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Distributed Video Coding of Wyner-Ziv Frames using Trellis Coded Modulation
Abstract
In this paper, we present a novel distributed video coding algorithm based on turbo trellis coded modulation (TTCM). As in the conventional turbo based Slepian-Wolf encoder, quantised information is applied to the TTCM encoder and parity bits are generated from both constituent encoders. However, TTCM symbols are not generated at the encoder since they are not sent to the decoder. Parity bits produced by the TTCM encoder are stored in a buffer and transmitted to the decoder upon request. TTCM symbols are generated at the decoder and these symbols are passed to the TTCM decoder for demodulation. Experimental results show that the proposed TTCM based codec can improve the PSNR by up to 6 dB at the same bit rate with less memory compared to the turbo coded distributed video codecs
... The majority of these well-know research works on DVC have been carried out using a Turbo Wyner-Ziv codec. However, recent experimental results [6] show that the Turbo Trellis Coded Modulation (TTCM) based DVC codecs can improve the PSNR up to 6dB at the same bit rate with less memory compared to the Turbo Coded DVC codecs. Current practical schemes developed for DVC are based in general on the following principles: the video frames are organized into two types; Key frames and Wyner-Ziv frames, while the key frames are encoded with a conventional intraframe codec, the frames between them are Wyner-Ziv encoded. ...
... However, these conventional intraframe encoders are too complex to be implemented in a DVC low-complexity scenario. For this reason, this paper present a DVC architecture based on TTCM codes for the Wyner-Ziv frames as proposed in [6] and on LTW for the key frames as proposed in [9]. This paper is an integration and evaluation of these two architectures. ...
... However, most interestingly, it was noted that our implementation of the codec was not susceptible to error by sub-optimal approximations of the distribution for the purpose of taking the results; an Additive White Gaussian Noise (AWGN) with variance 0.125 was assumed. To obtain more details about this, see [6].Figure 2. Block Diagram of TTCM Decoder ...
Distributed Video Coding (DVC) is a promising coding solution for some emerging applications, where the encoder complexity, power consumption or memory requirements are constraint the system resources. Current approaches to DVC focus on improving the performance of the Wyner- Ziv coding by improving the quality of the reconstructed side information or by improving the quality of channel codes. Up to date, no attention has been paid to the problem of key frames coding where a low-encoding complexity scenario is also needed. This work focuses on key frames coding in its effect to the Wyner-Ziv frames decoding aiming to implement a very low-complexity Turbo Trellis Coded Modulation (TTCM) based DVC architecture. In this paper, we propose a new key frame coding scheme which has very low complexity and memory requirements for the TTCM based distributed video codec. Results show that the proposed intra frame codec for key frame coding outperforms the JPEG2000 and the Intra H.264 AVC codecs in terms of encoding-time and memory requirements, with better RD performance.
... The parity bit stream received from the encoder is used in the turbo decoder for achieving the above purpose. Turbo coding was proposed by Berrou et al. in 1993 for channel coding in communications [11]. This concept has been successfully adopted for DVC. ...
... On the other hand, Sect. 4.1 describes TTCM as an extension of turbo codes and which has been demonstrated in our previous works based on pixel domain [11] to be able to improve the PSNR at the same bitrate with less memory compared to the turbo coded pixel domain. Within this framework , in this work we continue to improve the performance of our pixel domain TTCM based architecture into a further paradigm, i.e., transform domain TTCM based DVC codec.Figure 10 shows the block diagram of the proposed video codec implementation in transform domain. ...
Distributed Video Coding (DVC) has been proposed for increasingly new application domains. This rise is apparently motivated
by the very attractive features of its flexibility for building very low cost video encoders and the very high built-in error
resilience when applied over noisy communication channels. Yet, the compression efficiency of DVC is notably lagging behind
the state-of-the-art in video coding and compression, H.264/AVC in particular. In this context, a novel coding solution for
DVC is presented in this paper, which promises to improve its rate-distortion (RD) performance towards the state-of-the-art.
Here, Turbo Trellis Coded Modulation (TTCM), with its attractive coding gain in channel coding, is utilized and its resultant
impact in both pixel domain and transform domain DVC framework is discussed herein. Simulations have shown a significant gain
in the RD performance when compared with the state-of-the-art Turbo coding based DVC implementations.
