JP2002262273A - Digital supervisory system and supervisory camera - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a digital supervisory system that prevents data in excess of a transmission capability of a network from being transmitted and realizes video recording for a long time without deteriorating the image quality. SOLUTION: The digital supervisory system is configured with a detection means that detects an intruder or the like, a variable compression means that can revise a frame rate at compression of a digital video signal and a GOP(Group of Picture) configuration of the MPEG or the like, and a control means that controls the variable compression means and a resolution conversion means depending on a signal from the detection means.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a digital monitoring system using a digital recording device such as a hard disk recorder. In particular, the present invention relates to a digital surveillance system configured by connecting a plurality of surveillance cameras to a network and a surveillance camera suitable for the present system.

[0002]

2. Description of the Related Art In recent years, compression of JPEG, MPEG, etc., large-capacity hard disks and high-speed interfaces,
With the speeding up of LAN, digital video /
A digital monitoring system for transferring voice data to a digital recording device using a hard disk or the like via a digital LAN has become feasible. For example, JP-A-7
JP-A-212748, JP-A-2000-83241 and JP-A-2000-13744 disclose a digital monitoring system.

[0003]

In the above-mentioned digital recording apparatus, media such as a hard disk used for recording digital video / audio data have been increasing in capacity year by year, but use of a compression technique such as MPEG. Even
There is still a problem that the recording time is short.

For example, if the image size of one frame is horizontal 7
When a moving image of 30 frames per second is compressed by MPEG with 20 pixels and 480 pixels vertically, it depends on the compression rate. (0.5MB / s). When a hard disk of about 40 GB is used as a recording medium, the recording time is 40 GB ÷ 0.5 MB = 800.
00 (Second) = 22 (hour). This is the case of only the moving image 1ch. In a surveillance system, it is necessary to record images from a plurality of cameras, and the recording time is further reduced.

On the other hand, if an attempt is made to increase the compression ratio in order to extend the recording time, the image quality is degraded, and the original purpose of the monitoring system for identifying an intruder cannot be achieved. Furthermore, when a plurality of surveillance cameras are connected to a network and used, if the data output from the plurality of surveillance cameras exceeds the data transmission capability of the network, there is a problem that data from the cameras cannot be transmitted at all.

[0006] Japanese Patent Application Laid-Open No. Hei 7-21748 discloses that
A monitoring camera system that streamlines monitoring work by sending the output signal of the monitoring camera according to the detection output of the abnormality detection unit to the signal recording and playback unit among the output signals from multiple monitoring cameras Have been. However, according to this method, an output signal from a camera in which no abnormality is detected by the abnormality detection unit is not recorded, and if a malfunction of the abnormality detection unit occurs, the image cannot be checked later.

Japanese Unexamined Patent Application Publication No. 2000-013744 discloses a time lapse method in which frame thinning control information is output to a variable length encoding circuit so that, for example, a variable length code for an I picture is output to a recording / reproducing apparatus in normal times. A recorder is described. However, it does not disclose a method of recording images from a plurality of surveillance cameras and a transmission method when a plurality of surveillance cameras are connected to a network and used.

Japanese Patent Application Laid-Open No. 2000-83241 describes a network camera monitoring system that controls the amount of image data transferred by monitoring network traffic and controlling the aperture. However, in the method of controlling the aperture, the image quality deteriorates, and the screen displayed on the monitor or the like becomes difficult to see. Furthermore, when the alarm information is transferred, if the network traffic is congested, it is described that the minimum necessary image data is sent while checking the degree of communication congestion. Is not described.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a digital surveillance system capable of preventing data exceeding the transmission capacity of a network from being transmitted and realizing long-time recording without deteriorating image quality.

