压缩域内的视频图像处理算法

介绍了一些在压缩域内处理已压缩视频流的算法，主要关注如何对DCT系数直接进行处理的算法，对于带有运动估计的压缩系统(如MPEG视频压缩码)介绍了一些解码算法及相应压缩域内的重构操作，这些算法也应用于视频转码。     

Recursive nearest neighbor search in a sparse and multiscale domain for comparing audio signals

We investigate recursive nearest neighbor search in a sparse domain at the scale of audio signals. Essentially, to approximate the cosine distance between the signals we make pairwise comparisons between the elements of localized sparse models built from large and redundant multiscale dictionaries of time-frequency atoms. Theoretically, error bounds on these approximations provide efficient means for quickly reducing the search space to the nearest neighborhood of a given data; but we demonstrate here that the best bound defined thus far involving a probabilistic assumption does not provide a practical approach for comparing audio signals with respect to this distance measure. Our experiments show, however, that regardless of these non-discriminative bounds, we only need to make a few atom pair comparisons to reveal, e.g., the origin of an excerpted signal, or melodies with similar time-frequency structures.     

一种基于chirp信号的空间域鲁棒性水印算法

选取两个chirp信号作为水印信息,嵌入到图像空间域中与该信号有相同数字特征的像素点处,使用两个嵌入位置矩阵作为算法密钥的同时,还根据chirp信号在分数傅立叶变换域呈现冲激的特征来检测水印信号。仿真实验结果表明,该数字水印算法具有良好的不可见性和安全性,算法不仅能抵抗很强的JPEG压缩、加噪、滤波等常用的信号处理操作,对旋转、平移、剪切等几何攻击也有很强的鲁棒性。     

Power analysis of embedded software: a first step towards softwarepower minimization

Embedded computer systems are characterized by the presence of a dedicated processor and the software that runs on it. Power constraints are increasingly becoming the critical component of the design specification of these systems. At present, however, power analysis tools can only be applied at the lower levels of the design-the circuit or gate level. It is either impractical or impossible to use the lower level tools to estimate the power cost of the software component of the system. This paper describes the first systematic attempt to model this power cost. A power analysis technique is developed that has been applied to two commercial microprocessors-Intel 486DX2 and Fujitsu SPARClite 934. This technique can be employed to evaluate the power cost of embedded software. This can help in verifying if a design meets its specified power constraints. Further, it can also be used to search the design space in software power optimization. Examples with power reduction of up to 40%, obtained by rewriting code using the information provided by the instruction level power model, illustrate the potential of this idea     

伪随机二相码码元选取及信号处理算法研究

相位编码信号是低截获概率雷达信号的主要形式之一,能够提高雷达的生存能力。本文阐述了随机二相码的选取原则,在通过计算机仿真选取了适合条件的一组码元的基础上,对数字正交、频域脉冲压缩、旁瓣抑制滤波器设计等信号处理算法及静止和运动目标情况下旁瓣的抑制效果进行了研究和仿真。仿真结果证明了文中分析的正确性。     

基于均值量化的小波域自同步数字音频水印算法研究

文中提出了一种基于均值量化的小波域自同步数字音频水印算法。该算法是一种盲水印算法,水印提取不需要原始音频信号的参与。算法设计中运用了均值量化的策略,音频信号小波分解后,在低频系数中隐藏水印信息;引入了同步信号的思想,利用同步信号定位水印隐藏位置。实验表明,该算法具有较强的鲁棒性、抗攻击性、抗裁剪性。     

Saliency detection in the compressed domain for adaptive image retargeting

Saliency detection plays important roles in many image processing applications, such as regions of interest extraction and image resizing. Existing saliency detection models are built in the uncompressed domain. Since most images over Internet are typically stored in the compressed domain such as joint photographic experts group (JPEG), we propose a novel saliency detection model in the compressed domain in this paper. The intensity, color, and texture features of the image are extracted from discrete cosine transform (DCT) coefficients in the JPEG bit-stream. Saliency value of each DCT block is obtained based on the Hausdorff distance calculation and feature map fusion. Based on the proposed saliency detection model, we further design an adaptive image retargeting algorithm in the compressed domain. The proposed image retargeting algorithm utilizes multioperator operation comprised of the block-based seam carving and the image scaling to resize images. A new definition of texture homogeneity is given to determine the amount of removal block-based seams. Thanks to the directly derived accurate saliency information from the compressed domain, the proposed image retargeting algorithm effectively preserves the visually important regions for images, efficiently removes the less crucial regions, and therefore significantly outperforms the relevant state-of-the-art algorithms, as demonstrated with the in-depth analysis in the extensive experiments.     

