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Kannan Ramchandran - One of the best experts on this subject based on the ideXlab platform.

  • Efficient file synchronization: A Distributed Source Coding approach
    2011 IEEE International Symposium on Information Theory Proceedings, 2011
    Co-Authors: Kannan Ramchandran
    Abstract:

    The problem of reconstructing a Source sequence with the presence of decoder side-information that is mis-synchronized to the Source due to deletions is studied in a Distributed Source Coding framework. Motivated by practical applications, the deletion process is assumed to be bursty and is modeled by a Markov chain. The minimum rate needed to reconstruct the Source sequence with high probability is characterized in terms of an information theoretic expression, which is interpreted as the amount of information of the deleted content and the locations of deletions, subtracting “nature's secret”, that is, the uncertainty of the locations given the Source and side-information. For small bursty deletion probability, the asymptotic expansion of the minimum rate is computed.

  • on secure Distributed Source Coding
    Information Theory Workshop, 2007
    Co-Authors: Vinod M Prabhakaran, Kannan Ramchandran
    Abstract:

    Exploiting correlated observations at multiple remote nodes for generating a secret common randomness to facilitate secure communication of data between the terminals has been addressed by many authors [1][2][3]. But in many applications such as sensor networks, the correlated observations might themselves be the data that need to be communicated. We address this problem of secure Distributed Source Coding where we want to leak the least amount of information about the Sources to an eavesdropper who may have access to a correlated observation of its own and who can listen in on the communication between the Distributed encoders. The focus here is on minimizing the amount of information revealed to the eavesdropper rather than on minimizing the rate required to effect the communication.

  • receiver driven multicast over wireless with Distributed Source Coding and fec
    International Conference on Wireless Communications and Mobile Computing, 2007
    Co-Authors: Jiajun Wang, Kannan Ramchandran
    Abstract:

    We address the problem of robust low-delay video multicast over wireless networks and propose an MPEG/H.26x compatible receiver-driven multicast system. Distributed Source coded (DSC) data and forward error correction (FEC) coded parity data are sent to different multicast groups. Heterogeneous receivers with different bandwidth and channel conditions can dynamically switch between subscribing to FEC multicast group(s) and DSC multicast group(s) to enhance the quality of decoded video based on their individual deCoding status. Simulations show that this approach has advantages over pure-FEC based schemes and random intra-refresh, especially when the delay constraint is stringent and the transmission channel loss has a bursty nature, as is true in wireless channels.

  • robust wireless video multicast based on a Distributed Source Coding approach
    Signal Processing, 2006
    Co-Authors: Marco Tagliasacchi, Kannan Ramchandran, A Majumdar, Stefano Tubaro
    Abstract:

    In this paper, we present a scheme for robust scalable video multicast based on Distributed Source Coding principles. Unlike prediction-based coders, like MPEG-x and H.26x, the proposed framework is designed specifically for lossy wireless channels and directly addresses the problem of drift due to packet losses. The proposed solution is based on recently proposed PRISM (power efficient robust syndrome-based multimedia Coding) video Coding framework [R. Puri. K. Ramchandran, PRISM: a new robust video Coding architecture based on Distributed compression principles, in: Allerton Conference on Communication, Control and Computing, Urbana-Champaign, IL, October 2002] and addresses SNR, spatial and temporal scalability. Experimental results show that substantial gains are possible for video multicast over lossy channels as compared to standard codecs, without a dramatic increase in encoder design complexity as the number of streams increases.

  • video multicast over lossy channels based on Distributed Source Coding
    International Conference on Image Processing, 2004
    Co-Authors: A Majumdar, Kannan Ramchandran
    Abstract:

    We present an algorithm for robust scalable video multicast based on Distributed Source Coding techniques. Unlike prediction based coders, like MPEG, the proposed framework directly addresses the problem of drift due to packet losses. Building on the recently proposed PRISM video Coding framework (R. Puri and K. Ramehandran, 2002), we show that substantial gains are possible for video multicast over lossy channels as compared to standard codecs, without a dramatic increase in encoder complexity as the number of streams increases.

Sandeep S Pradhan - One of the best experts on this subject based on the ideXlab platform.

