共查询到20条相似文献，搜索用时 15 毫秒
1.
为了更好地适应网络及终端的多样性,本文针对基于H.264的可伸缩编码,提出了一种基于运动区域的自适应可伸缩编码的优化方案.该方案根据基本层的运动信息及编码模式自动提取图像的运动感兴趣区域,并以独立片的形式对其进行时间,空间和质量上的可伸缩编码,实现选择性增强.实验结果表明,该方案不仅能大幅降低编码复杂度,而且使增强层码流集中包含运动区域信息,从而提高运动区域的重建质量及整幅图像的主观质量. 相似文献
2.
Scalable video coding is an ongoing standard, and the current working draft (WD) is to be finalized as an extension of H.264/AVC. It provides scalability at the bit stream level with good compression efficiency and allowing free combinations of spatial, temporal and quality scalability. In the WD, a uniform up‐sampling filter is employed to interpolate the base layer frames. This technique achieves high interpolated precision for both luma component and chroma components, but it results in extremely large encoding time which obstructs it from practical use. This paper proposes an improved up‐sampling filter design for spatially scalable video coding. It makes use of a basic characteristic of human vision system and intends to assign different filters for different components. Specifically, current usage of the 6‐tap up‐sampling filter is only for luma component, but for chroma components, much more simplified filter such as 4‐tap filter or 2‐tap filter should be used instead. Experimental results show that improved up‐sampling filter design reduces the computational complexity significantly with negligible coding loss and bit‐rate increases. © 2008 Wiley Periodicals, Inc. Int J Imaging Syst Technol, 17, 315–319, 2007 相似文献
3.
4.
《成像科学杂志》2013,61(3):311-319
AbstractIntra coding is used for reducing the spatial redundancy in video coding. H.264 supports several macroblocks of predictions for intra coding such as luma block four 16×16 modes, nine 4×4 modes and chroma block four modes, which significantly improve intra coding efficiency, but increase the encoding complexity. In order to select the best mode, we need to calculate the cost of the various modes. In this paper, a fast intra prediction mode decision for H.264/AVC video coding is proposed. Based on Laplacian, this intra prediction mode decision detects edges and selects the best mode for the block. This mode decision can shorten the time to reduce the encoding time. The experimental results show that the proposed algorithm achieves an encoding time saving of 70% on average. 相似文献
5.
针对最新的视频编码标准H．264,设计了一种基于差错估计的容错算法。该算法结合信道条件,估计差错在视频编码帧之间的扩散;根据每个宏块差错的程度,自适应地判断是否对该宏块进行帧内编码,从而抑制差错的积累。在存在反向信道的环境中,该算法可以利用解码器反馈的实际宏块错误信息,跟踪差错扩散,对其进行更准确的估计,以提高容错性能。仿真表明,在各种信道条件下,该算法相对于随机帧内宏块更新算法．重建图像平均峰值信噪比有1．3～2．5dB的提高。同时,该算法对信道估计的要求不高,运算量和存储量的增加较低,具有实用性。 相似文献
6.
Chuen‐Ching Wang Bo‐Yu Chen 《International journal of imaging systems and technology》2008,18(4):257-264
This article proposes a new fragile watermarking scheme named bit‐plane watermarking (BPW) which considers ways to improve coding efficiency whereas providing watermarking capability. Because of the use of the run‐length coding strategy for embedding watermark information, the BPW not only verifies the authenticity and integrity of video streams, but also can recompress the bit streams for improving the compression ratio. To verify the effectiveness of this new concept, we select the MPEG‐4 FGS as the platform for implementation. The watermark is embedded in the bit‐plane blocks of MPEG‐4 FGS enhancement layer bitstream, and the coefficient in each bit‐plane block is automatically selected so that the run‐length symbols can be reduced and the location of embedded bits is not required to memorize. The effectiveness of the proposed scheme is demonstrated in a series of experimental simulations. It is shown that the scheme successfully detects changes made to the content of MPEG‐4 FGS video streams and identifies the specific location at which these changes have been made. Furthermore, the results show that the scheme can further reduce the length of compressed bit stream. © 2008 Wiley Periodicals, Inc. Int J Imaging Syst Technol, 18, 257–264, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). 相似文献
7.
This paper presents a reversible data hiding (RDH) method, which is designed by combining histogram modification (HM) with run-level coding in H.264/advanced video coding (AVC). In this scheme, the run-level is changed for embedding data into H.264/AVC video sequences. In order to guarantee the reversibility of the proposed scheme, the last nonzero quantized discrete cosine transform (DCT) coefficients in embeddable 4×4 blocks are shifted by the technology of histogram modification. The proposed scheme is realized after quantization and before entropy coding of H.264/AVC compression standard. Therefore, the embedded information can be correctly extracted at the decoding side. Peak-signal-noise-to-ratio (PSNR) and Structure similarity index(SSIM), embedding payload and bit-rate variation are exploited to measure the performance of the proposed scheme. Experimental results have shown that the proposed scheme leads to less SSIM variation and bit-rate increase. 相似文献
8.
基于提高教学平台中音视频处理的速度及系统的灵活性问题,在采用H.264数字视频编码标准的情况下分析H.264技术特点,着重说明H.264的实现方法及改进办法,给出系统的实现方案,该系统基本满足教学的需要,便于与多媒体服务器搭配使用,同时降低制造和维护成本. 相似文献
9.
10.
