期刊文献+
共找到4,749篇文章
< 1 2 238 >
每页显示 20 50 100
基于FPGA的H.264可变块运动估计算法的优化及实现
1
作者 李雨 龚龙庆 赵海婷 《微电子学与计算机》 2024年第6期11-19,共9页
可变块运动估计算法(Variable Block Size Motion Estimation,VBSME)是H.264标准中重要的组成部分。它不仅计算量大,而且耗时长。为了减少运动估计时间和计算量,本文采用硬件实现的方式,并提出了一种利用绝对差值和(Sum of Absolute Dif... 可变块运动估计算法(Variable Block Size Motion Estimation,VBSME)是H.264标准中重要的组成部分。它不仅计算量大,而且耗时长。为了减少运动估计时间和计算量,本文采用硬件实现的方式,并提出了一种利用绝对差值和(Sum of Absolute Differences,SAD)计算的树状结构进行数据重用的方案。该方案使得各单元间的数据流向明确,结构更简单。同时,本文还考虑到了帧间模式决策(Mode Decision,MD)和SAD计算可以并行计算的可行性,设计了相应的并行流水线结构。利用Xilinx xc7v585tffg1761-1开发板进行了仿真验证。结果表明,该方案可以一次性处理输入的256个像素数据,提高了实时性,并且达到了100%的数据利用率。此外,该方案支持最大分辨率为1920×1080,帧率为60帧/s,并具备低编码延时,满足了绝大多数场合的实时性要求。 展开更多
关键词 h.264 可变块运动估计 FPGA
下载PDF
基于申威SIMD指令的H.264编码优化 被引量:1
2
作者 黄朴 刘世巍 +1 位作者 张昊 王聪 《现代电子技术》 北大核心 2024年第6期49-54,共6页
国产化申威处理器出现较晚,其在多媒体领域中的性能还不突出,同时通用处理器中的单指令流多数据流(SIMD)因能有效提升并行处理能力而受到处理器厂商的青睐。为提高国产化自主平台申威架构的多媒体处理能力,结合申威架构Core3B体系的SIM... 国产化申威处理器出现较晚,其在多媒体领域中的性能还不突出,同时通用处理器中的单指令流多数据流(SIMD)因能有效提升并行处理能力而受到处理器厂商的青睐。为提高国产化自主平台申威架构的多媒体处理能力,结合申威架构Core3B体系的SIMD指令系统,提出一种基于申威架构的SIMD指令集H.264编码优化方法。结合申威处理器的并行结构特点,利用申威适配的Perf、Top指令等系统性能分析工具,采集两种主流视频分辨率下与编码性能强相关的高频热点函数,详细分析其程序并行化可行性,采用手工嵌入申威SIMD和访存扩展等汇编指令进行细粒度优化。实验结果表明,该方法在申威架构下的H.264平均编码性能提升了约30%。相应工作成果已推送到申威社区,增强了基于申威处理器的国产计算机在桌面多媒体应用领域的工作体验。 展开更多
关键词 单指令流多数据流 h.264标准 申威处理器 热点函数 程序并行化 细粒度
下载PDF
基于威焱831平台的H.264视频解码优化
3
作者 王聪 张昊 +1 位作者 刘世巍 黄朴 《现代电子技术》 北大核心 2024年第10期86-90,共5页
为提高威焱831平台的多媒体处理能力,解决H.264解码器解码效率低的问题,在提出SIMD指令级优化方法的同时,提出一种面向帧拷贝的优化方法。通过分析开源软件FFmpeg中H.264解码器的并行化特性,使用威焱平台性能分析工具解析影响视频解码... 为提高威焱831平台的多媒体处理能力,解决H.264解码器解码效率低的问题,在提出SIMD指令级优化方法的同时,提出一种面向帧拷贝的优化方法。通过分析开源软件FFmpeg中H.264解码器的并行化特性,使用威焱平台性能分析工具解析影响视频解码性能的热点函数。采用手工嵌入SIMD汇编指令的方式对关键模块热点函数进行优化,通过FFmpeg源码编译过程链接汇编实现的内存操作函数memcpy提升内存拷贝速度。实验结果表明,威焱831平台视频解码的平均性能提高26%,推动了威焱831处理器在多媒体应用领域的发展。 展开更多
关键词 威焱831平台 SIMD h.264解码器 FFMPEG 热点函数 解码效率
下载PDF
A Dual Domain Robust Reversible Watermarking Algorithm for Frame Grouping Videos Using Scene Smoothness
4
作者 Yucheng Liang Ke Niu +1 位作者 Yingnan Zhang Yifei Meng 《Computers, Materials & Continua》 SCIE EI 2024年第6期5143-5174,共32页
The proposed robust reversible watermarking algorithm addresses the compatibility challenges between robustness and reversibility in existing video watermarking techniques by leveraging scene smoothness for frame grou... The proposed robust reversible watermarking algorithm addresses the compatibility challenges between robustness and reversibility in existing video watermarking techniques by leveraging scene smoothness for frame grouping videos.Grounded in the H.264 video coding standard,the algorithm first employs traditional robust watermark stitching technology to embed watermark information in the low-frequency coefficient domain of the U channel.Subsequently,it utilizes histogram migration techniques in the high-frequency coefficient domain of the U channel to embed auxiliary information,enabling successful