PCT
`
`International Bureau
`WORLD INTELLECTUAL PROPERTY ORGANIZATION
`
`
`
`INTERNATIONAL APPLICATION PUBLISHED UNDER THE PATENT COOPERATION TREATY (PCT)
`
`(51) International Patent Classification 6 :
`WO 97/40624
`
`(11) International Publication Number:
`
`H04N 7/18, 9/47
`
`
`
`(43) International Publication Date:
`30 October 1997 (30.10.97)
`
`(21) International Application Number:
`PCT/US97/06844
`(81) Designated Statesc AL, AM, AT, AU. AZ. BA, BB. BG. BR.
`BY, CA, CH, CN, CU, cz, DE, DK. EE, ES, FI, GB, GE.
`
` (22) International Filing Date: 17 April 1997 (17.04.97)
`
`HU, IL, 15, JP, KE, KG, KP, KR, KZ, LC, LK, LR, LS,
`
`
`LT, LU, Lv, MD, MG, MK, MN. MW, Mx, NO, NZ, PL,
`
`
`PT, RO, RU, SD, SE, 56, SI, SK, TJ, TM, TR, "IT, UA.
`(30) Priority Data:
`
`
`UG, UZ, VN, ARIPO patent (611, KB, Ls, Mw, SD. 52,
`22 April 1996 (22.04.96)
`US
`08/635,692
`
`U6), Eurasian patent (AM, AZ, BY, K , KZ, MD, RU. TI,
`
`TM), European patent (AT, BE, CH, DE, DK, ES, Fl, FR.
`
`
`GB, GR, IE. IT, LU, MC, NL, PT, SE), OAP patent (BF,
`(71) Applicant:
`SENSORMATIC ELECTRONICS CORPORA-
`
`
`BJ, CF. CG, CI, CM, GA, GN, ML, MR, NE, SN. TD. TG).
`
`TION [US/US]; 951 Yamato Road, Boca Raton, FL 33431»
`
`0700 (US).
`
`Published
`
`
`
`
`(72) Inventor: ELY, Reucl, Andrew; 560 NW. 66th Avenue,
`With international search report.
`
`
`
`Plantation, FL 33317 (US).
`Before the expiration of the time limit for amending the
`
`claims and to be republished in the event of the receipt of
`amendments.
`
`
`(74) Agent: TORRENTE, John, 1.; Robin. Blacker, Daley &
`Driscoll, 330 Madison Avenue, New York, NY 10017 (US).
`
`
`
`
`
`
`(54) Title: DISTRIBUTED VIDEO DATA STORAGE IN VIDEO SURVEILLANCE SYSTEM
`
`
`
`
`ANALOG
`
`VIDEO
`
`
`
`VCR
`
`
`CONTROL
`
`
`COMMAND, STATUS, VIDEO DATA
`
`CENT RAL
`
`STATION
`
`
` (57) Abstract
` -
`A video surveillance system includes a central control Station (102) and a plurality of video cameras each mounted inside a dome
`housing unit (I I4). A video data buffer memory. storing compressed video data generated by the camera. is mounted with each camera in
`
`
`
`the respective dome unit. Data buffered at the dome units may be selectively protected from over—writing in response to alarm signals and
`then retrieved for display or tape-recording by the central control station. Both live and buffered video signals are transmitted in compressed
`
`
`
`form over the data network (112) that is also used for'command, alaxm and status messaging.
`
`
`
`
`__ 1 __
`
`MOBOTIX 1005
`
`-- 1 --
`
`MOBOTIX 1005
`
`