[0010]

In order to solve the above-mentioned problems, a surveillance system according to the present invention has a plurality of surveillance cameras connected via a network, and the surveillance cameras are capable of changing a data compression ratio of a video signal. And a control means for controlling the variable compression means so as not to exceed the transfer capacity of the network. Further, the monitoring system according to the present invention includes a detecting means for detecting an intruder, a variable compressing means capable of changing a frame rate or a picture configuration when compressing a video signal, and the variable compression And control means for controlling the means.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a monitoring system according to an embodiment of the present invention. In FIG. 1, 1 is an optical lens, 2 is an image sensor, 3 is a camera digital signal processing circuit, 4 is a resolution conversion circuit, 5 is a variable compression circuit, 6
Is a control circuit, 7 is a LAN interface, 8 is a detector, 9 is a camera, 10 is a digital network, 11
Is a recorder.

First, an image is converted into an electric signal in the image pickup device 2 through the optical lens 1. The camera digital signal processing circuit 3 processes a signal output from the image sensor to generate a digital video signal such as a luminance signal / color signal. The digital signal output from the camera digital signal processing circuit 3 is supplied to a resolution conversion circuit 4. The detector 8 detects whether an abnormal situation such as the presence of an intruder or an intruder has occurred, and supplies the detection result to the control unit 6. The detector 8 can be constituted by, for example, an infrared sensor.

The resolution conversion circuit 4 converts the resolution of the digital signal in accordance with the control signal supplied from the control circuit 6, and converts the resolution-converted digital video signal into a variable-compressed signal in which the data compression method of the image signal is variable. Supply to circuit 5.
The variable data compression circuit 5 compresses the digital signal supplied by the compression method specified by the control signal of the control means. That is, the variable data compression circuit 5 controls the frame rate during compression and the GOP (Group of Pictur) of MPEG.
e) Change the configuration. The digital video signal after data compression is supplied to the LAN interface 7. And L
The AN interface 7 is connected via a network 10
The digital video signal after data compression is supplied to the recorder 11.

When the detector 8 detects an intruder, the control circuit 6 sets the resolution conversion circuit 4 to a normal resolution, and sets the variable data compression circuit 5 to a normal frame rate and data compression method. If the detector 8 does not detect an intruder, the resolution conversion circuit 4 is set so as to reduce the resolution (the number of pixels) of the digital video signal. Then, the variable data compression circuit 5 lowers the frame rate to be encoded and sets so as to perform data compression by a data compression method corresponding to the frame rate. If the encoding method is MPEG, it is set so as to have an optimal GOP structure according to the frame rate. Thereby, the amount of bits output from the variable compression unit can be reduced.

Further, by reducing the pixel size in addition to reducing the frame rate, the bit amount can be further reduced. For example, the pixel size is set to 1/2 both horizontally and vertically, and the data compression ratio is set to 1/9 of the normal value.
When (1/2) × (1/2) × (1/9) = 1
/ 36.

In the monitoring system, when there is no intruder or the like or when there is no image change, the importance of the image information is low, and it is not necessary to record a detailed image. On the other hand, when there is an intruder and there is an image change, the importance of the image information is high, and it is necessary to record detailed image information. The present invention can realize long-time recording without losing important video information by utilizing characteristics required for a surveillance system.

In the embodiment described above, the resolution conversion circuit 4 and the variable data compression circuit 5 are provided.
Only the variable data compression circuit 5 may be used. In this case, since the image is compressed only in the time axis direction, the image quality does not deteriorate as in the case where the resolution is changed, and the observer can easily confirm the image on a screen such as a monitor. Also, by reducing the number of frames to be encoded by the variable data compression circuit 5 when there is no intruder, the power consumption of the camera itself can be reduced.

The data transfer capacity of the network 10 has an upper limit. If the camera 9 that detects the intruder raises the frame rate, the data transfer capacity of the camera 10 may exceed the data transfer capacity of the network 10. In particular, when a plurality of cameras 9 simultaneously detect an intruder and increase the frame rate, it is necessary to adjust the amount of data generated by each camera so as not to exceed the data transfer capability of the network 10. In the present embodiment, the camera 9 that has detected the intruder notifies the recorder 11 of this. The recorder 11 instructs the cameras 9 connected to the network 10 on encoding conditions (frame rate, GOP configuration, bit rate) and the like via the network 10 so as not to exceed the data transfer capability of the network 10. . For example, it instructs the camera 9 that has not detected an intruder to further reduce the frame rate or stop data transfer. When the detection of an abnormal situation such as an intruder ends,
An instruction is issued to restore the encoding conditions or to resume data transmission.