  • how to compute modulo prime power sums
    International Symposium on Information Theory, 2016
    Co-Authors: Mohsen Heidari, Sandeep S Pradhan
    Abstract:

    The problem of computing modulo prime-power sums is investigated in Distributed Source Coding as well as computation over Multiple-Access Channel (MAC). We build upon group codes and present a new class of codes called Quasi Group Codes (QGC). A QGC is a subset of a group code. These codes are not closed under the group addition. We investigate some properties of QGC's, and provide a packing and a covering bound. Next, we use these bounds to derived achievable rates for Distributed Source Coding as well as computation over MAC. We show that strict improvements over the previously known schemes can be obtained using QGC's.

  • Distributed Source Coding using abelian group codes a new achievable rate distortion region
    IEEE Transactions on Information Theory, 2011
    Co-Authors: Dinesh Krithivasan, Sandeep S Pradhan
    Abstract:

    A Distributed Source Coding problem with a joint distortion criterion that depends on the Sources and the reconstruction is considered in this work. While the prevalent trend in information theory has been to prove achievability results using Shannon's random Coding arguments, using structured random codes offer rate gains over unstructured random codes for many problems. Motivated by this, a new achievable rate-distortion region (an inner bound to the performance limit) is presented for this problem for discrete memoryless Sources based on “good” structured random nested codes built over abelian groups. For certain Sources and distortion functions, the new rate region is shown to be strictly bigger than the Berger-Tung rate region, which has been the best known achievable rate region for this problem till now. This is done using numerical plots. Achievable rates for single-user Source Coding using abelian group codes are also obtained as a corollary of the main Coding theorem. It is shown that nested linear codes achieve the Shannon rate-distortion function in the arbitrary discrete memoryless case.

  • on the achievable rates of Sources having a group alphabet in a Distributed Source Coding setting
    Allerton Conference on Communication Control and Computing, 2010
    Co-Authors: K Vinodh, V Lalitha, N Prakash, Vijay P Kumar, Sandeep S Pradhan
    Abstract:

    We consider the problem of compression via homomorphic enCoding of a Source having a group alphabet. This is motivated by the problem of Distributed function computation, where it is known that if one is only interested in computing a function of several Sources, then one can at times improve upon the compression rate required by the Slepian-Wolf bound. The functions of interest are those which could be represented by the binary operation in the group.

  • lattices for Distributed Source Coding jointly gaussian Sources and reconstruction of a linear function
    IEEE Transactions on Information Theory, 2009
    Co-Authors: Dinesh Krithivasan, Sandeep S Pradhan
    Abstract:

    Consider a pair of correlated Gaussian Sources (X 1,X 2). Two separate encoders observe the two components and communicate compressed versions of their observations to a common decoder. The decoder is interested in reconstructing a linear combination of X 1 and X 2 to within a mean-square distortion of D. We obtain an inner bound to the optimal rate-distortion region for this problem. A portion of this inner bound is achieved by a scheme that reconstructs the linear function directly rather than reconstructing the individual components X 1 and X 2 first. This results in a better rate region for certain parameter values. Our Coding scheme relies on lattice Coding techniques in contrast to more prevalent random Coding arguments used to demonstrate achievable rate regions in information theory. We then consider the case of linear reconstruction of K Sources and provide an inner bound to the optimal rate-distortion region. Some parts of the inner bound are achieved using the following Coding structure: lattice vector quantization followed by ldquocorrelatedrdquo lattice-structured binning.

  • Distributed Source Coding using syndromes discus design and construction
    IEEE Transactions on Information Theory, 2003
    Co-Authors: Sandeep S Pradhan, Kannan Ramchandran
    Abstract:

    We address the problem of compressing correlated Distributed Sources, i.e., correlated Sources which are not co-located or which cannot cooperate to directly exploit their correlation. We consider the related problem of compressing a Source which is correlated with another Source that is available only at the decoder. This problem has been studied in the information theory literature under the name of the Slepian-Wolf (1973) Source Coding problem for the lossless Coding case, and as "rate-distortion with side information" for the lossy Coding case. We provide a constructive practical framework based on algebraic trellis codes dubbed as Distributed Source Coding Using Syndromes (DISCUS), that can be applicable in a variety of settings. Simulation results are presented for Source Coding of independent and identically Distributed (i.i.d.) Gaussian Sources with side information available at the decoder in the form of a noisy version of the Source to be coded. Our results reveal the promise of this approach: using trellis-based quantization and coset construction, the performance of the proposed approach is 2-5 dB from the Wyner-Ziv (1976) bound.

