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Wyner-Ziv video coding has become one of the hottest research topics in the video coding community due to the conceptual, theoretical and functional novelties it brings. Among the many practical architectures already available, feedback channel-based with channel coding, e.g. LDPC and turbo codes, solutions are rather popular. These solutions rely...
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... WZ video codec evaluated in this paper has been improved by the DISCOVER project team based on a first codec developed by the authors of this paper at Instituto Superior Técnico [4]. The DISCOVER WZ video codec architecture, illustrated in Figure 1, is based on the basic WZ video coding architecture proposed in [3], and it is presented in detail in [5]. However, at this stage, the initial architecture has already evolved, e.g. ...
Citations
... In video surveillance application, the camera has a long period inactive, it is very important to exploit the dynamic GOP structure to reduce the temporal redundancy. Some adaptive GOP structure algorithms have been proposed such as [22][23] [24] [25]. In [23], the authors presented a method for content adaptive GOP size control based on the computation of the bitrate and PSNR, when the average PSNR get the pre-determined maximum value, then insert the Key frame. ...
Video compression takes a very important part in multimedia communication. New applications require constrained resources in terms of power, computational complexity, memory and robustness. Distributed video coding (DVC) provides a solution to achieve such constraints. However, DVC has a low coding efficiency, the overall performance is lower than the H.264/AVC [1] codec. In low-motion scenes such as video conference or video surveillance, we can reduce the storage and transmission cost by using the long term background characteristics. In this paper, we propose a new DVC based on the background modeling of the scenes. We further analyze and design the corresponding optimized structure. We test different low motion video surveillance sequences, and show that the proposed block-based coding paradigm has a better performance compared with current DVC system. Experimental results show that the proposed background modeling method and coding scheme can save more than 14% bitrate and the overall rate-distortion (R-D) performance is increased 1.22 dB in average vs. Low-complexity DVC (LC-DVC) [2]. Our proposed codec architecture can support real time processing @15fps.
... Since low encoding complexity is the prime motivation for DVC, an evaluation of the complexity characteristics of the proposed feedback-channel-free architecture is unavoidable. To this end, the methodology used in [13,42] is adhered to; that is, the encoding and decoding complexity are evaluated using execution time measurements under regulated conditions b . ...
To provide low-complexity encoding for video in unidirectional or offline compression scenarios, this paper proposes an efficient feedback-channel-free distributed video coding architecture featuring a novel encoder-driven rate control scheme in tandem with a designated mode selection process. To this end, the encoder features a novel low-complexity motion estimation technique to approximate the side-information (SI) available at the decoder. Then, a SI-dependent correlation channel estimation between the approximated SI and the original frames is used to derive the theoretically required rate for successful Slepian-Wolf (SW) decoding. Based on the evaluation of the expected trade-off between the estimated required coding rate and the estimated distortion outcome, a novel encoder-side mode decision module assigns a different coding mode to distinct portions of the coded frames. In this context, skip, intra and SW coding modes are supported. To reduce the effect of underestimation, the final SW rate is adjusted upwards using a novel rate formula. Additionally, a successive SI refinement technique is exploited at the decoder to decrease the number of SW decoding failures. Experimental results illustrate the benefit of the different coding options and show similar or superior compression performance with respect to the feedback-based DISCOVER benchmark system. Finally, the low-complexity encoding characteristics of the proposed system are confirmed, as well as the beneficial impact of the proposed scheme on the decoding complexity.
... DVC has been utilized to error resilient digital video broadcasting of MPEG-2 video bit-stream [8]. The encoding complexity of DVC was evaluated in [9] and [10]. An novel scheme for scalable distributed video coding is introduced in [11], and has been proven to outperform non-scalable-DVC. ...
Distributed Video Coding (DVC) techniques utilize source statistics and dependencies among video frames in either spatial or time domain to compress the video and improve the error resilience. DVC promises great potentials for wireless video applications due to its advantages of using simple encoders. However, transmitting large size video stream consumes much network resource and still remains a challenging problem in terms of the resource efficiency. Recently, Cognitive Radio (CR) networks have been investigated to improve the bandwidth utilization through efficient channel allocations. Joint design of DVC and resource allocation in CR networks can provide a better solution to improve both resource efficiency and Quality of Service (QoS) performance of video transmissions. In this paper, we propose an efficient joint design scheme in which the interdependencies between cognitive radio resource management and the application-level characteristics of video traffic are jointly considered. Our studies show that the proposed scheme can significantly improve video transmission performance over CR networks.
