Research On Distributed Video Coding Based On Ldpc Codes

Distributed Video Coding (DVC) is a new paradigm for video compression. Compared with traditional video coding, DVC is a radical departure. When channel coding, e.g. Turbo code is applied to, DVC has the characteristic of simple encoding, as well as good error-resilient performance. Thus, DVC is well-suited for the wireless video surveillance applications, where computing power, storage capacity and power consumption are all limited. Since 2002 some scholars have been doing research on DVC, which now has become a fascinating research topic.This paper firstly implements the DVC system based on LDPC codes. Then the paper focuses on the construction rate adaptive codes and side information estimation in DVC. The main work and achievements are as follows:1. LDPC codes and its application are introduced in briefly. Then the BP decoding algorithm for LDPC codes is derived in details. And the Pixel-Domain DVC systems based on LDPC codes are implemented by C++ language and are compared with DVC systems based on Turbo codes.2. A new rate-adaptive LDPC coding algorithm is proposed. Firstly, a high compression ratio code is constructed based on Progressive Edge-Growth (PEG) algorithm. Then low compression ratio codes are got by row splitting algorithm. The rate can be well adjusted by merging and splitting the parity-check matrix rows. And three restriction conditions for merging check nodes are proposed in order to get good performance codes. Based on the rate adaptive LDPC codes, a rate adaptive DVC algorithm is proposed, which can get better RD performance about 0.1~0.7dB compared to DVC algorithm based on the popular Turbo codes, when the correlation between the original and side information is medium or high.3. The side information estimation methods in DVC systems are discussed in details. Based on bilateral motion estimation, motion vector filtering and weighted multi-frame estimation, a new algorithm of weighting 2 reconstructed frames and 2 adjacent key frames is proposed. Then, the side information estimation in case of multi-Wyner-Ziv-frame is analyzed by the proposed algorithm. And the above estimation methods are adopted in the rate adaptive DVC systems based on LDPC codes.