【作者】 田华娟；

【导师】 成运； 张荣湘；

【作者基本信息】 湖南大学 ， 软件工程， 2010， 硕士

【摘要】 本文研究内容主要围绕着最新视频编码标准H.264/AVC中的帧内编码算法和帧间编码算法两部分展开的。帧内编码和帧间编码是视频编码的重要组成部分,目前这两部分的算法过于复杂,不适合应用于对实时性要求较严格的领域。本文针对于这两部分存在的问题,对预测策略进行了改进,分别提出了一种快速算法,通过改进后的快速算法能够有效的降低计算复杂度,提高编码效率。基于此,本文进行了如下的研究工作：首先研究了视频编码标准的发展,H.264标准的系统组成、帧间预测、帧内预测、整数变换及量化、熵编码、率失真优化等关键技术。其次,对现有的H264的帧内预测模式算法进行了详细的分析。利用相邻块的预测模式之间的相关性以及相关预测模式之间编码的特点,提出了一种基于阈值的快速帧内模式选择算法。该算法可以根据阈值,确定是否可以将最可能的预测模式作为最终的预测结果,排除大量的无用的帧内预测模式,避免了很多不必要的代价计算。最后,经过大量的编码实现和实验,以及与原始算法的对比表明,该算法能有效降低帧内预测的复杂度,同时基本保持了H.264的编码性能,并且具有很好的自适应性。最后,对已有的快速帧间模式选择算法进行分析和研究后,利用3种典型帧间块编码模式的率失真优化值的单调性提出了一种快速的帧间块编码模式选择方法,而对于P帧编码来说,在确定了最佳帧间块编码模式后还需要与最佳帧内块编码模式下的率失真优化值进行比较,以便确定待编码的帧间块最后是选用帧间还是帧内编码模式,为此,又提出了一种快速的帧内是否需要帧间编码模式的判决方法。把以上方法综合运用到H.264编码器中,大大降低了其模式选择算法实现的复杂度。更多还原

【Abstract】 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.更多还原