VSHAPER: an efficient method of serving video streams shaped for diverse wireless communication conditions

The transmission of video over wireless channels is a challenging problem, in part due to the rapid and wide variations in wireless channel bandwidth and error conditions. In this paper, we present a run-time method for assembling a video stream, VSHAPER, that shapes the video stream depending on the current wireless channel conditions. Previous methods for shaping video streams have either concentrated on bandwidth adaptation only, or have required the video stream to be compressed at run-time. VSHAPER assembles the output video stream from several pre-compressed videos, requiring minimal computational overhead at the video server. A modified rate-distortion optimization method for deciding how to shape the video stream is also used to minimize computational overhead. The output of VSHAPER is a video stream that can be read by any standard video decoder. Significant gains in the video quality of received video during varying wireless conditions are observed. In addition, a video server's capacity (number of video streams it can simultaneously serve) is increased significantly.