JP3416560B2 - Video recording apparatus, video reproducing apparatus, and video recording / reproducing apparatus - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a video recording device,
The present invention relates to a video reproducing device and a video recording / reproducing device.

[0002]

2. Description of the Related Art A time-division multiplexed video signal from a multiplexer which sequentially switches and outputs video images picked up by a plurality of surveillance cameras every one field period is compressed by an image compression device and compressed data is recorded on a video tape. A video recording / reproducing apparatus having a recording apparatus for recording and a reproducing apparatus for reading compressed data recorded on a video tape, expanding the read compressed data by an image expanding apparatus, and outputting the expanded data to a multiplexer has already been developed.

[0003]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a video recording device, a video reproducing device and a video recording / reproducing device capable of reducing the amount of recorded data.

[0004]

A video recording apparatus according to the present invention is a time-division multiplexed video signal obtained by time-division-multiplexing video signals from a plurality of video cameras. In a video recording apparatus for recording a time-division multiplexed video signal on a recording medium to which information about the camera number of a video camera corresponding to each included field signal is added, a plurality of video recording devices provided corresponding to the camera numbers are provided . basic image storage unit, when each field group of the same camera number that includes consist field each other which is added to the division multiplexed video signal, a predetermined number of fields periods, the camera number that is added to the field group Store the video data as basic video data in the corresponding basic video storage and
In it the image means for sending the compression means, time division multiplexing each field group of field each other to that contained in the video signal same camera number is added, the Fi
Stored in the basic image storage means of the image data of the field group
It is then stored in the basic image storage unit from the field to be
That for the video data of each field between the up field, takes the difference between the basic image data stored in the latest in the basic image storage means, means for sending the difference data obtained in the image compression unit, and the image compressing means characterized in that the compressed data for each field unit, which is compressed, along with the identification information and the camera number that compressed data indicating that for those or difference data for the basic image data, and a means for recording on a recording medium by And

The video reproducing apparatus according to the present invention is defined in claim 1.
A video reproducing apparatus for reproducing data recorded on a recording medium by the described video recording apparatus, comprising means for reading compressed data, identification information and camera number from the recording medium, and compressed data read from the recording medium for each field unit. Image decompression means for decompressing the data into the data before being compressed by the image compression means, and identification information indicating whether the field unit data decompressed by the image decompression means is basic video data or difference data. If the field-unit data expanded by the image expansion means is basic video data, the basic video data is stored in the basic video storage means corresponding to the camera number corresponding to the basic video data. depending on it means for outputting, and the image expansion means as reproduced video data together and stores the If the data of the decompressed field unit is difference data, the original on the basis of the basic image data stored in the latest in the basic image storage means corresponding to the camera number corresponding to the difference data and the difference data It is characterized by including means for restoring the video data and outputting the obtained video data as reproduced video data.

The video recording / reproducing apparatus according to the present invention is a time-division multiplexed video signal obtained by time-division-multiplexing video signals from a plurality of video cameras, each of which is included in the time-division multiplexed video signal. Video recording provided with a recording device for recording a time-division multiplexed video signal on a recording medium, to which information about a camera number of a video camera corresponding to a field signal is recorded, and a reproducing device for reproducing data recorded on the recording medium. in the reproducing apparatus, a recording apparatus, a plurality of basic image SL <br/>憶means provided corresponding to the camera number, time division multiplexed video signal same camera number that is included in is added field for each field group composed of each other, a predetermined number of fields periods, the basic image storage means corresponding to the camera number that is added to the field group, video de In it the image means for sending the compression means, time division multiplexing each field group of field each other to that contained in the video signal same camera number is added to the video data stores the data as the basic image data, the Of the video data of the field group,
Then from basic field stored in the basic image storage unit
For the video data of each field up to the field stored in the video storage means, the difference from the latest basic video data stored in the basic video storage means is calculated, and the obtained difference data is sent to the image compression means. means, and the compressed data for each field unit, which is compressed by the image compressing means, along with the identification information and the camera number that compressed data indicating that for those or difference data for the basic image data, means for recording on a recording medium The reproducing apparatus is provided with a unit that reads compressed data, identification information, and a camera number from the recording medium, expands the compressed data read from the recording medium on a field-by-field basis, and compresses the compressed data by the image compressing unit. Image decompression means for returning to data, data in field units decompressed by the image decompression means A unit for discriminating whether the image data is the main image data or the difference data based on the identification information, and when the data in the field unit expanded by the image expansion unit is the basic image data, the basic image data is Basic corresponding to the camera number corresponding to the video data
When the data stored in the video storage means and output as reproduction video data as it is, and the data in field units expanded by the image expansion means are difference data, the difference data and the camera number corresponding to the difference data are added. It is characterized in that it is provided with means for restoring the original video data on the basis of the latest basic video data stored in the corresponding basic video storage means and outputting the obtained video data as reproduced video data.

