一种新的H.264多参考帧快速搜索算法

H.264/AVC是目前最新的视频编码国际标准.在H.264/AVC中,由于采用了多参考帧,运动估计部分的复杂度大大增加了.虽然JVT采用的快速运动估计(FME)提案能极大地提高搜索速度,但只是加快了一帧的搜索速度.本文在FME基础上提出了一种新的多参考帧快速搜索算法(FMRSA),它利用当前块周围的块信息来预测将要搜索的参考帧的范围,并在具体搜索过程中运用提前中断的方法加快整个搜索过程.实验证明本算法比标准快速搜索法搜索5个参考帧能在PSNR降低不超过0.05dB、码率增加不超过2.32%的情况下节省至少56.5%的时间.     

分数像素运动矢量代价产生器的VLSI设计

针对H．264／AVC视频编码器的系统芯片设计,通过分析分数像素运动估计（FME）模块的数据并行度和硬件利用率,探讨了分数像素运动矢量代价产生器的复用结构,再依据FME模块的具体设计约束,提出了可以复用产生1／2像素和1／4像素运动矢量代价的硬件实现结构,并且在FPGA开发板上进行了分数像素运动矢量代价产生器的设计验证。     

H．264／AVC编码器中分数像素的插值算法优化

文中基于H．264/AVC视频编码器的系统芯片设计,对分数像素运动估计(FME)的亮度像素插值算法进行了简化调整;使用JM7．3参考代码模拟了不同分数像素插值算法对编码器性能的影响,通过分析这些插值算法的编码效率和芯片上的实现代价,提出了可以有效节约硬件实现代价的分数像素插值算法。试验结果表明优化后的插值算法可以使分数像素插值结构的硬件实现代价降低30%以上,而平均编码峰值信噪比(PSNR)和压缩率只有很小的损失。     

基于HEVC标准的全高清CABAC编码器设计

2013年1月,新一代国际视频编码标准HEVC在视频编码专家组织和动态图像专家组织的合作下成功制定。HEVC视频标准采用了一系列关键技术如:灵活编码结构、大尺寸变换单元和改进的去方块滤波等,将码流压缩比率在H.264标准基础上进一步提高。基于上下文的自适应算术熵编码作为编码结构的最后一个环节,是视频图像压缩的重要过程。提出了一种全高清CABAC编码器硬件架构,可以实现1 080p视频图像的实时编码。     

新一代视频编码技术HEVC算法分析及比较

新一代视频编码标准HEVC更倾向于处理高清视频,实现在设备复杂度有一定增加的前提下提高视频,尤其是高清视频的编码效率。结合现行的H.264标准,对比了HEVC标准在编码结构、帧内预测、帧间预测以及熵编码技术上的改进和算法上的优化。对HEVC的具体编码技术进行分析,并将HEVC与H.264编码性能进行了比较。实验结果表明,HEVC在编码性能上有了明显提高。     

一种HEVC快速编码单元划分方法

新一代视频编码标准HEVC(High Efficiency Video Coding)巨大的编码优势将成为数字视频产业的首选编解码标准.压缩率的提高导致了计算复杂度的大幅度增加,因此本文针对HEVC视频编码标准的特性,基于四叉树的编码结构,通过将编码单元的划分与SSIM(Structural Similarity index,结构相似度)相结合,优化了帧内编码效率.     

基于H.264/AVC扩展的可伸缩视频编码技术

联合视频组（JVT）最近正在研究开发基于H.264/AVC标准的可伸缩视频编码（SVC）方法,并且准备将其纳入H.264/AVC标准的扩展中.本文概述了SVC的编码结构,并重点讲述了H.264/AVC可伸缩编码扩展的关键技术.     

基于子带/小波分解的视频编码可分级性研究

视频编码的可分级性是MPEG-4标准视频部分所要求的重要功能之一.本文提出了一种基于子带/小波分解的可分级性结构,以支持视频编码的空域分层、时域分层以及混合分层,并通过实验验证了它的有效性.     

