Patent Publication Number: US-2022239826-A1

Title: Network surveillance camera system and method for operating same

Description:
This application claims the benefit of U.S. Patent Application No. 62/857,106, filed on Jun. 4, 2019, in the United States Patent and Trademark Office and the benefit of Korean Patent Application No. 10-2019-0143648, filed on Nov. 11, 2019, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference in its entirety. 
    
    
     BACKGROUND 
     1. Field 
     An embodiment of the present invention relates to a surveillance camera system, and more particularly, to a video surveillance system using a network camera and an operating method thereof. 
     2. Description of the Related Art 
     A recent surveillance camera system can transmit various video analysis information acquired in a surveillance region by using a network camera that performs intelligent video analysis together with image and audio signals. 
     In such a network-based surveillance camera system, media streaming using RTP/RTSP is widely used, and in a video receiving device such as a network camera, DVR (Digital Video Recorder), NVR (Network Video Recorder), and video surveillance standardization organizations such as ONVIF as well, a standard protocol is adapted for media streaming using RTP/RTSP. 
     RTSP (Real Time Streaming Protocol) is a standard communication protocol (RFC2326) developed by IETF and is used to remotely control the media server. In order to transmit media streaming data including video and audio, the RTP (Real-time Transport Protocol) is mainly used together as a transport layer. 
     SUMMARY 
     In an embodiment of the present invention, provided are a network surveillance camera system for, in transmitting a video and audio signal detected in a surveillance region of a network camera to a video receiving device, transmitting video analysis information of the surveillance region corresponding to the detected video and audio signal together with a still image for a specific analysis region among the video analysis information in real time, and a method of operating the same. 
     In addition, provided are a network surveillance camera system capable of transmitting the video analysis information implemented as text-based metadata by extending the existing RTP/RTSP streaming protocol and a still image for the specific analysis region in real time, and a method of operating the same. 
     In order to achieve the above object, a network surveillance camera system according to an embodiment of the present invention comprises a camera for photographing a surveillance region to acquire video and audio signals for the surveillance region; and a video receiving device connected to the camera through network for receiving data from the camera in real time, wherein the camera comprises a metadata generation unit for generating video analysis information corresponding to the surveillance region as text-based metadata; and a still image generation unit for generating a still image by cropping a video portion corresponding to an identifiable object detected within the surveillance region from among the video analysis information. 
     Wherein real time transmission of the data may be implemented by an RTP/RTSP streaming protocol. 
     Wherein an RTP header of the data transmitted in real time may include an RTP fixed header and an RTP extension header, and the RTP extension header may include an extension header ID and an object ID for the detected object. 
     Wherein the object ID may be an identifier of a video analysis object described in the metadata. 
     Wherein the RTP extension header may further include an extension field including coordinate information, at which the detected object is located in a corresponding original video region, and/or attribute information indicating an attribute of the detected object. 
     Wherein the metadata may include detection information, identification information, and location information of an object photographed in the surveillance region. Wherein the still image may be selected as a still image capable of recognizing a specific object among video data photographed in the surveillance region, and the still image may be implemented as a JPEG image file. 
     Wherein the video receiving device may generate a thumbnail image by using the still image. 
     The method of operating a network surveillance camera system according to an embodiment of the present invention comprises acquiring a video/audio signal for a surveillance region by photographing the surveillance region; generating video analysis information corresponding to the surveillance region as text-based metadata; generating a still image by cropping a video portion corresponding to an identifiable object detected within the surveillance region among the video analysis information; transmitting the video/audio signal, metadata, and still image in real time by an RTP/RTSP streaming protocol; and monitoring the surveillance region by receiving the video/audio signal, metadata, and still image. 
     Wherein generation of the metadata and the still image may be performed by adding a tag requesting generation of the metadata and the still image when a RTSP DESCRIBE instruction is transmitted. 
     Wherein an RTP header of the data transmitted in real time may include an RTP fixed header and an RTP extension header, and the RTP extension header may include an extension header ID and an object ID for the detected object. 
