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object-based video coding for Distance Learning Using Stereo Cameras

13th International-Computer-Society-of-Iran-Computer Conference

作者： Khalili, Amir Hossein Bagheri, Mojtaba Kasaei, Shohreh Sharif Univ Technol Tehran Iran

ISBN: (纸本)9783540899846

This paper presents a novel video encoding method for cooperative educational dissemination systems. Taking into consideration the inherent characteristics of stereo cameras framework in Our educational videos and the ability of determining objects in different depths in a scene, we have proposed a novel object-based video encoding based on "sprite coding" that supports the MPEG-4 Version 1 Main profile in order to transfer distance learning videos across narrow-band transmission links such as the Internet. This paper proposes a multi-layer video object layer generation scheme with fore.-round moving object extraction and background sprite generation using stereo camera property. The foreground object is coded as a video object plane of its related layer, while the background sprite is coded using sprite coding in MPEG-4. We call this coding scheme "sprite mode". Experiments are conducted on video object plane generation and video coding using MPEG-4. We have compared the performance of our sprite mode with MPEG-4 normal mode and have shown that the coding efficiency of the sprite mode is higher than that of the normal mode at the same objective image quality when the foreground ratio is around 30%.

关键词： object-based video coding Distance Learning Stereo Cameras Motion Segmentation MPEG-4

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Exploring Contextual Redundancy in Improving object-based video coding for video Sensor Networks Surveillance

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IEEE TRANSACTIONS ON MULTIMEDIA 2012年第3期14卷 669-682页

作者： Tsai, Tsung-Han Lin, Chung-Yuan Natl Cent Univ Dept Elect Engn Jhongli 3201 Taoyuan Taiwan

In recent years, intelligent video surveillance attempts to provide content analysis tools to understand and predict the actions via video sensor networks (VSN) for automated wide-area surveillance. In this emerging network, visual object data is transmitted through different devices to adapt to the needs of the specific content analysis task. Therefore, they raise a new challenge for video delivery: how to efficiently transmit visual object data to various devices such as storage device, content analysis server, and remote client server through the network. object-based video encoder can be used to reduce transmission bandwidth with minor quality loss. However, the involved motion-compensated technique often leads to high computational complexity and consequently increases the cost of VSN. In this paper, contextual redundancy associated with background and foreground objects in a scene is explored. A scene analysis method is proposed to classify macroblocks (MBs) by type of contextual redundancy. The motion search is only performed on the specific type of context of MB which really involves salient motion. To facilitate the encoding by context of MB, an improved object-based coding architecture, namely dual-closed-loop encoder, is derived. It encodes the classified context of MB in an operational rate-distortion-optimized sense. The experimental results show that the proposed coding framework can achieve higher coding efficiency than MPEG-4 coding and related object-based coding approaches, while significantly reducing coding complexity.

关键词： Contextual redundancy coding intelligent video surveillance object-based video coding operational rate-distortion theory visual sensor network

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Hybrid model-and-object-based real-time conversational video coding

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SIGNAL PROCESSING-IMAGE COMMUNICATION 2015年 35卷 9-19页

作者： Li, Yang Tao, Xiaoming Lu, Jianhua Tsinghua Univ Dept Elect Engn Beijing 100084 Peoples R China

Bandwidth-constrained real-time conversational video communications (such as mobile teleconferencing) require video codecs with good rate-distortion characteristics at low bit-rates and modest computational complexity. While target-specific object-based and model-based coding methods have been proposed for low bit-rate conversational video coding, difficulties in generalization and high computational complexity hinder their practical utilization. In this paper, we propose a low bit-rate coding method for typical conversational video by combining two-dimensional model-based coding of face regions and object-based coding of non-face head-shoulder regions, achieving high-quality face reconstruction and low overall bit-rate with real-time encoding capability. Experiments on typical conversational test sequences confirm that, compared to other conversational video codecs, our model-and-object-based coding method offers superior rate-distortion performance at low bit-rates. (C) 2015 Elsevier B.V. All rights reserved.