应用于多视点视频压缩的多参考B帧快速编码算法

基于H.264平台就多视点视频压缩中多参考帧技术存在计算复杂度高的现状,根据多视点视频序列特性,提出了一种针对多参考B帧的快速多视点视频编码压缩算法。新算法改进了多参考帧列表策略,并结合多视点视频序列的时空域相关性特性,提出了适用于多视点视频编码的参考帧列表调整策略。此外,还针对多种块模式编码引入了块模式预判策略。新算法在保证率失真性能的基础上,有效地降低了计算复杂度,提高了多视点视频编码速度。虽然本文是基于M-Picture编码结构实现了新算法,但它同样适用于其它应用多参考B帧预测技术的多视点视频编码结构中。     

基于深层特征学习的高效率视频编码中帧内快速预测算法

高效视频编码(HEVC)标准相对于H.264/AVC标准提升了压缩效率,但由于引入的编码单元四叉树划分结构也使得编码复杂度大幅度提升.对此,该文提出一种针对HEVC帧内编码模式下编码单元(CU)划分表征矢量预测的多层特征传递卷积神经网络(MLFT-CNN),大幅度降低了视频编码复杂度.首先,提出融合CU划分结构信息的降分辨率特征提取模块;其次,改进通道注意力机制以提升特征的纹理表达性能;再次,设计特征传递机制,用高深度编码单元划分特征指导低深度编码单元的划分;最后建立分段特征表示的目标损失函数,训练端到端的CU划分表征矢量预测网络.实验结果表明,在不影响视频编码质量的前提下,该文所提算法有效地降低了HEVC的编码复杂度,与标准方法相比,编码复杂度平均下降了70.96％.     

An Efficient VLSI Architecture of Fractional Motion Estimation in H.264 for HDTV

Fractional Motion Estimation (FME) in high-definition H.264 presents a significant design challenge in terms of memory bandwidth, latency and area cost as there are various modes and complex mode decision flow, which require over 45% of the computation complexity in the H.264 encoding process. In this paper, a new high-performance VLSI architecture for Fractional Motion Estimation (FME) in H.264/AVC based on the full-search algorithm is presented. This architecture is made up of three different pipeline processors to establish a trade-off between processing time and hardware utilization. The computing scheme based on a 4-pixel interpolation unit with a 10-pixel input bandwidth is capable of processing a macroblock (MB) in 870 clock cycles. The final VLSI implementation only requires 11.4 k gates and 4.4kBytes of RAM in a standard 180 nm CMOS technology operating at 290 MHz. Our design generates the residual image and the best MVs and mode in a high throughput and low area cost architecture while achieving enough processing capacity for 1080HD (1920 × 1088@30fps) real-time video streams.     

VLSI Architecture Design of Fractional Motion Estimation for H.264/AVC

The H.264/AVC Fractional Motion Estimation (FME) with rate-distortion constrained mode decision can improve the rate-distortion efficiency by 2–6 dB in peak signal-to-noise ratio. However, it comes with considerable computation complexity. Acceleration by dedicated hardware is a must for real-time applications. The main difficulty for FME hardware implementation is parallel processing under the constraint of the sequential flow and data dependency. We analyze seven inter-correlative loops extracted from FME procedure and provide decomposing methodologies to obtain efficient projection in hardware implementation. Two techniques, 4×4 block decomposition and efficiently vertical scheduling, are proposed to reuse data among the variable block size and to improve the hardware utilization. Besides, advanced architectures are designed to efficiently integrate the 6-taps 2D finite impulse response, residue generation, and 4×4 Hadamard transform into a fully pipelined architecture. This design is finally implemented and integrated into an H.264/AVC single chip encoder that supports realtime encoding of 720×480 30fps video with four reference frames at 81 MHz operation frequency with 405 K logic gates (41.9% area of the encoder).

