JP3416562B2 - Special playback method in video recording and playback device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a trick play method in a video recording / playback apparatus.

[0002]

2. Description of the Related Art Video captured by a surveillance camera is
For example, a video recording / reproducing apparatus has been developed which compresses an image by a JPEG type image compression apparatus, records it on a video tape, reads data recorded on the video tape, expands it by an image compression apparatus, and outputs it. There is.

By the way, the present applicant has developed a video recording / reproducing apparatus capable of reducing the recording code amount. However, this is not a known technique. In the video recording / reproducing apparatus newly developed by the present applicant, at the time of recording, the input video data is the first basic video data at a predetermined number of field cycles.
The input video data is stored in the memory and compressed.

Regarding the input video data of each field between the field stored in the basic video storage memory and the field stored next in the basic video storage memory,
The difference from the basic image data stored in the basic image storage memory is taken, and the obtained difference data is compressed.

The compressed data of each field is
The data is recorded on a recording medium together with identification information indicating whether the data is for basic video data or difference data.

[0006]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a special reproduction method suitable for a video recording / reproducing apparatus newly developed by the present applicant, such as reverse reproduction, fast forward reproduction, fast reverse reproduction and the like. .

[0007]

In the special reproduction method in the first video recording / reproducing apparatus according to the present invention, at the time of recording, input video data is stored in the first memory as basic video data in a predetermined number of field cycles. compresses the input image data, among the input image data, the input image data of each field until the field stored in the next first memory from a field that will be stored in the first memory, the first memory Take the difference with the most recently stored basic video data, compress the obtained difference data,
This is a special reproduction method in a video recording / reproducing apparatus in which each compressed data is recorded on a recording medium together with identification information indicating whether the data is for basic video data or for differential data for each field. In some cases, data for multiple fields from the recording medium
Data is read in block units including data and stored alternately in two second memories for each block unit, and one block of data is stored each time one block of data is stored in the second memory. Data is read from the completed second memory, the read data is expanded in field units, and if the expanded data in field units is basic video data, the basic video data is stored in the first memory. When the decompressed field unit data is differential data, the original video data is restored based on the differential data and the basic video data most recently stored in the first memory. Then, the obtained video data is output as playback video data, and if a reverse playback command is input during normal playback, the A old direction of the recording time from the last read data in the second memory the data has been read for normal reproduction by normal reproducing operation until the first
Up to the data corresponding to the basic video data currently stored in the memory, reverse playback is performed by sequentially reading in the reverse direction, and when reverse playback is performed for older data thereafter, one basic video data and the basic video data For each data group corresponding to one or a plurality of difference data obtained by subtracting the difference from, the data for the basic video data is first decompressed and stored in the first memory, and then each data in the data group is reversed. It is characterized in that the reverse reproduction is performed by sequentially reading the data.

In the special reproduction method in the second video recording / reproducing apparatus according to the present invention, at the time of recording, the input video data is stored in the first memory as basic video data at a predetermined field number cycle and the input video data is compressed. and the input of the image data, the input image data of each field until the field stored in the next first memory from the off <br/> field that will be stored in the first memory, the latest in the first memory The difference with the basic video data stored in is taken, the obtained difference data is compressed, and each compressed data is
This is a special reproduction method in a video recording / reproducing apparatus in which each field is recorded on a recording medium together with identification information indicating whether the data is for basic video data or differential data. Data is read from the medium in block units including data for a plurality of fields and stored alternately in two second memories for each block unit, and one block of data is stored in the second memory. Each time, the compressed data corresponding to the basic video data is read out from the second memory, which has completed storing one block of data, in order from the oldest recording time to the newest, and the expanded video data is decompressed. It is characterized in that it is output as reproduced video data.

In the special reproduction method in the third video recording / reproducing apparatus according to the present invention, during recording, the input video data is stored in the first memory as basic video data in a predetermined number of field cycles and the input video data is compressed. and the input of the image data, the input image data of each field until the field stored in the next first memory from the off <br/> field that will be stored in the first memory, the latest in the first memory The difference with the basic video data stored in is taken, the obtained difference data is compressed, and each compressed data is
A special reproduction method in a video recording / reproducing apparatus for recording, for each field, on a recording medium together with identification information indicating whether the data is for basic video data or for differential data, and at the time of fast reverse reproduction, Data is read from the recording medium in block units containing data for a plurality of fields and in such a manner that the recording time goes to an old block, and the data is alternately stored in two second memories for each block unit. Every time one block of data is stored in the second memory, only the compressed data corresponding to the basic video data is recorded from the second memory, which has completed the storage of one block of data, in the order of recording time from oldest to oldest. It is characterized in that it is read and expanded, and the expanded video data is output as reproduced video data.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment in which the present invention is applied to a digital VTR for recording / reproducing an image picked up by a surveillance camera will be described below with reference to the drawings.

