Research And Implementation Of The Ims In Real-time Video Processing

IP Multimedia Subsystem designed by the 3rd Generation Partnership Project was first present in the R5 version. It is a general name referring to logic functional entities that are responsible for controlling the IP multimedia business at the core network. Through mechanisms such as the network of authority and resources reservation, IMS is able to achieve quality of service, support the new services and applications of voice, data or multimedia. IMS supports the integration of cable and wireless access to construct a single foundation of telecommunications network, mobile terminals can seamlessly access the various IMS-based services for customer.Research shows that more than 50% of the effective information comes from the visual communication. Providing the information including video content is always the potential force of development of telecommunication. 3G initiates a new era for integrating the wireless communications and Internet. The wireless IP-based multimedia business must become the growth point of profit for telecommunication industry. Transmitting real-time video with certain QoS is the main task of multimedia applications. Wireless channel is a time-varying, poor ability of anti-jamming, limited-bandwidth channel. Worse, mobile terminal is also of limited computing ability. The traditional video encoding and transmission technology is facing new challenge. With applying the Service-Base Local Policy to overcome the shortcoming of wireless channel, IMS can assure IP business acquires the enough resources in the access network and core network.This thesis is derived from "Multi-Media Client" project developed by a communication company. They implement an IMS-based multimedia conversation system. It communicates with the Streamed Multi-Media application server placed at the core network through SIP to establish the end-to-end multimedia conversation with certain QoS. It aims to verify the feasibility and availability of IMS in 2.5G, while assessing the business value brought by IMS in 3G era. The author is mainly responsible for the development and implementation of real-time media stack in the project, including video input, video coding, video transmission and video playback. To simplify the system design, the author used two development kits provided by open source project in the critical video encoding and video transmission. Considering the special characteristics of our system, the author optimized the bit rate control algorithm by replacing SAD with MAD to reduce the complexity and processing time of the encoder, and introducing sliding window for frame selection to smooth image quality. To make the thesis clearer, the author omits or simplifies the design and implementation of session management, user/group management and GUI, mainly analyzes and discusses the QoS mechanism of IMS and video processing technology supported by mobile terminal. Combining the aforementioned functions, i optimize the bit rate controlling, and an IMS-based real-time video application prototype is implemented.