Model based analysis for quantization parameter cascading in hierarchical video coding

Originally, hierarchical prediction structures were proposed to achieve temporal scalability. Soon after, it was realized that with a proper quantization parameter cascading (QPC) scheme the general performance can be significantly improved by hierarchical coding. However, the theory behind the gain has not been explored so far. In this paper, the QPC in hierarchical coding is investigated by model based emulations. From the analysis, it is noticed that a parameter ß which represents the error propagation in a group of pictures greatly affects the performance of QPC in hierarchical coding. Based on ß, a simple adaptive QPC algorithm is designed. Simulations verify the efficiency of this algorithm: a gain up to 0.89 dB is obtained over the most recent SVC reference software.