METHOD AND SYSTEM FOR VIDEO MONITORING

Abstract: A system and method for monitoring a site from a remote location transmits a video picture generated at the site to the remote location. A video signal is generated from a video camera located at the site. A connection is established between the site and a display device at the remote location in response to a request signal and video is transferred over the connection. In response to control signals received from the display device, a portion of the video signal is transferred to the display device. The portion includes the video generated at the time of the request signal and prior to the request signal.

Description: METHOD AND SYSTEM FOR VIDEO MONITORING TECHNICAL FIELD This invention relates generally to methods and systems for providing remote video communications A particular aspect of the present invention relates to a method and system for monitoπng a site using a camera located at the site In general, remote video systems provide visual communication between a central location and a person at a different location An exemplary application of such remote video systems is a secuπty system for protecting the location using a video camera which provides still or video image signals of the premises Because of the bandwidth generally required for transmitting video signals, substantial network connection charges may be incurred if the video signal is continuously transmitted Therefore, a network connection and transmission of video image signals is not earned out before it is necessary A number of different detectors are utilized in the monitored site for providing information about vaπous conditions at the site If the information received from the monitored site is such that further efforts may be needed, an alarm signal is sent to a secuπty guard or central alarm station Upon receipt of the alarm signal, a direct connection may be initiated and a still or video image signal of the monitored site then transmitted to the central alarm station or to a person at a remote location Such a conventional video monitoπng method and system has at least the following drawbacks If the video picture is sent to a secuπty guard at a stationary remote location, the viewed on-line \ideo is usually not the most interesting picture or does not show the reason for the alarm Instead, it is a picture transmitted soon after the alarm was sent Therefore, the transmitted picture might not show what happened when the alarm was initiated This is especially problematic if the secuπty guard is in a motor vehicle vehicle on the road or otherwise without a direct connection to the monitored site, since there might be some significant delays in forwarding the video signal to the guard using conventional wireless networks Consequently, the conventional methods and systems have a problem of how to send the picture so that a guard or other person can see what happened just when the alarm was generated There is also a problem of how to send a satisfactory picture to a mobile terminal without incurπng undesireable delays, errors, dropped frames, etc DISCLOSURE OF THE INVENTION The present invention thus addresses video monitoπng systems which are disadvantageous for at least the reasons recognized above In particular, the present invention is directed to a method and system for video monitoπng in which a person at a remote location is put into communication with a monitored site The present invention also allows those persons at remote locations to engage in control of the video signal and other services when they are connected For example, a secuπty guard on the road can control the video signal using rewind and forward functions so that it shows the reason for the connection A video segment can be selected which includes the video at the time of the connection and a small before the connection An exemplary embodiment of the present invention is directed a system and method of monitoπng a site from a remote location transmits a video picture generated at the site to the remote location A video signal is generated from a video camera located at the site A connection is established between the site and a display device at the remote location in response to a request signal and video is transferred over the connection In response to control signals received from the display device, a portion of the video signal is transferred to the display device. The portion includes the video generated at the time of the request signal and pπor to the request signal BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a generalized block diagram illustrating the major elements of a video monitoπng system according to an exemplary embodiment of the invention Fig. 2 is an illustration of a display device used in the exemplary embodiment shown in Fig. 1. Fig. 3 is a flowchart illustrating a method of providing a video signal according to an exemplary embodiment of the invention. BEST MODE FOR CARRYING OUT THE INVENTION The foregoing and a better understanding of the present invention will become apparent from the following detailed descπption of example embodiments and the claims when read in connection with the accompanying drawings, all forming a part of the disclosure of the invention. While the foregoing and following wπtten and illustrated disclosure focuses on disclosing example embodiments of the invention, it should be clearly understood that the same is by way of illustration and example only and is not to be taken by way of limitation, the spiπt and scope of the present invention being limited only by the terms of the claims in the patent issuing from this application. An