关键词： Model-based video coding object-based video coding Face mogdeling

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object-based texture coding of moving video in MPEG-4

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IEEE TRANSACTIONS ON CIRCUITS AND SYSTEMS FOR video TECHNOLOGY 1999年第1期9卷 5-15页

作者： Kaup, A Siemens Corp Technol Networks & Video Commun D-81730 Munich Germany

This paper describes some of the most promising segment-based coding techniques which have been investigated in the course of the MPEG-4 standardization process. Padding methods aim at extending arbitrarily shaped image segments to a regular block grid such that common hybrid block-based coding techniques can be applied. A simple and efficient padding technique employing low-pass extrapolation is outlined which yields a signal extension with high energy concentration in the low-frequency area, Simulations indicate that this method is well suited for block-based video coding, and clearly outperforms other low-complexity extrapolation methods with respect to coding efficiency. In contrast to padding techniques, shape-adaptive methods take advantage of the shape information available at the decoder side. A well-known representative of this class is the SA-DCT. However, having been primarily designed for intraframe coding, it is shown that the transform is suboptimal when applied to interframe coding. Using a suitable covariance model, it is demonstrated that a rescaled, orthonormalized transform much closer approximates the optimal shape-adaptive eigentransform of motion-compensated frame difference images. Rate distortion curves verify that orthonormalization improves coding efficiency in interframe coding by up to 2 dB while not adding to complexity. In a comparison, it is finally shown that extrapolation and SA-DCT perform very closely in the case of low data rates, while there is a clear advantage for the shape-adaptive transform in the case of high-quality video coding.

关键词： coding of motion compensated prediction images low-pass extrapolation MPEG-4 object-based video coding shape-adaptive transforms

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Low bit-rate object-based multi-view video coding using MVC

Low bit-rate object-based multi-view video coding using MVC

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1st International Conference on 3DTV

作者： Krutz, Andreas Droese, Michael Kunter, Matthias Mandal, Mrinal Frater, Michael Sikora, Thomas TU Berlin Commun Syst Grp Berlin Germany Univ Alberta Edmonton AB Canada Univ New South Wales Canberra ACT Australia

ISBN: (纸本)9781424407217

Work is currently underway to develop a new multi-view video coding (MVC) standard, based on the recent H.264/AVC standard. Recent work has shown, however, that object-based video coding can provide higher performance than H.264, especially at low bit rates and in sequences containing rotating camera motion and moving objects in the foreground. In this paper, we propose an object-based extension to MVC, in which sequences are segmented into foreground and background objects, with each object coded using H.264/AVC for single-view sequences and MVC for multi-view sequences. Experimental results show that the object-based approach significantly outperforms the basic MVC at low bit rates.

关键词： object-based video coding sprite coding multiview video H.264/AVC

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Shape-adaptive DCT with block-based DC separation and ΔDC correction

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IEEE TRANSACTIONS ON CIRCUITS AND SYSTEMS FOR video TECHNOLOGY 1998年第3期8卷 237-242页

作者： Kauff, P Schuur, K Heinrich Hertz Inst Commun Technol Image Proc Dept D-10587 Berlin Germany

This paper refers to a shape-adaptive DCT algorithm (SA-DCT) originally proposed by Sikora and Makai in 1995, The SA-DCT has been developed in the framework of the ongoing MPEG-4 standardization phase of ISO/IEC, and has recently been included in the video verification model of MPEG-4. In this context, the focus of the present paper is to emphasize a systematic performance limitation of conventional SA-DCT, and to propose an extended version (Delta DC-SA-DCT) which avoids this restriction in general. This modification considerably improves the efficiency of SA-DCT, and can easily be implemented in existing SA-DCT tools.

关键词： discrete cosine transform MPEG-4 object-based video coding region-based video coding SA-DCT segmented

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Joint Rate Control Algorithm for Low-Delay MPEG-4 object-based video Encoding

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IEEE TRANSACTIONS ON CIRCUITS AND SYSTEMS FOR video TECHNOLOGY 2009年第9期19卷 1274-1288页

作者： Nunes, Paulo Pereira, Fernando Inst Telecommun Inst Super Ciencias Trabalho & Empresa P-1649026 Lisbon Portugal Inst Telecommun IST Dept Elect & Comp Engn P-1049001 Lisbon Portugal

This paper proposes an improved rate control algorithm for jointly encoding multiple arbitrarily shaped video objects in the context of low-delay MPEG-4 compliant video coding. The algorithm provides adequate mechanisms for dealing with deviations between the ideal and the actual behavior of video scene encoders, notably: 1) compensation mechanisms (e. g., rate control decisions) that are able to track these deviations and compensate them to allow a stable and efficient operation of the encoder, and 2) adaptation mechanisms (e. g., estimation of model parameters) that are able to instantaneously represent the actual behavior of the encoder and its rate controller. The proposed solution efficiently allocates the available resources, i.e., target bit rate and bitstream buffer space, aiming at maximizing the average scene quality and minimizing quality fluctuations along time and among the various video objects. The results show that this solution outperforms the usual reference solutions, notably those specified in the rate control informative annex of the MPEG-4 visual standard.

