H.264/AVC帧层码率控制算法的改进

为了提高码率控制在视频编码中的性能,本文提出了一种新的帧层R-Q码率控制算法模型。该模型直接通过H.264码率进行量化控制,但没有考虑复杂度测量估计,从一定程度上提高了码率控制的准确性。通过大量的理论推导与实验验证,提出的模型明显提高了峰值信噪比(P S N R),提高了图像的质量。     

一种基于分层B帧架构的高效比特分配算法

随着分层B帧码率控制技术在SVC(可伸缩视频编码)中的广泛应用,视频编码的质量得到了很大提高,然而传统的H.264码率控制技术并未将B帧的比特分配考虑在内。提出一种基于分层B帧架构自适应调节B帧比特分配的码率控制算法,该算法研究了基于同一个图像组(GoP)中各时域层权重因子的自适应调节,为各时域层分配不同的目标比特;同时基于同一个时域层中各帧复杂度的不同,为各帧分配不同的目标比特。实验结果表明,与目前流行的分层B帧码率控制算法相比,该算法在比特控制误差并未降低的情况下,客观质量PSNR可提高0.1～0.4 dB。     

基于ρ域线性率失真模型的H.264帧级码率控制算法1

本文基于ρ域线性率失真模型提出一种适用于H.264的帧级码率控制算法.先验证线性率失真函数对H.264编码算法的适用性,再通过使用混合自适应估计方法精确地估计出该模型惟一的参数θ,实现线性率失真函数在H.264码率控制中的应用.仿真结果表明,与JVT-H017算法相比,新算法不仅获得更精确的码率控制,而且获得更平稳的输出码率和PSNR,同时实现简单,适用于实时视频通信.     

基于H．264的宏块级码率控制算法

基于H．264码率控制算法的研究,考虑到图像中各宏块之间的差异,提出了宏块级的码率控制算法。实验结果表明,与JVT-G012提案相比,该方法在准确控制码率的同时,图像的视觉质量也有一定的提高。     

基于帧间信息度优化的H.264码率控制算法

基于视频编码标准H.264提出一种改进的码率控制算法.该算法优化了标准中原算法码率分配趋于平均而且不充分利用已编码帧信息的问题.由于引入了帧的信息度因子,使得码率分配更加准确,根据已编码帧的历史信息更准确地调整当前帧要使用的量化参数.实验结果表明:视频输出序列的峰值信噪比有明显提高,对视频传输取得了更好的码率控制效果.     

基于图像差分的H.264快速帧间模式选择算法

为提高H.264编码速度,提出一种快速帧间模式选择算法。以图像差分作为度量图像运动细致程度的标准,直接选出最佳帧间模式,避免不断计算每种帧间模式进行比较。实验结果表明,与原有算法相比,在没有损失图像码率和PSNR的情况下,帧间预测时间缩减了75%,实现了在H.264的D1图像实时编码。     

一种改进的基于柯西模型的H.264码率控制方法

H.264/AVC编码中的码率控制是通过有效控制输出码流的码率来提高其压缩视频质量的重要技术。本文基于H.264/AVC中的JVT-H017码率控制方案提出了一种改进算法。新算法根据H.264中DCT系数的分布特征,将柯西分布引入到码率控制模块,用更精确的柯西率失真模型取代了原先的二次率失真模型。在此基础上,进一步引入了一种联合PSNR比率和MAD比率进行图像复杂度预测的方法,并依此来调整帧级比特的分配和量化参数,克服了在出现复杂运动或场景切换时,因视频序列相邻帧之间相关性降低而导致的MAD预测失准的情况。实验结果表明,与JVT-H017方案及文献[5]中的算法比较,新的算法不仅具有更精确的码率控制,而且明显改善了输出码率的平稳性及重建图像的PSNR。      

基于时空预测模型的视频码率控制算法

针对传统视频图像码率控制算法不能很好地支持视频内容变化或者场景切换应用问题,提出一种基于时空预测模型的视频码率控制算法.该算法根据视频图像压缩时基于空间关联与时间关联的预测属性,引入人体视觉感知模型,通过对时间通道中的视频内容进行理解,采用视频图像帧间绝对误差均值(Mean Absolute Deviation,MAD)的方差来表征视频图像在时间通道中的运动趋势,评估当前视频图像帧内容复杂度并预测出MAD值;在此基础上,通过时空关联因子对MAD的预测值进行矫正,使得码率控制算法中关键参数MAD值能更好地贴合实际情况.实验证明,采用时空维度分析的码率控制算法更科学、更精准.     

