ISO／IEC MPEG—2先进音频编码（二）

ＩＳＯ／ＩＥＣＭＰＥＧ－２先进音频编码（二）３滤波器组滤波器组是ＭＰＥＧ－２ＡＡＣ系统的一个重要组成部分。在编码器中，它把输入端的时域信号转变成系统内部的时间－－频率表示形式。在解码器中，这个过程恰恰相反。在编码器中，使用一个正向的ＭＤＣＴ进行变换，...     

DCT图像处理电路的设计及实现

文章以离散余弦变换的快速蝶形算法为基础，给出了ＤＣＴ硬件系统的设计原理，该硬件系统可实现图像数字信号的实时ＤＣＴ编码，在通信中，可提高系统的抗干扰性数字通信的效率，是进行图像信号的帧间编码和运动补偿编码的基础。     

基于MPEG-2的3DTV视频编码方案的研究

论证了在于ＭＰＥＧ－２的３ＤＴＶ视频压缩编码方案,以实现３ＤＴＶ视频信号的高效传输和存储,并兼容目前的２ＤＴＶ系统。实验方案采用分层编码结构,结合视差补偿预测和运动补偿预测,以ＭＰＥＧ－２时域分级模型实现。实验表明该方案能高质量地有效压缩３ＤＴＶ视频信号。     

静像数据压缩及其标准JPEG（下）

静像数据压缩及其标准ＪＰＥＧ（下）曾国良，丁宗豪七、离散余弦变换ＤＣＴ图２中方框５的作用是将“二维”空间的图像数据用离散余弦变换ＤＣＴ公式变换到二维频域成为二维频率系数。在叙述二维ＤＣＴ公式以前，在此补充一些基本知识。我们知道离散傅氏变换ＤＦＴ及其快...     

一种快速计算DCT的递归算法及其硬件实现

给出了一种快速计算离散余弦变换的递归算法结构。该结构给出了用两个２＾Ｎ－１点ＤＣＴ去代替２＾ 蝶ＣＴ，在此基础上，提出了一种简单实用的用开关控制的ＤＣＴ／ＩＤＣＴ相结合的实现结构，在该 ，仅有正系数的乘法运算和基本的蝶形运算。     

三维小波多分等级树视频压缩编码

提出了基于三维小波多发等级树视频压缩编码方法。通过将原始图象序列进行帧分组,并对每个图象帧组在时间、水平和垂直三维空间上进行小波变换。然后,对变换域的各个空间－时间频率了带按照其方向的不同。构成多个小波等级树,并对每个等级树分别进行ＳＰＩＨＴ编码算法。仿真实验表明了该方法的有效性。     

DC3T的若干性质

本文证明了一种非正交离散余弦变换－ＤＣ３Ｔ具有与经典ＤＣＴ相同的残余相关和更高的变换编码增益，分析了它的熵压缩和能量压缩性质，给出计算复杂度和递推算法，结果表明ＤＣ３Ｔ比ＤＣＴ更适合于图像数据压缩。     

高性能三维小波视频编码方法

讨论并实现了基于３Ｄ－ＳＰＩＨＴ算法的三维小波视频编码方法。该方法建立在真三维小波分解基础上，通过定义一种新的时空方向树结构，实现了静止图像ＳＰＩＨＴ算法的三维扩展。该方法不涉及运动估计，具有较低的计算负荷和时间延迟，所产生的视频流是完全嵌入的。实验结果表明该方法能够快速地、高质量地压缩视频图像，是一种很有潜力的视频编码方法。     

MPEG—2视频IDCT的VHDL描述与验证

反离散余弦变换是ＭＰＥＧ－２中恢复帧内编码系数或差分系数的重要手段。３设计了用于ＭＰＥＧ－２ＭＰ＠ＭＬ视频解码ＶＬＳＩ的ＩＤＣＴ电路结构,采用了ＶＨＤＬ进行描述并通过模拟和验证。这里采用了全硬件实现的方法,并针对性地提出相应的硬件电路结构设计,减少了电路规模以适应ＭＰＥＧ－２ＭＰ＠ＭＬ视频量大,处理复杂的特点,达到实进解码的目的。     

基于双正交小波变换的图像压缩编码

提出了一种基于双正交小波分解的静态图像压缩编码方法,将图像作３次小波分解后,对低频变换系数作ＤＰＣＭ编码,对高频变换系数采用游程编码。实验证明这是一种比较有效的编码方法。     

VIDEO CODING SCHEME FOR ATM NETWORKS

A new variable bit rate layered coding scheme based on subband coding is given in this paper. It can make full use of the merits of ATM transmission, as well as compensation for the quality degradation caused by cell loss, which is an inherent problem of ATM networks, and thus a stable, high quality video transmission is achieved. This paper presents the coding scheme, cell construction and simulation results.     