     Wherein the object ID may be an identifier of a video analysis object described in the metadata. 
     Wherein the RTP extension header may further include an extension field including coordinate information, at which the detected object is located in a corresponding original video region, and/or an attribute information indicating an attribute of the detected object. 
     Wherein the metadata may include detection information, identification information, and location information of an object photographed in the surveillance region. 
     Wherein the still image may be selected as a still image capable of recognizing a specific object among video data photographed in the surveillance region, and the still image may be implemented as a JPEG image file. 
     The step of generating a thumbnail image by using the still image may be further included. 
     According to this embodiment of the present invention, by providing a still image of an identifiable specific region among the video analysis information for the surveillance region, the video data of the surveillance region can be more quickly and accurately searched by using the image information without a client such as a video receiving device performing a separate video decoding procedure. 
     In addition, when a client requests a video through the RTP/RTSP streaming protocol, in addition to the video/audio signal for the surveillance region, the video analysis information implemented as text-based metadata by extending the existing RTP/RTSP streaming protocol and still images for the specific analysis region can be transmitted in real time. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       These and/or other aspects will become apparent and more readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings in which: 
         FIG. 1  is a block diagram schematically showing the configuration of a network surveillance camera system according to an embodiment of the present invention; 
         FIG. 2  is a block diagram showing the configuration of the camera shown in FIG.  1 ; 
         FIG. 3  is a block diagram showing an embodiment of the internal configuration of the processor shown in  FIG. 2 ; 
         FIG. 4  is a block diagram showing the configuration of the video receiving device shown in  FIG. 1 ; 
         FIG. 5  is a block diagram showing an embodiment of the internal configuration of the processor shown in  FIG. 4 ; 
         FIG. 6  is a view showing an embodiment of performing real-time video streaming between a client and a server using the RTP standard; 
         FIG. 7  is a diagram showing an example of media information responding between a client and a server through RTPS DESCRIBE in a network surveillance camera system according to an embodiment of the present invention; 
         FIG. 8  is a view showing an example of an RTP header used in video streaming according to an embodiment of the present invention; and 
         FIG. 9  is a diagram illustrating a method of operating a network surveillance camera system according to an embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     The above contents described in the background of the present invention are only for helping the understanding of the background of the technical idea of the present invention, and therefore it cannot be understood as content corresponding to the prior art known to those skilled in the art of the present invention. 
     In the following description, for purposes of explanation, numerous specific details are set forth to aid understanding of various embodiments. It will be evident, however, that various embodiments may be practiced without these specific details or in one or more equivalent manners. In other instances, well-known structures and devices are shown in block diagram in order to avoid unnecessarily obscuring the various embodiments. 
     Since each block of the accompanying block diagram may be executed by computer program instructions (execution engine), and these computer program instructions may be loaded on the processor of a general-purpose computer, special-purpose computer, or other programmable data processing equipment, the instructions executed by the processor of a computer or other programmable data processing equipment will generate means for performing the functions described in each block of the block diagram. 
     These computer program instructions may also be stored in a computer-usable or computer-readable memory which may direct a computer or other programmable data processing equipment to implement a function in a particular manner, and thus it is also possible that the instructions stored in the computer-usable or computer-readable memory are produced as an article of manufacture containing instruction means for performing the functions described in each block of the block diagram. 
     And, since the computer program instructions may be mounted on a computer or other programmable data processing equipment, a series of operational steps may be performed on the computer or other programmable data processing equipment to generate a computer-executed process so that the instructions for executing a computer or other programmable data processing equipment may provide function for performing the functions described in each block of the block diagram. 
     Additionally, each block may represent a part of a module, segment, or code including one or more executable instructions for executing specified logical functions, and in some alternative embodiments, it is also possible for functions described in the blocks or steps to occur out of sequence. 
     That is, the two illustrated blocks may be substantially simultaneously performed, and the blocks may also be performed in the reverse order of the corresponding functions, if necessary. 