`

`FOR THE PURPOSES OF INFORMATION ONLY
`
`Zimbabwe
`
`Codes used to identify States party to the PCT on the front pages of pamphlets publishing international applications under the PCT.
`SI
`Slovenia
`ls
`Lesotho
`ES
`Albania
`SK
`S iovakia
`LT
`Lithuania
`F1
`Armenia
`LU
`SN
`FR
`Austria
`Luxembourg
`Senegal
`82
`Swaziland
`LV
`Latvia
`GA
`Auslmliu
`TD
`Chad
`Monaco
`GB
`MC
`Azerbaijan
`T6
`MD
`GE
`Togo
`Republic of Moldova
`Bosnia and Herzegovina
`'1‘]
`MG
`GH
`Barbados
`Madagascar
`Tajflzisnn
`Turkmenistan
`TM
`MK
`GN
`The former Yugoslav
`Belgium
`TR
`GR
`Burkina Faso
`Turkey
`Republic of Macedonia
`TT
`Mali
`'HU
`Trinidad and Tobago
`Bulgaria
`UA
`Ukraine
`[E
`Benin
`Mongolia
`UG
`[L
`Mauritania
`Brazil
`Uganda
`US
`United States of America
`IS
`Malawi
`Belarus
`UZ
`Uzbekistan
`IT
`Mex iuo
`Canada
`VN
`Vie: Nam
`JP
`Niger
`Central African Republic
`YU
`Nethedands
`KE
`Yugoslavia
`Congo
`2“]
`Switzerland
`Norway
`New Zealand
`Cate d'lvoire
`Poland
`Cameroon
`China
`Portugal
`Romania
`Cuba
`Russian chamion
`Czech Republic
`Sudan
`Germany
`Sweden
`Denmark
`Estonia
`Singapore
`
`Spain
`Finland
`France
`Gabon
`Uniied Kingdom
`Georgia
`Ghana
`Guinea
`Greece
`Hunzaw
`lreland
`Israel
`Iceland
`Italy
`Jae-n
`Kenya
`Kyrgyzstan
`Dcmocmic People's
`Republic of Korea
`Republic of Korea
`Kaulutan
`Saint Lucia
`Liechtenstein
`Sri Lanka
`Liberia
`
`ML
`MN
`MR
`MW
`MX
`NE
`NL
`NO
`NZ
`PL
`PT
`RO
`RU
`SD
`SE
`SG
`
`-- 2 --
`
`

`

`WO 97/40624
`
`PCT/US97/06844
`
`DISTRIBUTED VIDEO DATA STORAGE IN
`
`VIDEO SURVEILLANCE SYSTEM
`
`FIELD OF THE INVENTION
`
`This
`
`invention is
`
`related to video
`
`surveillance
`
`systems, and more particularly to surveillance systems of
`
`the type which include sensors for advising the system of
`alarm conditions.
`
`BACKGROUND OF THE INVENTION
`
`A
`
`conventional
`
`closed—circuit
`
`video
`
`surveillance
`
`system,
`
`indicated generally by refierence numeral 10,
`
`is
`
`illustrated in block diagram form in Fig. 1.
`
`The surveillance system 10
`
`includes a host computer 12,
`
`which controls the operation of the system, a video switch
`
`14 which selectively interconnects
`
`input video signals
`
`(represented by dashed lines 16) with outputs of the switch
`
`(represented by dashed lines 18). Also included in the
`
`system 10 are video cameras
`
`20, monitors 22,
`
`control
`
`consoles 24, and sensor devices 26. A local area network 28
`
`is provided for interchange of command, status and alarm
`
`data between the system host 12 and the cameras 20, control
`consoles 24 and sensors 26.
`
`A user interface 30 is also provided to permit a system
`operator to control operations of the system. The interface
`
`30 may incorporate a monitor and a control console which are
`
`not
`
`shown separately from the user
`
`interface 30. Also
`
`included in the system 10 are one or more video cassette
`
`recorders 32 which are available to record video signals
`that are generated by the video cameras 20 and selectively
`routed to the VCRs 32 by way of the video switch 14. Video
`
`10
`
`15
`
`20
`
`25
`
`30
`
`signals previously recorded by the VCRs 32 can be played
`-back by the VCRs 32 and selectively routed through the
`switch 14 for viewing on one or more of the monitors 22. As
`
`35
`
`is well known to those who are skilled in the art, system
`host
`12 also controls the video switch 14
`so that,
`in
`
`response to control signals entered via the control consoles
`
`-1-
`
`-- 3 --
`
`

