JP2001155395A - Digital signal reproducing method and reproducer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a digital signal reproducing method and a reproducer capable of performing tracking control surely at the time of reproducing a digital video signal with special reproductions, such as a variable speed reproduction and the like. SOLUTION: A digital video signal for special reproductions is recorded in the prescribed area on a recording medium by being divided into prescribed recording units while being added with prescribed information and when this recorded digitl video signal is reproduced, this reproducer performs tracking control by obtaining head traveling positional information from a reproduced signal. Track identification information capable of discriminating a track and track positional information capable of discriminating a position on the track are included in the prescribed information. The reproducer performs the track control by obtaining the tracking error information of a track unit from the track identification information and by obtainging the tracking error information of smaller than a track unit from the track positional information.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a digital signal reproducing method and a digital signal reproducing apparatus for reproducing a digital video signal in a special reproduction mode such as variable speed reproduction.

[0002]

2. Description of the Related Art As a technique for recording and reproducing a compressed digital signal, a digital signal recording apparatus is disclosed in Japanese Patent Laid-Open No. 8-27.
No. 3305. This digital signal recording device describes that a signal for variable speed reproduction is recorded. Further, Japanese Patent Application Laid-Open No. 8-96451 discloses a tracking control device which performs tracking control by calculating a tracking error from a reproduced signal.

[0003]

SUMMARY OF THE INVENTION The aforementioned Japanese Patent Application Laid-Open No. 8-27 is disclosed.
No. 3305 describes that data for variable speed reproduction is recorded, but there is insufficient consideration for tracking at the time of reproduction and there is an inconvenience during variable speed reproduction.

Japanese Patent Laid-Open Publication No. Hei 8-96451 describes that a tracking error is calculated using a reproduction signal. However, there is no consideration for a data error at the time of reproduction, and scanning position information is calculated from the reproduction signal. There was a problem with the feasibility of extraction.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a digital signal reproducing method capable of performing tracking control with high precision and capable of excellent variable speed reproduction when reproducing a digital video signal containing digital compressed information in a special reproduction mode such as variable speed reproduction. An object of the present invention is to realize a digital signal reproducing apparatus.

[0006]

In order to achieve the above object, a digital signal reproducing method and a reproducing apparatus according to the present invention comprise the following means. The second digital video signal used in a reproduction mode such as variable speed reproduction different from normal reproduction is divided into predetermined recording units in a predetermined recording area on a recording medium and recorded with predetermined information added thereto. When reproducing the second digital video signal, head scanning position information is obtained from the reproduced signal, and tracking control is performed.

[0007] The predetermined information added at the time of recording includes:
At least track identification information capable of identifying a track;
Track position information capable of identifying a position on a track is included, and the head scanning position information is obtained from the track identification information and the track position information of a reproduction signal.

[0008] The predetermined information added at the time of recording further includes a predetermined synchronization signal, the track identification information, and a first error correction code for the track position information. At least when the synchronization signal can be detected and the operation result of the first error correction code is error-free or error-correctable, it is obtained from the track identification information and the track position information.

In the tracking control, the head scanning position information is compared with position information set in advance to record the second digital video signal in a predetermined recording area. Tracking error information is obtained in units of tracking error information, and tracking error information of less than a track unit is obtained from the track position information to perform tracking control.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing a configuration example of a digital signal recording / reproducing apparatus according to the present invention.

In FIG. 1, 1 is an input / output terminal for digital signals, 5 is an input / output circuit for inputting digital signals or outputting reproduced signals, 10 is a data generating circuit for recording digital signals, and 15 is a data generating circuit for recording digital signals. A digital recording signal processing circuit for generating a recording signal of the digital signal, a digital reproduction signal processing circuit 20 for demodulating a reproduction signal at the time of digital signal reproduction, a data selection circuit 25 for selecting data at the time of digital signal reproduction, and 30a and 30b A rotary head, 40 a capstan, 45 a tape, 50 a control circuit for controlling a recording / reproducing mode and the like, 60 a timing at the time of recording, a timing generating circuit for generating a reference signal such as rotation of the rotary heads 30a and 30b, 65 is an oscillation circuit for generating a reference clock, 70 is a feed of the rotary heads 30a, 30b and the tape 45. A servo circuit for controlling the degree, 80 a recording and reproducing circuit of the analog video signal, 85 denotes an input terminal of the analog video signal, 86 is an output terminal of the analog video signal.

The input from the digital signal input / output terminal 1 is, for example, a digital broadcast signal. FIG. 2 shows an example of connection between a digital broadcast receiver and a digital signal recording / reproducing apparatus as an example. 2, reference numeral 100 denotes the digital signal recording / reproducing apparatus shown in FIG. 1, 110 denotes a digital broadcast receiver, 112 denotes a tuner, 114 denotes a selection circuit, 116 denotes a decoding circuit, 118 denotes an input / output circuit, and 120
Is a receiver, and 130 is an antenna.