     The terminology used herein is for the purpose of describing particular embodiments and not for the purpose of limitation. Throughout the specification, when a part “includes” a certain component, it means that other components may be further included, rather than excluding other components, unless otherwise stated. Unless otherwise defined, terms used herein have the same meaning as commonly understood by those skilled in the art, to which this invention belongs. 
     Hereinafter, embodiments of the present invention will be described in more detail with reference to the accompanying drawings. 
       FIG. 1  is a block diagram schematically showing the configuration of a network surveillance camera system according to an embodiment of the present invention. 
     Referring to  FIG. 1 , a network surveillance camera system according to an embodiment of the present invention comprises a camera  100 , network  200 , and a video receiving device  300 , and has the configuration in that data of the camera  100  is transmitted to the video receiving device  300  through the network  200 , and an administrator can monitor the data transmitted from the camera  100  using the video receiving device  300 . That is, in the embodiment of the present invention, the camera  100  may serve as a server transmitting data, and the video receiving device  300  may serve as a client receiving the transmitted data. 
     The camera  100  photographs the surveillance region to acquire video and audio signals for the surveillance region, which may photograph the surveillance region in real time for the purpose of surveillance or security. 
     The camera  100  can be implemented as a PTZ camera capable of panning and tilting and adjusting the zoom magnification of the lens, and the camera  100  may be implemented as a network camera that performs an intelligent video analysis function. Accordingly, the camera  100  according to the embodiment of the present invention may generate the video analysis information corresponding to the surveillance region in the form of text-based metadata. For example, the metadata may be written in an XML format. 
     The metadata may include object detection information (movement, sound, intrusion into a designated area, etc.) and object identification information (person, car, face, hat, clothes, etc.) photographed in the surveillance region, and detected location information (coordinates, size, etc.), and such metadata is transmitted to the video receiving device  300  through the network  200  in real time together with the video and audio signals detected in the surveillance region, and is used for real-time control and video search. Therefore, it can be used to increase control convenience and search efficiency. 
     The camera  200  according to an embodiment of the present invention generates the text-based metadata and captures a still image for a specific analysis region among the video analysis information, and transmits it together in real time. For example, the still image may be implemented as a JPEG image file. 
     The camera  100  may transmit information to the video receiving device  300  using various wired and wireless communication methods such as Ethernet, Wi-Fi, and Bluetooth, and may receive an instruction from the video receiving device  300 . 
     The network  200  may encompass, for example, a wired network such as LANs (Local Area Networks), WANs (Wide Area Networks), MANs (Metropolitan Area Networks), ISDNs (Integrated Service Digital Networks), or a wireless network such as wireless LANs, CDMA, Bluetooth, satellite communication, but the scope of the present invention is not limited thereto. 
     The video receiving device  300  may receive and store data transmitted from the camera  200 , and perform an operation of analyzing and monitoring it. Accordingly, the video receiving device  300  may be implemented as a DVR (Digital Video Recorder), a NVR (Network Video Recorder), a VMS (Video Management System), or the like, or as an application installed in a mobile terminal. 
       FIG. 2  is a block diagram showing the configuration of the camera shown in  FIG. 1 , and  FIG. 3  is a block diagram showing an embodiment of the internal configuration of the processor shown in  FIG. 2 . 
     Referring first to  FIG. 2 , the camera  100  includes an image sensor  110 , an encoder  120 , a memory  130 , an event sensor  140 , a processor  140 , and a communication interface  150 . 
     The image sensor  110  performs a function of acquiring a video by photographing a surveillance region, and may be implemented with, for example, a CCD (Charge-Coupled Device) sensor, a CMOS (Complementary Metal-Oxide-Semiconductor) sensor, etc. 
     The encoder  120  performs an operation of encoding the video acquired through the image sensor  110  into a digital signal, and it may follow, for example, H.264, H.265, MPEG (Moving Picture Experts Group), M-JPEG (Motion Joint Photographic Experts Group) standards or the like. 
