The Video Mixing Module Design And Research In Multimedia Conference Based On MIPS

Multimedia conference is a kind of multimedia communication meeting, it uses network to transfer video and audio information. In TV conference, many attendees in two or more different locations can receive the voice and image of each other, it makes user feel like in the same venue to attend the meeting, this communication mode improve the working efficiency significantly. Video conference system research work has been conducted early in the70s last century, Domestic research is later. At present domestic video conference system is mainly applied in government departments, indexes of information construction is also one of the important content of each enterprise. In work and enterprise environment, e-mail and telephone is standard approach to solve problem, but with video communication provide face to face techonology will improve the efficient way to solve problem, so the video conference system will be a very important means of communication to solve problem. But in the practical application of video conference system, we will usually meet that the images are not clear, sometimes video and audio transmission will have a long delay, the speaker’s an expression may have been delayed several seconds to appear, these disadvantages serious impact the video conference and the personnel’s communication efficiency. Therefore improve the efficiency of the system software and enhance the real-time became the focus of this topic research.This research topic based on MIPS (Million Instructions Per Second) structure of the video conference system, on the basis that the single image displays correctly, we increased Video Mixing module, Video Mixing module is used in mixing many of the images after multi-decoders module. This module will make the system support multiple YUV video data processing road, so that it will achieve a target that one screen can display more images. In the research project, development platform is based on the PLM3000MIPS architecture development board. Our purpose is that the design can make the execution of the mixing module the highest efficiency, to minimize the delay. Through the comparison of the different design, we can select the best plan.Module need support functions include many road input and single output, the number of road of input can be change by users anyway, the output size can also be arbitrary designed; Every road image position can be arbitrary put, and shear away the part which is beyond the boundary; Support multiple sampling formats and storage formats, and support the format conversion between different YUV; Support when one way video node has no data, do not free memory and repeat a image copy until received new data, this can avoid showing the empty diagram.On the basis of the realization of all functions, this topic must improve the efficiency, because the biggest problem in current video system is the video and audio transmission delay, large time delay will affect the personnel’s communication efficiency, thus increasing the data copies efficiency of the software realization, improve real-time became the focus of this topic research. We compared the efficiency between the choices of the data transmission method and the multiple unified handles of YUV sampling format, we may safely draw the conclusion that using data copy method with DMA has higher efficiency than using CPU data copy method, Finally we choose a relatively efficient scheme.