Similarly, the maximum data recording rate of the recorder 11 also has an upper limit, and this upper limit may be lower than the data transfer rate of the network. In this case, similarly,
The recorder 11 indicates the encoding conditions (frame rate, GOP configuration, bit rate) of each camera via the network 10 so as not to exceed the maximum data recording rate of the recorder 11.

As described above, even if the number of cameras is increased, by changing the encoding method itself of each camera, it is possible to operate properly without exceeding the transmission capacity of the network. Can be.
In this embodiment, a system having two cameras has been described. However, the same effect can be obtained even when three or more cameras are provided.

When another device such as a PC (personal computer) is connected to the network 10 in addition to the monitoring camera 9, the encoding condition of the camera 9 is changed according to the amount of data transmitted from the PC or the like. You may do it. In this case, the data transmission amount may be directly notified to the camera 9 from a PC or the like, and the encoding condition of each camera 9 may be controlled. By performing such control, it is possible to avoid a situation in which data from the camera cannot be transmitted at all because the transmission capacity of the network is exceeded.

FIG. 5 shows an example of a change in the frame rate and the encoding method of the variable data compression circuit 5 when MPEG is used as the data compression method. FIG.
(A) shows a compression method when there is an intruder, and 1 GOP is composed of 15 pictures of I (intra-frame compression) picture, B (bidirectional prediction) picture, and P (omnidirectional prediction) picture. . The frame rate in this case is
30fps. (B) and (C) show the compression method when there is no intruder. (b) is composed of an I (intra-frame compression) picture and a B (bidirectional prediction) picture, and the frame rate is 1/3 of (a) of 10 fps.
(C) is one I (intra-frame compression) picture (c)
Only, and the frame rate is 2 fps. (I
(Picture), (P picture), and (B picture) are assigned the code amounts of 6: 3: 1, (a), (b),
The code amount of (c) is 14: 9: 3.

FIG. 5 shows examples (b) and (c) as configurations excluding B and P pictures from the configuration (a).
However, the present invention is not limited to the configuration of the GOP based on the configuration of FIG. For example, the interval of each frame of the IP picture is larger than that in the case of FIG.
A GOP may be composed of one I picture and three P pictures at frame (0.5 second) intervals. I
Assuming that the interval of each frame of the P picture is a 15-frame interval, one I picture and three P pictures
In the case of constructing P, an additional 15
The code amount can be reduced to / 24. As described above, in the present invention, the code amount can be freely changed by changing the GOP configuration.

FIG. 6 shows an example of the relationship between the detection signal of the detection means and the encoding mode. In this example, (a) and (c) of FIG. 5 are used as the compression method. “IBP” and “Ionly” in FIG. 6 indicate the compression schemes of FIGS. 5A and 5C, respectively. FIG. 6A shows the transition of the encoding mode.
(B) shows the output signal of the detection circuit. In the output signal of the detection circuit, the “High” period indicates an alarm period when an intruder is present.

FIG. 7 shows the relationship between the encoding mode and the detection signal when the resolution of the video signal is changed by the detection means in addition to the change in the compression ratio. As in FIG. 6, FIG. 7A shows the transition of the encoding mode, and FIG. 7B shows the output signal of the detection circuit. The output of the camera signal processing is the resolution of REC 601 (horizontal: 720 pixels × vertical: 480 in the NTSC system).
Pixel), and if there is an intruder, the resolution conversion circuit does not perform the reduction processing,
Encoding is performed in a 30 fps mode using B and P pictures. If there is an intruder, the resolution conversion circuit performs a reduction process to SIF (horizontal: 352 pixels × vertical: 240 pixels), and compresses the data to 2 fps by I picture.
s encoded.

