necessary to move to a predetermined track to be reproduced next, but if a track jump occurs as described above, the next reproduction is performed. In order to search for a given track that is targeted for and move to that track, it will be cumbersome to move between many tracks,
A long time may be required before the reproduction operation is restarted. When the time until the resuming operation is long as described above, a memory having a large storage capacity is required as a memory to be provided in the data storage unit, and the time until the resuming of the regenerating operation is expected. If the length is extremely longer than that, the reproduced data to be supplied from the data storage unit to the decoding unit may be interrupted and the reproduced signal may not be output. As described above, the conventional reproducing apparatus has many problems to be solved.

[0023]

According to the present invention, variable transfer rate data obtained by performing high-efficiency coding so that at least the amount of code per predetermined time for a moving image is changed according to the amount of information is recorded as record data. What is claimed is: 1. A variable transfer rate data reproducing apparatus for recording data from a recording medium recorded using a highest transfer rate in a range of a change in the transfer rate, wherein a reproducing element and a signal processing unit driven and displaced by at least an actuator of a tracking control system A signal reproduction unit configured to include, a data storage unit that stores reproduction data reproduced by the signal reproduction unit, a decoding unit that decodes reproduction data supplied from the data storage unit, A reproduction control unit for controlling operations of the signal reproduction unit, the data storage unit, and the decoding unit; A data control signal for supplying from the memory of the data storage unit to the decoding unit a reproduced data having a data amount such that a decoding operation on the variable transfer rate data in the decoding unit can be performed in a state in which the decoding unit outputs the data control signal. The amount of the reproduced data stored in the memory of the data storage unit, which is changed by reading the reproduced data supplied from the memory of the data storage unit to the decoding unit, is changed by the means provided to the data storage unit and the data control signal. The reproduction operation performed intermittently so as not to greatly exceed the storage amount between the predetermined maximum storage amount and the predetermined minimum storage amount is performed from the recording medium. The playback control from the data storage unit is performed so that the content of the recorded data to be performed by the signal playback unit is properly aligned in a predetermined order. Means for controlling the operation of the signal reproducing unit by the reproduction control unit based on the reproduction control signal given to the unit, and controlling the intermittent reproduction operation in the signal reproducing unit by the reproduction control unit based on the reproduction control signal. Means for performing such an operation that the reproducing element is continuously tracked to the recording trace by the operation of the tracking control system during the period of interruption of the reproducing operation, and the reproduction control signal described above. In the case where the reproduction control unit controls the intermittent reproduction operation in the signal reproduction unit based on the above, when the reproduction operation which has been interrupted is resumed, the reproduction position element immediately before the time when the reproduction operation was interrupted is Means for sequentially supplying a plurality of kick pulses to an actuator of a tracking control system so that the reproducing element is driven and displaced to the position, Variable means comprising means for controlling a write operation by a write control signal given from the playback control unit to the data storage unit, and means for controlling a decoding operation in the decoding unit by a decode control signal given from the playback control unit to the decoding unit. Provided is a transfer rate data reproducing apparatus.

[0024]

The variable transfer rate data obtained by performing high-efficiency coding to change the code amount per predetermined time for a moving image according to the information amount is the highest in the transfer rate change range described above as the recording data. The recording medium on which recording is performed using the transfer rate is driven and rotated under the control of the rotation control system so as to have a predetermined rotation speed. The reproducing element provided in the signal reproducing section is driven and displaced by the actuator of the tracking control system. An operation for continuous tracking is performed. Further, upon resuming the suspended reproducing operation, the reproducing element is driven and displaced to the position of the reproducing position element immediately before the reproduction operation is suspended. The recording data read from the recording medium during the reproducing period by the reproducing element in the signal reproducing section is subjected to signal processing and stored in the memory of the data storage section as reproduced data.
The reproduction data stored in the data storage unit is supplied to the decoding unit by a data control signal provided from the decoding unit to the data storage unit, and the decoding unit performs a decoding operation on the variable transfer rate data so that the reproduction signal is output without interruption. Do.

When the reproduced data supplied from the memory of the data storage unit to the decoding unit is read by the data control signal, the amount of reproduced data stored in the memory of the data storage unit changes. Data storage unit so that the storage amount of the reproduction data in the memory of the unit does not greatly exceed the storage amount between the predetermined maximum storage amount and the predetermined minimum storage amount. The playback control unit controls the signal playback unit to perform the playback operation intermittently based on the playback control signal generated in step (1). Further, the reproduction control unit may be configured such that the content of the recording data read out from the recording medium intermittently performed in the signal reproduction unit is performed by the signal reproduction unit in a state where the contents are correctly aligned in a predetermined order.
In addition to controlling the operation of the signal reproducing unit, the writing operation of the memory in the data storage unit is controlled, and the decoding operation in the decoding unit is controlled by a decoding control signal given from the reproduction control unit to the decoding unit.

[0026]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The specific contents of the variable transfer rate data reproducing apparatus of the present invention will be described below in detail with reference to the accompanying drawings. FIG. 1 is a block diagram showing a schematic configuration of a variable transfer rate data reproducing apparatus according to the present invention. FIG. 2 is a block diagram showing a specific configuration example of a data storage unit.
8 is a diagram for explaining the operation of the reproducing device, FIG. 6 is a diagram for explaining the state of displacement of the reproducing element during a reproducing period and a waiting period, and FIG. 7 is a conventional fixed transfer rate data reproducing device. FIG. 3 is a block diagram illustrating a configuration example of FIG. In FIG. 1 showing an example of the configuration of the variable transfer rate data reproducing apparatus of the present invention, reference numeral 1 denotes a recording medium, 50 denotes a signal reproducing unit, 21 denotes a data storage unit, 22 denotes a reproduction control unit, and 26 denotes a decoding unit. The recording medium 1 is rotated by a drive motor 2 that is driven and rotated at a predetermined rotation speed and rotation phase under rotation control by a rotation control system 12.

On the recording medium 1 described above, encoded data (variable transfer rate data) obtained by performing high-efficiency encoding by a high-efficiency encoding method using variable transfer rate encoding is recorded as recording data. The high-efficiency coding method using the variable transfer rate coding described above allocates a small code amount as a code amount per predetermined time to a portion of the information content of the original signal that does not affect the restoration. Of the information content of the signal, for the information content portion having a large information amount, a large code amount is allocated as the code amount per predetermined time so that the recording capacity of the recording medium is effectively utilized. The amount of recording data per unit time of the variable transfer rate data which is a high-efficiency coding method and which is highly-efficiently coded by the above-mentioned high-efficiency coding method by the variable transfer rate coding is, for example, as shown in FIG. a)
As illustrated in FIG.

