Error-resilient coding in JPEG-2000 and MPEG-4

The rapid growth of mobile communications and the widespread access to information via the Internet have resulted in a strong demand for robust transmission of compressed image and video data for various multimedia applications and services. The challenge of robust transmission is to protect the compressed image/video data against hostile channel conditions while bringing little impact on bandwidth efficiency. This paper addresses this critical problem and provides an overview of the error-resilient approaches that have been evaluated and inserted into the emerging JPEG-2000 wavelet-based image coding standard. We also review the state-of-the-art techniques adopted in the MPEG-4 standard for robust transmission of video and still texture data. These techniques include resynchronization strategies, data partitioning, reversible VLCs, and header extension codes. The performance of these approaches under various channel conditions is evaluated     

MPEG-4自然视频编码技术

对MPEG－4自然视频编码的关键技术作了详细的分析和阐述。首先介绍MPEG－4频语法结构，并对视频编码的框架概要分析。接着分析了自然视频编码中涉及到的关键技术，包括：VOP的产生；二值和灰度级α平面的编码技术；运动估计和补偿方法；纹理编码；基于对象的时间分级和空间分级；MPEG－4提供的再同步和各种错误掩盖，刷新方法，精 编码技术和零树小波基的静止图像编码技术。指出MPEG－4和MPEG－1，MPEG－2等标准的异同，突出MPEG－4的三个主要特点。最后给出MPEG－4技术在网络视频传输中的应用，并给出测试和分析。     

MPEG-4中视频对象平面的形状编码

首先介绍了MPEG-4中视频对象平面(VOP)形状编码的流程，然后分别介绍了VOP形状编码的各个步骤，最后提出了一种基于H．263的MPEG-4视频编码器简单框架(Simple子Pmfile)的实现方法。     

Error-resilient image and video coding for wireless communicationsystems

Current techniques for coding images and video sources with resilience to channel errors can remove much of the need for complex high-redundancy channel coding and provide a graceful degradation of performance with decreasing channel quality. The main function of these error-resilient techniques is to reduce the propagation of errors within the decoded data. Two main techniques are discussed in detail: the error-resilient entropy code (EREC) and pyramid vector quantisation (PVQ). The paper concludes with a comparison of the relative merits of these systems and areas for further consideration     

Error-resilient scalable compression based on distributed video coding

Distributed Video Coding (DVC) is a new paradigm for video compression based on the information theoretical results of Slepian–Wolf (SW) and Wyner–Ziv (WZ). In this work, a performance analysis of image and video coding schemes based on DVC is presented, addressing temporal, quality and spatial scalability. More specifically, conventional coding is used to obtain a base layer while WZ coding generates the enhancement layers. At the decoder, the base layer is used to construct Side Information (SI) for the DVC decoding process. Initially, we show that the scalable DVC approach is codec-independent, which means that it is independent from the method used to encode the base layer. Moreover, the influence of the base layer quality on the overall performance of the schemes is studied. Finally, evaluation of the proposed schemes is performed in both cases, with and without transmission errors. The simulation results show that scalable DVC has a lower compression efficiency than conventional scalable coding (i.e. scalable video coding and JPEG2000 for video and image, respectively) in error-free conditions. On the other hand, the DVC-based schemes show better error resilience as they outperform conventional scalable coding in error-prone conditions. More specifically, the Rate Distortion (RD) performance of the proposed schemes for image coding is compared with respect to Reed Solomon (RS) protected JPEG2000. While the latter exhibits a cliff effect as its performance dramatically decreases after a certain error rate, the performance of the DVC-based schemes decreases in a steady way with error rate increase.     

基于对象的视频编码方法——MPEG-4

介绍了MPEG－4的各种编码方法，为了支持众多的多媒体应用，MPEG－4不仅保留了现有标准中的一些解决方案，而且致力于一些新功能的研究与定义，MPEG－4视频编码标准支持MPEG－1，MPEG－2中的大多数功能，提供不同视频标准源格式、码率、帧频下矩形图像的有效编码，同时也将支持基于内容的图像编码。     

MPEG-4视频标准及其关键算法

MPEG-4引入了视频对象的概念,有效地支持基于内容的图像编码,对不同的视频源标准格式和不同的视频码率提供有效的编码,以满足众多多媒体的应用需求。本文系统地分析了MPEG-4视频编码算法,对MPEG-4视频标准的关键概念进行了详细的解释。     

MPEG-4精细可扩展性视频编码技术研究

精细可扩展视频编码FGS（Fine Granular Scalable Coding）是MPEG-4标准中视频化框架的关键性编码技术。它随着Intemet的飞速发展而产生并很好地适宜了网络的高度异质特性，具有良好的鲁棒性。     

Error concealment for shape in MPEG-4 object-based video coding.

In asynchronus transfer mode networks, cell loss or channel errors can cause data to be dropped in the channel. When digital images/videos are transmitted over these networks, one must be able to reconstruct the missing data so that the impact of the errors is minimized. In this paper, we present an error-concealment technique for shape in MPEG-4 object-based video coding. This method, which is based on using global motion estimation and compensation techniques for boundary recovery, consists of three steps: (1) boundary extraction from shape; (2) boundary patching using global motion compensation; and (3) boundary filling to reconstruct the shape of the damaged video object planes. Global motion parameters are inserted as part of the USER_DATA field in the compressed stream and are utilized in reconstructing the damaged boundaries of compressed video object planes.     

