Hybrid scalable video codec for bit-depth scalability

Abstract

Scalable video coding, which is an extension of H.264/AVC, provides efficient methods for merging 8-bits/pixel sequences and higher bits per pixel sequences into one scalable bitstream. In this work, two types of prediction approaches are supported. One is based on interlayer intraprediction, by which texture residuals between the base layer and the enhancement layer are removed. The interlayer intraprediction is restricted to the enhancement macroblock whose collocated macroblock is intracoded. In this prediction structure, a global look-up table, obtained from an arithmetic average or scale offset pairs of each macroblock, is chosen as an inverse tone-mapping process, depending on rate distortion (RD) performance. The other is based on interlayer motion prediction, where motion compensation is performed in the enhancement layer as well as in the base layer. But motion parameters in the enhancement layer are inferred from the corresponding blocks in the base layer, which minimizes the complexity increase. A coding gain of 0.14 dB or 1.2% reduction in bit rate is obtained for 10 bits/pixel test sequences, while a coding gain of 12 bits/pixel test sequences reaches up to 4.2 dB or 48% reduction in bit rate.