`

`WO 97/40624
`
`PCT/US97/06844
`
`24, video signals generated by a selected one of the video
`
`cameras 20 is routed for viewing at a selected one of the
`
`monitors 22. Sensors 26 generate alarm signals in response
`
`to anomalous events such as unauthorized opening of doors,
`
`windows or display cases.
`
`The system host 12 operates to
`
`inform the human operator of
`
`the alarm conditions,
`
`and
`
`predetermined camera movements and routing of corresponding
`
`video
`
`signals
`
`to
`
`pre—selected monitors
`
`22 may
`
`be
`
`10
`
`to alarm signals.
`automatically, actuated in response
`Movement of
`the cameras can also be controlled through
`
`commands
`
`issued by the system host,
`
`in response to pre‘
`
`programmed surveillance routines, or in response to operator
`
`input through the control consoles 24 or the user interface
`30.
`
`15
`
`2O
`
`25
`
`30
`
`35
`
`It is generally a desired goal
`
`in video surveillance
`
`systems
`
`that video signals representative of conditions
`
`before, during and after the onset of an alarm event be
`
`recorded for current and future reference, subsequent legal
`
`proceedings, and so forth, and it is for this purpose that
`
`the VCRs 32 are provided.
`
`However, surveillance systems
`
`frequently include a large number of video cameras (e.g.,
`dozens or hundreds of cameras),
`and the cost of video
`
`cassette recorders is too high to permit recording of the
`
`signals generated by more than a few of the cameras at any
`
`given time.
`
`In
`
`conventional
`
`systems,
`
`video signals
`
`indicative of conditions prior to an alarm event cannot be
`
`recorded, unless the output of
`
`a video camera has been
`
`routed for recording by a VCR prior to the time an alarm
`event occurs.
`
`To maximize the recording capacity of the VCRs, it is
`
`known to provide space-division-multiplexed (e.g., quad
`
`umltiplexed) signals for recording on VCRs 32, and it is
`
`also known to operate the VCRs in a time lapse mode, with a
`reduced frame rate and switching among a number of cameras.
`
`When
`
`an
`
`alarm occurs,
`
`the
`
`time
`
`lapse mode
`
`can
`
`be
`
`automatically stopped in favor of a standard frame rate
`
`recording operation for the critical camera or cameras.
`
`In
`
`addition, critical cameras can be connected at all times for
`
`_2_
`
`-- 4 --
`
`

`

`WO 97/40624
`
`PCT/US97/06844
`
`recording by
`
`a dedicated VCR.
`
`There
`
`are,
`
`however,
`
`disadvantages with all of these techniques. As noted above,
`
`it is quite expensive to provide a large number of VCRs, and
`
`if
`
`space—division—multiplexing is employed,
`
`the spatial
`
`resolution of the image signal is reduced, which may impair
`recognition of critical elements of the recorded images. On
`the other hand,
`time lapse recording suffers from reduced
`temporal resolution,
`so that again critical events may be
`missed. And, as noted before, if a camera having a view of
`an alarm event
`is not being recorded prior to the alarm
`
`10
`
`the critical video information may simply fail to be
`event,
`captured.
`
`An "intrusion tmonitoring'
`
`system" disclosed in U.S.
`
`15
`
`and
`5,109,278
`Patent Nos.
`Commonwealth Edison)
`attempts
`
`to
`(assigned
`5,111,291
`to address some of
`these
`
`20
`
`25
`
`30
`
`problems by providing an analog—to—digital converter and
`
`frame buffers at
`
`the output of
`
`a video multiplexer.
`
`Although the system disclosed in the Com Ed patents provides
`some capability for capturing and storing signals indicative
`of conditions at or before the time that an alarm event
`
`occurs,
`
`the system does not seem to be adapted to operate
`
`with a large number of cameras, and the temporal resolution
`
`is poor, especially when the system includes more than a
`minimal number of cameras.
`
`OBJECTS AND SUMMARY OF THE INVENTION
`
`It is accordingly an.object of the invention to provide
`
`a video surveillance system having an improved capability
`for storage of video signals-
`
`the invention to provide a
`is another object of
`It
`video surveillance system in which buffer
`storage
`is
`provided for video signals generated by all of the cameras
`
`in the system, and it is a further object
`
`to provide such
`
`35
`
`buffer storage for all cameras in the system even when the
`number of cameras is large.
`
`It
`
`is still
`
`a further object of
`
`the invention to
`
`provide a video surveillance system in. which a
`
`human
`
`operator can conveniently control buffering and permanent
`
`-3-
`
`-- 5 --
`
`

