JPH07336640A - Disk recording device - Google Patents

Abstract

PURPOSE:To attain continuous reproduction of coded data with different compression rates for each period while avoiding an overflow/underflow of a buffer memory and to attain variable speed reproduction. CONSTITUTION:A read control circuit 14 reads data from a memory 9 at a transmission rate corresponding to a compression rate upon a request from a decoding circuit 10. A storage quantity detection circuit 15 detects a data storage quantity of the memory 9 and moves a pickup 3 inward by one track when an overflow is going to be caused, the circuit 15 makes idle read by one rotation and then a write control circuit 13 restarts data write to the memory 9. Furthermore, the memory 9 has a capacity larger than the data quantity read for a time requiring one rotation of an outermost circumference at a data transmission rate from the disk 1 thereby avoiding an underflow. A retrieval circuit 20 retrieves directly data required for variable speed reproduction from data read from the disk 1, a decoding circuit 10 decodes the data and the result is displayed and then variable speed reproduction is attained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a disc reproducing apparatus, and more particularly to a disc reproducing apparatus for reproducing encoded data encoded under a varying compression rate.

[0002]

2. Description of the Related Art As a typical example of a system for recording and reproducing digital data using a disc, Japanese Patent Laid-Open No. 1-20
As described in Japanese Patent No. 0793, there is a CD-ROM in which data is recorded so that it can be read optically. C
The D-ROM has data recorded on the same optical disk as an audio CD, and the data has recording tracks and is spirally recorded on the disk. As described in the above publication, the data recording format constitutes a minimum unit called a frame, and each frame is composed of synchronization data, subcodes, digital data of main information, and error correction code. . further,
Recording on the disk is continuous by taking a sector structure in which the digital data of 98 frames (2352 bytes) is used as one sector, and each sector is 12 bytes of synchronization data and 4 bytes of header data indicating an address and a mode. , 2048 bytes of digital data and 288 bytes of error detection / correction code. However, the 2340 bytes excluding the synchronization data are recorded after being scrambled in order to average the power spectrum of the signal.

Here, in the case of highly efficient encoding of a moving image signal or the like to obtain encoded data, changing the compression rate means that the amount of data that can be transmitted changes per unit time. This is equivalent to changing the transmission rate of. However, basically, data is read from the disk at a constant linear velocity, and the transmission rate is fixed. Therefore, regarding the encoded data to be recorded,
Encoding must be performed at a compression rate that matches the average transmission rate with the fixed transmission rate of the disc. On the other hand, the moving image signal does not have the same property at all times.For example, it is better to lower the compression rate for a scene with a lot of movement and increase the compression rate for a scene with little movement, so that the deterioration as a whole becomes less noticeable. May lead to a decrease in

As an example of a method for reproducing coded data whose transmission rate varies using the above-mentioned CD-ROM, as described in the above publication, the rotation control of the motor is controlled according to the transmission rate information. There was a method of changing the transmission rate from the disc. Further, when the disc has a fixed transmission rate, as described in the above-mentioned publication, there is a method of skipping or pausing transmission of encoded data for a certain period of time. It realized a transmission rate slower than the rate.

[0005]

In the above prior art, when data is read out from the disk at a fixed transmission rate, the data transmission rate is changed in accordance with the variation of the encoded data amount at the time of encoding, and the data is stored in the buffer memory. The data amount of is controlled, and with regard to handling encoded data compressed at a transmission rate that varies from period to period,
It was not considered in particular. Further, no consideration has been given to variable speed reproduction of encoded data compressed at such a transmission rate that varies with each period.

Therefore, a first object of the present invention is to read coded data from a disk at a fixed transmission rate, while depending on the respective compression rates, coded data coded at a compression rate that varies from period to period. Another object is to provide a disc reproducing apparatus capable of reproducing at a high transmission rate.

A second object of the present invention is to perform control such that the buffer memory does not overflow or underflow when the coded data is reproduced at a transmission rate corresponding to a fluctuating compression rate. It is an object of the present invention to provide a disc reproducing apparatus that enables determination of the optimum buffer memory capacity.

Further, a third object of the present invention is to perform variable speed reproduction by retrieving and decoding coded data which can be decoded from the data read from the disk when the encoded data is reproduced at a variable speed. It is to provide a reproducible disc reproducing device.

Further, a fourth object of the present invention is to provide a disc reproducing apparatus capable of operating with a minimum number of memories, including some memories necessary for decoding the coded data. It is in.

[0010]

In order to achieve the above-mentioned first object, according to the present invention, a buffer memory is provided at a transmission rate according to a compression rate of encoded data according to a request from a decoding means of encoded data. It is assumed that the data is read from the memory, and write control means and read control means for the buffer memory are provided for that purpose.

In order to achieve the above-mentioned second object, in the present invention, a storage amount detecting means for detecting the data storage amount of the buffer memory is provided, and when the storage amount exceeds the capacity of the buffer memory, A control means for interrupting writing to the buffer memory and moving the pickup to the inside of one track at the same time is provided, and writing to the buffer memory is performed after the disk makes one round and returns to the position immediately before the movement of the pickup. Try to restart. Further, the buffer memory has a capacity equal to or more than the amount of data read at the transmission rate of data from the disk in the time required for the pickup to make one round of the outermost track on the disk.

