基于H.264的自适应选择增强FGS视频编码

Adaptive Selective Enhancement FGS Video Coding Based on H.264

提出了一种新的选择增强FGS编码方法,基本层仍采用H.264编码方式,增强层直接利用基本层的模式判决结果对不同运动分割宏块进行不等程度的增强.H.264采用了树型结构运动补偿,较大的宏块分割尺寸适用于平坦区,而较小的宏块分割尺寸可以刻画精细的运动细节;分析表明,对于特定类型的图像序列,精细的运动细节又较为集中于视觉感兴趣区(ROI).本文利用这一特点,对较小分割尺寸的宏块进行位平面提升以保证精细运动细节区的优先编码,使它们更容易被包括进截断码流,从而在不必预先确定ROI位置的条件下仍能有效提高ROI的重建质量.

A new method of selective enhancement for FGS is proposed, in which the base layer is encoded with an H.264- compliant encoder, while the enhancement layer, by using the outcome of mode decisions within the base layer, is encoded after performing unequal enhancement on motion compensated sub-blocks of varying partition size. H. 264 uses tree-structured motion compensation featuring a tlexible hierarchy of partition sizes. In general, a large partition size is appropriate for homogeneous areas of the frame and a small one may be beneficial for motion detailed areas. Analysis shows that, for image sequences with particular characteristics, Region-of-Interest （ROI） may contain a significant part of areas with high motion detail.3~nis feature can be used in W,S coding in which bit planes of macroblocks with small partition sizes are bit - shifted up prior to encoding in order to give them a higher priority and a higher probability of being included in a truncated bit stream, hence maximizing the quality of the potential ROI in the decoded sequence without the need to determine coordinates of the ROI in advance.