The quantum key reconciliation is an essential step of QKD protocol. Its main objective is to correct the transmission error after the distribution of quantum objects over a quantum channel, where two legitimate parties use a classical interactive communication for agreeing on their common key. This paper presents an alternative quantum key reconciliation method based on the Slepian-Wolf coding scheme with the chosen optimal set of BCH code rates as close to the Slepian-Wolf bound. In the proposed scheme, the BCH decoder is modified by adding one-bit feedback based on syndrome decoding to detect uncorrectable errors whenever the decoding process fails. The performance evaluation of this proposed scheme can achieve the reconciliation efficiency and reduce the cost of interactive communication via an error-free public channel comparable to the well-known reconciliation protocols. It is then suitable to apply for higher-speed discrete-variable QKD applications.
In recent years, with emerging applications such as wireless video surveillance, multimedia sensor networks, disposable video
cameras, medical applications and mobile camera phones, the traditional video coding architecture is being challenged. For
these emerging applications, Distributed Video Coding (DVC) seems to be able to offer efficient and low-complexity encoding video compression. In this paper, we present a novel
transform domain distributed video coding algorithm based on Turbo Trellis Coded Modulation (TTCM). As in the conventional turbo based Wyner-Ziv encoder, transform quantized coefficients are applied to the TTCM encoder
and parity bits are generated from both constituent encoders. However, TTCM symbols are not generated at the encoder since
they are not sent to the decoder. Parity bits produced by the TTCM encoder are stored in a buffer and transmitted to the decoder
upon request. TTCM symbols are generated at the decoder and these symbols are passed to the TTCM decoder for demodulation.
Experimental results show that significant rate-distortion (RD) gains compared to the state-of-the-art results available in
the literature can be obtained.
Distributed Video Coding is a new coding technique which has been evolving very fast recently. However the rate distortion
performances of current solutions are below the expectations especially for high motion sequences even at a group of picture
(GOP) size of 2. Main reason of this problem is the temporal prediction of the Wyner-Ziv (WZ) frames at the decoder. In this
paper we propose a novel transform domain DVC codec architecture which splits each frame into two sub-frames and they are
encoded separately as key sub-frame and WZ sub-frame. Pixel interpolation or median prediction techniques are utilized to
generate the side information at the decoder. Simulation results show that a significant rate distortion improvement can be
obtained with the proposed algorithm over the current DVC solutions.
Distributed Video Coding (DVC) is an emerging video coding approach, particularly attractive due to its flexibility to implement low complex encoders. This feature could be very effectively utilized in a number of video sensor based application scenarios. However, DVC is still in the process of development and currently available codec implementations are based on a number of hypothetical models and assumptions. In DVC, the effects of noise and fading on the compressed payload (parity bit stream) in real video communications and the resultant modified channel model scenario have not been discussed in literature. In this paper, a solution to the above problem in turbo coding based DVC is discussed incorporating a novel dual channel model for the maximum a-posteriori (MAP) algorithm for turbo decoding. The simulations for AWGN and wireless channels at different group of picture (GOP) sizes show that the proposed algorithm improves the rate distortion performance compared to the existing decoding algorithm. It also outperforms the H.264/AVC I-P-I-P codec (v10.1/baseline profile); particularly at low Signal to Noise Ratio (SNR) levels of the channel, thus enabling DVC as a viable and efficient option for video communications.
DVC based video codecs proposed in the literature generally include a reverse (feedback) channel between the encoder and the decoder. This channel is used to communicate the dynamic parity bit request messages from the decoder to the encoder resulting in an optimum dynamic variable rate control implementation. However it is observed that this dynamic feedback mechanism is a practical hindrance in a number of practical consumer electronics applications. In this paper we proposed a novel transform domain Unidirectional Distributed Video Codec (UDVC) without a feedback channel. First, all Wyner-Ziv frames are divided into rectangular macroblocks. A simple metric is used for each block to represent the correlations between the corresponding blocks in the adjacent key frame and the Wyner-Ziv frame. Based on the value of this metric, parity is allocated dynamically for each block. These parities are either stored for offline processing or transmitted to the DVC decoder for on line processing. Simulation results show that the proposed codec outperforms the existing UDVC solutions by a significant margin.