A digital broadcast signal is obtained by converting a digitally compressed video signal subjected to digital compression processing into a packet format,
Data for a plurality of channels is transmitted in a time-division multiplexed form. In the digital broadcast receiver 110, first, the signal received by the antenna 130 is demodulated by the tuner 112. From the demodulated signal, a required digital compressed video signal is selected by the selection circuit 114, and if the signal is encrypted, processing such as decryption is performed as necessary.
The signal selected by the selection circuit 114 is decoded into a normal video signal by the decoding circuit 116 and output to the receiver 120. When recording, the signal selected by the selection circuit 114 is transmitted from the input / output circuit 118 to the digital signal recording / reproducing apparatus 1.
Output to 00. Digital signal recording / reproducing apparatus 100
In this case, a signal input via the digital signal input / output terminal 1 is recorded. On the other hand, the digital compressed video signal reproduced by the digital signal recording / reproducing apparatus 100 is output from the digital signal input / output terminal 1 and is decoded via the input / output circuit 118 of the digital broadcast receiver 110.
Sent to The decoding circuit 116 decodes the signal into a normal video signal and outputs it to the receiver 120 in the same manner as at the time of reception.

The circuit operation of the digital signal recording / reproducing apparatus 100 during recording / reproduction will be described. First, when recording,
The packet format digital compressed video signal input from the digital signal input / output terminal 1 is sent to the input / output circuit 5. Part of the packet data is sent to the control circuit 50 via the input / output circuit 5. The control circuit 50 detects the type of data or the like based on the information added to the packet data or the information sent separately, determines the recording mode based on the detection result, and determines the operation mode of the recording signal processing circuit 15 and the servo circuit 70. Set. Also, the input / output circuit 5
The packet data to be recorded in the data generation circuit 10 is output. The data generation circuit 10 generates data for variable speed reproduction, and outputs the generated data to the recording signal processing circuit 15 together with the packet data to be recorded. The recording signal processing circuit 15 generates and adds an error correction code, ID information, a subcode, and the like according to the operation mode set by the control circuit 50, outputs a recording signal, and outputs the recording signal via the rotary heads 30a and 30b. Tape 4
Record in 5.

At the time of reproduction, first, a reproduction operation is performed in an arbitrary reproduction mode, and the reproduction signal processing circuit 20 adds the I signal added at the time of recording.
D information, subcode, etc. are detected. From the information, the control circuit 50 determines the mode at the time of recording, and the reproduction signal processing circuit 2
0, reproduction is performed by resetting the operation mode of the servo circuit 70. In the reproduction signal processing circuit 20, the rotating heads 30a, 3a
After processing such as synchronization detection and error detection and correction is performed on the signal reproduced at 0b, the signal is output to the data selection circuit 25. Further, necessary information is extracted from the signal added at the time of recording and output to the control circuit 50. The data selection circuit 25 selects data recorded in a normal recording area during normal reproduction, and selects data for variable speed during variable speed reproduction, and outputs the selected data to the input / output circuit 5. The input / output circuit 5 outputs reproduced data from the digital input / output terminal 1 based on the timing signal generated by the timing generation circuit 60.

The timing generation circuit 60 controls the operation timing of the digital signal recording / reproducing apparatus on the basis of the rate of packet data input from the digital input / output terminal 1 during recording, and the clock supplied from the oscillation circuit 65 during reproduction. Is used to control the operation timing.

When recording / reproducing an analog video signal, the analog video signal input terminal 85 is used during recording.
The input signal is subjected to predetermined processing by an analog video signal recording / reproducing circuit 80 and recorded on the tape 45 by the rotary heads 30a and 30b.
The video signal reproduced by a and 30b is subjected to predetermined processing by an analog video signal recording / reproducing circuit 80 and then output from an analog video signal output terminal 86. In this case, although not shown, the servo circuit 70 is controlled based on the frame period of the analog video signal. Note that the head for analog recording may be shared with the head for digital recording, or may be provided independently.

Next, the digital compressed video signal will be briefly described with reference to FIG. As an example, in this embodiment, the digital compression method is MPEG2 which is an international standard.
(Moving Picture Experts Group 2) FIG. 3 is a diagram showing the relationship between intra-frame data compressed in units of frames of a digital compressed video signal and inter-frame data obtained by compressing only difference information using prediction from data of preceding and succeeding frames. . Three
01 is an intra frame, and 302 is an inter frame. The digital compressed video signal has a predetermined number of frames,
For example, 15 frames are set as one sequence, the beginning of the sequence is an intra frame, and the remaining frames are inter frames compressed using prediction from the intra frame. Of course, an intra frame may be arranged in addition to the head. An intra frame can be decoded from data of a single frame. However, in the case of an inter frame, it cannot be decoded without preceding, following, or preceding and following frame data.

FIG. 4 shows the structure of a digital compressed video signal. Reference numeral 303 denotes a picture header added in frame units, and 304 denotes a sequence header added in sequence units. The sequence header 304 includes a synchronization signal and information such as a transmission rate. The picture header 303 is composed of a synchronization signal, identification information of an intra frame or an inter frame, and the like. Normally, the length of each data changes depending on the amount of information. Therefore, at the time of transmission, it is divided into fixed-length packets and transmitted for easy transmission.