一种H.264视频编码码率控制方法

根据视频编码线性率失真函数和对H．264整数变换量化方法分析，提出一种适合于H．264编码算法的码率控制算法。先验证线性率失真函数对H．264编码算法的适用性，再通过将H．264整数变换的量化分解为系数校正和统一量化两个步骤实现了线性率失真函数在H．264码率控制中的应用。实验证明，与JVT—G012码率控制算法相比，码率控制的准确性和信噪比均有所提高。     

一种改进比特分配的H．264／AVC码率控制算法

提出了一种新的改进的H．264／AVC码率控制算法,克服了MAD不能客观、准确的反映出整个图像的复杂度的问题,引入了一个新的MADMV参数,使包括纹理比特和头比特的图像复杂度得到准确的预测。实验结果表明,与JVT-G012相比,该方法可以在准确控制码率的同时,图像的视觉质量也有相应的提高。     

基于三维递归搜索的多级运动估计视频帧率上转换算法

运动补偿插帧是目前主要的帧率上转换方法。为减小内插帧中的块效应,并降低运算量以满足实时高清视频应用,该文提出了一种基于3维递归搜索(3-D Recursive Search, 3-D RS)的多级块匹配运动估计视频帧率上转换算法。该算法将3-D RS与双向运动估计相结合,首先对序列中相邻帧进行由粗到精的三级运动估计,再利用简化的中值滤波器平滑运动矢量场,最后通过线性插值补偿得到内插帧。实验结果表明,与现有的运动补偿插帧算法相比,该算法内插帧的主、客观质量都有所提高,且算法复杂度低,有很强的实用性。     

A multistage motion vector processing method for motion-compensated frame interpolation.

In this paper, a novel, low-complexity motion vector processing algorithm at the decoder is proposed for motion-compensated frame interpolation or frame rate up-conversion. We address the problems of having broken edges and deformed structures in an interpolated frame by hierarchically refining motion vectors on different block sizes. Our method explicitly considers the reliability of each received motion vector and has the capability of preserving the structure information. This is achieved by analyzing the distribution of residual energies and effectively merging blocks that have unreliable motion vectors. The motion vector reliability information is also used as a prior knowledge in motion vector refinement using a constrained vector median filter to avoid choosing identical unreliable one. We also propose using chrominance information in our method. Experimental results show that the proposed scheme has better visual quality and is also robust, even in video sequences with complex scenes and fast motion.     

应用于LCD控制器的动态抖动算法及帧速率控制技术

文章提出了应用于液晶显示(LCD)控制器的动态抖动算法及帧速率控制技术。抖动算法极大的改善了显示图象的平滑度，帧速率控制技术大大增加图象灰度而明显降低图象的抖动和赝象。结果显示在LCD控制器中采用动态抖动算法及帧速率控制技术，如果每一象素数据的位宽是8比特，则单色图象的显示效果可高达256级灰度，彩色图象高达256^3彩色。     

Arbitrary Frame Rate Transcoding Through Temporal and Spatial Complexity

In this paper, an arbitrary frame rate transcoding joint considering temporal and spatial complexity of frames in the adaptive length sliding window is proposed. The length of a sliding window can be adjusted according to bandwidth variation in order to decide the number of skipped frames. The proposed method preserves significant frames and drops non-significant ones using the complexity measurements. Moreover, the motion vector composition algorithm is proposed to reduce the computations of motion estimation process by adopting the coding feature of variable block sizes in H.264/AVC video transcoder. Experimental results show that the proposed method achieves higher visual quality compared to other existing methods. After combining with the proposed fast motion composition algorithm, our proposed algorithm reduces encoding time significantly with slight visual quality degradation.      

