JPH08186791A - Video recorder - Google Patents

Abstract

PURPOSE: To provide a video recorder which can surely record the important moments in the case of executing a long time recording. CONSTITUTION: The image data compressed by a JPEG system are transfered to a bus line 9 under the control of a CPU 8 and then successively recorded at and after the starting address of an endless recording medium 11 via an I/F 10. When the image data are recorded up to the final address of the medium 11, the data recorded on the medium 11 are read out and then compressed again by the thinning carried out in every frame or field. These compressed data are recorded on an external recording medium 17 via the I/F 10. At the same time, the data to be inputted next are overwritten at and after the starting address of the medium 11. Then the medium 11 can be divided into an endless recording area and a thinned data area with no use of the medium 17.

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 for recording a long-time video signal taken by a surveillance camera.

[0002]

2. Description of the Related Art Generally, video signals recorded by surveillance cameras are recorded in traffic, production lines, crime prevention, etc.
Recording for 24 hours is required for reproduction.
As a video recording / reproducing apparatus of this type, a VTR (video tape recorder) capable of recording for a maximum of 6 hours is generally used, and recording for 24 hours is possible by intermittently recording by repeating stop / start. There is known a Time Lapse VTR capable of performing.

[0003]

[Problems to be Solved by the Invention] However, the VTR
Uses a tape, there is a problem that the tape needs to be processed endlessly when performing endless recording, and when two VTRs are used alternately, the tape is used. However, there is a problem in that replacement work is required.

Further, when the VTR is used, there is a problem that recording cannot be performed when necessary due to abrasion of the tape and adhesion of dust to the head. For example, a car accident when monitoring traffic, It becomes impossible to record the moment when a defective product occurs when monitoring the production line, or the moment when money is stolen from the cash register in the case of crime prevention.

In view of the above conventional problems, it is an object of the present invention to provide a video recording apparatus capable of reliably recording an important moment when recording for a long time.

[0006]

In order to achieve the above object, the present invention sequentially records video data from the head address of the recording area of the first recording medium, and when the video data is recorded up to the last address, the first data is recorded. The video data of the recording medium is compressed by frame-by-frame or field-by-frame compression and transferred to the second recording medium, and the video data is recorded again from the start address of the recording area of the first recording medium. ing. That is, according to the present invention, the compression means for compressing the video signal photographed by the camera on a frame-by-frame or field-by-field basis, and the video data compressed by the compression means in order from the start address of the recording area of the first recording medium. When the image data is recorded and recorded up to the final address, the video data of the first recording medium is compressed by frame-by-frame or field-by-frame compression and transferred to the second recording medium, and is also compressed by the compression means. There is provided a video recording apparatus having recording control means for controlling to record again the video data from the head address of the recording area of the first recording medium.

According to the present invention, the video data is sequentially recorded from the first address of the first recording area of the recording medium, and when the data is recorded up to the last address of the first recording area, the video data of the first recording area is recorded. The frame data is compressed by frame-by-frame or field-by-field compression and transferred to the second recording area of the recording medium, and the video data is recorded again from the head address of the first recording area of the recording medium. That is, according to the present invention, the compression means for compressing the video signal photographed by the camera on a frame-by-frame or field-by-field basis, and the video data compressed by the compression means in order from the top address of the first recording area of the recording medium When the data is recorded and recorded up to the final address of the first recording area, the video data of the first recording area is compressed by frame-by-frame or field-by-frame compression and transferred to the second recording area of the recording medium. In addition, there is provided a video recording device having recording control means for controlling to record the video data compressed by the compression means again from the head address of the first recording area.

[0008]

According to the present invention, video data is sequentially recorded from the first address of the recording area of the first recording medium, and when the final address is recorded, the video data of the first recording medium is recorded in frame units or field units. Since it is compressed by dropping and transferred to the second recording medium, and the video data is recorded again from the start address of the recording area of the first recording medium, an important moment is surely ensured when recording for a long time. Can be recorded.

