Hierarchical anchoring of motion fields for fully scalable video coding

Traditional video codecs anchor motion fields in the frame that is to be predicted, which is natural in a non-scalable context. In this paper, we propose a hierarchical anchoring of motion fields at reference frames, which allows to “reuse” them at finer temporal levels - a very desirable property for temporal scalability. The main challenge using this approach is that the motion fields need to be warped to the target frames, leading to disocclusions and motion folding in the warped motion fields. We show how to resolve motion folding ambiguities that occur in the vicinity of moving object boundaries by using breakpoint fields that have recently been proposed for the scalable coding of motion. During the motion field warping process, we obtain disocclusion and folding maps on-the-fly, which are used to control the temporal update step of the Haar wavelet. Results on synthetic data show that the proposed hierarchical anchoring scheme outperforms the traditional way of anchoring motion fields.