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Circuits and Systems for Video Technology, IEEE Transactions on

Issue 7 • Date Jul 2001

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Displaying Results 1 - 10 of 10
  • A generalized architecture for the one-dimensional discrete cosine and sine transforms

    Page(s): 874 - 881
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (188 KB) |  | HTML iconHTML  

    In this paper, we propose a generalized architecture for the 1-D discrete cosine transform (DCT), discrete sine transform (DST), and their inverses based on a general formulation. This architecture provides the flexibility to adaptively select different transform functions through a simple control signal. As compared with other unified architectures for the DCT/DST, the proposed architecture possesses better performance in the hardware cost and the number of I/O channels. The proposed design can be efficiently realized by using the distributed arithmetic approach in the VLSI implementation View full abstract»

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  • Scalable, error-resilient, and high-performance video communications in mobile wireless environments

    Page(s): 833 - 847
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (324 KB)  

    A novel mobile communications system is proposed, which provides not only effective but also efficient video access for mobile users when communicating over low-bandwidth error-prone wireless links. The middleware implemented by a mobile proxy server at the mobile support station is designed for the seamless integration of mobile users with video servers, so the specific details of the underlying protocols and source/channel coding techniques are hidden to both the video server and mobile client. Based on the concept of application-level framing, the application (video codec in our case) plays a significant role in network communications that most of functionalities of the system are implemented as part of the application. As such, at the application layer, adaptive source- and channel-coding techniques are developed to jointly provide the user with the highest possible video quality. For efficient source coding, our high-performance low-complexity video-coding algorithm called a 3-D significance-linked connected component analysis (3D-SLCCA) is chosen. Due to its high robustness against channel-error propagation, 3D-SLCCA is well suited for wireless environments. For error-resilient channel coding, a multilayer transmission error-control mechanism is developed. Since there is no additional requirement imposed on either the mobile client or the video server, mobile users interact with the server in exactly the same way as stationary users. Extensive computer experiments demonstrate the effectiveness of the proposed system View full abstract»

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  • Performance modeling of video-on-demand systems in broadband networks

    Page(s): 848 - 859
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (296 KB)  

    A video-on-demand (VoD) system allows a viewer to choose a video of his choice such as movies, electronic encyclopedia, or educational videos, which is delivered to him real time via a network. This paper is a performance study of a distributed video server system in a fully connected backbone network. Under the assumptions of uniform loading and symmetrical network, analytical models are proposed for two server selection strategies (random and least loaded) and for two reservation schemes (the strict reservation and the residual reservation). The models can be used to determine the call blocking probability and the requirements of network bandwidth given the capacity of video servers. In addition, our models provide a useful tool for VoD operators to design and dimension their systems View full abstract»

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  • Error-resilient coding of 3-D graphic models via adaptive mesh segmentation

    Page(s): 860 - 873
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (324 KB) |  | HTML iconHTML  

    Current coding techniques for 3-D graphic models mainly focus on coding efficiency, which makes them extremely sensitive to channel errors due to the irregular mesh structure. We introduce a new approach for error-resilient coding of arbitrary 3-D graphic models by extending the error-free constructive traversal compression scheme proposed by Li and Kuo (see MPEG-4 Tokyo Meeting, 1998, Contribution Doc. M3324, and Proc. IEEE, vol.86, p.1052-63, 1998). A 3-D mesh of an arbitrary structure is partitioned into pieces of a smaller uniform size with joint boundaries. The size of a piece is determined adaptively based on the channel error rate. The topology and geometry information of each joint boundary and each piece of a connected component is coded independently. The coded topology and first several important bit-planes of the joint-boundary data are protected against channel errors by using the Bose-Chaudhuri-Hocquenghem error-correcting code. At the decoder, each piece is decoded and checked for channel errors. The decoded joint-boundary information is used to perform data recovery and error concealment on the corrupted piece data. All decoded pieces are combined together according to their configuration to reconstruct all connected components of the complete 3-D model. Our experiments demonstrate that the proposed approach has excellent error resiliency at a reasonable bit-rate overhead. The techniques is also capable of incrementally rendering one connected component of the 3-D model at a time View full abstract»

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  • Postprocessing for vector-quantized images based on projection onto hypercubes

    Page(s): 802 - 814
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (348 KB) |  | HTML iconHTML  

    In this paper, in order to reduce blocking artifacts in vector-quantized images, we propose a new postprocessing algorithm, based on the projection onto a subset of quantization constraint set (QCS). The notion behind the projection onto QCS is to prevent the postprocessed data from diverging from QCS, i.e., blurring, which is usually caused by a low-pass filtering operation. First, we theoretically analyze the projection onto QCS, and show that the projection onto a subset of QCS could yield a better performance than the projection onto QCS case. Since the quantizer regions in the vector quantizer (VQ) are arbitrarily shaped unless the VQ has a structural codebook, it is not easy to implement a projector for QCS. In order to simplify the projection, we introduce hypercubes for a subset of QCS, where the hypercubes are the elements of the subset. Hence, the proposed postprocessing algorithm has two steps: linear space-invariant low-pass filtering (or projecting onto smoothness constraint sets) and then projecting onto hypercubes. Simulation results show that the proposed algorithm can reduce blocking artifacts without blurring the edge components, and achieve a 0.5-2.0-dB gain. Furthermore, the contouring effect can also be removed by iteratively applying the proposed postprocessing algorithm, based on the constrained minimization problem View full abstract»

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  • Multiview extensive partition operators for semantic video object extraction

    Page(s): 788 - 801
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (364 KB) |  | HTML iconHTML  

