DVC based video codecs proposed in the literature generally include a reverse (feedback) channel between the encoder and the decoder. This channel is used to communicate the dynamic parity bit request messages from the decoder to the encoder resulting in an optimum dynamic variable rate control implementation. However it is observed that this dynamic feedback mechanism is a practical hindrance in a number of practical consumer electronics applications. In this paper we proposed a novel transform domain Unidirectional Distributed Video Codec (UDVC) without a feedback channel. First, all Wyner-Ziv frames are divided into rectangular macroblocks. A simple metric is used for each block to represent the correlations between the corresponding blocks in the adjacent key frame and the Wyner-Ziv frame. Based on the value of this metric, parity is allocated dynamically for each block. These parities are either stored for offline processing or transmitted to the DVC decoder for on line processing. Simulation results show that the proposed codec outperforms the existing UDVC solutions by a significant margin.

Distributed Video Coding (DVC) is an emerging video coding paradigm that is characterized by a flexible architecture for designing very low cost video encoders. This feature could be very effectively utilized in a number of potential many-to-one type video coding applications. However, the compression efficiency of the latest DVC implementations still falls behind the state-of-the-art in conventional video coding technologies, namely H.264/AVC. In this paper, a novel non-linear quantization algorithm is proposed for DVC in order to improve the rate-distortion (RD) performance. The proposed solution is expected to exploit the dominant contribution to the picture quality from the relatively small coefficients when the high concentration of the coefficients near zero as evident when the residual input video signal for the Wyner-Ziv frames is considered in the transform domain. The performance of the proposed solution incorporating the non-linear quantizer is compared with the performance of an existing transform domain DVC solution that uses a linear quantizer. The simulation results show a consistently improved RD performance at all bitrates when different test video sequences with varying motion levels are considered.