On the recording medium 1 on which the recording data of the variable transfer rate data is recorded as described above, the recording data obtained by performing the high-efficiency encoding by the conventional high-efficiency encoding method by the fixed transfer rate encoding is the same. As compared with the case where the recording is performed at the recording density of, the original signal having the double time length and the recording data corresponding thereto can also be recorded. Then, the aforementioned recording medium 1
For example, an optical disk, a magneto-optical disk, a magnetic disk, or a recording medium having any other configuration may be used. FIG. 1 shows a case where the recording medium 1 is an optical disk. In the following description, the recording medium 1 may be described as an optical disk.

In the variable transfer rate data reproducing apparatus according to the present invention, reproduced data obtained by signal processing of the recorded data based on the variable transfer rate data reproduced (read) from the recording medium 1 by the signal reproducing section 50 is stored in the data storage section. The decoding signal is supplied to the decoding unit 26 via the decoding unit 21 to obtain a reproduced signal by the decoding operation in the decoding unit 26. However, the reproduced signal is obtained by the high efficiency coding method using the variable transfer rate coding. In the decoding unit 26 that decodes the reproduced data based on the variable transfer rate data and outputs the reproduced signal, the data amount of the reproduced data per predetermined unit time at which a good reproduced signal can be output is, for example, as shown in FIG. As shown in (a), it changes greatly on the time axis.

The amount of data per unit time of variable transfer rate data obtained by performing high efficiency coding of moving picture information by the above described high efficiency coding scheme using variable transfer rate coding is, for example, shown in FIG. (A), the data amount greatly changes in a change mode as illustrated in (a). The change in the data amount described above occurs for each image unit (frame unit) and a plurality of image units Also occurs for each group of image units (image unit set). In the example shown in FIG. 5A, it is assumed that the above-mentioned image unit group constitutes a group of image units by six image units, and each image unit group is divided by a vertical dotted line in the figure. Is shown. In an example of an actual moving image, the image unit group described above often includes 15 to 30 frames.

That is, when the variable transfer rate data obtained by performing the high-efficiency coding on the actual moving image by the high-efficiency coding method using the variable transfer rate coding was examined, the data amount per image unit (every short time) was examined. It is recognized that there is a change and a change in the data amount for each image unit group (every relatively long time). The change in the data amount for each image unit is, for example, a change in the data amount for each frame. As the image unit, for example, MPEG
(Moving Picture Image Codin
The following describes an example of an encoding method (MPEG method) of moving image information for a recording medium for recording digital data in (g Expert Group).

In the MPEG system, an image unit {I} in which image data is compressed by applying an intra-frame prediction method
Picture (Intra Pictures)-> I
Also referred to as a frame {} and an image unit in which image data is compressed by applying an inter-frame prediction method in which inter-frame prediction is performed based on image data of a past frame {P picture (Predicated)
Pictures) → hereinafter also referred to as a P frame, and an inter-frame prediction method for performing inter-frame prediction based on both image data of a past frame and image data of a future frame. An image unit in which image data is compressed by applying the B-picture (Bi-directional Pred
(Picture Pictures) → Hereinafter, image units (frames) are defined in three types of image modes, which are sometimes referred to as B frames.

In the MPEG system, the relationship between the compression ratio of the image data in the I frame, the compression ratio of the image data in the P frame, and the compression ratio of the image data in the B frame is expressed by the following equation. (Compression rate) <(compression rate of image data in P frame) <(compression rate of image data in B frame)
In general, the data amount in the I frame is twice to ten times the data amount in the P and B frames. Further, the data amount of each of the image unit groups composed of one type of frame or a combination of a plurality of types of frames in the above-described I, P, and B frames is mainly in the case of a scene change (switching of scenes) or a scene of fast-moving scenes. In such a case, the data amount becomes large.

As described above, the recording data of the variable transfer rate data obtained by performing the high-efficiency coding by the high-efficiency coding method using the variable transfer rate coding has a data amount per predetermined unit time, for example, as shown in FIG. As shown in FIG. 5 (a), the data is largely changed on the time axis, so that the reproduction of the recording data from the recording medium 1 is performed by the decoding unit 26 for the reproduction required for the decoding. It is necessary that the reproduced data can be supplied to the decoding unit 26 in a state where the data amount of the data does not become excessive or insufficient. Therefore, in the variable transfer rate data reproducing apparatus of the present invention, the signal reproducing unit 50 performs the intermittent reproducing operation while causing the reproducing element 3 to perform the seek operation, that is, during the period when the reproducing operation is interrupted (standby period). Reproducing element 3 in
Operates so as to continuously track the recording trace by the operation of the tracking control system. Then, the reproducing element 3 is driven to be displaced to the position shown in FIG. 3, and the reproducing element in the signal reproducing section 50 reproduces the recording data from the recording medium 1 during the reproducing period.

The recording data reproduced from the recording medium 1 is
The signal processing unit 14 in the signal reproducing unit 50 performs predetermined signal processing, and stores the data as reproduced data in the memory 46 of the data storage unit 21 (FIG. 2). And
The reproduction data stored in the memory 46 of the data storage unit 21 is read out from the memory 46 and supplied to the decoding unit 26 when a data control signal is given from the decoding unit 26 to the data storage unit 21. . As described above, the data storage unit 2
The data amount of the reproduced data read from the memory 46 and supplied to the decoding unit 26 is determined by the data control signal supplied from the decoding unit 26 to the data storage unit 21 as described above.
Control is performed so that the amount of data is sufficient for the decoding operation in the decoding unit 26.

The memory 4 of the data storage unit 21
The storage amount of the reproduction data in 6 greatly exceeds the storage amount between a predetermined maximum storage amount and a predetermined minimum storage amount by a control operation for each component described later. To avoid such a situation,
For example, when the storage amount of the reproduction data in the memory 46 of the data storage unit 21 becomes equal to or smaller than a predetermined storage amount, the reproduction control unit 22 generates the reproduction control signal based on the reproduction control signal generated by the data storage unit 21. The reproduction operation in the signal reproduction unit 50 is preferentially performed by the control signal. Further, the reproduction control unit 22 is configured so that the content of the recording data read out from the recording medium 1 intermittently performed in the signal reproduction unit 50 is performed by the signal reproduction unit in a state where the contents are correctly aligned in a predetermined order. The operation of the signal reproducing unit 50 is controlled and the data storage unit 21 is controlled.
And the decoding operation in the decoding unit 26 is controlled by a decoding control signal given from the reproduction control unit 22 to the decoding unit 26.