In order to achieve the above-mentioned third object, in the present invention, the control means for moving the pickup to a predetermined position in response to the variable speed reproduction request, and the code read from the disk after the movement. Retrieval means for retrieving desired encoded data from the encoded data and outputting the encoded data to the decoding means is provided.

In order to achieve the above-mentioned third object,
In the present invention, a control means for moving the pickup to a predetermined position in response to a variable speed reproduction request, and a search means for searching for the desired encoded data from the encoded data read from the disc after the movement. A variable speed reproduction buffer memory for temporarily storing the searched encoded data, and a control means for reading the encoded data from the variable speed reproduction buffer memory according to a required speed of the variable speed reproduction and outputting it to the decoding means. To provide.

In order to achieve the fourth object, according to the present invention, a reception buffer memory, a frame memory and the like attached to the decoding means for encoded data are also used as the buffer memory and the variable speed reproduction buffer memory. The configuration is as follows.

[0015]

The writing control means writes the encoded data in the buffer memory at the transmission rate from the disk, and the decoding means extracts the transmission rate information contained in the encoded data. Therefore, the reading control means uses the transmission rate information. It is possible to read the encoded data from the buffer memory at a transmission rate according to.

Further, the accumulated amount detecting means detects the accumulated amount in the buffer memory, and the writing control means interrupts the writing when the accumulated amount exceeds the capacity of the buffer memory, so that the pickup position is inside one track. Move to and the disc is 1
Since the writing is restarted after waiting for the period of time for the cycle, overflow of the buffer memory can be avoided. Further, since the time required for the disk to make one round is the longest when the pickup is on the outermost track of the disk, the buffer memory having a capacity corresponding to the amount of data read at this time at the transmission rate from the disk. If you prepare, you can avoid the underflow of the buffer memory.

Further, the moving means of the pickup moves the pickup to the head position of the sector in response to the request for the variable speed reproduction, the searching means searches the sector, and the encoded data necessary for the variable speed reproduction, for example, The existence of the decodable coded data is checked by using the coded data that can be decoded only from the coded data or the already decoded signal. If such encoded data exists,
Data is output to the decoding means at the transmission rate from the disc, and if it does not exist, the pickup moving means repeats the processing of moving the pickup to the predetermined sector head position again. In this way, the encoded data required for the variable speed reproduction can be retrieved and output to the decoding means, so that the variable speed reproduction of the encoded data compressed at the transmission rate that changes for each period becomes possible. .

Furthermore, by using the reception buffer memory and the frame memory associated with the decoding means also as the buffer memory, it is possible to reduce the number of memories in the entire apparatus.

Further, by using the reception buffer memory and the frame memory associated with the decoding means also as the buffer memory and the variable speed reproduction buffer memory, it is possible to reduce the number of memories in the entire apparatus.

[0020]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing a first embodiment of a disc reproducing apparatus according to the present invention for reproducing a moving image signal from a CD-ROM, and 1 is a CD on which encoded data of the moving image signal is recorded. -Disk as a ROM, 2 is a motor for rotating the disk 1 at a constant linear velocity, and 3 is a fixed transmission rate rp [bps] (bits) of a recording signal of the disk 1.
per second) pickup 4 reads a preamplifier circuit that amplifies the signal read by the pickup 3 and shapes the waveform, 5 pickup servo circuit that controls the pickup 3, 6 error correction digital data from the preamplifier circuit 4 Such as a digital signal processing circuit for processing in accordance with the recording format of the disk 1, a motor servo circuit 7 for rotating the motor 2 at a constant linear velocity, 8
Is a de-scramble circuit that detects a sync signal from the data processed by the digital signal processing circuit 6 and descrambles it, and outputs it as encoded data. 9 is a write / read circuit by the write control circuit 13 and the read control circuit. Input / output of data is controlled by the address. Capacity M [bi
ts] buffer memory, 10 is a decoding circuit for extracting transmission rate information from the encoded data read from the buffer memory 9 at a variable transmission rate rb [bps], and decoding moving image data, and 11 is a decoding circuit 10 A frame memory 12 associated with the D / A (digital / digital) for converting the decoded moving image data into an analog video signal.
(Analog) conversion circuit, 13 generates a write address,
A write control circuit for controlling data writing to the buffer memory 9, 14 generates a read address according to the transmission rate information from the decoding circuit 10, and controls data reading from the buffer memory 9 to the decoding circuit 10. A read control circuit, 15 is a storage amount detection circuit for detecting the data storage amount by monitoring the difference between the write address and the read address of the buffer memory 9, 16 is a microcomputer for system control, and 17 is an output terminal.

First, the encoded data recorded on the disc 1 in FIG. 1 will be described with reference to FIG.
However, FIG. 2 is a diagram showing how the average transmission rate changes when the moving image signal is encoded at an appropriate compression rate for each period, and the average transmission rate r1 [bp during the periods t1 to t2.
data A compressed at s], periods t2 to t3 are data B compressed at an average transmission rate r2 [bps], period t3
.About.t4 indicates data C compressed at the average transmission rate r3 [bps]. Note that r2>r1> r3, and these data A to C are continuously recorded on the disc 1 including the transmission rate information.