[1] Description of Overall Configuration of Monitoring System

FIG. 1 shows the overall structure of the monitoring system. The surveillance system includes a video camera (hereinafter referred to as a surveillance camera) 101 and a digital VT for compressing and recording a video signal obtained by the surveillance camera 101.
An R102 and a monitor 103 for displaying an image reproduced by the digital VTR 102 are provided.

[2] Description of the recording operation of the video signal processing circuit of the digital VTR 102

FIG. 2 shows the configuration of the video signal processing circuit of the digital VTR 102. The recording operation of the video signal processing circuit will be described.

At the time of recording, the analog video signal sent from the surveillance camera 101 is converted into digital video data by the decoder 11. The video data obtained by the decoder 11 is sent to the difference block 12. The difference block 12 includes a memory 31 and addition / subtraction means 32. The memory 31 is the first FPGA 1
3 (field programmable gate array).

FIG. 3 shows the operation of the differential block 12 during recording. In FIG. 3, numbers indicate feed numbers.

The first FPGA 13 stores the video data output from the decoder 11 in the memory 31 as basic video data in a predetermined field number cycle (6 vertical period cycles in this example), and at the same time, stores the video data. Is sent to the image compression / expansion circuit 14 through the addition / subtraction means 32.

The video data of each field between the field stored in the memory 31 and the field next stored in the memory 31 is sent to the addition / subtraction means 32 and is stored in the memory 31 as the basic video data. And the obtained difference data is sent to the image compression / decompression circuit 14.

In the example of FIG. 3, field numbers "1", "
Video data "1" and "7" of 7 "are stored in the memory 31 and sent to the image compression / expansion circuit 14. Video data" 2 "of each field between the field numbers" 1 "and" 7 ". "~" 6 "is sent to the addition / subtraction means 32,
The difference from the basic video data “1” stored in the memory 31 is taken, and the obtained difference data is sent to the image compression / expansion circuit 14. The video data (basic video data) that has passed through the addition / subtraction means 32 and is sent to the image compression / expansion circuit 14 is referred to as I video data. The data (difference data) sent to the circuit 14 will be referred to as P video data.

In the image compression / expansion circuit 14, the video data sent from the difference block 12 is compressed field by field by, for example, the JPEG system. The compressed video data (encoded data) obtained by the image compression / expansion circuit 16 is sent to the additional information addition / separation unit 15.

On the other hand, the microcomputer 40 acquires from the first FPGA 13 I / P identification information indicating whether the compressed video data sent to the additional information adding / separating unit 15 is for I video or P video. Then, it is sent to the additional information adding / separating unit 15 together with the recording time information (current year, month, day, minute, second).

In the additional information adding / separating unit 15, the compressed video data obtained by the image compression / expansion circuit 14 is added to the I / P identification information, recording time information, etc. corresponding to the compressed video data sent from the microcomputer 40. Is added. The data to which the predetermined data has been added by the additional information addition / separation unit 15 is sent to the second FPGA 16.

The second FPGA 16 stores the data sent from the additional information adding / separating unit 15 in two memories 1 for each predetermined block unit including data for a plurality of fields.
Each time data is written in 7 and 18 alternately, one block of data is written in the memory, and the data is read from the memory in which the writing of one block of data is completed and sent to the formatter 19. In this example, one block includes 288 tracks of data including information about audio.

That is, the second FPGA 16 writes the data sent from the additional information adding / separating unit 15 into one memory, for example, the first memory 17. When the writing of the data for one block to the first memory 17 is completed, the memory for writing the data is switched to the other second memory 18, and at the same time, the first memory 1
From 7, data reading is started.

The data read from the first memory 17 is sent to the formatter 19. Then, when the reading of the data for one block from the first memory 17 is completed, the reading is stopped.