In the signal reproducing section 50, reference numeral 3 denotes a reproducing element (optical pickup), and a laser light source (semiconductor laser) 4
Is collimated by the collimator lens 55 in the optical member 5 and then passes through the polarizing beam splitter 56 and the quarter-wave plate 57 before being incident on the objective lens 6 to be irradiated with the laser light. Light is objective lens 6
Thus, an image is formed on the signal surface of the optical disk 1 as a light spot having a small diameter. The reflected light from the light spot enters the polarization beam splitter 56 via the objective lens 6 and the 波長 wavelength plate 57, is reflected by the polarization beam splitter 56, and is then detected by the cylindrical lens 58. Incident on the vessel 8. As the photodetector, for example, a quadrant photodetector may be used. From the photodetector 8, an electric signal corresponding to recording data reproduced from the optical disc 1, an electric signal including a focus error signal, a tracking error signal, and the like are output.
Is supplied to the operational amplifier 15.

In the operational amplifier 15, the photodetector 8
Of the electric signal supplied from the optical disk 1 to generate an electric signal including recording data reproduced from the optical disc 1, a focus error signal, and a tracking error signal. An electric signal including recording data reproduced from the optical disk 1 is supplied to a synchronization detection / demodulation circuit 16 and a phase locked loop (PLL) 17, and a focus error signal is supplied to a focus servo system in an optical pickup control system. The tracking error signal is supplied to a tracking servo system 10 and a coarse motor system 11 in the optical pickup control system. The above-described focus servo system 9 and tracking servo system 10
A control signal is also supplied to the coarse motor system 11 and the rotation control system 12 from a reproduction control circuit 23 in the reproduction control unit 22.

The objective lens 6 provided in the optical pickup 3 moved in the radial direction of the optical disk 1 by the coarse motor 13 driven by the output signal from the coarse motor system 11 is supplied from the focus servo system 9. The direction of the optical axis of the objective lens 6 and the optical disk 1 are controlled by the actuator 7 to which the focus control signal supplied from the controller 7 and the tracking control signal supplied from the tracking servo system 10 are supplied.
The optical pickup 3 is driven and displaced in the radial direction by the automatic position control operation by the automatic control systems described above.
A good reproduction operation can always be performed. In addition, a seek operation described later is also performed favorably by the operations of the coarse motor system and the tracking servo system.

In the phase locked loop 17 of the signal processing section 14, a clock signal for data reproduction is extracted, and the extracted clock signal is supplied to the synchronization detection / demodulation circuit 16. The synchronization detection / demodulation circuit 16 detects a synchronization signal, and demodulates subcode data and main code data based on the synchronization signal. The subcode data including the reproduction position information of the recording medium is sent to the subcode reader 20, and the output signal from the subcode reader 20 is supplied to the reproduction control circuit 23 of the reproduction control unit 22. The main data demodulated by the synchronization detection demodulation circuit 16 and supplied to the error correction deinterleave circuit 18 is stored in a random access memory 19 and then transmitted to the error correction deinterleave circuit 18 and the random access memory 19. Reproduced data that has been subjected to error correction by a known error correction signal processing operation performed while data is exchanged between the two circuits is supplied to the data storage unit 21.

By the way, as described above, in the variable transfer rate data reproducing apparatus of the present invention, the data amount per predetermined unit time is greatly reduced on the time axis as exemplified in FIG. The reproduction data obtained by reproducing the recording data with the variable transfer rate data in the state of changing from the recording medium 1 and performing signal processing is used as reproduction data of a data amount required for decoding in the decoding unit 26. Are supplied to the decoding unit 26 in a state where no excess or shortage occurs, and the decoding unit 2
6, a good reproduction signal must be output via the output terminal 42. However, the reproduction data handled by the variable transfer rate data reproducing apparatus of the present invention is not the fixed transfer rate reproduction data but the variable transfer rate data. Therefore, in order to ensure that the reproduced data obtained by performing signal processing on the recorded data reproduced from the recording medium 1 is always smoothly supplied to the decoding unit 26 with an appropriate amount of data without excess or deficiency, the reproducing apparatus It is necessary that the operation of each component of the reproducing apparatus be controlled in relation to each other so that the data amount of the reproduction data is appropriate in each component.

Therefore, in the variable transfer rate data reproducing apparatus of the present invention, the signal reproducing section 50, the data storage section 21,
By controlling the operations of the decoding unit 26 and the like in a related manner by the reproduction control unit 22, the reproduction data obtained in correspondence with the recording data reproduced from the recording medium 1 is always decoded with an appropriate amount of data without excess or deficiency. It is supplied to the section 26 smoothly. In the control operation of the reproduction control unit 22 performed on the signal reproduction unit 50, the data storage unit 21, the decoding unit 26, and the like in the variable transfer rate data reproduction device,
The signal reproducing unit 50 controls the data amount of the reproduced data.
The following is a description of the control operation performed on the.

In the reproduction control unit 22, the data of the reproduction data stored (stored) in the memory 46 (see FIG. 2) provided in the data storage unit 21, which will be specifically described later with reference to FIG. Based on information indicating how much the data amount satisfies the preset data amount (hereinafter, referred to as “information about the memory sufficiency” or “sufficiency”) And generates a control signal corresponding to the reproduction control signal generated by the data storage unit 21.
The intermittent reproduction operation by the optical pickup 3 (reproduction element 3) in the signal reproduction unit 50 is controlled by the signal. That is, in the variable transfer rate data reproducing device of the present invention, the period when the reproducing operation is interrupted (the standby period)
The optical pickup 3 in the middle shows a spiral recording trace formed by a thin solid line shown in FIG.
An operation is performed in which recording traces indicated by adding dotted lines in the diagram of FIG. 6B are continuously tracked one after another by the operation of the tracking control system.

When the reproduction operation is interrupted (standby period) and the reproduction operation by the optical pickup 3 is restarted, the reproduction is performed by the optical pickup 3 immediately before the reproduction operation is stopped. An operation of driving and displacing the optical pickup 3 to a position where the recording data to be reproduced following the recording data to be reproduced can be reproduced is performed by a tracking servo in an optical pickup control system provided in the signal reproducing unit 50. The seek operation can be performed by the optical pickup 3 by one or both of the operation of the system (for example, the operation of changing the tracking track by a kick pulse or a kickback pulse) and the operation of the coarse motor system. Control signals from the playback control circuit 23 of the playback control unit 22 to the position control systems in the signal playback unit 50. Give to a given thing. In order to cause the optical pickup 3 to perform the above-described seek operation, when the reproduction control circuit 23 generates a control signal to be given to the position control system of the signal reproducing unit 50, the reproduction operation is interrupted. Optical pickup 3 to be restarted
As the information on the upper position, the subcode data supplied from the subcode reader 20 to the reproduction control circuit 23 can be used.