watermark extraction and lossless recovery of the original video content.Experimental results demonstrate the algorithm’s strong imperceptibility,with each embedded frame in the experimental videos achieving a mean peak signal-to-noise ratio of 49.3830 dB and a mean structural similarity of 0.9996.Compared with the three comparison algorithms,the performance of the two experimental indexes is improved by 7.59%and 0.4%on average.At the same time,the proposed algorithm has strong robustness to both offline and online attacks:In the face of offline attacks,the average normalized correlation coefficient between the extracted watermark and the original watermark is 0.9989,and the average bit error rate is 0.0089.In the face of online attacks,the normalized correlation coefficient between the extracted watermark and the original watermark is 0.8840,and the mean bit error rate is 0.2269.Compared with the three comparison algorithms,the performance of the two experimental indexes is improved by 1.27%and 18.16%on average,highlighting the algorithm’s robustness.Furthermore,the algorithm exhibits low computational complexity,with the mean encoding and the mean decoding time differentials during experimental video processing being 3.934 and 2.273 s,respectively,underscoring its practical utility. 展开更多
关键词 Robust reversible watermarking scene smoothness dual-domain U channel h.264 encoding standard
下载PDF
H.264/AVC自适应视频水印算法 被引量:2
5
作者 王泳 黄俊毓 +2 位作者 陈艺芳 张峻 陈晓宗 《西安电子科技大学学报》 EI CAS CSCD 北大核心 2023年第3期95-104,共10页
H.264/AVC视频数字水印在视频版权保护和信息隐藏等方面具有重要作用。目前,已有的水印研究,在水印嵌入过程中缺乏考虑视频画面复杂程度不断变化的问题,从而易导致两种后果:一是可能无法在画面复杂程度低的帧完整嵌入所需水印;二是无法... H.264/AVC视频数字水印在视频版权保护和信息隐藏等方面具有重要作用。目前,已有的水印研究,在水印嵌入过程中缺乏考虑视频画面复杂程度不断变化的问题,从而易导致两种后果:一是可能无法在画面复杂程度低的帧完整嵌入所需水印;二是无法充分利用画面复杂程度高的帧的冗余度。由此,分析在视频编码过程中与视频画面复杂程度相关的因素,提出一种根据视频画面复杂程度自适应嵌入水印的视频数字水印算法。在所提算法中,根据上一关键帧中符合嵌入条件的Intra_4×4子宏块的总个数预测获得当前关键帧的画面复杂度,并依据此复杂度自动调整每一水印比特重复嵌入的次数,从而达到自适应的目的。当由于预测失误而导致某一帧的水印嵌入失败,水印提取端则会舍弃该帧提取出的水印。提取端采用多数表决的机制提取水印。实验结果显示,该算法的水印具有良好的不可见性,且能保证码流的稳定性,优于近期相关文献的算法。算法对以重复嵌入水印比特为基础的研究具有启发意义。 展开更多
关键词 h264 数字水印 自适应 多数表决
下载PDF
混合级联H桥逆变器的新型SHEPWM功率均衡控制策略
6
作者 顾军 丁超 +2 位作者 卜荣荣 蔡润哲 王伟健 《电机与控制学报》 EI CSCD 北大核心 2024年第7期178-186,共9页
对于直流侧电压比为1∶1∶2的混合级联H桥逆变器,传统的指定谐波消除脉宽调制法(SHEPWM)存在各单元间输出功率不均衡问题,因此,提出一种双层功率均衡调制策略。首先,通过对消谐方程组中的基波幅值方程表达式进行等效拆分,使2个低压H桥... 对于直流侧电压比为1∶1∶2的混合级联H桥逆变器,传统的指定谐波消除脉宽调制法(SHEPWM)存在各单元间输出功率不均衡问题,因此,提出一种双层功率均衡调制策略。首先,通过对消谐方程组中的基波幅值方程表达式进行等效拆分,使2个低压H桥单元的输出电压基波幅值之和与高压H桥单元的输出电压基波幅值相等,实现了高低压H桥单元间的功率均衡,即外层功率均衡。其次,利用逻辑运算的方法对低压单元的初始驱动信号进行逻辑重组,实现2个低压单元间的功率均衡,即内层功率均衡;然后使用改进的实数型遗传算法(IRCGA-2)求出消谐方程组的解,消除指定的谐波,得到高质量的输出电压。最后,通过仿真和实验证明了调制策略的正确性与有效性。 展开更多
关键词 混合级联h桥逆变器 指定谐波消除 双层功率均衡 基波幅值 逻辑运算 改进的实数型遗传算法
下载PDF
浅谈H.264 H.265视频编码及其在安防系统的应用 被引量:1
7
作者 李克 《江西通信科技》 2023年第4期19-21,24,共4页
面对视频应用向高画质、高帧率、高压缩比方向发展的趋势,视频编解码标准也在日益更新,阐述了主要视频压缩标准H.264和H.265的主要技术参数和各自的优缺点,重点分析了H.265的关键技术及核心优势,探讨了H.265与安防系统结合给行业带来的... 面对视频应用向高画质、高帧率、高压缩比方向发展的趋势,视频编解码标准也在日益更新,阐述了主要视频压缩标准H.264和H.265的主要技术参数和各自的优缺点,重点分析了H.265的关键技术及核心优势,探讨了H.265与安防系统结合给行业带来的新机遇。 展开更多
