Web-based intelligent video intercom control systems design

Summary: in order to adapt to the development of intelligent building, has designed a set of intelligent video intercom monitoring system.

System uses computer network technology, video intercom, video surveillance and access control card section of data to the Terminal, and the various components of the consolidated control, while also significantly reducing construction costs for installation, wiring. Through a system of hardware and software mode, run the satisfactory results.

I. introduction

With the improvement of living standards and the rise of intelligent building, residence and more attention to security issues.

In order to meet the security requirements of a modern building, the people developed a number of safety monitoring system, such as access control systems, video surveillance, one-card system and so on. Technology mainly audio processing, video processing technology and control information processing technology, and the third part of the processing and delivery are all separate, this increases the total cost of the product, in particular the construction and installation, wiring costs, but also to the product technical upgrade of great difficulty. In this, we use a network technology, and fusion of computer technology, automatic control technology and electronic technology, the three parts into a whole, using the Internet to pass information to the user terminal and management Terminal, thereby achieving the unity of the subsystem or control significantly reduces the construction and installation, wiring costs.

II. system composition

Smart video intercom monitoring system mainly includes Talkback section, card access control and video surveillance consists of three parts.

Talkback section mainly for visitors, users, Terminal and manage Terminal provides a recognition and dialogue channel. Card access control section is for the convenience of the users, especially when users out who has multiple security system, a cartoon system will bring very large for the user's convenience. Video surveillance section is mainly used for monitoring user around, including two parts, one is a video intercom, video surveillance, another part is user around the public such as corridors, elevators and other necessary monitoring sites, etc.

Three parts over a computer network as a whole, constitute a complete product.

The entire computer network consists of two totally independent network, a set is a set of Ethernet, is 485 half-duplex communication network, its structure as shown in Figure 1. 100Mbps Ethernet mainly used to transport real-time video streaming data and control information and other information, 485 communication network is used for connecting the door Terminal and user terminal.

　　

　　

Third, computer network technology

System uses two separate network system, the first set is based on 485 half-duplex network system, the second set is based on Ethernet LAN.

Based on 485 half-duplex network system to connect the gate terminal, tiered, and user terminals, mainly on account of the cost. Because of this three part-exchange of information is relatively small, the data exchange speed is not very high and realization of relatively simple, it uses this network system.

Communication using point-to-multipoint mode.

Communication mode as shown in Figure 2.

　　

　　

From the door Terminal sends a frame information for tiered, hierarchical is received, the call hierarchy for information distribution to this layer all user terminal, and wait for the confirmation of the user terminal.

Called by the user terminal to receive information, a confirmation message to be sent immediately to the tiered, hierarchical is received later, to the gate terminal sends a confirmation message. The gate terminal receives confirmation of layered, open camera and audio microphone, you can engage in dialogue.

The system uses a tiered to forward a message frame was designed to prevent when hook in 485 users too much when overload causing panic.

Information frame structures composed by 5 bytes, the first byte of the recording layer information, the second byte records user terminal, information, third and fourth bytes to checksum, the fifth byte control flag in front of this byte 3 bit set, after a 5-bit-flags of the Synchronize flag 1, 2, recognized the synchronization flag signs 1, 2, and error confirmed flag. The gate terminal in sending at the same time reset bit SYS1 = 1, layered with forwarding, reset bit SYS2 = 1. The same user confirmation reset bit ACK = 1, layered with confirmation set bits ACK2 = 1. When an error occurs a system reset bit ERR = 1 for appropriate processing.

The second set of network system is based on Ethernet LAN, main monitoring system of communication function, as shown in Figure 1.

The system uses RTP on video data (using H.26 1 coding) package, use 5 recommendations to package H.22 and transfer the information flow (video streaming and other control information flow), to use RTCP protocols to ensure the quality of service.

IV. system hardware and software

1. system hardware

Here we give the more complex the gate terminal, its hardware architecture as shown in Figure 3.

　　

　　

When the door Terminal detects that a key is pressed, the key information is synthetic frames format and 485 sends to hierarchy.

At the entrance door of the terminal of the camera is the start of the key, the video signal is sampled and sent to the DSP chip for compression. Compressed video stream in RTP and the final packaging, H.225 Protocol through the Ethernet port to send to the network.

Join in on all 485 tiered will receive to the door Terminal from the signal, but only the call of the layer will handle the information received, the CPU is forwarded to the appropriate user terminal.

2, software implementation

In software design consists of two parts, one is monitoring terminal monitoring software, another

It is all about the underlying software. Monitoring terminal using a multi-threaded software design methods, the system for connection of each control point total employs six thread, that is, the network monitoring thread, sending thread, accept thread, H.26 3 image decoding show thread, image save thread and record information (gate terminal dial, card access control and logging information) detection thread, as shown in Figure 4.

　　

　　

Monitoring terminal thread started by door Terminal is triggered.

When the door Terminal detects the key pressed, immediately to the network send broadcast command; when monitoring terminal after listening to a broadcast message, start the accept thread started to accept video streams, and the corresponding boot display threads and image save thread.

For the underlying software, is the door Terminal control software, its workflow, as shown in Figure 5.

The gate terminal power after initialization, and then start scanning button and card information, when you recognize the change, the microprocessor CPU l give tiered for sending a frame information, and listen to the feedback of the hierarchy, while at the same time start the DSP through network port to send a broadcast message to the Terminal, in order to start monitoring terminal accept thread accept video flow and access information or card information. When more than l min or end key is pressed, both parties to terminate the communication, the gate terminal and Terminal triggered by CPU1 between DSP interrupt to stop sending video streaming data.