共查询到20条相似文献，搜索用时 15 毫秒
1.
WU Jing YE Xiu-qing GU Wei-kang 《浙江大学学报(A卷英文版)》2007,8(6):841-848
This paper proposes a new adaptive post-filtering algorithm to remove coding artifacts in block-based video coder. The proposed method concentrates on blocking and ringing artifacts removal. For de-blocking, the blocking strength is identified to determine the filtering range, and the maximum quantization parameter of the image is used to adapt the 1D fuzzy filter. For de-ringing, besides the edge detection, a complementary ringing detection method is proposed to locate the neglected ringing blocks, and the gradient threshold is adopted to adjust the parameter of 2D fuzzy filter. Experiments are performed on the MPEG-4 sequences. Compared with other methods, the proposed one achieves better detail preservation and artifacts removal performance with lower computational cost. 相似文献
2.
3.
Frame skipping in low bit video coding could significantly reduce the visual quality of reconstructed video. At the same time, if the complexity of the video sequence remains high for a long period, then driving up the long term average bit rate, the only resort of MPEG-4 Q2 rate control algorithm results in using a high quantization scale, which shows a poor visual quality of the reconstructed video. This paper analyzes the main causes of frame skipping in current MPEG-4 frame rate control scheme, and presents a new rate control algorithm based on the quadratic R-D model over a CBR channel. Key features of the present work are. 1) the bits allocated to each P-frame or B-frame are in proportion to its distance from the end of this GOP, i.e. more bits are allocated to the frames that are nearer to their reference Ⅰ -frame: 2) the target buffer level is changeable in the GOP, at the end of each GOP( five P-frames or B-frames), the target buffer level is linearly reduced from 1/2 to 1/4 of buffer size, to other frames, the target buffer level is set to 1/2 of buffer size: 3 ) a selective and judicious use of the reduced resolution mode, in addition to a modulation of the quantization scale parameter, is to control the average long term bit rate. Experimental results with different video sequences of varied complexity, encoded at low bit rates show better efficacy of the proposed algorithm than MPEG-4 Q2 rate control scheme, and the experimental results also show that the improved algorithm has significantly reduced the number of frame skipping, increased the overall PSNR, and improved the perceptual quality. 相似文献
4.
Frame loss error concealment for SVC 总被引：2，自引：0，他引：2
INTRODUCTION Real-time transmission of video data in network environments, such as wireless and Internet, is a challenging task, as it requires coding efficiency, network friendliness and error robustness. Scalability is a possible solution for network adaptive applica- tions. The Scalable Extension of H.264/AVC (SVC) (JVT of ISO/IEC MPEG & ITU-T VCEG, 2005b) aims at achieving both high compression performance and adaptivity for video delivery over heterogeneous networks. SVC… 相似文献
5.
在电力数据采集终端中滤波器常用来滤除耦合在电力信号传输线路上的高频谐波、抑制干扰,以确保有效地采集电力线上的电压和电流信号,提高系统的采样精度．本文提出一种新的混合滤波方案,即采用二阶压控电压源低通滤波电路的硬件滤波和去极值平均魔波与维纳滤波相结合的数字滤波方案,采用硬件滤波滤除采集信号中的高频分量,通过软件滤波抑制低频分量中的干扰．实验结果表明,这种方案可行且能达到预期的效果． 相似文献
6.
KIM Yong-deak 《浙江大学学报(A卷英文版)》2006,7(5):857-863
INTRODUCTION With the expansion of multimedia applications, video transmission is becoming an important issue in the research area of communication. It is very im- portant to compress a large amount of video data effectively, which has already attracted considerable attention recently. To make source coders both er- ror-resilient and network-adaptive are two main challenges facing the video compression techniques. It is necessary to make the bitstreams temporal, spa- tial and SNR scalabl… 相似文献
7.
