In Wyner-Ziv video coding architectures, the available bit budget to each GOP is shared between key frames and Wyner-Ziv frames. In this work, we first propose a model to express the relationship between quantization step size of key and WZ frames based on their motion activity. Then we apply this model to propose an adaptive algorithm adjusting the quantization step size of key and WZ frames to achieve and maintain a target bit rate. We evaluate the rate distortion performance of the proposed method and compare to a common method in the literature.

We improve the overall rate-distortion performance of distributed video coding by efficient techniques of correlation noise estimation and key frame encoding. In existing transform-domain Wyner-Ziv video coding methods, blocks within a frame are treated uniformly to estimate the correlation noise even though the success of generating side information is different for each block. We propose a method to estimate the correlation noise by differentiating blocks within a frame based on the accuracy of the side information. Simulation results show up to 2 dB improvement over conventional methods without increasing encoder complexity. Also, in traditional Wyner-Ziv video coding, the intercorrelation of key frames is not exploited since they are simply intracoded. In this paper, we propose a frequency band coding mode selection for key frames to exploit similarities between adjacent key frames at the decoder. Simulation results show significant improvement especially for low-motion and high frame rate sequences. Furthermore, the advantage of applying both schemes in a hierarchical order is investigated. This method achieves additional improvement.

In most Wyner-Ziv video coding approaches, the temporal correlation of key frames is not exploited since they are simply intra encoded and decoded. In this paper, using the previously decoded key frame as the side information for the key frame to be decoded, we propose new methods of coding key frames in order to improve the rate distortion performance. These schemes which are based on switching between intra mode and Wyner-Ziv mode for a given block or a given frequency band attempt to make use of both spatial and temporal correlation of key frames while satisfying the low complexity encoding requirement of distributed video coding (DVC). Simulation results show that using the proposed methods, one can achieve up to 5 dB improvement over conventional intra coding for relatively low motion sequences and up to 1.3 dB improvement for relatively high motion sequences.

Distributed source coding strongly depends on the knowledge of statistical dependency between source and side information. In transform domain Wyner-Ziv video coding (TDWZ) this statistical dependency (also known as correlation noise) has been usually modeled by a unique Laplacian distribution for each frequency band. In this paper, we propose a method to define different classes of correlation noise for each frequency band based on the accuracy of the side information. With this approach the correlation between source and side information is estimated separately for each frequency band of each class. Therefore, the decoder can discriminate blocks in order to estimate the correlation noise of their frequency bands. Simulation results show that applying the proposed method improves rate-distortion performance.

In most Wyner-Ziv video coding approaches, the temporal correlation of key frames is not exploited, since they are simply intra encoded and decoded. In previous work, by using the previously decoded key frames as the side information, we proposed to divide the frequency bands of each block into two classes. Wyner-Ziv coding was used for the low frequency bands of each block, while high frequency bands were intra coded. In this paper, we improve this approach with an efficient coding mode selection technique. Frequency bands are grouped as low and high bands and an appropriate method of coding is selected for them based on the correlation characteristics of each frame with the past. This method does not add complexity to the encoder. Simulation results show that using the proposed method, one can achieve up to 4 dB improvement over prior work.