`

`WO 97/40624
`
`PCTlUS97/06844
`
`recording of video signals generated by all of
`
`the video
`
`cameras in the system.
`
`It is yet another object of the invention to provide a
`
`video surveillance systenlin which storage for Video signals
`
`generated by each camera is carried out at low cost.
`It is yet a further object of the invention to provide
`a video surveillance system which requires less cabling than
`
`conventional systems.
`
`10
`
`15
`
`20
`
`25
`
`According to an aspect of
`
`the invention,
`
`there is
`
`provided a video surveillance system,
`
`including a central
`
`station, a plurality of video cameras located remotely from
`
`the central station for generating respective video signals,
`
`a plurality of storage devices, each located remotely from
`the central station and associated with a respective one of
`
`the
`
`video
`
`cameras
`
`for
`
`storing digital
`
`video
`
`data
`
`representative of
`
`the video
`
`signal generated by
`
`the
`
`respective video camera,
`
`and connection circuitry for
`
`forming a signal path between the central station and each
`
`of the storage devices:
`
`Further
`
`in accordance with
`
`this
`
`aspect
`
`of
`
`the
`
`invention,
`
`the connection circuitry may include a plurality
`
`of
`
`control Adevices
`
`each operatively connected
`
`to
`
`a
`
`respective one of the storage devices for controlling the
`
`respective storage device to operate as a ring buffer in
`
`which digital video data representative of video signals
`
`currently' generated by the respective video camera
`
`is
`
`written over oldest digital video data stored.
`
`in the
`
`respective storage device. The surveillance systenlprovided
`
`3O
`
`further
`the invention may'
`according to this aspect of
`include a sensor device for generating an alarm signal
`
`indicative of
`
`an
`
`alarm condition,
`
`and circuitry for
`
`transmitting the alarm signal from the sensor device to the
`
`central
`
`station.
`
`The central
`
`station may
`
`respond to
`
`receiving the alarm signal by transmitting a storage signal
`to at least one of the control devices, such control device
`
`35
`
`or devices responding to the storage signal by inhibiting
`
`over—writing of
`
`the oldest digital video data in the
`
`respective storage device or devices controlled by such
`
`-4-
`
`-- 6 --
`
`

`

`WO 97/40624
`
`PCT/US97/06844
`
`control device or devices. Alternatively; the sensor device
`
`may be coupled to the connection circuitry for transmitting
`
`the alarm signal directly to the control device or devices,
`
`such device or devices responding to the alarm signal by
`
`inhibiting over—writing of the oldest digital video data in
`the respective storage device or devices controlled by such
`control device or devices.
`
`10
`
`15
`
`20
`
`Still further in accordance with this aspect of
`
`the
`
`invention,
`
`the central station may selectively transmit a
`
`retrieve signal to a selected one of the control devices,
`
`which.responds to the retrieve signal by transmitting to the
`
`central station digital video data read out from the storage
`device controlled by the selected control deviCe.
`
`The system provided in accordance with this aspect of
`
`the
`
`invention may
`
`further
`
`include
`
`a display device
`
`associated with the central station for displaying images
`
`corresponding to the digital video data read out
`
`from the
`
`storage device and transmitted to the central station, as
`
`well as a video tape recorder controlled by the central
`
`station for recording signals corresponding to the digital
`
`video data read out from the storage device and transmitted
`to the central station.
`
`The connection circuitry may include a common data
`
`25
`
`are
`signals
`command
`by which
`channel
`transmission
`transmitted from the central station to the video cameras
`
`and digital video data read.out from the storage devices is
`
`transmitted to the central station. The digital video data
`
`stored in the storage devices and transmitted by the data
`
`3O
`
`data.
`video
`compressed
`be
`channel may
`transmission
`Preferably each of
`the storage devices is a solid state
`
`memory and each is disposed.in a respective housing together
`with the respective video camera.
`
`According to another aspect of the invention, there is
`provided a surveillance Video camera unit,
`including a
`housing which includes a light transmissive portion, a video
`
`35
`
`camera disposed within the housing for forming an image from
`
`light which passes through.the light transmissive portion of
`
`the housing and for converting the image
`
`into a video
`
`-5-
`
`-- 7 --
`
`

