An improved LDPC decoding scheme with reverse bit order mode for distributed video codec

In traditional distributed video coding (DVC), considering the correlation between the adjacent bitplanes, the LDPC-based joint bitplane decoding algorithm prefers to exploiting the decoded more significant bitplanes as the prior knowledge to decode the other less significant bitplanes for the better system performance. However, the prior knowledge does not always work well, especially when the quality of the side information (SI) is not so well. Therefore, in this paper we propose a reverse bit order mode for those blocks with poor quality in the SI to improve the LDPC decoding performance. For the pixels in these blocks, their corresponding binary representations will adopt reverse bit order to calculate the likelihood-ratio (LLR) values for LDPC iterative decoding. The experimental results show that compared with the joint bitplane decoding algorithm in [5], the PSNR gain for our proposed decoding scheme can reach up to 2.4 db.