As described above with reference to FIG.
The light spot by the reproducing element during the period of interruption of the reproducing operation (standby period) in the conventional reproducing apparatus is generated every one rotation of the optical disk even if the recording trace on the optical disk is formed in a spiral shape. In the variable transfer rate data reproducing apparatus of the present invention, the light spot by the optical pickup 3 during the period when the reproduction operation is interrupted (standby period) is repeated. As shown in FIG. 6B, no track jump operation is performed during the period of the reproduction operation interruption (standby period), and the optical pickup 3 during the above period is The optical pickup 3 is subjected to tracking control by a tracking control system so that a light spot accurately traces a spirally formed recording trace on the optical disc 1. And is're.

A spiral line shown by a thin solid line in FIG. 6B is a recording trace, and a thick solid line from point A to point B in the above-mentioned recording trace indicates a line during the immediately preceding reproduction operation. One track where recorded data is reproduced, and a portion of a recording trace indicated by adding a dotted line to a thin solid line is, as described above, during the period when the reproducing operation is interrupted (standby period), the optical pickup 3 This shows a state in which the light spot accurately tracks the spirally formed recording trace on the optical disc 1 under the tracking control by the tracking control system. FIG.
The signs of c, d, e, f, etc. shown in (b) of
This is an example of a point where a period during which the reproduction operation is interrupted (standby period) ends and the light spot starts a seek operation. That is, in the variable transfer rate data reproducing apparatus of the present invention, the light spot by the optical pickup 3 during the period of the reproduction operation interruption (standby period) is equal to the length of the period of the reproduction operation interruption (standby period). The point at which the light spot starts the seek operation changes as shown in FIG.

In the variable transfer rate data reproducing apparatus of the present invention, the light spot by the optical pickup 3 during the period of interruption (standby period) of the reproducing operation is caused to track jump once during the period of standby of the reproducing operation. No operation is performed, and during the above-mentioned period, the light spot continuously traces the spiral recording trace on the optical disc 1, and the period when the reproduction operation is interrupted ( When the reproduction operation by the optical pickup 3 is resumed after the standby period), the recording data to be reproduced following the recording data reproduced by the optical pickup 3 immediately before the time when the reproduction operation was interrupted should be reproduced. The optical pickup 3 is driven and displaced so that the position of the light spot is located at a position where the recorded data can be reproduced. In other words, by causing the light spot of the reproducing element to repeat the one-track jump operation for each rotation of the optical disk during the standby period of the reproducing operation, the life of the actuator is shortened, and the control of the tracking control system becomes impossible. Frequent occurrence of a state does not occur in the variable transfer rate data reproducing apparatus of the present invention.

In the variable transfer rate data reproducing apparatus according to the present invention, the displacement of the optical pickup 3 when the reproduction operation by the optical pickup 3 is restarted after the interruption period (standby period) of the reproduction operation is completed. It was thought that since the volume would be larger than that of the conventional reproducing apparatus, it would take a long time for this to occur, but it was revealed that there was no such concern at all.
That is, as compared with the time value required for displacing the light spot by one recording mark interval, the time value required for displacing a number of recording mark intervals slightly increases, Since there is no difference between the above and the comparatively long time required for confirming the address for accurately determining the reading position of the recording data at the time of resuming the reproduction operation or the waiting time, the difference between the two is not recognized. From the viewpoint of the above, the time difference between the two was not so significant.

In the reproduction control unit 22, when the reproduction control circuit 23 generates a control signal to be given to the position control system of the signal reproduction unit 50, the reproduction operation in the signal reproduction unit 50 is interrupted and restarted. Power pick-up 3
The sub-code data supplied from the sub-code reader 20 to the reproduction control circuit 23 is used as the information of the upper position. Further, the reproduction control unit 22 causes the display unit 25 to display the reproduction time based on the subcode data. The reproduction control unit 22 is configured to include, for example, a microprocessor, a random access memory, a read-only memory, and the like, and is provided with an input unit provided in the operation unit 24, such as a numeric keypad, and other keys.
When the operation mode of the playback device is set, the operation mode of each component of the playback device is set, and when various other types of input information are given, a predetermined control signal is sent to each of the components related to the playback device. To control the operation of each component described above.

As described above, the reproduction control unit 22 generates a control signal for controlling the reproduction state of the signal reproduction unit 50 based on the reproduction control signal generated by the data storage unit 21.
By supplying it to the signal reproducing unit 50, the reproducing operation of the signal reproducing unit 50 is controlled. As the data storage unit 21, for example, a specific configuration as shown in FIG. Can be used. 2, reference numeral 43 denotes an interface, 44 denotes a memory management unit, 45 denotes a data storage amount detection unit, 46 denotes a memory, and 47 denotes an output control unit. The output control unit 47 of the data storage unit 21 receives the data control signal sent from the data separation unit 27 of the decoding unit 26 shown in FIG.
7, the output control unit 47 generates a control signal based on the data control signal and supplies the control signal to the memory management unit 44.

The memory management section 44 to which the control signal has been given receives the reproduction data stored in the memory 46 from the reproduced data.
An address signal for reading predetermined reproduction data to be decoded by the decoding unit 26 is supplied to the memory 46, and a control operation is performed so that the predetermined reproduction data is read from the memory 46. Then, the reproduction data read from the memory 46 is supplied to the data separation unit 27 of the decoding unit 26 via the memory management unit 44 and the output control unit 47. As described above, in response to the request from the decoding unit 26, the reproduced data is read from the memory 46 and stored in the decoding unit 26 in accordance with the request from the decoding unit 26 as described above. It is reduced by supplying.

As described above, the reproduction data output from the signal reproducing unit 50 and supplied to the memory management unit 44 of the data storage unit 21 is transmitted from the reproduction control circuit 23 of the reproduction control unit 22 to the data storage unit 21. Interface 43
When the data is stored in the memory 46 under the control operation of the write control signal supplied to the memory management unit 44 via the memory management unit 44, the data storage amount of the memory 46 increases. The data storage amount in the memory 46 is detected by a data storage amount detection unit 45 connected to the memory management unit 44, and the data storage amount of the memory 46 detected by the data storage amount detection unit 45 is calculated. Correspondingly generated signal (as described above, information indicating how much the storage amount of the memory 46 satisfies the preset data amount ... The information may be a signal corresponding to “information related to the degree” or “satisfaction degree”. Information on the degree of sufficiency of the memory 46 can also be easily obtained by, for example, calculating the write address value and the read address value of the memory 46 (see Japanese Patent Application Laid-Open No. 1-119663).