FIG. 5 shows the structure of a packet. The size of the packet is a fixed length, for example, 188 bytes. 30
6 is a packet header, and 307 is packet information. The digital compressed video signal of FIG. 4 is arranged in a packet information area. The packet header 307 includes information such as the type of packet information and where the packet information starts in the packet. Normally, there is no correlation between the size of the packet information 307 and the length of the digital compressed video signal in FIG. 4, and it is not particularly determined where the header such as the sequence header 304 is located in the packet information 307.

FIG. 6A shows an example of the configuration of a digital broadcast signal. Reference numeral 601 denotes the packet of FIG. Usually, an audio signal, information about a program, and the like are added to the compressed video signal, and a program of a plurality of channels is transmitted in a time-division multiplexed manner. FIG. 6A shows an example in which programs of three channels are multiplexed. V1, A1, and P1 are video signals and audio signals of the first channel, program information, V2, A2, and P2 are video signals of the second channel. The audio signal, program information, V3, A3, and P3 are the video signal, audio signal, and program information of the third channel.
Of course, the number of multiplexed channels other than 3
For example, four channels may be used, or other information may be multiplexed.

FIG. 6B shows a case where only the information of the first channel is selected from FIG. 6A. When recording the first channel, this information is output from the digital broadcast receiver 110 to the digital signal recording / reproducing apparatus 100 as recording packet data. Of course, other information may be included and recorded, and in order to facilitate the processing at the time of reproduction, a part of the packet header information or the like may be changed and then output.

FIG. 7 is a flowchart for generating variable speed reproduction data from the recording packet data of FIG. 6B. Since the variable speed reproduction data needs to be able to be decoded independently, it needs to be intra-frame data. Therefore, by extracting intra-frame data in packet units, it is possible to easily generate variable-speed reproduction data.

First, the packet header of the input packet is checked, and only the packet of the video signal is selected. Then, the packet information of the selected packet is confirmed, and a packet having a sequence header is detected. Then, from this packet to the packet having the second picture header is extracted as variable speed reproduction data. The last two
For a packet having a second picture header, a malfunction during decoding can be prevented by replacing data subsequent to the second picture header with dummy data. Further, in order to simplify the processing, up to the packet before the packet having the last second picture header may be extracted.

Since an intra frame is usually provided after the sequence header, the processing can be facilitated by setting the head of the variable speed reproduction data to the sequence header. In addition, in a typical decoding circuit, decoding is often performed based on a sequence header, and decoding can be facilitated by including a sequence header. When the decoding circuit is performing decoding based on the picture header, the head of the variable speed reproduction data may be used as the picture header. In this case, the information of the picture header can be detected to select the intra frame.

The extracted intra-frame data may not be used as it is as variable-speed reproduction data, but may be reconstructed by performing processing such as lowering the resolution. This makes it possible to reduce the amount of variable speed reproduction data.

Next, a recording method on the tape 45 will be described.

FIG. 8 shows a recording pattern of one track. In FIG. 8, reference numeral 803 denotes a subcode recording area for recording subcodes such as time information and program information;
07 is a data recording area for recording a digital compressed video signal, 802 and 806 are preambles of the respective recording areas, 804 and 808 are postambles of the respective recording areas, 805 is a gap between the respective recording areas, 801 and 809. Is the margin at the track end.
By providing a postamble, a preamble, and a gap in each recording area in this way, it is possible to perform dubbing on each area independently. Of course, a digital signal other than the digital compressed video signal may be recorded in the recording area 807.

FIG. 9 shows a block configuration of each area. FIG.
(A) is a block configuration of the data recording area 807. 920 is a synchronization signal, 921 is ID information, 922 is data, and 923 is a parity (C1 parity) for the first error detection and correction. For example, the synchronization signal 920 is 2
Byte, ID information 921 is 3 bytes, data 922 is 9
The 9 bytes and the parity 923 are composed of 8 bytes, and one block is composed of 112 bytes. FIG.
(B) is a block configuration of the subcode recording area 803. In the block of the subcode recording area, the synchronization signal 9
20 and the ID information 921 are the same as those in FIG. 9A, the data 922 is composed of 19 bytes, the parity 923 is composed of 4 bytes, and one block is one of the blocks in FIG. 9A.
/ 4 of 28 bytes. In this way, the number of bytes in one block is also set to an integer ratio, and the configuration of the synchronization signal 920 and the ID information 921 is the same in all areas, so that the block generation at the time of recording and the synchronization signal at the time of recording are performed. , ID information detection and the like can be processed by the same circuit. Of course, the configuration of the synchronization signal and the ID information may be changed for each recording area.

FIG. 10 shows the structure of the ID information 921.
1031 is a group number; 1032 is a track address; 1033 is a block address in one track;
35 is a group number 1031 and a track address 103
2 and a parity for detecting an error in the block address 1033. The block address 1033 is an address for identifying a block in each recording area. For example, 0 to 335 in the data recording area 807 and 0 to 15 in the subcode recording area 812. The track address 1032 is an address for identifying a track. For example, by changing the address in units of one track or two tracks and setting it to 0 to 5 or 0 to 2, 6 tracks can be identified. . For example, by changing the group number 1031 in units of six tracks identified by the track address 1032 and setting it as 0 to 15, 96 tracks can be identified by both addresses. By synchronizing the track address with a cycle of a second error correction code described later, processing at the time of recording and identification at the time of reproduction can be facilitated.