Transmission rate rp [bp from the disk 1
[s] is set under the condition of rp ≧ r2 and is fixed. Therefore, for example, if rp = r2, the time required to read the data B from the disk 1 is (t
3-t2) [sec], but to read the data A, (t2-t1) × r1 / r2 [sec], and to read the data C, (t4-t1) × r3 / r2 [sec]. In addition, it takes less time than the actual playback time. In order to absorb such a difference between the read time from the disc 1 and the actual reproduction time, the transmission rate rb [bps] of data read from the buffer memory 9 is variable.

The read operation will be described in detail with reference to FIG. However, FIG. 3 is a block diagram showing a specific configuration of the decoding circuit 10 in FIG. 1 and its peripheral portion.
The same symbols are attached to the portions corresponding to.

By the way, as a current moving picture signal coding method, a method in which orthogonal transformation, quantization and variable length coding are combined with interframe prediction is generally used, and an MPEG method of ISO (International Organization for Standardization) is also used. The method is based on this. FIG. 3 shows a case in which the MPEG circuit is used as the decoding circuit 10, and 101 is a reception buffer memory for absorbing a variation in the amount of encoded data required for each image frame within a unit time. , 102 is a variable length decoding circuit, 103 is an inverse quantization (IQ) circuit, 10
Reference numeral 4 is an inverse discrete cosine transform (IDCT) circuit, 105 is an adder, and 106 is a motion compensation (MC) circuit.

The coded data coded by the MPEG system has a structure in which the transmission rate information is included in the head portion, and when the transmission rate fluctuates every certain period as in this embodiment, the change occurs. Transmission rate information is included for each. When such coded data is supplied from the buffer memory 9 to the variable length decoding circuit 102 via the reception buffer memory 101, this transmission rate information is decoded and output to the read control circuit 14. The read control circuit 14 generates a read address according to the transmission rate information, and always reads data from the buffer memory 9 to the decoding circuit 10 at an appropriate transmission rate.
By such processing, even if encoded data having different compression rates are continuously read from the disc 1, reproduction can be performed at a transmission rate corresponding thereto.

On the other hand, other main data decoded by the variable length decoding circuit 102 are IQ circuit 103 and IDCT circuit 1.
In 04, IQ processing and IDCT processing are performed respectively, and the adder 1
In 05, it is added with the reference frame image data after the MC processing, and then output as final image data. The frame memory 11 is necessary for performing MC processing in the MC circuit 106 and has a capacity of at least two frames of image data or more.

Next, the operation related to the capacity of the buffer memory 9 in FIG. 1 will be described with reference to FIGS. 4 and 5.

FIG. 4 shows the state of the tracks on the disk 1, which are (m-1), m, (m + 1), ...,
(M + n), (m + n + 1) [where m and n are natural numbers]
Represents sectors, and P1 to P3 represent read positions of the pickup 3.

FIG. 5 shows how data is transmitted. FIG. 5A shows the arrangement of data read from the disk 1 by the pickup 3, and FIG. 5B shows the accumulated amount detection circuit 15. FIG. 7C shows how the storage amount of the buffer memory 9 is detected, and FIG. 7C shows how data is written from the descramble circuit 8 to the buffer memory 9 by the write control circuit 13. ) D1
d3 schematically represents the storage amount in the buffer memory 9.

In FIG. 4, since the tracks on the disc 1 are read from the inside to the outside, the position of the pickup 3 changes in the order of P1-P2-P3, and the arrangement of the read data is as follows. As shown in FIG. 5 (a), it is sequentially continuous from m to (m + n). In this case, the storage amount of the buffer memory 9 is operated in a state where there is a margin equal to or less than the capacity, as indicated by d1 in FIG. However, the transmission rate rb [bp of the data from the buffer memory 9 is higher than the transmission rate rp [bp] of the data from the disk 1.
[s] is a low value (rp> rb), a certain time (t
In 5), the buffer memory 9 becomes a state in which the data storage amount becomes full and the reading cannot be done in time, and further writing cannot be performed, as indicated by d2 in FIG. 5D. , Is an overflow).

The accumulated amount detection circuit 15 is a write control circuit 13
The amount of data accumulated in the buffer memory 9 is detected by monitoring the difference between the write address from the read address and the read address from the read control circuit 14. As shown in FIG. 5B, when the storage amount detection circuit 15 detects full in the buffer memory 9 at time t5, the microcomputer 16 interrupts the generation of the write address by the write control circuit 13, As shown in c), the data writing to the buffer memory 9 is temporarily stopped. And at the same time,
The microcomputer 16 causes the pickup servo circuit 5 to move the pickup 3 inward by one track so that the read-out position of the pickup 3 moves again in the order of P1-P2-P3. Until time t6 when the position address of the pickup 3 on the disc 1 returns to the position before the movement, m to (m +
The data of n) is read twice, but FIG. 5 (c)
As shown in FIG.
Since data writing to the buffer memory 9 is resumed only at time t6 without writing data to, the arrangement of data written in the buffer memory 9 is ... (m + n), (m + n + 1),
… And so on.

