FlexCast: Graceful Wireless Video Streaming

Abstract

Video streaming performance on wireless networks is choppy. The culprit is the unpredictable wireless medium, whose fluctuations results in fluctuating throughput and bit errors. Current video codecs are not equipped to handle such variations since they exhibit an all or nothing behavior. If the channel is strong and above a threshold, the video stream gets decoded perfectly. If not, typically nothing gets decoded. Thus, there is no graceful degradation with wireless conditions. In this paper, we present a new technique FlexCast, that delivers a video reconstruction whose quality automatically varies with the channel conditions. The key idea is a novel joint-source channel code, that allows the sender to continuously transmit video bits, and the receiver to decode a video quality corresponding to the number of bits it receives and the instantaneous wireless channel quality. We show via experimental evaluation that name performs almost as well as the optimal scheme, and outperforms the state of the art graceful video delivery systems by nearly 6dB PSNR.