FIG. 4A shows how the amount of data stored in the memory 46 provided in the data storage unit 21 is reduced when the variable transfer rate data reproducing apparatus of the present invention performs a reproducing operation. FIG. 5A is a diagram showing an example of a change, and in FIG. 4A, the horizontal axis indicates time, and the vertical axis indicates accumulated data amount. And Ma shown on the vertical axis
In each display such as x, Mid, Min, etc., a predetermined maximum stored data amount set for the memory 46 of the data storage unit 21 is indicated by Max, and a predetermined maximum set for the memory 46 of the data storage unit 21 is set. The obtained minimum accumulated data amount is indicated by Min, and the predetermined maximum accumulated data amount Max set for the memory 46 of the data accumulation unit 21 and the predetermined minimum accumulated data amount Min are further defined. The intermediate stored data amount is shown as Mid. Data storage unit 2 shown in FIG.
1 in the data storage amount detection unit 45 in FIG.
The three types of accumulated data amounts Max, Mid,
The output signal corresponding to Min is output to the interface 43.
To supply it.

The signals shown in FIGS. 4B to 4D respectively correspond to the data stored in the memory 46 provided in the data storage unit 21 during the reproducing operation of the variable transfer rate data reproducing apparatus of the present invention. For example, assuming that the amount has changed on the time axis in a state as shown in FIG. 4A, three types of stored data amounts Min, output from the data storage amount detection unit 45 in the data storage unit 21 This is an example of a signal output in correspondence with Mid and Max. Further, the data of the data storage amount of the memory 46 detected by the data storage amount detection unit 45 is supplied to any appropriate display means, for example, a liquid crystal display, a numerical display using LEDs, or other suitable display. And the memory 46
It is a preferred embodiment that the data storage amount in is displayed on the display.

Incidentally, the data amount of the recording data by the variable transfer rate data reproduced from the recording medium 1 by the optical pickup 3 of the signal reproducing section 50 in the variable transfer rate data reproducing apparatus of the present invention is, for example, as shown in FIG. As shown in FIG. 5, the data amount of the reproduced data also fluctuates on the time axis as shown in FIG. 5B. Referring to FIG. 4 which also shows an example of a change in the amount of data stored in the memory 46 provided in the storage unit 21 and an explanatory diagram relating to the variable transfer rate data shown in FIG. The reproducing operation of the variable transfer rate data reproducing device of the invention will be described.

In the variable transfer rate data reproducing apparatus according to the present invention, the information for starting the reproducing operation is not input to the operation unit 24 in the reproducing control unit 22 of the variable transfer rate data reproducing apparatus. Naturally, the amount of data stored in the memory 46 provided in the data storage unit 21 is 0, like the amount of data stored at the time indicated as the start of playback device operation in FIG.
Further, even after the information of the start of the reproduction operation is input to the operation unit 24 in the reproduction control unit 22 and the reproduction apparatus starts the operation, the reproduction from the recording medium 1 is performed by the optical pickup 3 of the signal reproduction unit 50. The recorded data is signal-processed by the signal processing unit 14, is supplied to the data storage unit 21 as reproduction data, and is stored in the memory 46 before the start of the reproduction operation. In a part of the period “Start”, the amount of data stored in the memory 46 provided in the data storage unit 21 is zero.

The data stored in the memory 46 provided in the data storage unit 21 is similar to a part of the period shown as “reproduction operation start → normal reproduction operation start” in FIG. When the amount is 0, the signals output from the data storage amount detection unit 45 in the data storage unit 21 in correspondence with the three types of stored data amounts Min, Mid, and Max are as shown in FIG. ) To M shown in (d)
As in in-FLG, Mid-FLG, Max-FLG, all are in a low level state. As described above, the state in which the amount of data stored in the memory 46 of the data storage unit 21 is smaller than the predetermined minimum stored data amount Min set for the memory 46 of the data storage unit 21 is defined as the data With the data amount of the reproduction data stored in the memory 46 of the storage unit 21, the decoding operation cannot be continuously performed by the decoding unit 26. In this state, the data is supplied from the reproduction control unit 22 to the decoding unit 26. The decoding control signal is set to a low level as shown in FIG. 4E, and information for stopping the decoding operation in the decoding unit 26 is transmitted to the interface 4.
3 to the reproduction control unit 22.

The memory 4 of the data storage unit 21
If the amount of data stored in the memory 6 is equal to or smaller than the predetermined minimum stored data amount Min set in the memory 46 of the data storage unit 21, the reproduction supplied from the interface 43 to the reproduction control circuit 23 of the reproduction control unit 22. The reproduction operation of the recording data from the recording medium 1 by the optical pickup 3 of the signal reproducing unit 50 is performed by the control signal generated by the reproduction control unit 22 based on the control signal.
To be performed in preference to other operations in.
The operation of reproducing the recorded data from the recording medium 1 by the optical pickup 3 of the signal reproducing unit 50 is continued, and the signal reproducing unit 5
When the supply of the reproduction data to the data storage unit 21 starts from 0, the storage data amount of the reproduction data in the memory 46 provided in the data storage unit 21 gradually increases from the state of 0.

When the amount of data stored in the memory 46 of the data storage unit 21 exceeds the above-mentioned predetermined minimum stored data amount Min, the data storage amount detection unit 45 of the data storage unit 21 detects the three types of data described above. Of the output signals corresponding to the accumulated data amounts Min, Mid, Max, respectively, of the signals Min-F shown in FIG.
Only LG changes from the low level state to the high level state. By giving this signal change to, for example, the display means, it is possible to indicate a state where the amount of stored data in the memory 46 exceeds a predetermined minimum stored data amount Min. Further, as described above, when the data storage amount of the memory 46 is the predetermined minimum storage data amount Min set for the memory 46 of the data storage unit 21, the decoding unit 26 can perform the decoding operation continuously. I ca n’t
Also in this state, the decoding control signal supplied from the reproduction control unit 22 to the decoding unit 26 is set to the low level state as shown in FIG. Information for causing the reproduction control unit 22 is provided from the interface 43.

