Video compression using mosaic representations

We describe a technique for video compression based on a mosaic image representation obtained by aligning all frames of a video sequence, giving a panoramic view of the scene. We describe two types of mosaics, static and dynamic, which are suited for storage and transmission applications, respectively. In each case, the mosaic construction process aligns the images using a global parametric motion transformation, usually canceling the effect of camera motion on the dominant portion of the scene. The residual motions that are not compensated by the parametric motion are then analyzed for their significance and coded. The mosaic representation exploits large scale spatial and temporal correlations in image sequences. In many applications where there is significant camera motion (e.g., remote surveillance), it performs substantially better than traditional interframe compression methods and offers the potential for very low bit-rate transmission. In storage applications, such as digital libraries and video editing environments, it has the additional benefit of enabling direct access and retrieval of single frames at a time.     

Video compression employing algorithm using temporal blockingstructures

A new video compression algorithm based on a temporal blocking structure, rather than the more conventional spatial blocking structure, is described. This blocking structure forms the basis of an adaptive vector quantisation (VQ) algorithm, the performance of which is then compared with a similar adaptive VQ scheme based on a spatial blocking structure     

非线性编辑系统中的视频压缩技术

在采用压缩方式的非线性编辑系统中，视频质量的好坏取决于视频压缩卡质量和视频压缩技术的选择。目前，M－JPEG，MPEGII和DV这3种视频压缩方式是“非编”主要采用的视频压缩技术，其特点各异，MPEG－2和DV两种格式已有公认的国际标准。介绍了这3种压缩方式的主要特点和应用情况，分析了其在“非编”中应用发展的趋势。     

Video compression using spatiotemporal regularity flow.

We propose a new framework in wavelet video coding to improve the compression rate by exploiting the spatiotemporal regularity of the data. A sequence of images creates a spatiotemporal volume. This volume is said to be regular along the directions in which the pixels vary the least, hence the entropy is the lowest. The wavelet decomposition of regularized data results in a fewer number of significant coefficients, thus yielding a higher compression rate. The directions of regularity of an image sequence depend on both its motion content and spatial structure. We propose the representation of these directions by a 3-D vector field, which we refer to as the spatiotemporal regularity flow (SPREF). SPREF uses splines to approximate the directions of regularity. The compactness of the spline representation results in a low storage overhead for SPREF, which is a desired property in compression applications. Once SPREF directions are known, they can be converted into actual paths along which the data is regular. Directional decomposition of the data along these paths can be further improved by using a special class of wavelet basis called the 3-D orthonormal bandelet basis. SPREF -based video compression not only removes the temporal redundancy, but it also compensates for the spatial redundancy. Our experiments on several standard video sequences demonstrate that the proposed method results in higher compression rates as compared to the standard wavelet based compression.     

基于零树的视频压缩加密联合编码方案

针对可伸缩性视频流的安全性问题，提出了一种与编码相结合的加密方案。该方案以小波变换作为压缩平台，通过在零树生成的过程中对零树符号进行加密来保证视频的安全性，并且采用分级加密来满足不同用户对不同质量服务的需求。实验证明该方案一方面保持了编码的可伸缩性，另一方面提高了视频流的安全性，并且加密处理对压缩效率影响小，适用于网络上的视频流服务。     

Multimedia broadcasting over the Internet. II. Video compression

For pt.I see ibid., (Oct-Dec. 1998). In the first part of our project report, we described a new technique for multimedia broadcasting over the Internet, called IP Simulcast. In this article we introduce a new video compression technique, called XYZ compression, which suits ultra-low bandwidth applications very well     

Video compression with binary tree recursive motion estimation andbinary tree residue coding

Binary tree predictive coding (BTPC) is an efficient general-purpose still-image compression scheme, competitive with JPEG for natural image coding and with GIF for graphics. We report the extension of BTPC to video compression using motion estimation and compensation techniques which are simple, efficient, nonlinear and predictive. The new methods, binary tree recursive motion estimation coding (BTRMEC), and binary tree residue coding (BTRC) exploit the hierarchical structure of BTPC, in the first case giving progressively refined motion estimates for increasing numbers of pels and in the second case providing efficient residue coding. Compression results for BTRMEC and BTBC are compared against conventional block-based motion compensated coding as provided by MPEG. They show that both BTRMEC and BTRC are efficient methods to code video sequences.     

Video compression of coronary angiograms based on discrete wavelet transform with block classification

A new method of video compression for angiographic images has been developed to achieve high compression ratio (~20:1) while eliminating block artifacts which leads to loss of diagnostic accuracy. This method adopts motion picture experts group's (MPEGs) motion compensated prediction to takes advantage of frame to frame correlation. However, in contrast to MPEG, the error images arising from mismatches in the motion estimation are encoded by discrete wavelet transform (DWT) rather than block discrete cosine transform (DCT). Furthermore, the authors developed a classification scheme which label each block in an image as intra, error, or background type and encode it accordingly. This hybrid coding can significantly improve the compression efficiency in certain eases. This method can be generalized for any dynamic image sequences applications sensitive to block artifacts.     

