IEEE Transactions on Circuits and Systems for Video Technology

This paper introduces the concept of warped discrete cosine transform (WDCT) and an image compression algorithm based on the WDCT. The proposed WDCT is a cascade connection of a conventional DCT and all-pass filters whose parameters can be adjusted to provide frequency warping. Because only the first-order all-pass filters are considered, the WDCT can be implemented by a Laguerre network connected... View full abstract»

The video performance benefits of burst-by-burst adaptive modulation are studied, employing a higher-order modulation scheme when the channel is favorable, in order to increase the system's bits per symbol capacity and conversely, invoking a more robust lower order modulation scheme when the channel exhibits inferior channel quality. It is shown that due to the proposed adaptive modem mode switchi... View full abstract»

A new method for speeding up the integer wavelet transforms constructed by the lifting scheme is proposed. The proposed method packs multiple pixels (wavelet coefficients) in a single word; therefore, it can make use of the 32-bit or 64-bit computational capability of modern computers to accomplish multiple addition/subtraction operations in one instruction cycle. As a result, our method can save ... View full abstract»

Shape-adaptive block-based texture coding schemes such as the shape-adaptive discrete cosine transform (SA-DCT) raise the need for an architecture which performs efficiently the transform of variable length N. For an implementation requiring standard DCT and SA-DCT, it is advantageous to have a VLSI architecture which can be configured to compute both schemes. Existing fast algorithms usually cons... View full abstract»

In this paper, we present a high-throughput memory-based VLC decoder with codeword boundary prediction. The required information for prediction is added to the proposed branch models. Based on an efficient scheme, these branch models and the Huffman tree structure are mapped onto memory modules. Taking the prediction information, the decompression scheme can determine the codeword length before th... View full abstract»

The organization of multimedia servers is important in the design of low-cost high-performance multimedia application environments. Considering video services as highly demanding applications in a multimedia environment, we analyze and compare centralized and distributed architectures for multimedia video servers. Comparisons are made in terms of the blocking probability of a video client's reques... View full abstract»

A new system for intraframe coding of video is described. This system combines zerotrees of vectors of wavelet coefficients and the generalized-threshold-replenishment (GTR) technique for adaptive vector quantization (AVQ). A data structure, the vector zerotree (VZT), is introduced to identify trees of insignificant vectors, i.e., those vectors of the wavelet coefficients in a dyadic subband decom... View full abstract»

Despite several efforts aimed at reducing the complexity, block-based motion estimation remains the most computationally demanding stage of video compression algorithms. This is particularly evident when sequences contain large displacements; very large search windows are needed to achieve high-quality coding when such critical conditions occur. This paper presents a new block-motion-estimation al... View full abstract»

The gold-washing (GW) mechanism is an efficient on-line codebook refining technique for adaptive vector quantization (AVQ). However, the mechanism is essentially not suitable for hardware implementation. We propose a hardware-oriented GW-AVQ scheme based on the least-recently-used (LRU) strategy for codevector selection and the block-data-interpolation (BDI) algorithm for vector generation. We als... View full abstract»

We describe a robust codec for the transmission of very low bit-rate video over channels with a variety of errors, including random and bursty bit errors and packet loss. The codec exploits adaptivity to give good performance with a low overhead. By only protecting macroblocks which would otherwise be poorly concealed by the decoder the codec allows adaptive selection of the parts of video to prot... View full abstract»

Improvements in the compression performance can be achieved if the image transform is able to adapt to the shape of the objects present. We propose a new hybrid shape-adaptive orthogonal transform which is based on M-channel subband decomposition and shape-adaptive DCT techniques. The signal extension method for the region-based dyadic wavelet transform is applied to region-based image coding usin... View full abstract»

This paper presents a parallelization methodology for video coding based on the philosophy of hiding as much communications by computation as possible. It models the task/data size, processor cache capacity, and communication contention, through a systematic decomposition and scheduling approach. With the aid of Petri-nets and task graphs for representation and analysis, it employs a triple buffer... View full abstract»

A procedure is described for the segmentation, content-based coding, and visualization of videoconference image sequences. First, image sequence analysis is used to estimate the shape and motion parameters of the person facing the camera. A spatiotemporal filter, taking into account the intensity differences between consequent frames, is applied, in order to separate the moving person from the sta... View full abstract»

A newly derived algorithm called three-dimensional polynomial approximation coding (3DPAC) is being utilized in the applications of wireless video transmission. After combining the spatial and temporal domain, the video data is organized in a cube form, which has the features of processing parallelism and great compression ratio. Such a very low bit-rate video codec is able to support the wireless... View full abstract»

A new technique based on the multilayer perceptron (MLP) neural network is proposed for blocking-artifact removal in block-coded images. The new method is based on the concept of learning-by-examples. The compressed image and its original uncompressed version are used to train the neural networks. In the developed scheme, inter-block slopes of the compressed image are used as input, the difference... View full abstract»

We propose a low bit-rate embedded video coding scheme that utilizes a 3-D extension of the set partitioning in hierarchical trees (SPIHT) algorithm which has proved so successful in still image coding. Three-dimensional spatio-temporal orientation trees coupled with powerful SPIHT sorting and refinement renders 3-D SPIHT video coder so efficient that it provides comparable performance to H.263 ob... View full abstract»