关键词： MPEG-4 video multiple video object rate control object-based video coding

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A contour-based approach to binary shape coding using a multiple grid chain code

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SIGNAL PROCESSING-IMAGE COMMUNICATION 2000年第7-8期15卷 585-599页

作者： Nunes, P Marqués, F Pereira, F Gasull, A Inst Super Tecn Inst Telecomun P-1049001 Lisbon Portugal Univ Politecn Catalunya ES-08034 Barcelona Spain

This paper presents a contour-based approach to efficiently code binary shape information in the context of object-based video coding. This approach meets some of the most important requirements identified for the MPEG-4 standard, notably efficient coding and low delay. The proposed methods support both object-based lossless and quasi-lossless coding modes. For the cases where low delay is a primary requirement, a macroblock-based coding mode is proposed which can take advantage of inter-frame coding to improve the coding efficiency. The approach presented here relies on a grid different from that used for the pixels to represent the shape - the hexagonal grid - which simplifies the task of contour coding. Using this grid, an approach based on a differential chain code (DCC) is proposed for the lossless mode while, for the quasi-lossless case, an approach based on the multiple grid chain code (MGCC) principle is proposed. The MGCC combines both contour simplification and contour prediction to reduce the number of bits needed to code the shapes. Results for alpha plane coding of MPEG-4 video test sequences are presented in order to illustrate the performance of the several modes of operation, and a comparison is made with the shape-coding tool chosen by MPEG-4. (C) 2000 Elsevier Science B.V. All rights reserved.

关键词： shape coding contour coding hexagonal grid multiple grid chain code motion estimation/compensation object-based video coding

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Improvement of region-based motion estimation by considering uncovered regions

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SIGNAL PROCESSING-IMAGE COMMUNICATION 1999年第10期14卷 841-849页

作者： Wang, DM Commun Res Ctr Ottawa ON K2H 8S2 Canada

In natural video sequences, object movement causes regions to be covered or uncovered. Conventional algorithms for region-based motion estimation do not take uncovered regions into full account. Uncovered regions seriously decrease the accuracy of motion estimation. This paper presents an algorithm for increasing the motion estimation accuracy. This algorithm detects uncovered regions and uses them to improve image segmentation and motion estimation. Experimental results show that the presented algorithm is effective in reducing the displaced frame difference, without introducing any extra information for coding applications. (C) 1999 Elsevier Science B.V. All rights reserved.

关键词： motion estimation video coding object-based video coding image segmentation

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Shape-Direction-Adaptive Lifting-based Discrete Wavelet Transform for Arbitrarily Shaped Segments in Image Compression

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IEICE TRANSACTIONS ON INFORMATION AND SYSTEMS 2008年第10期E91D卷 2467-2476页

作者： Lin, Sheng-Fuu Su, Chien-Kun Natl Chiao Tung Univ Dept Elect & Control Engn Hsinchu Taiwan Chung Hua Univ Dept Elect Engn Hsinchu Taiwan

In this paper, a new lifting-based shape-direction-adaptive discrete wavelet transform (SDA-DWT) which can be used for arbitrarily shaped segments is proposed. The SDA-DWT contains three major techniques;the lifting-based DWT, the adaptive directional technique, and the concept of object-based compression in MPEG-4. With SDA-DWT, the number of transformed coefficients is equal to the number of pixels in the arbitrarily shaped segment image, and the spatial correlation across sub-bands is well preserved. SDA-DWT also can locally adapt its filtering directions according to the texture orientations to improve eneryg compaction for images containing non-horizontal or non-vertical edge textures. SDA-DWT can be applied to any application that is wavelet based and the lifing technique provides much flexibility for hardware implementation. Experimental results show that, for still object images with rich orientation textures. SDA-DWT outperforms SA-DWT up to 5.88 dB in PSNR under 2.15-bpp (bit/onject pixel) condition, and reduces the bit-budget up tio 14.0%.

关键词： compression textures set-partitioning embedded block coder (SPECK) object-based video coding shape-direction-adaptive DWT (SDA-DWT)

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