Pramod Viswanath - One of the best experts on this subject based on the ideXlab platform.

  • The Gaussian Many-Help-One Distributed Source Coding Problem
    IEEE Transactions on Information Theory, 2010
    Co-Authors: Saurabha Tavildar, Pramod Viswanath, Aaron B. Wagner
    Abstract:

    Jointly Gaussian memoryless Sources are observed at N distinct terminals. The goal is to efficiently encode the observations in a Distributed fashion so as to enable reconstruction of any one of the observations, say the first one, at the decoder subject to a quadratic fidelity criterion. Our main result is a precise characterization of the rate-distortion region when the covariance matrix of the Sources satisfies a ¿tree-structure¿ condition. In this situation, a natural analog-digital separation scheme optimally trades off the Distributed quantization rate tuples and the distortion in the reconstruction: each encoder consists of a point-to-point Gaussian vector quantizer followed by a Slepian-Wolf binning encoder. We also provide a partial converse that suggests that the tree-structure condition is fundamental.

  • An Extremal Inequality Motivated by Multiterminal Information-Theoretic Problems
    IEEE Transactions on Information Theory, 2007
    Co-Authors: Pramod Viswanath
    Abstract:

    We prove a new extremal inequality, motivated by the vector Gaussian broadcast channel and the Distributed Source Coding with a single quadratic distortion constraint problems. As a corollary, this inequality yields a generalization of the classical entropy-power inequality (EPI). As another corollary, this inequality sheds insight into maximizing the differential entropy of the sum of two dependent random variables

  • An Extremal Inequality Motivated by Multiterminal Information Theoretic Problems
    2006 IEEE International Symposium on Information Theory, 2006
    Co-Authors: Pramod Viswanath
    Abstract:

    We prove a new extremal inequality, motivated by the vector Gaussian broadcast channel and the Distributed Source Coding with a single quadratic distortion constraint problem. As a corollary, this inequality yields a generalization of the classical vector entropy-power inequality (EPI). As another corollary, this inequality sheds insight into maximizing differential entropy of a sum of jointly Distributed random variables, generalizing a classical result of Cover and Zhang

  • The Gaussian Many-Help-One Distributed Source Coding Problem
    2006 IEEE Information Theory Workshop - ITW '06 Chengdu, 2006
    Co-Authors: Saurabha Tavildar, Pramod Viswanath, Aaron B. Wagner
    Abstract:

    Jointly Gaussian memoryless Sources (y1, ... , yN ) are observed at N distinct terminals. The goal is to efficiently encode the observations in a Distributed fashion so as to enable reconstruction of any one of the observations, say y1, at the decoder subject to a quadratic fidelity criterion. Our main result is a precise characterization of the rate-distortion region when the covariance matrix of the Sources satisfies a "tree-structure" condition. In this situation, a natural analog/digital separation scheme optimally trades off the Distributed quantization rate tuples and the distortion in reconstruction: each encoder consists of a point-to-point vector quantizer followed by a Slepian-Wolf binning encoder

Stefano Tubaro - One of the best experts on this subject based on the ideXlab platform.

  • COMBINING MCTF WITH Distributed Source Coding
    2016
    Co-Authors: Marco Tagliasacchi, Stefano Tubaro, Augusto Sarti, Politecnico Di Milano
    Abstract:

    Motion Compensated Temporal Filtering (MCTF) has proved to be an efficient Coding tool in the design of open-loop scalable video codecs. In this paper we propose a MCTF video Coding scheme based on lifting where the prediction step is implemented using PRISM (Power efficient, Robust, hIgh compression Syndrome-based Multimedia Coding), a video Coding framework built on dis-tributed Source Coding principles. We study the effect of integrat-ing the update step at the encoder or at the decoder side. We show that the latter approach allows to improve the quality of the side information exploited during deCoding. We present the analyti-cal results obtained by modeling the video signal along the mo-tion trajectories as an AR(i) process showing that the update step at the decoder allows to half the contribution of the quantization noise. We also include experimental results with real video data that demonstrate the potential of this approach when the video se-quences are coded at low bitrates. 1

  • robust wireless video multicast based on a Distributed Source Coding approach
    Signal Processing, 2006
    Co-Authors: Marco Tagliasacchi, Kannan Ramchandran, A Majumdar, Stefano Tubaro
    Abstract:

    In this paper, we present a scheme for robust scalable video multicast based on Distributed Source Coding principles. Unlike prediction-based coders, like MPEG-x and H.26x, the proposed framework is designed specifically for lossy wireless channels and directly addresses the problem of drift due to packet losses. The proposed solution is based on recently proposed PRISM (power efficient robust syndrome-based multimedia Coding) video Coding framework [R. Puri. K. Ramchandran, PRISM: a new robust video Coding architecture based on Distributed compression principles, in: Allerton Conference on Communication, Control and Computing, Urbana-Champaign, IL, October 2002] and addresses SNR, spatial and temporal scalability. Experimental results show that substantial gains are possible for video multicast over lossy channels as compared to standard codecs, without a dramatic increase in encoder design complexity as the number of streams increases.

  • intra mode decision based on spatio temporal cues in pixel domain wyner ziv video Coding
    International Conference on Acoustics Speech and Signal Processing, 2006
    Co-Authors: Marco Tagliasacchi, A Trapanese, Stefano Tubaro, Joao Ascenso, Catarina Brites, Fernando Pereira
    Abstract:

    Distributed Source Coding principles have been recently applied to video Coding in order to achieve a flexible distribution of the complexity burden between the encoder and the decoder. In this paper we elaborate on a pixel based Wyner-Ziv video codec that shifts all the complexity of the motion estimation phase to the decoder, thus achieving light enCoding. We observe that the correlation noise statistics describing the relationship between the frame to be encoded and the side information available at the decoder is not spatially stationary. For this reason we introduce a mode decision scheme either at the encoder or at the decoder in such a way that when the estimated correlation is weak we opt for intra Coding on a block-by-block basis. Both spatial and temporal criteria are used to determine whether a block is better intra coded or not.

  • improved correlation noise statistics modeling in frame based pixel domain wyner ziv video Coding
    International Workshop on Very Low Bitrate Video Coding (VLBV05), 2005
    Co-Authors: Joao Ascenso, Marco Tagliasacchi, A Trapanese, Catarina Brites, Fernando Pereira, Stefano Tubaro
    Abstract:

    Distributed Source Coding principles have been recently applied to video Coding in order to achieve a flexible distribution of the complexity burden between the encoder and the decoder. In this paper we elaborate on a pixel based WynerZiv video codec that shifts all the complexity of the motion estimation phase to the decoder, thus achieving light enCoding. In the literature, the statistics of correlation noise between the frame to be encoded and the motion-compensated side information available at the decoder is modeled as a Laplacian distribution. In this paper we elaborate on this topic and we show that a better model can be fitted, achieving a substantial Coding efficiency gain. Moreover we discuss the effect of using a side information computed either from perfectly reconstructed (lossless) or from quantized neighboring frames.

  • embedding a block based intra mode in frame based pixel domain wyner ziv video Coding
    2005
    Co-Authors: A Trapanese, Marco Tagliasacchi, Stefano Tubaro, Joao Ascenso, Catarina Brites, Fernando Pereira
    Abstract:

    Distributed Source Coding principles have been recently applied to video Coding in order to achieve a flexible distribution of the complexity burden between the encoder and the decoder. In this paper we elaborate on a pixel based WynerZiv video codec that shifts all the complexity of the motion estimation phase to the decoder, thus achieving light enCoding. We observe that the correlation noise statistics describing the relationship between the frame to be encoded and the side information available at the decoder is not spatially stationary. For this reason we introduce a mode decision scheme either at the encoder or at the decoder in such a way that when the estimated correlation is weak we opt for intra Coding on a block-by-block basis. Moreover we discuss the effect of using a side information computed either from lossless or from quantized frames.

Marco Tagliasacchi - One of the best experts on this subject based on the ideXlab platform.

  • COMBINING MCTF WITH Distributed Source Coding
    2016
    Co-Authors: Marco Tagliasacchi, Stefano Tubaro, Augusto Sarti, Politecnico Di Milano
    Abstract:

    Motion Compensated Temporal Filtering (MCTF) has proved to be an efficient Coding tool in the design of open-loop scalable video codecs. In this paper we propose a MCTF video Coding scheme based on lifting where the prediction step is implemented using PRISM (Power efficient, Robust, hIgh compression Syndrome-based Multimedia Coding), a video Coding framework built on dis-tributed Source Coding principles. We study the effect of integrat-ing the update step at the encoder or at the decoder side. We show that the latter approach allows to improve the quality of the side information exploited during deCoding. We present the analyti-cal results obtained by modeling the video signal along the mo-tion trajectories as an AR(i) process showing that the update step at the decoder allows to half the contribution of the quantization noise. We also include experimental results with real video data that demonstrate the potential of this approach when the video se-quences are coded at low bitrates. 1

