Fine-grained rate shaping for video streaming over wireless networks

Streaming of precoded video, which is both source and channel coded, over wireless networks faces challenges of time-varying packet loss rate and fluctuating bandwidth. Rate shaping has been proposed (Chen, T.P.-C. and Chen, T., ICASSP, 2002) to "shape" the precoded video to adapt to the real-time bandwidth requirement and the packet loss rate. We now propose a novel "fine-grained rate shaping" (FGRS) scheme to allow for bandwidth adaptation over a wide range of bandwidth and packet loss rate. The video is precoded with fine granularity scalability (FGS) followed by forward error correction (FEC) coding with erasure codes. Utilizing the fine granularity property of FGS and FEC, FGRS selectively drops part of the precoded video and still yields a decodable bitstream at the decoder. A new two-stage rate-distortion (R-D) optimization, with model-based hyper-plane and hill-climbing based refinement, is proposed to select which part of the precoded video to drop. Promising results for FGRS are shown.