... In general, the encoding complexity of a Wyner-Ziv video codec is dominated by H.264/AVC intra frame coding. Essentially, the complexity associated to WynerZiv encoding is negligible in relation to key frames' encoding complexity[27]. Hence, the lower the number of key frames in the encoded video sequence, i.e., the longer the GOP, the higher the gain in complexity offered by DVC with respect to H.264/AVC intra frame coding. Execution time measurements under controlled conditions, as defined by the VISNET I project[9],[27], have shown that the proposed codec brings an average encoding time reduction of approximately 30%, 50%, 60%, 65% for a GOP of size 2, 4, 8, and 16, respectively, compared to H.264/AVC Intra. ...
Recent advances in wireless visual sensor technology, have been calling for innovative architectures realizing efficient video coding under stringent processing and energy restrictions. Driven by profound findings in network information theory, Wyner-Ziv video coding constitutes a suitable paradigm for video sensor networks. This work presents a novel hash-driven Wyner-Ziv video coding architecture for visual sensors, which coarsely encodes a low resolution version of each Wyner-Ziv frame to facilitate accurate motion-compensated prediction at the decoder. The proposed method for side-information generation comprises hash-based multi-hypothesis pixel-based prediction. Once critical Wyner-Ziv information is decoded, the derived dense motion field is further enhanced. Experimental validation illustrates that the proposed hash-driven codec achieves significant compression gains with respect to state-of-the-art Wyner-Ziv video coding, even under demanding conditions.
... The results provided in Figure 5.8 confirm that the average compression performance of the WZ frames decreases as the GOP size increases, as expected. For more information about the impact of the GOP size on the compression performance of the DISCOVER system, the reader is referred to the literature [58]. ...
... Practical systems for DVC19 rate-compatible LDPC Accumulate (LDPCA) codes[57]. These codes perform slightly better than turbo codes[58].Other improvements include a coarse estimation of the WZ rate for reducing the number of requests through the feedback channel (similar to[59]), optimal centroid reconstruction of the decoded coefficients[60], and the use of a cyclic redundancy check (CRC) as an LDPCA stopping criterion. Similar or alternative techniques are discussed in this dissertation, and details will be provided where applicable. ...
... Algorithms for SI generation presented in the literature are based almost exclusively on block-based motion estimation and linear compensation techniques [7, 8]. These approaches are adopted from conventional residual-based video coding schemes, where the encoder reduces the amount of information by expressing the motion of many pixels by fewer motion vectors. ...
... The final SI distinguishes itself with very plausible image content, clear and sharp edges, without blurry and blocky discontinuation as known from block-based algorithms. In comparison to the often used BiMESS algorithm proposed in [8], it gains up to 2-4 dB in PSNR. ...
... Usually, transform domain WZ coding is employed to take an advantage of spatial redundancy as trade-off between additional encoder complexity and overall coding performance [8] . This techniques lead to some very annoying coding artifacts , as known from conventional DCT or Wavelet coding. ...
Distributed Video Coding (DVC) is a recent paradigm that offers emerging capabilities in contradiction to the established conventional video coding techniques. Based on the Slepian-Wolf (SW) and Wyner-Ziv (WZ) theorems, a DVC system has an outstanding low encoding complexity, by shifting the computational complex process of correlation exploration to the decoder. The fundamental DVC architecture is organized to reach a competitive Rate-Distortion (RD) performance in terms of PSNR, despite its low correlation with the human visual system (HSV). In contrast, this paper addresses the problem by proposing three image processing tools for exploiting spatio-temporal correlations to reduce the perceptual distortion of WZ frames. The proposed WZ pixel domain framework offers a comparable RD-performance referring to H.264 AVC intra coding.
... Therefore, the decoder exploit the temporal correlation by motion estimation. The basic structure of a common distributed video coding system with low encoder complexity ([3], [4]) is shown in figure 1. The input video sequence is split up into two types of frames. ...
Distributed video coding (DVC) is an important topic for emerging applications, for example visual sensor networks and mobile
video streaming. However, the major handicap applying DVC for real world applications is still the mandatory feedback channel.
In previous approaches, the rate allocation algorithm was relying on feedback channel data. Commonly bit plane by bit plane
decoding is done in a turbo code-based Slepian-Wolf decoder. In this paper inter bit plane decoding replaces the conventional
method. The proposed inter bit plane decoding facilitates the rate control, whereas only the sum data rate has to be estimated/requested
but not the data rate for each bit plane. This is one step forward to distributed video coding systems free of feedback channels.
... Relative to conventional coding schemes that employ motion estimation at the encoder, DVC provides a framework that eliminates this high computational burden altogether as well as the corresponding memory to store reference frames. Encoding complexity was evaluated in[19,41]. Not surprisingly, it showed that DVC encoding complexity (DISCOVER codec based on the Stanford architecture) was indeed providing a substantial speed-up when compared to conventional H.264/AVC Intra and H.264/AVC No Motion in terms of software execution time. ...
... But in general, several iterations are required to converge to a solution. In[19,41], it is shown that the DVC decoder is several orders of magnitude more complex in term of software execution time compared to that of a conventional H.264/AVC Intraframe decoder and about 10–20 times more complex than an H.264/AVC Intraframe encoder. ...
This paper surveys recent trends and perspectives in distributed video coding. More specifically, the status and potential benefits of distributed video coding in terms of coding efficiency, complexity, error resilience, and scalability are reviewed. Multiview video and applications beyond coding are also considered. In addition, recent contributions in these areas, more thoroughly explored in the papers of the present special issue, are also described.
... For the purpose of this paper, a significant number of scenarios have been considered, avoiding the up front elimination of any interesting scenario. Naturally, some of 1 Although theoretically DVC may reach the same compression efficiency as predictive coding (under certain conditions), practical solutions are not yet mature enough to reach this level of compression efficiency; however, there are already interesting solutions if a compression efficiency–complexity trade-off is considered [2,17]. them will be more promising than others as it will be concluded at the end of this paper. ...
... In practice, the DVC advantages should correspond to potential DVC benefits that most of the times may only become effective if the drawbacks are removed or, at least, significantly reduced. This is clearly the case regarding the coding efficiency gap which has been reduced in recent years in many ways, e.g. by improving the side information creation, and the correlation noise modeling [2,17]. Although a DVC-based system may not need to provide precisely the same rate-distortion (RD) performance as standards based coding systems to be commercially deployed, it must for sure provide a good enough tradeoff between advantages and drawbacks regarding alternative solutions. ...
... However, for lower complexity encoding there are already interesting solutions, e.g. providing a RD performance better then H.264/AVC Intra or even H.264/AVC zero motion with lower complexity [2,17]. Since there is a growing interest in DVC research, it is also expected that the DVC RD performance will improve substantially, thus eliminating or at least significantly reducing this drawback. ...
Distributed Video Coding (DVC) is a new video coding paradigm based on two major Information Theory results: the Slepian–Wolf and Wyner–Ziv theorems. Recently, practical DVC solutions have been proposed with promising results; however, there is still a need to study in a more systematic way the set of application scenarios for which DVC may bring major advantages. This paper intends to contribute for the identification of the most DVC friendly application scenarios, highlighting the expected benefits and drawbacks for each studied scenario. This selection is based on a proposed methodology which involves the characterization and clustering of the applications according to their most relevant characteristics, and their matching with the main potential DVC benefits.
... Due to the relationship between Slepian-Wolf coding and channel coding (see Section 1), the Slepian-Wolf codec is usually constituted by an efficient channel codec. While the first WZ coding solutions using the architecture adopted in this paper have made use of turbo codes [1,10], it is also possible to use other channel coding solutions such as LDPC codes; for a comparison between turbo and LDPC codes in the context of this WZ video coding architecture, please see [17]. ...
Abstract Wyner–Ziv (WZ) video coding—a,particular case of distributed video coding,(DVC)—is a new,video coding,paradigm based on two major Information Theory results: the Slepian–Wolf and Wyner–Ziv theorems. In recent years, some practical WZ video coding solutions have been proposed,with promising,results. One of the most popular,WZ video coding architectures in the literature uses turbo codes based Slepian–Wolf coding and a feedback,channel to perform,rate control at the decoder. This WZ video coding architecture has been first proposed,by researchers at Stanford University and has been after adopted and improved by many research groups around the world. However, while there are many papers published with changes and improvements to this architecture, the precise and detailed evaluation of its performance, targeting its deep understanding for future advances, has not been made. Available performance results are mostly partial, under unclear and incompatible conditions, using vaguely defined and also sometimes architecturally unrealistic codec solutions. This paper targets the provision of a detailed, clear, and complete performance evaluation of an advanced transform domain,WZ video codec derived from,the Stanford turbo coding and feedback,channel,based architecture. Although the WZ video codec proposed for this evaluation is among the best available, the main purpose and novelty of this paper is the solid and comprehensive performance evaluation made which will provide a strong, and very much needed, performance reference for researchers in this WZ video coding field, as well as a solid way to steer future WZ video coding research. r,2008 Elsevier B.V. All rights reserved. Keywords: Distributed video coding; Wyner–Ziv video coding; Turbo coding; Performance,evaluation