After that, when the writing of the data for one block to the second memory 18 is completed, the memory for writing the data is switched to the first memory 17, and at the same time, the second memory is written.
Reading of data from the memory 18 is started. Second
The data read from the memory 18 is the formatter 1
Sent to 9. Then, when the reading of one block of data from the second memory 18 is completed, the reading is stopped. After that, similar processing is repeated.

The formatter 19 converts the sent data into data having a data structure which can be recorded on the video tape. The data obtained by the formatter 19 is recorded on the video tape via the recording amplifier and the video head in the signal recording / reproducing unit 20. That is, basically, video data is recorded on the video tape in units of one block (for 288 tracks). The video tape is stopped each time the recording of data in units of one block is completed.

The second FPGA 16 and the formatter 19 are controlled by the microcomputer 40.

FIG. 4 shows a format for data of one field recorded on the video tape.

The data block for one field comprises a header portion 51, an audio data portion 52 and a video data portion 53.

The header portion 51 includes additional information such as I / P identification information, recording time information (year, month, day, hour, minute, second), a quantization table (Q table), audio additional data and the like. Has been. As the I / P identification information, for example, "EX
FFh "is used and is inserted as a frame header at the beginning of the header portion 51. Here," EXFFh "
"H" in "EXFF" indicates that it is a hexadecimal number. If "X" in "EXFF" is 0, I video is displayed.
If X "is 1, it represents a P video. At the end of the video data section 53, an end code (EOI; for example," D9FFh ") indicating the end of the video data section is inserted.

[3] Description of Video Head Clogging Inspection Performed During Recording

As described above, at the time of recording, every time one block of data is written on the video tape,
The video tape is stopped, and the time during which the video tape is stopped is used to check the video head for clogging. Here, a case will be described in which two video heads are provided facing the rotating drum by 180 degrees.

As shown in FIG. 5, when one block of data (block0 data in FIG. 5) is recorded on the video tape, the dummy data is recorded for six tracks and then the video tape is stopped. . Then, in the stopped state, the clogging inspection of each video head is performed. When the clogging inspection is completed, the capstan is rotated in the reverse direction by a predetermined amount to prevent the damage of the video tape, so that the video tape is slightly loosened and made to stand by. After that, when the recording timing of the data of the next block (data of block1 in FIG. 5) comes, first, after recording the dummy data for a predetermined number of tracks, the recording of the data of the next block on the video tape is started. To be done.

The inspection for clogging of each video head is performed as follows. As shown in FIG. 6, recording / reproduction (REC & PLAY) of the test pattern is performed three times for each head while the video tape is stopped. The recording timing and the reproducing timing of the test pattern of each video head are controlled based on the switching pulse, as shown in FIG.

The microcomputer 40 calculates the sum of the head outputs at the time of reproducing three times for each video head, and if it is a predetermined value or less (for example, 1/4 or less of the normal value), the video head is selected. It is determined that clogging has occurred. When it is determined that the clogging has occurred in any of the video heads, the microcomputer 40 stops recording and notifies that effect.

[4] Description of operation during reproduction of video signal processing circuit

At the time of reproduction, the video head in the signal recording / reproducing section 20 reads data from the video tape in block units. The read video data is reproduced by the reproduction amplifier and formatter 1 in the signal recording / reproducing unit 20.
9 to the second FPGA 16.

The second FPGA 16 alternately writes the sent data to the two memories 17 and 18 for each block, and every time one block of data is written to the memory, one block of data is written. The data is read from the memory in which the writing of the data is completed and sent to the additional information adding / separating unit 15.

The second FPGA 16 has a formatter 19
When writing the data sent from the memory 17 or 18 into the memories 17 and 18, in order to recognize the write address of the data for each field unit, as shown in FIG. A subbank indicating the storage start address is created in the memory.

The additional information adding / separating unit 15 separates the additional information such as I / P identification information and time information from the sent data for one field. The separated data is sent to the first FPGA 13 via the microcomputer 40.

The data after the predetermined data is separated by the additional information adding / separating unit 15 is the image compression / expansion circuit 1.
4 and is expanded for each field. The video data obtained by the image compression / expansion circuit 14 is sent to the difference block 12.

FIG. 8 shows the operation of the difference block 12 during reproduction.

The first FPGA 13 uses the difference block 1 based on the I / P identification information sent from the microcomputer 40.
It is determined whether the field input in 2 is I video or P video.

