Research On H.264 Intra Prediction Optimize And Intra Directional Prediction

With the development of information technology in 21st century, there grows the need of storing and transmitting video information efficiently. The property of digital video limits the expansion of multimedia services, so it is necessary to develop techniques for compressing these vide data. H.264 standard is jointly being made by ITU-T Video Coding Experts Group and ISO/IEC MPEG Video Group, named as joint video team (JVT). It is a highly compressed digital video codec standard.The characteristic of H.264 standard can be concluded mainly into three aspects. It is more practicable, more adaptive to IP net and mobile system and it improves the key components of coding structure based on hybrid video coding framework. For example, it adds coding mode decision, multi frame prediction, context-based adaptive variable length coding (CAVLC), 4×4 integer transform, loop filter, etc. The improvement in performance leads to higher computational complexity in the new standard. The complexity of H.264 encoder is about 3 times of H.263 encoder and the complexity of its decoder is 2 times of H.263 decoder. The optimization of H.264 codec is important for its application in different fields.Firstly,this paper discusses the basic principle and the essential technologies in H.264 video coding standard. Do some research and analysis on the complexity and real-time ability of H.264 intra prediction modes. Secondly, after researching on the related fast algorithm of Intra prediction, the thesis put an efficient method forward, determine whether carry out the Intra₄×4 prediction or not by comparing the result of the Intra₁6×16 prediction with the threshold. It could not only improve the coding efficiency, but also decrease the coding time. By having many times of coding accomplishment and experiments, and comparing with the original algorithm, it can be demonstrated that this algorithm can reduce the coding time by 20% at the same time it maintains the coding performance as H.264. Finally, analyze on the prediction ability of directional intra 4×4 prediction modes. It indicates that the different intra prediction modes have different prediction abilities. In order to solve this problem, a changed codec reordering strategy is proposed to codec the poor ability intra prediction mode. Theory analysis and experiments show that the method can improve the ability of the weaker intra prediction.