# A Novel Consistent Quality Driven for JEM Based Distributed Video Coding
## 1 Introduction  
Video coding technologies have been playing an important role in the context of audiovisual services, such as digital TV, mobile video, and internet streaming, to cope with the high compression requirements. Most of the available video coding standards, notably the ITU-T H.26x and ISO/IEC MPEG-x standards [1], adopted the so-called predictive video coding paradigm, where the temporal and spatial correlations are exploited at the encoder by using motion estimation/motion compensation and spatial transforms, respectively. As a result, these coding standards typically lead to rather complex encoders and a much simpler decoder. However, a very low complexity at the encoder becomes a more essential feature for video coding schemes with the explosion of emerging applications, such as low-power video surveillance,wireless visual sensor networks, and wireless PC/Mobile cameras [2]. At the light of an information theory resulted in the 1970s: The Slepian-Wolf theorem [3] distributed video coding (DVC) can be considered as a new and efficient paradigm to address the requirement of these emerging applications. In [3], [PERSON] et al. proved that two correlated sources could be independently encoded without any loss in the coding efficiency if they are jointly decoded by exploiting source statistics. In 1976, Wyner-Ziv theorem further proved a similar source coding method while using side information for lossy compression [4]. Video coding schemes in DVC can effectively exploit the temporal correlation at the decoder rather than at the encoder without rate-distortion performance penalty based on Slepian-Wolf and Wyner-Ziv theorems; this allows moving motion estimation and its complexity to the decoder, thus achieving simpler encoders. Generally, there are two main practical approaches to the DVC design: the DVC Stanford [5] and the DVC Berkeley [6] solutions. As of today, the most popular DVC codec design in the literature is the DVC Stanford architecture, which works at the frame level and it is characterized by a feedback channel based decoder rate control [7]. In the DVC Stanford architecture, the input video is separated into two parts: the key and WZ frames. The key frames are encoded while using the conventional Intra coding and the WZ frames are coded while using the WZ coding scheme. In the case of WZ coding, the outputs of the DVC encoder are parity bits; however, only a part of these parity bits are sent to the decoder to improve the coding efficiency of the DVC codec. Several approaches have been introduced to improve the performance of the DVC Stanford architecture. In [8], [PERSON] et al. proposed a realistic WZ coding approach by estimating the correlation noise model (CNM) at the decoder for efficient pixel and transform domain WZ coding. In [9], the authors et al. presented a novel H.265/HEVC based DVC, in which the low complexity HEVC Intra profile is employed to encode the key frames. Among the different DVC codecs following the Stanford architecture, DISCOVER DVC [10], as developed by the European project, is one of the best DVC codec reported in the literature. A thorough performance benchmark of this codec is available in [11], where the coding efficiency of the DISCOVER DVC codec is compared to two variants of H.264/AVC with low encoding complexity: H.264/AVC Intra and H.264/AVC No motion [12]. However, we have not compared our approach to a recent video coding that is based on second generation wavelets [13]--so it is not DCT-based--even if it is very efficient in low bit rates, but it may compromise our goal of developing a coder for low complexity constrained video applications. The problem of providing consistent video quality for the DVC decoded frames is still limited so far, although many approaches have been introduced in the literature to effectively improve the performance of DVC codecs. In [14], [PERSON] et al.