MPEG-4标准视频编码器在Blackfin 21535上的实现

介绍了基于Blackfin21535的MPEG-4视频编码和解码的硬件及软件环境，并提出了基于该环境下的一种软件优化设计方法，为有效解决传输数据瓶颈问题提供新思路。     

基于DSP的MPEG-4视频编码软件优化设计

采用TMS320C6201 DSP芯片实现了实时的MPEG—4视频编码器，在扼要介绍了MPEG—4算法原理的基础上，探讨了软件优化的技术关键——代码优化方法，并给出了实验结果。     

Two-layer hierarchical coding for MPEG-2 video

A two-layer scheme for MPEG-2 video that uses adaptive data-partitioning (ADP) is presented. The slice structure of the upper layer and a new synchronisation procedure between the layers are defined. The experimental results prove the effectiveness of the two-layer model. Particularly for increasing values of cell loss probability     

Context-based entropy coding in AVS video coding standard

In this paper, two context-based entropy coding schemes for AVS Part-2 video coding standard are presented. One is Context-based 2D Variable Length Coding (C2DVLC) as a low complexity entropy coding scheme for AVS Part-2 Jizhun profile. C2DVLC uses multiple 2D-VLC tables to exploit the statistical features of DCT coefficients for higher coding efficiency. Exponential–Golomb codes are applied in C2DVLC to code the pairs of the run-length of zero coefficients and the non-zero coefficients for lower storage requirement. The other is Context-based Binary Arithmetic Coding (CBAC) as an enhanced entropy coding scheme for AVS Part-2 Jiaqiang profile. CBAC utilizes all previously coded coefficient magnitudes in a DCT block for context modeling. This enables adaptive arithmetic coding to exploit the redundancy of the high-order Markov process in DCT domain with a few contexts. In addition, a context weighting technique is used to further improve CBAC's coding efficiency. Moreover, CBAC is designed to be compatible to C2DVLC in coding elements which simplifies the implementations. The experimental results demonstrate that both C2DVLC and CBAC can achieve comparable or even slightly higher coding performance when compared to Context-Adaptive Variable Length Coding (CAVLC) in H.264/AVC baseline profile and Context-Based Adaptive Binary Arithmetic Coding (CABAC) in H.264/AVC main profile respectively.     

Error-resilient SPIHT image coding

The authors develop an efficient error-resilient scheme for the set partitioning in hierarchical trees (SPIHT) technique, one of the most successful image compression algorithms. By partitioning the coded data sequence and adding appropriate side information, the proposed algorithm provides significantly better PSNR performance over noisy channels with a minimal increase in the coding complexity     

Joint video coding of MPEG-2 video programs for digitalbroadcasting services

In digital broadcasting services such as digital satellite TV, cable TV, and digital terrestrial TV, several video programs are compressed by MPEG-2 and then simultaneously transmitted over a conventional CBR (constant bit rate) broadcasting channel. In this environment, the picture quality of the aggregated video programs should be kept as equal as possible to provide fair video services for all the viewers. We propose a joint video coding scheme for ensuring that the picture quality of all the programs are nearly the same. This objective is achieved by simultaneously controlling the video encoders to generate the VBR (variable bit rate) compressed video streams. This paper contributes in two ways. First, we propose a rate-distortion estimation method for MPEG-2 video, which enables us to predict the amount of bits and the distortion generated from an encoded picture at a given quantization step size and vice versa. The most attractive features of the proposed estimation method are its accuracy and a computational complexity low enough to be applied to real-time video coding applications. Second, this paper presents an efficient and accurate joint video coding scheme using the rate-distortion estimation results. The experimental results show that our coding scheme gives a higher and more stable picture quality and a more efficient channel utilization than an independent coding scheme that encodes each program independently     

MPEG-4 natural audio coding

MPEG-4 audio represents a new kind of audio coding standard. Unlike its predecessors, MPEG-1 and MPEG-2 high-quality audio coding, and unlike the speech coding standards which have been completed by the ITU-T, it describes not a single or small set of highly efficient compression schemes but a complete toolbox to do everything from low bit-rate speech coding to high-quality audio coding or music synthesis. The natural coding part within MPEG-4 audio describes traditional type speech and high-quality audio coding algorithms and their combination to enable new functionalities like scalability (hierarchical coding) across the boundaries of coding algorithms. This paper gives an overview of the basic algorithms and how they can be combined.     

MPEG-4 high-efficiency AAC coding

The name MPEG-4 high-efficiency AAC (HE-AAC) refers to a family of recent audio coders that was developed by the International Organization for Standardization/International Electrotechnical Commission (ISO/IEC) Moving Picture Experts Group (MPEG) by subsequent extension of the established Advanced Audio Coding (AAC) architecture. These algorithmic extensions facilitate a significant increase in coding efficiency relative to previous standards and other known systems. Thus, they provide a representation for generic audio/music signals that offers high audio quality also to applications limited in transmission bandwidth or storage capacity, such as digital audio broadcasting and wireless music access for cellular phones. This article presents a compact overview of the evolution, technology, and performance of the MPEG-4 HE-AAC coding family.     

Performance evaluation of MPEG-2 video coding for HDTV

We examine the subjective and objective performance of HDTV coded using the MPEG-2 video coding standard. Tests were conducted on seven HDTV sequences selected to cover a broad range of program materials in terms of scene content, complexity, motion speed and direction. The selected material was digitized in a 4:2:2 format with HDTV resolution and coded using the MPEG-2 main profile/high level syntax. Formal subjective assessment was performed by non-expert viewers on the sequences coded at a bit rate of 18 Mbits/s. Since MPEG-2 allows a great flexibility at the encoding end, we also examined the impact of various MPEG-2 encoding parameters on the quality of the reconstructed HDTV video sequences. The parameters include bit rate, the structure of picture organization, as well as temporal processing     

MPEG-4标准浅析

对支持多媒体应用的MPEG-4标准关键技术进行分析，归纳了MPEG-4标准的新特点，并对MPEG-4的应用前景进行了展望。