Research And Realization Over Seamless Switching Technology Of SP-frame In H.264 Standard

Due to the explosive growth and great success of the Internet, as well as the increasing demands on video services, streaming video over the Internet has drawn tremendous attention in both academia and industry in recent years. In order to meet compression efficiency and network friendliness, H.264 video compression standard introduces an extensive set of new features, including SP(and SI) coding technique. The primary feature of the SP (Switching Predictive-frame) technique is that SP-frame allow identiacal frames to be reconstructed even when they are predicted using different reference frames. In consequence, adopting SP technique to produce media streams, the server dynamically switches seamlessly between the streams to accommodate the variations of the bandwidth available to the client.This thesis is about to demonstrate the designing and realization process of a stream codec system, that can achieve seemless switching between streams.1. achived seamless swithing, the key application of SP-frame Again assume that there are two bitstreams corresponding to the same sequence encoded at different bit rate. Within each encoded bitstream, SP-frame are placed at the locations at which switching from one bitstream to another will be allowen. These SP-frames shall be referred to as primary SP-frames in what follows. Furthermore, for each primary SP-frame, acorresponding secondary SP-frame(acting as switching frame) is generated. JM software model of H.264 standard have just realized the codec scheme of primary SP now, and can only code one stream once. However, secondary SP frames have never been realized, as well as coding environment setting scheme and coding algorithm scheme. This thesis starts from the rude frame drawing of coding secondary SP frame described in the JVT proposal, aimming the target of "switching seemlessly", and performs a particular coding scheme of "copy" to code intra macroblocks and uses new frame to code inter macroblocks. At the same time, we considered the applicability of particular coding scheme of "skip" mode and the update of deblockor, and then designed an algorithm of coding secondary SP frames in detail.2. proposed a high-effictive intelligent file framework Starting from thekeystone of "fast and precise", for different basic stream blocks with different bitrates, frame blocks for switching between streams, key frame blocks, the framework performs a proper arrangement. High-effictive intelligent files produced in such a framework have the features of clear structure, easy management, applicablebility for common stream media servers. As the result, it realized a system with features of "producing multi-stream media in different bit rates at once" and "switching between streams seamlessly". At the end of the thesis, the summary is given and the researching content at next step is proposed.