exemplary embodiment of the present invention seeks to provide a method of video monitoring a central location in which some degree of control over the video monitoπng can be performed by a person at a remote location. One possible application of the exemplary embodiment of the invention is a secuπty system in which the video signal from a surveillance camera at a physical site may be connected with a person at a remote location upon an alarm signal or other event and the video can be controlled by the person at the remote location in order to concentrate attention on a time peπod of the video signal The invention of course is not limited to such exemplary embodiment It is more broadly directed to a diverse set of different video monitoπng methods and system Alarm Site Monitoπng System As shown in Fig 1 , a video monitoπng system 100 has an alarm site 101 m which there are one or more different detectors 102, - 102 n as known in the art for providing respective alarm signals 103, - 103n A video camera 104 provides a video signal showing the site There may also be additional individual video cameras (not shown) for providing respective video signals of different portions of alarm site 101 or from a different viewing perspective The video camera 104 may be of any suitable type, including a surveillance camera The video signal can be forwarded to a recording device 105, forwarded to an external feed 106, or split and forwarded to both In the exemplary embodiment, a video server is provided at the alarm site to both store the video signal and transmit it to remote locations Although the video camera is constantly providing a video signal in the exemplary embodiment, it may alternatively be activated in response to an alarm or other control signal The video signal may be of a standardized broadcast video format such as NTSC or PAL, or it may be of another video format presently existing or hereinafter developed for surveillance or other relatively low bandwidth signals As used in this application, the term video signal includes signals having only pictoπal information as well as signals having both pictoπal information and audio corresponding in time with the pictoπal information There may or may not be a real-time compression unit or encoder integrated as part of the video camera In either case, the compressed data stream can be immediately packetized and transferred to switching system 107 However, the compressed data is preferably recorded and stored locally (in the alarm site) for later transfer to switching system 107 In the case of a video signal with associated audio, the audio information is interleaved with the pictoπal information into a single bitstream. In an alternative embodiment of the invention, the video camera 104 may be a digital video camera used in conjunction with a personal computer or another camera conventionally used in conjunction with a computer terminal, such as, for example, an automated teller machine (ATM). The camera can be attached to, located nearby or enclosed within the personal computer or computer terminal. The video signal generated by such a camera may be in a format more easilyprocessed by a personal computer, such as MPEG-2, MPEG-3 or MPEG-4, rather than in a NTSC, PAL or surveillance camera format. Video Compression In the exemplary embodiment, it is expected that the video signal provided by camera 104 will have to be compressed internally or externally since many of the transmission channels are narrowband channels with low bit rates. For example, internet connections are usually limited to about 56 kilobits per second. Therefore, a high degree of compression is necessary for the video to be transmitted over those channels The video of the resulting compressed data stream will have a resolution of about 176 x 144 pixels and a frame rate of up to 15 Hz. Although the compression process is somewhat computationally intensive, the decompression process at the receiving end of the transmission is much less intensive and amenable to devices, such as mobile stations, with relatively low computational power. If camera 104 is not configured to provide a low bit rate video signal, a separate video compression unit located at the alarm site, such as an ITU-T H.261, H.263 or MPEG 4 encoder, compresses the video signal from video camera 104 According to these compression techniques, each frame of the video signal will have a time stamp associated with it Other low bandwidth compression systems may also be used See, for example, "Solution for low bit-rate video coding" by M Karcewicz et al, Advance. Vol 8, September 1997 Since many applications of the invention in a secuπty environment will emphasize surveillance, the compression process may utilize a motion-sensitive vaπable compression algoπthm providing a high degree of compression in the absence of movement in the picture and a low degree of compression in the presence of movement Video Server A vanety of arrangements can be made for recording the video at the alarm site In the exemplary embodiment, recording device 105 is a video server which stores the video signal from camera 104 in a large capacity video database and then provides the video for later transmission upon demand It is also configured to receive the vaπous alarm signals from the detectors at the alarm site When the video signal is transferred by the server as descπbed below in response to an alarm, data indicating the time of the alarm and the correspondence between frames of the video signal and the time of said alarm is included in the video signal The server is preferably a dedicated video se er capable of transmission over