H．264／AVC中的CABAC编码技术

CABAC是新一代视频压缩算法标准H.264/AVC中采用的新熵编码技术,使用它可以有效提高编码效率,节约码流。这里介绍了CABAC编码中算术编码理论的原理和内容模型的基本类型,并以运动矢量差值MVD的编码方法为例详细分析了CABAC的编码过程。     

数字指纹的技术分析与模型改进

数字指纹作为数字作品版权保护的一种新型技术,越来越受到人们的重视。文章首先介绍了数字指纹的功能与特征,然后分析了指纹的多种编码方案以及指纹协议的演进过程,最后提出了一种数字指纹的系统模型,该模型可用于一些数字作品的版权保护。     

Exploiting temporal information and adaptive thresholding for fast mode decision in the H264 video coding standard

A new algorithm for fast mode decision in the H264 video coding standard is presented in this paper. The algorithm exploits temporal information and adaptive thresholding and can provide significant computational savings with similar or even better Rate Distortion performance as compared to accepted standard contributions and other techniques found in the literature.     

Error-resilient decoding of context-based adaptive binary arithmetic codes

This paper addresses the problem of error-resilient decoding of bitstreams produced by the CABAC (context-based adaptive binary arithmetic coding) algorithm used in the H.264 video coding standard. The paper describes a maximum a posteriori (MAP) estimation algorithm improving the CABAC decoding performances in the presence of transmission errors. Methods improving the re-synchronization and error detection capabilities of the decoder are then described. A variant of the CABAC algorithm supporting error detection based on a forbidden interval is presented. The performances of the decoding algorithm are first assessed with theoretical sources and by considering different binarization codes. They are compared against those obtained with Exp-Golomb codes and with a transmission chain making use of an error-correcting code. The approach has been integrated in an H.264/MPEG-4 AVC video coder and decoder. The PSNR gains obtained are discussed.     

基于小波变换的视频编码算法分类研究

在视频通信中,视频编码技术不但要有高的编码效率而且其生成的码流要有多种可伸缩性.在此研究领域.涌现出许多新的编码思想和技术,其中基于小波变换的视频编码算法就是很有发晨前景的技术之一.本文对小波变换视频编码算法进行分类研究.对比分析算法各自的优缺点,指出小波视频编码算法的研究方向.     

非线性物理破解神经编码机制

信息在神经系统中以脉冲点序列的形式传输和处理，神经系统如何通过脉冲点序列对所表达的信息进行编码，一直是一个谜．人们曾普遍认为，神经可能通过发放率（单位时间发放脉冲出现的次数）对信息编码，也有人猜测，神经可通过脉冲点序列的时序编码．由于神经发放的随机性，这就使得任何编码机制都面临着被表达信息的确定性与表达该信息的信号的随机性的矛盾．通过神经非线性随机动力学模型，文章作者发现，神经点序列的发放率对点序列的时序信息传输的影响，揭示了神经点序列时序信息在神经非线性传输中的随机共振特征．由此预期，并进一步通过听觉心理物理实验观察到，在一定条件下噪声对听觉的增强作用．从而通过非线性物理揭示了听觉时序编码机制的存在以及在时序编码中随机性噪声的积极作用．     

一种基于OTF稳定性的波前编码相位板优化方法

提出了一种简单的可用于光学系统中子午弧矢方向白光OTF稳定性评价的波前编码相位板参量优化方法.该方法仅以标准偏差来评价OTF在目标景深范围内的稳定性,并且结合自适应模拟退火算法在参量空间内优化得到相位板的最佳参量.使用该方法优化得到的相位板参量,可以大幅度提高光学系统的景深,并且可以获得更为清晰、稳定的成像.对应用波前编码技术前后光学系统的成像性能作了比较,并且考察了优化参量的容差性.     

A novel super-FEC code based on concatenated code for high-speed long-haul optical communication systems

The structures of the novel super forward error correction (Super-FEC) code type based on the concatenated code for high-speed long-haul optical communication systems are studied in this paper. The Reed-Solomon (RS) (255, 239) + Bose-Chaudhuri-Hocguenghem (BCH) (1023, 963) concatenated code is presented after the characteristics of the concatenated code and the two Super-FEC code type presented in ITU-T G.975.1 have theoretically been analyzed, the simulation result shows that this novel code type, compared with the RS (255, 239) + convolutional-self-orthogonal-code (CSOC) (k₀/n₀ = 6/7, J = 8) code in ITU-T G.975.1, has a lower redundancy and better error-correction capabilities, and its net coding gain (NCG) at the third iteration is 0.57 dB more than that of RS (255, 239) + CSOC (k₀/n₀ = 6/7, J = 8) code in ITU-T G.975.1 at the third iteration for the bit error rate (BER) of 10⁻¹². Therefore, the novel code type can better be used in long-haul, larger capacity and higher bit-rate optical communication systems. Furthermore, the design and implementation of the novel concatenated code type are also discussed.     

波前编码系统成像特性的空间域分析

波前编码技术在大幅度地增加光学系统景深的同时,可以抑制各种离焦类型的像差。目前波前编码系统的成像特性分析大多是基于空间频率域的分析,在应用稳定相法导出三次型相位板波前编码系统的点扩展函数近似解析式的基础之上,描述了点扩展函数的边界、带宽与振荡等特性,分析了波前编码系统对离焦、像散、彗差等常见像差的敏感性,从空间域进一步分析了波前编码系统的成像特性。     

海面目标ISAR成像的杂波仿真与抑制

对海面目标进行ISAR成像时,会受到海杂波的影响。文中分析了ISAR成像中海杂波的统计分布模型、时间相关特性和空间相关特性,给出了一种相参杂波的仿真方法,并提出了一种ISAR中的杂波抑制算法。仿真算法利用球不变随机过程产生K分布相参杂波,并通过两次线性变换,使得杂波满足给定的时间和空间相关特性。为抑制ISAR信号中的海杂波,本文应用恒虚警检测技术,在预处理的ISAR像上设定一个适当的门限,以保留散射点信号、滤除杂波。最后,仿真结果证明了该算法的有效性。