[0007]

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

[1] Description of Overall Configuration of Monitoring System FIG. 1 shows the overall configuration of the monitoring system.

The surveillance system includes four video cameras (hereinafter referred to as surveillance cameras) 101 to 104 and video signals A to A obtained by these surveillance cameras 101 to 104.
A video multiplexer 105 which receives D as an input and generates a time division multiplexed video signal, a digital VTR 106 for compressing the time division multiplexed video signal generated by the video multiplexer 105 and recording it on a video tape, and a digital VTR 106 for reproduction. And a monitor 107 for displaying an image selected by the video multiplexer 105 among the time division multiplexed image signals.

The video multiplexer 105 outputs the video signal A of the surveillance camera 101 in one field period, outputs the video signal B of the surveillance camera 102 in the next field period, and the surveillance camera 103 in the next field period. The video signal C is output, and the video signal D of the surveillance camera 104 is output in the next field period. The video signal to be output for each field period is sequentially switched and output for each surveillance camera 101 to 104. To do.
The video signal obtained by time-division-multiplexing the video signals from the plurality of surveillance cameras 101 to 104 is referred to as a time-division multiplexed video signal.

In each field of the time-division multiplexed video signal output from the video multiplexer 105, camera numbers A, B, C and D indicating which of the surveillance cameras 101 to 104 are the input video signals A to D, respectively. And the like are multiplexed in the vertical blanking period. Hereinafter, the information multiplexed in the vertical blanking period will be referred to as a VBI signal.

The time division multiplexed video signal output from the video multiplexer 105 is sent to the digital VTR 106. The digital VTR 106 compresses the time-division multiplexed video signal sent thereto and records it on a video tape.

At the time of reproduction, the video multiplexer 105 reads the VBI signal for each field from the reproduction output (time-division multiplexed video signal) from the digital VTR 106, and based on the camera number represented by the read VBI signal, the field. It is determined whether or not the image is a video signal to be presented. When it is determined that the video signal is to be presented, the image of the field is stored in the image memory in the video multiplexer 105. Then, when the video for a predetermined field is accumulated in the image memory, the video is read from the image memory and the monitor 107 is read.
To display.

[2] Description of the recording operation of the video signal processing circuit of the digital VTR 106

FIG. 2 shows the configuration of the video signal processing circuit of the digital VTR 106.

During recording, the video multiplexer 105
The analog video signal sent from the decoder 11
Is converted into digital video data by. The video data obtained by the decoder 11 is VBI information separation /
The VBI data is separated by the encoding unit 12 and then sent to the difference block 13.

The VBI information separating / encoding unit 12 separates the VBI data from the video data sent from the decoder 11 and sends it to the first FPGA (Field Programmable Gate Array) 14, and the VBI data is simpler. To the first FPGA 14.

FIG. 3 shows a concrete example of encoding VBI data.

The VBI signal included in the time division multiplexed video signal output from the multiplexer 105 is shown in FIG.
As shown in (a) and (b), they are multiplexed in the vertical blanking period of the 10th to 20th horizontal lines. The VBI signal contained in each of these horizontal lines is converted into 8 bits × 768 pieces of VBI data by the decoder 11.

The VBI information separating / encoding unit 12 firstly
By slicing this VBI data at a predetermined level, 1 bit × 7 as shown in FIG.
Convert to 68 data. Then, as shown in FIG. 3 (d), continuous 8 data are added to generate 3-bit data, and only the most significant bit thereof is taken to average them. In other words, if the added value of the data for eight is 0 to 3 in decimal, these eight data are set to 1
If the bit data is "0" and the decimal number is 4 to 8, these eight data are converted into 1-bit data "1". As a result, 8 bits × 768 pieces of VBI data are converted into 1 bit × 96 pieces of VBI encoded data.