`

`WO 97/40624
`
`PCT[US97/06844
`
`signal, and a storage device, disposed within the housing,
`
`for storing digital data representative of the video signal.
`
`S
`
`10
`
`Further in accordance with the latter aspect of
`
`the
`
`invention,
`
`the video signal generated by the video camera
`
`may he an analog video signal, in which case the camera unit
`
`includes conversion circuitry disposed within the housing
`
`for converting the analog video signal into a digital video
`signal, and processing circuitry disposed within the housing
`for applying a data compression algorithm to the digital
`
`Video signal to form compressed video data,
`
`the compressed
`
`video data being stored in the storage device.
`
`The
`
`conversion circuitry and the processing circuitry may be
`integrated with the video camera so that the video camera
`
`~15
`
`outputs the compressed video data to the storage device.
`
`20
`
`25
`
`30
`
`35
`
`Still further in accordance with this aspect of the
`
`invention,
`
`the camera unit may include a control circuit
`
`disposed within the housing for controlling the storage
`
`device to operate as a ring buffer in which digital data
`
`representative of a video signal currently formed by the
`
`video camera is written over oldest digital data stored in
`
`the storage device.
`
`In response to receiving an event
`
`signal,
`
`the control circuit
`
`inhibits over—writing of
`
`the
`
`oldest digital data.
`
`'
`
`There may further be provided in the camera unit
`
`a
`
`plurality of motors disposed in the housing for changing
`
`pan, tilt and zoom conditions of the video camera, and the
`
`control circuit generates control signals for controlling
`
`the plurality of motors,
`
`the camera unit further including
`
`circuitry for transmitting the control signals from the
`
`control circuit to the plurality of motors. Preferably the
`
`storage device is a solid state memory.
`
`According to still another aspect of
`
`the invention,
`
`there is provided a method of
`
`storing video signals,
`
`including the steps of generating digital video signals
`
`using a plurality of video cameras, storing the digital
`
`video signals generated by each. camera.
`
`in a respective
`
`storage device provided adjacent
`
`to
`
`the
`
`camera,
`
`and
`
`_6_
`
`-- 8 --
`
`

`

`WO 97140624
`
`v
`
`PCT/US97/06844
`
`selectively transmitting to a central station the digital
`video signals stored in each storage device.
`Further in
`
`the method may
`accordance with this aspect of the invention,
`include operating the storage devices as ring buffers in
`
`which currently generated digital video signals are written
`over oldest digital video signals stored in the storage
`devices,
`and inhibiting the over—writing of
`the oldest
`
`digital video signals in response to receipt of an event
`
`tape—
`The method may also include the steps of
`signal.
`recording signals corresponding to the digital video signals
`transmitted ’to the central station, and displaying images
`corresponding to the digital video signals transmitted to
`
`the central station.
`
`‘
`
`According to yet another aspect of the invention, there
`is provided a video
`surveillance
`system including a
`plurality of video cameras for generating the video signals,
`digital storage Circuitry for storing the video signals in
`the form of digital video data, control circuitry for
`generating camera control
`commands,
`data
`transmission
`
`circuitry for forming a data communication channel by which
`the camera control commands are transmitted from the control
`
`circuitry to the plurality of video cameras, and circuitry
`for retrieving the stored digital data from the digital
`storage circuitry and for transmitting the retrieved digital
`video data
`to the
`control
`circuitry via
`the
`data
`
`communication channel
`circuitry.
`
`formed by the data transmission
`
`The video signals generated by the video cameras may be
`analog video signals,
`in which case the digital storage
`circuitry includes circuitry for converting the analog video
`signals
`into digital , video signals
`and circuitry for
`compressing the digital video signals to form compressed
`digital video data.
`Alternatively,
`the video signals
`-generated by the video cameras may be
`in the form of
`compressed digital video data.
`
`The digital storage circuitry may include a plurality
`of digital storage devices,
`each located adjacent
`to a
`respective one of
`the video cameras,
`and the retrieving
`-7-
`
`10
`
`15
`
`20
`
`25
`
`30
`
`35
`
`-- 9 --
`
`

`

`WO 97/40624
`
`PCT/US97/06844
`
`circuitry may include a plurality of control devices, each
`
`associated with the respective one of the digital storage
`
`devices. Preferably, each of the storage devices is a solid
`
`state memory.
`
`By providing a video surveillance system that includes
`
`camera units having digital storage for signals generated in
`
`the respective camera unit, video signals corresponding to
`conditions before, during and after an alarm event can be
`
`conveniently and reliably stored, and the locally stored
`
`video can be read. out
`
`and transmitted to an, operator—
`
`attended station at
`
`a convenient
`
`time for' viewing and
`
`The data communication
`permanent recording on video tape.
`network used for transmission of command and status data
`
`between.the system central station and the video cameras may
`
`be provided with sufficient capacity to handle transmission
`
`of compressed video data buffered or currently generated at
`
`the video camera units,
`
`in which case separate video signal
`
`transmission cabling can be dispensed with.
`
`The
`
`foregoing
`
`and
`
`other objects,
`
`features
`
`and
`
`advantages of the invention will be further understood from
`
`the following detailed description of preferred embodiments
`
`the invention. and from the drawings,
`and. practices of
`wherein_like reference numerals identify like components and
`
`parts throughout.
`
`DESCRIPTION OF THE DRAWINGS
`
`Fig.
`
`l
`
`is a block diagram of
`
`a conventional video
`
`surveillance system.
`
`Fig.
`
`2
`
`is a block diagram of a video surveillance
`
`system provided in accordance with the present
`
`invention.
`
`Fig.
`
`3
`
`is a schematic illustration of a video camera
`
`unit used in the system of Fig. 2.
`
`Fig.
`
`4 is a flow chart of processes carried out
`
`in a
`
`control circuit that is part of the camera unit of Fig. 3.
`
`Figs. 5A and SB together form a flow chart of processes
`
`carried out in a host computer that is part of the system of
`
`Fig. 2.
`
`10
`
`15
`
`20
`
`25
`
`30
`
`3S
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`

