Design And Implementation Of Network Camera Based On DSP

With the developing of computer technology and image processing technology, the simple text and sound information in traditional monitoring system can not match the need of people. The accepted developing direction of video monitoring system is to be more digital, networking and integrated. The network camera system is a new generation monitoring system, which is the combination of computer technology, image processing technology and communication technology. It represents the tide of monitoring system.At present, there are various solution schedules of network camera system in the market. Traditional network camera systems are usually based on PC or workstation platform, the implements of system video encoding and network transmitting depend on software entirely, and there are commonly some disadvantages such as high configuration demanding of system in these systems. The preferred schedule of most embedded systems adopts SCM as the core of the system. Because of plenty periphery equipments integrated on chip, SCM has good control ability. But such schedule only adapt to these situation which have low amount of data processing and operation.There are also much security problems in existed network camera system, such as having no safety protection in transmitting of secret information, which may damage the benefits of corporation, society or the country. Now, most video devices adopt standard encoding format. Because of adopting these open standard arithmetic, the compressed information transmitted through network tend to be too easy to be resumed once being captured to ensure the security. It attaches importance to how to ensure the security and secret in video transmitting increasingly. It is the best choice to develop our own encoding and decoding algorithm. So, the network camera should have the ability of program and run our own algorithms.Digital signals processing technology develops rapidly, which make the performance of DSP become higher and lower cost continuously, and the technology regards as the hotspot of many industries gradually. DSP is the short form of Digital Signal Processing or Digital Signals Processor, it is a rising subject involved many other subjects and been widely used. In real-time signal processing, there are the virtues of reliability, stability, high precision, programmable, using repetitious and integration of DSP. DSP is a processor which has special architecture. DSP algorithm could be executed rapidly because of its Harvard structure which separates data bus from program bus, special multiplier, pipelining and special DSP instruction.Embedded system is a special computer system, which focus on application and based on computer technique, semiconductor technique and electronic technique. Its aim is to satisfy the consumption, function, security, cost and physical volume required by special application system.The system referred in this paper is based on embedded system technology and DSP, which has some strongpoint such as high rapidity, low cost and high security etc. This solution works as the alternative of the following: the traditional network camera system and the network camera system based on SCM. The former depends on computer, which results in some disadvantages such as the high cost, poor function in real time and unfit to common consumer etc and the latter has low amount of data processing and operation.DSP, the core of the system, we used is called ADSP-BF532 which is a general purpose DSP manufactured by ADI. Based on this core, we design the hardware, driver and software and make some optimization. The system design is parted into three parts: hardware design, driver design and software design. In hardware design, we part the system into five modules at hardware layer; they are the kernel module, the logic module, the capture module, the display module, and the network module. In every module, we introduce its function, chip-selection and the connection between the modules. In driver design, we introduce how to initialize the peripherals, and how to code correct read-write programs which used by ADSP-BF532 to communicate with the peripherals; we also introduce the inside logic of CPLD which is used as the logic controller when extending the peripheral interface of ADSP-BF532. In software design, we introduce the language transform, the work-flow of the system and network protocol implementation. The language transform is from the C++ language to the C language. In this part of network protocol implementation, we mainly introduce the implementation of every layer of UDP protocol of LwIP. At last, the system optimization method is given in three levels: the aspect of CPU, the aspect of memory and the aspect of I/O. The program after optimization could use the hardware resource more efficiently, which improves the real time ability.We achieve a sample machine about the solution given above. The system combines core DSP with sensor and exterior memory working together, then make local display and transmit the signals to the network port after conversing format of signals captured by the sensor. The corresponding end receives the signals transmitted though the net finally. The algorithm is solidified on the board; both the efficiency and stability are improved. Integration of image processing makes both the volume and the cost of production reduced. DSP-based applications are compatible to other devices based on modern digital technology and have convenient interface, can be connected to Ethernet directly. The developing can be flexible and the systems tend to be easy to debug and integrate by using programmable DSP.For the network camera is based on network transmission, so it could be used in remote video conference and monitoring, especially the monitoring of machine house and cargo storehouse without man works in. In addition, the system can be applied to police and court department, oil field and reservoir, environment protection and forest fireproofing wireless surveillance, wireless TV broadcast car and war industry etc, especially in outdoor environment such as in desert, border etc.