Research On Fast Mode Selection Algorithms For H.264

This paper focus on Intra and inter-frame coding algorithms of the latest video coding standard H.264/AVC.Intra-frame coding and inter-frame coding are important part of video encoding.Currently,these two algorithms are too complex and not suitable for real time video coding.For in these issues,this paper improves the prediction strategy and proposes a fast algorithm respectively.The improved fast algorithm can effectively reduce the computational complexity and improve coding efficiency.In order to achieve high encoding efficiency, H.264 uses a great deal of encoding algorithms with high complexity. These complexity algorithms will limit the application of H.264 in real time video coding.So we must find corresponding fast algorithms to replace those with high complexity in H.264 reference software. According to above ideas, this dissertation gives deep research on Fast Mode Selection Algorithms and the implementation of H.264 encoder under the reference in PC with high speed and efficiency.According to the above ideas,this dissertation conducts the following studies Firstly, we researched the development of the video coding standard and discuss the key technique of H.264, including system composition, inter-prediction, intra-Prediction,integer transform,entropy coding, rate distortion optimization and so on. Secondly, we analyze the existing intra prediction mode algorithm in detail,we propose a fast intra mode selection algorithm based on threshold by utilizing the relationships of prediction modes of neighbor blocks and the coding characters of the relevant prediction modes.Based on the threshold,this algorithm can determine whether the most probable mode can be selected as the final forecasting resul,and it excludes massive useless intra prediction modes and avoids many unnecessary computations about costs. In the last, by having many times of coding accomplishment and experiments,and comparing with the original algorithm,it can be demonstrated that this algorithm can decreases the complexity of the intra prediction effectively, at the same time,it maintains the coding performance fundamentally, and has a favorable adaptive ability.Finally,through analysis of the existing fast intra prediction mode algorithm, this paper propose a fast inter-frame block coding mode selection method by using the monotonicity of the optimized value of rate-distortion of three typical kinds of inter-frame block coding modes.But for the P-frame coding, Comparison with the optimized value of rate-distortion of The best intra-block coding mode is needed after determining the best inter-frame block coding model,in order to determine the block to be encoded with inter-frame or intra-frame coding mode.The complexity of H.264's mode selection will be grately reduced when the above methods are adopted.