针对视频通信中时域误码掩盖中运动矢量恢复存在偏差的问题,提出了一种依据相似三角形特点的运动矢量估算方法。同时,利用受损块与前续块、邻域块的运动的时空相关性,提出了一种基于运动时空相关度的时域掩盖算法:对于受损块,采用提出的相似三角形运动矢量估算法和拉格朗日插值法分别估算其运动时域相关和运动空域相关的运动矢量,然后评估受损块的运动时空相关度,据此对估算的运动时域和运动空域相关的运动矢量进行加权平均以得到最终掩盖的运动矢量,从而实现受损块的时域掩盖。仿真结果表明,对不同宏块丢失率或不同视频序列,该算法均可比传统算法恢复出更高质量的图像。 相似文献
11.
本文提出一种快速实现H.264运动估计的算法。该算法利用视频图像中存在大量空/时域冗余这一特点,在运动估计过程中引入预判空间相关性和时域稳定性的方法,节省了大量不必要的计算步骤。试验结果表明,该算法运动估计时间仅为JM84的30.3%,峰值信噪比(PSNR)仅降低1.1%,码率平均增加3.95%。 相似文献
12.
13.
码字前缀分组的CAVLC解码优化 总被引：1，自引：0，他引：1
文章介绍了CAVLC编解码的原理并提出了一种快速查表方法。这种方法对于解码器码流输入,首先得到第一个1的位置,并把第一个1以及它前面的0作为码字的前缀。然后根据不同的码字要求,动态地选择进一步需要读入的码流位数。通过一次查表就可以得到正确输出,有效提高解码速度。 相似文献
14.
X3D裸眼可视立体显示器需要同时输入8个视点的信息,用户在一定角度范围内可以看到不同视角的立体画面显示.面向裸眼立体显示终端提出了一种立体视频编码方法,在编码端完成复杂的视差估计,压缩后的视差信息通过网络传输到立体显示终端以降低系统对用户终端的要求.用户终端采用基于视差图绘制的方法快速绘制出6个中间视点,实现裸眼可视立体显示器上的多视角立体画面显示.针对视差图的处理,给出了全局平滑和非边缘区域平滑两种视差图的处理方法.实验结果表明,与不对视差图进行平滑的方法相比,对视差图进行平滑能有效提高编码的整体率失真性能. 相似文献
15.
16.
An intra mode selection scheme is proposed in this work, which supports both downsizing transcoding and re‐quantization transcoding simultaneously. In the proposal, a total number of nonzero coefficients in precoded frame is used as criterion and a thresholding method is applied to select intra macroblock mode in re‐encoder. To calculate this threshold, which is related to re‐quantization parameter (denoted as Qr), we propose a Th_I‐Qr model which includes direct method and percentage I16MB method. In the former, an exponent model is proposed to describe relationship between the threshold and the Qr; while in the latter, the threshold Th_I is converted into percentage of macroblocks with I16MB mode in the downsized frame (denoted as per_16), and relationship between the per_16 and the Qr is also modeled as an exponent function. Then the two exponent models are all converted into linear regression model, and least square estimation is used to estimate the parameters of the models. Furthermore, if I4MB mode is selected for one macroblock, the intra prediction modes in precoded frame are utilized to select prediction mode for every 4 × 4 block of the macroblock in downsized frame to reduce computational complexity. We compared rate distortion performance and computational complexity of the proposed method with rate‐distortion optimization method. Simulation results demonstrate that on the precondition of compression performance of the proposal being close to the results of the rate‐distortion optimization method, the proposed method can save up to 30 and 80% in total encoding time and mode decision time, respectively. © 2009 Wiley Periodicals, Inc. Int J Imaging Syst Technol, 19, 340–349, 2009 相似文献
17.
在视频编码中,算法可定制的模块起着至关重要的作用.目前并没有资料对模块之间的关联度进行系统的调查研究,但是多模块算法的设计能够获得较好的全局最优化来代替局部优化,使得编码的性能与复杂度之间达到最佳平衡.怎样测量模块之间的关联度是一项非常有意义并且有趣的工作,本文尝试对模块间的关联性度量进行分析,并且给出了相关性因子的定量测试方法,最终我们通过关联性来为算法决定各个参数选择的优先顺序;实验以X264编码器为平台,给出了度量的相应结果,验证了本文提出的方法和理念,这对多模块联合算法优化有着重大的意义. 相似文献
18.
One method of measuring the detonation pressure in an explosive depends on observation of the shock waves produced by the explosive in a target material. Previous use of this method was confined to charges of highly brisant military explosives. The present paper describes a determination of the detonation pressure in lightly pressed pentaerythritol tetranitrate. and discusses applications to commercial explosives in small cartridge diameters. 相似文献
19.
H.264/AVC是JVT(联合视频组)和MPEG(活动图像编码专家组)联合提出的具有更高压缩效率的视频编码标准,主要分析本编码器主要采用的快速算法有:帧内模式快速选择算法、帧间模式快速选择算法、快速运动搜索算法等内容,对于进一步深化设计H.264/AVC编码器具有一定帮助。 相似文献
20.
《成像科学杂志》2013,61(6):339-350
AbstractThis paper presents a well organised fast mode decision scheme for H.264/AVC that systematically integrates and deploys applicable predictive resources using constructive compromise. This scheme is constructed by primary SKIP mode checking, spatial prior temporal hard decision (STHD), and succinct mode decision (SMD). The STHD is connected with the predictive macroblocks searched. In STHD, only when spatial hard decision fails, temporal hard decision is performed using the potential partition characteristic vector (PPCV) addressed. If it fails, too, then SMD takes care of mode checking also using PPCV. The SMD consists of succinct P16?×?16 mode decision and succinct geometric/statistical extension examination, which are formed as an effective two-stage judgment. Extensive experimental results demonstrate that the proposed method by systematically deploying the predictive resources can achieve 58–74% runtime savings in encoding QCIF, CIF and high definition videos with low performance losses. In addition, most processes of the proposed scheme could be implemented on logical operations, only. 相似文献