Jointly optimal inter-mode shape coding and VLC selection
This paper investigates how the between frame correlation of shape information can be exploited within the framework of an operationally rate-distortion (ORD) optimized coder. Contours are approximated either by connected second-order spline segments, each defined by three consecutive control points, or by segments of the motion-compensated reference contours. Consecutive control points are then encoded predictively using angle and run temporal contexts or by tracking the reference contour. We employ a novel criterion for selecting global object motion vectors, which further improves efficiency. The problem is formulated as Lagrangian minimization and solved using Dynamic Programming (DP). Furthermore, we employ an iterative technique to remove dependency on a particular VLC and jointly arrive at the OPD globally optimal solution and an optimized conditional parameter distribution.