Decoding of such VBI encoded data is performed as follows. If the VBI encoded data is "1", it is converted into eight data strings of "1". VBI
If the encoded data is "0", it is converted into eight data strings of "0". Thus, first, the VBI encoded data is converted into 1 bit × 768 pieces of data. Next, out of 1 bit × 768 data, 8 bits representing “0” are assigned to “0” data, and “1” is assigned.
8 bits representing "255" are allocated to the data of. As a result, VBI consisting of 8 bits × 768
Data is obtained.

The difference block 13 includes a memory 31 and addition / subtraction means 32. The memory 31 corresponds to a plurality of surveillance cameras 101 to 104, that is, 4
Four storage areas EA, EB, EC, ED are provided corresponding to one camera number A, B, C, D. The memory 31 is controlled by the first FPGA 14.

FIG. 4 shows the operation of the difference block 13 during recording.

The first FPGA 14 separates VBI information.
The camera number is decoded based on the VBI data sent from the encoding unit 12, and the camera number corresponding to the field input to the difference block 13 is determined.

Then, the first FPGA 14 is provided for each field group including fields to which the same camera number is added, which are included in the time division multiplexed video data output from the VBI information demultiplexing / encoding unit 12. In a predetermined field number cycle (for example, 6 vertical period cycles), video data is stored as basic video data in the areas EA, EB, EC, ED corresponding to the camera numbers added to the field group in the memory 31. At the same time, the video data is sent through the addition / subtraction means 32 to the image compression / expansion circuit 15.

In each field group consisting of fields to which the same camera number is added, which are included in the time-division multiplexed video data output from the VBI information separation / encoding unit 12, that field group in the memory 31 Area EA, EB corresponding to the camera number added to
The video data of each field between the field where the video data is stored in EC and ED and the field where the video data is stored next in the area EA, EB, EC and ED is sent to the addition and subtraction means 32. The areas EA, EB,
The difference from the basic video data stored latest in the EC and ED is obtained, and the obtained difference data is used as the image compression / expansion circuit 15.
Sent to.

In the example of FIG. 4, each surveillance camera 101-10.
4 image data A1, B1, C1, D1 is stored in the memory 31
Area EA, EB, EC corresponding to that camera number in
The video data is stored in the EDs and is sent to the image compression / decompression circuit 15.

The image data A1, B1, C1, D1 of the surveillance cameras 101 to 104 stored in the memory 31 are also stored.
From the video data stored in the memory 31 to the field next stored in the memory 31, the difference between the video data stored in the memory 31 and the video data having the same camera number is calculated. It is sent to the image compression / decompression circuit 15.

The video data (basic video data) that has passed through the addition / subtraction means 32 and is sent to the image compression / expansion circuit 15 is called I video data, and after the difference from the basic video data is taken by the addition / subtraction means 32. Image compression / decompression circuit 15
The video data (difference data) sent to P is referred to as P video data.

The image compression / expansion circuit 15 compresses the video data sent from the difference block 13 for each field unit by, for example, the JPEG system. The compressed video data (encoded data) obtained by the image compression / expansion circuit 15 is sent to the additional information / VBI information adding / separating unit 16.

On the other hand, the microcomputer 40 uses the additional information / VBI
The I / P identification information indicating whether the compressed video data sent to the information adding / separating unit 16 is the I video data or the P video data, the camera number corresponding to the compressed video data, and the VBI information encoded data are the first. From the FPGA 14, and sends it to the additional information / VBI information adding / separating unit 16 together with the recording time information (current year, month, day, minute, second).

In the additional information / VBI information adding / separating unit 16, the compressed video data obtained by the image compression / expansion circuit 15 is added to the I / P identification information corresponding to the compressed video data sent from the microcomputer 40 and the camera. Additional information such as a number and recording time information and VBI encoded data are added. The data to which the predetermined data is added by the additional information / VBI information adding / separating unit 16 is the second FPGA 17
Sent to.

The second FPGA 17 receives additional information / VBI.
The data sent from the information adding / separating unit 16 is alternately written into the two memories 18 and 19 for each predetermined block unit including a plurality of fields of data, and one block of data is written into the memory. The data is read from the memory in which the writing of the data for one block is completed and sent to the formatter 20. In this example, one block includes 288 tracks of data including information about audio.

That is, the second FPGA 17 writes the data sent from the additional information / VBI information adding / separating unit 16 into one memory, for example, the first memory 18. When the writing of the data for one block to the first memory 18 is completed, the memory for writing the data is switched to the other second memory 19 and at the same time,
Data reading is started from the first memory 18.