Further, between the times t5 and t6, since the data reading from the buffer memory 9 to the decoding circuit 10 is performed at the transmission rate rb [bps], the accumulated amount of the buffer memory 9 at the time t6 is As indicated by d3 in FIG. 5D, rb × (t6−t5) from the full state.
It will be restored to the state where only [bits] are available.

Here, considering the capacity of the buffer memory 9, if it becomes completely empty between times t5 and t6,
No more data can be read (this is called underflow). The transmission rate is rp ≧ rb, and (t6−t5) [sec] is longest when the read position of the pickup 3 is at the outermost circumference of the disk 1. Therefore, the time required for the disk 1 to make one rotation at that time Is set to (t6-t5) = T [sec], the capacity M of the buffer memory 9 is at least M ≧ (rp × T) [bit
[s], underflow can be avoided.

For example, data is read from the disk 1 at a transmission rate rp = 9 [Mbps], and a linear velocity v =
At 3.6 [m / sec], since the outermost circumference length of the CD-ROM is l = 0.364 [m], M = rp × l
/V=9×0.364/3.6=0.91 [Mbit
It is understood that it is sufficient to have a buffer memory of [s] or more.

As described above, in this embodiment, the overflow of the buffer memory can be avoided by controlling the data reading from the disk by monitoring the accumulated amount of the buffer memory, and this control is performed. Therefore, by ensuring a sufficient capacity, underflow of the buffer memory can be avoided.

FIG. 6 is a block diagram showing the essential parts of a second embodiment of the disk reproducing apparatus according to the present invention, in which 18 is a memory, and the parts corresponding to those in FIG. The description is omitted.

The memory 18 has a new structure in this embodiment, and the buffer memory 9 and the reception buffer memory 101 are combined into one memory 18.
In this case, the read control circuit 14 directly controls the data read from the memory 18 to the variable length coding circuit 102, and normally, the capacity of the reception buffer memory 101 is set smaller than the capacity of the buffer memory 9. Therefore, the capacity of the memory 18 depends on the method of determining the capacity of the buffer memory 9.

As described above, in this embodiment, the number of memories of the entire apparatus can be reduced by sharing the two memories.

FIG. 7 is a block diagram showing the essential parts of a third embodiment of the disk reproducing apparatus according to the present invention, in which 19 is a memory, and the parts corresponding to those in FIG. The description is omitted.

In this embodiment, a new structure is a memory 19, which includes a buffer memory 9, a reception buffer memory 101, and a frame memory 11 as one memory 19.
It is also used as. This embodiment is different from the second embodiment shown in FIG. 6 in that the data to be stored in the memory 18 and the frame memory 11 are different, such as encoded data and image data. Then, it must be able to be used as both memories at the same time. However, since the frame memory 11 has a capacity of 2 frames of image data, if a capacity of 2.4 [Mbits] is required, for example, a memory of 4 [Mbits] is used as the general-purpose memory. Become. Therefore, by using the remaining 1.6 [Mbits] as the buffer memory 9 and the reception buffer memory 101, it is possible to use them in common.

As described above, according to this embodiment, the number of memories of the entire apparatus can be further reduced by sharing the three memories.

FIG. 8 is a block diagram showing a fourth embodiment of the disc reproducing apparatus according to the present invention, in which reference numeral 20 is a search circuit, and the portions corresponding to those in FIG. Omit it.

The search circuit 20 has a new structure in this embodiment. In the case of normal reproduction, the first reproduction shown in FIG.
Processing similar to that in the above embodiment is performed.

A specific example of the processing operation of this embodiment in the case of variable speed reproduction will be described below with reference to FIG.

First, the microcomputer 16 receiving the variable speed reproduction request invalidates the transmission rate information output from the decoding circuit 10 and sends the data stored in the buffer memory 9 to the search circuit 20. Read control circuit 14
To control. The search circuit 20 searches the buffer memory 9 for a flag indicating the mode in which the data was encoded, for example, the encoding type (step 90).
0). If the searched coding type is a type indicating that intra-frame coding has been performed, that is, if it is an I picture (step 901), the subsequent data is decoded by the decoding circuit 1.
0, decrypt and display (step 90).
2). Then, after the decoding of the picture is completed, or when the search result of the coding type is not an I picture (step 901), it is determined whether all the data in the buffer memory 9 has been sent (step 903), and the data is sent. If not, the above processing is repeated. If it is sending (step 903), the microcomputer 16 makes the pickup 3 jump N sectors (where N is a natural number) (step 90).
4) The control signal is sent to the pickup servo circuit 5 to move it to a predetermined sector head position. The data reproduced from the disk 1 is amplified and waveform-shaped by the preamplifier circuit 4, error correction is performed by the digital signal processing circuit 6, and then the descrambling circuit 8 detects the sync signal and descrambles it. Is output to the search circuit 20. As shown in FIG. 10, the search circuit 20 searches for a coding type in the user data area in the sector (step 905), and if the searched coding type is an I picture (step 906),
The data after that is output to the decoding circuit 10, and is decoded and displayed (step 907).

Then, after the decoding of the picture is completed (step 907), or the data encoded using the bidirectional prediction such that the retrieved coding type is not the I picture but the B picture. If so (step 906), the microcomputer 16 sets the pickup 3 to N again.
A sector jump is performed (step 904) and the above processing is repeated.