Video compression for lossy packet networks with mode switching and a dual-frame buffer

Video codecs that use motion compensation benefit greatly from the development of algorithms for near-optimal intra/inter mode switching within a rate-distortion framework. A separate development has involved the use of multiple-frame prediction, in which more than one past reference frame is available for motion estimation. In this paper, we show that using a dual-frame buffer (one short-term frame and one long-term frame available for prediction) together with intra/inter mode switching improves the compression performance of the coder. We improve the mode-switching algorithm with the use of half-pel motion vectors. In addition, we investigate the effect of feedback in making more informed and effective mode-switching decisions. Feedback information is used to limit drift errors due to packet losses by synchronizing the long-term frame buffers of both the encoder and the decoder.     

嵌入式USB日益普及

虽然USB技术在台式计算领域的地位已经稳如磬石,但由于其以主机为中心的拓扑结构、软件复杂性以及较高的功率要求,所以在嵌入式设备中的应用一直举步维艰.很多设计师宁愿沿用原来的串行或者分立I/O接口,而不愿触及复杂的USB.但是,业内的一些工作小组最近对USB规范进行了修改,允许使用替代的连接方法,对主机电源要求有所降低,并可选用480Mbps的数据传输速率.这些修改,再加上有数百种现成的廉价外围设备可供使用,使人们对在嵌入式设备中使用USB的兴趣与日俱增.     

Video aggregation: adapting video traffic for transport overbroadband networks by integrating data compression and statisticalmultiplexing

Future broadband integrated services networks based on the asynchronous transfer mode (ATM) technology are expected to carry information from a large variety of different services and applications. This paper investigates video aggregation, a concept that integrates compression and statistical multiplexing of video information for transport over a communication network. We focus on the transmission of a group of video sessions as a bundle, the practical examples of which include entertainment-video broadcast and video-on-demand (VoD). In this situation, the advantage of constant bit-rate (CBR) transport (which facilitates simple network management and operation) and the advantage of variable bit-rate (VBR) video compression (which yields smoother image quality) can be achieved simultaneously. We show that it is better to integrate compression and statistical multiplexing before the bundle of video traffic enters the network than performing them as independent processes. We present experimental results which indicate the advantages of video aggregation in terms of superior image quality and efficient bandwidth usage     

单片GSM电话集成更多模块

Silicon Laboratories今天声称推出第一个完全集成的单片GSM/GPRS手持电话。据Silicon Labs工作人员说,AeroFone Si4905在单片CMOS集成电路上集成了电源管理单元、电池接口和充电电路、数字基带、模拟基带以及一个四波段RF收发器。“这是在单片芯片上放置功能单元的最     

启明星辰让UTM简单化——从防火墙进入UTM时代到UTM进入简单时代

5月18日,国内数十家新闻媒体的记者来到启明星辰公司在北京中关村软件园新建成的启明星辰大厦。在参观了独特而又气势不凡的启明星辰新大厦整体结构之后,两个多月前刚     

Intevac makes the POINT

Following our feature in issue 1, we report on other new technical and product developments from Intevac MBE Equipment Division, Santa Clara, CA, USA. Firstly, we report on the new products: Heated Window Assembly, the Effusion Source Enhacement, POINT system and new substrate holder design and then on successful p-type doping of GaN at Boston University.     

THE CODING GAINS OF MEMORIES

The coding gains including self-gain, mutual-gain and their variations for coding memory are denned, and the formulas for computing the gains are derived. The coding gains, used as the criteria, will be enable us to select an efficient code for memory system design quantitatively. Finally, the numerical results of some examples are analysed and discussed.     

嵘兴,追求服务制胜

如今,每个企业的管理者都面临着这样一个现实:产品差异性愈来愈小,促销手段已经用尽,竞争对手却愈来愈多,而客户的要求又千变万化.在这种情况下,企业只有时刻关注和了解客户的需要,建立完善的客户服务体系,才能在日益激烈的商战中获得持久的竞争优势.嵘兴,这个1994年开始起家的民营企业,为什么能在短短的几年中脱颖而出,成为无线电监测领域软件开发的佼佼者?其实,他们靠的不仅仅是领先的技术,更重要的是他们始终致力于向用户提供优质的服务.前不久,一个偶然的机会,笔者有幸对嵘兴公司提供售后服务的工程部和技术支持部这两个部门有了一些了解.