     The memory  130  may store video data, audio data, still images, metadata, and the like. As mentioned above, the metadata may be text-based data including object detection information (movement, sound, intrusion into a designated area, etc.) and object identification information (person, car, face, hat, clothes, etc.) photographed in the surveillance region, and a detected location information (coordinates, size, etc.). 
     In addition, the still image is generated together with the text-based metadata and stored in the memory  130 , and it may be generated by capturing image information for a specific analysis region among the video analysis information. For example, the still image may be implemented as a JPEG image file. 
     For example, the still image may be generated by cropping a specific region of the video data determined to be an identifiable object among the video data of the surveillance region detected for a specific region and a specific period, and it may be transmitted in real time together with the text-based metadata. In this case, the metadata may be written in XML format. 
     The communication interface  150  transmits the video data, audio data, still image, and/or metadata to the video receiving device  300 . The communication interface  150  according to an embodiment may transmit video data, audio data, still images, and/or metadata to the video receiving device  300  in real time. The communication interface  150  may perform at least one communication function among wired and wireless LAN (Local Area Network), Wi-Fi, ZigBee, Bluetooth, and Near Field Communication. 
     The processor  140  controls the overall operation of the camera  100 , which may be configured to process instructions of a computer program by performing basic arithmetic, logic, and input/output operations. Instructions may be provided to processor  140  by memory  130  or communication interface  150 . For example, the processor  140  may be configured to execute a received instruction according to a program code stored in a recording device such as the memory  130 . That is, the processor  140  may include a program module that is implemented by software such as C, C++, Java, Visual Basic, Visual C, and the like and performs various functions. 
     Referring to  FIG. 3 , the processor  140  of the network camera  200  according to the embodiment of the present invention may include a metadata generation unit  142  and a still image generation unit  144 . 
     Here, the processor  140  may be implemented to execute an instruction according to the code of the operating system and at least one program code included in the memory  130 , in this case, it can be understood that the components in the processor  140 , that is, the metadata generation unit  142  and the still image generation unit  144  distinguish and express different functions performed by the processor  140  according to a control instruction provided by a program code stored in the camera  200 . 
     The metadata generation unit  142  performs a function of generating video analysis information corresponding to the surveillance region of the camera in the form of text-based metadata. The metadata may include object detection information (movement, sound, invasion of a designated area, etc.) and object identification information (person, car, face, hat, clothes, etc.) photographed in the surveillance region, and detected location information (coordinates, size, etc.), and such metadata is transmitted to the video receiving device  300  through the network  200  in real time together with the video and audio signals detected in the surveillance region, and can be used for real-time control and video search. Therefore, it can be used to increase control convenience and search efficiency. 
     The processor  140  of the camera  200  according to an embodiment of the present invention may generate the text-based metadata, and capture and generate a still image for a specific analysis region among the video analysis information through the still image generation unit  144 . Further, the still image generated by the still image generating unit  144  may be stored in the memory  130 . 
     For example, the still image may be generated by cropping a specific region of the video data determined to be an identifiable object among the video data of the surveillance region detected for a specific region and a specific period. 
     More specifically, the still image may be a still image generated by cropping a specific region, that is, the video portion corresponding to an identifiable object detected within the surveillance region, among the video analysis information corresponding to the surveillance region written in the text-based metadata. 
     That is, it may be selected as a “best shot” still image that can recognize a specific object best among the video data photographed in the surveillance region, and it can be transmitted in real time together with the text-based metadata. Accordingly, a client such as the video receiving device  300  may use the still image as a thumbnail image when searching for video data transmitted without performing separate video processing, e.g., decoding. 
       FIG. 4  is a block diagram showing the configuration of the video receiving device shown in  FIG. 1 , and  FIG. 5  is a block diagram showing an embodiment of the internal configuration of the processor shown in  FIG. 4 . 