武英 《南京晓庄学院学报》2009,25(3):86-89
在已有极值中值的滤波算法的基础上,提出一种自适应滤波算法.该算法对于不同椒盐噪声密度采用不同滤波方法,在噪声密度较低时,采用同时考虑灰度差值和空间距离的自适应权重函数进行滤波,在噪声密度较大时,采用递归方式进行均值滤波.实验证明,该算法在滤除椒盐噪声能力、细节保护能力方面均有较大提高. 相似文献
8.
With the development of general-purpose processors (GPP) and video signal processing algorithms, it is possible to implement a software-based real-time video encoder on GPP, and its low cost and easy upgrade attract developers' interests to transfer video encoding from specialized hardware to more flexible software. In this paper, the encoding structure is set up first to support complexity scalability; then a lot of high performance algorithms are used on the key time-consuming modules in coding process; finally, at programming level, processor characteristics are considered to improve data access efficiency and processing parallelism. Other programming methods such as lookup table are adopted to reduce the computational complexity. Simulation results showed that these ideas could not only improve the global performance of video coding, but also provide great flexibility in complexity regulation. 相似文献
9.
Asymmetric stereoscopic video coding can take advantage of binocular suppression in human vision by representing one of the two views in lower quality.This paper proposes a bit allocation strategy for asymmetric stereoscopic video coding.In order to improve the accuracy of bit allocation and rate control in the left view,a proportionalintegral-derivative controller is adopted.Meanwhile,to control the quality fluctuation between consecutive frames of the left view,a quality controller is adopted.Besides,a fuzzy controller is proposed to control the variation in quality between the left and right views by comparing the PSNR disparity of two views with a fixed threshold,which is used to quantize the binocular psycho-visual redundancy and adjust the quantization parameter (QP) of the right view correspondingly.The proposed algorithm has been implemented in H.264/AVC video codec,and the experimental results show its effectiveness in rate control while keeping a good quality for the left view,and fewer bits are allocated for the right view so that the overall bit rate is saved by 7.2% at most without the loss of subjective visual quality for stereoscopic video. 相似文献
10.
INTRODUCTION Modern videoconferencing systems allow two o more participants to communicate with each other in real-time using both audio and video. Conventionally when more than two participants are present, a sta configuration is generally employed, wherein a Mul tipoint Conferencing Unit (MCU), or bridge, is util ized to connect to all participants and coordinat communications between them. The general archi tecture is shown in Fig.1. Fig.1 Multipoint videoconferencing system Network… 相似文献
11.
高斯型拉普拉斯（LoG）算子采用高斯滤波器平滑图像。高斯滤波器需要控制截止频率来改变滤波的效果,本文主要分析高斯低通滤波器和LoG算子的各种特点,通过计算机模拟来分析含噪声图像的滤波后对LoG算子边缘检测的影响。 相似文献
12.
在AD转换中利用32位ARM单片机的硬件乘法器实现低通滤波;此种滤波方法包括算法确定、定点表示方式以及如何利用乘法器实现;利用MATLAB对滤波系统进行仿真及对结果的分析表明：采用此种滤波算法优点是更大限度地降低系统开销,提高程序效率。 相似文献
13.
本文提出了一种新的在MPEG-4编码过程中提高实时性的算法。算法采用双重筛选机制,充分利用了运动估计的结果提取运动对象。首先在运动估计过程中加入背景优先准则进行第一重筛选;然后根据运动估计后宏块的最小平均绝对差值分利用区域自适应门限进行第二重筛选,从而获得运动区域掩模;最后对掩模进行形态滤波和填充消除噪声点,最终得到运动区域。算法分别在硬件和软件平台上进行测试,结果表明提出的算法得到了理想的分割效果,较传统的在编码前进行运动对象提取的方法实时性大大提高了。 相似文献
14.
