Customizing short-length LT codes with evolution strategies for video streaming protection

摘要

Designing short-length Luby Transform (SLLT) codes to best protect video streaming and multicasting over lossy communication remains largely an empirical exercise. In this paper, we present a systematic approach to customize the decoding performance of these codes so that the protected video bitstreams may have the best playback quality over a wide range of channel loss rates. Our approach begins with the proposal of a new SLLT decoding performance model based on three parameters: decoding overhead, symbol decoding failure rate and tail probability of symbol decoding failure rate. We then formulate the design of SLLT codes as a multi-objective optimization problem, specify the design objectives in terms of goal program, and search for the most suitable codes using an augmented weighted Tchebycheff method implemented with the Covariance Matrix Adaptation Evolution Strategy (CMA-ES). Two design examples are provided to illustrate the effectiveness of our approach: (1) an SLLT postcode of a short-length raptor code that provides erasure protection to H.264 AVC bitstreams, and (2) an SLLT post-code of a rateless UEP code that supports graceful degradation of H.264 SVC playback quality. Empirical results demonstrate that the proposed method is capable of producing SLLT codes with customized decoding performance, whereas, the customized codes enable the playback pictures to attain significantly higher PSNR values at different stages of the decoding process than the pictures recovered under the protection of conventionally optimized codes.