Patent Publication Number: US-8976262-B2

Title: Methods of connecting network-based cameras to video stations, and corresponding video surveillance systems, video stations, and network-based cameras

Description:
FIELD OF THE INVENTION 
     This invention relates to video surveillance systems, particularly those with IP-based digital cameras and digital video recorders. 
     BACKGROUND OF THE INVENTION 
     Video surveillance systems play an important role in many different areas such as crime prevention, business management and traffic monitoring. Surveillance systems can be found almost everywhere such as banks, casinos, airports, military installations, and stores. 
     Due to better resolution and output quality, there is a growing trend of replacing analog cameras by digital cameras in the surveillance field. In a digital video surveillance system, network- or IP-based cameras are used instead of traditional analog cameras, which capture images and convert to digital formats right away and transmit the video data to a network-based video recorder (NVR) or video station over network, typically over ethernet under IP protocol. 
     Although these network- or IP-based surveillance systems are gaining popularity, there are some shortcomings. First of all, the installation of IP-based cameras is more complicated than analog cameras. The operator needs extensive network knowledge to configure each connected camera. Whenever there is a new camera connected to the system, the setup involves a lot more configuration changes than those of traditional analog surveillance system, for example prevention of conflicts of IP addresses. The second issue concerns security. Because video data from the IP-based cameras is sent over a shared network, hackers can easily access the cameras by connecting to the shared network and acquire the sensitive video data, or replace video images sent from the camera to the NVR. In fact there are tools readily available on the Internet for these.  FIG. 1  shows a possible scenario in which a hacker replaces video images sent from the camera to the NVR by using a computer with the same IP and MAC addresses of those of the IP-camera registered at the video station, which is generally known as “spoofing”. 
     Therefore, there is a need to devise more secure video surveillance systems that utilize network-based, or more specifically IP-based cameras, and NVR or video stations. 
     OBJECTS OF THE INVENTION 
     Therefore, it is an object of this invention to resolve at least one or more of the problems as set forth in the prior art. Particularly, it is an object of the current invention to provide video surveillance systems using network-based cameras and video stations with easier installation and/or improved security. As a minimum, it is an object of this invention to provide the public with a useful choice. 
     SUMMARY OF THE INVENTION 
     Accordingly, this invention provides a method of connecting at least one network-based camera to a video station, said video station having at least one socket for connecting said network-based camera. The method of this invention includes the steps of:
         a) sending a camera-advertising signal from the network-based camera to the video station for notifying the presence of the network-based camera, said camera-advertising signal includes a camera-identification tag for identification of the network-based camera;   b) if the network-based camera is in an unlock state, locking ownership of the network-based camera with the respective connected socket; and   c) if the network-based camera is in a lock state and is not locked by the respective socket, terminating connection between the network-based camera and the video station such that at any time, each of the at least one socket
           can lock ownership of only one network-based camera; and   receives video from the only one network-based camera with ownership locked by the respective socket.   
               

     Preferably, the method of this invention further includes the steps of:
         a1) after receiving the camera-advertising signal, determining whether the camera-identification tag is acceptable to the video station; and   a2) if the camera identification tag is not acceptable to the video station, terminating connection between the network-based camera and the video station.       

     Preferably, the steps b) and c) above include the steps of
         sending an ownership-locking-query signal from the video station to the network-based camera for querying whether ownership of the network-based camera with the respective connected socket can be locked;   after the network-based camera receives the ownership-locking-query signal,
           sending an accept-locking signal from the network-based camera to the video station if the network-based camera is in the unlock state; or   sending a reject-locking signal from the network-based camera to the video station if the network-based camera is in the lock state and is not locked by the respective socket;   
           if the accept-locking signal is sent from the network-based camera to the video station, locking ownership of the network-based camera with the respective connected socket and establishing a video connection for sending video from the network-based camera to the video station; and   if the reject-locking signal is sent from the network-based camera to the video station or if the camera-identification tag is not acceptable to the video station, terminating connection between the network-based camera and the video station.       