关键词 视频编码 h.264 h.265 安防系统
下载PDF
Improved fast inra prediction algorithm of H.264/AVC 被引量:5
8
作者 LIU Qiong HU Rui-min ZHU Li ZHANG Xin-chen HAN Zhen 《Journal of Zhejiang University-Science A(Applied Physics & Engineering)》 SCIE EI CAS CSCD 2006年第z1期101-105,共5页
With advanced prediction modes of intra prediction, intra coding of H.264/AVC offers significant coding gains compared with previous video coding standards. It uses an important tool called Lagrangian rate-distortion ... With advanced prediction modes of intra prediction, intra coding of H.264/AVC offers significant coding gains compared with previous video coding standards. It uses an important tool called Lagrangian rate-distortion optimization (RDO)technique to decide the best coding mode for a block, but the computational burden is extremely high. In this paper, we proposed an improved fast intra prediction algorithm including block type selection and mode decision algorithm based on analysis of edge feature of a block. Our algorithm filters out unlikely block type and candidate modes to reduce the RDO calculations. Experimental results showed that the proposed algorithm can reduce the computation complexity of intra prediction from 52.90% to 56.31%, with 0.04 dB PSNR degradation and 2% increase of bit rate. 展开更多
关键词 h.264 AVC INTRA prediction VIDEO CODING
下载PDF
Fast mode decision algorithm for spatial resolutions down-scaling transcoding to H.264 被引量:1
9
作者 BU Jia-jun MO Lin-jian CHEN Chun YANG Zhi 《Journal of Zhejiang University-Science A(Applied Physics & Engineering)》 SCIE EI CAS CSCD 2006年第z1期70-75,共6页
A fast mode decision algorithm is proposed in this paper to accelerate the process of transcoding videos into H.264with arbitrary rate spatial resolution down-scaling. The proposed algorithm consists of three steps. F... A fast mode decision algorithm is proposed in this paper to accelerate the process of transcoding videos into H.264with arbitrary rate spatial resolution down-scaling. The proposed algorithm consists of three steps. First, an early-stop technique is introduced to determine the 16× 16-mode blocks, which take up about 70% of all the macroblocks; then, a bottom-up merging process is performed to determine the mode of rest non-early-stopped blocks; and then, we adopt half-pixel motion estimation to further refine the acquired predictive motion vectors. In order to obtain the predictive motion vectors for early-stop and merging processes, we propose a motion vector composition scheme, which can reuse the information in the input pre-encoded videos to handle the spatial resolution down-scaling. Experimental results showed that our algorithm is about four times faster than the Cascaded-Decoder-Encoder method and has negligible PSNR drop and little bit rate increase. 展开更多