Next, another specific example of the processing operation of this embodiment in the case of variable speed reproduction will be described with reference to FIG.

First, the microcomputer 16 having received the variable speed reproduction request invalidates the transmission rate information output from the decoding circuit 10 and sends the data stored in the buffer memory 9 to the search circuit 20. Read control circuit 14
To control. In the search circuit 20, the data encoded using only the data itself from the buffer memory 9 and the header data indicating a group composed of a plurality of other encoded data, for example, a GOP (Group of Picture) header are provided. Search (step 1100). And GOP
When the header is retrieved (step 1101), the coding type is retrieved from the user data area after that (step 1102). If the searched coding type is a type indicating that intra-frame coding has been performed, that is, if it is an I picture (step 1103), the data after that is sent to the decoding circuit 10 for decoding and display. (Step 1104). Then, after the decoding of the picture is completed, or when the GOP header cannot be searched (step 1101), or the search result of the coding type is not an I picture (step 1103).
It is determined whether or not all the data in the buffer memory 9 has been transmitted (step 1105), and if not transmitted, the above processing from step 1100 is repeated.

If it has been sent (step 1105), the microcomputer 16 makes the pickup 3 jump N sectors (step 1106) and sends its control signal to the pickup servo circuit 5 to move it to a predetermined sector head position. The data reproduced from the disk 1 is amplified and waveform-shaped by the preamplifier circuit 4, error correction is performed by the digital signal processing circuit 6, and then the descrambling circuit 8 detects the sync signal and descrambles it. Is output to the search circuit 20. Search circuit 20
Then, as shown in FIG. 12, it is searched for a GOP header in the user data area in the sector (step 110).
7) If the GOP header is retrieved (step 110)
8) Then, the coding type existing after that is searched (step 1109). If the retrieved coding type is an I picture (step 1110), the subsequent data is output to the decoding circuit 10, decoded and displayed (step 1111).

After the picture has been decoded (step 1111), or if the GOP header cannot be retrieved (step 1108), or the retrieved coding type is not an I picture (step 111).
0), the microcomputer 16 again causes the pickup 3 to jump N sectors (step 1106), and the above processing is repeated.

In this specific example, the GOP header is searched and then the coding type of the I picture is searched. In the above-mentioned MPEG, since the I picture data is coded after the GOP header, the GOP header is searched. After being processed, the subsequent data can be output to the decoding circuit 10.

The sector jump value N can be determined by the processing capability of the digital signal processing circuit or the decoding circuit.

As described above, according to this embodiment, in response to the variable speed reproduction request, the encoded data of the I picture required for the variable speed reproduction is retrieved and the data is output to the decoding means. The video can be displayed even in the variable speed reproduction.

FIG. 13 is a block diagram showing a fifth embodiment of the disk reproducing apparatus according to the present invention, in which 21 is a search circuit, 22 is a variable speed reproducing buffer memory, and the portion corresponding to FIG. The same reference numerals are given and detailed description is omitted.

In this embodiment, what is new to the first embodiment shown in FIG. 1 is a search circuit 21 and a variable speed reproduction buffer memory 22. In the case of normal reproduction, the same processing as that of the first embodiment is performed, and therefore its explanation is omitted.

A specific example of the variable speed reproduction operation of this embodiment will be described below with reference to FIG.

First, the microcomputer 16 receiving the variable speed reproduction request invalidates the transmission rate information output from the decoding circuit 10 and sends the data stored in the buffer memory 9 to the search circuit 21. Read control circuit 14
To control. The search circuit 21 searches the buffer memory 9 for a flag indicating the mode in which the data was encoded, for example, the encoding type (step 1
400). The retrieved coding type indicates that the intra-frame encoding has been performed (that is, I picture), or the type that indicates that the predictive encoding has been performed using one already decoded data (that is, I type). , P picture) (step 1401), the picture data is once written in the variable speed reproduction buffer memory 22 (step 1402). Then, the read control circuit 14 generates a read address according to the speed required for variable speed reproduction (M speed) from the microcomputer 16, and reads data from the variable speed reproduction buffer memory 22 to the decoding circuit 10. The decoding circuit 10 decodes this and displays it (step 1).
403). After the picture has been decoded, or
If the search result of the coding type is not an I picture or a P picture (step 1401), it is determined whether all the data in the buffer memory 9 has been transmitted (step 14).
04), if not sent, the above processing from step 1400 is repeated.

If all the data in the buffer memory 9 has been sent (step 1404), the microcomputer 16 causes the pickup 3 to jump N sectors (step 140).
5) The control signal is output to the pickup servo circuit 5 in order to move it to a predetermined sector head position. The data reproduced from the disk 1 is amplified and waveform-shaped by the preamplifier circuit 4, subjected to error correction and the like by the digital signal processing circuit 6, and then detected by the descrambling circuit 8 and descrambled. Is output to the search circuit 21. The search circuit 21 searches for a coding type in the user data area in the sector (step 1406). If the searched coding type is an I picture or a P picture (step 1407), the picture data is searched. Variable speed playback buffer memory 22
(Step 1408). Then, the read control circuit 14 generates a read address in accordance with the variable speed reproduction request speed (M times speed) from the microcomputer 16, reads the data from the variable speed reproduction buffer memory 22 to the decoding circuit 10, and performs decoding. The digitizing circuit 10 decodes and displays it (step 1409).

