共查询到20条相似文献,搜索用时 0 毫秒
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Yung-Lyul Lee Ki-Hun Han Gary J Sullivan 《IEEE transactions on image processing》2006,15(9):2610-2615
A new lossless intra coding method based on sample-by-sample differential pulse code modulation (DPCM) is presented as an enhancement of the H.264/MPEG-4 AVC standard. The H.264/AVC design includes a multidirectional spatial prediction method to reduce spatial redundancy by using neighboring samples as a prediction for the samples in a block of data to be encoded. In the new lossless intra coding method, the spatial prediction is performed based on samplewise DPCM instead of in the block-based manner used in the current H.264/AVC standard, while the block structure is retained for the residual difference entropy coding process. We show that the new method, based on samplewise DPCM, does not have a major complexity penalty, despite its apparent pipeline dependencies. Experiments show that the new lossless intra coding method reduces the bit rate by approximately 12% in comparison with the lossless intra coding method previously included in the H.264/AVC standard. As a result, the new method is currently being adopted into the H.264/AVC standard in a new enhancement project. 相似文献
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Hierarchical B-frames can bring high coding performance when introduced into H.264/AVC.However,the traditional rate control schemes can not work efficiently in such new coding framework.This article presents a rate control algorithm for hierarchical B-frames in H.264/AVC.Taking the feature of the dyadic hierarchical coding structure into consideration,the proposed algorithm includes group of pictures(GOP)layer,temporal layer and frame layer bits allocation.After frame layer bits allocation is complete,frame layer quantization parameters(QP)determination strategy is responsible for calculating the final QP.Experimental results show that compared with other rate control algorithms,the proposed one can improve the coding performance and reduce the mismatch of target bit rate and real bit rate. 相似文献
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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. 相似文献
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Long Xu Sam Kwong Hanli Wang Debin Zhao Wen Gao 《Signal Processing: Image Communication》2013,28(1):20-33
In this paper, a novel rate control scheme with sliding window basic unit is proposed to achieve consistent or smooth visual quality for H.264/AVC based video streaming. A sliding window consists of a group of successive frames and moves forward by one frame each time. To make the sliding window scheme possible for real-time video streaming, the initial encoder delay inherently in a video streaming system is utilized to generate all the bits of a window in advance, so that these bits for transmission are ready before their due time. The use of initial encoder delay does not introduce any additional delay in video streaming but benefits visual quality as compared to traditional one-pass rate control algorithms of H.264/AVC. Then, a Sliding Window Buffer Checking (SWBC) algorithm is proposed for buffer control at sliding window level and it accords with traditional buffer measurement of H.264/AVC. Extensive experimental results exhibit that higher coding performance, consistent visual quality and compliant buffer constraint can be achieved by the proposed algorithm. 相似文献
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码率控制是视频编码中非常重要的技术之一,任何标准离开码率控制其应用都会受到限制.H.264/AVC是目前最新的视频编码标准,本文根据H.264/AVC编码标准的特性及其HRD部分对码率控制的要求,提出了一种新的适合H.264/AVC的码率控制算法,该算法实现了率失真优化与码率控制的结合,使得在达到码率控制的同时也能保证较高的编码效率,同时在码率控制的过程中根据HRD缓冲区状态进行位分配调整,保证了编解码缓冲区既不上溢又不下溢.该算法作为技术提案已被H.264/AVC接受,并集成到H.264/AVC的校验模型软件中. 相似文献
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In this paper, an adaptive group-of-picture (AGOP) control is proposed to improve the coding performance for the H.264/AVC
system. The efficient algorithm is developed to find the quantized parameter with temporal correlation between inter-frames.