MPEG-4: a multimedia standard for the third millennium. 1

MPEG-4 (formally ISO/IEC international standard 14496) defines a multimedia system for the interoperable communication of complex scenes containing audio, video, synthetic audio and graphics material. In this article, we provide a comprehensive overview of the technical elements of the Moving Pictures Expert Group's MPEG-4 multimedia system specification     

G.722: a new CCITT coding standard for digital transmission ofwideband audio signals

CCITT Study Group XVIII recognized the need for a new international coding standard on high-quality audio to allow interconnection of diverse switching, transmission, and terminal equipment and organized an expert group in 1983 to recommend an appropriate coding technique. A tutorial discussion is provided of the adaptive differential PCM (pulse-code modulation) coding method recommended by the group. The discussion covers the subjective performance tests performed, mode initialization and mode switching, data-speed multiplexing, and communication between narrowband and wideband terminals     

A simple circuit using FETs for fading audio signals in and out exponentially in time

This letter describes a simple fading circuit for low frequencies, using the FET as a control element. The logarithm of the output voltage is a linear function of time. Distortion is considerably reduced through a linearization circuit. The fading process can be interrupted at any moment and the rate of attenuation for each signal is maintained without change for several minutes.     

Surveillance video synopsis in the compressed domain for fast video browsing

The traditional pixel-domain based video analysis methods have taken dominated places for long. However, due to the rapidly increasing volume and resolution of surveillance video, the desirable fast and scalable browsing encounters significant challenges in terms of efficiency and flexibility. Under this circumstance, operating surveillance video in compressed domain has aroused great concern in academy and industry. In order to perform the intelligent video analysis task on the premise of preserving accuracy and controlling complexity, this paper presents a compressed-domain approach for massive surveillance video synopsis generation, labeling and browsing. The main work and achievements include: (1) a compressed-domain scheme is established to condense the compressed surveillance video and record the synopsis results; (2) a background modeling method via the Motion Vector based Local Binary Pattern (MVLBP) is introduced to extract moving objects in an efficient way; (3) an object flags based synopsis labeling method is proposed to represent the object regions as well as their display modes in a flexible way. Experimental results show that the video analysis system based on this framework can provide not only efficient synopsis generation but also flexible scalable or playback browsing.     

CoolMOS CS服务器系列MOSFET:向理想开关迈进

前言 CoolMOS CS系列"超级结"MOSFET器件高压设备的成功是基于1998年英飞凌公司推出的CoolMOS技术.这些器件的优越性能实现了区域导通电阻的大幅度降低.     

Molecular electronics: the first steps towards a new technology

Limitations of classical semiconductor physics motivate the study of information storage and information transfer in molecular structures. Fundamental aspects for the construction of possible future molecular electronic devices are discussed and elementary excitations which can serve as molecular information carriers are studied.     

Adaptive step-size algorithm for the interference canceller in the space-time coded DS-CDMA system

In this letter, we propose an adaptive step-size algorithm for the adaptive interference canceller (AIC) in the space-time coded DS-CDMA system. To improve the performance of the fixed step-size AIC (FS-AIC), the regular adaptive step-size algorithm is extended in complex domain and applied to the joint AIC and ML decoder scheme. Simulation results show that the joint adaptive step-size AIC (AS-AIC) and ML decoder scheme using the proposed algorithm has better performance than not only the conventional ML decoder but also the joint FS-AIC and ML decoder scheme without much increase of the decoding delay and complexity.     

A technique for a substantial reduction of the quantization noise in the direct processing of delta-modulated signals

The quantization noise introduced by the direct arithmetic operations on delta modulated signals can be considerably reduced by a proposed technique. According to this technique, the arithmetic network of a digital filter is clocked at a rate higher than that of the delta modulation encoder. Thus, as it is proved, a considerable reduction of the maximum quantization error can be achieved. A simple network is properly used to restore the filter output rate to that of the delta modulation encoder. The experimental results prove that the output sequence quantization noise can be reduced so much that the remaining noise is very close to that of the input delta modulated signal of the filter.     

A theoretical analysis of a buffer frame size conversion algorithm for audio applications ensuring minimum latency

In implementing digital signal processing (DSP) algorithms for audio real-time applications, one is frequently faced with problems regarding incompatibilities between the hardware buffer length (the internal buffer of a professional sound card) and the software buffer size imposed by the underlying algorithm (due to i.e. multirate or FFT constraints). This mismatch is solved by proper frame size conversion algorithms which inevitably introduce delay. In this context, this paper presents a buffering scheme together with a theoretical proof of the minimum delay property shown by it. Some examples derived from frequently encountered issues in DSP applications are reported.     

一种快速的DCT域MPEG-2到MPEG-1下采样转码技术

文章提出了一种快速的DCT域MPEG-2到MPEG-1准卷积下呆样算法。在转码过程中。头信忠保持不变，且要求将每四个相邻MPEG-2宏块变为一个下采样MPEG-1宏块：用最大最小距离方法确定下采样宏块的运动向量、用简单多数原则确定下采样宏块类型以及用加全平均方案确定下呆样宏块的量化参数。另外，对下采样视频转码失真来源进行了分析。实验结果表明我们提出的转码方案，在同样条件下与级联像素域转码器（TM5）相比，不仅其计算复杂性减少67．6％、PNSR提高0．1dB，而且具有很小的比特控制错误。     

MPEG-4视频验证模型中基于内容的编解码算法

ＭＰＥＧ－４是一个正在制定的编码标准,除了具有 ＭＰＥＧ－１和 ＭＰＥＧ－２标准的基于“帧”的功能以外,ＭＰＥＧ－４视频编码算法还支持多媒体环境中对视频景物内的“物体”进行存取与操纵。文中描述了第四版ＭＰＥＧ－４视频验证模型的结构及其提供的主要编码工具和算法。