After the decoding of the picture is completed (step 1409) or if the searched coding type is not the coded data of I picture or P picture (step 1409), the microcomputer 16 picks up again. 3 jump N sectors (step 140
9) The above process is repeated.

FIG. 15 shows a specific example of the variable speed reproduction data as described above. FIG. 15A shows a video sequence, I is an I picture (intra-frame coding),
P is a P picture (one-way predictive coding from a past I or P picture), and B is a B picture (past or future I picture).
Or bi-directional predictive coding from P pictures). The coded data of the video sequence coded in this way is recorded on the disc 1 as the CD-ROM recording data shown in FIG. The encoded data of the I or P picture retrieved by the retrieval circuit 21 is shown in FIG.
As shown in (c), it is stored in the variable speed reproduction buffer memory 22. Then, the data is read from the variable speed reproduction buffer memory 22 and decoded according to the required speed of the variable speed reproduction. For example, in the case of triple speed, as shown in FIG. 15 (d), I1, P2, P3, P4, P
5, I6, P7, P8, and so on,
It can be realized by displaying. In the case of 6x speed,
This can be realized by decoding and displaying I1, P3, P5, and P7 in this order as shown in FIG. However, in this case, I6 only performs decoding.

As described above, in the fifth embodiment, the coded data of the I picture and the P picture required for the variable speed reproduction are retrieved in response to the variable speed reproduction request and output to the decoding means. As a result, the video can be displayed even in the variable speed reproduction.

The sector jump value N can also be determined by the processing capabilities of the digital signal processing circuit and the decoding circuit.

In the fifth embodiment, similarly to the fourth embodiment shown in FIG. 8, the I picture and P picture required for variable speed reproduction are coded in response to the variable speed reproduction request. By searching the data and outputting the data to the decoding means, the video can be displayed even in the variable speed reproduction. Further, in the fourth embodiment, since the I picture is searched and only that picture is displayed, the speed of variable speed reproduction is determined by the interval of the I picture. For example,
The variable speed reproduction that can be realized when the I picture interval is 15 is 15 times speed reproduction. However, in the fifth embodiment, the speed of variable speed reproduction can be determined by the interval between the I picture and the P picture. For example, the variable speed reproduction that can be realized when the interval between the I picture and the P picture is 3 is 3, 6, 9, ...

In the fifth embodiment, the buffer memory 9 and the variable speed reproduction buffer memory 22 are combined into one memory, and the reception buffer memory 101 and the variable speed reproduction buffer memory 22 are combined into one memory. Shared with the buffer memory 9 and the reception buffer memory 101.
And the variable speed reproduction buffer memory 22 can be shared by one memory, or the buffer memory 9, the reception buffer memory 101, the frame memory 11, and the variable speed reproduction buffer memory 22 can be combined by one memory. .
By thus configuring the memory so that it also serves as the memory, the number of memories in the entire apparatus can be reduced.

Further, in the above fourth and fifth embodiments, the description is made such that the buffer memory 9 is searched first during the variable speed reproduction, but the present invention is not limited to this. For example, it is possible to ignore the buffer memory 9 during variable speed reproduction.

Furthermore, in each of the above embodiments, the case of a CD-ROM in which data is recorded in a spiral track has been described. However, the present invention is not limited to this. For example, a plurality of data having concentric circles may be used. The present invention can be applied to the case of a hard disk recorded on a track.

Further, in each of the above embodiments, the case where only the moving image data is handled as the encoded data has been described, but the present invention is also applicable to the case where the encoded data in which the moving image data and the audio data are multiplexed is handled. The invention can be applied without problems.

Furthermore, in each of the above embodiments, the case where the compression rate of the encoded data recorded on the disc fluctuates in three stages has been described, but the present invention is not limited to three stages.

Furthermore, in each of the above embodiments, the MPEG system has been described as an example of the video signal encoding system, but the present invention is not limited to this.

[0070]

As described above, according to the present invention,
At the request of the decoding means, the data can be read from the buffer memory at the transmission rate according to the compression rate of the encoded data, so that the encoded data encoded under the varying compression rate can be continuously reproduced. can do.

Further, overflow of the buffer memory can be avoided by detecting the amount of data accumulated in the buffer memory and controlling the position of the pickup to perform idle reading.

Further, it is possible to determine the capacity of the buffer memory sufficient to avoid the underflow of the buffer memory from the transmission rate of data from the disk and the time required to read the outermost circumference of the disk. .

Furthermore, in the case of variable speed reproduction, the coded data to be displayed during variable speed reproduction is directly retrieved from the data reproduced from the disk and is thus decoded, so that the encoding is performed under a varying compression rate. Variable speed reproduction can be performed without considering the transmission rate of the encoded data.

Furthermore, by using some of the memories associated with the decoding means as the buffer memory and the buffer memory for variable speed reproduction, the required number of memories can be reduced, and the size and cost of the apparatus can be reduced. Can be down.