The data read from the first memory 18 is sent to the formatter 20. Then, when the reading of one block of data from the first memory 18 is completed, the reading is stopped.

After that, when the writing of the data for one block to the second memory 19 is completed, the memory for writing the data is switched to the first memory 18, and at the same time, the second memory is written.
Reading of data from the memory 19 is started. Second
The data read from the memory 19 is the formatter 2
Sent to 0. Then, when the reading of the data for one block from the second memory 19 is completed, the reading is stopped. After that, similar processing is repeated.

The formatter 20 converts the sent data into data having a data structure which can be recorded on a video tape. The data obtained by the formatter 20 is recorded on the video tape via the recording amplifier and the video head in the signal recording / reproducing unit 21. That is, as shown in FIG. 5, one block (28
Video data is recorded in units of tracks. The video tape is stopped each time the recording of data in units of one block is completed. The videotape runs idle for about 38 tracks from the start and then stops.

The second FPGA 17 and the formatter 20 are controlled by the microcomputer 40.

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

At the time of reproduction, the video head in the signal recording / reproducing section 21 reads data from the video tape in block units. The read video data is reproduced by the reproduction amplifier and formatter 2 in the signal recording / reproducing unit 21.
It is sent to the second FPGA 17 via 0.

The second FPGA 17 alternately writes the sent data to the two memories 18 and 19 for each block, and every time one block of data is written into the memory, one block worth of data is written. The data is read from the memory where the writing of the data is completed and the additional information / VBI is read.
It is sent to the information addition / separation unit 16.

In the additional information / VBI information adding / separating unit 16, the additional information such as the camera number, the I / P identification information, the time information and the V information are sent from the received data for one field.
BI encoded data and the like are separated. The separated data is sent to the first FPGA 14 via the microcomputer 40.

The data after the predetermined data is separated by the additional information / VBI information adding / separating unit 16 is sent to the image compression / expansion circuit 15 and expanded in units of one field. The video data obtained by the image compression / expansion circuit 15 is sent to the difference block 13.

FIG. 6 shows the operation of the difference block 13 during reproduction.

The first FPGA 14 discriminates the camera number corresponding to the field input to the difference block 13 based on the camera number sent from the microcomputer 40, and the difference block 13 based on the I / P identification information. It is determined whether the input field is I video or P video.

When the field input to the difference block 13 is the I image, the area EA in the memory 31 corresponding to the camera number corresponding to the field,
The video data is stored in EB, EC, and ED, and the video data is sent to the VBI information decoding / VBI information adding section 21 through the addition / subtraction means 32.

When the field input to the difference block 13 is a P image, the P image data (difference data) is sent to the addition / subtraction means 32, and it corresponds to the camera number corresponding to the field in the memory 31. Area EA, E
The sum of the I video data (basic video data) most recently stored in B, EC, and ED is calculated. Then, the obtained video data is sent to the VBI information decoding / VBI information adding section 21.

In the example of FIG. 6, the video data "A" of the I image is displayed.
1 ”,“ B1 ”,“ C1 ”, and“ D1 ”are stored in the areas EA, EB, EC, and ED corresponding to the camera number corresponding to the field in the memory 31, respectively, and VBI information decoding / VBI is performed. It is sent to the information adding unit 21.

Further, the video data of P video "A2-A"
1 "," B2-B1 "," C2-C1 "," D2-D "
1 "and the like are I video data" A1 "," B1 "," C most recently stored in the areas EA, EB, EC, ED corresponding to the camera number corresponding to the field in the memory 31.
After adding 1 ”and“ D1 ”to restore the original video,
It is sent to the VBI information decoding / VBI information adding section 21.

VBI information decoding / VBI information adding section 21
Also, VBI encoded data separated by the additional information / VBI information adding / separating unit 16 is sent from the first FPGA 14. The VBI information decoding / VBI information adding unit 21 receives the VBI information sent from the first FPGA 14.
The encoded data is decoded by the method described above. Then, the decoded VBI data corresponding to the video data is added to the video data sent from the difference block 13 to the VBI information decoding / VBI information adding section 21.

VBI information decoding / VBI information adding section 21
The video data to which the VBI data has been added is returned to an analog video signal by the encoder 22 and then sent to the video multiplexer 105.

[4] Description of error processing during reproduction of the video signal processing circuit

At the time of reproduction, there is a possibility that an error has occurred in the data read from the video tape by the video head. A method of detecting such an error and a process when the error is detected will be described.

