Research On Intelligent HD Video Conferencing Terminal

Video conferencing is a kind of multimedia communication with rapid development in recent years. Video conferencing terminal is an input device of a video conferencing system, and it plays an important role throughout the system. It is a user-oriented device, which reflects the performance of the video conferencing system. Currently the most market share of video conferencing terminals is occupied by foreign companies, while video conferencing terminals are still in early stages of development in China. High-definition and intelligent are Focus Points for the various manufacturers and they are also the inevitable trend of development for Video conferencing.This thesis reviewed the development and application of video conferencing, the important role of the video conferencing terminal in the video conferencing system, the development status of HD video conferencing intelligent terminal. Then this thesis described the main contents that were to do theoretical research on some related issues for HD video conferencing intelligent terminal and to come up with solutions and finally to design and debug each functional modules.The research on HD video conferencing intelligent terminal included some important elements as follows: PTZ 2-DOF rotary mechanism, Stepper motor control, OSD, HDMI interfaces, external communication, preset and self-learning scan functions , the screen targeting functions, etc.PTZ 2-DOF rotary mechanisms are the main mechanical structures of intelligent terminals. Having learned from experiences in others products, combined the present condition of the domestic processing, and considered product stability and cost estimates, some innovations and improvements were made, then some checking analysis were did by the 3D software modeling method.Stepper motors are mechanical power components widely used in recent years mechanical power components. Subdivision control principles were analyzed and they greatly improved positioning accuracy and improved the stationarity and reduced noise.OSD is the necessary function to achieve user-friendly operation of Video conferencing terminal. Basic principles of OSD were introduced and OSD programs were designed, and then screen menu functions were designed and debugged.HDMI is one of the mainstream HD video interfaces. Coding and output principles of HDMI were analyzed, and HD analog components were converted to a specific format of the digital code.External communication includes wired ways and wireless ways. In this thesis, serial communication was used as the wired way, and three common protocols command formats and decoding processes were introduced. Infrared remote was used as the wireless way, and principle of the infrared pulse-width modulation and IR decoding were introduced.Preset and self-learning scan functions have important applications in the HD video conferencing intelligent terminal. After analysis and comparison, the main ways to improve the accuracy of preset and the most optimal design method for data storage of self-learning scan function were proposed. Screen Targeting is an emerging intelligent and practical features meeting the objectives of the users to quickly select and view the target on screen. This feature is essentially to establish correspondence between the spatial coordinates and pixel coordinates of one fixed-point, which related to coordinate system transformation, camera model, camera calibration, etc. Based on these theories, a simplified calibration method for a PTZ camera has been proposed and in this way Screen Targeting was achieved.Finally, a summary is given for the whole thesis, and some suggestion about research direction is proposed.