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`WO 97/40624
`
`,
`
`PCT/U897106844
`
`2E§QBlEElQH.QE_EBEEEEEEQ_EMEQQLMEEI§_AEQ_EEA§EIQ§§
`
`An embodiment of the invention will now be described,
`initially with reference to Fig. 2. Reference numeral 100
`
`generally indicates a video surveillance system provided in
`
`5
`
`The system 100 includes a
`accordance with the invention.
`central
`station. 102 at which a host
`computer
`104
`is
`provided. Associated with the host computer 104 are a video
`
`data encoding/decoding device 106 and hardware and software
`
`required to provide a user interface, represented by block
`108.
`The host
`computer' 104 controls a video cassette
`
`10
`
`recorder 110.
`
`A local area network (LAN) 112 is connected
`
`to the host computer 104. Data communicated between the
`
`host 104 and other components of the system 100 is carried
`
`over the LAN 112. Other system components connected to the
`
`15 host computer 104 via the LAN 112 include camera units 114,
`monitors
`116
`(each connected to the LAN’ 112
`through, a
`respective video data decoding device 118)
`and sensor
`
`devices 120.
`conventional
`
`The sensor devices 120 are preferably of
`types that detect,
`for example, unauthorized
`
`20
`
`opening of doors, windows and display cases and the like and
`
`generate alarm signals indicative of these occurrences. The
`sensors 120 may also include conventional motion and/or heat
`sensing devices. The monitors 116 and the VCR 110 are also
`preferably conventional commercially—available items.
`It
`
`25
`
`should.be understood that although only one VCR 110 is shown
`
`in Fig. 2,
`system 100.
`
`two or more VCRs may be provided as part of the
`
`Although
`
`the user
`
`interface
`
`108
`
`is
`
`represented
`
`separately from the monitors 116, it should be understood
`
`30
`
`that the user interface preferably includes one or more of
`
`input/output devices
`as other
`as well
`such monitors,
`commonly provided as peripherals to personal computers.
`In
`addition,
`the user interface 108 may include one or more
`camera control devices such as the "TOUCHTRACKER" control
`
`35
`
`this application.
`consoles marketed by the assignee of
`Additional camera control consoles, although not shown, may
`be provided in the system at or remote from the central
`
`__11__
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`

`

`W0-97l40624
`
`PCTMSW/06844
`
`station 102, and connected to the host 1Q4 through the LAN
`112.
`
`The
`
`camera units
`
`114 are preferably' of
`
`a design
`
`provided in accordance with an aspect of the invention, as
`illustrated in Fig. 3.
`Each camera unit may be mounted at a ceiling 122 or at
`
`another appropriate location,
`
`and includes a housing 124
`
`constituted, at least in part, by a base portion 126 and a
`
`dome portion 128.
`
`In accordance with conventional practice,
`
`the dome portion 128
`
`is formed of
`
`a light—transmissive
`
`material
`
`that allows light
`
`to enter the interior of
`
`the
`
`housing 124, although the material of which dome 128 is made
`
`so that
`"one way“
`be
`screened from view.
`
`the interior of
`
`the unit 114 is
`
`Mounted within the housing 124 of the camera unit 114,
`
`and preferably mounted on the base portion 126, are a video
`
`camera 130, motors and other structure 132 for changing pan,
`
`tilt,
`
`zoom and/or other conditions of
`
`the camera 130,
`
`a
`
`control circuit 134, and a memory board.136. The camera 130
`
`may be of conventional design,
`
`and includes an optical
`
`system 138 that receives and forms into an optical
`
`image
`
`into the
`128
`through the dome
`140 which. passes
`light
`interior of the camera unit 114.
`The image formed by the
`
`10
`
`15
`
`2O
`
`optical system 138 is converted into an electrical signal at
`CCD
`142
`and
`the
`resulting signal
`is
`subjected
`to
`
`25
`
`conventional
`
`analog signal processing at video signal
`
`A suitable camera for use in the
`processing circuit 144.
`camera unit 114 is commercially available from the assignee
`
`30
`
`35
`
`of
`
`the
`
`present
`
`application,
`
`Sensormatic Electronics
`
`Corporation, as part number 2003-0037—00. Other suitable
`cameras are also commercially available.
`
`The camera Haunting structure, pan,
`
`tilt,
`
`and zoom
`
`motors, and so forth indicated by reference numeral 132 are
`
`also preferably of conventional design, such as are provided
`
`on commercially available camera dome units.
`
`The control
`
`circuit 134 may be a conventional microcontroller, such as
`
`is currently used in camera dome units to receive command
`
`signals from, and transmit status data to, a system central
`
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`