HTTP, TCP and UDP protocols In the case of UDP, the server packetizes the video signal from the camera in order to enable recovery from packet losses duπng wireless transmission The server can preferably adjust the video signal (by changing the resolution and/or frame rate) to best suit the available network bandwidth and avoid congestion and loss of video in any particular connection In particular, as explained below the server supports a vaπety of controls over the part of the \ideo signal transmitted utiling fast-forward and fast-rewmd operations The server may support real-time v ideo streaming of the video as well as this store and forward serving of video Preferably, the server utilizes a buffer for temporaπly stoπng the most recent portion of the video signal received from camera 104 In response to an alarm signal, the buffered video signal can be transmitted more quickly than a video signal stored in the large capacity video database Rather than a dedicated video server, a web server can be used to transmit video over HTTP Although less expensive, such a server is disfavored since flow control such as fast-forward and rewind can typically only be accomplished with advanced and complicated programming Transmission of Video Signal The video signal from video camera 104 at alarm site 101 is provided to switching system 105 of a network (other elements of the network are not shown for the sake of simplicity) such as the public service telephone network (PSTN) Alternatively, the switching system can have some intelligence and functionality built into it for performing the functions of the video unit The video signal can be bi- directionally transferred between switching system 105 and public land mobile network (PLMN) 106. A wireless link can be established between PLMN 106 and a mobile station (shown as being implemented in a motor vehicle 107 in the exemplary embodiment of Fig 1 ) to forward the video signal to the mobile station The video signal can also be forwarded, for example, from switching system 105 to a stationary computer, including monitor, 109 via the internet 108 While certain devices are used in the exemplary embodiment, any suitable device, either presently existing or hereafter developed, may be utilized to receive and display the video As discussed herein, the client can be a standalone, dedicated, device or can have the functionality embedded within other communications technology such as a web browser In the exemplary embodiment using a server at the monitored site, the stationary computer or mobile station can interact with the server using client-server connections In a PSTN network, the connections are conventional point-to-point switched connections The video is transferred from the server in the monitored site to the client through the network In the reverse direction, the client (computer, mobile station, or other suitable device) can control some operations of the server using control protocols The client can, for example, control some parameters of the connection, such as bit rate, degree of eπor correction, etc In particular, in the exemplary embodiment, the server is configured to allow each respective client to designate parameters of the connection in order to optimize the communication link to compensate for the communication medium For example, the exemplary embodiment of Fig 1 shows an internet connection to a computer and wireless connection to a mobile station Signals can be sent from the computer to the switching system, either directly as shown in the exemplary embodiment of Fig. 1 , or through internet 108 Each of these communication links have significantly different characteπstics and the video transmission is controlled accordingly Internet Video Transmission The internet uses transmission control protocol (TCP) transport layer in which packets dropped duπng transmission are retransmitted Thus, a client receiving the video signal via the internet must deal with the fact that the channel throughput may be highly vaπable due to TCP packet retransmission The video can either be entirely downloaded first and then displayed, displayed after some buffeπng is done to control the transmission rate, or streamed despite errors, dropped frames, or pauses in the video UDP introduces relatively stable throughput, but also the possibility of packet losses Consequently, the client must be able to recover from packet losses and possibly conceal the lost video content Despite the concealment, the quality of the reconstructed video suffers somewhat On the other hand, the playback of the clip is hkelv to happen in real-time without annoying pauses Also, a computer of a secuπty agency may utilize a firewall which do not permit UDP, in which case, adjustments have to be made for UDP As specific examples of internet video systems, RealSystem G2™ from RealNetworks and NetShow 3.0 or 4.0 from Microsoft may be used RealSystem uses the Real Time Streaming Protocol (RTSP) and data, such as time of the alarm, location, etc , can be sent along with the video information. This data can be displayed along with the video. The client terminal may consist of a personal computer (PC) It should be capable of communicating with the server through the internet and over a network such as, for example, the public service telephone network (PSTN) Wireless Video Transmission Communication links in wireless cellular networks can expeπence high amounts of eπor, loss of signal strength, etc., not found in wired networks. In addition to histoπcally low bit rates for data communication, these disadvantages have conventionally rendered video transmission in a wireless cellular