关键词 Transcoding h.264 Mode decision Motion composition
下载PDF
RATE CONTROL ALGORITHM FOR H.264 VIDEO ENCODER 被引量:2
10
作者 Xue Jinzhu Shen Lansun (Signal & Information Processing Lab, Beijing University of Technology, Beijing 100022) 《Journal of Electronics(China)》 2003年第6期456-460,共5页
This letter proposes a rate control algorithm for H.264 video encoder, which is based on block activity and buffer state. Experimental results indicate that it has an excellent performance by providing much accurate b... This letter proposes a rate control algorithm for H.264 video encoder, which is based on block activity and buffer state. Experimental results indicate that it has an excellent performance by providing much accurate bit rate and better coding efficiency compared with H.264. The computational complexity of the algorithm is reduced by adopting a novel block activity description method using the Sum of Absolute Difference (SAD) of 16× 16 mode, and its robustness is enhanced by introducing a feedback circuit at frame layer. 展开更多
关键词 Rate control Video coding h.264
下载PDF
Fast motion estimation algorithm for H.264/AVC based on centered prediction 被引量:1
11
作者 Wei Zhou Zhemin Duan Hongqi Hu 《Journal of Systems Engineering and Electronics》 SCIE EI CSCD 2010年第6期1103-1110,共8页
H.264/AVC video coding standard can achieve roughly half of the bit-savings over MPEG2 and MPEG4 for a given quality. However, this comes at a cost in considerably increased complexity at the encoder and thus increase... H.264/AVC video coding standard can achieve roughly half of the bit-savings over MPEG2 and MPEG4 for a given quality. However, this comes at a cost in considerably increased complexity at the encoder and thus increases the difficulty in hardware implementation. The high redundancy that exists between the successive frames of a video sequence makes it possible to achieve a high data compression ratio. Motion estimation (ME) plays an important role in motion compensated video coding. A fast motion estimation algorithm for H.264/AVC is proposed based on centered prediction, called centered prediction based fast mixed search algorithm (CPFMS). It makes use of the spatial and temporal correlation in motion vector (MV) fields and feature of all-zero blocks to accelerate the searching process. With the initialized searching point prediction, adaptive search window changing and searching direction decision, CPFMS is provided to reduce computation in block-matching process. The experimental results show that the speed of CPFMS is nearly 12 times of FS with a negligible peak signal-noise ratio (PSNR) loss. Also, the efficiency of CPFMS outperforms some popular fast algorithms such as hybrid unsymmetrical cross multi-hexagongrid search and a novel multidirectional gradient descent search evidently. 展开更多
关键词 h.264/AVC motion estimation motion vectors early termination.