FIG. 7 shows the format of data for one field recorded on the video tape.

The data block for one field is the first
Header section 51, second header section 52, third header section 53,
Audio additional data section 54, audio data section 55
And a video data section 56. The first header portion 51 is 32 words, the second header portion 52 is 64 words, the third header portion 53 is 64 words, the audio additional data portion 54 is 32 words, and the audio data portion 55 is 32 × m.
(M is an integer of 1 or more) words, the video data section 56 has 32
Xn (n is an integer of 1 or more) words such as 5
The number of words 1 to 56 is determined to be 32 words × k (k is an integer) as shown in FIG. The audio additional data section 54 includes an audio data section 55.
It includes data indicating m that defines the number of words in.

The first header section 51 includes I / P identification information,
The recording time information (year, month, day, hour, minute, second) and additional information such as camera number are included. As the I / P identification information, for example, "EXFFh" is used and is inserted as a frame header at the head of the first header section 51.
Here, “EXFF” is 16 for “h” of “EXFFh”
It represents a decimal number, and if "X" in "EXFF" is 0, it represents I video, and if "X" is 1, it represents P video.

The second header section 52 includes a quantization table (Q table). The third header portion 53 contains VBI encoded data. The first header for error detection (for example, "E4FFh") is inserted at the beginning of the third header section 53.

At the beginning of the audio additional data section 54,
Second header for error detection (for example, "E7FFh")
Has been inserted. At the beginning of the video data section 56, a third error detecting header (for example, "D8FFh") is inserted. At the end of the video data portion 56, an end code (EOI; for example, "D9FFh") indicating the end of the video data portion is inserted.

At the time of reproduction, the second FPGA 17 receives the frame header "EXFFh" from the data sent from the formatter 20, and the first error detection header "E4FF".
h ”, second error detection header“ E7FFh ”, third error detection header“ D8FFh ”and end code“
While confirming "D9FFh", the data sent from the formatter 20 is written in the memory 18 or 19.

The second FPGA 17 has a formatter 20.
When the frame header "EXFFh" is detected from the data sent from the second FPGA 17 to the second FPGA 17, counting of the number of words is started. And the first header for error detection "
When the count number corresponding to the position where "E4FFh" is inserted is reached, it is confirmed whether or not the first header for error detection exists, and if the first header for error detection cannot be confirmed, an error has occurred. To judge.

If the first error detecting header "E4FFh" can be confirmed when the count number corresponding to the position where the first error detecting header "E4FFh" is inserted is reached, the second error detecting header "E7FFh" can be confirmed. When the count number corresponding to the position where "is inserted" is reached, it is confirmed whether or not the second header for error detection exists, and if the second header for error detection cannot be confirmed, an error has occurred. to decide.

When the second header for error detection can be confirmed when the count number corresponding to the position where the second header for error detection "E7FFh" is inserted, if the second header for error detection can be confirmed, the third header for error detection " When the count number corresponding to the position where "D8FFh" is inserted is reached, it is confirmed whether or not the third header for error detection exists, and if the third header for error detection cannot be confirmed, an error has occurred. To judge.

The error detection third header "D8FF"
The count number corresponding to the position where h ″ is inserted is obtained by acquiring data indicating m that defines the number of words of the audio data portion 55 included in the audio additional data portion 54.

When the second FPGA 17 determines that an error has occurred, the second FPGA 17 returns the pointer to the address where the end code (EOI) of the field immediately preceding the pertinent field has been written, and determines that the error has occurred. The writing of data to the memory is stopped until the frame header of the field next to is sent.
When the frame header of the field next to the field determined to have an error is sent, the pointer is advanced by 1 and writing of the data of the field is started.

[0065]

According to the present invention, it is possible to obtain a video recording device, a video reproducing device and a video recording / reproducing device capable of reducing the amount of recorded data.

[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 VBI by a VBI separation / VBI information encoding unit.
FIG. 6 is a schematic diagram for explaining a data encoding method.

FIG. 4 is a time chart showing an operation at the time of recording a difference block.

FIG. 5 is a schematic diagram showing that data is recorded in blocks on a video tape.

FIG. 6 is a time chart showing an operation during reproduction of a difference block.

FIG. 7 is a schematic diagram showing a format for data of one field recorded on a video tape.

