Distributed video coding with block mode decision to reduce temporal flickering

Abstract

The common distributed video coding (DVC) systems treat input video frames group by group. In each group of pictures (GOP), usually the first frame, called key frame, is intra-coded and the others are Wyner-Ziv (WZ)-coded. This GOP coding structure presents a fixed and inefficient coding mode switch (key or WZ) at group boundaries, thus preventing a DVC system from adapting the rate-distortion (R-D) performance to varying video content. In this work, a structure of temporal group of blocks (TGOB) with dynamic coding mode (key/WZ) decision is presented. This dynamic TGOB coding architecture determines each image block to be a key block or a WZ block based on spatiotemporal image analysis, resulting in a mode switch of fine granularity in both the spatial and temporal domains. As a consequence, not only the overall coding efficiency is improved, but also the temporal flickering artifacts for the reconstructed video are reduced substantially. Experimental results show that our proposed DVC scheme with block mode decision achieves up to 2.85 dB of quality gain and also up to 51% of temporal flickering reduction, compared to the well-known DISCOVER system.

Adaptive mode decision with residual motion compensation for distributed video coding

“…Moreover, the residual MC generated an additional residue to take advantage of correlation between the previously decoded and current noise residues. Experimental results amd with residual motion compensation for dvc 9 show that the coding efficiency of the proposed AMDMotion scheme can robustly improve the RD performance of TDWZ DVC without changing the encoder. For a GOP size of 2 the average bitrate saving of the AMDMotion codec is 35.5 and 9.26 (or equivalently the average improvement in PSNR is 1.2 and 0.5 dB) on WZ frames and all frames compared with the DISCOVER codec.…”

Adaptive mode decision with residual motion compensation for distributed video coding

“…Thereafter, X MC 2n is estimated by compensating X 2n−2ω (8) for the selected motion v (9). Let R 2n denote the current residue at time 2n, generated by OBMC, and let R MC 2n denote the motion compensated residue, where R 2n and R MC 2n are equivalent to R 0 and R 1 (Section II, Fig.…”

“…In [8], new techniques were proposed for intra and Wyner-Ziv (WZ) rate estimation, which drive a block-based encoder-side mode decision module deciding whether or not intra-coded information needs to be sent to the decoder in addition to the WZ bits. The work in [9] proposed to decide between WZ and intra blocks based on spatiotemporal features, including the temporal difference and spatial pixel variance. This reduces temporal flickering significantly, according to the authors.…”

A simple encoder scheme for distributed residual video coding

“…Encoder Block Mode Decision (EBMD) is a useful method for improving the coding efficiency and many literatures [9,11,13,17,22,24,32] have focused on this method.…”

“…Authors in [22] presented a structure of Temporal Group of Blocks (TGOB) at the encoder, which assesses the spatial-temporal properties of each image block to determine suitable modes dynamically. Experimental results show that achieved RD gains depend on video content.…”