Basic requirements for network transmission, switching and control of security video surveillance systems
- Video surveillance system transmission requirements
(1) Network transmission protocol requirements. The network layer of the networking system must support the IP protocol, and the transport layer must support the TCP and UDP protocols.
(2) Media transfer protocol requirements. When the video/audio stream is transmitted on the IP-based network, it must support the RTP/UDP protocol, and the data encapsulation format of the video/audio stream must meet the following requirements: When the media stream is transmitted on the networked system IP network, it must support the UDP-based RTP protocol , the load of RTP is required to adopt one of the following two formats: video/audio data or video/audio elementary stream data based on PS encapsulation, and the transmission of media streams shall adopt the RTP protocol to provide time stamp information and various data in real-time data transmission For flow synchronization, RTCP protocol should be used to provide reliable guarantee for sequential transmission of data packets, and provide flow control and congestion control.
(3) Information transmission delay time. When information (including video/audio information, control information, and alarm information, etc.) elapsed time) should meet the following requirements.
Between the front-end equipment and the corresponding equipment in the monitoring center directly connected to the signal, the end-to-end information delay time should not be greater than 2s;
Between the front-end equipment and the user terminal equipment, the end-to-end information delay time should not be greater than 4s.
(4) Network transmission bandwidth. The network bandwidth design of the SIP networking system must meet the bandwidth requirements of front-end equipment access to the monitoring center, monitoring center interconnection, and user terminal access to the monitoring center, with a margin. The single-channel network transmission bandwidth of the front-end equipment connected to the monitoring center should not be lower than 512kbps, the single-channel network transmission bandwidth of the front-end equipment connected to the monitoring center in important places should not be lower than 1536kbps, and the single-channel network transmission bandwidth of the network between monitoring centers at all levels The bandwidth should not be lower than 2.5Mbps.
(5) Network transmission quality. The transmission quality of the IP network of the SIP networking system (such as transmission delay, packet loss rate, packet error rate, false packet rate, etc.) should meet the following requirements.
The upper limit of network delay is 400ms;
The upper limit of delay jitter is 50ms;
The upper limit of packet loss rate is 1×10-3;
The upper limit of packet error rate is 1×10-4.
(6) Video frame rate. The video frame rate supported by local recording should not be lower than 25 frames per second. When the image format is CIF, the video frame rate of network transmission should not be lower than 15 frames per second. When the image format is 4CIF, the video frame rate of network transmission should be no less than 15 frames per second. Should not be lower than 10 frames per second.
Second, the basic requirements of video surveillance system exchange
(1) Uniform coding rules. The networked system should uniformly code the front-end equipment, monitoring center equipment, and user terminals, and the code is globally unique. The encoding shall adopt the 20-digit decimal character encoding rule. The local application system can also use the 18-digit decimal number character encoding rule. For the communication between the management platforms of the networked system, and the communication between the management platform and other systems, uniform codes shall be used to identify the equipment and users of the networked system.
(2) SIPURI coding rules. The SIPURI name of the standard equipment of the networking system should adopt the following format:
The username username should be unique in the same SIP monitoring domain, and the domain part of the SIP monitoring domain name contains a complete SIP monitoring domain name.
(3) Media compression encoding/decoding. In the networked system, the video compression encoding/decoding adopts the video encoding and decoding standard H.264/MPEG-4. After the release of the SVAC standard applicable to security monitoring, the SVA standard applicable to security monitoring is given priority; the audio encoding/decoding standard is recommended. G.711/G.723.1/G.729.
(4) Media storage format. In the networked system, media data such as video/audio should be stored in PS format.
(5) Conversion of network transmission protocols. It should support the two-way protocol conversion between the network transmission protocol of non-SIP monitoring domain equipment and the SIP network transmission protocol.
(6) Control protocol conversion. It should support the two-way protocol conversion between the device control protocol of non-SIP monitoring domain devices and the session initiation protocol, session description protocol, control description protocol and media playback control protocol specified in the SIP protocol.
(7) Conversion of media transmission protocols. It should support the two-way protocol conversion between the media transmission protocol and data encapsulation format of non-SIP monitoring domain equipment and the media transmission protocol and data encapsulation format.
(8) Conversion of media data. It shall support converting the media data of non-SIP monitoring domain devices into data conforming to the media encoding format specified in the SIP monitoring domain.
(9) Data exchange with other systems. The networking system provides interfaces with other application systems through the access gateway, and the basic requirements, functional requirements, data specifications, transmission protocols and expansion methods of the interfaces should meet the requirements.
- Basic requirements for video surveillance system control
(1) Device registration. It should support the working mode of registering with the SIP server when the device enters the network system. If the device registration is unsuccessful, it should be delayed for a certain random time and then re-register.
(2) Real-time media on demand. It should support real-time on-demand broadcasting of images according to designated equipment and designated channels, and support simultaneous on-demand broadcasting of the same image resource by multiple users: it is necessary to support real-time audio on-demand or two-way audio pairing between monitoring points and monitoring centers, and between monitoring centers and monitoring centers. Speaking; the session description information adopts the format specified by the SDP protocol.
(3) Historical media playback. It should support remote playback of historical media data at a specified time on a specified device. The playback process should support media playback controls such as normal playback, fast playback, slow playback, screen pause, and random drag and drop.
(4) Equipment control. It should support sending control information to designated devices, such as dome camera/PTZ control, video control, arming/disarming of alarm devices, etc., to realize remote control of various actions of the device.
(5) Notification and distribution of alarm events. It should be able to receive the alarm information sent by the alarm source in real time, and distribute the alarm information to the corresponding user terminal or system equipment in time according to the alarm disposal plan.
(6) Equipment information query. It should support hierarchical query and obtain directory information, status information, etc. of devices registered in the networked system. The device directory information includes device name, device address, device type, device status, etc.; it should support querying basic information of devices, such as device manufacturers , device model, version, supported protocol type and other information.
(7) Submission of equipment status information. It should support the collection and detection of monitoring equipment, alarm equipment, and related server operating conditions in the network by means of active reporting and passive query.
(8) Retrieval of historical media files. It should support the retrieval of historical media files of a specified time period on a specified device.
(9) Online school time. The IP network server equipment in the networked system should support the network unified time checking service of the NTP protocol. The time calibration equipment is divided into clock source and client, and supports the working mode of client/server; the clock source should support TCP/IP, UDP and NTP protocols, and can transmit the input or self-generated time signal in the standard NTP packet format output.
The IP network access device in the networking system should support the unified time calibration of SIP signaling, and the access device should receive the time service carried by the Date field in the message header from the SIP server when registering.