[Explanation of symbols]

12 VBI separation / VBI information coding unit 13 Difference block 14 First FPGA 15 Image compression / decompression circuit 16 Additional information / VBI information addition / separation unit 17 Second FPGA 18, 19 memory 20 Formatter 21 Signal recording / playback unit 40 microcomputer 31 memory 32 Addition / subtraction means

─────────────────────────────────────────────────── ─── Continuation of front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) H04N 5/76-5/956 H04N ^7/ 24-7/68

Claims (3)

(57) [Claims] 1. A time-division multiplexed video signal obtained by time-division-multiplexing video signals from a plurality of video cameras, the video camera corresponding to each field signal included in the time-division multiplexed video signal. In a video recording apparatus for recording a time-division multiplexed video signal to which information about the camera number of is recorded on a recording medium, a plurality of basic images provided corresponding to the camera numbers are provided.
Image memory means, when each field group of the same camera number that includes consist field each other which is added to the division multiplexed video signal, a predetermined number of fields periods, corresponding to the camera number that is added to the field group In the basic video storage means,
In it the image means for sending the compression means, time division multiplexing each field group of field each other to that contained in the video signal same camera number is added to the video data stores the image data as the basic image data, Of the video data of that field group, the basic
From the field stored in the video storage means, next to the basic video
For the video data of each field up to the field stored in the storage means, a means for taking a difference from the basic video data most recently stored in the basic video storage means, and sending the obtained difference data to the image compression means , and compressed data for each field unit, which is compressed by the image compressing means, along with the identification information and the camera number that compressed data indicating that for those or difference data for the basic image data, means for recording on a recording medium, the A video recording device characterized by being provided. 2. A video reproducing apparatus for reproducing data recorded on a recording medium by the video recording apparatus according to claim 1, wherein the compressed data, the identification information and the camera number are read from the recording medium, and the recording medium is read. Image decompression means for decompressing the compressed data for each field unit and returning to the data before being compressed by the image compression means, is the field unit data decompressed by the image decompression means the basic video data? A means for discriminating whether the data is difference data based on the identification information, and when the data in field units expanded by the image expansion means is basic video data, the basic video data is converted into a camera corresponding to the basic video data. means for output as the reproduced image data with is stored in the basic image storage means corresponding to the number, If and data field units decompressed by the image decompression unit is difference data, and the difference data and the basic image data stored in the latest in the basic image storage means corresponding to the camera number corresponding to the difference data A video reproducing apparatus, comprising means for restoring the original video data based on the above, and outputting the obtained video data as reproduced video data. 3. A time-division multiplexed video signal obtained by time-division-multiplexing video signals from a plurality of video cameras, the video camera corresponding to each field signal included in the time-division multiplexed video signal. In a video recording / reproducing apparatus including a recording device for recording a time-division multiplexed video signal to which the information regarding the camera number is recorded on a recording medium, and a reproducing device for reproducing data recorded on the recording medium, the recording device is , Provided for each camera number
A plurality of basic image storage unit, when each field group Including same camera number on consists fields each other that are attached to the division multiplexed video signal, a camera at a predetermined number of fields periods, are added to the field group A means for storing the video data as basic video data in the basic video storage means corresponding to the number and sending the video data as it is to the image compression means, included in the time division multiplexed video signal. in each field group of field each other that same camera number have Ru is added, the field group
In the video data, the video data for each field until field <br/> de which is then stored in the basic image storage unit from Fi <br/> Rudo stored in the basic image storage unit, group
A means for taking a difference from the basic video data most recently stored in the video storage means, sending the obtained difference data to the image compression means, and a pressure for each field unit compressed by the image compression means. The playback device is provided with a means for recording the compressed data on a recording medium together with identification information indicating whether the compressed data is for basic video data or differential data and a camera number. A unit for reading information and a camera number, an image decompressing unit for decompressing compressed data read from a recording medium for each field unit, and decompressed by the image decompressing unit for returning to data before being compressed by the image compressing unit. A means for discriminating whether the data in field units is basic video data or differential data based on the identification information, an image If the data of the field unit, which is stretched by the tension means is the basic image data, the basic image data, it causes stored basic image <br/> storage means corresponding to the camera number corresponding to the basic image data its as reproduced video data
If the field unit data decompressed by the image decompression means is the difference data, the difference data and the basic image storage means corresponding to the camera number corresponding to the difference data are stored in the latest. Restore the original video data based on the basic video data
An image recording / reproducing apparatus comprising means for outputting the obtained image data as reproduced image data.