A.B.B. Adikari

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

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

Unidirectional Distributed Video Coding for Low Cost Video Encoding

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.

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

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.

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

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

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

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.

A H.264 compliant stereoscopic video codec

Due to the provision of a more natural representation of a scene in the form of left and right eye views, a stereoscopic imaging system provides a more effective method for image/video display. Unfortunately the vast amount of information that needs to be transmitted/stored to represent a stereo image pair/video sequence, has so far hindered its use in commercial applications. However, by properly exploiting the spatial, temporal and binocular redundancy, a stereo image pair or a sequence could be compressed and transmitted through a single monocular channels bandwidth without unduly sacrificing the perceived stereoscopic image quality. In this paper, we present a new technique for coding stereo video sequences based on H.264 video codec. The proposed codec exploits disparity and worldline correlation in addition to the advance compression techniques inherited by the H.264 standard to achieve a higher video quality especially in the low bit rates. We compare the performance of the proposed CODEC with a DCT-based, modified MPEG-2 stereo video CODEC and ZTE based stereo video CODEC. We show that the proposed CODEC outperforms the benchmark CODECs in coding both main and auxiliary streams by up to 9.0 dB PSNR gain

Bitplane Based Wyner-Ziv Coding using Unequal Error Protection

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

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

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.

Side Information Improvement in DVC with Two Side Information Streams and 3D Motion Refinement

Distributed video coding (DVC) has become increasingly popular in recent times among the researchers in video coding due to its attractive and promising features. DVC primarily has a modified complexity balance between the encoder and decoder, in contrast to conventional video codecs. 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 enhanced algorithm is proposed for the side information generation process where the side information is evolved over the processing of each bit plane. Simulation results of the proposed technique depict a consistent improvement in performance in comparison to the state-of-the-art in pixel domain DVC.

Low Complex Key Frame Encoding with High Quality Wyner-Ziv Coding

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