| With the development of technology of electronic, communication and computertechnology, communication technology and technology of computer, the embeddedmultimedia processors are used popularly more and more.The embedded multimediaprocessors have the advantage of low-power, high-performance and have the dedicateddevice on the chip. The products using embedded multimedia processors are many, forinstance, embedded multimedia server and embedded multimedia terminal etc. They areput into use in many fields such as communication, transportation, bank and governmentetc. Now, with the more applications of embedded multimedia server and embeddedmultimedia terminal the more focuses are on the design and study of embedded multimediacircuit. Lots of researchs of these fields are putting forward in government and enterprises,etc.The thesis depend on the projects of jilin province "IP Network BandwidthSelf-adaption Multimedia Terminal Based on Sub-sampling Technology" and "EmbeddedMultimedia Server Based on H.264of IPV4/IPV6Network". The main research contentsare about the design of embedded multimedia terminal circuit and the research andimplement of the related algorithms based on the embeded CPU.The research contents are about the design of embedded multimedia circuit, design ofembedded multimedia circuit pcb, the optimizing of pcb on the basis of SI, the detection ofmoving object in the video image, shadow eliminating of moving object, digitalrecognition based on rectifying incline, the optimizing of algorithm structure, the driverdesign of the embedded multimedia CPU and the program design based on real-timeperformance on the DSP, etc. From the requirement of the project, a multimedia servercircuit based on embedded CPU and a multimedia terminal circuit based of DM642+FPGAis designed, the scheme, the circuit and the pcb had been designed. On multimedia server,the scheme is using ASIC for combining four channels video and using embeddedmultimedia CPU with video compress hardware on-chip. The circuit functions consist offour channels of video input port and four channels of audio input port, one channel videooutput port for local display, using H.264/H.263video encoding, communication on thenetwork, motion detection, osd, etc. The multimedia terminal uses the architecture ofmultimedia DSP+FPGA. The multimedia DSP is used for main control CPU, its functionsare video capture, video display, signal processing and network communication. Thefunctions of FPGA are realization of control logic, switch of VGA and composite videoand format conversion of video. The function of multimedia terminal circuit consist of twochannels of video input port, one selectable video output channel of VGA and compositevideo, a stereo input and output port, and Ethernet communication, etc. According to the SI theory and project requirement, rational layout and routing are made. The reflection andcrosstalk of SI analysis are done with the high speed signal. The topological structure isadjusted and the circuit is optimized. Using cascading resistance, it reduce the reflection,the overshoot and undershoot and meets the needs. From experiments, the circuits havefully functions and reliable performance, meet the design requirements.Some fundamental algorithm of in the video image processing is studied. They arecolor space transform，gray processing，threshold segmentation and interframe difference.The algorithms of moving target mark using rectangle is studied. Comparing the result ofsimulation, the application field is talked over between the algorithm of three frame andrectangle. The rectangle algorithm is suit video surveillance field. In HSV color space themotion detect algorithm of reducing the influence of shadow is studied. Using the featureof the influence of S component is small, the two times rectangle can reduce the influenceof shadow. The algorithm flow is optimized. First,using luminance get the first rectangle ofmoving target and its shadow. Then using S component get the second rectangle in the firstrectangle. The complexity is lowered and the algorithm can reduce the influence of shadoweffectively.The algorithms of digital recognition are studied when the object is inclining. Thealgorithm base on texture feature is used. Using the Rising and falling edge of the data tolocate and extract the area of the digital of the ammeter digital. The binaryzation ammeterdigitals are extracted using projection processing. A method of seven segments projectioncombined the particular position scanning is presented. If it is less positive and negative15degrees tilt, the digital can be recognized by this method with almost no mistake. And thismethod is not need the complicated operation of digital thining and coordinatetransformation. The aspect ratio is used to determine the digital "1".The top segment isused to determine the digital "4".The bottom segment is used to determine the digital"7".The lower right segment is used to determine the digital "2".The gap segment is usedto determine the digital "3","5","6"and "9".The mid segment is used to determine thedigital "0"and "8". The chart of classification and flow chart of digital recognition ofammeter are designed. The experimental results show that the algorithms are effective andnot complex.The video drivers are designed on the multimedia DSP DM642. From the features ofDSP, some functions of video processing are designed and the implementation of theprograms is discussed.The double words conversion, inline functions and L2cache for thedata often used are adopted. The key words of "const","restrict" and "volatile" are used.The algorithm flow of the detection of moving object in the video image which can reducethe influence of noise is optimized. The algorithm flow of the digital recognition forelectricity meter is optimized, too. The algorithms are implementation on the DSP. Theexperimental results show that the algorithms are effective and the implementation isrational. Above all, in this paper, two multimedia circuits are designed and some keytechnologies of multimedia circuit are studied. And the implementation about the relatedalgorithm on embedded CPU is the studied also. The circuit has fully functions and reliableperformance, achieves the expected requirements of the projects. |
PDF Full Text Request