High Definition Video Transmission over Wlans with Time-Scale and R-D Optimized Rate Adaptation

In this paper, we propose a transrating based video rate adaptation technique for compressed high-definition video transmission over wireless local area networks. Our application layer technique targets to prevent the quality impairments caused by inconsistent wireless bandwidth. The transrater at the server adjusts the transmission rate for each video frame, based on bandwidth measurements, to sustain the playout buffer fullness. Client periodically sends feedbacks after probing the available bandwidth using the video packet dispersions. The superiority of the proposed technique over the existing ones comes from its ability to select various time scales for rate adjustments. This feature avoids unnecessary rate reductions. Furthermore, transrating distortion is minimized by encoding type dependent rate allocation among the frames that will be transmitted in the projected time scale. Experimental results show that the proposed technique significantly reduces video glitches. Up to 2.43 dB average PSNR improvement is achieved compared to a delay-constraint unaware rate adaptation method, which also utilizes bandwidth measurements.