The memory 4 of the data storage unit 21
6, the data is reproduced from the interface 43 to the reproduction control circuit 23 of the reproduction control unit 22 even when the data storage amount in the area 6 is near the predetermined minimum stored data amount Min set in the memory 46 of the data storage unit 21. A control signal is supplied, and the operation of reproducing the recording data from the recording medium 1 by the optical pickup 3 of the signal reproducing unit 50 is performed by the control signal generated by the reproduction control unit 22 to other operations in the signal reproducing unit 50. Make it a priority. Next, when the amount of data stored in the memory 46 of the data storage unit 21 exceeds the above-described predetermined stored data amount Mid, the data storage amount detection unit 45 of the data storage unit 21 outputs the three types of data described above. Of stored data Mi
Min-FL shown in FIGS. 4 (b) and 4 (c) out of signals output in correspondence with n, Mid and Max, respectively.
The two signals G and Mid-FLG change from a low level to a high level.

The two signals Min-FLG, Mid-
The state of the signal level of the FLG allows the display device to indicate that the amount of data stored in the memory 46 exceeds the predetermined amount of stored data Mid. The memory 46
When the amount of data stored in the storage unit reaches the predetermined amount of data Mid that can be continuously decoded by the decoding unit 26, that is, the predetermined amount of stored data Mid set in the memory 46 of the storage unit 21, the decoding unit A decoding control signal in a high level state as shown in FIG. 4E for enabling the decoding operation at 26 is supplied from the reproduction control unit 22 to the MPEG decoding IC of the decoding unit 26. Interface 4
3 to the reproduction control unit 22.

As described above, when the decoding control signal is supplied from the reproduction control unit 22 to the decoding unit 26, the decoding unit 26
Then, a data control signal is sent from the data separation unit 27 to the data storage unit 21. When the data control signal sent from the data separation unit 27 of the decoding unit 26 is given to the output control unit 47 of the data storage unit 21, the output control unit 4
7 generates a control signal based on the data control signal and gives it to the memory management unit 44;
4 supplies an address signal for reading out predetermined reproduction data to be decoded by the decoding unit 26 from the reproduction data stored in the memory 46 to the memory 46, and the predetermined reproduction data is stored in the memory 46. The control operation is performed so that the data is read out from the memory. The reproduction data read from the memory 46 is supplied to the data separation unit 27 of the decoding unit 26 via the memory management unit 44 and the output control unit 47.

The data separation section 27 determines whether the playback data is playback data based on audio information or data based on image information based on information (for example, information on a header portion) included in the playback data supplied thereto. It is determined whether or not the data is playback data. If the playback data is audio information data, it is supplied to the audio buffer memory 28. If the playback data is image information data, it is supplied to the video buffer memory 28. It is supplied to the buffer memory 29. The playback data stored in the audio buffer memory 28 is transmitted from the audio buffer memory 28
The audio demodulation unit 5 is always read out at a constant transfer rate.
4 and a reproduced sound signal is output from the audio demodulation unit 54.

The reproduction data based on the image information data stored in the video buffer memory 29 is MP
Reproduced data of a data amount required for decoding by the EG decode IC is read out each time and supplied to the inverse VLC decoder 30. The above-mentioned MPE to which reproduction data to be decoded is supplied from the video buffer memory 29.
The G decode IC is a portion surrounded by a thin dashed line frame inside a thick dashed line frame indicating the decoding unit 26,
It is assumed that each unit has functions such as a decoder 30, an inverse quantization unit 31, an inverse DCT unit 32, an adder 33, switches 34 and 40, an averaging circuit 35, motion compensation circuits 36 and 37, and frame memories 38 and 39. It is configured. MP above
The reproduction signal decoded by the EG decode IC is subjected to predetermined signal processing in a signal processing section 41 and then output to an output terminal 4.
3 is output. As the MPEG decoder IC, M
By using the PEG2 decoder, the decoding operation of the variable transfer rate data is easily performed.

That is, the reproduction data based on the image information data read from the video buffer memory 29 and supplied to the MPEG decoding IC is decoded by the inverse VLC decoder 30 and separated into various data. Among the various data output from the inverse VLC decoder 30, the data of the quantized discrete cosine transform coefficient is inversely quantized by the inverse quantizer 31 and then inverse discrete cosine transformed by the inverse DCT unit 32. After that, it is supplied to the adder 33. If the data subjected to the inverse discrete cosine transform in the inverse DCT unit 32 is I-picture frame data, one of the two frame memories 24 and 25 (two frame memories 24 and 25) is used as it is.
Is used in such a manner that the writing operation and the reading operation are alternately performed every frame.

If the data output from the inverse DCT unit 32 is P-picture frame data, a corresponding position in the screen of the image data stored in one predetermined frame memory (for each macro block) (The position where motion compensation has been applied)
It is stored in the other frame memory. Further, if the data output from the inverse DCT unit 32 is frame data of a B picture, the data is added to the motion-compensated predicted pixel value using the motion vector prepared in each of the two frame memories. The reproduced image data is output without being stored in the frame memory. When the frame data of the I and P pictures is being processed, the reproduced image data is output from the frame memory which is not currently being written. The switch 34 performs a switching operation in accordance with the macroblock type information, and the switch 34 performs a switching operation in accordance with the screen type information. The switch 40 sends reproduced image data to the signal processing unit 41.

The MPEG decoding IC in the decoding section 26 performs the decoding operation by sequentially reading out the reproduction data of the data amount required for decoding from the video buffer memory 29 on the time axis as described above. Therefore, the data amount of the reproduction data stored in the video buffer memory 29 is reduced by reading. In order for the decoding operation of the reproduction data in the decoding unit 26 to be performed well, the reproduction data used for the decoding operation in the decoding unit 26 is always stored in the video buffer memory 29 with a sufficient data amount. Need to be done. Therefore, in the video buffer memory 29, when the storage amount of the reproduction data in the video buffer memory 29 becomes equal to or less than the predetermined storage amount, the data control signal is transmitted to the data storage unit 21 via the data separation unit 27. Send out.

When the data control signal sent from the data separation unit 27 of the decoding unit 26 is given to the output control unit 47 of the data storage unit 21, the output control unit 47 generates a control signal based on the data control signal. Memory management unit 44
The memory management unit 44 sends an address signal for reading predetermined reproduction data to be decoded by the decoding unit 26 from the reproduction data stored in the memory 46 to the memory 4.
6 and performs a control operation to read the predetermined reproduction data from the memory 46. The reproduction data read from the memory 46 is transmitted to the memory controller 44 and the output control unit via the memory management unit 44 and the output control unit. The reproduced data is supplied to the data separation unit 27 of the decoding unit 26 and
9 is stored.