下载PDF
h-Said-Ball基与h-Said-Ball曲线
12
作者 刘婉柔 解滨 韩力文 《高校应用数学学报(A辑)》 北大核心 2024年第3期273-290,共18页
h-Bezier曲线是Bezier曲线基于h-微积分意义下的推广模型.为增强Said-Ball曲线的造型能力,提高h-Bezier曲线递归求值速度,该文提出任意次的h-Said-Ball基函数,构造了h-Said-Ball曲线.通过分析Said-Ball曲线递归求值算法与Bezier曲线的... h-Bezier曲线是Bezier曲线基于h-微积分意义下的推广模型.为增强Said-Ball曲线的造型能力,提高h-Bezier曲线递归求值速度,该文提出任意次的h-Said-Ball基函数,构造了h-Said-Ball曲线.通过分析Said-Ball曲线递归求值算法与Bezier曲线的转化关系,结合h-Bezier曲线的递归求值算法和h-Bernstein基函数的构造方式,得到任意次h-Said-Ball基函数的表达式.h-Said-Ball基具有非负,单位分解,端点插值等优良性质,和h-Bernstein基之间存在显式转换矩阵.进一步,定义h-Said-Ball曲线并分析其基本性质,推导递归求值算法和包络表示,h-Said-Ball曲线的求值计算量是h-Bezier曲线的一半.借助从h-Said-Ball曲线到h-Bezier曲线的割角算法,证明了h-Said-Ball基是全正基,从而h-Said-Ball曲线具有变差缩减性和保凸性.数值实例显示了h-Said-Ball曲线相比Said-Ball曲线的造型优势和灵活性. 展开更多
关键词 h-Bezier曲线 SAID-BALL曲线 h-Said-Ball基函数 h-Said-Ball曲线 全正基 递归求值算法
下载PDF
New Fragile Watermarking Technique to Identify Inserted Video Objects Using H.264 and Color Features
13
作者 Raheem Ogla Eman Shakar Mahmood +1 位作者 Rasha I.Ahmed Abdul Monem S.Rahma 《Computers, Materials & Continua》 SCIE EI 2023年第9期3075-3096,共22页
The transmission of video content over a network raises various issues relating to copyright authenticity,ethics,legality,and privacy.The protection of copyrighted video content is a significant issue in the video ind... The transmission of video content over a network raises various issues relating to copyright authenticity,ethics,legality,and privacy.The protection of copyrighted video content is a significant issue in the video industry,and it is essential to find effective solutions to prevent tampering and modification of digital video content during its transmission through digital media.However,there are stillmany unresolved challenges.This paper aims to address those challenges by proposing a new technique for detectingmoving objects in digital videos,which can help prove the credibility of video content by detecting any fake objects inserted by hackers.The proposed technique involves using two methods,the H.264 and the extraction color features methods,to embed and extract watermarks in video frames.The study tested the performance of the system against various attacks and found it to be robust.The evaluation was done using different metrics such as Peak-Signal-to-Noise Ratio(PSNR),Mean Squared Error(MSE),Structural Similarity Index Measure(SSIM),Bit Correction Ratio(BCR),and Normalized Correlation.The accuracy of identifying moving objects was high,ranging from 96.3%to 98.7%.The system was also able to embed a fragile watermark with a success rate of over 93.65%and had an average capacity of hiding of 78.67.The reconstructed video frames had high quality with a PSNR of at least 65.45 dB and SSIMof over 0.97,making them imperceptible to the human eye.The system also had an acceptable average time difference(T=1.227/s)compared with other state-of-the-art methods. 展开更多
关键词 Video watermarking fragile digital watermark copyright protection moving objects color image features h.264
下载PDF
A Fast quarter-pixel motion estimation algorithm for H.264/AVC 被引量:3
14
作者 CHEN Gang,JIA Zhen-hong,and CHEN He School of Information Science and Engineering, Xinjiang University, Urumqi 830046, China 《Optoelectronics Letters》 EI 2008年第1期66-68,共3页