When the field input to the difference block 12 is the I video, the video data is stored in the memory 31, and the video data is sent to the encoder 21 through the addition / subtraction means 32. When the field input to the difference block 12 is P video, the P video data (difference data) is sent to the addition / subtraction means 32, and the I video data (basic video data) most recently stored in the memory 31 is stored. Take the sum of. Then, the obtained video data is sent to the encoder 21.

In the example of FIG. 8, the video data of the I image "
1 "and" 7 "are stored in the memory 31 and are sent to the encoder 21. Also, the P images" 2-1 "and" 3 "are sent.
"-1", ... "6-1", "8-7", etc. are added to the I video data most recently stored in the memory 31 to restore the original video data, and then sent to the encoder 21. .

In the encoder 22, after the sent video data is returned to the analog video signal, the monitor 103
Sent to.

[5] Explanation of special reproduction [5-1] Description of operation during reverse playback

The operation when the reverse reproduction command is input to the microcomputer 40 during the normal reproduction will be described.

In the following description, the I / P group is
P that is the difference between any one I-picture and that I-picture
A group consisting of video and images.

At the time when the reverse reproduction command is input to the microcomputer 40, the data for one block (288 tracks) which is normally reproduced immediately before is input to the first memory 1.
7 or is stored in the second memory 18. Further, in the memory 31 of the difference block 12, the I / P which was reproduced immediately before the time point when the reverse rotation reproduction command was input to the microcomputer 40.
The I video of the group is stored.

Here, for convenience of explanation, the first memory 17 is used.
As shown in FIG. 9, among the data of one block stored in the sub-bank, the reverse reproduction is performed when the data of 12 fields corresponding to the index numbers 1 to 12 of the sub-bank (see FIG. 7) is normally reproduced. It is assumed that the command is input to the microcomputer 40. In FIG. 9, I indicates I video and P indicates P video. Also, I1 and P11, P12, P
13 constitutes the same I / P group, and I2 and P2
It is assumed that 1, P22 and P23 form the same I / P group, and I3 and P31, P32 and P33 form the same I / P group.

At the time of reverse reproduction, it is necessary to reproduce the data in the order of index numbers 12, 11, 10, ... 2, 1, but in each I / P group, first, the I video is reproduced. Otherwise, P video cannot be played. Therefore, during reverse playback, the second
FPGA 16, microcomputer 40 and first FPGA 1
3 performs the following control.

First, the I / P group (I3, P31, P32, P33) to be reproduced first is reproduced in reverse. That is, since the I-picture (I3) corresponding to the index number 9 is stored in the memory 31 of the difference block 12 when the reverse reproduction command is input, the memory 31
Based on the data I3 stored in
The P video is reproduced in the order of 2, P31, and then the I video I3 is reproduced. This makes index number 1
The video data of 2 to 9 is reproduced in the reverse direction.

Only the additional information is reproduced in the order of decreasing index number from index number 8,
Based on the I / P identification information included in the additional information,
I / P group (I2, P21, P2) to be reproduced next
2, the index number 5 for the I video of P23) is acquired.

The I picture (I2) corresponding to the index number 5 is reproduced. As a result, the reproduced I video (I2) is stored in the memory 31 of the difference block 12. However, the reproduced I video is controlled so as not to be output from the difference block 12.

The I / P groups (I2, P21, P22, P23) with index numbers 5 to 8 are reproduced from the reverse in the same manner as above.

Only the additional information is reproduced in order of decreasing index number from index number 4,
Based on the I / P identification information included in the additional information,
I / P group to be reproduced next (I1, P11, P1
2, index number 1 for the I video of P13) is acquired.

The I picture (I1) corresponding to the index number 1 is reproduced. As a result, the reproduced I video (I1) is stored in the memory 31 of the difference block 12. However, the reproduced I video is controlled so as not to be output from the difference block 12.

The I / P groups (I1, P11, P12, P13) with index numbers 1 to 4 are reproduced from the reverse in the same manner as.

As described above, the normal reproduction is performed at the time when the reverse reproduction command is input to the microcomputer 40.
Among the data for the block, the reverse playback command is issued by the microcomputer 4
The data up to the data that was normally reproduced when 0 is input is reproduced in the reverse direction.