     The video receiving device  300  may receive and store data transmitted from the camera  200 , and perform the role of a client to analyze and monitor it. For example, the video receiving device  300  may be implemented as a DVR (Digital Video Recorder), a NVR (Network Video Recorder), a VMS (Video Management System), or the like, or as an application installed in a mobile terminal. 
     Referring to  FIG. 4 , Referring to  FIG. 5 , a video receiving device  300  according to an embodiment of the present invention includes a memory  310 , a database  320 , a processor  330 , a communication module  350 , and an input/output interface  340 . 
     The memory  310  is a computer-readable recording medium, and may include a non-volatile mass storage device such as a RAM, a ROM, and a disk drive. The memory  310  may store signals transmitted from the camera  100  shown in  FIG. 1 , for example, video data, audio data, still images, metadata, and the like corresponding to the surveillance region of the camera. 
     The database  320  may store and maintain unique information (e.g., camera ID, etc.) of the camera  100  illustrated in  FIG. 1 . That is, when the surveillance cameras connected to the video receiving device  300  are added and/or changed, information corresponding thereto may also be updated in the database  320 . 
     The processor  330  may be configured to process instructions of a computer program by performing basic arithmetic, logic, and input/output operations. The instruction may be provided to the processor  330  by the memory  310  or the communication module  350 . For example, the processor  330  may be configured to execute a received instruction according to a program code stored in a recording device such as the memory  310 . That is, the processor  330  may include a program module that is implemented by software such as C, C++, Java, Visual Basic, Visual C, and the like and performs various functions. 
     The communication module  350  may provide a function to communicate with the camera  100  through the network  200 . For example, a control signal, instruction, etc. provided under the control of the processor  330  of the video receiving device  300  may be transmitted to the camera  100  through the network  200  through the communication module  350 . Similarly, the photographed video information and/or location information generated by the camera  100  may be transmitted to the video receiving device  300  via the network  200 . 
     The input/output interface  340  may serve to provide an interface between an input device implemented as a keyboard or mouse and an output device such as a display. 
     Referring to  FIG. 5 , the processor  330  of the video receiving device  300  according to the embodiment of the present invention may include a metadata receiving unit  332 , a still image receiving unit  334 , and a thumbnail image generation unit  336 . 
     Here, the processor  330  may be implemented to execute an instruction according to the code of the operating system and at least one program code included in the memory  310 , at this time, it can also be understood the components in the processor  330 , that is, the metadata receiving unit  332 , the still image receiving unit  334 , and the thumbnail image generation unit  336  distinguish and express the different functions performed by the processor  330  according to a control instruction provided by a program code stored in the video receiving device  300 . 
     The metadata receiving unit  332  is a functional block corresponding to the metadata generation unit  142 , which is a functional block in the processor  140  of the camera  200  described in  FIG. 3 , and performs the function of receiving the text-based metadata generated and transmitted by the metadata generation unit  142 . For example, the metadata may be written in an XML format. 
     The metadata may include object detection information (movement, sound, intrusion into a designated area, etc.) and object identification information (person, car, face, hat, clothes, etc.) photographed in the surveillance region, and detected location information (coordinates, size, etc.), and such metadata is transmitted to the video receiving device  300  through the network  200  in real time together with the video and audio signals detected in the surveillance region, and used for real-time control and video search. Therefore, it can be used to increase control convenience and search efficiency. 
     Similarly, the still image receiving unit  334  is a functional block corresponding to the still image generation unit  144 , which is a functional block in the processor  140  of the camera  200  described with reference to  FIG. 3 , and performs a function of receiving the still image generated and transmitted by the still image generation unit  144 . For example, the still image may be generated by cropping a specific region of the video data determined to be an identifiable object among the video data of the surveillance region detected for a specific region and a specific period. More specifically, the still image may be a still image generated by cropping a specific region, that is, the video portion corresponding to an identifiable object detected within the surveillance region, among the video analysis information corresponding to the surveillance region written in the text-based metadata. That is, it may be selected as a “best shot” still image capable of recognizing a specific object best among the video data photographed in the surveillance region. 