刘传文 《临沂师范学院学报》2007,29(3):95-96
将遗传算法应用于小波变换与矢量量化技术相结合的图像压缩编码中,提出了基于DWT和遗传算法的矢量量化图象压缩编码算法.研究表明,在相同压缩比下,这种算法较其它算法能更好地改善图像的质量. 相似文献
15.
杨维 《福建工程学院学报》2007,5(3):270-273
采用非线性滤波方法处理图像去噪问题时,阈值参数的选取和恰当使用滤波器函数,对去噪图像的效果影响极大。文章构造了可用于非线性滤波算法的一族分段次小波阈值参数滤波器函数,它是Donoho的软阈值滤波器函数的推广,证明了滤波后的逼近是Besov空间中泛函的近似最小值。该滤波器函数次数越大,逼近效果越好,也证明了广义软阈值滤波器函数的极限是一理想低通滤波器。仿真结果证实了区间双正交小波比Daubech ies小波有更好的去噪效果。 相似文献
16.
Low energy consumption is one of the main challenges for wireless video transmission on battery limited devices. The energy invested at the lower layers of the protocol stack involved in data communication, such as link and physical layer, represent an important part of the total energy consumption. This communication energy highly depends on the channel conditions and on the transmission data rate. Traditionally, video coding is unaware of varying channel conditions. In this paper, we propose a cross-layer approach in which the rate control mechanism of the video codec becomes channel-aware and steers the instantaneous output rate according to the channel conditions to reduce the communication energy. Our results show that energy savings of up to 30% can be obtained with a reduction of barely 0.1 dB on the average video quality. The impact of feedback delays is shown to be small. In addition, this adaptive mechanism has low complexity, which makes it suitable for real-time applications. 相似文献
17.
提出一种新型自适应图象细节保护滤波器．它从不同方向或不同区域对滤波象素点的灰度值进行估计,通过比较各估值的差异,判断是属于灰度均匀区还是属于细节区,以采取不同的滤波方法．该滤波器的计算量小,尤其适用于同时受高斯噪声和脉冲噪声污染的图象,其噪声滤除性能和细节保护能力优于多层中值滤波器． 相似文献
18.
Low energy consumption is one of the main challenges for wireless video transmission on battery limited devices. The energy invested at the lower layers of the protocol stack involved in data communication, such as link and physical layer, represent an important part of the total energy consumption. This communication energy highly depends on the channel conditions and on the transmission data rate. Traditionally, video coding is unaware of varying channel conditions. In this paper, we propose a cross-layer approach in which the rate control mechanism of the video codec becomes channel-aware and steers the instantaneous output rate according to the channel conditions to reduce the communication energy. Our results show that energy savings of up to 30% can be obtained with a reduction of barely 0.1 dB on the average video quality. The impact of feedback delays is shown to be small. In addition, this adaptive mechanism has low complexity, which makes it suitable for real-time applications. 相似文献
19.
Chen Guo-bin 《浙江大学学报(A卷英文版)》2006,7(1):13-18
The limitation of processing power, battery life and memory capacity of portable terminals requires reducing encoding complexity in mobile communications. Motion estimation (ME) is the most computationally intensive module in a typical video codec, which determines not only the encoder’s performance but also the reconstructed video quality. In this paper, a fast ME algorithm for H.264/AVC baseline profile coding is proposed based on the analysis of motion vector field and error surface, and the statistical distributions of different type macroblocks (MBs). Simulation results showed that: in comparison with MVFAST, the proposed algorithm can decrease the computational load over 7.2% with no requirement of expanding memory capacity while maintaining the same video quality as MVFAST. Furthermore, its simplicity makes it easy to be implemented on hardware. 相似文献
20.
叶轻舟 《福建工程学院学报》2004,2(2):168-171
基于利用电压型运算放大器(OUA)的主极点，设计单输入—多输出的电压模式全有源双二阶滤波器结构，这种结构通过直接选择不同的输出端，能实现低通、带通、高通滤波功能，且滤波器的参数可通过调节OTA的跨导增益来进行调节。 相似文献