Design Of High-definition And Low-delay Video Overlay System Based On FPGA

As more and more video image information needs to be processed and perceived in the video synthetical graphical display system,and multiple images need to be displayed on the same display device,video overlay technology becomes the key to solve the problem of multiple image fusion.In many video overlay applications,higher technical requirement of the delay of overlay and the definition of image are required,for example,cockpit display system of aircraft.And the unstable delay of embedded operating system limits its application on real-time video processing platform.Therefore,a high-definition and low-delay video overlay technique is needed to satisfy application requirements of video overlay system on real-time video processing platform.Through the analysis of architecture and overlay performance of video processing system,this paper proposes an overlay scheme with characteristics of high definition and low delay.First,the input image details are preserved and the noise of the input image is suppressed by introducing a two-phase multistage image enhancement unit based on median filter.Secondly,in order to realizing the efficiency of image scaling and ensure the clarity of the details edge,we change the calculation method of the corresponding gray image edge by optimizing piecewise weighted linear interpolation algorithm based on even-odd decomposition.Then,an adaptive multi-pipe interpolation scaling array that the spare interpolation module can be work as row interpolation or column interpolation function according to amount of row or column have finished is designed to reduce the latency of scaling processing,which realizes synchronous scaling of multiple row or column data streams and reduces the scaling delay.Finally,two input image and mouse cursor are overlayed through a two-stage pipeline-type fusion overlay device based on the ping-pong operation,and the overlay image is transmitted through the image output controller.In this paper,the modeling of the the system and simulation of function is completed first,followed by the system verified based on XILINX A7 hardware platform.By overlaying two input video images with 1080 p resolution,the results show that the system can achieve scaling at any scale of the overlay image,while the PSNR(Peak Signal to Noise Ratio)of the overlay image is up to 35.4624 d B,and the actual delay of video image overlay is as low as 16 ms.There is no drag phenomenon when human eyes observe the movement of the overlay image,which can meet the application of video overlay with low delay and high definition.