Robust Video Coding for Packet Networks with Feedback

Robustness to packet loss is a critical requirement for video communication over packet switched networks. Intra-coding is an important tool to mitigate the effects of packet loss by limiting error propagation. This work proposes an algorithm for optimal intra/inter coding mode selection, while utilizing the feedback channel that carries acknowledgement information about received packets. The overall distortion in frame reconstruction at the decoder due to quantization, error concealment (after packet loss) and error propagation is estimated at pixel-level precision, and is dynamically refined based on the feedback information. The estimate is then integrated into a rate-distortion (RD) framework for optimal selection of coding mode for each macroblock. Simulation results demonstrate that precise distortion estimation enables the coder to achieve substantial and consistent gains in PSNR over known state-of-the-art feedback-based mode selection methods.