     More preferably, the ownership-locking-query signal includes a lock key for decrypting data transmission between the network-based camera and the video station. With the provision of the ownership-locking-query signal, the method of this invention may additionally further include the step of broadcasting a station-discovery signal from the video station before the camera-advertising signal is sent from the network-based camera to the video station, said station-discovery signal including a station-identification tag for the identification of the video station. Even more preferably, the ownership-locking-query signal further includes any one of the camera-identification tag, the station-identification tag, a set of assigned networking settings, or their combinations, and on this basis, the step of locking ownership of the network-based camera by the respective connected socket includes the steps of
         recording at least one of the following:
           recording the camera-identification tag at the respective connected socket; and   recording the station-identification tag at the network-based camera   
           selecting a set of unique networking settings at the video station as the assigned networking settings in the ownership-locking signal; and optionally, updating the network-based camera with the set of assigned networking settings.       

     Preferably, the camera-advertising signal further includes any one of a set of camera networking settings, camera-locking status, or their combinations. 
     Optionally, the method of this invention further including the steps of:
         sending a heart-beat signal from the network-based camera to the respective connected socket for maintaining ownership of the network-based camera with the respective connected socket; and   if the heart-beat signal is not received within a predetermined period of time, unlocking ownership of the network-based camera with the respective connected socket and terminating connection between the network-based camera and the respective connected socket.       

     Preferably, the network-based camera is connected to said at least one socket through a network cable. 
     It is another aspect of this invention to provide a video surveillance system having at least one network-based camera and a video station incorporating any one of the above methods. 
     It is yet another aspect of this invention to provide a method of controlling connection between at least one network-based camera to a video station, in which a camera-advertising signal is sent from the network-based camera to the video station for notifying the presence of the network-based camera. The camera-advertising signal includes a camera-identification tag for identification of the network-based camera, said video station having at least one socket for connecting said network-based camera. The method includes the steps of:
         1) if the network-based camera is in an unlock state, locking ownership of the network-based camera with the respective connected socket; and   2) if the network-based camera is in a lock state and is not locked by the respective socket, terminating connection between the network-based camera and the video station    such that at any time, each of the at least one socket
           can lock ownership of only one network-based camera; and   receives video from the only one network-based camera with ownership locked by the respective socket.   
               

     It is a further aspect of this invention to provide a video station for a video surveillance system incorporating the above method. 
     This invention further provides a method of connecting at least one network-based camera to a video station, said video station:
         having at least one socket for connecting said network-based camera,   can locking ownership of the network-based camera with the respective connected socket if the network-based camera is in an unlock state, and provide the network-based camera with a lock key for decrypting data transmission between the network-based camera and the video station and   can terminate connection between the network-based camera and the video station if the network-based camera is in a lock state and is not locked by the respective socket   and the method includes the steps of:   a) sending a camera-advertising signal from the network-based camera to the video station for notifying the presence of the network-based camera, said camera-advertising signal includes a camera-identification tag for identification of the network-based camera;   b) recording the lock key at the network-based camera if an ownership-locking-query signal from the video station is received, and the network-based camera is in a unlock state   such that at any time, each of the at least one socket
           can lock ownership of only one network-based camera; and   receives video from the only one network-based camera with ownership locked by the respective socket.   
               

     It is another aspect of this invention to provide a network-based camera for a video surveillance system incorporating the above method. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Preferred embodiments of the present invention will now be explained by way of example and with reference to the accompanying drawings in which: 
         FIG. 1  shows how fake video images can be sent to a video station by “spoofing”; 
         FIG. 2  shows the general system architecture of the video surveillance system of the current invention; 
         FIG. 3  shows the flow chart of how a network-based camera is locked by one socket of the video station of this invention; 
         FIGS. 4   a  to  4   d  show the flow charts of the processes involved in the network-based camera for controlling its connection with the video station; and 
         FIGS. 5   a  to  5   f  show the flow charts of the processes involved in the video station for controlling the connection of one socket with the IP-based camera. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     This invention is now described by way of examples with reference to the figures in the following paragraphs. Objects, features, and aspects of the present invention are disclosed in or are apparent from the following description. It is to be understood by one of ordinary skilled in the art that the present discussion is a description of exemplary embodiments only, and is not intended as limiting the broader aspects of the present invention, which broader aspects are embodied in the exemplary constructions. List 1 is a list showing the parts and respective reference numerals in the figures. 
     