`

`WO 97/40624
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`-
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`PCT/US97/06844
`
`control station, and also for controlling the camera motors
`
`and detecting the status (such as position) of the camera
`
`motors,
`
`in a conventional manner.
`
`However,
`
`the control
`
`circuit 134 shown in.Fig.
`
`3 is also programmed, according to
`
`to carry out memory
`invention,
`the present
`practices of
`control, as well as data storage and retrieval functions
`
`that will be described below.
`
`10
`
`15
`
`The memory board 136 is provided in accordance with the
`
`invention to receive an analog video signal output from the
`
`camera 130 and to digitize, compress and store the video
`
`signal. Components of the memory board 136 include a video
`
`digitizer circuit 146, a video data coding/decoding circuit
`148 and a memory device 150. The video digitizer 146 may be
`suitably realized by the "WAVEWATCHER TV II" video digitizer
`card.
`available
`from AITech
`International,
`Fremont,
`California.
`A suitable video codec is the model VCI-lO,
`available from VistaCom, OY, Tietajantie 14, 02130, Espoo,
`Finland.
`The model VCI—lO compresses video data
`in
`
`20
`
`accordance with the H.261 standard, and also provides the
`function of
`reconstituting video data
`that
`has
`been
`
`The memory
`compressed in accordance with that standard.
`device 150 may be constituted by one or more of RAM, EEPROM,
`flash memory, and so forth.
`As will be seen,
`the memory
`device 150
`functions as
`a buffer'
`for
`the video signal
`generated by the camera 130,
`and is controlled. by the
`control circuit 134.
`
`It is expected that, within a short
`
`time,
`
`there will
`
`become
`
`commercially'
`
`available
`
`video
`
`cameras which
`
`incorporate the video signal digitizing and, compression
`functions carried out at blocks 146 and 148 in Fig. 3.
`For
`example, commercial
`introduction of a video camera which
`
`outputs compressed digital video data in accordance with the
`
`above—mentioned, H.261 standard,
`
`is anticipated.
`
`Such. a
`
`'camera could be used in place of
`
`the camera 130 shown in
`
`Fig. 3, and the separately-provided video digitizer 146 and
`video codec
`148 could be omitted, with the compressed
`digital video signal output
`from the camera being stored
`
`25
`
`30
`
`35
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`WO 97/40624
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`PCP/US97I06844
`
`directly in the memory device 150 under the control of the
`control circuit 134.
`
`Operation of the camera unit 114 will now be described,
`
`4, which illustrates processes
`with reference to Fig.
`carried out by the control circuit 134 under the control of
`
`5
`
`a stored program.
`
`(It will be understood that the program
`
`memory is not
`134.)
`
`shown separately from the control circuit
`
`10
`
`One ongoing process carried out under normal conditions
`by the control circuit 134 is transmission to the central
`station (via. LAN 112)
`of
`compressed video data which
`
`represents video signals currently being generated by the
`
`camera
`
`130.
`
`This process,
`
`represented by block 152,
`
`includes receiving the live compressed video data from the
`
`15 video codec 148 and coupling the data onto the LAN 112,
`
`either according to predetermined time slots, or in response
`
`to commands from the central station, or according to some
`
`other protocol.
`
`In parallel with the process represented by
`
`block 152,
`
`the live compressed video data formed by the
`
`20 video codec
`
`148
`
`is 'also stored in the memory
`
`150.
`
`Preferably the memory addressing and writing of data into
`
`the memory is controlled by the control circuit 134 so that
`the memory 156 serves as a ring buffer,
`in which currently
`
`generated compressed video data is written over the oldest
`
`25
`
`compressed video data that had previously been stored in the
`
`memory 150.
`
`However, over-writing of the oldest data is
`
`subject
`
`to inhibition in response to alarm commands.
`
`On
`
`such occasions,
`
`the live compressed video data is written
`
`into a portion of the memory device 150 which does not hold
`
`30 video data that is to be preserved.
`
`In a third ongoing process, represented by block 156,
`
`the control circuit
`
`134 handles camera control
`
`commands
`
`received via the LAN 112.
`
`The handling of camera control
`
`commands is in accordance with conventional practice, and a
`
`35
`
`further discussion thereof consequently will be omitted.
`
`Concurrently with the ongoing processes of blocks 152,
`
`154 and 156,
`
`the control circuit 134 is conditioned to
`
`receive occasional alarm commands, as indicated by decision
`
`-12-
`
`__ 14--
`
`-- 14 --
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`