FIG. 5 illustrates the state of the data control signal intermittently transmitted on the time axis from the data separation unit 27 of the decoding unit 26 with the decoding operation in the decoding unit 26 as described above. 5 (e), the data control signal shown in FIG. 5 (e) has a low level period during which the reproduction data is read out from the memory 46 in the data storage unit 21, and a high level. Period corresponds to a suspension period in which the reproduction data is not read from the memory 46 in the data storage unit 21. In addition, (f) of FIG.
Is an example of an image output to be obtained by the read data read out as described above. In the figure, the image content is illustrated by English characters such as A to D, and the image is displayed from left to right on the screen. This shows the state of the moving image content.

The amount of data reproduced per unit time from the recording medium 1 by the optical pickup 3 of the signal reproducing unit 50 in the variable transfer rate data reproducing apparatus of the present invention is determined by the decoding unit 26 at the predetermined unit time. The reproduction data output from the signal reproduction unit 50 and sequentially supplied to the memory management unit 44 of the data storage unit 21 is stored in the memory as it is. 46, a memory having a storage capacity large enough to store the total amount of data stored in the recording medium 1 is stored in the memory 4.
6 must be used, but it is currently difficult to implement a reproducing apparatus having a memory having such a large storage capacity. Therefore, in the variable transfer rate data reproducing apparatus of the present invention, the data storage unit 21
In the state where the reproduction data of the data amount which is not excessive or short is always read from the memory 46 for the decoding operation in the decoding unit 26, the storage data amount of the reproduction data stored in the memory 46 of the data storage unit 21 By a substantially intermittent reproduction operation from the recording medium 1 so that the state does not greatly exceed the storage amount between the predetermined maximum storage amount Max and the predetermined minimum storage amount Min. In addition, continuous reproduction data without disorder in the data arrangement order is stored in the memory 46 of the data storage unit 21.

Thus, the memory 4 of the data storage unit 21
The stored data amount of the reproduction data stored in the memory 6 changes in a small range on the time axis as illustrated in, for example, FIG. When the accumulated data amount of the reproduction data stored in the memory 46 of the data accumulation unit 21 exceeds a predetermined maximum accumulation amount Max, the data accumulation amount detection unit 45 of the data accumulation unit 21 determines , The three types of stored data amounts Min, M
All of the signals Min shown in FIGS. 4B to 4D among the signals output corresponding to id and Max, respectively.
-FLG, Max-FLG are at a high level.

The three signals Min-FLG, Mid-
Since all of FLG and Max-FLG are at the high level, a state where the amount of data stored in the memory 46 exceeds the predetermined amount of stored data Max can be indicated on the display. A playback control signal is supplied from 43 to a playback control circuit 23 of the playback control unit 22, and the control signal generated by the playback control unit 22 is used to record data from the recording medium 1 by the optical pickup 3 of the signal playback unit 50. The reproduction operation is interrupted so as to be in a standby state. 4A to 4F clearly show the correspondence between the amount of data stored in the memory 46 of the data storage unit 21 and the operation state of the playback device. .

When the amount of data stored in the memory 46 exceeds a predetermined amount of stored data Max, the operation of reproducing the recorded data from the recording medium 1 by the optical pickup 3 of the signal reproducing unit 50 is interrupted and the apparatus enters a standby state. Then, the optical pickup 3 during the period when the reproduction operation is interrupted (standby period) is, as described above, a recording mark formed in a spiral shape by the thin solid line shown in FIG. 6B. With respect to (4), an operation is performed in which the recording traces indicated by the dotted lines in the diagram of FIG. 6B are continuously tracked one after another by the operation of the tracking control system. Next, when the accumulated data amount of the memory 46 falls below the predetermined accumulated data amount Max, the data accumulation amount detection unit 45 of the data accumulation unit 21 outputs the data of the aforementioned 3
Of the signals output corresponding to the types of accumulated data amounts Min, Mid, and Max, only the two signals Min-FLG and Mid-FLG shown in FIGS. 4B and 4C are at the high level. In this state, the reproduction control circuit 23 of the reproduction control unit 22
And the control signal generated by the reproduction control unit 22 controls the operation of reproducing the recording data from the recording medium 1 by the optical pickup 3 of the signal reproduction unit 50. To be performed in preference to the above operations.

As a result, the period during which the reproduction operation is interrupted (standby period) ends, and the reproduction operation by the optical pickup 3 is restarted. When the reproducing operation is resumed in this way, as described above, the recording data to be reproduced following the recording data reproduced by the optical pickup 3 immediately before the point in time when the reproducing operation was interrupted, is described. An operation capable of driving and displacing the optical pickup 3 to a position at which reproduction is possible is performed by an operation of a tracking servo system in an optical pickup control system provided in the signal reproducing unit 50 (for example, tracking by a kick pulse or a kick back pulse). 3) and / or the operation of the coarse motor system. Therefore, even if the reproduction operation is interrupted repeatedly, the reproduced data to be reproduced remains in the state shown in FIG.
As shown in (a), the data contents are correctly aligned in a predetermined order. FIG. 3B shows, for reference, the order of alignment of print data on a print medium.

[0075]