In this paper, we propose a novel concept for key frame encoding in distributed video codecs (DVC) without using any additional coding scheme. The proposed concept is an extension of Wyner-Ziv coding for key frame coding. Since key frames are used in the prediction purposes, the quality of them is critical in the DVC codecs. Therefore we use a fine quantizer (high quality) to encode these key frames. Side information is generated as in the conventional DVC codecs for Wyner-Ziv frames and the decoder requests parity information from the encoder based on this side information until it decodes the complete frame with a predetermined picture quality. Simulation results show that, up to 8 dB PSNR gain can be obtained with the proposed algorithm over H.264 intra frame encoding at the same bit rate
Distributed video coding (DVC) is a new compression paradigm based on two key Information Theory results: the Slepian-Wolf and Wyner-Ziv theorems. A particular case of DVC deals with lossy source coding with side information at the decoder (Wyner-Ziv) and enables to shift the coding complexity from the encoder to the decoder. The solution here described is based on a very lightweight encoder leaving for the decoder the time consuming motion estimation/compensation task. In this paper, the performance of the pixel domain distributed video codec is improved by using better side information based derived by motion compensated frame interpolation algorithms at the decoder. Besides forward and bidirectional motion estimation, a spatial motion smoothing algorithm to eliminate motion outliers is proposed. This allows significant improvements in the rate-distortion (RD) performance without sacrificing the encoder complexity.
Distributed Video Coding (DVC) is a new video coding approach based on the Wyner-Ziv theorem. Unlike most of the existing video codecs, each frame is encoded separately (either as a key-frame or a Wyner-Ziv frame) which results in a simpler and lighter encoder since complex operations like motion estimation are not performed. The previously decoded frames are used at the decoder to es timate the Wyner-Ziv frames - the frames are coded independently but jointly decoded. To have a low-delay codec, the side information frames (estimation of the Wyner-Ziv frames to be decoded ) must be extrapolated from past frames. This paper proposes a robust extrapolation module to generate the side information based on motion field smoothening to provide improved performance in the context of a low-delay pixel-domain DVC codec.
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 distributed source coding principles. We study the effect of integrating 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 analytical results obtained by modeling the video signal along the motion trajectories as a first order auto-regressive process. We show 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 sequences are coded at low bitrates.
A hierarchical structure for sports event classification based on audio and video content analysis is proposed in this paper. Compared to the event classifications in other games, those of cricket are very challenging and yet unexplored. We have successfully solved cricket video classification problem using a six level hierarchical structure. The first level performs event detection based on audio energy and Zero Crossing Rate (ZCR) of short-time audio signal. In the subsequent levels, we classify the events based on video features using a Hidden Markov Model implemented through Dynamic Programming (HMM-DP) using color or motion as a likelihood function. For some of the game-specific decisions, a rule-based classification is also performed. Our proposed hierarchical structure can easily be applied to any other sports. Our results are very promising and we have moved a step forward towards addressing semantic classification problems in general.© (2005) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
In current interframe video compression systems, the encoder performs predictive coding to exploit the similarities of successive frames. The Wyner-Ziv theorem on source coding with side information available only at the decoder suggests that an asymmetric video codec, where individual frames are encoded separately, but decoded conditionally (given temporally adjacent frames) achieves similar efficiency. We report results on a Wyner-Ziv coding scheme for motion video that uses intraframe encoding, but interframe decoding. In the proposed system, key frames are compressed by a conventional intraframe codec and in-between frames are encoded using a Wyner-Ziv intraframe coder. The decoder uses previously reconstructed frames to generate side information for interframe decoding of the Wyner-Ziv frames.
This paper presents an information-theoretic study of video codecs that are based on the principle of source coding with side information at the decoder. In contrast to the classical Wyner-Ziv side-information source coding problem (1976), in this work we address the situation where the source and side-information are connected through a state of nature that is unknown to both the encoder and the decoder. We dub this framework as source encoding with side-information under ambiguous state of nature (SEASON). Our objective is to compare the achievable rate-distortion (R/D) performance of conventional video codecs designed under the motion-compensated predictive coding (MCPC) framework and video codecs designed under the SEASON framework. Our analysis shows that under appropriate motion models and for Gaussian displaced frame difference (DFD) statistics, the R/D performance of a classical MCPC-based video codec is matched by that of our proposed SEASON-based video codec, with the hitter being characterized by the novel concept of moving the motion compensation task from the encoder to the decoder.
In this paper we generalize (to nondiscrete sources) the results of a previous paper (Wyner and Ziv, 1976) on source coding with a fidelity criterion in a situation where the decoder (but not the encoder) has access to side information about the source. We define R*(d) as the minimum rate (in the usual Shannon sense) required for encoding the source at a distortion level about d. The main result is the characterization of R*(d) by an information theoretic minimization. In a special case in which the source and the side information are jointly Gaussian, it is shown that R*(d) is equal to the rate which would be required if the encoder (as well as the decoder) is informed of the side information.
