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提出了一种针对H.264标准的帧间编码模式快速自适应选择算法用以减少编码器的复杂度。该算法利用运动补偿后残差宏块的统计信息.将需要计算率失真代价函数的候选模式减少为一个模式组中包含的模式子集。由于该算法采用了重叠划分的模式组以及动态调整的门限.可以最大可能保证宏块的最佳编码模式处于所选择的模式组中,所以可以在编码质量下降很小的情况下,大幅度降低编码复杂度。实验表明,本算法平均可以节省编码时间52%.同时PSNR下降约为-0.05dB,不会影响主观视觉效果。 相似文献
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本文为MPEG02到JVT/AVC/H.264的转码提供了一种高效的块模式决策算法。这种新的决策算法既充分地利用了原始序列与当前待编码的H.264宏块相对应的16个MPEG-2宏块的信息。又参考了转码后序列的当前帧中与待编码宏块相邻的多个宏块的信息以及前一帧相应宏块的信息。本文在利用已知宏块的信息预测待编码宏块块模式的过程中。引入了“模式子集”的概念。由于这个子集中元素的数目较少,所以待编码宏块在该子集中挑选适合的块模式。可以极大地节省编码时间,提高编码效率。而与此同时对PSNR以及视频图像主观性能的影响不大。另外。本文进一步扩展了“主导宏块”的概念。并将之应用于块模式的决策中。从而有效地提高编码效率。 相似文献
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H.264的帧间宏块模式选择算法 总被引:2,自引:0,他引:2
H.264中定义了7种不同大小的帧间宏块模式,为了提高编码效率,编码时对每一种宏块模式都进行运动搜索,并利用率失真优化(RDO)分别计算编码代价,选择编码代价最小的模式作为帧间编码模式,但是计算量非常大,导致运动估计速度缓慢,很难实现实时编码。本文提出一种选择宏块模式的快速算法,通过宏块模式编码代价的比较,提前确定宏块模式,从而逐步减少不必要的宏块搜索和RDO计算。实验结果表明,此方法与全宏块模式搜索相比较,图像质量和码流只有少量变化,而编码速度显著提高。 相似文献
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本文为MPEG-2到JVT/AVC/H.264的转码提供了一种高效的块模式决策算法。这种新的决策算法既充分地利用了原始序列与当前待编码的H.264宏块相对应的16个MPEG-2宏块的信息,又参考了转码后序列的当前帧中与待编码宏块相邻的多个宏块的信息以及前一帧相应宏块的信息。本文在利用已知宏块的信息预测待编码宏块块模式的过程中,引入了"模式子集"的概念。由于这个子集中元素的数目较少,所以待编码宏块在该子集中挑选适合的块模式,可以极大地节省编码时间,提高编码效率,而与此同时对PSNR以及视频图像主观性能的影响不大。另外,本文进一步扩展了"主导宏块"的概念,并将之应用于块模式的决策中,从而有效地提高编码效率。 相似文献
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H.264快速帧间编码模式选择算法 总被引:2,自引:0,他引:2
本文提出了一种用于H.264编码的快速帧间编码模式选择算法。首先对低分辨率缩略图进行编码和R-D优化,选出该分辨率下帧间编码宏块中每个8x8块使用的最优帧间编码模式,然后将该模式映射为原始分辨率图像中对应16x16宏块的候选帧间编码模式子集,最后用通常的R-D优化方式从中选出原始分辨率下的最优模式。这种算法有效地减少了原图像编码过程中待测编码模式的数量,从而提高了编码速度。测试表明,此算法能够使编码速度提高将近一倍,同时码率增加不超过3%,PSNR下降不超过0.2dB。 相似文献
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为了实现尽可能高的编码效率,H.264采用了基于率失真优化的编码模式选择技术,然而为每一种编码模式都计算率失真代价极大的增加了编码时间。为了降低编码时间,提出了一种H.264快速模式选择算法,其主要思想是根据图像序列在时间以及空间上的相关性,为当前编码宏块预测一个编码模式子集,并仅对子集中的模式进行编码以及率失真优化,同时采用了适当的策略来避免由于不精确预测所带来的误差扩散。仿真结果表明,本算法平均减少了56%的编码时间,同时PSNR值平均下降0.13dB,最大下降不超过0.19dB。 相似文献
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H.264/AVC是一种由ITU-T视频编码专家组合ISO/IEC JTC1动态图像专家组联合提出的高度压缩视频编码器标准。然而H.264/AVC编码器较高的运算复杂度提高了多屏共享系统的延迟时间。H.264/AVC由多种开源的实现,其中X264因简单高效而得到广泛的应用。在此对多频共享系统的关键技术进行实现,分析X264编码器提供的运动估计算法并且提出一种优化的算法。实验表明,新的算法提高了编码的速度、减少了系统延迟时间,同时视频质量几乎没有产生损失。 相似文献
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H.264帧间模式快速判决 总被引:3,自引:3,他引:0
H.264标准采用率失真优化(RDO)技术提高了编码效率,但这是以较高的计算复杂度为代价的.提出一种快速模式判决算法,利用早期的SKIP模式判决以及运动代价来减少待选的模式.实验表明,该算法比起H.264标准显著提高了编码效率,而视频质量并没有太大的损失. 相似文献
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H.264/AVC中基于全零块检测的运动估计快速算法 总被引:4,自引:0,他引:4
全零块检测是面向低比特率的视频编码器常用优化方法之一.特别是与运动估计相结合,可以有效的减少编码器的计算复杂性.本文根据H.264/AVC中整数变换的特点,给出了相应的全零块检测门限,提出了一种基于全零块检测的运动搜索提前中止准则.针对H.264/AVC多编码模式的特点,进一步将全零块检测用于H.264/AVC中多种编码模式的选择,有效的提高了运动估计的效率.利用这种方法,在有效减少编码器的计算复杂性,提高H.264/AVC软件编码器编码效率的同时,可以保持比特率和图像质量基本不变. 相似文献
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A fast mode decision algorithm for H.264/AVC inter-prediction to reduce computational complexity of the H.264 encoder is presented. Experimental results show that the algorithm can save the entire encoding time by 77% on average while introducing only negligible loss in PSNR value and small increment of bit rate. 相似文献
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Rate distortion optimization for H.264 interframe coding: a general framework and algorithms. 总被引:1,自引:0,他引:1