Further, according to the present invention, the video data is sequentially recorded from the head address of the first recording area of the recording medium, and when the data is recorded up to the last address of the first recording area, the video data of the first recording area is recorded. Is compressed by frame-by-frame or field-by-field compression and transferred to the second recording area of the recording medium, and video data is recorded again from the start address of the first recording area of the recording medium. When recording, important moments can be surely recorded.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. 1 is a block diagram showing an embodiment of a video recording / reproducing apparatus according to the present invention, FIG. 2 is a block diagram showing in detail the video switcher / signal processing apparatus and A / D converter group of FIG. 1, and FIG. 1 is a block diagram showing in detail the JPEG encoder / decoder unit of FIG. 1, FIG. 4 is an explanatory diagram showing processing of the JPEG encoder / decoder unit of FIG. 3, and FIG.
4 is a flowchart for explaining a recording operation of the video recording / reproducing apparatus of FIG.

In FIG. 1, the input system of the video switcher / signal processing device 1 is composed of four systems (video 1 to 4), and each system has a composite video signal from a camera, a Y (luminance) signal and a C ( Color) signals (Y / C signals) can be input. FIG. 2 is a block diagram showing details of the video switcher / signal processing device 1 and the A / D converter group 2. That is, the video switcher / signal processing device 1
Is a circuit portion 1a, 1b of a portion surrounded by a dotted line in FIG.
1c and 1d, the A / D converter group 2 has three A / D converters 2a, 2b and 2c. In the video switcher 1a, one of each system is selected, and when both the composite video signal and the Y / C signal are input, the switch of the S terminal (not shown) gives priority to the selection of the Y / C input. It

When the composite video signal is selected by the video switcher 1a, the Y / C separation circuit 1b separates the Y signal and the C signal, and the C signal is separated by the NTSC color decoder 1d. −
Y) and (B-Y). The Y signal, the color difference signals (RY), and (BY) are respectively supplied to the A / D converter group 2
The A / D converters 2a to 2c convert into digital data by the sampling clock synchronized with the input signal.

Returning to FIG. 1, the frame memory 3 has one frame of Y data, (RY) data, and (BY) data that are A / D converted by the A / D converters 2a to 2c during compression. To store raster block converter 4
Output to. In addition, the A / D converters 2a to 2c when not compressed
An E-E system switch 18 is provided to directly output the data to the D / A converter 6a. At the time of decompression, one frame of Y data from the raster / block converter 4 (R-
The Y) data and the (BY) data are stored in the frame memory 3 and output to the D / A converter 6a via the switch 18.

Here, in the present embodiment, compression is performed by using a block of 8 × 8 pixels of an image as one unit.
Since the video signal of the SC signal is a one-dimensional signal on the time axis, vertical data cannot be extracted as it is. Therefore, the raster / block converter 4 reads the video data of 8 lines stored in the frame memory 3 during compression, temporarily stores it in the line buffer, converts the data into 8 × 8 pixel block data, and
Output to the EG encoder / decoder unit 5. Further, at the time of decompression, the block data of 8 × 8 pixels decompressed by the JPEG encoder / decoder unit 5 is set to 1 on the time axis.
In order to convert into a dimensional signal, video data for 8 lines is temporarily stored in the line buffer and output.

Next, the JPEG encoder / decoder unit 5
The configuration will be described with reference to FIG. JPEG method is CC
An image compression algorithm for color still image transmission and storage that has been internationally standardized by the joint use of ITT and ISO.
The basic system algorithm of the JPEG method is the following 3
It can be divided into two stages. (1) Removal of redundancy in image data by two-dimensional DCT (discrete cosine transform) (2) Quantization of DCT coefficient adapted to human visual characteristics (3) Entropy coding (Huffman of quantized DCT coefficient (Encoding) When decompressing, the steps (3) → (2) → (1) are performed in reverse.

In JPEG, the image data is a 1 × 8 × 8 pixel.
The DCT / IDCT unit 5a handles two-dimensional DCT processing on one block of raster-block converted image data at the time of compression (IDC).
"I" in T means INVERSE = opposite). In this case, first, DCT processing is performed on 8 pixels in the horizontal direction, and then DCT processing is performed in the vertical direction, whereby a matrix of 8 × 8 DCT coefficients is generated.

