Motion Vector Field Analysis in Motion-Assisted Rate Control for H.264

Motion vector field analysis in motion-assisted rate control (MARC) helps us interpret the relationship between a distribution of motion vectors and its visual characteristics. In our earlier work, we showed how MARC utilized this relationship into an effective rate control method that enhanced subjective quality of regions with high visual sensitivity. In this work, we extend our initial idea further to enhance its performance. First, visual features of interest are defined in the sense of local distribution of pre-filtered motion vectors and their relationship with human visual sensitivity is discussed. To estimate the degree of this sensitivity, two simple and effective motion metrics are designed and their performance is evaluated on an MARC-enabled H.264 video codec. The calculation overhead is minimal, since motion vector information is already provided by the H.264 video codec. Our result shows that MARC reduces temporal PSNR fluctuations across frames while it improves the subjective quality of visually sensitive regions.