A fast quarter-pixel motion estimation algorithm is proposed in this paper. The proposed algorithm based on mathematical models of the motion compensated prediction errors. Unlike conventional quarter-pixel accurate m... A fast quarter-pixel motion estimation algorithm is proposed in this paper. The proposed algorithm based on mathematical models of the motion compensated prediction errors. Unlike conventional quarter-pixel accurate motion estimation algorithm, proposed algorithm can avoid fractional-pixel interpolation and subsequent fractional-pixel search after integer-precision motion estimation. Experiments show that the proposed algorithm greatly reduces the computational complexity of quarter- pixel motion estimation, while keeping the nearly equal quality of the 展开更多
关键词 四分之一像素运动估计算法 数学模型 h.264/AVC 图像信号处理
下载PDF
A MV-Based Steganographic Algorithm for H.264/AVC without Distortion 被引量:1
15
作者 Hongqiong Tang Xiaoyuan Yang +1 位作者 Yingnan Zhang Ke Niu 《Computers, Materials & Continua》 SCIE EI 2020年第6期1205-1219,共15页
H.264/AVC video is one of the most popular multimedia and has been widely used as the carriers of video steganography.In this paper,a novel motion vector(MV)based steganographic algorithm is proposed for the H.264/AVC... H.264/AVC video is one of the most popular multimedia and has been widely used as the carriers of video steganography.In this paper,a novel motion vector(MV)based steganographic algorithm is proposed for the H.264/AVC compressed video without distortion.Four modules are introduced to eliminate the distortion caused by the modifications of motion vectors and guarantee the security of the algorithm.In the embedding block,the motion vector space encoding is used to embed a(2n+1)-ary notational number into an n-dimension vector composed of motion vectors generated from the selection block.Scrambling is adopted to disturb the order of steganographic carriers to improve the randomness of the carrier before the operation of embedding.The re-motion compensation(re-MC)block will re-construct the macroblock(MB)whose motion vectors have been modified by embedding block.System block plays the role of the generator for chaotic sequences and encryptor for secret data.Experimental results demonstrate that our proposed algorithm can achieve high embedding capacity without stego video visual quality distortion,it also presents good undetectability for existing MV-based steganalysis feature.Performance comparisons with other existing algorithms are provided to demonstrate the superiority of the proposed algorithm. 展开更多
关键词 Video steganography motion vector without distortion h.264/AVC
下载PDF
Fast Inter Coding Mode Selection Algorithm for H.264
16
作者 董海燕 张其善 《Chinese Journal of Aeronautics》 SCIE EI CAS CSCD 2006年第3期219-224,共6页
In order to reduce the encoding complexity of macroblock coding mode decision in H.264/AVC, a selective smaller block-size searching algorithm and a selective intra coding mode searching algorithm are proposed by usin... In order to reduce the encoding complexity of macroblock coding mode decision in H.264/AVC, a selective smaller block-size searching algorithm and a selective intra coding mode searching algorithm are proposed by using the high correlation among coding modes and in spatial and temporal domains of video sequence. Simulation results demonstrate that the proposed algorithm can provide significant improvement in computational requirement, with negligible small picture quality degradation and slight bit rate increase. 展开更多
关键词 h.264 video coding motion estimation inter flame coding intra frame coding mode decision rate distortion
下载PDF
Improved Diamond Search Algorithm for H.264/AVC Video Coding Standard
17
作者 HU Feng LIU Jia CHEN Shuzhen 《Wuhan University Journal of Natural Sciences》 CAS 2008年第1期62-66,共5页