At this stage, the image signal is transformed into DCT coefficients, ie spatial frequency components, in this case the horizontal
The spatial frequency component of the block in both the vertical direction has a characteristic that it becomes larger as the frequency becomes lower, and it rapidly decreases as the frequency becomes higher. Therefore, the higher the number of “0” of the DCT coefficient value, the higher the compression rate obtained. To be At the time of decompression, the DCT / IDCT unit 5a restores the DCT coefficient to the image data of one block (inverse DCT).

In the quantizer / inverse quantizer unit 5b, the DCT coefficients sent from the DCT / IDCT unit 5a during compression are weighted in accordance with human visual characteristics, and the DCT coefficients are It has a role of increasing the number of “0” s. Specifically, the 8 × 8 DCT coefficient is multiplied by the 8 × 8 weighting coefficient of the quantization table 5c, and the result is passed to the encoder 5d.

At this stage, the amount of compressed data can be changed by changing the constant of the quantization table 5c.
Factor), the resulting compressed data size will be a different amount. In the quantizer / inverse quantizer unit 5b, the compressed data is restored to the DCT coefficient (inverse quantization) at the time of expansion.

In the Huffman encoder / decoder section 5d,
At the time of compression, as shown in FIG. 4, the quantized DCT coefficients are zigzag scanned in ascending order of horizontal and vertical frequency components. The reason for this is that high coefficient values are concentrated in the lower frequency component both horizontally and vertically, and "0" data increases in the higher frequency component, so that the "0" data is rearranged so as to be continuous. is there.

The data string thus rearranged is divided into a DC coefficient and an AC coefficient as shown in FIG.
For the DC coefficient, the difference from the DC coefficient of the immediately preceding block is coded (DPCM coding), and for the AC coefficient, the Huffman code is used for coding. The Huffman code is a method of assigning a code having a high code probability to a code having a short code length in accordance with the appearance probability of data, and therefore the Huffman table 5e is required. In the Huffman encoder / decoder unit 5d, the encoded data is restored (decoded) into the quantized data of the DCT coefficient at the time of decompression.

Also, reproduced digital data (Y, R
-Y, BY) is transferred to the video external synchronization output and video output unit 6 via the frame memory 3. In this block 6, the D / A converter 6a converts it into an analog signal, and the signal processing unit 6b and the horizontal / vertical synchronization signal generator 7 convert it into an NTSC signal. , Y / C signals are mixed to output a composite video signal. Also, an external synchronizing signal C. SYNC1 ~
4 is output from the video output / distributor 6c. It should be noted that the video external synchronization output and video output unit 6 and the three input systems may be optionally configured as shown by the broken lines in FIG.

The image data thus compressed by the JPEG system is transferred to the bus line 9 under the control of the CPU 8 and then recorded on the endless recording medium 11 via the I / F 10. As the recording medium 11, a magnetic disk device or a magneto-optical disk device capable of recording / reproducing with a non-contact head is used. The bus line 9 also has a ROM in which the programs of the CPU 8 are stored in advance.
12, a RAM 13 having a work area for the CPU 8,
Time code unit 14 for generating time information and external control I /
The F15 is connected, and the operation panel 16 and an external recording medium 17 can be connected to the external control I / F 15.

Next, the operation of the above embodiment will be described. Here, when the transfer speed of the recording medium 11 is about 2 Mbytes / sec, the image data is generally 640 × 480 pixels × 2YC (luminance signal and color signal) = 614.4 Kbytes and 614.4 Kbytes in the case of NTSC signals. Since it is × 30 frames / sec = 18.42 Mbytes / sec, it cannot be recorded on the recording medium 11 as it is.

Therefore, in this embodiment, first, for example, the NTSC signal is compressed to about 1/20 by the JPEG method (= 0.92 Mbytes / second). Further, it may be compressed to 0.46 Mbytes / second by dropping one field. Then, by transferring the data to the recording medium 11 in the margin time generated by this compression, recording is performed from the head address of the recording medium 11 as shown in FIG. 5 (step S1). Further, the image data recorded on the recording medium 11 is given a number for each frame or each field under the control of the CPU 8.

