Video Encoder Output For Video Wall Controller Hardware And Software Design

This project serves the video wall system. The main purpose is to improve quality of video wall system's output, and let the output part not to depend on the costly import device, become a whole system which can directly output to the video wall. The final purpose is to find a scheme of video wall system which has high quality and low price,and push our video wall towards market. In the project, we used software simulation combining with hardware realization.In the step of theory research, we studied the image zoom methods closely relating to output effect of video wall controller. Firstly, we analyzed the traditional image zoom methods include nearest neighbor interpolation, bilinear interpolation, and discussed the scheme of their hardware realization. Then, we went deep into two new image zoom methods, optimized them and analyzed their complexity and hardware feasibility. We used MATLAB to process software simulation. Taking character and normal image as example, we contrasted the traditional and new image zoom methods mentioned above, and got the results of subjective visual comparison and objective evaluation. By the research of the new methods of image zoom, we find that the wavelet-based zooming method with enhanced coefficients and the pixel-exchanged-interpolation method with median filter are two excellent image zoom method, and they exhibit visible subjective effect difference. We find that the former method is better than the later one in zooming general images; and the later method is better than the former in zooming characters. This is due to the inherent distinctions between texts and general images. Texts have only two pixel luminance values, black and white. There is no closely relation between characters. It has clear edges and requires rather high definition of single character. General images need clearness and smoothness of a whole image, the pixels are related one another, and have many luminance value grades. We analyzed the principles of them,and put forward the idea that based on the character of image to be enlarged, flexibly choosing appropriate zooming method to achieve optimal zooming effect. Then we put forwards a real time scheme to use the two methods mentioned above alternatively.Based on the image zoom theory, we designed a relatively simple circuit of TV wall video encoding output. The part of image dividing and zooming are realized by FPGA. Based on an IC named CX25870, we designed the part of D/A, and made a free-flicker video encoding output circuit. We synthetically used Microcomputer System, FPGA and I2C bus application system design.During the process of hardware and software debugging, we successfully resolved the problem of digital switching noise eliminating, erratic device behavior, instability of clock frequency, new problem caused by horizontal and vertical Sync generation, etc. We also advanced method to synchronize the digital data of master and slave device.