可分级视频编码空域增强层的快速帧间模式选择算法

摘要

针对可分级视频编码(SVC)技术中层间残差预测(ILRP)大大增加了编码复杂度的问题,提出一种快速算法.带残差的帧间预测和不带残差的帧间预测都采用全搜索的预测算法,编码复杂度很大,所提算法分析了增强层带残差的帧间预测和不带残差的帧间预测之间的率失真代价(RDCost)差异,动态判定增强层是否需要采用层间残差预测以减少层间残差预测过程；同时依据层间预测模式相关性,利用基本层最优帧间预测模式指导增强层最优帧间预测模式的选择过程,进一步节省编码时间.实验结果表明,与参考模型JSVM中的算法相比,改进的快速算法在编码质量降低小于0.01 dB,码率提高不大于3％的前提下,可节省平均编码时间50％左右,有效地降低了编码复杂度,对于编码器的优化方面有理论参考价值和实际应用意义.%Inter-Layer Residual Prediction (ILRP) in Scalable Video Coding ( SVC) reduces the number of bits while significantly increasing the encoding complexity. To reduce the complexity, the paper proposed a fast mode decision algorithm. This algorithm analyzed the difference of Lagrangian Rate-Distortion cost (RDCost) when using residual prediction and not using residual prediction in enhancement layer. According to the difference ILRP was dynamically selected in the proposed algorithm. Meanwhile inter mode correlation between lower spatial layer and higher spatial layer was also analyzed. Based on the correlation the proposed algorithm used the best inter mode in lower layer to decide the best inter mode in higher layer and this would save more encoding time. The experimental results show that when compared with the algorithm in Joint Scalable Video Model (JSVM), the proposed algorithm can save more than 50% encoding time on average with neglected Peak Signal to Noise Ratio ( PSNR) change and small bit-rate loss. The proposed algorithm provides valuable references for further study of optimizing encoder.