network a practical impossibility However, newly developed networks such as the Global System for Mobile Communications (GSM) phase 2+ in Europe and the Universal Mobile Telecommunication System (UMTS) have increased the data rates to such an extent that the quality of video signals can be made acceptable. Video transmission can be earned out using, for example, High- Speed Circuit Switched Data (HSCSD) and General Packet Radio Services (GPRS). HSCSD offers two basic connection types, namely transparent and non-transparent, distinguished by their way of correcting transmission eπors In a transparent connection, eπor corection is done entirely by a forward eπor correction mechanism Consequently, the available throughput is constant and the transmission delay is fixed, but the transmitted data are likely tocontain bit inversion eπors. In the non-transparent approach, the Radio Link Protocol (RLP) is used to provide retransmission in case of detected eπors in the receiving end. Consequently, a non-transparent connection is eπor free, but through put and transmission delay is varying. UDP over transparent HSCSD introduces bit eπors in addition to possible packet losses. However, UDP can detect and indicate these bit eπors. The eπoneous packets can then be discarded in the receiving end. However, the decoders might utilize the eπoneous data in concealment and it might be worthwhile to try to decode the eπoneous packets, too. UDP over non-transparent HSCSD is free of bit eπors but introduces varying delay due to retransmission. Thus, this approach is likely to perform worse than UDP over transparent HSCSD. In the TCP over transparent HSCSD approach, the unit to retransmit is a TCP packer, whereas in the TCP over non-transparent HSCSD approach, the unit to retransmit is a GSM frame. Since a GSM frame contains fewer bits than a TCP packet, the retransmission of a TCP packet is likely to cause retransmission of already coπectly transmitted data therefore reducing the channel throughput. Thus, the exemplary embodiment uses TCP over non-transparent HSCSD. GPRS is a packet switched data service. It provides multiple Quality of Service (QoS) levels with varying service reliability and more optimal network usage than in HSCSD This enables flexible support for connections of different parameters. For example, the video signal could be transmitted with vaπous degrees of eπor protection and delay The mobile stations in the wireless network can be phone units configured to receive and display video signals as well as voice These video display capabilities may support any suitable wireless video transmission standard or propπetary system or may include a web browser, such as Netscape Navigator or Microsoft Internet Explorer, supporting a standardized or propπetary Internet streaming technology. They may also be laptop computers or communicator-like terminals with internet access, in which case the above-mentioned internet transmission methods can be used over the wireless network. Such a device preferably is able to carry out all of the video server control functions of a client discussed below as well as the communication protocols to set-up connection In particular, a remote access system is included so that the mobile phone or other terminal equipment can be remotely accessed by control signals included in the digital service information to, for example, turn the equipment on and off or at least contact the equipment while it is operating is a suspended mode of operation Video Client Fig 2 shows an example of a graphical user interface for the display with some functions of a client device receiving the video signal The display can be a fixed station (e g , a desktop computer) or part of a mobile station The client also has content controls which permit the client to select a clip of video to be displayed In particular, the controls permit the client to control the display of video by selecting functions of PLAY, STOP, REWIND, FORWARD, FAST FORWARD and FAST REWIND in much the same manner as a video cassette recorder In addition, the client can control the video information by reference to a time line or time stamp information associated with the video The controls may also allow the client to designate a time lapse loop Of course, the client is configured to decompress and demultiplex the video signal into its audio, video and time stamp components and display the video and play the audio continually as the video signal is being received Monitoπng Method The monitoπng method according to an example embodiment of the invention is illustrated by the flowchart in Fig 3 In the exemplary embodiment of the invention, a site or premises to be monitored has a camera which generates a video signal of the site (step 301 ) The site has one or more detectors for providing an alarm sιgnal(s) The alarm sιgnal(s) is transfeπed to a central alarm station at the switching station 107 where the alarm signals from a plurality of monitored sites are collected Upon receipt of an alarm (step 302), a connection is set up with the alarm site (step 303) The video picture is transferred as soon as possible to the switching station (step 304) In order to expedite transfer of the picture signal, a short length of video is buffered at the same time it is recorded The video from the alarm site can be displayed on a terminal using the internet or an intranet, ISDN, PSTN or wireless network communication lines directly for a point-to-point connection (step 305) The video signal preferably includes a time stamp indication of the time of an alarm for review simultaneously with the video signal Control signals and commands are