[Brief description of drawings]

FIG. 1 is a block diagram showing a first embodiment of a disc reproducing apparatus according to the present invention.

FIG. 2 is a diagram showing an example of changes in the average transmission rate of encoded data recorded on a disc.

3 is a block diagram showing a specific example of a decoding circuit in FIG.

FIG. 4 is a diagram showing an example of a state of tracks on a disc of a CD-ROM.

FIG. 5 is a diagram for explaining how data is read from a disk and data is input / output to / from a buffer memory.

FIG. 6 is a block diagram showing a main part of a second embodiment of a disc reproducing apparatus according to the present invention.

FIG. 7 is a block diagram showing a main part of a third embodiment of a disc reproducing apparatus according to the present invention.

FIG. 8 is a block diagram showing a fourth embodiment of the disc reproducing apparatus according to the present invention.

FIG. 9 is a flowchart showing a specific example of a processing operation during variable speed reproduction according to the fourth embodiment shown in FIG.

FIG. 10 is a diagram for explaining a specific example of the processing of variable speed reproduction according to the fourth embodiment shown in FIG.

FIG. 11 is a flowchart showing another specific example of the processing operation during variable speed reproduction according to the fourth embodiment shown in FIG.

FIG. 12 is a diagram for explaining another specific example of the process of variable speed reproduction according to the fourth embodiment shown in FIG.

FIG. 13 is a block diagram showing a fifth embodiment of the disc reproducing apparatus according to the present invention.

14 is a flowchart showing a specific example of the processing operation during variable speed reproduction according to the fifth embodiment shown in FIG.

FIG. 15 is a diagram showing a state of variable-speed reproduction data according to the fifth embodiment shown in FIG.

[Explanation of symbols]

 1 disk 2 motor 3 pickup 4 preamplifier circuit 5 pickup servo circuit 6 digital signal processing circuit 9 buffer memory 10 decoding circuit 13 write control circuit 14 read control circuit 15 accumulated amount detection circuit 16 microcomputer 18, 19 memory 101 reception buffer memory 102 variable Long decoding circuit 20,21 Search circuit 22 Variable speed playback buffer memory

Claims (20)