Diamond search (DS) is an excellent fast block matching motion estimation (BMME) algorithm. In this paper, we propose an improved diamond search (IDS) algorithm, which revises the two search patterns of DS. The ... Diamond search (DS) is an excellent fast block matching motion estimation (BMME) algorithm. In this paper, we propose an improved diamond search (IDS) algorithm, which revises the two search patterns of DS. The proposed algorithm is compared with several mainstream algorithms. The simulation results show that the proposed algorithm over DS can be up to 20% gain on speedup on average, while maintain the similar or even better quality, both objectively and subjectively. The proposed algorithm is also competitive with other fast algorithms. 展开更多
关键词 diamond search h.264 motion estimation peak signal to noise ratio
下载PDF
Edge Feature Based Fast Mode Decision Algorithm for H.264 Intra Prediction
18
作者 高伟 李华 +2 位作者 张淑芳 侯玲 张树军 《Transactions of Tianjin University》 EI CAS 2006年第5期383-386,共4页
A fast intra mode decision algorithm is proposed in this paper to reduce the complexity of H. 264 encoder. The proposed algorithm adopted the pre-processing method based on edge feature in pictures to filter out some ... A fast intra mode decision algorithm is proposed in this paper to reduce the complexity of H. 264 encoder. The proposed algorithm adopted the pre-processing method based on edge feature in pictures to filter out some impossible prediction modes. Context information and pre-computed threshold are used to determine whether it is necessary to check the DC mode. This method is able to get rid of most of candidate modes so that only 66--150 modes are left for the final mode decision, instead of 592 modes in the case of full search (FS) method of H. 264. Simulation results demonstrate that the coding time of the proposed algorithm falls down 71.7% compared with FS method, while the performance loss is trivial compared with FS mode decision scheme. 展开更多
关键词 h. 264 fast mode decision intra prediction
下载PDF
H.264 MOTION ESTIMATION ALGORITHM BASED ON VIDEO SEQUENCES ACTIVITY
19
作者 Hu Weiwei Zhang Qishan 《Journal of Electronics(China)》 2008年第1期125-128,共4页
Motion estimation is an important part of H.264/AVC encoding progress, with high com- putational complexity. Therefore, it is quite necessary to find a fast motion estimation algorithm for real-time applications. The ... Motion estimation is an important part of H.264/AVC encoding progress, with high com- putational complexity. Therefore, it is quite necessary to find a fast motion estimation algorithm for real-time applications. The algorithm proposed in this letter adjudges the macroblocks activity degree first; then classifies different video sequences, and applies different search strategies according to the result. Experiments show that this method obtains almost the same video quality with the Full Search (FS) algorithm but with reduced more than 95% computation cost. 展开更多
关键词 Motion estimation Block matching Diamond search h.264
下载PDF
基于改进GA优化的级联H桥APF神经网络电流跟踪控制
20
作者 沈建强 邢砾云 +1 位作者 李冉 王策 《电力电容器与无功补偿》 2024年第2期63-70,共8页
针对基于级联H桥有源滤波器实现谐波抑制时,传统PI控制电流跟踪的抗扰性差以及由于神经网络预测的局域最优造成的电流跟踪预测不准确、延迟大等问题。本文提出了一种改进GA优化的级联H桥APF神经网络电流跟踪控制策略,以改进选择和交叉... 针对基于级联H桥有源滤波器实现谐波抑制时,传统PI控制电流跟踪的抗扰性差以及由于神经网络预测的局域最优造成的电流跟踪预测不准确、延迟大等问题。本文提出了一种改进GA优化的级联H桥APF神经网络电流跟踪控制策略,以改进选择和交叉操作的GA优化神经网络变化因子,提升了预测控制的全局搜索能力和鲁棒性能。仿真验证表明,所提出的控制策略相较于传统PI控制,提升了电流跟踪控制的鲁棒性;相较基于传统GA优化的神经网络控制方法,本文提出的方法跟踪速度提升了约0.04 s,控制误差减小约0.2 A,谐波畸变率降低0.36%。可见,响应速度和控制精度更优,具有更好的跟踪控制能力。 展开更多
关键词 级联h 有源电力滤波器 遗传算法 神经网络控制 电流跟踪
下载PDF
上一页 1 2 238 下一页 到第
使用帮助 返回顶部