The main result of this paper is the determination of R*(d), for d greater than equivalent to 0, in the general case, where R*(d) is defined as the infimum of rates R such that (with epsilon greater than 0 arbitrarily small and with suitably large n, where n is the block length) communication is possible in the special setting at an average distortion level not exceeding d plus epsilon .
In current interframe video compression systems, the encoder performs predictive coding to exploit the similarities of successive frames. The Wyner-Ziv theorem on source coding with side information available only at the decoder suggests that an asymmetric video codec, where individual frames are encoded separately, but decoded conditionally (given temporally adjacent frames) could achieve similar efficiency. We report the first results on a Wyner-Ziv coding scheme for motion video that uses intraframe encoding, but interframe decoding.
Let {(X_{k}, Y_{k}) }^{ infty}_{k=1} be a sequence of independent drawings of a pair of dependent random variables X, Y . Let us say that X takes values in the finite set cal X . It is desired to encode the sequence {X_{k}} in blocks of length n into a binary stream of rate R , which can in turn be decoded as a sequence { hat{X}_{k} } , where hat{X}_{k} in hat{ cal X} , the reproduction alphabet. The average distortion level is (1/n) sum^{n}_{k=1} E[D(X_{k},hat{X}_{k})] , where D(x,hat{x}) geq 0, x in {cal X}, hat{x} in hat{ cal X} , is a preassigned distortion measure. The special assumption made here is that the decoder has access to the side information {Y_{k}} . In this paper we determine the quantity R ast (d) , defined as the infimum ofrates R such that (with varepsilon > 0 arbitrarily small and with suitably large n )communication is possible in the above setting at an average distortion level (as defined above) not exceeding d + varepsilon . The main result is that R ast (d) = inf [I(X;Z) - I(Y;Z)] , where the infimum is with respect to all auxiliary random variables Z (which take values in a finite set cal Z ) that satisfy: i) Y,Z conditionally independent given X ; ii) there exists a function f: {cal Y} times {cal Z} rightarrow hat{ cal X} , such that E[D(X,f(Y,Z))] leq d . Let R_{X | Y}(d) be the rate-distortion function which results when the encoder as well as the decoder has access to the side information { Y_{k} } . In nearly all cases it is shown that when d > 0 then R ast(d) > R_{X|Y} (d) , so that knowledge of the side information at the encoder permits transmission of the {X_{k}} at a given distortion level using a smaller transmission rate. This is in contrast to the situation treated by Slepian and Wolf [5] where, for arbitrarily accurate reproduction of {X_{k}} , i.e., d = varepsilon for any varepsilon >0 , knowledge of the side information at the-
encoder does not allow a reduction of the transmission rate.
Correlated information sequences cdots ,X_{-1},X_0,X_1, cdots and cdots,Y_{-1},Y_0,Y_1, cdots are generated by repeated independent drawings of a pair of discrete random variables X, Y from a given bivariate distribution P_{XY} (x,y) . We determine the minimum number of bits per character R_X and R_Y needed to encode these sequences so that they can be faithfully reproduced under a variety of assumptions regarding the encoders and decoders. The results, some of which are not at all obvious, are presented as an admissible rate region mathcal{R} in the R_X - R_Y plane. They generalize a similar and well-known result for a single information sequence, namely R_X geq H (X) for faithful reproduction.
Distributed coding is a new paradigm for video compression, based on Slepian and Wolf's and Wyner and Ziv's information-theoretic results from the 1970s. This paper reviews the recent development of practical distributed video coding schemes. Wyner-Ziv coding, i.e., lossy compression with receiver side information, enables low-complexity video encoding where the bulk of the computation is shifted to the decoder. Since the interframe dependence of the video sequence is exploited only at the decoder, an intraframe encoder can be combined with an interframe decoder. The rate-distortion performance is superior to conventional intraframe coding, but there is still a gap relative to conventional motion-compensated interframe coding. Wyner-Ziv coding is naturally robust against transmission errors and can be used for joint source-channel coding. A Wyner-Ziv MPEG encoder that protects the video waveform rather than the compressed bit stream achieves graceful degradation under deteriorating channel conditions without a layered signal representation.
Xcodedm+(N -1)(i, j),Xcodedm+Nl (i 1))
- Xcoded
Xcoded,m+l(i J). Xcodedm+(N -1)(i, j),Xcodedm+Nl (i 1))
Improving Frame Interpolation
- J Ascenso
- C Brites
- F Pereira
J. Ascenso, C. Brites, F. Pereira, "Improving Frame Interpolation
A MCTF Video Coding Scheme Based on Distributed Source Coding Principles
- M Tagliasaccchi
- S Tubaro