     The thumbnail image generation unit  336  performs the function of generating a thumbnail image using the still image received through the still image receiving unit  334  when searching for video data corresponding to the surveillance region transmitted from the camera  200 . 
     That is, a client such as a video receiving device generates the still image as a thumbnail image and displays it, so that the image can be utilized when playing back the transmitted video data of the surveillance region. More specifically, the client may display the video analysis information transmitted in the form of text-based metadata received through the metadata receiving unit  332  based on the surveillance region, and display the “best shot” still image corresponding to the metadata information as a thumbnail image. 
     Through this, the client, such as a video receiving device, can efficiently use the client&#39;s resources by using the still image as the thumbnail image without performing a separate video decoding procedure, and as a result, the video data in the surveillance region can be more quickly and accurately searched. 
       FIG. 6  is a view showing an embodiment of performing real-time video streaming between a client and a server in an RTP standard, and  FIG. 7  is a diagram showing an example of media information responding between a client and a server through RTPS DESCRIBE in a network surveillance camera system according to an embodiment of the present invention. 
     In  FIGS. 6 and 7 , the RTP/RTSP streaming protocol is described as an example as a means for implementing real-time video streaming according to an embodiment of the present invention, but the real-time video streaming according to an embodiment of the present invention is not limited thereto. 
     As mentioned above, in the embodiment of the present invention, the camera  100  may serve as a server for transmitting data, and the video receiving device  300  may serve as a client for receiving the transmitted data. 
     Referring to  FIG. 6 , according to the RTSP protocol, in order to receive media data, the following procedure should be preceded. The RTSP address of the server  100  is obtained in the client  300 . In the client  300 , the step of obtaining the media type provided by the server  100  through the DESCRIBE instruction (S 111 ), the step of requesting the media provided by the server  100  through the SETUP instruction (S 112 ), the step of initializing an RTP session according to each media type in response to the SETUP (S 112 ), the step of determining and requesting media playback, playback speed, and playback time through the PLAY instruction (S 113 , S 114 , S 115 ), the step of temporarily stopping media transmission through the PAUSE instruction (S 118 ) and the step of terminating the RTSP session through the TEARDOWN instruction (S 119 ) are included. In order to perform real-time video streaming in the RTP standard between the client  300  and the server  100 , the step of retrieving the information of the media type provided by the server  100  through the DESCRIBE instruction (S 111 ) and the step of initializing the RTP session for each media type provided by the server  100  through the SETUP (S 112 ) should be sequentially performed. 
     As shown in  FIG. 6 , the embodiment of the present invention further includes the step of determining and requesting media playback, playback speed, and playback time through the PLAY instruction (S 113 , S 114 , S 115 ), the step of transmitting metadata (RTP Meta) (S 116 ) and the step of transmitting a still image (RTP Meta Image Stream) (S 117 ). 
     Referring to  FIG. 7 , this describes an example of the RTPS DESCRIBE response exchanged by the camera  100  for transmitting a still image in real time and the video receiving device  300  for receiving it in the relationship between the server and the client, respectively. As such, in the step of the client sending the RTSP DESCRIBE instruction to the server, a tag requesting generation of the metadata and still image, that is, a Require: Best Shot tag as shown as an example is added and transmitted. In this case, the RTSP server (e.g., the camera  100 ) that provides the above-described still image (e.g., Best Shot) generation and provision function may respond to the RTSP DESCRIBE instruction including the Require: Best Shot tag by displaying information in the meta image session, and accordingly, metadata and still images as well as video signals and audio signals (VIDEO+AUDIO+METADATA+JPEG still images) can be transmitted to the client (e.g., the video receiving device  300 ). 
     As another embodiment, when the client does not add the Require: Best Shot tag in the step of sending the RTSP DESCRIBE instruction to the server, same as before, the RTSP server (e.g., camera  100 ) may regard it as a client that does not support the meta image session, and transmit only the video signal and the audio signal excluding the metadata and the still image to the client (e.g., the video receiving device  300 ). 