In the reverse reproduction, the data is read in block units from the video tape in order from the block having the newest recording time to the old block, contrary to the normal reproduction. The data of the block immediately before the block which has been reversely reproduced as described above is stored in the memory 17 or 1.
When the reverse reproduction data is stored in a memory different from the memory in which the reverse reproduction data is stored, the data of the block is reversely reproduced by the same processing as the above processing.

[5-2] Description of operation during fast forward reproduction

In the fast-forward reproduction, the data read from the video tape is alternately stored in the memories 17 and 18 in block units, as in the normal reproduction. However, during fast-forward playback, the memory 17, 1
Of the data stored in No. 8, only the data for I video is read and reproduced.

[5-3] Description of operation during fast reverse reproduction

In the fast-reverse reproduction, the data read from the video tape is alternately stored in the memories 17 and 18 in block units, as in the reverse reproduction. However, at the time of fast-reverse playback, the memory 17, 1
Of the data stored in 8, only the data for the I video is read in the reverse direction and reproduced.

[6] Description of Search Processing by Specifying Recording Time

Next, by specifying the recording time,
A search process of reproducing a video recorded at a designated recording time (hereinafter, designated recording time) will be described.

At the time of data recording, the recording time (year, month, day, minute,
Seconds) on the control track of the videotape
It is written as S data.

FIG. 10 shows an operation procedure at the time of retrieval. First, the V written in the control track
The recording block corresponding to the designated recording time is specified based on the ASS data, and the data of the recording block is stored in the memory 1
Take in 7 (step 1).

That is, the microcomputer 40 takes in VASS data from the control track while fast-forwarding the video tape. And V which is past the specified recording time
When the ASS data is detected, the data is rewound by one block and then the reproducing operation is performed to fetch the data of the recording block immediately before the block corresponding to the VASS data after the designated recording time into the memory 17.

When the second FPGA 16 loads the data of the specified recording block into the memory 17, the sub-bank (see FIG. 7) indicating the storage head address of the frame header at the head of each field data is stored in the memory 17. create. Then, the total number of indexes is notified to the microcomputer 40 (step 2). The microcomputer 40 and the second FPGA 16 start the binary search.

That is, the microcomputer 40 first sets the second F
The PGA 16 is instructed to specify the index number in the center of the search range and requests additional information, thereby acquiring the additional information corresponding to the index number in the center of the search range (step 3). Immediately after the start of the binary search, the search range is all fields (all indexes) in the recording block specified in step 1 above.

Then, it is determined whether or not the recording time information for the field included in the acquired additional information and the designated recording time match (step 4). If they do not match, it is determined whether the target field is in front of or behind the field from which the additional information was acquired, and the search range is halved based on the result of this determination.
After narrowing down to (step 5), the process returns to step 3 and the processes after step 3 are performed.

By repeating the binary search of steps 3 to 5, a field having the same time as the designated recording time in the additional information is searched for. When a field (hereinafter referred to as a corresponding field) in which the same time as the designated recording time is included in the additional information can be searched (YES in step 4), the microcomputer 40 includes the additional information in the corresponding field. Based on the I / P identification information, it is determined whether the video of the corresponding field is an I video or a P video (step 6).

When the video of the corresponding field is the I video, the microcomputer 40 instructs the second FPGA 16 to output the data of the corresponding field (step 7). As a result, the corresponding field data is reproduced and output.

If it is determined in step 6 that the video of the corresponding field is the P video, the microcomputer 4
0 determines whether the corresponding field is in the first half or the second half of the block based on the index number corresponding to the corresponding field (step 8).

When the corresponding field is in the first half of the block, the microcomputer 40 sequentially acquires the additional information in the direction in which the index number increases, and records it later in time from the corresponding field based on the I / P identification information. The field of the I video which is the closest to the corresponding field is searched from among the generated fields (step 9). The I video is searched for in the direction of increasing index number because there is a possibility that the I video does not exist before the corresponding field in the block.

When the I-picture is found in step 9, the second FP outputs the data of the found I-picture.
Instruct the GA 16 (step 10). As a result, among the fields recorded after the corresponding field in time, the I video closest to the corresponding field is reproduced and output.