transfeπed from the computer to the switching station which instruct the switching station to transmit the appropπate video data just at the alarm time to determine why the alarm occuπed (step 306) This is preferably accomplished by the user clicking on part of the user interface to transmit a command or instruction to the switching station which causes the switching station to in turn respond by transferπng the video data according to the user selection (step 307) For example, if the user pushes the button for rewind, a command is sent to the switching station which represents the user selection of a rewind function and then the video data is virtually rewound In this way, the person can review the video not only at the time that he calls in, but also at the moment of the alarm While the foregoing has descπbed what are considered to be example embodiments of the invention, it is understood that vaπous modifications may be made therein and that the invention may be implemented in vanous forms and embodiments, and that it may be applied in numerous applications, only some of which have been descπbed herein It is intended by the following claims to claim all such modifications and vanations

Claims: CLAIMS 1 A method of monitoπng a site from a remote location by transmitting a video picture generated at the site to the remote location, compnsmg generating a video signal from a video camera located at the site, in response to a request signal, establishing a connection between the site and a display device located at the remote location and transfemng video from the site to the display device at the remote location over said connection, in response to control signals received from the display device, transfemng a portion of the video signal to the display device at the remote location, said portion including video generated at the time of the request signal and pnor to the reguest signal 2 The method recited in claim 1 , wherein the video is transmitted through a wireless network 3 The method recited in claim 1 , wherein the control signals coπespond to the selection of functions on the display device 4 The method recited in claim 3, wherein the functions compnse one or more of the functions of STOP, PLAY, FORWARD and REWIND 5 The method recited in claim 1 , wherein the display on the display device includes a time line coπesponding to said portion of the video signal 6 The method recited in claim 5, wherein the display includes a pointer to select the start time of video to be displayed on the display device 7 The method recited m claim 1 , wherein the request signal is generated upon detection of an event at the site 8 The method recited m claim 1 , wherein the request signal is generated upon an alarm at the site. 9. The method recited in claim 8, wherein the request signal is generated upon an alarm produced by one of a plurality of different detectors at the site. 10 A video monitoπng system monitoπng an alarm site at a remote location, said system compπsing an alarm site having: a video camera, said video camera generating a video signal of the alarm site, at least one detector configured to detect a condition of the alarm site and generate an alarm signal based upon the detected condition; and a server configured to store the video signal, establish a connection with a network in response to an alarm signal remote location and transfer video to the network said connection, a display device at said remote location, said display device configured to display the video signal stored and transfeπed by said server, and a switching element in said network, said switching element configured to provide a connection between said server in the alarm site and said display device at said remote location, wherein control signals are transfeπed from the display device to said server, said control signals causing said server to transfer a portion of the video signal to the display device at the remote location, said portion including video generated at the time of the alarm signal and prior to the alarm signal. 11. The video monitoring system recited in claim 10, wherein the display device is provided within a client terminal, said client terminal having a user interface for controlling the display of video from said server. 12. The video monitoring system recited in claim 1 1, wherein the client terminal generates said control signals in accordance with user selections. 13. The system recited in claim 12, wherein the user selections comprise one or more of the functions of STOP, PLAY, FORWARD and REWIND and the video is transfeπed and displayed according to the selections. 14. The method recited in claim 13, wherein the display on the client terminal includes a time line coπesponding to said portion of the video signal. 15. The method recited in claim 14, wherein the display includes a pointer to select the start time of video to be displayed on the client terminal. 16. A method for use in a video monitoring system in which video from an alarm site is transfeπed to a remote location, said method comprising: in response to an alarm, generating and transferring a video signal of the alarm site to the remote location; and including in said video signal, data indicating the time of said alarm and the coπespondence between frames of the video signal and the time of said alarm. 17. A method as recited in claim 16, wherein a time line is displayed at the remote location utilizing the data included in said video signal.

Inventors: TANSKANEN ERKKI, TANSKANEN, ERKKI
Applicants: NOKIA CORP, NOKIA INC, NOKIA CORPORATION, NOKIA INC.
Application year: 2000
Main classification: H04N7
IPC codes: H04N7