共查询到19条相似文献,搜索用时 171 毫秒
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H.264采用整数离散余弦变换(Discrete Cosine Transform,DCT)、多种量化方法选择和更精确的帧内预测等先进技术,提高了解码图像质量,但增加了算法的计算复杂度。利用MMX/SSE/SSE2指令集对H.264解码器的关键算法进行优化,在不影响图像质量的情况下,实验证明可以显著提高算法的执行效率。 相似文献
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为了提高编码性能,H.264采用了RDO(率失真优化),但与此同时带来的是计算复杂度的增加.本文着重分析了H.264中快速帧内预测模式选择的问题.为了降低帧内预测模式选择的计算复杂度,提出了一种高效的快速帧内预测模式选择算法.首先,对Pan的基于边缘方向直方图的快速算法进行了改进,同时提出了基于参考象素特征的4×4快速帧内预测模式选择算法,并将两者进行了结合.实验结果表明,本文算法和H.264校验模型JM61相比,I帧编码时间降低61%~69%,而PSNR基本保持不变,输出码率仅略有增加;与Pan的基于边缘方向直方图快速算法相比,本文算法的I帧编码时间降低12%~33%,PSNR和输出码率均基本保持不变. 相似文献
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H.264是目前应用最广泛的视频编码标准,相比于以前的标准,H.264在编码效率上得到了很大的提高.但是相应的计算复杂度也是成倍增加.在此提出一种改进的预测算法,通过时域相关性系数和空域相关性系数排除帧内预测或帧外预测的一些模式,初步减少编码复杂度,再针对分析结果利用已有的快速选择算法对帧内帧外预测模式的最优预测模式组进行预测,进一步加快编码速度.实验结果表明,改进的快速算法在不影响编码质量的同时能够有效地减少计算复杂度和提高编码速度. 相似文献
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H.264/AVC帧内预测技术采用率失真优化策略进行最优化编码模式选择,提高了I帧的编码效率,但同时也提高了计算复杂度。本文提出了一种帧内预测模式的快速选择算法,基于亮度块的方向特性,通过一些复杂度不大的计算,选择少数几个可能性较大的预测模式进行率失真代价计算,得到最佳亮度预测模式,并以 计算代替率失真代价计算选择最佳色度预测模式,降低了计算复杂度,提高了编码速度。实验结果表明,本文提出的算法在保证图像质量的同时,编码时间平均降低了48%,而码率增加很小。 相似文献
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H.264/AVC帧内预测技术采用率失真优化策略进行最优化编码模式选择,提高了I帧的编码效率,但同时也提高了计算复杂度。提出了一种帧内预测模式的快速选择算法,基于亮度块的方向特性,通过一些复杂度不大的计算,选择少数几个可能性较大的预测模式进行率失真代价计算,得到最佳亮度预测模式,并以SATD计算代替率失真代价计算选择最佳色度预测模式,降低了计算复杂度,提高了编码速度。实验结果表明,提出的算法在保证图像质量的同时,编码时间平均降低了48%,而码率增加很小。 相似文献
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H.264帧内预测算法的研究与优化 总被引:1,自引:0,他引:1
H.264作为最新的视频编码标准,为了获得最佳的帧内和帧间预测,H.264采用了率失真优化(RDO)技术,提高了编码质量,降低了比特率。RDO技术对所有的帧内/帧间预测模式采用全搜索算法,导致了很高的计算复杂度。本文中,引入了一种新颖的快速帧内预测算法,改变模式选择的顺序,利用临块之间预测模式的相关性,通过阈值比较及绝对差值和排序的方式,对H.264帧内预测算法进行了优化。实验结果表明:与全搜索算法相比,快速算法降低了30%左右的编码时间,而信噪比、码流几乎不变。 相似文献
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Compared with other existing video coding standards, H.264/AVC can achieve a significant improvement in compression performances.
A robust criterion named the rate distortion optimization (RDO) is employed to select the optimal coding modes and motion
vectors for each macroblock (MB), which achieves a high compression ratio while leading to a great increase in the complexity
and computational load unfortunately. In this paper, a fast mode decision algorithm for H.264/AVC intra prediction based on
integer transform and adaptive threshold is proposed. Before the intra prediction, integer transform operations on the original
image are executed to find the directions of local textures. According to this direction, only a small part of the possible
intra prediction modes are tested for RDO calculation at the first step. If the minimum mean absolute error (MMAE) of the
reconstructed block corresponding to the best mode is smaller than an adaptive threshold which depends on the quantization
parameter (QP), the RDO calculation is terminated. Otherwise, more possible modes need to be tested. The adaptive threshold
aims to balance the compression performance and the computational load. Simulation results with various video sequences show
that the fast mode decision algorithm proposed in this paper can accelerate the encoding speed significantly only with negligible
PSNR loss or bit rate increment.
