ISSN:0899-9457    

DOI:10.1002/ima.1850050402

出版商:John Wiley&Sons, Inc.    

年代:1994

数据来源: WILEY

摘要:

AbstractThis article outlines the evolution of the Grand Alliance (GA) highdefinition television (HDTV) standard from its divided beginnings among several systems to its final state as the proposed standard for HDTV transmission in the United Stales today. Earlier video compression standards are briefly described, and their influence on the first four all‐digital HDTV proposals is demonstrated. The salient features of each proposed video compression system are high‐lighted, and the more recent MPEG‐2 compression standard is introduced. MPEG‐2 was adopted as the basis for video compression by the GA, a group of the former HDTV competitiors. The formation of the GA is described, and the work of its Video Compression Specialists Group on evaluating modifications to MPEG‐2 is reviewed.©1994 John Wil

ISSN:0899-9457    

DOI:10.1002/ima.1850050403

出版商:John Wiley&Sons, Inc.    

年代:1994

数据来源: WILEY

摘要:

AbstractA high‐definition television (HDTV) video compression encoder is being constructed for use during the standardization process for United States terrestrial broadcast HDTV. The encoder generates an MPEG‐2 main profile/high level compliant bitstream at compressed data rates from 10–80 million bits/second. Both interlaced and progressive image formats in image sizes up to 1080 lines × 1920 pixels per line are supported.©1994 John Wiley&

ISSN:0899-9457    

DOI:10.1002/ima.1850050404

出版商:John Wiley&Sons, Inc.    

年代:1994

数据来源: WILEY

摘要:

AbstractA practical and unique hardware architecture for video bitstream source decoding and video postprocessing of a Moving Pictures Expert Group (MPEG‐2)‐based high‐definition television (HDTV) compressed bitstream has been implemented to impose minimal limitations on the video source coding algorithm. The Grand Alliance (GA) MPEG‐2‐based HDTV codec achieves a high degree of source and channel coding efficiency while preserving the delivery of high‐resoultion picture quality in a variety of video input and output formats in bandwidth‐limited channels. The video source decoder hardware architecture necessary to achieve the data decoding and ensuing video postprocessing poses numerous technologic challenges to the system designer, who must tradeoff minimizing codec constraints with the eventual commercialization of a video decoder for a consumer television receiver product. The powerful and flexible coding algorithm necessary to satisfy the HDTV picture quality and transmission channel bandwidth limitation requirements results in an encoder‐output bitstream that necessitates high throughout decoding. Although the transmitted bitstream is of constant rate due to rate buffering, bistreams internal to the codec are both peaky and bursty. An intelligent distributive parallel processing decoding architecture has been developed to dynamically partition the MPEG‐2 bitstream into a number of decodable subset bitstreams, while placing minimal constraints on the encoding algorithm. This architecture allows for high‐speed, efficient decoding of the bitstream, and can be a prelude to the development of a cost‐effective consumer product. Further architecture refinements can be explored, including i

ISSN:0899-9457    

DOI:10.1002/ima.1850050405

出版商:John Wiley&Sons, Inc.    

年代:1994

数据来源: WILEY

摘要:

AbstractMotion estimation is a vital function of video coders that use motion compensated prediction to exploit the temporal redundancy of video signals. The reference images used in the motion estimation process can be either original images (open‐loop architecture) or reconstructed images (closed‐loop architecture). While the closed‐loop architecture is intuitively superior to the open‐loop architecture, closed‐loop motion estimation is more difficult to implement in a real‐time video encoder. A compromise is to perform open‐loop integer‐pel accurate motion estimation followed by closed‐loop half‐pel accurate estimation. In this article we present a comparative study of the performance of half‐pel closed‐loop versus open‐loop motion estimation for coding of high definition television with the MPEG algorithm. Simulation results indicate that on average, closed‐loop half‐pel accurate motion estimation provides slightly better performance than open‐loop half‐pel accurate estimation. This improvement depends on the bit rate of the coded video biststream. For relatively high bit rates, the closed‐loop implementation often provides no improvement, and sometimes an actual degradation of performance. An analysis of why a closed‐loop implementation does not guarantee a better performance

ISSN:0899-9457    

DOI:10.1002/ima.1850050406

出版商:John Wiley&Sons, Inc.    

年代:1994

数据来源: WILEY

摘要:

AbstractThis article describes the format and functionality of the Grand Alliance transport bistream that is intended for the terrestrial broadcast of digital HDTV in the United States. The article begins with an introduction of the HDTV system selection process within the United States, and proceeds with an overview of the Grand Alliance and a description of the Grand Alliance system architecture. The transport functionality and format is the described in detail. The format is based on the use of a fixed‐length packet structure, with packet headers to support different communications protocol functions. The advantages of the packetization approach are first described. The format choice is shown to take into account several diverse system requirements including flexibility, robustness, scalability, and simple interoperability of the bitstream with other transmission media such as ATM network. Higher‐layer protocol functionality in the format, including the ability to extract programs, and the elements of these programs, including the video, audio, and data components, from a multiplexed bitstream, are described. The details of the packet format and the functionality of the different header fields are presented.©1994 John Wiley&Son

ISSN:0899-9457    

DOI:10.1002/ima.1850050407

出版商:John Wiley&Sons, Inc.    

