Free viewpoint video (FVV) offers compelling interactive experience by allowing users to switch to any viewing angle at any time. An FVV is composed of a large number of camera-captured anchor views, with virtual views (not captured by any camera) rendered from their nearby anchors using techniques such as depth-image-based rendering (DIBR). We consider a group of wireless users who may interact with an FVV by independently switching views. We study a novel live FVV streaming network where each user pulls a subset of anchors from the server via a primary channel. To enhance anchor availability at each user, a user generates network-coded (NC) packets using some of its anchors and broadcasts them to its direct neighbors via a secondary channel. Given limited primary and secondary channel bandwidths at the devices, we seek to maximize the received video quality (i.e., minimize distortion) by  jointly  optimizing the set of anchors each device pulls and the anchor combination to generate NC packets. To our best knowledge, this is among  the first body of work  addressing such joint optimization problem for wireless live FVV streaming with NC-based collaboration. We first formulate the problem and show that it is NP-hard. We then propose a scalable and effective algorithm called PAFV (Peer-Assisted Freeview Video). In PAFV, each node collaboratively and distributedly decides on the anchors to pull and NC packets to share so as to minimize video distortion in its neighborhood. Extensive simulation studies show that PAFV outperforms other algorithms, achieving substantially lower video distortion (often by more than 20–50%) with significantly less redundancy (by as much as 70%). Our Android-based video experiment further confirms the effectiveness of PAFV over comparison schemes.
['Bo Zhang', 'Zhi Liu', 'Gary Shueng Han Chan', 'Gene Cheung']
Collaborative Wireless Freeview Video Streaming With Network Coding