UMSM: A Traffic Reduction Method on Multi-View Video Streaming for Multiple Users

Multi-view video consists of multiple video sequences captured simultaneously by multiple closely spaced cameras and enables users to freely change their viewpoints by playing different video sequences. Therefore, the transmission bitrate of multi-view video requires more bandwidth than conventional multimedia. In order to reduce the bandwidth requirement, User Dependent Multi-view Video Transmission (UDMVT), which is based on Multi-view Video Coding (MVC), has been proposed for single users. In UDMVT, the same frames are encoded into different versions for each user, which increases the transmission bitrate for multiple users because of the redundant transmission of overlapping frames. In order to address this problem, we proposed User dependent Multi-view video Streaming for Multi-users (UMSM). UMSM possesses two characteristics: overlapping frames required by multiple users are transmitted only once by multicast while un-overlapping frames required by each user are transmitted by unicast and offset of video requests between multiple users is aligned so as to maximize the area of overlapping frames. UMSM achieves a low transmission bitrate of multi-view video for multiple users by means of combining these characteristics. To investigate the effect of user´s view switching on traffic reduction, we design three types of view-switching models, namely, scanning model, random model, and watching model. Simulation results obtained using benchmark test sequences provided by MERL reveal that UMSM decreases the transmission bitrate by 80.6% on average for five users, as compared to MVC, when users gaze a viewpoint for a while after switching views in order to search an attractive viewpoint.