When the corresponding field is in the latter half of the block, the microcomputer 40 sequentially acquires the additional information in the direction of decreasing the index number, and based on the I / P identification information, the microcomputer 40 temporally precedes the corresponding field. Of the recorded fields, the I video field closest to the corresponding field is searched (step 11). When the I-picture is found, the second FPGA 16 is instructed to output the data of the found I-picture (step 1
2). As a result, the I video closest to the relevant field among the fields recorded temporally before the relevant field is reproduced and output.

[7] Description of backup function in case of power failure

As described above, during the recording operation,
Data is recorded on the video tape for each block.

As shown in FIG. 11, if a power failure occurs at time t1 during the recording of data in block0, the data accumulated in the memories 17 and 18 immediately before the power failure will be lost.

Immediately before the time t1, the memory 17 reads bl
If the data of ock0 is read, a part of the data of block1 is accumulated in the memory 18 immediately before the time point t1. In such a case, this digital VTR is provided with all the data and the block1 that make up the block0.
It has a backup function to continue the recording operation by the storage battery until all the data that composes the above is recorded on the video tape.

FIG. 12 shows a drive circuit for realizing the backup function at the time of power failure.

The power supply (DC output) of the microcomputer 40 and other parts in the digital VTR 102 is always
It is generated by the main power supply circuit 72 connected to the commercial power supply 71. Power is supplied to the microcomputer 40 by the battery 78 even when the power is off. The power failure detection circuit 75 monitors the output from the main power supply circuit 72 and outputs a power failure detection signal to the microcomputer 4 when a power failure occurs.
Output to 0.

The storage battery 74 is provided in the memory 17, when a power failure occurs,
It is a backup power supply for supplying a power supply for recording the data accumulated in 18 and all the data constituting the two blocks to which those data belong to the video tape. The storage battery 74 is charged by the charging circuit 73 connected to the main power supply circuit 72 when the power of the digital VTR is turned on.

The storage battery 74 is connected to the sub power supply circuit 77 via the relay 76. The relay 76 is normally in a non-operating state (OFF state), and is activated (ON state) by the microcomputer 40 when a power failure occurs.

As shown in FIG. 13, if a power failure occurs at the time t1 during the recording operation, the power failure detection signal becomes L level, so the relay control signal output from the microcomputer 40 becomes H level. Then, the relay 76 is activated. As a result, electric power is supplied from the storage battery 74 to the sub power supply circuit 77 via the relay 76, and the sub power supply circuit 77 causes the microcomputer 4 in the digital VTR 102 to operate.
0 and other parts are supplied with power source power (DC output). As a result, the recording operation is continued.

Then, the data accumulated in the memories 17 and 18 at the time of the power failure and the data to which these data belong 2
When the recording of all the data forming one block on the video tape is completed (time point t2), the microcomputer 40 sets the relay control signal to the L level and the relay 76 is turned off.

In the example of FIG. 11, when a power failure occurs at the time point t1, the microcomputer 40 sets the relay control signal to the H level and activates the relay 76. As a result, electric power is supplied from the storage battery 74 to the sub power supply circuit 77 via the relay 76, and the sub power supply circuit 77 supplies digital V
Power is supplied to the microcomputer 40 and other parts in the TR 102.

As a result, bl stored in the memory 17
The process of recording the data of ock0 on the video tape is continued, and the process of writing the data of block1 to the memory 18 is continued. When the writing of the data of block1 to the memory 18 is completed, the recording process of the data of block1 stored in the memory 18 onto the video tape is started. Then, when the recording process of the data of block 1 onto the video tape is completed, the microcomputer 40 sets the relay control signal to L level, and the relay 76 is turned off.

[0093]

According to the present invention, a special reproduction method suitable for the video recording / reproducing apparatus newly developed by the present applicant, such as reverse reproduction, fast-forward reproduction, fast-reverse reproduction, can be obtained.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a monitoring system.

FIG. 2 is a block diagram showing a schematic configuration of a digital VTR.

FIG. 3 is a time chart showing an operation at the time of recording a difference block.

FIG. 4 is a schematic diagram showing a format for data of one field recorded on a video tape.

FIG. 5 is a schematic diagram showing a timing for performing a head clogging inspection.

FIG. 6 is a timing chart for explaining a head clogging inspection performed when the video tape is stopped.

FIG. 7 is a schematic diagram showing the contents of subbanks.

FIG. 8 is a time chart showing an operation during reproduction of a difference block.

