Design And Implementation Of Video Overlay System Based On FPGA

With the rapid development of technology, video image processing has got a lot of attention and been widely used in today’s information society. Video overlay is an application of video image processing and can makes multi-channel and multi-format video signals blend together to become one video signal to output to one display device. This technology plays an important role in the field of television system, security surveillance system and airborne integrated display system.In this paper, an analysis of the different formats and transmission of video signals is made and the key algorithms of video overlay of multi-channel and multi-format is studied, including deinterlacing of TV video, image scaling and video overlay. On this basis, a video overlay system is designed and implemented. In this system, FPGA is used to implement the algorithms as a core processor. DDR2 SDRAM is used as the cache of video data. TW2867 which supports the acquisition of four composite video broadcast signals is used as video input module. The blended video signal output through VGA interface and the video overlay processing is controlled by the STM32 microcontroller. The design of the system is divided into two parts, including the design of the video overlay processor based on FPGA and the design of the system control software. The video overlay processor which is composed of the video input processing module, the deinterlacer, the video frame buffer control module, the video scaler, the video overlay and output module and the I2 C bus interface is implemented by logic design in the FPGA and processes the multiple input video signals to blend them together. The system control software which is composed of the I2 C bus driver, the communication program through the UART, the TW2867 video capture control program, the video overlay control program and the main control program runs on the STM32 microcontroller and controls the effect of video overlay in real time.The result of testing and verification indicate that the video overlay system designed in this paper meet the requirement and has a good performance. Two input videos are blend together to output to one computer monitor in the system. One of the two input videos is scaled to the size of the output video as the background and the other is transparently overlaid on the background as foreground. The video source of the background and foreground can be switched. The foreground video’s transparency, scaling size and position on the background can be adjusted. Results of the research and design in this paper have reference value for the study and engineering applications of video overlay technology.