We present a single-chip, MPEG-2 main profile at main level, audio and video encoder and decoder. It combines a RISC core, a 24-bit DSP, video and audio interface units, and several dedicated processing units. A programmable video interface unit supports multiple modes of pre- and post-processing and on-screen display (OSD). The codec has been implemented using a standard-cell library in 0.18 /spl mu/m CMOS technology.

In this paper we present a single chip MPEG-2, MP@ML, video encoder/decoder. It combines a RISC core and several dedicated processing units organized as a process pipeline. It includes a generic 16-bit host interface and direct interfaces to video modulators and demodulators. It has been implemented using a standard-cell library, in a four-layer metal, 0.35 /spl mu/m CMOS technology. Its small size (less than 3 million transistors) and low implementation cost make it suitable for a wide range of consumer applications.

This paper presents a coded-domain combining technique which can accommodate up to six users for continuous presence multipoint video conferencing. This technique is based on a group-of-block (GOB) video unit in the H.261 video standard. Three important technical issues including frame rate synchronization, combiner delay accumulation, and potential quality degradation at the GOB boundary, are addressed. A frame rate synchronization scheme is proposed for the coded-domain combiner. It is observed that delay accumulation will not occur at the combiner with the proposed multiplexing strategy. Further, simulation results indicate that the output perceptual quality is very comparable even without special motion search handling at the GOB boundary. This implies that the proposed scheme can be applied to standard terminals. Finally, we demonstrate the viability of this software-based coded-domain combiner for continuous-presence multipoint video conferencing with a fully functional experimental prototype built around a low-cost personal computer.

Multi-point ISDN videoconferencing with video bridging in network-based servers represents a viable new network service. The paper presents a detailed technical analysis of a continuous presence video bridge using the H.261 video coding standard. The authors first compare the pros and cons of coded domain versus pel domain video bridges. The architecture and the required operations of a coded domain bridge using H.261 are then investigated. They derive the bounds of the bridge delay and the required buffer size for the implementation of the bridge. The delay and the buffer occupancy of the video bridge depend on the order, complexity, and the bit-distribution of the input video sources. To investigate a typical case, the authors simulate the delay and the buffer occupancy of a video bridge. They also provide a heuristic method to estimate the delay in a typical case. Several techniques are discussed to minimize the bridge delay and the buffer size. Finally, they simulate intra slice coding and show that the delay and the buffer size can be reduced significantly using this technique.>

Multi-point videoconferencing provides the full benefits of teleconference but also incurs more involved technical issues. This paper does a detailed analysis of a continuous presence video bridge using the H.261 video coding standard. We first describe the architecture and the required operations of a coded domain bridge using H.261. We then derive the bounds of the bridge delay and the required buffer size for the implementation of the bridge. The delay and the buffer occupancy of the video bridge depend on the order, complexity, and the bit- distribution of the input video sources. To investigate a typical case, we simulate the delay and the buffer occupancy of a video bridge. We also provide a heuristic method to estimate the delay in a typical case. Several techniques were discussed to minimize the bridge delay and the buffer size. Finally, we simulate an intra slice coding and show that the delay and the buffer size can be reduced significantly using this technique.

An HDTV coding scheme that is capable of achieving high quality below 20 Mb/s is presented. The system employs motion estimation/compensation followed by four-band subband splitting. The band signals are then subject to quantization and coded by an innovative high-order entropy coder. It is shown that this high-order entropy coder generates a bit rate nearly 30% lower than that of run-length/Huffman coding for motion-compensated frame differences. About 15% improvement is observed for the intrafield coded data. To reduce the complexity of the high-order entropy coder for high-speed implementation, two techniques, codebook reduction and nonuniform quantization of conditioning samples, are developed. A method for selecting conditioning samples and their order, based on mutual information between samples, is proposed and shown to outperform several other systematic and intuitive approaches. Simulations show that the new system, at about 20 Mb/s, achieves picture quality comparable to that of a 120-Mb/s six-band intrafield coding system previously investigated.>

The source coding scheme for the experimental research prototype that is currently being designed to demonstrate the digital coding of high-definition television (HDTV) for transport within the proposed broadband integrated services digital network (ISDN) fiber optic network is described. The network interface will be used on a packet-based asynchronous transfer mode (ATM) technology. To maximize coding efficiency, run-length coding and variable word length coding are also incorporated in the system. The scheme uses multiple block-size Hadamard transform coding that can be implemented using a set of two-tap filters in a simple subband structure. In spite of the low hardware complexity, which is of dominant importance in the overall system performance, high coding efficiency is obtained. The major features and advantages of this scheme are outlined.>

An efficient lattice vector quantization design and the associated fast coding algorithm are proposed for high-bit-rate, high-quality data compression applications. The codewords are uniformly distributed and densely packed as 2/sup n/-dimensional lattice points, based on a geometric lattice decomposition technique. The maximum quantization error has been chosen as the design criterion. For high-rate applications, it has the following advantages: (1) simple vector codeword generation; (2) no codewords need to be stored and only predetermined rules are used at encoder and decoder ends; (3) highly regular code structure, so that encoding is done via an inverse tree-search suitable for fast parallel processing, and decoding is done similar to a scalar quantizer; (4) high coding quality capability, viz. the maximum quantization distortion can be prespecified to a desired value and the entire hyper-region is covered uniformly; and (5) dimensionality saving can be easily predicted and it can be achieved using fixed-length codes.>