投影系统中屏幕共享技术的应用研究

发布时间：2018-01-11 14:12

本文关键词：投影系统中屏幕共享技术的应用研究　出处：《华南理工大学》2014年硕士论文　论文类型：学位论文

【摘要】：随着计算机技术的发展和日常工作生活中人们对屏幕共享需求的优化，各大厂家推出了电视盒子、电视棒等屏幕共享设备，实现了在局域网内电脑、手机等小屏幕计算设备与电视、投影仪等大屏幕显示设备的无线连接。例如家庭用户可以使用GoogleChromecast将手机或平板电脑上的视频通过WIFI传输到智能电视上观看。但这些类Chromecast设备局限在特定的硬件平台，且需要额外购买。在教室或会议室等需要投影仪展示等场合，投影仪的VGA或HDMI线缆长度和接口数量限制了主讲人计算机的物理位置和数量。同时对于不同厂商的投影仪，还存在兼容性问题。在教室或公司等办公场合中Windows操作系统用户居多，且已投资的硬件设备需要充分利用。因此，研究基于Windows操作系统的类Google Chromecast屏幕共享系统，在教室或会议室投影领域会有更大的施展空间。计算机屏幕共享包括屏幕图像的获取、编解码、传输和显示等过程，属于流媒体信息处理和传输领域，具有数据量大、计算复杂度高、实时性要求高等特点。把它应用于教室或会议室投影场合，需要高性能的屏幕图像获取技术、高性能的音视频编解码算法和处理能力强大的硬件平台。本文研究了基于Windows8的Desktop Duplication技术，用于快速高效地抓取计算机屏幕图像。实验证明该技术抓屏帧率大于40fps，且能够抓取计算机屏幕图像变化的区域，从而使抓取的屏幕数据量大大减少。本文提出了一种高性能编解码模型，该模型把屏幕图像分为视频运动帧和普通帧。视频运动帧采用H.264编解码，并基于不同硬件平台研究了H.264编解码硬件加速。普通帧分为文本块和图像块，文本块用YUV444格式采样然后再用熵编解码，以减少文本块的失真。图像块采用JPEG编解码，规避了H.264编解码的复杂性。实验证明其编码耗时小于22ms，解码耗时小于8ms，CPU占用率小于23.2%。基于以上高性能计算机屏幕抓取技术和编解码模型，本文设计并实现了一种基于Windows8操作系统的高性能计算机屏幕共享系统。实验结果显示，本系统显示延迟为200ms，CPU占用率小于11.8%，网络使用量小于3M，清晰度和流畅度各为95分（满分为100分），达到了教室或会议室无线投影要求的高清晰度、高流畅度和低延迟。
[Abstract]:With the development of computer technology and daily life sharing needs optimization on the screen, the major manufacturers launched a TV box, TV screen sharing equipment, the computer in the LAN, mobile phone and other computing devices with small screen TV, projectors and other large screen display devices such as wireless connection. Home users can the use of GoogleChromecast mobile phone or tablet computer through the WIFI video transmission to watch on a smart TV. But these Chromecast equipment limited to a specific hardware platform, and the need for additional purchases.
In the classroom or conference room to display projector and other occasions, the number of VGA or HDMI and the length of the cable interface projector limits the physical location and number of speakers. At the same time for different computer projector manufacturers, there are compatibility problems. In the classroom or other office occasions in the majority of Windows companies operating system users, and has invested in hardware the equipment needs to be fully utilized. Therefore, the research of Google Chromecast screen based on Windows operating system and sharing system, in the classroom or meeting room projection areas will have more display space.
Including the screen image acquisition, computer screen sharing codec, transmission and display process, which belongs to the streaming media information processing and transmission field, with a large amount of data, high computational complexity and high requirement of real-time. The application of it in the classroom or meeting room projection occasions, to screen high performance image acquisition technology, high the performance of audio and video codec algorithm and powerful hardware platform.
This paper studies the Desktop Duplication technology based on Windows8, used to quickly grab the computer screen image. Experimental results show that the technology of capturing frame rate is greater than 40fps, and can capture the computer screen image change area, so that the screen data capture is greatly reduced.
This paper presents a high performance coding model, the model of the screen image into video frames and ordinary frames. Video frame using the H.264 codec based on different hardware platform of H.264 codec hardware acceleration. The ordinary frame is divided into blocks of text and image blocks, a block of text in YUV444 format and then use sampling entropy coding, in order to reduce the distortion of text block. The image block using the JPEG codec, avoiding the complexity of the H.264 codec. Experiments show that the encoding time is less than 22ms, the decoding time is less than 8ms, CPU occupancy rate is less than 23.2%.
The high performance computer screen capture and decoding technology based on the model, this paper designs and implements a high performance computer screen sharing system based on Windows8 operating system. The experimental results show that the system display delay is 200ms, CPU occupancy rate of less than 11.8%, so that the network usage is less than 3M, clarity and fluency of 95 points (out of 100 points), reached a high definition classroom or conference room wireless projection requirements, high smoothness and low latency.

【学位授予单位】：华南理工大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TN946.1

【参考文献】