Visual Media Coding and Transmission

6.2 MVC Encoder Complexity Reduction using a Multi-grid Pyramidal Approach

6.2.1 Problem Definition and Objectives

Multi-view Video Coding uses several references to perform predictive coding at the encoder. Furthermore, motion estimation is performed with respect to each reference frame using different block search sizes. This entails a very complex encoder. The goal of the contribution is to reduce the complexity of the motion estimation while preserving the rate-distortion performance.

6.2.2 Proposed Technical Solution

The complexity reduction is achieved by using so-called Locally Adaptive Multi-grid Block Matching Motion Estimation [20]. The technique is supposed to generate more reliable motion fields. A coarse but robust enough estimation of the motion field is performed at the lowest resolution level and is iteratively refined at the high resolution levels. Such a process leads to a robust estimation of large-scale structures, while short-range displacements are accurately estimated on small-scale structures. This method takes into consideration the simple fact that coarser structures are sufficient in uniform regions, whereas finer structures are required in detailed areas. The method produces a precise enough estimate of the motion vectors, so that the prediction efficiency is maintained with a less complex structure than a classic full search method. On the other hand, the coding cost increases, since the amount of side information becomes larger.

The multi-grid approach ...