According to the estimated parameters, the GOP coding type can be adaptively selected as AGOP or BGOP (basic GOP). The rate
control with some decision functions is proposed to modify the quantization parameter (QP). The coding rate can accurately
meet the target rate with adjusting QP value dynamically, while keeping low computational overhead. Simulation results show
that the proposed algorithm can improve PSNR by about 1 dB in average compared with the original H.264/AVC reference software
(JM12.4), from various sequences testing. 相似文献
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《Signal Processing: Image Communication》2009,24(10):803-813
The H.264/AVC standard yields higher coding efficiency rates than other video coding standards. This is because it uses the rate-distortion optimization (RDO) technique, which selects the optimal coding mode and a reference frame for each macroblock (MB). In order to achieve this, the encoder has to encode a given block by exhaustively using all kinds of combinations (including different intra and inter-prediction modes). As a result, the computational complexity of video coding in H.264/AVC is extremely high. In this paper, two fast intra-/inter-mode-decision algorithms are proposed to reduce the complexity of the encoder. Both of these algorithms are based on the inter-frame correlation among adjacent pictures. For the fast intra-mode-decision, we used the intra-mode of the most-correlated MB at the reference frame to encode the current MB and the stationary property of the current MB was used for the fast inter-mode-decision. The simulation results show that the proposed algorithms significantly reduced the computational complexity with a negligible loss of PSNR and a slight increase in bitrate. 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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基于H.264/AVC的时空域差错隐藏方案 总被引:1,自引:0,他引:1
为了减小视频传输中的错误对解码端重建视频质量的影响,提出了一套结合时空域差错隐藏算法的方案。针对错误宏块在视频图像中呈随机分布的情况,首先将编码端帧内预测编码的思想引入到解码端,提出了一种方向性插值的空域差错隐藏算法;然后提出了一种基于8×8块的增强型时域差错隐藏算法来改善运动剧烈区域的质量;最后,提出了一种根据相邻宏块编码模式来选择时域或空域差错隐藏算法的切换策略。实验证明,提出的差错隐藏方案无论是在客观质量上,还是在主观质量上,都优于H.264/AVC的效果。 相似文献
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一种结合人眼视觉特性的H.264/AVC码率控制算法 总被引:1,自引:0,他引:1
针对应用于H.264/AVC视频编码中的码率控制算法G012的不足,提出了一种结合人眼视觉特性的H.264的码率控制算法.首先基于当前帧与前一帧的帧差比值来表示各帧图像的相对复杂程度,以此分配帧级的目标比特数;通过分析图像中的运动信息和纹理特征,给出了一种简单有效的度量宏块视觉敏感度的方法,并在基本单元层利用此视觉敏感... 相似文献
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Xiang Li Andreas Hutter Andr Kaup 《Journal of Visual Communication and Image Representation》2009,20(8):585-594
In this paper, an efficient one-pass frame level rate control algorithm is proposed for H.264/AVC, where the two essential problems in rate control, i.e., the budget allocation (BA) and the quantization parameter determination (QPD) are both considered. First, an efficient BA scheme is designed with special consideration of the inter-frame dependency. Accordingly, the error propagation caused by improper QP assignment in the motion compensation process is reduced and the total distortion is kept at a low level. Second, a better QPD method is developed based on an accurate rate model and a second feedback mechanism so that a high rate accuracy is guaranteed. Simulations verified the performance of the proposed algorithm. Compared with the fixed QP coding and the two recommended rate control algorithms (G012-MB and G012-Frame) in H.264/AVC reference software, up to 1.50, 1.12, and 0.94 dB were achieved with a higher rate accuracy in the coding efficiency test defined by ITU-T VCEG. Particularly, a more significant improvement was observed in slow movement scenarios: compared with G012-MB, a gain of 0.80 dB on average and 1.43 dB at maximum was obtained with 66.0% reduction of average rate mismatch. Compared with G012-Frame, the average and maximum gains are 0.34 and 1.06 dB, respectively. While at the same time, the average rate mismatch was reduced by 90.4%. Considering the low computational cost, the proposed algorithm is quite appealing to real-time video applications. 相似文献