Packet video and its integration into the network architecture

Packet video is investigated from a systems point of view. The most important issues relating to its transmission are identified and studied in the context of a layered network architecture model, leading to a better understanding of the interactions between network and signal handling. The functions at a particular layer can thereby be made less dependent on network implementation and signal format. In the layered network model, the higher layers provide format conversion, hierarchical source coding, error recovery, resynchronization, cost/quality arbitration, session setup and tear-down, packetization, and multiplexing. Provisions from the network layers pertain mainly to real-time transmission. Special consideration is given to hierarchical source coding, error recovery, statistical behavior, and timing aspects. Simulation results indicating practical solutions to some of the issues raised are presented for a hierarchical packet-video subband coding system     

DRA分层音频编码技术

提出了一种与DRA编码算法兼容的分层音频编码算法,其中环绕声分层编码采用了声道分类方式,而单声道/立体声分层编码则以残差再编码作为增强层的框架。分析和测试结果表明该DRA分层编码算法能够提供较好的声音质量,可作为信源编码与信道编码和分层调制技术完美结合应用于我国数字音频广播。     

An Efficient Time‐Frequency Representation for Parametric‐Based Audio Object Coding

Object‐based audio coding can provide new music applications with interactivity. To efficiently compress a lot of target audio objects, a subband‐based parametric coding scheme has been adopted for MPEG spatial audio object coding. In this letter, the time‐frequency (T/F) subband analysis structure is investigated. A reconfigured T/F structure is also proposed to enhance the generating performance of sound scenes such as ‘karaoke’ and ‘solo’ play in interactive music scenarios. From the experimental results, it was confirmed that the proposed scheme remarkably improves the SNR and sound quality.     

小波变换结合子带编码的Internet图像传输的计算机模拟

尽管Internet带宽巨大，但网络的信息量、用户数量更是庞大的，其拥塞情况是随机的。图像信号在Internet上根据网络拥塞情况进行分层传输与接收是一件有意义的研究工作。当网络处于正常状态时，实时传输高清晰度图像，当网络拥塞情况较严重时，主动丢弃增强层信号仅恢复基本层图像信号。本文从三个方面探讨了小波变换结合子带编码的Internet图像传输的计算机模拟，首先分别介绍小波变换、子带编码的各自特点，接着介绍Internet图像传输的特点，最后给出计算机模拟的实验。     

图像的空间可分级压缩编码及其码率分配

为了能使图像压缩编码算法同时具有较高的压缩率和良好的压缩性能,分析了SPIHT算法,在相同压缩效率的情况下,将其进一步改进,使之具有空间可分级性。在编码过程中,单个像素的相关信息按其所在的分辨率层输出到基础层或增强层码流中,而对于集合的测试信息按其最高层像素所在的分辨率层以较大的概率输出到相应的码流中。这样,虽然低频子带与高频子带相关联而编码,但实验结果显示与低频子带单独编码的性能非常接近。同时给出了一种基础层和增强层间的码率分配方案。实际结果显示：随码率的增大,基础层所占的比率越来越低;对包含边缘较多的图像,其基础层码率所占的比率也较低。     

A layered coding system for very low bit rate video coding

Known coding techniques for transmitting moving images at very low bit rates are explained by the source models on which these coding techniques are based. It is shown that with motion-compensated hybrid coding, object-based analysis-synthesis coding, knowledge-based coding and semantic coding, there is a consistent development of source models. In consequence these coding techniques can be combined in a layered coding system. From experimental results obtained for object-based analysis-synthesis, coding estimates for the coding efficiency of such a layered coding system are derived using head and shoulder video telephone test sequences. It is shown that an additional compression factor of about 3 can be expected with such a complex layered coding system, when compared to block-based hybrid coding.     

图像分层编码技术的分析与设计

无线移动通信信道是时变信道,特性复杂、恶劣,严重影响数字图像信号传输的可靠性。图像分层编码是一种很灵活的编码方式,减轻了因环境变化出现的接收图像质量的剧烈变化,使得图像传输具有良好的鲁棒性和带宽的自适应性,可以有效地解决带宽受限时的图像传输问题。主要介绍了分层编码层数选取、基本层和增强层的码率分配问题,分析了影响这些问题的主要因素,并提出一种基于码率失真理论的增强层码率分配方法。     

甚低比特率小波子带语音压缩编码

本文将谐波压扩和子带编码要结合,设计了一个完整的语音编、解码系统、在这个系统中,我们采用正交小波和双正交小波构造了两组用于子带编、解码的滤波器组,使对其子带的划分与人耳对语音的分辨特性相一致,并且在不同的子带早设计了不同量的量化方案,最后使得该系统对语音有极高的压缩比,同时能保持良好的客观恢复信噪比和主观重建质量。     

Optimization of layered multicast with network coding and genetic algorithm

This article studies the problem of constructing optimal layered multicast with network coding for heterogeneous networks.Based on the flexibility of layered source coding, a global-favorable optimization scheme is proposed, which maximizes the aggregate throughput of heterogeneous sink nodes for layered multicast with network coding by determining the optimal bit rates of the layers. To solve this global-favorable optimization scheme, especially in the large-scale heterogeneous networks, a new problem-specific genetic algorithm (GA) is further proposed. It not only searches efficiently for the optimal allocation of layer bit rates, but also guarantees the validity of candidate solutions in the whole evolutionary process. Simulation results demonstrate that this new GA-based optimization scheme could obtain efficiently the optimal or satisfactorily near-optimal bit rates for layered multicast with network coding, even in the large-scale heterogeneous networks.