  • Detection and identification of sparse audio tampering using Distributed Source Coding and compressive sensing techniques
    2008
    Co-Authors: Giorgio Prandi, Marco Tagliasacchi, Augusto Sarti
    Abstract:

    In most practical applications, for the sake of information integrity not only it is useful to detect whether a multimedia content has been modified or not, but also to identify which kind of attack has been carried out. In the case of audio streams, for example, it may be useful to localize the tamper in the time and/or frequency domain. In this paper we devise a hash-based tampering detection and localization system exploiting compressive sensing principles. The multimedia content provider produces a small hash signature using a limited number of random projections of a time-frequency representation of the original audio stream. At the content user side, the hash signature is used to estimate the distortion between the original and the received stream and, provided that the tamper is sufficiently sparse or sparsifiable in some orthonormal basis ex-pansion or redundant dictionary (e.g. DCT or wavelet), to identify the time-frequency portion of the stream that has been manipu-lated. In order to keep the hash length small, the algorithm exploits Distributed Source Coding techniques. 1

  • robust wireless video multicast based on a Distributed Source Coding approach
    Signal Processing, 2006
    Co-Authors: Marco Tagliasacchi, Kannan Ramchandran, A Majumdar, Stefano Tubaro
    Abstract:

    In this paper, we present a scheme for robust scalable video multicast based on Distributed Source Coding principles. Unlike prediction-based coders, like MPEG-x and H.26x, the proposed framework is designed specifically for lossy wireless channels and directly addresses the problem of drift due to packet losses. The proposed solution is based on recently proposed PRISM (power efficient robust syndrome-based multimedia Coding) video Coding framework [R. Puri. K. Ramchandran, PRISM: a new robust video Coding architecture based on Distributed compression principles, in: Allerton Conference on Communication, Control and Computing, Urbana-Champaign, IL, October 2002] and addresses SNR, spatial and temporal scalability. Experimental results show that substantial gains are possible for video multicast over lossy channels as compared to standard codecs, without a dramatic increase in encoder design complexity as the number of streams increases.

  • intra mode decision based on spatio temporal cues in pixel domain wyner ziv video Coding
    International Conference on Acoustics Speech and Signal Processing, 2006
    Co-Authors: Marco Tagliasacchi, A Trapanese, Stefano Tubaro, Joao Ascenso, Catarina Brites, Fernando Pereira
    Abstract:

    Distributed Source Coding principles have been recently applied to video Coding in order to achieve a flexible distribution of the complexity burden between the encoder and the decoder. In this paper we elaborate on a pixel based Wyner-Ziv video codec that shifts all the complexity of the motion estimation phase to the decoder, thus achieving light enCoding. We observe that the correlation noise statistics describing the relationship between the frame to be encoded and the side information available at the decoder is not spatially stationary. For this reason we introduce a mode decision scheme either at the encoder or at the decoder in such a way that when the estimated correlation is weak we opt for intra Coding on a block-by-block basis. Both spatial and temporal criteria are used to determine whether a block is better intra coded or not.

  • improved correlation noise statistics modeling in frame based pixel domain wyner ziv video Coding
    International Workshop on Very Low Bitrate Video Coding (VLBV05), 2005
    Co-Authors: Joao Ascenso, Marco Tagliasacchi, A Trapanese, Catarina Brites, Fernando Pereira, Stefano Tubaro
    Abstract:

    Distributed Source Coding principles have been recently applied to video Coding in order to achieve a flexible distribution of the complexity burden between the encoder and the decoder. In this paper we elaborate on a pixel based WynerZiv video codec that shifts all the complexity of the motion estimation phase to the decoder, thus achieving light enCoding. In the literature, the statistics of correlation noise between the frame to be encoded and the motion-compensated side information available at the decoder is modeled as a Laplacian distribution. In this paper we elaborate on this topic and we show that a better model can be fitted, achieving a substantial Coding efficiency gain. Moreover we discuss the effect of using a side information computed either from perfectly reconstructed (lossless) or from quantized neighboring frames.