[Claims] 1. Digital data encoded from a disc in which spiral or concentric recording tracks are recorded so that digital data encoded so as to match different transmission rates for each period is also recorded. In a disc reproducing apparatus for reproducing data, storage means for temporarily storing digital data read from the disc, control means for controlling writing of the digital data in the storage means, and transmission from the digital data. Disk reproduction comprising: decoding means capable of extracting rate information; and control means for controlling the decoding means to read the digital data from the storage means at a transmission rate according to the transmission rate information. apparatus. 2. A disc in which digital data encoded so as to include transmission rate information so as to match different transmission rates for each period is recorded on spiral or concentric recording tracks at a constant linear velocity. In a disc reproducing apparatus provided with a rotating unit for rotating and a data reading unit for reading data from the disc, a storage unit for temporarily storing digital data read from the disc, and a digital unit for storing the digital data in the storage unit. Writing control means for controlling writing of data; decoding means for extracting the transmission rate information from the digital data; and decoding means for storing the digital data from the storage means at a transmission rate according to the transmission rate information. A read control means for controlling to read and a storage amount detecting means for detecting the storage amount of the storage means. When the storage amount detecting means detects that the storage amount in the storage means exceeds the capacity, the write control means stops writing the digital data to the storage means, and at the same time, The data reading means is connected to one of the recording tracks.
A disc reproducing apparatus, wherein the disc reading device is configured to be moved inward by an amount, and when the data reading unit returns to the position before the movement, writing of the digital data to the storage unit is restarted. 3. The capacity M of the storage means according to claim 2, wherein the capacity M of the storage means is a transmission rate rp for reading the digital data from the disc, and the data reading means is on the recording track at the outermost periphery of the disc. Depending on the time T required for one rotation, M ≧ rp × T
A disc reproducing device characterized by being determined under the condition. 4. Digital data encoded from a disc in which spiral or concentric recording tracks are recorded so that encoded digital data including transmission rate information so as to match different transmission rates for each period. In a disc reproducing apparatus for reproducing the data, first storage means for temporarily storing the digital data read from the disc, control means for controlling writing of the digital data in the first storage means, Decoding means including second storage means for decoding, capable of extracting the transmission rate information from the digital data, third storage means attached to the decoding means, and the decoding means Control means for controlling the digital data to be read from the first storage means at a transmission rate according to the transmission rate information. Disc reproducing apparatus according to claim. 5. The disc reproducing apparatus according to claim 4, wherein the first storage means is also used as the second storage means. 6. The method according to claim 4, wherein the first storage means and the second storage means are the third storage means.
A disk reproducing device characterized in that it is also used as the storage means. 7. A digital data encoded from a disc in which spiral or concentric circular recording tracks are recorded so that encoded digital data including transmission rate information so as to match a different transmission rate for each period. In the disc reproducing apparatus for reproducing the data, storage means for temporarily storing the digital data read from the disc, control means for controlling writing of the digital data in the storage means, Decoding means capable of extracting the transmission rate information from the digital data, and control means for controlling the decoding means to read the digital data from the storage means at the transmission rate according to the transmission rate information during normal reproduction. During variable speed reproduction, the desired digital data is read from the digital data read from the disc. Retrieve the data, the disk reproducing apparatus comprising: a search means for outputting to the decoding means. 8. A disc in which digital data encoded so as to include transmission rate information so as to be different for each period is recorded in spiral or concentric recording tracks at a constant linear velocity. In a disc reproducing apparatus provided with a rotating unit for rotating and a data reading unit for reading data from the disc, a storage unit for temporarily storing digital data read from the disc, and a digital unit for storing the digital data in the storage unit. Control means for controlling writing of data; decoding means for extracting the transmission rate information from the digital data during normal reproduction; and decoding means for decoding the transmission rate information from the storage means during normal reproduction. Control means for controlling the digital data to be read at a transmission rate according to When the storage amount detecting means detects that the data storage amount in the storage means is equal to or larger than the capacity, the writing control means writes the data to the storage means. The writing of digital data is stopped, and at the same time, the data reading means is moved inward by one recording track, and when the data reading means returns to the position before the movement, the digital data in the storage means is written. Control means for restarting writing and controlling the data reading means to move to a predetermined position during variable speed reproduction; and, during variable speed reproduction, the data reading means read from the disk. A disc reproducing apparatus comprising: a retrieval unit that retrieves desired digital data from digital data and outputs the retrieved digital data to the decoding unit. 9. The capacity M of the storage means according to claim 8, wherein the capacity M of the storage means is a transmission rate rp for reading the digital data from the disc, and the data reading means is on the recording track at the outermost periphery of the disc. A disc reproducing apparatus characterized by being determined under the condition of M ≧ rp × T by the time T required for one rotation. 10. The disc reproducing apparatus according to claim 8, wherein the retrieval unit retrieves digital data that can be decoded by itself among the digital data read from the disc. 11. The digital device according to claim 8, wherein the search means comprises at least one digital data that can be decoded by itself among the digital data read from the disc, and other digital data. A disk reproducing device characterized by searching a group of data. 12. A disc having spiral or concentric recording tracks on which digital data encoded so as to include transmission rate information so as to match different transmission rates for each period is recorded at a constant linear velocity. In a disc reproducing apparatus provided with a rotating unit for rotating and a data reading unit for reading data from the disc, a first storage unit for temporarily storing digital data read from the disc; Write control means for controlling writing of the digital data to the storage means, decoding means capable of extracting the transmission rate information from the digital data during normal reproduction, and decoding means during normal reproduction Control for reading the digital data from the first storage means at a transmission rate according to the transmission rate information And a storage amount detection unit for detecting the storage amount of the first storage unit, and the storage amount detection unit detects that the data storage amount in the first storage unit is equal to or larger than the capacity. In this case, the writing control means stops writing the digital data in the first storage means, and at the same time, moves the data reading means inward by one recording track, and the data reading means moves. At the time of returning to the previous position, the writing of the digital data to the first storage means is restarted, and at the time of variable speed reproduction, the data reading means is controlled to move to a predetermined position. Control means, search means for searching desired digital data from digital data read from the disk by the data reading means during variable speed reproduction, and search means by the search means Second storage means for temporarily storing the digital data, and control means for controlling to read the digital data from the second storage means in response to the variable speed reproduction request are provided. Disc player. 13. The capacity M of the first storage means according to claim 12, wherein a transmission rate rp for reading the digital data from the disc and a recording track on the outermost periphery of the disc by the data reading means. Depending on the time T required for one round at a certain time, M ≧ rp
A disc reproducing apparatus characterized by being determined under the condition of × T. 14. The retrieval device according to claim 12, wherein the retrieval unit is capable of decoding using digital data that can be decoded by itself among digital data read from the disc and one signal that has already been decoded. A disk reproducing device characterized by searching digital data. 15. Digital data encoded from a disc in which spiral or concentric recording tracks are recorded so that the encoded digital data including the information of the transmission rate is adapted to the different transmission rate for each period. In a disc reproducing apparatus for reproducing the data, first storage means for temporarily storing the digital data read from the disc, control means for controlling writing of the digital data in the first storage means, Decoding means including second storage means for decoding, capable of extracting the transmission rate information from the digital data during normal reproduction, and third storage means attached to the decoding means, During normal reproduction, the decoding means reads the digital data from the first storage means at a transmission rate according to the transmission rate information. And a search means for searching desired digital data from the digital data read from the disc during variable speed reproduction, and the digital data searched by the search means temporarily. Disk reproduction comprising a fourth storage means for storing and a control means for controlling the decoding means to read digital data from the fourth storage means in response to a request for variable speed reproduction. apparatus. 16. The disc reproducing apparatus according to claim 15, wherein the first storage means is also used as the second storage means. 17. The method according to claim 15, wherein the first storage means and the second storage means are the third storage means.
A disk reproducing device characterized in that it is also used as the storage means. 18. The disc reproducing apparatus according to claim 15, wherein the first storage means also serves as the fourth storage means. 19. The disk reproducing apparatus according to claim 15, wherein the second storage means also serves as the fourth storage means. 20. The first storage means, the second storage means, and the fourth storage means according to claim 15.
3. The disk reproducing apparatus, wherein the third storage means also serves as the storage means.