As apparent from the above description, the variable transfer rate data reproducing apparatus according to the present invention has a high code amount per predetermined time for a moving image, which is changed according to the information amount. The variable transfer rate data obtained by the efficiency coding is used to reproduce the record data of the recording medium in which the record data is recorded using the highest transfer rate in the change range of the transfer rate as the record data. When reproducing by the element, the reproducing element performs an operation so as to continuously track the recording trace by the operation of the tracking control system during the period when the reproducing operation is interrupted (standby period), and is also interrupted. When the reproducing operation is resumed, the reproducing element is driven and displaced to the position of the reproducing position element immediately before the point at which the reproducing operation was interrupted, and the reproduction in the signal reproducing unit is repeated. The device, recorded data read from the recording medium during playback is to signal processing is stored in the memory of the data storage unit as the playback data, the data control signal applied to the data storage unit from the decoding unit,
The reproduction data stored in the data storage unit is supplied to the decoding unit, and the decoding unit performs a decoding operation on the variable transfer rate data so as to output the reproduction signal without interruption. The readout of the reproduction data supplied from the memory of the section to the decoding section is performed, so that even if the storage amount of the reproduction data in the memory of the data storage section changes, the storage amount of the reproduction data in the memory of the data storage section becomes smaller. Playback is performed based on a playback control signal generated by the data storage unit so that the storage amount does not greatly exceed the storage amount between the predetermined maximum storage amount and the predetermined minimum storage amount. The control unit controls the signal reproducing unit to perform the reproducing operation intermittently, and further, the reproduction control unit controls the signal reproducing unit. As the contents of the recording data read from the recording medium intermittently performed, it is performed by the signal reproducing unit correctly aligned state in a predetermined order Te,
In addition to controlling the operation of the signal reproducing unit, the writing operation of the memory in the data storage unit is controlled, and the decoding operation in the decoding unit is controlled by a decoding control signal given from the reproduction control unit to the decoding unit. Therefore, in the variable transfer rate data reproducing apparatus according to the present invention, the data control signal provided from the decoding unit to the data storage unit can cope with a sudden change in the code amount for each image (frame) generated in a relatively short time. Then, the reproduction data can be supplied from the data storage unit to the decoding unit, and the data storage unit can be used for a change in the data amount that occurs for each of a plurality of image unit groups and that occurs for a relatively long time. Since the playback control unit can control the playback operation in the signal playback unit based on the playback control signal generated in the And changes in the amount of data in a short period of time,
For both long-term data volume changes,
The continuity of the decoding operation in the decoding unit can be maintained well, a continuous moving image signal can be output stably from the decoding unit, and the signal reproducing unit performs intermittent reproducing operation to record data from the recording medium. At the time of reproduction, without causing the reproducing element of the signal reproducing unit to perform a track jump by one recording trace for the reproducing element of the signal reproducing unit during the standby period in the reproducing operation. The recording trace is tracked in a state where the tracking control is performed until immediately before the start of reading of the next recording data, and the reproduction operation is interrupted when resuming the reproduction operation which has been suspended after the standby period has been completed. Since the reproducing element is driven and displaced by the seek operation to the position of the reproducing position element immediately before the point in time of the reproduction, the amount of data read from the recording medium by the signal reproducing unit and the decoding unit Even when the ratio with the data processing amount is large, only one seek operation of the reproducing element is performed. Therefore, the problem in the conventional device, that is, the actuator is forcibly driven and controlled in the conventional device. By increasing the number of times, the stress applied to the support mechanism of the actuator, the drive coil, and the like increases, and the problem that the life of each of the above-described components is shortened,
In the conventional device, a frequent kickback pulse is applied to the actuator of the tracking control system, so that a significant track jump is likely to occur,
When a track jump occurs, searching for a predetermined track to be reproduced next, and moving to that track, it is cumbersome to move between many tracks, and it takes a long time before the reproduction operation is restarted. Even if time is needed,
It may be necessary to take measures to prevent the reproduction data to be supplied from the data storage unit to the decoding unit from being interrupted and the reproduction signal from being output, for example. Such a problem does not occur in the variable transfer rate data reproducing apparatus of the present invention.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a schematic configuration of a variable transfer rate data reproducing device of the present invention.

FIG. 2 is a block diagram illustrating a specific configuration example of a data storage unit.

FIG. 3 is a diagram for explaining the operation of the playback device.

FIG. 4 is a diagram for explaining the operation of the playback device.

FIG. 5 is a diagram for explaining the operation of the playback device.

FIG. 6 is a diagram for explaining a state of displacement of a reproducing element during a reproducing period and a waiting period.

FIG. 7 is a block diagram illustrating a configuration example of a conventional fixed transfer rate data reproducing device.

FIG. 8 is a diagram for explaining the operation of a conventional fixed transfer rate data reproducing device.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Recording medium, 2 ... Drive motor, 3 ... Reproducing element (optical pickup), 4 ... Laser light source, 5 ... Optical member, 6 ... Objective lens, 7 ... Actuator, 8 ... Photodetector, 9 ... Focus servo system, 10: tracking servo system, 11 ...
Coarse motion motor system, 12 ... Rotation control system, coarse motion motor, 14 ...
Signal processing unit, 15 Operation / amplification unit, 16 Sync detection / demodulation circuit, 17 Phase locked loop, 18 Error correction deinterleave circuit, 19 Random access memory, 20 Subcode reader, 21, 49 Data Storage unit, 22, 51 ... reproduction control unit, 23 ... reproduction control circuit,
26, 52: decoding unit, 42, 53: reproduction signal output terminal, 43: interface, 44: memory management unit, 4
5: data storage amount detection unit, 46: memory, 47: output control unit, 48, 50: signal reproduction unit, 55: collimator lens, 56: polarization beam splitter, 57: quarter-wave plate, 58: cylindrical lens,

Claims (1)

(57) [Claims] 1. A variable transfer rate data obtained by performing high-efficiency encoding so as to change at least a code amount per predetermined time of a moving image in accordance with an information amount, and a transfer rate change range described above as recording data. A variable transfer rate data reproduction device from a recording medium that has been recorded using the highest transfer rate in the above, comprising at least a reproduction element driven and displaced by an actuator of a tracking control system and a signal processing unit A signal reproducing unit, a data storage unit for storing reproduction data reproduced by the signal reproduction unit, a decoding unit for decoding reproduction data supplied from the data storage unit, the signal reproduction unit and data A playback control unit that controls the operation of the storage unit and the decoding unit, and in a state where the playback signal is continuously output from the decoding unit. Means for providing a data control signal from the decoding unit to the data storage unit for supplying from the memory of the data storage unit the reproduced data having a data amount such that the decoding operation can be performed on the variable transfer rate data in the decoding unit. The amount of reproduced data stored in the memory of the data storage unit, which is changed by reading of the reproduced data supplied from the memory of the data storage unit to the decoding unit by the data control signal, is set to a predetermined maximum. And the reproduction operation performed intermittently so as not to greatly exceed the storage amount between the storage amount of the storage medium and the predetermined minimum storage amount. A reproduction control signal provided from the data storage unit to the reproduction control unit so that the reproduction control unit can perform the operation in a predetermined order and correctly aligned. Means for controlling the operation of the signal reproducing unit based on the reproduction control signal, and controlling the intermittent reproduction operation in the signal reproducing unit based on the reproduction control signal. During the interruption period, means for allowing the reproducing element to continuously track the recording trace by the operation of the tracking control system, and a reproduction control unit based on the reproduction control signal When controlling the intermittent reproduction operation in the signal reproduction unit, when the reproduction operation which has been interrupted is resumed, the reproduction element is driven to the position of the reproduction position element immediately before the time when the reproduction operation was interrupted. Means for sequentially supplying a plurality of kick pulses to an actuator of a tracking control system so as to be displaced,
Means for controlling the write operation of the memory in the data storage unit by a write control signal given from the playback control unit to the data storage unit, and means for controlling the decoding operation in the decoding unit by a decode control signal given from the playback control unit to the decoding unit A variable transfer rate data reproducing device comprising: