International Journal of Digital Multimedia Broadcasting https://www.hindawi.com The latest articles from Hindawi © 2017 , Hindawi Limited . All rights reserved. Low-Light Image Enhancement Based on Guided Image Filtering in Gradient Domain Thu, 28 Sep 2017 00:00:00 +0000 http://www.hindawi.com/journals/ijdmb/2017/9029315/ We propose a novel approach for low-light image enhancement. Based on illumination-reflection model, the guided image filter is employed to extract the illumination component of the underlying image. Afterwards, we obtain the reflection component and enhance it by nonlinear functions, sigmoid and gamma, respectively. We use the first-order edge-aware constraint in the gradient domain to achieve good edge preserving features of enhanced images and to eliminate halo artefact effectively. Moreover, the resulting images have high contrast and ample details due to the enhanced illumination and reflection component. We evaluate our method by operating on a large amount of low-light images, with comparison with other popular methods. The experimental results show that our approach outperforms the others in terms of visual perception and objective evaluation. Xiankun Sun, Huijie Liu, Shiqian Wu, Zhijun Fang, Chengfan Li, and Jingyuan Yin Copyright © 2017 Xiankun Sun et al. All rights reserved. Adaptive Geometry Images for Remeshing Wed, 02 Aug 2017 00:00:00 +0000 http://www.hindawi.com/journals/ijdmb/2017/2724184/ Geometry images are a kind of completely regular remeshing methods for mesh representation. Traditional geometry images have difficulties in achieving optimal reconstruction errors and preserving manually selected geometric details, due to the limitations of parametrization methods. To solve two issues, we propose two adaptive geometry images for remeshing triangular meshes. The first scheme produces geometry images with the minimum Hausdorff error by finding the optimization direction for sampling points based on the Hausdorff distance between the original mesh and the reconstructed mesh. The second scheme produces geometry images with higher reconstruction precision over the manually selected region-of-interest of the input mesh, by increasing the number of sampling points over the region-of-interest. Experimental results show that both schemes give promising results compared with traditional parametrization-based geometry images. Lina Shi, Dehui Kong, Shaofan Wang, and Baocai Yin Copyright © 2017 Lina Shi et al. All rights reserved. Visual Three-Dimensional Reconstruction of Aortic Dissection Based on Medical CT Images Wed, 19 Jul 2017 07:12:01 +0000 http://www.hindawi.com/journals/ijdmb/2017/3163759/ With the rapid development of CT technology, especially the higher resolution of CT machine and a sharp increase in the amount of slices, to extract and three-dimensionally display aortic dissection from the huge medical image data became a challenging task. In this paper, active shape model combined with spatial continuity was adopted to realize automatic reconstruction of aortic dissection. First, we marked aortic feature points from big data sample library and registered training samples to build a statistical model. Meanwhile, gray vectors were sampled by utilizing square matrix, which set the landmarks as the center. Posture parameters of the initial shape were automatically adjusted by the method of spatial continuity between CT sequences. The contrast experiment proved that the proposed algorithm could realize accurate aorta segmentation without selecting the interested region, and it had higher accuracy than GVF snake algorithm (93.29% versus 87.54% on aortic arch, 94.30% versus 89.25% on descending aorta). Aortic dissection membrane was extracted via Hessian matrix and Bayesian theory. Finally, the three-dimensional visualization of the aortic dissection was completed by volume rendering based on the ray casting method to assist the doctors in clinical diagnosis, which contributed to improving the success rate of the operations. Xiaojie Duan, Dandan Chen, Jianming Wang, Meichen Shi, Qingliang Chen, He Zhao, Ruixue Zuo, Xiuyan Li, and Qi Wang Copyright © 2017 Xiaojie Duan et al. All rights reserved. Research of Simulation in Character Animation Based on Physics Engine Wed, 12 Jul 2017 00:00:00 +0000 http://www.hindawi.com/journals/ijdmb/2017/4815932/ Computer 3D character animation essentially is a product, which is combined with computer graphics and robotics, physics, mathematics, and the arts. It is based on computer hardware and graphics algorithms and related sciences rapidly developed new technologies. At present, the mainstream character animation technology is based on the artificial production of key technologies and capture frames based on the motion capture device technology. 3D character animation is widely used not only in the production of film, animation, and other commercial areas but also in virtual reality, computer-aided education, flight simulation, engineering simulation, military simulation, and other fields. In this paper, we try to study physics based character animation to solve these problems such as poor real-time interaction that appears in the character, low utilization rate, and complex production. The paper deeply studied the kinematics, dynamics technology, and production technology based on the motion data. At the same time, it analyzed ODE, PhysX, Bullet, and other variety of mainstream physics engines and studied OBB hierarchy bounding box tree, AABB hierarchical tree, and other collision detection algorithms. Finally, character animation based on ODE is implemented, which is simulation of the motion and collision process of a tricycle. Yang Yu, Jucheng Yang, Xiaofei Zan, Jiangang Huang, and Xiangbo Zhang Copyright © 2017 Yang Yu et al. All rights reserved. Prior Knowledge-Based Event Network for Chinese Text Sun, 04 Jun 2017 08:25:11 +0000 http://www.hindawi.com/journals/ijdmb/2017/8594863/ Text representation is a basic issue of text information processing and event plays an important role in text understanding; both attract the attention of scholars. The event network conceals lexical relations in events, and its edges express logical relations between events in document. However, the events and relations are extracted from event-annotated text, which makes it hard for large-scale text automatic processing. In the paper, with expanded CEC (Chinese Event Corpus) as data source, prior knowledge of manifestation rules of event and relation as the guide, we propose an event extraction method based on knowledge-based rule of event manifestation, to achieve automatic building and improve text processing performance of event network. Yunyu Shi, Jianfang Shan, Xiang Liu, and Yongxiang Xia Copyright © 2017 Yunyu Shi et al. All rights reserved. A Novel Preferential Diffusion Recommendation Algorithm Based on User’s Nearest Neighbors Thu, 04 May 2017 00:00:00 +0000 http://www.hindawi.com/journals/ijdmb/2017/1386461/ Recommender system is a very efficient way to deal with the problem of information overload for online users. In recent years, network based recommendation algorithms have demonstrated much better performance than the standard collaborative filtering methods. However, most of network based algorithms do not give a high enough weight to the influence of the target user’s nearest neighbors in the resource diffusion process, while a user or an object with high degree will obtain larger influence in the standard mass diffusion algorithm. In this paper, we propose a novel preferential diffusion recommendation algorithm considering the significance of the target user’s nearest neighbors and evaluate it in the three real-world data sets: MovieLens 100k, MovieLens 1M, and Epinions. Experiments results demonstrate that the novel preferential diffusion recommendation algorithm based on user’s nearest neighbors can significantly improve the recommendation accuracy and diversity. Fuguo Zhang, Yehuan Liu, and Qinqiao Xiong Copyright © 2017 Fuguo Zhang et al. All rights reserved. Rate-Distortion and Rate-Energy-Distortion Evaluations of Compressive-Sensing Video Coding Thu, 16 Mar 2017 06:20:12 +0000 http://www.hindawi.com/journals/ijdmb/2017/4589124/ Compressive-Sensing Video Coding (CSVC) is a new video coding framework based on compressive-sensing (CS) theory. This paper presents the evaluations on rate-distortion performance and rate-energy-distortion performance of CSVC by comparing it with the popular hybrid video coding standard H.264 and distributed video coding (DVC) system DISCOVER. Experimental results show that CSVC achieves a poor rate-distortion performance when compared with H.264 and DISCOVER, but its rate-energy-distortion performance has a distinct advantage; moreover, its energy consumption of coding is approximately invariant regardless of reconstruction quality. It can be concluded that, with a limited energy budget, CSVC outperforms H.264 and DISCOVER, but its rate-distortion performance still needs improvement. Bingyu Ji, Ran Li, and Changan Wu Copyright © 2017 Bingyu Ji et al. All rights reserved. Adaptive Image Compressive Sensing Using Texture Contrast Mon, 13 Mar 2017 00:00:00 +0000 http://www.hindawi.com/journals/ijdmb/2017/3902543/ The traditional image Compressive Sensing (CS) conducts block-wise sampling with the same sampling rate. However, some blocking artifacts often occur due to the varying block sparsity, leading to a low rate-distortion performance. To suppress these blocking artifacts, we propose to adaptively sample each block according to texture features in this paper. With the maximum gradient in 8-connected region of each pixel, we measure the texture variation of each pixel and then compute the texture contrast of each block. According to the distribution of texture contrast, we adaptively set the sampling rate of each block and finally build an image reconstruction model using these block texture contrasts. Experimental results show that our adaptive sampling scheme improves the rate-distortion performance of image CS compared with the existing adaptive schemes and the reconstructed images by our method achieve better visual quality. Fang Sun, Dongyue Xiao, Wei He, and Ran Li Copyright © 2017 Fang Sun et al. All rights reserved. A Novel Steganography Technique for SDTV-H.264/AVC Encoded Video Mon, 09 May 2016 12:58:09 +0000 http://www.hindawi.com/journals/ijdmb/2016/6950592/ Today, eavesdropping is becoming a common issue in the rapidly growing digital network and has foreseen the need for secret communication channels embedded in digital media. In this paper, a novel steganography technique designed for Standard Definition Digital Television (SDTV) H.264/AVC encoded video sequences is presented. The algorithm introduced here makes use of the compression properties of the Context Adaptive Variable Length Coding (CAVLC) entropy encoder to achieve a low complexity and real-time inserting method. The chosen scheme hides the private message directly in the H.264/AVC bit stream by modifying the AC frequency quantized residual luminance coefficients of intrapredicted I-frames. In order to avoid error propagation in adjacent blocks, an interlaced embedding strategy is applied. Likewise, the steganography technique proposed allows self-detection of the hidden message at the target destination. The code source was implemented by mixing MATLAB 2010 b and Java development environments. Finally, experimental results have been assessed through objective and subjective quality measures and reveal that less visible artifacts are produced with the technique proposed by reaching PSNR values above 40.0 dB and an embedding bit rate average per secret communication channel of 425 bits/sec. This exemplifies that steganography is affordable in digital television. Christian Di Laura, Diego Pajuelo, and Guillermo Kemper Copyright © 2016 Christian Di Laura et al. All rights reserved. Enhancing the Security of Customer Data in Cloud Environments Using a Novel Digital Fingerprinting Technique Wed, 04 May 2016 11:25:10 +0000 http://www.hindawi.com/journals/ijdmb/2016/8789397/ With the rapid rise of the Internet and electronics in people’s life, the data related to it has also undergone a mammoth increase in magnitude. The data which is stored in the cloud can be sensitive and at times needs a proper file storage system with a tough security algorithm. Whereas cloud is an open shareable elastic environment, it needs impenetrable and airtight security. This paper deals with furnishing a secure storage system for the above-mentioned purpose in the cloud. To become eligible to store data a user has to register with the cloud database. This prevents unauthorized access. The files stored in the cloud are encrypted with RSA algorithm and digital fingerprint for the same has been generated through MD5 message digest before storage. The RSA provides unreadability of data to anyone without the private key. MD5 makes it impossible for any changes on data to go unnoticed. After the application of RSA and MD5 before storage, the data becomes resistant to access or modifications by any third party and to intruders of cloud storage system. This application is tested in Amazon Elastic Compute Cloud Web Services. Nithya Chidambaram, Pethuru Raj, K. Thenmozhi, and Rengarajan Amirtharajan Copyright © 2016 Nithya Chidambaram et al. All rights reserved. Model Aspects of Open Access to Multimedia Broadcast Services in the Evolved Packet System Wed, 02 Mar 2016 12:56:46 +0000 http://www.hindawi.com/journals/ijdmb/2016/3154801/ Multimedia broadcast is the most efficient method to distribute identical content to multiple users in the Evolved Packet System (EPS). EPS enables efficient usage of network resources and provisioning of quality of service for every user. Third-party control allows applications in an enterprise domain to invoke network functions like multimedia broadcast. In this paper, an approach to modeling the behavior of Service Capability Server (SCS) for multimedia broadcast in EPS is presented. Third-party applications can access multimedia broadcasting capabilities by using Parlay X Web Service interfaces. The SCS for multimedia broadcast exposes Parlay X interfaces toward 3rd-party applications and control protocols toward the network. The SCS functional behavior has to be synchronized with the application view on message broadcast and the state of the network resources intended for the broadcast session. Models of multicast session, IP connectivity session, and bearers’ and charging session are proposed and formally described using the notation of Label Transition Systems. The concept of weak bisimilarity is used to prove that models expose equivalent behavior; that is, they are synchronized. Ivaylo Atanasov and Evelina Pencheva Copyright © 2016 Ivaylo Atanasov and Evelina Pencheva. All rights reserved. Adaptive Streaming of Scalable Videos over P2PTV Wed, 12 Aug 2015 07:10:46 +0000 http://www.hindawi.com/journals/ijdmb/2015/283097/ In this paper, we propose a new Scalable Video Coding (SVC) quality-adaptive peer-to-peer television (P2PTV) system executed at the peers and at the network. The quality adaptation mechanisms are developed as follows: on one hand, the Layer Level Initialization (LLI) is used for adapting the video quality with the static resources at the peers in order to avoid long startup times. On the other hand, the Layer Level Adjustment (LLA) is invoked periodically to adjust the SVC layer to the fluctuation of the network conditions with the aim of predicting the possible stalls before their occurrence. Our results demonstrate that our mechanisms allow quickly adapting the video quality to various system changes while providing best Quality of Experience (QoE) that matches current resources of the peer devices and instantaneous throughput available at the network state. Youssef Lahbabi, El Hassan Ibn Elhaj, and Ahmed Hammouch Copyright © 2015 Youssef Lahbabi et al. All rights reserved. On the Feasibility of Unlicensed Communications in the TV White Space: Field Measurements in the UHF Band Mon, 23 Feb 2015 08:50:13 +0000 http://www.hindawi.com/journals/ijdmb/2015/319387/ In practical unlicensed communications in TV band, radio devices have to identify, at first, the transmission opportunities, that is, the portion of the spectrum licensed for broadcasting services unoccupied in a certain region at certain time, that is, the so-called TV white space. In this paper the outcome of field measurements in the UHF TV band (470–860 MHz) conducted in EU is presented. To obtain empirical values for the parameters upon which unlicensed radio devices are able to distinguish in a real scenario between empty and occupied TV channels, signal power measurements have been performed in Italy, Spain, and Romania on rural, suburban, and urban sites, at different heights over the ground by using different analysis bandwidths. The aim of this work is to provide a set of practical parameters upon which harmless unlicensed communication in the UHF TV white space is feasible. The results have been analyzed with respect to the hidden node margin problem, spectrum sensing bandwidth, and occupancy threshold. M. Fadda, V. Popescu, M. Murroni, P. Angueira, and J. Morgade Copyright © 2015 M. Fadda et al. All rights reserved. Generalized Block-Diagonalization Schemes for MIMO Relay Broadcasting Systems Wed, 31 Dec 2014 00:10:07 +0000 http://www.hindawi.com/journals/ijdmb/2014/305846/ We propose two generalized block-diagonalization (BD) schemes for multiple-input multiple-output (MIMO) relay broadcasting systems with no channel state information (CSI) at base station. We first introduce a generalized zero forcing (ZF) scheme that reduces the complexity of the traditional BD scheme. Then the optimal power loading matrix for the proposed scheme is analyzed and the closed-form solution is derived. Furthermore, an enhanced scheme is proposed by employing the minimum-mean-squared-error (MMSE) criterion. Simulation results show that the proposed generalized MMSE scheme outperforms the other schemes and the optimal power loading scheme improves the sum-rate performance efficiently. Xianan Wang, Xiaoxiang Wang, Wenrong Gong, and Zijia Huang Copyright © 2014 Xianan Wang et al. All rights reserved. Decision Feedback Blind Equalizer with Tap-Leaky Whitening for Stable Structure-Criterion Switching Wed, 31 Dec 2014 00:10:04 +0000 http://www.hindawi.com/journals/ijdmb/2014/987039/ The research presented in this paper improves the structure-criterion switching performance of the blind decision feedback equalizer (DFE) which eliminates error propagation effects by optimizing both the structure and the cost criterion. To conquer the complexity of the 64-QAM (quadrature amplitude modulated) signal constellation, the stochastic entropy-gradient algorithm is additionally regularized by the coefficient leaky term to avoid a coefficients norm overgrowth of the received signal whitener. Effectively, the leak of coefficients is employed to ensure a stable structure-criterion switching of DFE between blind and decision-directed operation modes. The optimization of the resulting whitening algorithm is achieved by means of two free, leaky and entropic, parameters which act in opposition to each other. Both, the influence of the 64-QAM signal on the feedback filter behavior and the parametric optimization of the whitening algorithm are analyzed through simulations. Vladimir R. Krstić and Miroslav L. Dukić Copyright © 2014 Vladimir R. Krstić and Miroslav L. Dukić. All rights reserved. A New QIM-Based Watermarking Method Robust to Gain Attack Thu, 11 Sep 2014 09:59:35 +0000 http://www.hindawi.com/journals/ijdmb/2014/910808/ We propose a new watermarking method based on quantization index modulation. A concept of initial data loss is introduced in order to increase capacity of the watermarking channel under high intensity additive white Gaussian noise. According to the concept some samples in predefined positions are ignored even though this produces errors in the initial stage of watermark embedding. The proposed method also exploits a new form of distribution of quantized samples where samples that interpret “0” and “1” have differently shaped probability density functions. Compared to well-known watermarking schemes, this provides an increase of capacity under noise attack and introduces a distinctive feature. Two criteria are proposed that express the feature numerically. The criteria are utilized by a procedure for estimation of a gain factor after possible gain attack. Several state-of-the-art quantization-based watermarking methods were used for comparison on a set of natural grayscale images. The superiority of the proposed method has been confirmed for different types of popular attacks. Yevhen Zolotavkin and Martti Juhola Copyright © 2014 Yevhen Zolotavkin and Martti Juhola. All rights reserved. Efficient Time-Frequency Localization of a Signal Mon, 25 Aug 2014 08:51:00 +0000 http://www.hindawi.com/journals/ijdmb/2014/529852/ A new representation of the Fourier transform in terms of time and scale localization is discussed that uses a newly coined A-wavelet transform (Grigoryan 2005). The A-wavelet transform uses cosine- and sine-wavelet type functions, which employ, respectively, cosine and sine signals of length . For a given frequency , the cosine- and sine-wavelet type functions are evaluated at time points separated by on the time-axis. This is a two-parameter representation of a signal in terms of time and scale (frequency), and can find out frequency contents present in the signal at any time point using less computation. In this paper, we extend this work to provide further signal information in a better way and name it as -wavelet transform. In our proposed work, we use cosine and sine signals defined over the time intervals, each of length , , and are nonnegative integers, to develop cosine- and sine-type wavelets. Using smaller time intervals provides sharper frequency localization in the time-frequency plane as the frequency is inversely proportional to the time. It further reduces the computation for evaluating the Fourier transform at a given frequency. The A-wavelet transform can be derived as a special case of the -wavelet transform. Satish Chand Copyright © 2014 Satish Chand. All rights reserved. Spatial Multiple Description Coding for Scalable Video Streams Mon, 25 Aug 2014 07:53:15 +0000 http://www.hindawi.com/journals/ijdmb/2014/132621/ The need for adapting video stream delivery over heterogeneous and unreliable networks requires self-adaptive and error resilient coding. Network bandwidth fluctuations can be handled by means of a video coding scheme which adapts to the channel conditions. However, packet losses which are frequent in wireless networks can cause a mismatch during the reconstruction in the receiver end and result in an accumulation of errors which deteriorates the quality of the delivered video. A combination of multiple description coding in pixel domain and scalable video coding schemes which addresses both video adaptation and robustness to data loss is proposed in this paper. The proposed scheme combines error concealment with spatial video scalability. In order to improve the fidelity of the reconstructed to the original frames in presence of packet loss, a multilayer polyphase spatial decomposition algorithm is proposed. Classical multiple description methods interpolate the missing data which results in smoothing and artifact at object boundaries. The proposed algorithm addresses the quality degradation due to low-pass filtering effect of interpolation methods. We also comparatively analyze the trade-off between robustness to channel errors and coding efficiency. Roya Choupani, Stephan Wong, and Mehmet Tolun Copyright © 2014 Roya Choupani et al. All rights reserved. A Model for Video Quality Assessment Considering Packet Loss for Broadcast Digital Television Coded in H.264 Thu, 03 Apr 2014 11:15:53 +0000 http://www.hindawi.com/journals/ijdmb/2014/242531/ This paper presents a model to predict video quality perceived by the broadcast digital television (DTV) viewer. We present how noise on DTV can introduce individual transport stream (TS) packet losses at the receiver. The type of these errors is different than the produced on IP networks. Different scenarios of TS packet loss are analyzed, including uniform and burst distributions. The results show that there is a high variability on the perceived quality for a given percentage of packet loss and type of error. This implies that there is practically no correlation between the type of error or the percentage of packets loss and the perceived degradation. A new metric is introduced, the weighted percentage of slice loss, which takes into account the affected slice type in each lost TS packet. We show that this metric is correlated with the video quality degradation. A novel parametric model for video quality estimation is proposed, designed, and verified based on the results of subjective tests in SD and HD. The results were compared to a standard model used in IP transmission scenarios. The proposed model improves Pearson Correlation and root mean square error between the subjective and the predicted MOS. Jose Joskowicz and Rafael Sotelo Copyright © 2014 Jose Joskowicz and Rafael Sotelo. All rights reserved. Performance Evaluation of Concurrent Multipath Video Streaming in Multihomed Mobile Networks Mon, 26 Aug 2013 16:12:34 +0000 http://www.hindawi.com/journals/ijdmb/2013/319594/ High-quality real-time video streaming to users in mobile networks is challenging due to the dynamically changing nature of the network paths, particularly the limited bandwidth and varying end-to-end delay. In this paper, we empirically investigate the performance of multipath streaming in the context of multihomed mobile networks. Existing schemes that make use of the aggregated bandwidth of multiple paths can overcome bandwidth limitations on a single path but suffer an efficiency penalty caused by retransmission of lost packets in reliable transport schemes or path switching overheads in unreliable transport schemes. This work focuses on the evaluation of schemes to permit concurrent use of multiple paths to deliver video streams. A comprehensive streaming framework for concurrent multipath video streaming is proposed and experimentally evaluated, using current state-of-the-art H.264 Scalable Video Coding (H.264/SVC) and the next generation High Efficiency Video Coding (HEVC) standards. It provides a valuable insight into the benefit of using such schemes in conjunction with encoder specific packet prioritisation mechanisms for quality-aware packet scheduling and scalable streaming. The remaining obstacles to deployment of concurrent multipath schemes are identified, and the challenges in realising HEVC based concurrent multipath streaming are highlighted. James Nightingale, Qi Wang, and Christos Grecos Copyright © 2013 James Nightingale et al. All rights reserved. Optimization of ATSC Mobile Handheld Service Capacity Sun, 24 Mar 2013 10:01:08 +0000 http://www.hindawi.com/journals/ijdmb/2013/837153/ Mobile TV has become a reality offered on several mobile delivery systems. Among them is the Advanced Television System Committee (ATSC) system for mobile and handheld digital television services, known as ATSC Mobile DTV or ATSC M/H, which has moved from standardization to implementation. As the North American broadcast industry is preparing to provide Mobile DTV service to consumers, this work discusses important technical parameters that affect the TV service quality and capacity. Since additional error correction mechanisms were added to overcome mobile transmission problems, the available payload for M/H services is limited. This creates a need to efficiently use the available M/H bandwidth. The paper aims to optimize the Mobile DTV service capacity while maintaining an acceptable perceived quality. It presents tradeoffs between several factors affecting service capacity and signal robustness, which is prominent for designing Mobile TV broadcasting scenarios. Omneya Issa Copyright © 2013 Omneya Issa. All rights reserved. Bandwidth Management in Wireless Home Networks for IPTV Solutions Tue, 05 Mar 2013 10:55:14 +0000 http://www.hindawi.com/journals/ijdmb/2013/474212/ The optimal allocation of the retransmission bandwidth is essential for IPTV service providers to ensure maximal service quality. This paper highlights the relevance of the wireless transport in today’s IPTV solution and discusses how this new media affects the existing broadcast technologies. A new Markovian channel model is developed to address the optimization issues of the retransmission throughput, and a new method is presented which is evaluated by empirical measurements followed by mathematical analysis. Tamás Jursonovics and Sándor Imre Copyright © 2013 Tamás Jursonovics and Sándor Imre. All rights reserved. Client-Driven Joint Cache Management and Rate Adaptation for Dynamic Adaptive Streaming over HTTP Wed, 27 Feb 2013 12:30:10 +0000 http://www.hindawi.com/journals/ijdmb/2013/471683/ Due to the fact that proxy-driven proxy cache management and the client-driven streaming solution of Dynamic Adaptive Streaming over HTTP (DASH) are two independent processes, some difficulties and challenges arise in media data management at the proxy cache and rate adaptation at the DASH client. This paper presents a novel client-driven joint proxy cache management and DASH rate adaptation method, named CLICRA, which moves prefetching intelligence from the proxy cache to the client. Based on the philosophy of CLICRA, this paper proposes a rate adaptation algorithm, which selects bitrates for the next media segments to be requested by using the predicted buffered media time in the client. CLICRA is realized by conveying information on the segments that are likely to be fetched subsequently to the proxy cache so that it can use the information for prefetching. Simulation results show that the proposed method outperforms the conventional segment-fetch-time-based rate adaptation and the proxy-driven proxy cache management significantly not only in streaming quality at the client but also in bandwidth and storage usage in proxy caches. Chenghao Liu, Miska M. Hannuksela, and Moncef Gabbouj Copyright © 2013 Chenghao Liu et al. All rights reserved. PAPR Reduction of OFDM Signals by Novel Global Harmony Search in PTS Scheme Thu, 06 Dec 2012 13:54:10 +0000 http://www.hindawi.com/journals/ijdmb/2012/940849/ The orthogonal frequency division multiplexing (OFDM) modulation technique is one of the key strategies for multiuser signal transmission especially in smart grids and wind farms. This paper introduces an approach for peak-to-average power ratio (PAPR) reduction of such signals based on novel global harmony search (NGHS) and partial transmit sequence (PTS) schemes. In PTS technique, the data block to be transmitted is partitioned into disjoint subblocks, which are combined using phase factors to minimize PAPR. The PTS requires an exhaustive search over all combinations of allowed phase factors. Therefore, with respect to the fast implementation and simplicity of NGHS technique, we could achieve significant reduction of PAPR. Hojjat Salehinejad and Siamak Talebi Copyright © 2012 Hojjat Salehinejad and Siamak Talebi. All rights reserved. IPTV: Technology, Practice, and Service Sun, 26 Aug 2012 08:29:00 +0000 http://www.hindawi.com/journals/ijdmb/2012/734769/ Hsiang-Fu Yu, Jen-Wen Ding, Pin-Han Ho, and János Tapolcai Copyright © 2012 Hsiang-Fu Yu et al. All rights reserved. Background Traffic-Based Retransmission Algorithm for Multimedia Streaming Transfer over Concurrent Multipaths Mon, 13 Aug 2012 10:21:32 +0000 http://www.hindawi.com/journals/ijdmb/2012/789579/ The content-rich multimedia streaming will be the most attractive services in the next-generation networks. With function of distribute data across multipath end-to-end paths based on SCTP's multihoming feature, concurrent multipath transfer SCTP (CMT-SCTP) has been regarded as the most promising technology for the efficient multimedia streaming transmission. However, the current researches on CMT-SCTP mainly focus on the algorithms related to the data delivery performance while they seldom consider the background traffic factors. Actually, background traffic of realistic network environments has an important impact on the performance of CMT-SCTP. In this paper, we firstly investigate the effect of background traffic on the performance of CMT-SCTP based on a close realistic simulation topology with reasonable background traffic in NS2, and then based on the localness nature of background flow, a further improved retransmission algorithm, named RTX_CSI, is proposed to reach more benefits in terms of average throughput and achieve high users' experience of quality for multimedia streaming services. Yuanlong Cao, Changqiao Xu, Jianfeng Guan, and Hongke Zhang Copyright © 2012 Yuanlong Cao et al. All rights reserved. Secure and Reliable IPTV Multimedia Transmission Using Forward Error Correction Sun, 08 Jul 2012 10:42:03 +0000 http://www.hindawi.com/journals/ijdmb/2012/720791/ With the wide deployment of Internet Protocol (IP) infrastructure and rapid development of digital technologies, Internet Protocol Television (IPTV) has emerged as one of the major multimedia access techniques. A general IPTV transmission system employs both encryption and forward error correction (FEC) to provide the authorized subscriber with a high-quality perceptual experience. This two-layer processing, however, complicates the system design in terms of computational cost and management cost. In this paper, we propose a novel FEC scheme to ensure the secure and reliable transmission for IPTV multimedia content and services. The proposed secure FEC utilizes the characteristics of FEC including the FEC-encoded redundancies and the limitation of error correction capacity to protect the multimedia packets against the malicious attacks and data transmission errors/losses. Experimental results demonstrate that the proposed scheme obtains similar performance compared with the joint encryption and FEC scheme. Chi-Huang Shih, Yeong-Yuh Xu, and Yao-Tien Wang Copyright © 2012 Chi-Huang Shih et al. All rights reserved. Automatic Story Segmentation for TV News Video Using Multiple Modalities Thu, 05 Jul 2012 10:04:20 +0000 http://www.hindawi.com/journals/ijdmb/2012/732514/ While video content is often stored in rather large files or broadcasted in continuous streams, users are often interested in retrieving only a particular passage on a topic of interest to them. It is, therefore, necessary to split video documents or streams into shorter segments corresponding to appropriate retrieval units. We propose here a method for the automatic segmentation of TV news videos into stories. A-multiple-descriptor based segmentation approach is proposed. The selected multimodal features are complementary and give good insights about story boundaries. Once extracted, these features are expanded with a local temporal context and combined by an early fusion process. The story boundaries are then predicted using machine learning techniques. We investigate the system by experiments conducted using TRECVID 2003 data and protocol of the story boundary detection task, and we show that the proposed approach outperforms the state-of-the-art methods while requiring a very small amount of manual annotation. Émilie Dumont and Georges Quénot Copyright © 2012 Émilie Dumont and Georges Quénot. All rights reserved. QoS Supported IPTV Service Architecture over Hybrid-Tree-Based Explicit Routed Multicast Network Tue, 03 Jul 2012 08:43:47 +0000 http://www.hindawi.com/journals/ijdmb/2012/263470/ With the rapid advance in multimedia streaming and multicast transport technology, current IP multicast protocols, especially PIM-SM, become the major channel delivery mechanism for IPTV system over Internet. The goals for IPTV service are to provide two-way interactive services for viewers to select popular program channel with high quality for watching during fast channel surfing period. However, existing IP multicast protocol cannot meet above QoS requirements for IPTV applications between media server and subscribers. Therefore, we propose a cooperative scheme of hybrid-tree based on explicit routed multicast, called as HT-ERM to combine the advantages of shared tree and source tree for QoS-supported IPTV service. To increase network utilization, the constrained shortest path first (CSPF) routing algorithm is designed for construction of hybrid tree to deliver the high-quality video stream over watching channel and standard quality over surfing channel. Furthermore, the Resource Reservation Protocol- Traffic Engineering (RSVP-TE) is used as signaling mechanism to set up QoS path for multicast channel admission control. Our simulation results demonstrated that the proposed HT-ERM scheme outperforms other multicast QoS-based delivery scheme in terms of channel switching delay, resource utilization, and blocking ratio for IPTV service. Chih-Chao Wen and Cheng-Shong Wu Copyright © 2012 Chih-Chao Wen and Cheng-Shong Wu. All rights reserved. Rate Adaptive Selective Segment Assignment for Reliable Wireless Video Transmission Wed, 27 Jun 2012 10:41:27 +0000 http://www.hindawi.com/journals/ijdmb/2012/160521/ A reliable video communication system is proposed based on data partitioning feature of H.264/AVC, used to create a layered stream, and LT codes for erasure protection. The proposed scheme termed rate adaptive selective segment assignment (RASSA) is an adaptive low-complexity solution to varying channel conditions. The comparison of the results of the proposed scheme is also provided for slice-partitioned H.264/AVC data. Simulation results show competitiveness of the proposed scheme compared to optimized unequal and equal error protection solutions. The simulation results also demonstrate that a high visual quality video transmission can be maintained despite the adverse effect of varying channel conditions and the number of decoding failures can be reduced. Sajid Nazir, Dejan Vukobratović, Vladimir Stanković, and Ivan Andonović Copyright © 2012 Sajid Nazir et al. All rights reserved.