    Occlusion/disocclusion is one of the fundamental problems for semantic video object (SVO) extraction, where pixel-wise accuracy is required. This issue is critical because the degradation in tracking due to object occlusion/disocclusion significantly increases the amount of user interaction required in off-line video editing applications. We present an approach based on the application of an extensive operator on a lattice of partitions, which exploits information from various views of the scene, based on a probabilistic formulation. Our multiview operator builds on the regional application of the maximum a posteriori principle, by integrating a single-view region classification stage with a multiview stage that improves classification for those disoccluded regions labeled as uncertain. Results on several real sequences show that our approach improves the SVO tracking compared to the single-view case and that, as a result, increases the quality of the extracted SVOs and reduces the total amount of user interaction View full abstract»

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  • Constrained bit-rate control for very low bit-rate streaming-video applications

    Page(s): 882 - 889
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (180 KB) |  | HTML iconHTML  

    We propose a low-complexity frame-layer bit-rate control algorithm for very low bit-rate streaming-video applications with causal one-pass processing. Rate control is achieved by jointly adapting the frame rate and quantization step-size. Constraint coding is introduced, which forces the encoder to operate within a subset of operating points on a 2-D grid. The control parameters are also constrained to change in a gradual fashion, allowing bits to be saved in easy scenes so that more bits can be used for difficult scenes. A simple scene-change detector is used to insert intra frames at scene-change boundaries. The proposed algorithm is implemented in H.263 and is compared with the case of fixed control parameters and a conventional off-line bit-rate control based on adapting the quantization step-size. It is shown that the proposed algorithm codes more frames over a given time interval while achieving average PSNR gains over 1 dB and reducing bit-rate fluctuations. Results are confirmed by subjective tests, which show that our bit-rate control consistently provides improved visual quality View full abstract»

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  • Wavelet-based video coder via bit allocation

    Page(s): 815 - 832
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (536 KB) |  | HTML iconHTML  

    We present a video coder based on a bit allocation (BA) scheme for a coding approach where a wavelet-based video compression scheme is used to encode a group of frames (GOF). The proposed new BA method utilizes a Lagrangian multiplier technique to determine the optimal bit rate for each frame of a given GOF in a rate versus weighted distortion sense. The proposed baseline coder sequentially employs the application of the wavelet transform on each frame in the group. In the wavelet domain, an optimal-vector BA (rate-allocation strategy) is being used to distribute the bit budget among the frames. The manipulated frames in each group are quantized and coded using techniques from still-image compression. We describe and demonstrate the performance of the proposed algorithm in wavelet-based coding approaches. The first one, a combination of wavelet still compression and optimal BA (WCBA), is based on frame differences and exploits well the wavelet compression characteristics which keeps, for a given bit budget, the most important features. It does not utilize motion-compensation interpolation or a 3-D wavelet decomposition. In cases where “heavy” motion is detected, we extend WCBA into a combination of wavelet still compression, optimal BA, motion compensation with block matching, and error correction (WCBAM), which uses block matching for motion estimation, while the residual error of the compression is reduced by applying error correction in the wavelet domain to reduce temporal redundancies View full abstract»

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  • A novel low-power full-search block-matching motion-estimation design for H.263+

    Page(s): 890 - 897
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (256 KB) |  | HTML iconHTML  

    In this paper, a low-power full-search block matching (FSBM) motion-estimation design for the ITU-T recommendation H.263+ standard is proposed. New motion-estimation modes in H.263+ can be fully supported by our architecture. Unlike most previously presented motion-estimation chips, this design can deal with 8×8 and 16×16 block size with different searching ranges. Basically, the proposed architecture is composed of an integer pixel unit with 64 processing elements, and a half-pixel unit with interpolation, a control unit, and data registers. In order to minimize power consumption, gated-clock and dual-supply voltages are used. This design has been realized by TSMC 0.6 μm SPTM CMOS technology. The power consumption is 423.8 mW at 60 MHz and the throughput is 36 fps in CIF format View full abstract»

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  • Two-dimensional separable filters for optimal reconstruction of JPEG-coded images

    Page(s): 777 - 787
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (280 KB) |  | HTML iconHTML  

    Transform coding is a technique used worldwide for image coding, and JPEG has become the most common tool for image compression. In a JPEG decoder, the quantized transform coefficient blocks are usually processed using the inverse discrete cosine transform (DCT) in order to reconstruct an approximation of the original image. The direct and inverse DCT pair can be arranged in the form of a perfect reconstruction filter bank, and it can be shown that, in the presence of quantization of the transform coefficients, the perfect reconstruction synthesis is not the best choice. In this paper, we propose a procedure for the design of separable 2-D synthesis filters that minimize the reconstruction error power for transform coders. The procedure is used to design a family of filters which are used in the decoder instead of the inverse DCT. The appropriate reconstruction filters are selected on the basis of the standard quantization information provided in the JPEG bit stream. We show that the proposed decoding method gives some gain with respect to the usual decoder in most cases, Moreover, it only makes use of the standard information provided by a JPEG bit stream View full abstract»

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Aims & Scope

The emphasis is focused on, but not limited to:
1. Video A/D and D/ A
2. Video Compression Techniques and Signal Processing
3. Multi-Dimensional Filters and Transforms
4. High Speed Real-Tune Circuits
5. Multi-Processors Systems—Hardware and Software
6. VLSI Architecture and Implementation for Video Technology 

 

Full Aims & Scope

Meet Our Editors

Editor-in-Chief
Dan Schonfeld
Multimedia Communications Laboratory
ECE Dept. (M/C 154)
University of Illinois at Chicago (UIC)
Chicago, IL 60607-7053
tcsvt-eic@tcad.polito.it

Managing Editor
Jaqueline Zelkowitz
tcsvt@tcad.polito.it