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Dive into the research topics where W.A.R.J. Weerakkody is active.

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Featured researches published by W.A.R.J. Weerakkody.


international conference on multimedia and expo | 2007

An Iterative Refinement Technique for Side Information Generation in DVC

W.A.R.J. Weerakkody; W.A.C. Fernando; José Luis Martínez; Pedro Cuenca; Francisco J. Quiles

Distributed video coding (DVC) is an increasingly popular approach among the researchers in video coding during past few years due to its attractive and promising features. In DVC, the majority of the computational complexity has been shifted from encoder to the decoder in comparison to its conventional counterparts, including MPEG and H.26 x enabling a dramatically low cost encoder implementation. Side information generation, carried out at the decoder, is a major function in the DVC coding algorithm and plays a key-role in determining the performance of the codec. In this paper, a novel iterative refinement technique is proposed for the side information generation process. Simulation results of the proposed technique depict a consistent improvement in performance in comparison to the state-of-the-art in pixel domain DVC.


canadian conference on electrical and computer engineering | 2006

Unequal Error Protection Technique for ROI Based H.264 Video Coding

H.K. Arachchi; W.A.C. Fernando; S. Panchadcharam; W.A.R.J. Weerakkody

This paper presents a region of interest (ROI) based video coding technique for H.264 based video coding with improved error resilience and error protection in the foreground. We used the flexible macroblock ordering (FMO) tool in H.264 video coding standard to encode the video frame into three separate slices. First slice carries the background, and other two slices contains alternative macroblock of the foreground forming a check board pattern. Foreground packets are protected with a stronger error correction code than background packets. Experimental results show that the proposed technique improves the objective quality of the foreground by more than 1 dB


canadian conference on electrical and computer engineering | 2006

Wyner-Ziv Coding with Temporal and Spatial Correlations for Motion Video

A.B.B. Adikari; W.A.C. Fernando; H.K. Arachchi; W.A.R.J. Weerakkody

Distributed video coding (DVC), now has become one of the fastest evolving coding techniques in the current signal processing world. It has its remarkable low complex yet powerful encoder which is essential for some applications in the consumer market. In this paper we propose a novel Wyner-Ziv architecture that splits a frame in to two sub frames and leave one as a key sub frame while encoding the other as a WZ sub frame. The split key sub frame is encoded using a conventional coding scheme as in the other DVC techniques. At the decoder end the sub key frame is used to exploit the spatial and temporal correlations using an intra prediction technique and temporal motion search in order to generate the side information for the corresponding WZ sub frame. Simulation results show that over 1 dB PSNR gain can be obtained with the proposed algorithm over the results of the algorithm presented in the literature at the same bit rate


IEEE Transactions on Consumer Electronics | 2007

Unidirectional Distributed Video Coding for Low Cost Video Encoding

W.A.R.J. Weerakkody; W.A.C. Fernando; A.B.B. Adikari

Distributed video coding (DVC) is an emerging video coding approach in the new era, particularly attractive due to its flexibility to introduce very simple encoder structures. This feature could be very effectively utilized in the design of low cost video cameras. However, the DVC architecture commonly discussed in research literature has a fundamental drawback of involving a feedback channel between the encoder and the decoder, which restrains itself from being used in video storage based applications. In this paper, we discuss a solution to the above problem in DVC, with a novel unidirectional architecture. In the proposed design, the feedback channel is suppressed and the encoded (compressed) bit stream can be transferred onto storage media for offline processing. The proposed decoder uses the spatial and temporal properties of the video sequence to refine the side information for iterative decoding, with the repeated use of same parity bit stream. The simulation results depict a significantly improved performance over other conventional video coding techniques proposed for use in low to middle end video equipments, while involving a very low encoder complexity.


international conference on image processing | 2006

A Sequential Motion Compensation Refinement Technique for Distributed video coding of Wyner-Ziv frames

A.B.B. Adikari; W.A.C. Fernando; W.A.R.J. Weerakkody; H.K. Arachchi

Distributed video coding (DVC) is one of the fastest growing coding techniques in the current signal processing world. It has its outstanding low complex encoder which is essential for some applications in the consumer market. Driven by the above motive, in this paper we propose a novel side information refinement technique for Wyner-Ziv video frames in DVC. When a bit plane is decoded, it is used to replace the corresponding bit plane in the side information and used for motion estimation and compensation to up date the side information. Then the information for the next bit plane is extracted from the updated side information and is sent to the turbo decoder as in a conventional DVC decoder. This process is repeated until all bit planes are extracted. This technique can be employed with almost all the side information generation techniques from simplest conventional pixel interpolation to advanced techniques such as bi-directional motion estimation and spatial motion smoothing (BiMESS). Simulation results show that over 1.4 dB PSNR gain can be obtained with the proposed algorithm over the BiMESS smoothing algorithm at the same bit rate.