       
         
           
               
            
               
                   
               
               
                 List 1 
               
            
           
           
               
               
            
               
                 Reference numeral 
                 Part name 
               
               
                   
               
               
                 10 
                 video surveillance system 
               
               
                 12 
                 network-based camera 
               
               
                 14 
                 video station 
               
               
                 16 
                 socket 
               
               
                 20 
                 video recorder 
               
               
                   
               
            
           
         
       
     
     Referring to  FIG. 2 , the video surveillance system  10  has two components, at least one network-based camera  12 , and at least one video station  14 . The video station  14  has at least one socket  16  for connecting to the network-based camera  12 , and a video recorder  20 . The video surveillance system  10  can have as many network-based cameras  12 , video stations  14 , and sockets  16  as desired, which is to be determined according to the usage of the video surveillance system  10  depending on various factors including the area to be covered, complexity of the venue, and so on, subject to resources available. The sockets  16  in the context of this invention refer to physical sockets that can connect with the network-based cameras  12  physically, for example through a wired connection. The sockets  16  are not virtual sockets in typical networking that connect to various network devices. The video station  14  is connected to the internet, monitoring device, and storage if desired with known technologies, for example RJ-45 sockets and cables, VGA or HDMI sockets and cables, USB, IEEE1394 or eSATA sockets and cables. 
     The network-based cameras  12  and the video station  14  are each implemented with suitable software control modules, for example in the form of software, for controlling their connections. These will be described in detail in the following paragraphs. 
       FIG. 3  shows a flow chart explaining how a network-based camera  12  is locked by one socket  16  of the video station  14  of this invention. When a network-based camera  12  is connected to one socket  16 , a camera-advertising signal is sent from the network-based camera  12  to the video station  14  for notifying the presence of the network-based camera  12 . This camera-advertising signal includes a camera-identification tag for identification of the network-based camera  12 . This camera-identification tag can be any desirable unique code that can identify individual network-based camera  12 , preferably at hardware level for example production serial number of the network-based camera  12 . If the network-based camera is in an unlock state, ownership of the network-based camera  12  is locked with the respective connected socket  16 . If the network-based camera  12  is in a lock state and is not locked by the respective socket, connection between the network-based camera  12  and the video station  14  is terminated. 
     Before the network-based camera  12  enters the lock state, the camera-advertising signal can be sent by the network-based camera  12  actively, that is, can be sent periodically regardless whether the network-based camera  12  detects connection with the socket  16 , or even whether the network-based camera  12  detects connection to a network. Alternatively, the camera-advertising signal can be sent by the network-based camera  12  passively, that is, can be sent only when the network-based camera  12  detects connection with the socket  16 , or when the network-based camera  12  detects connection to a network. 
     Optionally, after receiving the camera-advertising signal, the video station  14  then determines whether the camera-identification tag is acceptable to the video station  14 , for example, by checking whether the camera-identification tag is contained in a list, which can be stored in the video station  14  or accessible to the video station  14  through a network connection. If the camera-identification tag is acceptable to the video station and, as described above, if the network-based camera is in an unlock state, ownership of the network-based camera  12  is locked with the respective connected socket  16 . Otherwise, if the camera-identification tag is not acceptable to the video station, connection between the network-based camera  12  and the video station  14  is terminated. 
     Other than the camera-identification tag, the camera-advertising signal can optionally contain a field indicating the locking status of the network-based camera  12 , i.e. indicating whether the network-based camera  12  is in lock or unlock state for connection to the a socket of the video station  14 . This is desirable as the video station can immediately determine whether the ownership of the network-based camera  12  with the respective connected socket  16  can be locked, or connection with the network-based camera  12  with the video station  14  should be determined. 