FIG. 11 shows the data structure of one track in the data recording area 807. The synchronization signal 92
0 and ID information 921 are omitted. The data recording area 807 is composed of, for example, 336 blocks.
A second error correction code (C2 parity) 11 in block 0
Record 43.

The C2 parity 1143 is, for example, 306 blocks × 6 tracks of data in units of 6 tracks.
It divides into eight, and adds C2 parity of 10 blocks to each of the 102 blocks. For example, a Reed-Solomon code may be used as the error correction code.

Each block of 99-byte data is composed of a 3-byte header 1144 and 96-byte data 1141.

FIG. 12 shows the structure of the header 1144 of the data recording area 807. The header 1144 includes format information 1231, block information 1232, and additional information 1
233. Format information 1231
Is information on a recording format, for example, 12
One piece of information is composed of 6 bytes of the block. By multiplex-recording this information a plurality of times, the detection capability at the time of reproduction is improved. The additional information 1233 constitutes one piece of information with, for example, 6 bytes of 6 blocks,
Various types of data can be recorded by setting the first byte as an item code indicating the type of information and the remaining 5 bytes as data. For example, information such as the recording time and the type of the recording signal are recorded. Here, detailed information on the variable speed reproduction data may be recorded.

FIG. 13 shows a digital compressed video signal transmitted in a packet format of 188 bytes in a data recording area 1.
14 shows an example of the configuration of a block when recording is performed on the recording medium 141. In this case, 4-byte time information 1325 is added and 192
One packet is recorded in an area of two blocks.

FIG. 14 shows that the length of the packet 601 is 140
This is the block configuration when it is set to bytes. At this time,
Two packets 601 are recorded in an area for three blocks.

FIG. 15 shows another example of the configuration of the packet shown in FIG. 13 or FIG. The packet includes, for example, 3-byte time information 1325, control information 1572 related to a 1-byte packet, and packet data 1371 of 188 bytes or 140 bytes. If the number of packet data 1371 is smaller than this, for example, 13
In the case of 0 bytes, dummy data may be added and recorded, or the area of control information may be increased.

The control signal 1572, for example, records information for identifying the break of one frame (picture) at the time of variable speed reproduction data.
Processing such as rearranging and outputting the order of the reproduced one-frame signal at the time of reverse reproduction becomes easy.

The time information 1325 is information on the time at which the packet was transmitted. That is, the time when a packet (the head) is transmitted or the interval between packets is counted by a reference clock, the count value is recorded together with the packet data, and the interval between the packets is determined based on the information at the time of reproduction. , The data can be output in the same form as when it was transmitted.

As described above, the ratio of the number of bytes of one packet to the number of bytes of the recording area of one block is a simple integer ratio n: m.
If m packets are recorded in n blocks, efficient recording can be performed even when the packet length is different from the recording area of one block. The variable speed reproduction data may have the same configuration.

FIG. 16 shows the structure of the block information 1232. The block information 1232 is information for identifying data in block units. Data information 1674
Is information for identifying the type of data recorded in this block. For example, 0 is set for a block where normal packet data is recorded, 1 is set for a block where valid data is not recorded, 2 is set for a block where first variable speed reproduction data is recorded, and 2nd variable speed reproduction is performed. For a block in which application data is recorded, the value may be set to 3. The block number 1675 is information for identifying the order of blocks when packet data is recorded in units of two blocks or three blocks. For example, 0 to 1 when recording in units of 2 blocks, 0 when recording in units of 3 blocks
To 2. The variable speed data information 1676 is information for identifying the data order of the variable speed reproduction data. For example, when the data for variable speed reproduction reproduced by one scan is 56
In the case of a block, a trick play address from 0 to 55 may be added to each block so that the order of the 56 blocks can be identified. Furthermore, the error correction code for variable speed reproduction data is
For example, when it is added in units of 112 blocks, address information that changes in 112 block periods may be added so that it can be identified. If this address is added, the data can be rearranged by the address at the time of reproduction, without recording in the order of reproduction. The error correction code for variable speed playback data is
Same as C2 parity, ie, 10 in 102 blocks
What is necessary is just to add the parity of the block. In particular, if the number of parities is made the same, the error correction processing can be made the same as during normal reproduction. FIG. 17 shows an example of the arrangement of the first variable speed reproduction data. Reference numeral 1711 denotes first variable speed reproduction data. The variable speed reproduction data is multiplex-recorded at a predetermined location on a track over the same track over several tracks. In this arrangement, all data can be detected regardless of the trajectory of the head during variable speed reproduction (see FIG. 17 head trajectories a and b). The data to be multiplexed is
By setting the variable speed data information 1676 to be the same, the order of data can be identified at the time of reproduction. The number of times of multiplexing may be determined according to the set speed of the variable speed reproduction.