canadian conference on electrical and computer engineering | 2006

Distributed Video Coding of Wyner-Ziv Frames using Trellis Coded Modulation

W.A.R.J. Weerakkody; W.A.C. Fernando; A.B.B. Adikari

Distributed video coding (DVC) is known as an emerging video coding technique, which primarily has a modified complexity balance in the encoder and decoder, in contrast to its traditional competitors. In DVC, we have a very simple low cost encoder which is an ideal feature for applications involving a large number of video capturing points located remotely and a centralized shared decoder. In this paper, we introduce a novel approach for DVC, using turbo trellis coded modulation (TTCM) to generate the parity information at the encoder to be sent over the channel and then to decode the parity with the side information at the decoder. The side information is generated using key frames passed to the decoder by the use of a pixel interpolation technique. TCM symbols are formed using the side information and the parity bit stream which are fed to the TTCM decoder. The decoded output is used to reconstruct the final video sequence. The results are compared with a turbo coding based DVC and it is evident that the proposed method outperforms its turbo code based counterpart by a significant margin


international conference on image processing | 2006

Distributed video coding of Wyner-Ziv frames using Turbo Trellis Coded Modulation

W.A.R.J. Weerakkody; W.A.C. Fernando; A.B.B. Adikari; R.M.A.P. Rajatheva

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.


canadian conference on electrical and computer engineering | 2006

Bitplane Based Wyner-Ziv Coding using Unequal Error Protection

W.A.R.J. Weerakkody; W.A.C. Fernando; A.B.B. Adikari; Q. Fang

In this paper, we discuss a novel approach to distributed video coding (DVC) using bitplane based unequal error protection. Distributed video coding (DVC) has recently attracted a vast amount of attention from the video coding community all around the world, since it could prove very well suited for some applications where low-complexity encoders are a must. The primary feature of DVC is its modified complexity balance in the encoder and decoder, in contrast to its traditional competitors. When considering each pixel of the frame, out of the 8 bits it constitutes, each bit position has a different significance decreasing gradually from the MSB to the LSB. Therefore a scheme which protects the initial bitplanes better would undoubtedly be desirable. Here we propose to protest each bitplane considering its significance using variable memory length in the encoder. Since increasing the memory length results in higher computational complexity, the optimum mix of the memory length is to be evaluated for the codec to operate within the conceptual restrictions of low-complex encoder in DVC. In this paper, the proposed codec is compared for peformance with another DVC codec which uses a fixed memory length over the whole sequence with comparable complexity. Simulation results show that the proposed method outperforms its fixed memory length counterpart t by a significant margin


IEICE Electronics Express | 2006

4-PSK TTCM for Wyner-Ziv frame coding in DVC

W.A.R.J. Weerakkody; W.A.C. Fernando; A.B.B. Adikari; R.M.A.P. Rajatheva

This paper proposes a novel approach for the implementation of Distributed Video coding (DVC) using 4-PSK turbo trellis coded modulation (TTCM). We have adapted the TTCM concept for source coding by generating parity at the encoder and transferring the symbol mapping to the decoder. The parity bits are sent to the decoder with puncturing as in a turbo based DVC codecs and combined with side information to form the symbols used in the TTCM decoder. The side information is generated by basic frame interpolation. The proposed codec was tested with different test video sequences and the results obtained show up to 6dB improvement in PSNR with less memory for the same bit rate when compared with the turbo coding based DVC codecs.


canadian conference on electrical and computer engineering | 2007

MIMO Wireless Channel for Video Communications using Distributed Video Coding

K. Muraleetharan; W.A.C. Fernando; W.A.R.J. Weerakkody; R.M.A.P. Rajatheva

The research on distributed video coding (DVC) has been increasingly popular in recent times due to its promising features. DVC primarily has a modified complexity balance between the encoder and decoder, in contrast to conventional video codecs. In video communications over wireless channels, the noise and multipath fading effects have a significant effect on the perceptual video quality experienced at the decoder. However, it is noted that in all the research literature on DVC, an error-free ideal communication channel is assumed between the encoder and decoder. In this paper, we take into account the effects of noise and fading in a wireless channel on the performance of a DVC codec with necessary modifications to the decoding algorithm while proposing a higher order (4x4) MIMO based diversity scheme to take advantage of the multipath propagation effects to improve the performance. Simulation results show that the proposed DVC system outperform the state of the art H.264 video codec at low SNR levels.

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A.B.B. Adikari

Brunel University London

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H.K. Arachchi

Brunel University London

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R.M.A.P. Rajatheva

Asian Institute of Technology

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Q. Fang

Brunel University London

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