     If the video station  14  is not aware of the locking state of the network-based camera  12 , for example from the camera-identification tag, then the following processes are applicable. Specifically, an ownership-locking-query signal is sent from the video station  14  to the network-based camera  12  for querying whether ownership of the network-based camera  12  with the respective connected socket  16  can be locked. After the network-based camera  12  receives the ownership-locking-query signal, if the network-based camera  12  is in an unlock state, an accept-locking signal is sent from the network-based camera  12  to the video station  14 , the ownership of the network-based camera  12  with the respective connected socket  16  is then locked and a video connection is established for sending video from the network-based camera  12  to the video station  14 . Otherwise, if the network-based camera  12  is in a lock state and is not locked by the respective socket, a reject-locking signal is sent from the network-based camera  12  to the video station  14 , and connection between the network-based camera  12  and the video station  14  is terminated. The connection between the network-based camera  12  and the video station  14  is also terminated if the camera-identification tag of the network-based camera  12  is determined to be unacceptable to the video station  14 . Through the above operations, each of the socket  16  can lock ownership of only one network-based camera, and receives video from the only one network-based camera with ownership locked by the respective socket. Having said the above, the above processes can still be implemented if the video station  14  is aware of the locking state of the network-based camera  12  as back up. It should be note that while the network-based camera  12  is in a lock state, the respective connected socket  16  may still send the ownership-locking-query signal to the network-based camera  12 , for example, for updating the network settings, the lock key, or any necessary settings. In such a case, the reject-locking signal, which will terminate connection between the network-based camera  12  and the video station  14 , should not be sent. 
     Optionally, a station-discovery signal can be broadcasted from the video station  14  before the camera-advertising signal is sent from the network-based camera to the video station  14 . In such a case, a camera-advertising signal can be sent after receiving the station-discovery signal. This station-discovery signal includes a station-identification tag for the identification of the video station  14 . This station-identification tag can be any desirable unique code that can identify individual video station  14 , preferably at hardware level for example production serial number of the video station  14 . The use of this station-identification tag will be explained later. 
     Other than the camera-identification tag, the ownership-locking-query can also include a lock key for decrypting data transmission between the network-based camera  12  and the video station  14 . All data transmission including video and various control messages including the heart-beat signals. However, preferably only the control messages are encrypted so as to reduce network overhead and processing power requirements at the network-based camera  12  and the video station  14 . Various encryptions can be used, for example RC4 (http://en.wikipedia.org/wiki/RC4), WEP (http://en.wikedia.org/wiki/Wired Equivalent Privacy), and DES (http://en.wikipedia.org/wiki/Data Encryption Standard). The lock key can be generated by various methods, for example UUID (http://en.wikipedia.org/wiki/UUID) or OUI (http://en.wikipedia.org/wiki/Organizationally Unique Identifier), which can be generated on-demand or stored in the video station  14 . Generation of the lock key in the video station  14  on-demand is more preferred as this would be less prone to security breach. 
     Additionally, the ownership-locking-query signal can further include any one of the camera-identification tag, the station-identification tag, a set of assigned networking settings, or their combinations. The camera-identification tag can serve for additional checking purpose, while the use of the station-identification tag and the set of assigned networking settings will be described later. 
     The “locking” of the ownership of the network-based camera  12  with the respective connected socket  16  can be implemented in various different manners. For example, the network-based camera  12  and the connected socket  16  may each be associated to a virtual electronic locking status which can be in either “unlock” or “lock”, for which this virtual electronic status can be as simple as a true/false field. During the locking of the ownership, the respective locking status of the network-based camera  12  and the connected socket  16  is updated to “lock”. To enhance security, it is even more preferred that the video station  14  selects a set of unique networking settings as the set of assigned networking settings in the ownership-locking-query signal, such that the networking settings of the network-based camera  12  can be updated during the locking process. The selection and updating of the network settings, which may include IP address, subnet mask, DNS server address, and so on can follow the standard DHCP procedures or static IP assignment procedures. 
     Optionally the camera-identification tag is recorded at the video station  14  and/or the station-identification tag is recorded at the network-based camera  12  during locking of the ownership. This can be useful to enhance subsequent checking capabilities and security. In order to ensure that the connection between the network-based camera  12  and the video station  14  is intact after some time, it is preferred to send a heart-beat signal from the network-based camera  12  to the video station  14 . If this heart-beat signal is not received in a predetermined period of time, say every 5 to 30 seconds, then the ownership of the network-based camera  12  and the respective connected socket  16  changes to “unlock”, i.e. the virtual electronic locking status of the network-based camera and the connected socket  16  is changed from “lock” to “unlock”. The change of the locking status can be done by internal checking for example as in the case of using the heart-beat signal, or by sending a unlock signal to the network-based camera  12  and/or the connected socket  16  under user control. If the camera-identification tag is recorded at the video station  14  and/or the station-identification tag is recorded at the network-based camera  12 , these tags can act as extra checking for the security of the connection, for example, in preventing spooling as these tags are associated to the network-based camera  12  and the video station  14  at hardware level. The handling of heart-beat signal is known in the field and will not be further described. 