H.264/AVC视频编码标准的技术特点及应用分析

H.264／AVC是ITU-T视频编码专家组和ISO／IEC运动图像专家组(MPEG)共同开发出来的最新视频编码标准,它具备许多新的技术特点,如:多模式运动预测、柔性宏块排序、整数变换、一致性变字长编码、内容自适应二进制算术编码、分层编码、错误约束机制、错误掩盖技术及高效的比特流切换技术等等。本文在阐述该标准系统层结构的基础上,分析其主要技术特点及H.264／AVC VBR码流特性,阐述该标准在IP网络及无线网络中的应用情况。     

Efficient Level and Zero Coding Methods for H.264/AVC Lossless Intra Coding

Since H.264/AVC was designed mainly for lossy video coding, the entropy coding methods in H.264/AVC are not appropriate for lossless video coding. Based on statistical differences of residual data in lossy and lossless coding, we develop efficient level and zero coding methods. Therefore, we design an improved context-based adaptive variable length coding (CAVLC) scheme for lossless intra coding by modifying the relative entropy coding parts in H.264/AVC. Experimental results show that the proposed method provides approximately 6.8% bit saving, compared with the H.264/AVC FRExt high profile.      

Mode-Dependent Templates and Scan Order for H.264/AVC-Based Intra Lossless Coding

In H.264/advanced video coding (AVC), lossless coding and lossy coding share the same entropy coding module. However, the entropy coders in the H.264/AVC standard were original designed for lossy video coding and do not yield adequate performance for lossless video coding. In this paper, we analyze the problem with the current lossless coding scheme and propose a mode-dependent template (MD-template) based method for intra lossless coding. By exploring the statistical redundancy of the prediction residual in the H.264/AVC intra prediction modes, more zero coefficients are generated. By designing a new scan order for each MD-template, the scanned coefficients sequence fits the H.264/AVC entropy coders better. A fast implementation algorithm is also designed. With little computation increase, experimental results confirm that the proposed fast algorithm achieves about 7.2% bit saving compared with the current H.264/AVC fidelity range extensions high profile.     

视频编码新标准H.264/AVC中的重要技术

简要介绍了最新的视频编码标准H．264／AVC的制定情况，详细叙述了H．264／AVC基本框架中采用的几个重要技术，最后比较了H．264／AVC和已有的几个编码标准的性能，H．264／AVC的压缩性能最好。     

H.264/AVC基本档次编码器实现时域可伸缩编码的方法

提出一种在H.264/AVC基本档次编码器中实现时域可伸缩编码的方案,该方案通过H.264/AVC标准所提供的多参考帧和内存管理控制操作机制来实现。对于现有的H.264/AVC解码器,不需任何修改,即可直接解码由本方案生成的时域可伸缩码流。     

H.264/AVC在3G移动通信中的应用

H.264/AVC是目前最新,也是性能最优异的国际视频压缩编码标准。在相同的视频质量下,H.264/AVC可以比MPEG-4(SP)节省大约一半的带宽,同时还具有更好的网络适应性和传输健壮性,在3G移动通信系统带宽资源紧张、通信环境恶劣的情况下,H.264/AVC应该是目前最合适的选择。从压缩效率、网络适应性和健壮性3个方面分析了H.264/AVC的新技术,并讨论了它们在3G移动通信中的应用。     

General Architecture for MPEG-2/H.263/H.264/AVC to H.264/AVC Intra Frame Transcoding

The latest international video-coding standard H.264/AVC significantly achieves better coding performance compared to prior video coding standards such as MPEG-2 and H.263, which have been widely used in today’s digital video applications. To provide the interoperability between different coding standards, this paper proposes an efficient architecture for MPEG-2/H.263/H.264/AVC to H.264/AVC intra frame transcoding, using the original information such as discrete cosine transform (DCT) coefficients and coded mode type. Low-frequency components of DCT coefficients and a novel rate distortion cost function are used to select a set of candidate modes for rate distortion optimization (RDO) decision. For H.263 and H.264/AVC, a mode refinement scheme is utilized to eliminate unlikely modes before RDO mode decision, based on coded mode information. The experimental results, conducted on JM12.2 with fast C8MB mode decision, reveal that average 58%, 59% and 60% of computation (re-encoding) time can be saved for MPEG-2, H.263, H.264/AVC to H.264/AVC intra frame transcodings respectively, while preserving good coding performance when compared with complex cascaded pixel domain transcoding (CCPDT); or average 88% (a speed up factor of 8) when compared with CCPDT without considering fast C8MB. The proposed algorithm for H.264/AVC homogeneous transcoding is also compared to the simple cascaded pixel domain transcoding (with original mode reuse). The results of this comparison indicate that the proposed algorithm significantly outperforms the mode reuse algorithm in coding performance, with only slightly higher computation.