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基于上下文的二进制算术编码(CABAC)是H.264/AVC中采用的一种高效的熵编码方法。本文简述算术编码的基本原理和CABAC的步骤.详细分析了二进制算术编码的过程。 相似文献
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H.264/AVC标准中的CABAC应用研究 总被引:3,自引:0,他引:3
H.264/AVC是由国际电信联盟(ITU)和国际标准化组织(ISO)共同制定的新一代视频编码标准。他的熵编码方案采纳了基于上下文的自适应二进制算术编码(CABAC)。CABAC是一种高效的熵编码,他利用上下文建模来降低符号间的冗余度,并且能够自适应码流的统计信息,获得很高的编码效率。深入研究了CABAC中的二进制化、上下文建模和自适应二进制算术编码器,并进行了相应的试验。实验结果表明:在相同的图像质量下,CABAC和CAVLC相比节省6%~15%的码率。 相似文献
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H.264/AVC是由国际电信联盟和国际标准化组织共同制定的新一代视频编码标准。在该标准中,规定了两种熵编码的模式,即基于上下文的自适应二进制算术编码(Context-bsaed Adaptive Binary Arithmetic Coding,CABAC)和基于上下文自适应可变长编码(Context-bsaed Adaptive Variable-Length Coding,CAVLC)。其中,CABAC作为一种新型的熵编码方法,将自适应技术、上下文模型化和二进制算术编码有地的结合在一起,达到了较高的压缩效率,CABAC的框架中还使用了一些新颖的方法,使得CABAC在软硬件的实现上更加方便。为了验证CABAC的实际效果,笔者应用参考程序对其进行了直观的测试,实验结果表明:在相同图像质量下,CABAC和CAVLC相比的确能节省较大的平均比特率。 相似文献
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H.264/AVC中二进制算术编码的分析与研究 总被引:1,自引:0,他引:1
算术编码是一种高效的熵编码方法,已经广泛应用于图像和视频编码中。文中简述了算术编码的基本原理,介绍了可行的算术编码算法,详细分析了H.264/AVC的CABAC中采用的自适应二进制算术编码的算法并对其性能进行了测试。 相似文献
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本文基于H.265/HEVC视频编码标准,实现了CABAC编码中二进制算术编码器常规编码模式下的一种硬件流水线结构,根据算法特性设计并优化了编码器的硬件架构,将概率状态数据储存在SRAM中,并使用查找表优化概率估计更新运算;对编码数据进行打包处理,简化概率估计更新带来的计算,以优化视频数据流编码速度;二进制算术编码采用多级流水线结构,支持四路并行编码.仿真结果表明,本文的硬件CABAC二进制算术编码器平均每时钟周期可以完成4个bin的编码,符合较高帧率的1080p视频实时编码要求. 相似文献
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AVS+是我国2012年颁布的新一代视频编码标准。AVS+中采用了两种熵编码方法,一种是基于上下文的自适应变长编码CAVLC;另一种为基于上下文的自适应二进制算术编码CABAC。已经有人对H.264标准比较了两种编码体制的优劣,本文针对AVS+编码应用,简述分析二者算法原理,对照比较其特点,通过测试表明CABAC耗时稍长,但是比CAVLC更加高效。 相似文献
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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。 相似文献
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Since context-based adaptive binary arithmetic coding (CABAC) as the entropy coding method in H.264/AVC was originally designed
for lossy video compression, it is inappropriate for lossless video compression. Based on the fact that there are statistical
differences of residual data between lossy and lossless video compression, we propose an efficient differential pixel value
coding method in CABAC for H.264/AVC lossless video compression. Considering the observed statistical properties of the differential
pixel value in lossless coding, we modified the CABAC encoding mechanism with the newly designed binarization table and the
context-modeling method. Experimental results show that the proposed method achieves an approximately 12% bit saving, compared
to the original CABAC method in the H.264/AVC standard. 相似文献
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在H.264视频压缩标准中采用了高效的算术编码CABAC方案,CABAC提高了编码效率,但同时增加了编码复杂度。分析CABAC的复杂度,指出CABAC优化方向,提出其低复杂度实现算法。主要从上下文模型、重要图和宏块类型的CABAC编码3个方面对CABAC软件算法进行了优化,并在JM参考软件中进行了验证,实验结果表明CABAC的编码复杂度降低了40%。 相似文献
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Szu-Wei Lee C.-C. Jay Kuo 《Journal of Visual Communication and Image Representation》2011,22(6):557-562
In this work, we propose a novel entropy coding mode decision algorithm to balance the tradeoff between the rate-distortion (R-D) performance and the entropy decoding complexity for the H.264/AVC video coding standard. Context-based adaptive binary arithmetic coding (CABAC), context-based adaptive variable length coding (CAVLC), and universal variable length coding (UVLC) are three entropy coding tools adopted by H.264/AVC. CABAC can be used to encode the texture and the header data while CAVLC and UVLC are employed to encode the texture and the header data, respectively. Although CABAC can provide better R-D performance than CAVLC/UVLC, its decoding complexity is higher. Thus, by taking the entropy decoding complexity into account, CABAC may not be the best tool, which motivates us to examine the entropy coding mode decision problem in depth. It will be shown experimentally that the proposed mode decision algorithm can help the encoder generate the bit streams that can be decoded at much lower complexity with little R-D performance loss. 相似文献
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CABAC熵编码机制下有效的变换域码率估计技术 总被引:1,自引:1,他引:0
CABAC是H.264/AVC视频压缩标准中采用的一种熵编码机制,结合RDO模式选择技术,可以降低20%的码率.在RDO模式选择过程中,需要对编码块的每一种候选模式进行熵编码以获得编码位数,这在很大程度上增加了视频编码的计算复杂度.为了避免复杂的Lagrange耗费计算,本文第一次提出了一种CABAC熵编码机制下的变换域码率估计方法,基于量化变换系数和运动向量差对熵编码位数进行估计.在此基础上,本文将码率估计技术应用在RDO模式选择中,提出了基于码率估计的快速模式选择算法,减少了模式选择的计算时间.模拟结果显示,本文提出的CABAC熵编码机制下的变换域码率估计技术在对编码性能影响不大的情况下,减少了模式选择中51%的率失真耗费计算时间,采用全搜索运动估计算法时,节省33%的总编码时间. 相似文献
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This paper uses joint algorithm and architecture design to enable high coding efficiency in conjunction with high processing speed and low area cost. Specifically, it presents several optimizations that can be performed on Context Adaptive Binary Arithmetic Coding (CABAC), a form of entropy coding used in H.264/AVC, to achieve the throughput necessary for real-time low power high definition video coding. The combination of syntax element partitions and interleaved entropy slices, referred to as Massively Parallel CABAC, increases the number of binary symbols that can be processed in a cycle. Subinterval reordering is used to reduce the cycle time required to process each binary symbol. Under common conditions using the JM12.0 software, the Massively Parallel CABAC, increases the bins per cycle by 2.7 to 32.8× at a cost of 0.25 to 6.84% coding loss compared with sequential single slice H.264/AVC CABAC. It also provides a 2× reduction in area cost, and reduces memory bandwidth. Subinterval reordering reduces the critical path delay by 14 to 22%, while modifications to context selection reduces the memory requirement by 67%. This work demonstrates that accounting for implementation cost during video coding algorithms design can enable higher processing speed and reduce hardware cost, while still delivering high coding efficiency in the next generation video coding standard. 相似文献