Deployment of Constrained Delaunay Mesh in Vop Shape Coding

Abstract

The work presents an alternative method for encoding shape-information of video objects, which is a new requirement in the recent revolution of video codec scheme: compressing and transmitting object-based video streams. The proposed method takes the advantage of the latest development in the video encoding -motion compensation on the base of mesh presentation of frame -to complete its target. The so-called constrained Delaunay mesh is deployed to represent video objects, which are detected from a previous video object detector (in a consistent case of scene, detector can simply function like a segmenting phase of video frame). This special mesh structure in one hand constructs the base for successive motion compensation taking root on mesh-vertices. In another hand, the virtue of constrained property opens a possibility to encode the shape of video object implicitly, therefore it reduces the amount of transmitted information. With constrained Delaunay mesh, shape information of objects is presented with polygon, therefore lossy. The problem can be alleviated by increasing the number of boundary vertices at the cost of bandwidth. The work also puts a stress on controlling this trade-off. Results of integrating the proposed method into a full VOP codec scheme are encouraging.