Design and implementation of a hybrid remote display protocol to optimize multimedia experience on thin client devices

In a thin client computing architecture, application processing is delegated to a remote server rather than running the application locally. User input is forwarded to the server, and the rendered images are relayed through a dedicated remote display protocol to the user´s device. Existing remote display protocols have been successfully optimized for applications with only minor and low-frequent screen updates, such as a spreadsheet or a text editor. However, they are not designed to cope with the fine-grained and complex color patterns of multimedia applications, leading to high bandwidth requirements and an irresponsive user interface. In this article, a hybrid remote display protocol approach is presented. The existing Remote FrameBuffer protocol of Virtual Network Computing (VNC-RFB) protocol is leveraged with a video streaming mode to transport the rendered images of multimedia applications to the client. Dependent on the amount of motion in the images to be presented, the images are relayed to the client either through the VNC-RFB protocol or through video streaming in the H.264 format. The architecture of this hybrid image renderer is presented and the implementation is detailed. Furthermore, the decision heuristic to switch between the VNC-RFB and the streaming mode is discussed. Experimental results clearly show the advantage of the hybrid approach in terms of client CPU and bandwidth requirements.