Rate-distortion and complexity optimized motion estimation for H.264 video coding

11.264 video coding standard supports several inter-prediction coding modes that use macroblock (MB) partitions with variable block sizes. Rate-distortion (R-D) optimal selection of both the motion vectors (MVs) and the coding mode of each MB is essential for an H.264 encoder to achieve superior coding efficiency. Unfortunately, searching for optimal MVs of each possible subblock incurs a heavy computational cost. In this paper, in order to reduce the computational burden of integer-pel motion estimation (ME) without sacrificing from the coding performance, we propose a R-D and complexity joint optimization framework. Within this framework, we develop a simple method that determines for each MB which partitions are likely to be optimal. MV search is carried out for only the selected partitions, thus reducing the complexity of the ME step. The mode selection criteria is based on a measure of spatiotemporal activity within the MB. The procedure minimizes the coding loss at a given level of computational complexity either for the full video sequence or for each single frame. For the latter case, the algorithm provides a tight upper bound on the worst case complexity/execution time of the ME module. Simulation results show that the algorithm speeds up integer-pel ME by a factor of up to 40 with less than 0.2 dB loss in coding efficiency.Publisher's Versio

Fast Mode Prediction for the Baseline and Main Profiles in the H.264 Video Coding Standard

We propose a novel fast mode decision scheme for both the baseline and main profiles of the H.264 video coding standard. Our scheme combines a set of conditions for SKIP mode decision, two heuristics that reduce the set of intermodes to be examined, inter/intramode prediction and the monotonicity property of the cost functions. For very similar RD performance, we achieve (33%-90%) reduction in run times as compared to H.264. Compared to other work that was used as input to the standard, our scheme is faster by 9-23% for very similar RD performance. The proposed scheme can be used either in its entirety or as individual components for speeding up the standard. It can be also used in conjunction with fast motion search methods and is applicable in both the rate controlled and non rate controlled cases of H.26

Diseño de un algoritmo rápido para decisión de modo en H.264

El último estándar de codificación de vídeo H.264 supone una mejora respecto a sus predecesores en los que respecta a eficiencia de codificación, pero lo hace a costa de un aumento del coste computacional. Esto supone una dificultad para su utilización en aplicaciones de codificación en tiempo real. El presente Proyecto Fin de Carrera pretende lograr una reducción en el tiempo de codificación de una secuencia de vídeo, intentando que este proceso no suponga un deterioro significativo en la calidad, ni un aumento en la tasa necesaria para su codificación. Para ello se centrará en el problema de la decisión de modo. ____________________________________________The last standard in video coding, the H.264, represents a significant improvement in comparison with its predecessors in terms of coding efficiency but at the expense of a higher computational cost, which means a drawback in its use in real time coding applications. The objective of this Master Thesis is to obtain a reduction in the time needed to code video, without a noticeable loss in quality, and avoiding an increase in the bitrate needed. In order to do so, it will tackle the problem of mode decision.Ingeniería de Telecomunicació

Mode decision for the H.264/AVC video coding standard

H.264/AVC video coding standard gives us a very promising future for the field of video broadcasting and communication because of its high coding efficiency compared with other older video coding standards. However, high coding efficiency also carries high computational complexity. Fast motion estimation and fast mode decision are two very useful techniques which can significantly reduce computational complexity. This thesis focuses on the field of fast mode decision. The goal of this thesis is that for very similar RD performance compared with H.264/AVC video coding standard, we aim to find new fast mode decision techniques which can afford significant time savings. [Continues.