`

`WO 97/40624
`
`.
`
`PCT/US97/06844
`
`block 158. When an alarm command is received, a process
`(indicated.by block 160) is carried out in which the control
`
`circuit 134 protects from over—writing compressed digital
`video data previously stored in the memory
`150,
`and
`
`a
`at
`beginning
`interval
`time
`a
`to
`corresponding
`predetermined time prior to receipt of the alarm command,
`and continuing for a predetermined time after receipt of the
`alarm command.
`
`10
`
`(as
`is also conditioned
`134
`control circuit
`The
`indicated.by decision block 162) to receive commands calling
`for reading—out and transmission to the central station of
`
`previously—stored compressed video data. The stored data to
`
`be retrieved may be data that was previously protected from
`
`15
`
`over—writing in response to an alarm command, or may be
`other data that has previously been stored in the buffer
`
`20
`
`25
`
`3O
`
`35
`
`memory 150. When a retrieve command is received, a process
`for reading out
`the stored data from the buffer memory and
`'transmitting the read—out data via the LAN 112 is carried
`
`out, as represented by block 164.
`
`The transmission of the
`
`compressed video data that was read out from the memory 150
`may be in place of, or virtually in parallel with, continued
`transmission of "live" compressed video data. Preferably,
`as suggested by Fig. 4,
`transmission of stored compressed
`video data in response to corresponding retrieval commands
`
`does not interrupt ongoing storage of "live" video data.
`
`As indicated by decision block 166,
`
`the control circuit
`
`134 is also conditioned to receive "clear" commands,
`
`in
`
`response to which the control circuit removes a previously
`protected block of
`stored video data from protection,
`thereby permitting "live" video data to be written over the
`now—unprotected stored video data.
`
`Overall operation of the system 100 (Fig. 2) will now
`be described, with reference to Figs.
`5A and 5B, which
`illustrate processes carried out by the host computer 104.
`As
`indicated at block 170
`in Fig.
`5A, one ongoing
`process
`performed
`by
`the host
`computer
`104
`entails
`controlling
`camera movements,
`etc.,
`in
`response
`to
`instructions input by users of the systent The instructions
`
`-13..
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`

`WO 97/40624
`
`-
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`PCT[USN/06844
`
`may be received either through the user interface 108, or
`
`via separate camera control consoles, which are not shown.
`
`The receipt of user instructions, processing of same by the
`
`host
`
`computer
`
`104,
`
`generation of
`
`command
`
`data
`
`and
`
`transmission of
`
`the command data via LAN 112, and camera
`
`in response to the
`etc.)
`zoom,
`(pan, Vtilt,
`movements
`commands are all preferably carried out
`in a conventional
`
`manner, and therefore will not be described further.
`
`The
`
`10
`
`15
`
`20
`
`25
`
`process 170 can also be considered as encompassing receipt
`
`and processing of status data transmitted on the LAN 112 by
`the camera units
`114,
`in accordance with conventional
`
`practice. Although the discussion up to this point has
`
`suggested that all user camera control
`
`instructions are
`
`processed in the host 104 and then relayed to the cameras
`
`114 via the LAN 112,
`
`it is also contemplated that camera
`
`control consoles (not shown) connected to the LAN 112 may
`
`generate commands
`
`that are addressed directly to,
`
`and
`
`processed only by, camera units 114.
`
`Another ongoing function‘ carried. out by the host
`
`and
`5A,
`is indicated at block 172 in Fig.
`computer 104
`relates to handling user instructions for displaying "live"
`
`video signals generated by the cameras 114.
`
`In essence,
`