     It should be noted that the “locking” of the ownership is done between the network-based camera  12  with the respective connected socket  16 , but not between the network-based camera  12  with the video station  14 . One consequence of this is that at any time, each of the at least one socket can lock ownership of only one network-based camera, and receives video from the only one network-based camera with ownership locked by the respective socket. That is, even if a network switch or repeater with multiple network ports is connected to a socket  16  of the video station  14 , and each of these multiple network ports is connected to one network-based camera  12 , only one of these network-based cameras  12  is able to engage with the socket  16  into the “locking” relationship and therefore only video from this “locked” network-based camera  12  is received by the socket  16 . Preferably, the locked socket  16  stops looking for unlock network-based camera  12 , for example stops sending the station-discovery signal, once the socket  16  enters into the lock status. This is different from the current approach which generally utilizes DHCP as the network connection setup protocol, which allows multiple cameras to be connected to a single network socket on existing video stations. Such current approach at least has the problem of quality drop if too many cameras are connected to a single socket. 
     The network connection between the socket  16  and the network-based camera  12  can be wireless or wired. In the case of wireless connection, where there are typically multiple channels, each physical socket  16  can allow connection for one channel only so as to achieve the effect that one socket  16  locks ownership of only one network-based camera  12 , and receive video from the only one network-based camera  12  with ownership locked by the respective socket  16  at any time. However, wired connection is preferred which can further enhance the security of the video surveillance system  10 . As the socket  16  of the current invention can now engage into “locking” relationship with only one network-based camera  12  with camera-identification tag acceptable to the video station  14 , and preferably with the lock key, wired connection can substantially reduce the chance of “spoofing”, as the network-based camera  12  can then be traced physically by the wired connection. By contrast, current network-based video surveillance systems utilize network-based cameras, which allow multiple cameras to be connected to one socket, and/or do not use a lock key sent from the video station  14  as in the current invention. Accordingly, the chance of spoofing is higher, and it can be difficult to trace the actual physical location of the network-based camera. 
     As one socket  16  can now connect to one network-based camera  12  only, the setting up of the system is simpler than currently available network-based video surveillance systems, which allow multiple cameras to be connected to one socket. 
       FIGS. 4   a  to  4   d  show exemplary flow charts of the processes involved in the network-based camera  12  for controlling the connection with the video station  14  that has implemented all of the above optional components of the video surveillance system  10  of this invention. Specifically,  FIG. 4   a  shows the control of the locking status at the network-based camera  12 , in which the network-based camera  12  goes to unlock state during initialization after checking that the network-based camera  12  is ready for network connection. If the ownership-locking-query signal message is received and the network-based camera  12  is in the unlock state, the network-based camera  12  then updates itself to lock state. This status is changed back to “unlock” if an unlock signal is received, network is lost or not ready as shown in  FIG. 4   b , or there is no response to the heart-beat signal sent by the network-based camera  12 . Monitoring of the network status can be done by protocols like the Auto-negotiation of Ethernet Physical Layer Communication (http://en.wikipedia.org/wiki/Autonegotiation). 
       FIG. 4   c  shows various processes involved when the network-based camera  12  is in the unlock state, including
         sends the camera-advertising signal ADVERTISE from the network-based camera  12 , and then waits for signals from the socket  16  of the video station  14 ;   if a message targeting the network-based camera  12  is received from the socket  16 , and if this message is the ownership-locking-query signal LOCK, and if the network-based camera  12  is in the unlock state, the network-based camera  12  changes it status to the lock stage, updates its network settings, stores the lock key for subsequent data decryption, and sends an accept-locking signal ACCEPT LOCK to the socket  16  of the video station  14 ;   the network-based camera  12  will go to the state of waiting message from the socket  16  if one of the following happens:   1. no message is received from the socket  16 ;   2. message from the socket  16  is not intended for the network-based camera  12 ;   3. the ownership-locking-query signal LOCK is sent from the socket  16  but the network-based camera  12  is in the lock state;   if the network-based camera  12  is in the lock state and if an “unlock” message is received containing correct information, for example the correct camera-identification and station-identification tags, the network-based camera  12  updates its locking status to “unlock”   at all times, the network status is monitored, as described above.       