Then, the compressed data is sequentially recorded on the recording medium 1.
When the data is recorded in No. 1 and up to the final address of the recording medium 11 (step S2), the data recorded in the recording medium 11 is read and further compressed by performing frame reduction (thinning out) in frame units or field units, I /
The data is recorded on the external recording medium 17 via F10 (step S3), and the next input data is recorded on the recording medium 1.
Overwrite from the first address of 1 (or record after erasing)
Yes (step S1). That is, the external recording medium 17
Since the NTSC signal has a rate of 30 frames / second, 90 frames are compressed and recorded when one frame is extracted every 3 seconds.

Therefore, according to the above embodiment, the video data is recorded endlessly on the recording medium 11, and the video data is thinned out and recorded on the external recording medium 17, so that long-time recording is performed. You can reliably record and play important moments. Instead of recording the endless data in the recording medium 11 and the thinned data in the external recording medium 17, the recording medium 11 is recorded in the endless recording area (first storage area) and the thinned data area (second storage area). ).

[0028]

As described above, according to the present invention, video data is sequentially recorded from the head address of the recording area of the first recording medium, and the video of the first recording medium is recorded when the last address is recorded. Since the data is compressed by frame-by-frame or field-by-field compression and transferred to the second recording medium, and the video data is recorded again from the start address of the recording area of the first recording medium, long-time recording is possible. You can be sure to record important moments when you do.

Further, according to the present invention, the video data is sequentially recorded from the head address of the first recording area of the recording medium, and when the video data is recorded up to the last address of the first recording area, the video data of the first recording area is recorded. Is compressed by frame-by-frame or field-by-field compression and transferred to the second recording area of the recording medium, and video data is recorded again from the start address of the first recording area of the recording medium. When recording, important moments can be surely recorded.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of a video recording / reproducing apparatus according to the present invention.

FIG. 2 is a block diagram showing in detail the video switcher / signal processing device and the A / D converter group of FIG.

FIG. 3 is a block diagram showing the JPEG encoder / decoder unit of FIG. 1 in detail.

FIG. 4 is an explanatory diagram showing a process of a JPEG encoder / decoder unit of FIG.

5 is a flowchart for explaining a recording operation of the video recording / reproducing apparatus of FIG.

[Explanation of symbols]

1 Video Switcher / Signal Processor 2 A / D Converter Group 3 Frame Memory 4 Raster Block Converter 5 JPEG Encoder / Decoder Section (Composing Means Together with Raster Block Converter) 6 Video External Synchronous Output and Video Output Section 7 synchronization signal generator 8 CPU (recording control means) 9 bus line 10 I / F (interface) 11 recording medium (first recording medium) 12 ROM 13 RAM 14 time code section 15 external control I / F 16 operation panel 17 Recording medium (second recording medium)

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Takeo Murayama 3-12 Moriya-cho, Kanagawa-ku, Yokohama, Kanagawa Japan Victor Company of Japan, Ltd. (72) Tomoaki Suzuki 3--12 Moriya-cho, Kanagawa-ku, Yokohama Address inside Victor Company of Japan, Ltd.

Claims (2)

[Claims] 1. A compression unit for compressing a video signal captured by a camera in frame units or field units, and video data compressed by the compression unit is sequentially recorded from a start address of a recording area of a first recording medium. When the data up to the final address is recorded, the video data of the first recording medium is compressed by frame-by-frame or field-by-frame compression and transferred to the second recording medium, and at the same time, the video compressed by the compression means. A video recording apparatus having a recording control means for controlling to re-record the data from the head address of the recording area of the first recording medium. 2. A compression unit for compressing a video signal captured by a camera in frame units or field units, and video data compressed by the compression unit is sequentially recorded from a head address of a first recording area of a recording medium. , First
If the last address of the recording area of the
The video data in the recording area is compressed by frame-by-frame or field-by-field compression and transferred to the second recording area of the recording medium, and the video data compressed by the compression means is recorded in the first recording area. A video recording apparatus having recording control means for controlling recording again from a head address.