This work is supported in part by China National Natural Science Foundation (CNSF) under Project No.60572045, the Ministry
of Education of China Ph.D. Program Foundation under Project No.20050698033, and by a Cooperation Project (2005.7– 2007.7)
with Microsoft Research Asia. 相似文献
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一种基于H.264/AVC压缩域的GOP级视频场景转换检测算法 总被引:1,自引:0,他引:1
本文提出了一种基于H.264/AVC压缩域的GOP(Group of Pictures)级视频场景转换检测算法.该算法利用H.264/AVC基本档次码流中的帧内预测模式、运动矢量和宏块编码类型等可用信息,提出了基于子块的色度模式差异、累积运动值和累积帧内宏块数等三个判决准则,然后综合利用这三个判决准则,提出了一种GOP级的视频场景转换检测算法.实验结果表明,与现有的一个COP级场景检测算法对比,本文提出的GOP级视频场景转换检测算法可以获得更好的检测性能. 相似文献
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H.264中帧内编码算法及其快速实现研究 总被引:2,自引:0,他引:2
新的视频编码标准H.264使用了帧内预测的编码方式,这与以往的视频编码标准相比在很大程度上提高了帧内编码效率,节省了码流,但同时也增加了编码器的复杂度,因此有必要对H.264帧内编码算法进行快速实现,以满足实时视频通信的要求.首先详细介绍H.264帧内编码的实现过程,然后使用SIMD(单指令多数据流)技术对帧内编码进行快速实现.实验结果表明,与未使用快速算法相比,使用该快速实现算法后,H.264帧内编码速度得到显著提高. 相似文献
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Yunfei Wang Jianwen Chen Yun He 《Journal of Visual Communication and Image Representation》2012,23(4):599-603
In a decade where the prominence of video applications has become increasingly prevalent, the optimization of video coding processes remains as important as ever. The directional intra prediction has been proved as an effective tool for intra picture coding. However, in a directional intra prediction based coding structure, there is a considerable gap between the transform efficiency of DCT and the optimal transform KLT. In this paper, we analyze these problems and propose a pixel-wise directional intra prediction (PDIP) method to solve this problem. This method exploits the reconstruction value of the adjacent pixels to predict the current pixel, and keeps the block-based lossy coding structure of H.264/AVC. The proposed method can significantly improve the coding efficiency with little decoding complexity increment. 相似文献
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In order to improve the coding performance of intra rough mode decision,a SATD-based Lagrange multiplier selection algorithm was proposed for H.265/HEVC.The characteristic of Hadamard transform was first analyzed,and following the new Lagrange multiplier calculation approach based on the distortion measurement of SATD was constructed according to the rate-distortion theory.Then combing the principle of discrete cosine transform,the related parameters were obtained by the formula derivation.Experimental results show that the proposed method supports more accurately intra prediction mode decision,and the reconstruction video quality is improved in average while keeping the same bit-rate. 相似文献
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H.264/AVC以巨大编码复杂度为代价,在获得更高压缩率的同时,编码实时性也随之降低。针对视频编码中重要且耗时的帧间预测技术,分析了宏块平坦度和时空相关性,提出了一种快速的预测模式选择算法。仿真实验结果表明,本文提出算法与H.264/AVC(JM12.2)标准算法相比,在保持重建视频图像质量和输出码流结构的前提下,平均节省约70%的编码时间,并继承了H.264/AVC低码率的编码优势。 相似文献
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《Journal of Visual Communication and Image Representation》2008,19(3):175-183
The recent video coding standard H.264/AVC show extremely higher coding efficiency compare to any other previous standards. H.264/AVC can achieve over 50% of bit rate saving with same quality using the rate–distortion process, but it brings high computational complexity. In this paper, we propose an algorithm that can reduce the complexity of the codec by reducing the block mode decision process adaptively. Block mode decision process in H.264/AVC consists of inter mode decision process and intra mode decision process. We deal with reduction method for inter and intra mode decision. In this paper an efficient method is proposed to reduce the inter mode decision complexity using the direct prediction methods based on block correlation and adaptive rate distortion cost threshold for early stopping. The fast intra mode reduction algorithm based on inter mode information is also proposed to reduce the computational complexity. The experimental results show that the proposed algorithm can achieve up to 63.34–77.39% speed up ratio with a little PSNR loss. Increment in bit requirement is also not much noticeable. 相似文献