FIG. 9 is a schematic diagram showing the normally reproduced data and its index number, out of the data in the normally reproduced block immediately before the time point when the reverse reproduction command is input.

FIG. 10 is a flowchart showing a search processing procedure by designating a recording time.

FIG. 11 is a schematic diagram for explaining a backup function at the time of power failure.

FIG. 12 is a circuit diagram showing a configuration of a power supply circuit for realizing a backup function during a power failure.

13 is a time chart showing the operation of the power supply circuit of FIG. 12 when a power failure occurs.

[Explanation of symbols]

12 Difference block 13 First FPGA 14 Image compression / decompression circuit 15 Additional information addition / separation unit 16 Second FPGA 17,18 memory 19 formatter 20 Signal recording / playback unit 40 microcomputer 31 memory 32 Addition / subtraction means

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Claims (3)

(57) [Claims] 1. At the time of recording, input video data is stored in a first memory as basic video data in a predetermined number of field cycles, and the input video data is compressed and input.
In the video data, the input image data of each field until the field stored in the next first memory from a field that will be stored in the first memory includes a basic image data stored in the latest in the first memory The difference data obtained is compressed, and the obtained difference data is compressed, and each compressed data is recorded in a recording medium for each field together with identification information indicating whether the data is for the basic video data or for the difference data. a special playback in a video reproducing apparatus, at the time of normal reproduction, more field of the recording medium
Data is read in block units including the data of, and stored alternately in two second memories for each block unit,
Every time one block of data is stored in the second memory,
The data is read from the second memory in which one block of data has been stored, the read data is expanded in field units, and if the expanded field unit data is basic video data, the basic video data Is stored in the first memory and is output as reproduced video data, and when the decompressed field unit data is difference data, based on the difference data and the basic video data most recently stored in the first memory. To restore the original video data, output the obtained video data as playback video data, and if a reverse playback command is input during normal playback, the data is returned for normal playback until immediately before. From the last read data in the second memory that had been read, in the direction of the oldest recording time, and now in the first memory by the normal reproduction operation. Up to the data corresponding to the stored basic video data is sequentially read in the reverse direction to perform reverse reproduction. When reverse reproduction is performed for older data thereafter, 1 is set.
For each data group corresponding to one basic video data and one or more difference data obtained by subtracting the difference from the basic video data, first the data for the basic video data is decompressed and stored in the first memory, A special reproduction method in a video recording / reproducing apparatus, wherein reverse reproduction is performed by sequentially reading out each data in a data group in a reverse direction. 2. At the time of recording, input video data is stored in a first memory as basic video data in a predetermined number of field cycles, and the input video data is compressed and input.
In the video data, the input image data of each field until the field stored in the next first memory from a field that will be stored in the first memory includes a basic image data stored in the latest in the first memory The difference data obtained is compressed, and the obtained difference data is compressed, and each compressed data is recorded in a recording medium for each field together with identification information indicating whether the data is for the basic video data or for the difference data. A special playback method in a video recording / playback device, in which multiple fields are recorded from the recording medium during fast-forward playback.
Data is read in block units including minute data and stored alternately in two second memories for each block unit, and one block of data is stored every time one block of data is stored in the second memory. The compressed data corresponding to the basic video data is read out from the second memory in which the storage of the data has been completed in order from the oldest recorded time to the newest and expanded, and the expanded video data is output as reproduced video data. Special playback method in a video recording / playback device. 3. At the time of recording, input video data is stored in a first memory as basic video data in a predetermined number of field cycles, and the input video data is compressed and input.
In the video data, the input image data of each field until the field stored in the next first memory from a field that will be stored in the first memory includes a basic image data stored in the latest in the first memory The difference data obtained is compressed, and the obtained difference data is compressed, and each compressed data is recorded in a recording medium for each field together with identification information indicating whether the data is for the basic video data or for the difference data. a special playback in a video reproducing apparatus, rewind during reproduction, a plurality fields from the recording medium
Minute blocks of data, and reads the data so that the recording time goes to the old block, and alternately stores the data in two second memories for each block, and one block of data is stored in the second memory. Each time, the compressed data corresponding to the basic video data is read out from the second memory, which has stored one block of data, in the order from the newest recording time to the oldest, and is expanded. A special reproduction method in a video recording / reproducing apparatus, characterized in that the special reproduction method outputs the reproduced video data.