FIG. 18 shows an example of the arrangement of the second variable speed reproduction data. Reference numeral 1812 denotes second variable speed reproduction data. In this way, by arranging only in the area corresponding to the scanning locus of the head at the time of variable speed reproduction, the area where variable speed reproduction data is recorded can be suppressed. Also in this case, the variable speed reproduction data 1812 is multiplex-recorded,
Reliability at the time of variable speed reproduction can be improved. However, in this arrangement method, it is necessary to perform tracking control in order for the head to correctly scan the area where the variable speed reproduction data is arranged. That is, in the example of the arrangement of the second variable speed reproduction data shown in FIG. 18, the head locus a can reproduce the variable speed reproduction data, but the head locus b cannot reproduce at all. Further, since the scanning locus of the head differs depending on the variable speed reproduction speed, it is necessary to change the area to be arranged according to each variable speed reproduction speed.

Next, the tracking control will be described. FIG. 19 shows the procedure of tracking control. In the tracking control, scanning position information is extracted from the reproduction signal, a tracking error is calculated, and control based on the tracking error is repeatedly performed.

FIG. 20A shows a head scanning locus on the tape at the time of variable speed reproduction, and FIG. 20B is a waveform diagram of the variable speed reproduction signal at that time, where the amplitude represents the reproduction level.
At the time of variable speed reproduction, scanning is performed across the track, so that the obtained reproduction signal becomes bursty. Whether or not the reproduction has been performed is determined by checking the result of synchronization detection and parity calculation of the reproduction signal.

The scanning position information can be obtained from, for example, ID information 921 of the reproduced signal. That is, the above-mentioned ID
In the example of the information 921, it is possible to identify 96 tracks by the group number 1031 and the track address 1032. Further, the block position on one track can be detected from the block address 1033.

FIG. 21 is a flowchart for extracting scanning position information during variable speed reproduction. Basically, in the variable speed reproduction, the scanning position information is extracted from the ID information 921 of the block being reproduced.

First, the synchronization signal 920 is detected. If the synchronization signal cannot be detected, it is determined that the block has not been reproduced. After detecting the synchronization signal 920, the ID
The parity 1035 of the information 921 is checked. If an error is detected in the operation of the parity 1035, the ID information 9
Since the content of 21 is not reliable, it is considered that the block has not been reproduced. The ID information 921 includes the synchronization signal 92
It is valid when 0 is detected and there is no error in the operation of the parity 1035.

Further, if the data 922 cannot be reproduced, data for variable speed reproduction cannot be obtained, so that the operation result of the parity 923 added to the data 922 is also used.
If an error can be corrected by the operation result of the parity 923, the data 922 of the block can be regarded as valid.

Therefore, the synchronization signal 920 can be detected,
If the operation result of the parity 1035 is error-free and the operation result of the parity 923 is correctable, it is determined that the block can be reproduced, and the ID information 9 of the block is determined.
21 is extracted as scanning position information.

As described above, if at least the synchronization signal 920 can be detected and the operation result of the parity 1035 has no error, it can be determined that the ID information 921 is valid. Therefore, if the operation result of the parity 923 is not used, the synchronization signal 920 can be detected, and the operation result of the parity 1035 is error-free, the ID information 921 may be used as the scanning position information.

In the above description, the parity 1035 is used only for detecting an error, but there is no problem even if error correction is performed depending on the added parity. In that case,
The parity 1035 may be determined to be valid if there is no error or the error can be corrected in the operation result of the parity 1035.

The signal processing described above is performed by the digital reproduction signal processing circuit 20, and the obtained scanning position information is processed by the control circuit 50. FIG. 22 shows a configuration example of the reproduction signal processing circuit 20 that performs the above-described signal processing. 22, reference numeral 2601 denotes an input terminal of a signal reproduced by the rotary heads 30a and 30b; 2605, a synchronization detection circuit; 2610, an ID information processing circuit for processing ID information added at the time of recording;
2615, a first error correction circuit for processing a C1 parity 923; 2620, an information extraction circuit for extracting scanning position information; 2625, a second error correction circuit for processing a C2 parity 1143; An output terminal for outputting data to the data selection circuit 25 and an input / output terminal 2635 for inputting / outputting information from / to the control circuit 50 are provided.

First, the operation during normal reproduction will be described.
The operation mode and the like of the reproduction signal processing circuit 20 are set by the control circuit 50 via the input / output terminal 2635. A signal reproduced by the rotary heads 30a and 30b is supplied to an input terminal 260.
1 to the synchronization detection circuit 2605. In the synchronization detection circuit 2605, the synchronization signal 920 added at the time of recording is
And outputs a detection signal. ID information processing circuit 26
10 performs processing of the ID information 921 added at the time of recording. That is, in this embodiment, an error is detected based on the parity 1035 added at the time of recording, and the group number 1031, track address 1032, block address 1033, and the like are detected. Next, the first error correction circuit 2615 calculates a C1 parity 923 added to the data 922 at the time of recording, and performs a first error correction process. The signal subjected to the first error correction processing is sent to a second error correction circuit 2625. In this embodiment, the C2 parity 1143 is added in units of six tracks. Therefore, after storing the data for six tracks in, for example, a memory or the like, the C2 parity operation is performed,
And outputs the result. The signal subjected to the second error correction processing is output to data selection circuit 25 via output terminal 2630. During normal reproduction, the information extraction circuit 2620 does not need to operate.

