The MPEG-1 video standard, ISO/IEC 11172 Part 2, specifies the syntax and the semantic rules by which bitstreams are generated in the encoder, and arithmetic rules by which pictures are reconstructed in the decoder. T...
详细信息
ISBN:
(纸本)0819414824
The MPEG-1 video standard, ISO/IEC 11172 Part 2, specifies the syntax and the semantic rules by which bitstreams are generated in the encoder, and arithmetic rules by which pictures are reconstructed in the decoder. The actual encoder model is left open to the designer to choose among different cost and quality tradeoffs. An example encoder strategy is described in the informative annex D. A technical report giving a full encoder and decoder implementation expressed in the ANSI C programming language will become the fifth part of the ISO/IEC 11172 document. The encoder is based on a test model shaped by participants of the MPEG committee that produces good picture quality while exercising the full video syntax. The decoder employs full arithmetic accuracy at all stages, and include bitstream conformance checks. Finally, a companion systems codec demonstrates the temporal link between the systems and the video layers. To better serve as a learning tool for novices, the code is optimized for clarity rather than execution speed. In addition to an overview of the program, this paper provides a brief description of the encoder model.
4 X 4 inverse DCTs are computationally twice as efficient as 8 X 8 inverse DCTs. In addition they have less register pressure, making the implementation more efficient for most processors. This extra computational eff...
详细信息
ISBN:
(纸本)0819414824
4 X 4 inverse DCTs are computationally twice as efficient as 8 X 8 inverse DCTs. In addition they have less register pressure, making the implementation more efficient for most processors. This extra computational efficiency places more pressure on improving the other components of the video decompression system. This paper describes a coding scheme for the quantized components which has an efficient decompression algorithm. The implementation of the inverse DCT is examined in detail, including removing all multiplication operations and replacing them with single CPU cycle shift-and-add operations. The data flow through a complete 4 X 4 DCT is described such that the results of intermediate 1 X 4 DCTs are written to and read from memory as efficiently as possible. A set of quantizers for the 4 X 4 DCT are presented which allow the decompression process to use shift-and-add instead of multiply. Efficient DCTs by themselves are not enough: the paper discusses the effects of changing the search area (in particular to being non-square) and shows a coding scheme suitable for fast decompression. It also discusses how to organize the block matching and that good results can be obtained if some pixels are allowed to match worse than the nominal value.
The part 1 of this paper was presented during the 1994 SPIE/IS&T Symposium. A specific hardware executing a proprietary VCS1 algorithm (based on COST211ter Group specifications) was described. This hardware was co...
详细信息
New intelligent adapters, advanced bus architectures, and powerful microprocessors have resulted in a new generation of personalcomputers with true multimedia capabilities. Collaborative applications are the most dem...
详细信息
This paper presents a real time full motion video conferencing system based on the Visual Pattern Image Sequence Coding (VPISC) software codec. The prototype system hardware is comprised of two personalcomputers, two...
详细信息
ISBN:
(纸本)0819417661
This paper presents a real time full motion video conferencing system based on the Visual Pattern Image Sequence Coding (VPISC) software codec. The prototype system hardware is comprised of two personalcomputers, two camcorders, two frame grabbers, and an ethernet connection. The prototype system software has a simple structure. It runs under the Disk Operating System, and includes a user interface, a video I/O interface, an event driven network interface, and a free running or frame synchronous video codec that also acts as the controller for the video and network interfaces. Two video coders have been tested in this system. Simple implementations of Visual Pattern Image Coding and VPISC have both proven to support full motion video conferencing with good visual quality. Future work will concentrate on expanding this prototype to support the motion compensated version of VPISC, as well as encompassing point-to-point modem I/O and multiple network protocols. The application will be ported to multiple hardware platforms and operating systems. The motivation for developing this prototype system is to demonstrate the practicality of software based real time video codecs. Furthermore, software video codecs are not only cheaper, but are more flexible system solutions because they enable different computer platforms to exchange encoded video information without requiring on-board protocol compatible video codex hardware. Software based solutions enable true low cost video conferencing that fits the `open systems' model of interoperability that is so important for building portable hardware and software applications.
This paper will talk about the technologies that have been emerging over the 25 years since the Human Vision and Electronic Imaging conference began that the conference has been a part of, and that have been a part of...
详细信息
ISBN:
(纸本)9780819494245
This paper will talk about the technologies that have been emerging over the 25 years since the Human Vision and Electronic Imaging conference began that the conference has been a part of, and that have been a part of the conference, and will look at those technologies that are emerging today, such as social networks, haptic technologies, and still emerging imaging technologies, and what we might look at for the ***-five years is a long time, and it is not without difficulty that we remember what was emerging in the late 1980s. Yet to be developed: The first commercial digital still camera was not yet on the market, although there were hand held electronic cameras. personalcomputers were not displaying standardized images, and image quality was not something that could be talked about in a standardized fashion, if only because image compressionalgorithms were not standardized yet for several years hence. Even further away were any standards for movie compression standards, there was no personal computer even on the horizon which could display them. What became an emergent technology and filled many sessions later, image comparison and search, was not possible, nor the current emerging technology of social networks- the world wide web was still several years away. Printer technology was still devising dithers and image size manipulations which would consume many years, as would scanning technology, and image quality for both was a major issue for dithers and Fourier *** these humble beginnings to the current moves that are changing computing and the meaning of both electronic devices and human interaction with them, we will see a course through the changing technology that holds some features constant for many years, while others come and go.
暂无评论