Rate distortion (RD) optimization for H.264 interframe coding with complete baseline decoding compatibility is investigated on a frame basis. Using soft decision quantization (SDQ) rather than the standard hard decision quantization, we first establish a general framework in which motion estimation, quantization, and entropy coding (in H.264) for the current frame can be jointly designed to minimize a true RD cost given previously coded reference frames. We then propose three RD optimization algorithms--a graph-based algorithm for near optimal SDQ in H.264 baseline encoding given motion estimation and quantization step sizes, an algorithm for near optimal residual coding in H.264 baseline encoding given motion estimation, and an iterative overall algorithm to optimize H.264 baseline encoding for each individual frame given previously coded reference frames-with them embedded in the indicated order. The graph-based algorithm for near optimal SDQ is the core; given motion estimation and quantization step sizes, it is guaranteed to perform optimal SDQ if the weak adjacent block dependency utilized in the context adaptive variable length coding of H.264 is ignored for optimization. The proposed algorithms have been implemented based on the reference encoder JM82 of H.264 with complete compatibility to the baseline profile. Experiments show that for a set of typical video testing sequences, the graph-based algorithm for near optimal SDQ, the algorithm for near optimal residual coding, and the overall algorithm achieve on average, 6%, 8%, and 12%, respectively, rate reduction at the same PSNR (ranging from 30 to 38 dB) when compared with the RD optimization method implemented in the H.264 reference software. 相似文献
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《Signal Processing: Image Communication》2014,29(10):1063-1078
Multiview video coding (MVC) is the appendix H of H.264/AVC, and it requires a great amount of time to compress multiple viewpoints׳ video with complex prediction structures. To reduce the whole computational complexity of MVC, this paper proposes a fast macroblock (MB) encoding algorithm based on rate-distortion (RD) activity, and it includes the fast mode decision and the fast motion/disparity estimation. First, the RD activity type of the current MB is calculated by utilizing the Skip/Direct RD cost and the average RD costs of classified MB modes. Then, through utilizing the RD activity type and RD costs of the estimated modes, the selection of candidate modes, the early decision of Skip/Direct mode, and the reduction of Inter8×8 mode estimation are all presented in the fast mode decision. By using the RD activity type and the correlations of vectors, the selection of search center and the prediction of search range are introduced in the fast motion/disparity estimation. In addition, the proposed algorithm can be applied to temporal and inter-view views as well as anchor and non-anchor frames. An experiment with a wide range of video scenes, camera setups and quantization parameters was implemented, and the results confirmed that the proposed algorithm can reduce the encoding time significantly while maintaining a similar RD performance as the original MVC encoder. Compared to the state-of-the-art algorithms, the proposed algorithm also demonstrated better performances in the various test cases. 相似文献
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《Signal Processing: Image Communication》2005,20(7):595-623
In this paper, an efficient algorithm is proposed to reduce the computational complexity of variable-size block-matching motion estimation. We first investigate features of multiple candidate search centers, adaptive initial-blocksizes, search patterns, and search step-sizes, to match different motion characteristics and block-sizes. To avoid being trapped in local minima, the proposed algorithm uses multiple candidate motion vectors, which are obtained from different block-sizes. To further reduce the computation cost, a threshold-based early stop strategy according to the quantization parameter is suggested. With adaptive initial block-sizes, a merge-or-skip strategy is also proposed to reduce the computation for the final block-size decision. For the H.264/AVC encoder, simulations show that the proposed algorithms can speed up about 2.6–3.9 times of the original JM v6.1d encoder, which uses fast full-search for all block-sizes, and still maintain a comparable rate-distortion performance. 相似文献