年代:1994

数据来源: WILEY

摘要:

AbstractThe current proposal for terrestrial broadcasting of HDTV in the United States incorporates a flexible approach toward encoding and transmission. Specifically, the format used to encode an HDTV picture will not be fixed. Instead, a variety of transmission formats will be available, unlike the current (NTSC) system. Furthermore, although a basic set of formats will exist initially, it is possible that this set can change over time, depending on the evolution of relevant technologies. This article will consider various topics related to the current and future transmission formats associated with HDTV systems in the United States. This article discusses the usefulness of allowing multiple transmission formats and describes the formats which will be immediately available for HDTV broadcasting, as agreed upon by the Grand Alliance. The relationship between source formats, transmission formats, and display formats are discussed, with reference to some of the signal processing modules required to convert between formats. Finally, the migration of HDTV to incorporate additional formats is addressed. This report describes a method of achieving this migration in a backward‐compatible manner, so that the basic HDTV receivers will not become obsolete.©1994 John Wiley&Sons

ISSN:0899-9457    

DOI:10.1002/ima.1850050408

出版商:John Wiley&Sons, Inc.    

年代:1994

数据来源: WILEY

摘要:

AbstractVarious high‐definition television (HDTV) and advanced television (ATV) scanning parameter sets have been proposed, including the “Grand Alliance” proposal before the U.S. Federal Communications Commission. However, the American Society of Cinematographers has recommended that the proposed 16:9 aspect ratio should be replaced by a simpler and more pleasing 2:1 aspect ratio. Various proposed and existing formats of interest include 640 × 480, 864 × 648, 1024 × 768, 1152 × 864, and 1280 × 1024 for computer screens, and widescreen formats at or near 2 megapixels. When these formats are analyzed in the context of forming the basis for a suitable hierarchy of scalable resolutions and temporal rates with this new aspect ratio in mind, some significant patterns emerge. Certain fundamental issues in constructing a convenient hierarchy include progressive scanning (no interlace), square pixels (or simple squeezes), and a simple fractional relationship between members of the hierarchy, both temporally and in resolution. There is also a need to exceed 70 Hz in display rate for the wide, bright screens of HDTV/ATV. There is great value in compatibility with computer displays, which exceed 70 Hz with various common resolutions in today's ubiquitous 4:3 aspect ratio. The development of a national and global information infrastructure (NIL/GII) would benefit greatly from such commonality of computer and HDTV/ATV formats. There will be a need for every display to present the richest possible image quality in support of the presentation of text, graphics, and still images, as well as our national and world hertage of high‐resolution films. It will also be necessary to develop guidelines for the composition of images and text by taking into account the common display formats which will be available. This is done by understanding the common “safe area” throughout the variety of existing and future displays, and by considering legibility on each. The best possible architecture for digital HDTV/ATV for the United States and internationally will be needed to support the major NII/GII applications, including health care, library access, education, collaborative and remote work, interactive news, on‐line commerce, and many other uses in addition to entertainment..©1994

ISSN:0899-9457    

DOI:10.1002/ima.1850050409

出版商:John Wiley&Sons, Inc.    

年代:1994

数据来源: WILEY

摘要:

AbstractThe unique combination of processing power, memory capacity, and I/O bandwidth found in the IBM POWER Visualization System (PVS) makes it an ideal tool for high‐end, format and resolution‐independent, digital postproduction applications. From computer graphics rendering to video editing, rotoscoping, and special effects, the versatile nature of this general‐purpose computer allows it to adapt constantly to the specific tasks required during almost any phase of the postproduction process. In this articles, we first examine the hardware architecture of the PVS with specific attention paid to the different subsystems and peripherals which provide the large computational power and bandwidth necessary to do HDTV editing and effects work. Next, we describe the PVS system software layer which enables application level software to fully use all of the capabilities of the hardware. We then explore a novel on‐line, nonlinear editing and effects environment available for the PVS, which allows HDTV resolution material to be digitally edited and processed at full resolution. Finally, we conclude by describing some of the applications of the PVS which allow it to be used in a variety of other ways.©1994 John Wiley

ISSN:0899-9457    

DOI:10.1002/ima.1850050410

出版商:John Wiley&Sons, Inc.    

年代:1994

数据来源: WILEY

摘要:

AbstractThe architecture of CCD sensors and their relationship to digital processing of images requires a re‐examination of traditional analog signal processing conventions. Digital processing now requires different methods of analysis and processing in areas such as frequencv response, noise, and scanning techniques. The purpose of this paper is to encourage researchers and engineers to forget some of the traditional analog practices and have them step up to the future with an open mind.©1994 John Wiley&Sons

ISSN:0899-9457    

DOI:10.1002/ima.1850050411

出版商:John Wiley&Sons, Inc.    

年代:1994

数据来源: WILEY