       FIG. 8  is a diagram illustrating an example of an RTP header used in video streaming according to an embodiment of the present invention. 
     The RTP header used in video streaming according to the embodiment of the present invention includes an RTP extension header  1020  in addition to an RTP fixed header  1010  conforming to the RTSP standard. In this case, the description method of the RTP extension header  1020  may follow the RTP standard (rfc3550). As a preferred embodiment of the present invention, the RTP extension header  1020  may include, for example, an extension header ID, an object ID, and an extension field including coordinate information (location) and attribute information of the object. 
     Referring to  FIG. 8 , the extension header ID is “0xFFDD,” which is a header code for analyzing the still image syntax in the client. In addition, the object ID represents the identifier of the video analysis object described in the metadata written in XML. 
     Here, the still image and the metadata information, that is, the video analysis information, are related to each other (e.g., a mapping relationship of 1:1), and through the object ID field, the client can determine the still image (Best Shot) of an object detected in the metadata. 
     If the object ID is included in the RTP extension header  1020 , the best shot still image of the detected object can be acquired, but there may be a problem in that it is difficult to infer the relationship between the best shot still image and the original video image only with the object ID information. 
     Accordingly, in the embodiment of the present invention, the RTP extension header  1020  may include not only an object ID, but also an extension field including coordinate information (location) and attribute information of the object. 
     Specifically, the coordinate information (location) included in the extension field may be coordinate value information (e.g., x, y, width, height), at which the detected object is located in the corresponding original video region. 
     As described above, when the coordinate information (location) is further included in the RTP extension header  1020  in addition to the object ID, a function in that the region, in which the detected object is captured, is overlaid without additional metadata, to display it on the original video region can be implemented. 
     Also. the attribute information included in the extension field is information indicating attributes of the detected object. For example, the attribute information may be defined as a vehicle, a person, a face, a license plate, and the like. 
     As described above, if the attribute information is further included in the RTP extension header  1020  in addition to the object ID, additional video analysis functions can be implemented by selecting the attribute information in a client (e.g., video receiving device  300 ) side.  FIG. 9  is a diagram illustrating a method of operating a network surveillance camera system according to an embodiment of the present invention. A method for operating a network surveillance camera system according to an embodiment of the present invention will be described with reference to  FIGS. 1 to 9 . 
     A network surveillance camera system according to an embodiment of the present invention comprises the camera  100  for photographing a surveillance region to acquire a video and audio signal for the surveillance region, and a video receiving device  300  for receiving data transmitted by the camera  100  and storing and monitoring it. That is, in the embodiment of the present invention, the camera  100  may serve as a server transmitting data, and the video receiving device  300  may serve as a client receiving the transmitted data. 
     The camera  100  may be implemented as a network camera that performs an intelligent video analysis function. Accordingly, the camera  100  according to the embodiment of the present invention may generate the video analysis information corresponding to the surveillance region in the form of text-based metadata. For example, the metadata may be written in an XML format. 
     In the case of an embodiment of the present invention, the video analysis function of the camera  100  may be set through a protocol such as the HTTP interface provided by the camera  100 , and the value set at this time may be a surveillance region for video analysis, a type of identification target, and the like. As an example, it may be the coordinate information of the surveillance region, the type of an object to be video analyzed (e.g., car, person, bag, etc.), and the setting/confirmation of an object type analyzed as metadata. 
     The metadata may be generated in the form of text-based metadata, which may be written in, for example, an XML format. The metadata may include object detection information (movement, sound, intrusion into a designated area, etc.) and object identification information (person, car, face, hat, clothes, etc.) photographed in the surveillance region, and detected location information (coordinates, size, etc.). 
     While generating the text-based metadata, it is possible to capture and generate a still image for a specific analysis region among the video analysis information. For example, the still image may be generated by cropping a specific region of the video data determined to be an identifiable object among the video data of the surveillance region detected for a specific region and a specific period, and it may be implemented as a JPEG image file. 
