Channel adaptive video stream switching for broadband wireless links

Abstract

This paper exploits H.264/Advanced Video Codec smooth stream switching to achieve robust video delivery across an IEEE 802.16 (WiMAX) broadband wireless link. As the wireless channel conditions vary over time, dynamic selection of bitrate and corresponding video quality will reduce the risk of harmful packet loss. Choice of stream-switching with Secondary SP-frames or SI-frames is investigated relative to the selection of quantization parameter (QP) values. To control the switching points at the WiMAX server, a feedback mechanism that monitors packet loss is applied. An adaptive ARQ scheme is alternatively exploited to protect switching frames against packet loss. The broadband wireless streaming system gives more protection to higher quality video, reduces delay and packet loss, and improves received video quality. In particular, for the QP values selected, results show that increased quality primary switching frames with SIframes bring a significant gain in video quality over the other switching schemes with secondary SP-frames, which in turn show an improvement over 'no switching' for a typical WiMAX channel with burst errors. Link delay is also reduced.