Research On Feedback-Free Distributed Video Coding Techniques

The traditional video coding solutions, represented by the ISO/IEC MPEG-x and ITU-T H.26 x standards, with high compression efficiency have been widespread concerned. However, they rely on a highly complex encoder to exploit the temporal and spatial redundancy. This may be not optimal for some practical scenarios with limited transmission delay and energy, such as wireless video sensor networks and low-power surveillance.Hence, the distributed video coding(DVC), based on Slepian-Wolf and Wyner-Ziv theorems, was proposed to shift the computation and storage burdens to the decoder. It encodes the video frames independently and decodes them jointly, which turns out to be an optimal scheme in scarce resource scenarios.Available DVC codecs are mostly based on decoder rate control(DRC) scheme where the parity bits for decoding can be achieved over a feedback channel. However, the frequent requests through feedback cause transmission delay. The feedback-free DVC, relying on encoder rate control(ERC) in literatures, has overcome these shortcomings. But it is usually carried out on the coding unit of bit-plane, which requires high precision of bit rate estimation and high quality of side information(SI) approximation at the encoder. In this paper, we propose to improve the coding efficiency under low encoder complexity. The innovation includes three parts: 1) an adaptive coding model selection(ACMS) algorithm, utilizing both temporal and spatial correlation, is proposed to lower the parity bits rate and the complexity in generating SI frame; 2) a bit-plane rearrangement method is used to make the coding rate on each bit-plane homogeneous. As a result, rate estimation needs to be performed only once for all bit-planes within one frame; 3) a frame-level parity bits estimation scheme is presented to enhance the efficiency of rate estimation on the basis of a lookup table. Numerical results indicate a remarkable improvement of rate distortion(RD) performance relative to the ERC framework our codec based on under low-complexity.