FPGA Design Of Video Mixing And Graphics Overlay

Video graphic process function is an important part in military-used graphic display and control system. To ensure that system can work stably in complex and bad war field environments, special designs for that system should be made, aimed at improving the system stability, security and robustness under possible extreme bad occasions in war field.There are some special video chipsets which can provide video process functions. But most of that chipsets are of commercial level, which can not meet the environmental demands. While there are many FPGA chipset of commercial, industrial and military level available, and the design of FPGA is very easy to change structure, and can be widely used. Also the FPGA is very good for model design, and suits real-time signal process because the develop period is short and the system is ease to maintain and extend.The main tasks of this thesis are as follows: Firstly, analyzing FPGA design tools and video overlay theory, including FPGA developing flow, Verilog HDL program. Secondly, expatiating the four modules of video overlay FPGA, that is: YCbCr video processing module, SDRAM control module, video overlay & output module, and control & interface module. Finally, simulating the system waves by the software of Modelsim, and integrating the video overlay module by Quartus II.The design in this paper converts both PAL analog signal and 18-bit LVDS signal to digital video signal by video capturing chipsets, overlays the two signals in FPGA, and displays the overlaid video in LCD.There are four modules in the FPGA. 1) YCbCr video stream process module, which converts the signal from YCbCr to RGB, and processes graphics including Gamma adjusting and image sharpening. 2) SDRAM control module, which controls frame buffer device, interfaces and arbitration. 3) Video graphics overlay & output module, which overlays the graphics, creates HS, VS signal, outputs digital RGB signal to D/A device. 4) Peripheral equipment interface module, which communicates with main computer, gets the graphics overlay control demands and adjusts video parameters.Experiments show that overlaid video by this design is very clear. All the work including hardware and software debugging for this design has finished, and this design has used well in an airplane cabin graphics display system.