In the embodiment shown in FIG. 1, the infringer is detected by the detector 8 constituted by, for example, an infrared sensor or the like. However, as shown in FIG. An infringer may be detected from a video signal. As the detection method, 1) detection of a difference in average level of a video signal, 2) detection by a sum of absolute values of difference values with other temporally adjacent frames, 3) detection by a difference in signal level distribution, and the like. Performed by According to the detection circuit 8, there is an advantage that the detection circuit 8 can be constituted by purely digital signal processing, and the IC of the detection circuit can be incorporated.

Further, as shown in FIG. 3, an infringer may be detected based on information obtained at the time of data compression. When MPEG is used as data compression, motion vectors for motion compensation, Intra / Inter judgment for each MB, etc.
Data useful for detecting intruders can be obtained. From these data, the detection circuit 8 detects an intruder. The method of determining an intruder is 1) it is determined that there is an intruder if the number of vectors in a certain direction exceeds a predetermined number in a certain area due to the distribution of motion vectors. 2) Intr
When the number of macroblocks of a becomes equal to or greater than a preset value, it is determined that there is an intruder. 3) A determination is made based on a combination of the determination results of the above 1) and 2). In the case where such information cannot be taken out from the variable data compression circuit, the MPEG compressed data contains the above-described results such as the motion vector and the Intra / Inter determination for each MB for decoding. A configuration may be adopted in which information obtained by decoding the output compressed data to some extent is obtained.

Further, as shown in FIG. 4, a configuration may be adopted in which an intruder is detected by a detection device 14 which is not built in the camera 9 placed on the network. Detector 14
Comprises a detection circuit 8, a LAN interface 12, and a control circuit 13. The control circuit 13 outputs a detection signal of the detection circuit 8 to the network 10 via the LAN interface 12. The recorder 11 receives the detection signal output to the network and sends a control signal to the camera 9 in accordance with the information, thereby changing the settings of the resolution conversion circuit 4 and the variable data compression circuit of the camera 9. . In FIGS. 3 and 4, only one camera 9 is omitted, but the system is not limited to a system having one camera.

The detection circuit and detector for detecting the presence or absence of an abnormal situation may be provided in the recorder 11 or a device such as a PC connected to a network. Further, the detection device may be connected to the camera. Further, in the above embodiment, the case where the encoding condition is controlled by the recorder 11 has been described. However, a configuration in which the encoder 11 is controlled by a control device provided outside the recorder 11, such as the detection device 14 or a PC, may be used. good.

[0030]

According to the present invention, it is possible to provide a digital surveillance system capable of preventing data exceeding the transmission capacity of the network from being transmitted and realizing long-time recording without deteriorating image quality.

[Brief description of the drawings]

FIG. 1 is a diagram showing a monitoring system according to an embodiment of the present invention.

FIG. 2 shows an example of an abnormal situation detection method in the monitoring system according to the embodiment of the present invention.

FIG. 3 shows an example of an abnormal situation detection method in the monitoring system according to the embodiment of the present invention.

FIG. 4 shows an example of an abnormal situation detection method in the monitoring system according to the embodiment of the present invention.

FIG. 5 is a diagram showing a modified example of a frame rate and an encoding method.

FIG. 6 is a diagram illustrating an example of a relationship between a detection signal of a detection unit and an encoding mode.

FIG. 7 is a diagram illustrating a relationship between an encoding mode and a detection signal when the resolution of a video signal is changed.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Lens 2 Image sensor 3 Camera signal processing 4 Resolution conversion circuit 5 Variable data compression circuit 6, 13 Control circuit 7, 12 LAN interface 8 Detector 9 Camera 10 Digital network 11 Recorder 14 Detector