Next, signal processing at the time of variable speed reproduction will be described. First, the control circuit 50 causes the input / output terminal 2635
, The operation mode of the reproduction signal processing circuit 20 and the like are set. The signals reproduced by the rotary heads 30a and 30b are input to the reproduction signal processing circuit 20 via the input terminal 2601. Sync detection circuit 2605, ID information processing circuit 261
0, the operation and signal processing of the first error correction circuit 2615 are basically the same as during normal reproduction.

The information extraction circuit 2620 performs synchronization detection, ID
Information processing and the result of the C1 parity operation are received. As described above, the synchronization signal 920 can be detected and the parity 1
If the operation result of 035 is error-free and the operation result of parity 923 can be corrected, the ID information 921 is extracted as scanning position information and output to the control circuit 50 via the input / output terminal 2635. The extracted scanning position information may be temporarily stored in a memory or the like and then output to the control circuit 50.

As described above, if at least the synchronization signal 920 can be detected and the operation result of the parity 1035 has no error, it can be determined that the ID information 921 is valid. Therefore, if the operation result of the parity 923 is not used, the synchronization signal 920 can be detected, and the operation result of the parity 1035 is error-free, the ID information 921 may be used as the scanning position information.

In the above description, the parity 1035 is used only for detecting an error. However, there is no problem even if error correction is performed depending on the added parity. In that case,
With respect to the parity 1035 in the ID information processing result, it can be determined that the parity 1035 is valid if there is no error or the error can be corrected in the operation of the parity 1035.

The signal subjected to the first error correction processing is sent to a second error correction circuit 2625. Here, when the error correction code is added for the variable speed reproduction data in a fixed block unit as described above, the error correction processing is performed, and then the data is output to the data selection circuit 25 via the output terminal 2630. I do.

With the circuit configuration as described above, reproduction signal processing including scanning position information extraction at the time of variable speed reproduction can be realized. In this embodiment, the scanning position information is extracted by a circuit, but the present invention is not limited to this.
For example, a method may be used in which a reproduced signal is written in a memory, data is read out by the control circuit 50, and the above-described operation such as parity is performed.

The control circuit 50 calculates a tracking error from the scanning position information. The tracking error can be obtained by comparing the scanning position information obtained from the reproduction signal with the recording position information of the reference variable speed reproduction data.

FIG. 23 shows an example of the arrangement of the second variable speed reproduction data shown in FIG. 18, and shows an example of the arrangement of the variable speed reproduction data at the time of 6 × speed reproduction. In FIG. 23, areas a1 to a4 are recording areas for variable speed reproduction data. If the tracking control is performed accurately, the head scanning trajectory at the time of 6 × speed reproduction is the head scanning trajectory h1 in FIG.
It becomes as shown in. The variable speed reproduction data can be obtained by scanning the recording areas a1 to a4 of the variable speed reproduction data by the head. On the other hand, the head scanning locus h2 in FIG.
Is an example of a head trajectory at the time of 6 × speed reproduction with tracking deviated. The areas b1 to b4 are areas that can be reproduced with the head locus h2, and the variable speed reproduction data cannot be reproduced.

FIG. 24A shows variable-speed playback data recording position information indicating areas a1 to a4 by group number, track address and block address, respectively.
Here, the head block address of each area is a1
s, a2s, a3s, a4s, and the last block address of each area are represented by a1e, a2e, a3e, and a4e, respectively. This is the reference data for tracking error calculation.

FIG. 24B shows the scanning position information for the areas b1 to b4, ie, the group number, the track address and the block address, which are extracted when the reproduction is performed on the head locus h2. Here, the head block addresses of the respective areas are respectively represented by b1s, b2s, b3s, b4s,
The tail block address of each area is represented by b1e and b2, respectively.
e, b3e, and b4e.

The error per track can be calculated by comparing the recording position information with the group number and the track address of the scanning position information. For example, comparing with the example of FIG.
It can be seen that the scanning position is shifted by +2 tracks with respect to the recording position. Thereby, the error per track can be controlled.

Further, the regions a1 and b in the example of FIG.
1, block addresses are used to eliminate the block address shift of a2 and b2, a3 and b3, and a4 and b4, that is, the shift of each area. Hereinafter, FIG.
An example of the method will be described with reference to FIG. FIG. 25A illustrates the amount of deviation between the recording area a1 and the reproduction area b1. The calculation of the tracking error trk shown in FIG. 25A is performed in the following procedure. The block addresses a1m and b1m at the midpoint between the reference and the reproduction area are used. The midpoint a1m is
a1m = (a1e−a1s) / 2, and the middle point b1m
Is represented by b1m = (b1e−b1s) / 2. The block error blk can be obtained by blk = b1m-a1m. Further, a tracking error trk is calculated from the block error blk.

The shift amount bre of the block address when the tracking is shifted by one track shown in FIG.
f is bref = M / (N−N) where N is the variable speed reproduction speed and M is the number of blocks per track.
It is represented by 1). The tracking error trk can be calculated from the ratio between the block errors blk and bref.
= Blk / bref = blk * (N-1) / M.