       FIG. 4   d  shows processes for monitoring the network status as above, and various processes involved when the network-based camera  12  is in the lock state, including the handling of the maintenance of “heart-beat” between the network-based camera  12  and the respective connected socket  16 . As stated above, as these processes are known to the field, these processes will not be further described 
       FIGS. 5   a  to  5   f  show exemplary flow charts of the processes involved in the video station  14  for controlling the connection with the network-based camera  12  that has implemented all of the above optional components of the video surveillance system  10  of this invention. Specifically,  FIG. 5   a  shows the control of the locking status at each socket  16  of the video station  14 , in which the socket  16  goes to unlock state during initialization after checking that the socket  16  is ready for network connection. The socket  16  goes into the lock state if the socket  16  is in an unlock state and receives an accept-locking signal from the network-based camera  12 . The socket  16  goes into the unlock state if one of the following happens:
         1. the network-based camera is detected to be not connected to the socket  16 ;   2. a reject-locking signal REJECT is received;   3. no heart-beat signal HEART-BEAT is received from the network-based camera  12  within a predetermined period of time.       

       FIG. 5   b  shows that the socket  16  goes to unlock state during initialization.  FIG. 5   c  shows the processes involved in the unlocking of the socket  16 , which is triggered by the disconnection of the network-based camera  12  from the socket  16  at hardware level. 
       FIG. 5   d  shows various processes involved when the socket  16  of the video station  14  is in the state of detecting presence of network-based camera  12 , including
         waits for the camera-advertising signal ADVERTISE from the network-based camera  12 ;   if the socket  16  receives the camera-advertising signal ADVERTISE from the network-based camera  12 , and if this signal indicates that the network-based camera  12  is unlock, then the video station  14  can allocate or assign a set of unique network settings. The ownership-locking-query signal LOCK can then be generated and sent to the network-based camera  12  for locking the ownership with the connected socket  16 ;   the station-discovery signal DISCOVERY will be sent periodically if there is no response from the connected network-based camera  12 , or if there is no connection to any network-based camera  12  at all;   at all times, the connection status at hardware level is monitored, as described above.       

       FIG. 5   e  show various processes involved after the ownership-locking-query signal LOCK is sent from the socket  16  to the network-based camera  12 , including:
         waits for the accept-locking signal ACCEPT LOCK or rejecting-locking signal REJECT from the network-based camera  12 ;   checks whether the accept-locking signal ACCEPT LOCK or rejecting-locking signal REJECT is from the target camera, for example, by comparing whether the camera-identification tag in this signal corresponds to that in the earlier sent ownership-locking-query signal;   if the signal is from the target camera, and if the signal is the accept-locking signal ACCEPT LOCK, connection with the network-based camera is established, and the socket  16  goes into the lock state with the network-based camera  12 ;   connection with the network-based camera  12  is terminated if one of the following happens:
           i. the signal is the reject-locking signal REJECT;   ii. the network-based camera  12  is disconnected; or   iii. the heart-beat maintenance processes resulted in a timeout;   
           the station-discovery signal DISCOVERY will be sent periodically if there is no response from the connected network-based camera  12 , or if there is no connection to any network-based camera  12  at all;   at all times, the connection status on hardware level is monitored, as described above.       

       FIG. 5   f  describes the processes when the lock relationship is established between the network-based camera  12  and the socket  16 , including various processes for handling the heart-beat signal maintenance between the network-based camera  12  and the socket  16 . These processes are known in the field and are self-explanatory. 
     It will be apparent to the skilled persons that the above processes are implemented on the respect network-based camera  12 , the socket  16 , and the video station  14  as software programs, and a skilled programmer would be able to produce appropriate software codes based on the current description and flow charts in the figures. Existing network-based camera  12 , the socket  16 , and the video station  14  with suitable hardware configuration with respect to processing power, storage, network connection capabilities implemented with processes of the current invention described herein in the form of software can practice the current invention. When performing the processes of the current invention, the processor will perform different functions at different times depending on which process is taking control of the processor at that time. That is, the processor is acting as various virtual devices each carrying out different processes of the current invention, for example a camera-advertising signal generator when the camera-advertising signal is sent from the network-based camera  12 ; a camera-identification tag acceptance determining device when determining whether the camera-identification tag is acceptable to the video station; locking status updater when the ownership of the network-based camera is to be locked with the respective connected socket  16 ; and so on. 
     While the preferred embodiment of the present invention has been described in detail by the examples, it is apparent that modifications and adaptations of the present invention will occur to those skilled in the art. Furthermore, the embodiments of the present invention shall not be interpreted to be restricted by the examples or figures only. It is to be expressly understood, however, that such modifications and adaptations are within the scope of the present invention, as set forth in the following claims. For instance, features illustrated or described as part of one embodiment can be used on another embodiment to yield a still further embodiment. Thus, it is intended that the present invention cover such modifications and variations as come within the scope of the claims and their equivalents.