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (Reference) H04N 5/765 H04N 5/91 L 5/915 K 5/92 5/92 H 7/32 7/137 Z (72) Inventor Naoki Yamamoto 292 Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa Prefecture Inside Digital Media Development Headquarters, Hitachi, Ltd. (72) Inventor Hironori Komi 292 Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa Prefecture Digital Media Development Division, Hitachi, Ltd. (72) Inventor Norihiko Nakano 292 Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa Hitachi, Ltd (72) Inventor Tomoyuki Nonaka 292 Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa Prefecture Digital Media Development Headquarters, Hitachi, Ltd. (72) Inventor Tatsushi Nishimura 292 Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa Address Stock Company Date Inside the Digital Media Development Division of the Works (72) Inventor Ryo Oba 292 Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa Prefecture Inside the Digital Media Development Division of Hitachi, Ltd. (72) Tomoyuki Kurashige 292 Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa Address F-term in Hitachi Image Information Systems Co., Ltd. F-term (reference) TA07 TB03 TB07 TC12 TC25 TD01 UA02 5C084 AA02 AA07 AA14 BB31 CC17 DD11 FF08 FF27 GG43 GG52 GG78 GG80 HH10 HH12 HH13 5C087 AA02 AA03 AA22 AA24 BB11 BB32 BB74 DD05 GG14 GG19 FF19 GG19 FF19 GG19 FF19 GG19 FF19 GG19 FF01 GG19 FF19 GG19 FF19 GG19 FF19 GG19 FF19 GG19 FF18

Claims (9)

[Claims] 1. A plurality of imaging means having compression means for compressing a video signal and outputting video data; a transmission means connected to the plurality of imaging means for transmitting the video data; and a transmission capability of the transmission means. Control means for controlling a data compression ratio of the compression means so as to change a frame rate or a picture configuration of the video data so as not to exceed the following. 2. The apparatus according to claim 1, wherein said plurality of image pickup means include detection means for detecting an intruder. The control means controls to reduce a data compression ratio of a compression means of the image pickup means in which an infringer is detected by said detection means. The digital surveillance system according to claim 1, wherein: 3. An MPEG compression means for MPEG-compressing a video signal into video data, a variable data compression means capable of changing a picture configuration of the video data, and an output means for outputting the video data. A recording unit that records the video data on a recording medium, a transmission unit that transmits an output from the camera to the recording unit, and controls the variable data compression unit according to a transmission amount of the transmission unit. A digital surveillance system, comprising: 4. A variable data compression means capable of changing a picture configuration at the time of data compression of a video signal, and, when an intruder or an intruder is detected, increasing the data compression frame rate of said variable data compression means, Control means for controlling data compression by a picture configuration corresponding to the rate. 5. A digital surveillance system using digital data compression, comprising: a data compression section for compressing a video signal; a detection means for detecting an intruder or an intruder; a frame rate and a picture rate when the video signal is compressed; A variable data compression unit that can change the configuration, and a control unit that changes an encoding format of the variable data compression unit in accordance with a signal from the detection unit, wherein an intruder or an intruder is not detected by the detection unit. Reducing the data compression frame rate of the variable data compression means, controlling the data compression with a picture configuration optimized for the frame rate, and recording the compressed video data output by the variable data compression means. Digital surveillance system characterized in that it is supplied to Temu. 6. The detecting means receives a digital video signal and outputs a detection signal when a difference between frames of a video luminance level or a difference between frames of luminance level distribution information exceeds a certain value. The digital monitoring system according to claim 5, wherein the digital monitoring system is configured to output. 7. The detecting means has input means for inputting motion vector information generated at the time of data compression by the variable data compressing means or encoding determination information within a frame or between frames. The digital surveillance system according to claim 5, wherein an intruder or an intruder is detected from the information. 8. The detecting means includes extracting means for extracting motion vector information or intra-frame or inter-frame encoding determination information from the digital video signal after the data compression, and detects an intruder from the extracted information. The digital surveillance system according to claim 5, wherein the system is configured to detect an intruder. 9. The variable data compression means has a resolution conversion means for changing an image resolution, and when no intruder or intruder is detected by the detection means, the control means controls the resolution conversion to reduce the image resolution. 9. A digital surveillance system according to claim 5, wherein said means for controlling means is controlled.