一种基于视觉显著度模型的无线视频码率控制算法(英文)

In order to further improve the efficiency of video compression, we introduce a perceptual characteristics of Human Visual System (HVS) to video coding, and propose a novel video coding rate control algorithm based on human visual saliency model in H.264/AVC. Firstly, we modifie Itti's saliency model. Secondly, target bits of each frame are allocated through the correlation of saliency region between the current and previous frame, and the complexity of each MB is modified through the saliency value and its...     

基于双树复小波变换的彩色视频水印算法

本文利用双树复小波变换(DTCWT)的多方向选择性和平移不变性,结合人眼视觉特征和MPEG运动编码原理,分析视频纹理复杂的运动区域来嵌入水印。仿真实验结果表明,该算法在抵抗加性Gaussian噪声、高压缩比的MPEG压缩编码、帧重组、帧平均和丢帧等攻击方面具有很好的鲁棒性。     

Frame-level bit allocation based on incremental PID algorithm and frame complexity estimation

Since the current rate control schemes in H.264 do not have the capability of efficient frame-level bit allocation, the video quality varies significantly from frame to frame especially for sequences with sudden scene changes or high motion activities. To overcome the limitation of frame-level bit allocation, we improve H.264 rate control scheme using two tools, the incremental proportional–integral–differential (PID) algorithm and the frame complexity estimation. The incremental PID algorithm is first introduced to control the buffer and reduce the influence of the buffer abrupt fluctuation in the process of frame-level bit allocation. To reduce more video quality variations, the frame target bit allocation is also adjusted by frame complexity that is estimated by residual energy. Simulation results show that the proposed rate control scheme, without introducing expensive computational complexity, decreases the average standard deviation of video quality by 32.29%.     

一种整帧丢失时的视频差错掩盖算法

压缩视频对于信道误码十分敏感,可导致重组视频的质量严重下降。在低码率的情况下,当网络传输中数据包丢失时,通常对应于一整帧图像内容的丢失。为了恢复丢失帧,提出了一种针对整帧图像丢失时的基于运动向量外推法的空时域相结合的差错掩盖算法。试验结果表明,该算法不仅能够恢复整个丢失帧,而且在主观上与客观上其掩盖效果均优于传统的掩盖算法。     

高速密集视频目标场景下的运动分析

本文首先分析了高速、密集图像目标场景下邻帧差分运动检估计检测法的缺陷.然后综合图像能量、高阶统计量预测理论以及块处理技术,对高速密集图像序列进行快速背景重建、运动区域提取与运动分析.基于DSP的平台测试表明:本文背景重建算法速度快,运动区域检测精度高,目标跟踪准确.为密集、高速的图像目标跟踪系统的研制提供了新的可借鉴方法.     

Asymptotic trajectory tracking of manipulators using uncalibrated visual feedback

To implement a position-based visual feedback controller for a manipulator, it is necessary to calibrate the homogeneous transformation matrix between its base frame and the vision frame besides intrinsic parameters of the vision system. The accuracy of such a calibration greatly affects the control performance. Substantial efforts must be made to obtain a highly accurate transformation matrix. In this paper, we propose an adaptive visual feedback controller for manipulators when the homogeneous transformation matrix is not calibrated. It is assumed that the vision system can measure the 3D position and orientation of the manipulator in real-time. Based on an important observation that the unknown transformation matrix can be separated from the visual Jacobian matrix, we propose an adaptive algorithm, similar to the model-based adaptive algorithm, to estimate the unknown matrix online. The use of the proposed visual feedback controller greatly simplifies the implementation of a manipulator-vision workcell. This controller is especially useful when such a pre-calibration is not possible. It is proved by Lyapunov approach that the motion of the manipulator approaches asymptotically to the desired trajectory. Simulations and experimental results are included to demonstrate performance of this adaptive visual feedback controller.