In the above example, the case where recording was performed at a fixed tape speed was described. However, when a plurality of recording modes having different tape speeds, such as a long-time recording mode, are provided, the tracking error is calculated according to the same principle. Is possible.

As described above, the tracking error can be obtained from the group number, track address, and block address obtained as the scanning position information. The above calculation is performed by the control circuit 50. The control circuit 50 has the recording position information of the variable speed reproduction data serving as a reference, and calculates a tracking error from the value and the scanning position information.
The configuration in which the above-described calculation is performed by the control circuit 50 such as a microprocessor has an advantage that even when a format for variable speed playback is added or changed, the format can be flexibly handled by changing software.

The calculated error information is sent to the servo circuit 70. The servo circuit 70 performs tracking control based on the error information. Thereby, even in the arrangement of the second variable speed reproduction data as shown in FIG. 18, the scanning position can be extracted from the reproduction signal and tracking control can be applied, and the variable speed reproduction data can be surely reproduced. be able to.

When variable speed reproduction data is multiplex-recorded, the same data may be reproduced a plurality of times. In the present invention, the more reliable data is used by using the operation result of the parity 923. FIG. 26 is a diagram showing a processing flow of the selection circuit 25 at the time of variable speed reproduction. From the reproduction signal processing circuit 20, the calculation result of the parity 923 is input to the data selection circuit 25 together with the signal on which the error detection and correction have been performed. In the example of the present invention, the parity 92
Since 3 is 8 bytes, up to 4 symbol corrections are possible.
Therefore, as an operation result of the parity 923, 0: no error, 1: 1 symbol correction, 2: 2 symbol correction, 3: 3
Data such as symbol correction, 4: 4 symbol correction, and 5: uncorrectable are multiplexed and output at the head of each block.
The data selection circuit 25 stores only the data for variable speed reproduction obtained by one head scan together with the operation result of the parity 923 in a memory or the like. The address to be written to the memory may correspond to the trick play address of the variable speed data information 1676. In the case of multiplexed recording, variable speed reproduction data having the same variable speed data information 1676 is reproduced a plurality of times, so that the result of calculation of the parity 923 of the same variable speed reproduction data is read before writing to a memory or the like. . If the number of error corrections is smaller than the read operation result, writing is performed on the memory, and if the number of error corrections is higher, writing is not performed. As a result, more reliable variable speed reproduction data always remains on the memory.

As described above, in the present invention, tracking control is performed by extracting information on the head scanning position from the reproduced signal. Therefore, at the time of variable speed reproduction, data for variable speed reproduction can be reproduced more accurately,
Good variable speed reproduction can be realized.

[0073]

According to the present invention, when a digital video signal is reproduced from a recording medium in a special reproduction mode such as variable speed reproduction, information on a head scanning position is extracted from the reproduction signal to perform tracking control. did. As a result, a reproduction method and a reproduction apparatus capable of performing high-accuracy tracking control even in the special reproduction mode and reliably reproducing the data for special reproduction are provided.

[Brief description of the drawings]

FIG. 1 is a block diagram showing one embodiment of the present invention.

FIG. 2 is a connection diagram of a digital signal recording / reproducing device and a digital broadcast receiver.

FIG. 3 is a diagram illustrating a relationship between intra-frame data and inter-frame data of a digital compressed video signal.

FIG. 4 is a configuration diagram of a digital compressed video signal.

FIG. 5 is a configuration diagram of a packet.

FIG. 6 is a configuration diagram of a digital broadcast signal.

FIG. 7 is a diagram showing a flow for generating variable speed reproduction data.

FIG. 8 is a diagram showing a recording pattern of one track.

FIG. 9 is a configuration diagram of a block.

FIG. 10 is a configuration diagram of ID information.

FIG. 11 is a configuration diagram of data of one track.

FIG. 12 is a configuration diagram of a header of a data recording area.

FIG. 13 is a diagram illustrating a configuration example of a block.

FIG. 14 is a diagram illustrating another configuration example of a block.

FIG. 15 is a diagram illustrating another configuration example of a packet.

FIG. 16 is a configuration diagram of block information.

FIG. 17 is a diagram showing an arrangement of first variable speed reproduction data.

FIG. 18 is a diagram showing an arrangement of second variable speed reproduction data.

FIG. 19 is a processing flow of tracking control.

FIG. 20 is a diagram illustrating a head locus and a reproduction signal waveform during variable speed reproduction.

FIG. 21 is an extraction flow of scanning position information.

FIG. 22 is a diagram illustrating a configuration example of a reproduction signal processing circuit 20;

FIG. 23 is a diagram illustrating an example of an arrangement of data for variable speed reproduction and a head trajectory during variable speed reproduction.

FIG. 24 is an example of scanning position information.

FIG. 25 is a diagram illustrating a method of calculating a tracking error.

