Research On Distributed Video Coding With Limited Feedback Requests

Distributed video coding(DVC) has been widely applied in the emerging wireless video transmission field because of its simple encoder complexity, high compression efficiency and robustness. The DVC systems available are structurally divided into encoder rate control(ERC) systems and decoder rate control(DRC) systems. DRC systems guarantee that each frame is successfully decoded with a minimum parity bits rate through the feedback channel. However, frequent feedback requests increase processing complexity and delay of video sequence. ERC systems have less processing complexity and time delay. But it can hardly achieve high compression efficiency with low encoder complexity. To overcome the shortcomings aforementioned, this paper proposes a DVC system with limited feedback requests. A new feedback control algorithm is used to restrict the number of feedback requests. The proposed algorithm obtains the final rate with two steps, initial rate allocation and additional rate allocation. The number of feedback requests is decreased by purposefully requesting for the additional rate through feedback channel. To achieve better rate distortion(RD), the proposed DVC architecture also performs frame classification, side information refinement and correlation noise model refinement. Frame classification module makes the judgment whether the current frame worth coding according to the motion intensity, which reduces the complexity of DVC system. Side information and correlation noise model refinement are performed based on correctly decoded bit-planes, which contributes to decreasing the error rate of the decoded frame. Experimental results show that the new feedback control algorithm significantly decreases the number of feedback requests, the maximum number is 3. A good rate RD performance is also achieved with only one request. The proposed architecture has a better RD performance than encoder rate control systems, and it also achieves a similar performance to DRC systems without feedback constraints in literature.