Taizo Kinoshita

Variable-bit-rate HDTV codec with ATM-cell-loss compensation

A variable-bit-rate coding algorithm based on motion-adaptive discrete cosine transform (DCT) is investigated for asynchronous transfer mode (ATM) environments in broadband integrated-services digital networks (B-ISDN). The algorithm effectively reduces the bit rate, in particular, for HDTV-picture sources with little motion. Adaptive two-layered coding, an ATM cell matrix for error correction, and a block interleave for error concealment are proposed to keep picture quality high by compensating for ATM cell loss. A feedforward control scheme for variable-length coding (VLC), a multimode quantization that restricts peak bit rate and average bit rate, is also proposed for traffic control. Experimental hardware is shown to reduce the coding bit rate for pictures of HDTV conference applications to peak bit rate of 65-Mb/s and an average bit rate of 10-20-Mb/s in ATM environments. >

Variable-bit-rate HDTV coding algorithm for ATM environments for B-ISDN

ABSTRACT A variable bit-rate HDTV coding algorithm based on motion-adaptive DCT is investigated for ATM environments in B-ISDN. Adaptive 2-layered coding, an ATM cell matrix for error correction, and a block interleave for error concealment are proposedto keep picture quality high by compensating for ATM cell loss. A new VLC and acongestion control scheme that restricts peak-rate and average-rate are also proposedfor traffic control. The proposed algorithm is shown to reduce the coding bit-rate for HDTV conference applications in ATM environments to 10-30 Mb/s. 1. INTRODUCflON HDTV services are expected to provide vivid and realistic image communication in B-ISDN. Recently, many simulation studies and prototype codecs have been reported toprovide HDTV secondary distribution services at bit-rates of 100-160 Mb/s. [1]-[4]However, some applications, for example HDTV conferences, require lower andvariable bit-rate coding algorithms to improve transmission cost and picture quality.Complex and highly efficient coding algorithms may also be able to reduce the bit-rate

Symmetric padding for content-based 2D-DCT coding

Content-based coding, which independently codes the objects included in a picture, has recently attracted considerable attention for its property of enabling object-based editing of still and motion pictures. In content-based coding, it is required to code arbitrarily shaped objects. Therefore, it is necessary to apply 2D-DCT to 8 X 8 blocks that include object boundaries. Padding is a technique that enables condign of such blocks by assigning imaginary values to the pixels that are not included in the object. Additionally, padding prevents the increase of the high frequency DCT coefficients which is caused by the discontinuous object boundary. In this paper, a new padding method named Symmetric Padding, which provides high coding efficiency with a simple copy-and-paste procedure, is proposed. Additionally a content-based 2D-DCT coding method, which changes the padding method and the scanning method according to the features of the object shape, is proposed. Due to the increase of the number of zero DCT coefficients, the proposed method shows better coding performance than conventional method, especially, at high bit rates.

Optical digital transmission of HDTV signals for 'contribution' use

The key technologies for a 1.2 Gb/s HDTV optical digital transmission system for contribution service use are addressed. A wide-dynamic-range optical receiver is described. Attained average received optical power for an error rate of 10/sup -9/ was from -6 dBm to -38 dBm, with an optical dynamic range of 32 dB. This system provides for transmission lengths from a few meters to up to 80 km. It was confirmed that the system developed is available for interconnecting HDTV equipment within a studio and for dispatching HDTV programs from a production site to a postproduction studio. Scrambled-8B1C NRZ line coding was used to keep clock recovery reliable in the receiver. The line-coding circuit satisfies the BSI (bit sequence independent) property and can be easily implemented using commercial high speed ECL devices. >