FIG. 26 is a processing flow of the selection circuit 25 at the time of variable speed reproduction.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Digital signal input / output terminal, 10 ... Data generation circuit, 15 ... Digital recording signal processing circuit, 20 ... Digital reproduction signal processing circuit, 25 ... Data selection circuit, 50 ...
Control circuit 70 servo circuit 301 intra-frame compressed data 302 inter-frame compressed data
303: picture header, 304: sequence header,
306: packet header, 307: packet data, 8
03: Subcode recording area, 807: Data recording area,
920: synchronization signal, 921: ID information, 922: data, 923: C1 parity, 1031: group number,
1032: track address, 1033: block address, 1035: parity, 1144: header, 114
3 ... C2 parity, 1902 ... Head scanning position information extraction, 1903 ... Tracking error calculation, 1904 ... Tracking control, 2508 ... C1 parity comparison, 2605
... Synchronization detection circuit, 2610 ... ID information processing circuit, 261
5 first error correction circuit, 2620 information extraction circuit, 2
625: second error correction circuit, 2635 input / output terminal.

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Nobutaka Amada Inventor F-term in the Digital Media Development Division, Hitachi, Ltd. 292 Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa F-term (Reference) 5D097 AA02 BB06 BB09 CC05 EE02 FF01 FF15 HH06 LL02

Claims (10)

[Claims] A first digital video signal used in normal reproduction and a second digital video signal used in a reproduction mode different from normal reproduction are respectively recorded in a predetermined recording area on a recording medium in a predetermined recording unit. In a digital signal reproducing method for reproducing a signal recorded with predetermined information added thereto by a magnetic head, when reproducing the second digital video signal, head scanning position information is obtained from the reproduced signal. And a tracking control. 2. The second digital video signal is a signal used at the time of variable speed reproduction, and the second digital video signal is a second digital video signal on the recording medium.
2. The digital signal reproducing method according to claim 1, wherein the predetermined recording area of the digital video signal is determined based on a head scanning trajectory corresponding to a variable speed reproducing speed. 3. The predetermined information to be added at the time of recording includes at least track identification information capable of identifying a track and track position information capable of identifying a position on a track. 2. A digital signal reproducing method according to claim 1, wherein the digital signal is obtained from the track identification information and the track position information of a reproduction signal. 4. The information to be added at the time of recording further includes a predetermined synchronization signal, the track identification information, and a first error correction code for the track position information. Wherein at least the synchronizing signal can be detected and the operation result of the first error correction code is obtained from the track identification information and the track position information when no error or error correction is possible. 3. The digital signal reproducing method according to 3. 5. The tracking control according to claim 1, wherein the head scanning position information is compared with position information set in advance for recording the second digital video signal in a predetermined recording area, and the head scanning position information is compared with the track identification information. 4. The digital signal reproducing method according to claim 3, further comprising: obtaining tracking error information for each track, obtaining tracking error information for each track less than said track position information, and performing tracking control. 6. The predetermined information includes a second error correction code added for each of the predetermined recording units, and the second digital video signal is repeatedly recorded in the predetermined recording area. 2. The method according to claim 1, wherein when the second digital video signal repeatedly recorded is reproduced, a smaller one of the error correction locations is selected and output according to the operation result of the second error correction code. The digital signal reproducing method according to the above. 7. A first digital video signal used in normal reproduction and a second digital video signal used in a reproduction mode different from normal reproduction are respectively stored in a predetermined area on a recording medium in a predetermined recording unit. In a digital signal reproducing apparatus for reproducing a signal recorded by dividing and adding predetermined information with a magnetic head, a head scanning position information extracting means for extracting head scanning position information from a reproduced signal; and the extracted head scanning position Based on the information, a tracking error calculating means for calculating tracking error information, and a tracking control means for performing tracking control based on the tracking error information, when reproducing the second digital video signal, On the basis of the head scanning position information extracted by the head scanning position information extracting means, the A digital signal reproducing apparatus, wherein tracking control is performed by the tracking control means using racking error information. 8. The second digital video signal is a signal used at the time of variable speed reproduction, and the second digital video signal is a signal used for the second digital video signal on the recording medium.
8. The digital signal reproducing apparatus according to claim 7, wherein the predetermined recording area of the digital video signal is determined based on a head scanning trajectory corresponding to a variable speed reproducing speed. 9. The predetermined information added at the time of recording includes a predetermined synchronization signal, track identification information capable of identifying a track, track position information capable of identifying a position on a track,
And an error correction code for the track identification information and the track position information. The head scanning position information extraction means includes: synchronization detection means for detecting the synchronization signal; and the track identification information, the track position information; ID information processing means for processing the error correction code; and information extraction means for extracting head scanning position information based on the results of the synchronization detection means and the ID information processing means. When the synchronization detection means can detect a synchronization signal and the ID information processing means determines that the operation result of the error correction code is error-free or error-correctable, the track identification information and the track position information are stored in the head. 8. The digital signal reproducing apparatus according to claim 7, wherein the digital signal is extracted as scanning position information. 10. The predetermined information added at the time of recording includes:
The head scanning position information extracting means includes at least track identification information capable of identifying a track and track position information capable of identifying a position on the track. Extracting the head scanning position information; and the tracking error calculating means, in order to record the head scanning position information extracted by the head scanning position information extracting means and the second digital video signal in a predetermined recording area, in advance. 8. The method according to claim 7, further comprising obtaining tracking error information for each track from the track identification information, and obtaining tracking error information for less than a track unit from the track position information by comparing the set position information.
A digital signal reproducing apparatus according to claim 1.