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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中基于上下文的自适应二进制算术编码 总被引:1,自引:0,他引:1
基于上下文自适应二进制算术编码(CABAC)H.264/AVC采用的高效熵编码方法之一,它由二进制化、上下文建模、算术编码三个步骤构成。详细阐述了CABAC的整个编码过程,并对它与VLC/CAVLC在编码性能上作了比较。 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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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是ITU—T和ISO/IEC两大国际组织共同制定的新一代视频压缩编码标准。指数哥伦布编码是熵编码的重要主要组成模块。对从码流中提取的句法元素进行编码。它与基于上下文自适应的可变长编码(CAVLC)或基于上下文自适应的算术编码(CABAC)共同构成了熵编码。本文全面介绍了指数哥伦布的基本原理及本设计中指数哥伦布编码的句法元素,重点阐述了指数哥伦布编码器的硬件实现方法。实验结果表明,该设计能满足分辨率为1920×1080的视频序列的实时编码对质量和速度的要求。 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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《Signal Processing: Image Communication》2009,24(4):263-276
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. 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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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
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主要针对当前H.264/AVC中CAVLC中的标准解码方法 TLSS查表时存在查表时间长的问题,提出了一种全新的基于哈希表快速查询的CAVLC解码查表优化方法。在CAVLC解码查表中引入哈希表查找技术,提高了CAVLC解码查表速度,降低了CAVLC解码中不规则可变长码表(UVLCT)的码字获取时间,从而减少CAVLC解码查表时间。实验仿真结果表明,在没有丝毫降低视频解码质量前提下,相比于标准TLSS方法,提出的新算法可以提高约18%~22%的表查找时间。 相似文献
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Context-based adaptive variable length coding (CAVLC) and context-based adaptive binary arithmetic coding (CABAC) are entropy coding methods employed in the H.264/AVC standard. Since these entropy coders are originally designed for encoding residual data, which are zigzag scanned and quantized transform coefficients, they cannot provide adequate coding performance for lossless video coding where residual data are not quantized transform coefficients, but the differential pixel values between the original and predicted pixel values. Therefore, considering the statistical characteristics of residual data in lossless video coding, we newly design each entropy coding method based on the conventional entropy coders in H.264/AVC. From the experimental result, we have verified that the proposed method provides not only positive bit-saving of 8% but also reduced computational complexity compared to the current H.264/AVC lossless coding mode. 相似文献