     The object that is the target of the still image may correspond to the type of object included in the video analysis function of the camera  100  previously set. More specifically, the still image may be a still image generated by cropping a specific region, that is, a video portion corresponding to an object detected within the surveillance region, among the video analysis information corresponding to the surveillance region written in the text-based metadata. That is, it may be selected as a “best shot” still image capable of recognizing a specific object best among the video data photographed in the surveillance region. 
     In the embodiment of the present invention, in addition to the video data and audio data for the surveillance region photographed by the camera  100 , the above-described metadata and the corresponding still image are transmitted together to the client, that is, the video receiving device  300  in real time. 
     As an example, referring to  FIG. 7 , when the client adds Require: Best Shot and transmits it in the step of sending the RTSP DESCRIBE instruction to the server, in this case, the RTSP server providing the above-described still image (e.g., Best Shot) generation and provision function can transmit metadata and the corresponding still image to the client in addition to video data/audio data. 
     At this time, referring to  FIG. 8 , the RTP header according to the embodiment of the present invention includes the RTP extension header  1020  in addition to the RTP fixed header  1010  conforming to the RTSP standard, and the RTP extension header  1020  includes an extension header ID and an object ID. 
     Referring to  FIG. 8 , the extension header ID is “0xFFDD,” which is a header code for analyzing the still image syntax in the client. In addition, the object ID represents the identifier of the video analysis object described in the metadata written in XML. 
     Thereafter, as a client, the video receiving device  300  may receive data transmitted from the camera  100  in real time, analyze and monitor it, and for example, the video receiving device  300  may be implemented as a DVR (Digital Video Recorder), NVR (Network Video Recorder), VMS (Video Management System), etc., or as an application installed in a mobile terminal. 
     First, the video receiving device  300  receives the transmitted text-based metadata, and such metadata is transmitted together with the video and audio signals detected in the surveillance region to the video receiving device  300  through the network  200  in real time, and can be used for real-time control and video search to increase control convenience and search efficiency. 
     Similarly, the video receiving device  300  receives the transmitted still image, and the still image may be a still image generated by cropping a specific region, that is, a video portion corresponding to an identifiable object detected within the surveillance region, among the video analysis information corresponding to the surveillance region written in the text-based metadata. That is, it may be selected as a “best shot” still image capable of recognizing a specific object best among the video data photographed in the surveillance region. 
     In addition, the video receiving device  300  may generate a thumbnail image by using the still image and displays it when searching for video data corresponding to the surveillance region transmitted by the camera  200 , so that the image can be used to play back the transmitted video data of the surveillance area. More specifically, the video analysis information transmitted in the form of text-based metadata is displayed based on the surveillance region, and the “Best Shot” still image corresponding to the metadata information may be displayed as a thumbnail image. 
     Through this, the client, such as a video receiving device, can efficiently use the client&#39;s resources by using the still image as the thumbnail image without performing a separate video decoding procedure, and as a result, the video data in the surveillance region can be more quickly and accurately searched. 
     As described above, in the present invention, specific matters such as specific components, etc., and limited embodiments and drawings have been described, but these are only provided to help a more general understanding of the present invention, and the present invention is not limited to the above embodiments, and various modifications and variations are possible from these descriptions by those skilled in the art, to which the present invention pertains. 
     Therefore, the spirit of the present invention should not be limited to the described embodiments, and not only the claims described below, but also all equivalents or equivalent modifications to the claims belong to the scope of the spirit of the present invention. 
     According to this embodiment of the present invention, by providing a still image of an identifiable specific region among the video analysis information for the surveillance region, a client, such as a video receiving device, can search for the video data of the surveillance region more quickly and accurately by using the image information without performing a separate video decoding procedure. 
     In addition, when a client requests a video through the RTP/RTSP streaming protocol, the video analysis information implemented as text-based metadata by extending the existing RTP/RTSP streaming protocol and still images for the specific analysis region can be transmitted in real time in addition to the video/audio signal for the surveillance region.