Research And Implementation Of Cloud Video Technology Based On VNC Protocol

With the development of cloud computing, the pattern of delivering IT infrastructure are well received by the public, and another revolution in computer science is coming. Encouraged by cloud computing, virtual desktop technology has flourished a lot. The scheme in which users’ PCs are under unified management of the server-side and they connect to the virtual desktops by remote connection, has become the basic principle realizing numerous virtual desktop products. And using multimedia applications via virtual desktops, especially playing high-definition video games have become a major challenge in implementing virtual desktop products.VNC is a software for screen sharing and remote operation using RFB protocol. It has become an excellent remote desktop sharing software due to its cross-platform, lowbandwidth and low CPU utilization. However, the performance of RFB protocol is not good enough while playing videos, thus it can hardly meet the need to watch video played on the server-side from the machine used as a client. It is exactly the purpose of this thesis to solve this problem. Firstly, this thesis describes the details of messages in VNC, methods of requesting screen refresh and methods of encoding images, and at the same time, it has analyzed the deficiencies of VNC. Next the thesis has proposed the improvement ideas. It applies the strategy of pushing updates from the server aiming at the issues of low screen refresh rate. For the problem of high bandwidth utilization caused by low encoding compression rate, this thesis uses H.264 coding scheme to reduce the amount of data transferred. Solutions were also put forward in this thesis for some details in the process of improvement:First, the concept of desktop mode and video mode are put forward to reduce consumption of resources when videos are not played and to optimize the experience when videos are played;Second, the frame rate self-adjustment scheme is proposed to improve the program’s adaptability to different configurations of machines, which guarantees relatively low CPU utilization in low-configuration machines and makes full use of machines’ performance in high-configuration machines;Then, the thesis implements the improvement based on Tight VNC by adding mode exchange module, server-side pushing module, frame rate self-adjustment module, encoding and decoding module.Finally, function testing and performance testing are done to validate the improvements are feasible. And the improved VNC is compared with Tight VNC in three aspects such as CPU usage, bandwidth usage and fluency. The thesis concludes that the improved VNC has made a significant progress both in bandwidth usage and fluency when playing video, however, it performs not as good as Tight VNC in CPU usage. In summary, the improved VNC can be applied to video display in cloud platform.