基于纹理相似性的高效视频编码帧间预测优化算法

为了提高高效率视频编码(HEVC)的编码效率,该文对帧间预测算法进行优化,提出一种基于纹理相似性的快速深度判决算法。随着视频分辨率的提高,视频序列中的空域冗余也随之增加,HEVC通过增加编码块尺寸来提高预测效率,代价就是编码复杂度的急剧增加。通过对视频序列分析可知,图像中的平滑区域与细节区域在相邻帧中存在很大的相关性。该文利用相邻已编码帧的相邻编码块的深度信息,来快速判决当前待编码块的深度信息。对于平滑区域,快速判决待编码最大编码单元的最大深度,以减少小块编码单元的模式判决;对于细节区域,快速判决待编码最大编码单元的最小深度,以减少大块编码单元的模式判决。实验结果表明,与原始的HEVC算法相比,该文所提算法编码比特率平均增加约0.13%以内,PSNR的平均降幅为0.09 dB,算法运行时间平均减少了约50%。     

Gradient Fusion Method for Night Video Enhancement

To resolve video enhancement problems, a novel method of gradient domain fusion wherein gradient domain frames of the background in daytime video are fused with nighttime video frames is proposed. To verify the superiority of the proposed method, it is compared to conventional techniques. The implemented output of our method is shown to offer enhanced visual quality.     

YPbPr分量高清晰度视频分析仪的研制

自主研制了高清晰度视频分析仪,包括模拟前端、AD采集和主机接口在内的YPbPr分量高清晰度视频测试硬件平台和在此之上开发的高清视频测试软件,实现了1 920×1 080i@50 Hz,14 bit取样深度,74.25 Msample/s(兆采样/s)视频数据采集和4倍速PCI-E数据传输.经过与泰克TG700和VM6000的比对实验,证明自制样机的彩条测试不确定度为:2.0(1+8％) mV,达到了与VM6000以及NI 5124相近的技术指标.通过中间件的适配,本文研制的高清视频分析软件也移植到了NI5124平台上,实现了同样的视频测试功能.     

SH320大闭塞量低噪声视频放大器

本文介绍了ＳＨ３２０大闭塞量低噪声视频放大器的设计和研制。从对主要技术指标的分析入手，确定了合理的方案，并对电路进行了优化设计。在制作上，根据性能和结构要求，采用了高密度布线、多芯片组装的薄膜工艺。最后实现的是一种ＭＣＭ（多芯片组件）电路，在电性能上优于用户的要求，在工艺实现上也是采用ＭＣＭ技术的有益尝试。     

单片视频D／A转换器SDA1016的电路分析与设计

对单片视频Ｄ／Ａ转换器ＳＤＡ１０１６进行了电路原理分析和优化设计，该结果可作为电路研制及应用的参考。给出了ＳＤＡ１０１６视频ＤＡＣ的复合视频应用电路。采用了某些模拟技术，实现了ＳＤＡ１０１６全直流分析、子电路（块）的瞬态分析，是ＳＰＩＣＥ用于ＬＳＩ电路分析和优化设计的成功例证。     

Eliminating bandwidth estimation from adaptive video streaming in wireless networks

Dynamic Adaptive Streaming over HTTP (DASH) is the state-of-the-art technology for video streaming and has been widely deployed in both wired and wireless environments. However, mobile DASH users often suffer from video quality oscillation and even video freeze in wireless environments, which results in poor user experience. This is mainly because most quality adaptation algorithms in DASH rely highly on bandwidth estimation to adjust the video quality while wireless network bandwidth is unstable in nature and changes frequently according to wireless channel contention and condition. To provide stable performance, even during severe bandwidth fluctuation, this paper proposes the Wireless Quality Adaptation (WQUAD) algorithm, which eliminates bandwidth estimation from quality adaptation. Thanks to the Scalable Video Codec (SVC), the proposed scheme always prioritizes to lower layers over higher ones as long as the play-out buffer is not completely filled by the lower layers. As a result, the client always fills the buffer with the base layers first and then the upper enhancement layers sequentially. This horizontal adaptation is straightforward and does not require any bandwidth estimation. Through NS-2 simulations, we show that WQUAD achieves (i) stable performance, keeping the video quality level with respect to the long-term network bandwidth, (ii) effective video freeze prevention, and (iii) high video quality on average.     

Content-adaptive parameters estimation for multi-dimensional rate control

Multi-dimensional rate control schemes have been recently utilized to adapt video streams to dynamic network conditions and heterogeneous devices. However, current multi-dimensional rate control methods, which estimate the model coefficients using fixed update duration, usually yield inaccurate parameters for dynamically changing video content. To address this problem, a content-adaptive parameters estimation scheme is proposed for multi-dimensional rate control. Firstly, we propose to estimate the parameters using dynamical update duration based on video content and the update duration of the model coefficients is determined by jointly considering the varying picture complexity and feedback information from the actual encoding results, which can improve the model parameter estimation accuracy. Secondly, a coarse-to-fine initial parameter calculation method is proposed to refine the initial frame rate according to the channel condition and the video sequence characteristics. Extensive experimental results show that the proposed solutions outperform the state-of-the-art schemes, especially for video sequences with high temporal and spatial complexity. Furthermore, our algorithm also slightly reduces the computational complexity as compared to related algorithms.     

Low complexity encoder optimization for HEVC

High Efficiency Video Coding (HEVC) improved the coding efficiency significantly. Compared to its predecessor H.264/AVC, it can provide equivalent subjective quality with more than 57% bit rate reduction. However, the improvement on coding efficiency is obtained at the expense of much more intensive computation complexity. In this paper, based on an overall analysis of computation complexity at the HEVC encoder, a low complexity encoder optimization scheme is proposed by reducing the number of available candidates for evaluation in terms of the intra prediction mode decision, early termination of coding unit (CU) splitting and adaptive reference frame selection. With the proposed scheme, the rate distortion optimization (RDO) technique of HEVC can be implemented in a low-complexity way for complexity-constrained encoders. Experimental results demonstrate that, compared with the original HEVC reference encoder implementation, the proposed optimization scheme can achieve more than 40% complexity reduction on average with coding performance degradation as only 0.43% which can be ignorable.     

数字视频编码器用DDS的设计与实现

提出了一种应用于数字视频编码器中直接数字频率合成器（ＤＤＳ）的设计方案。通过优化调度策略,使内嵌ＲＯＭ阵列的大小仅为普通方法的八分之一。仿真结果表明该方法的相位误差为０．１５％,Ｐ,ＰＡＬ制式要求产生副载波信号的ＳＮＲ为６６ｄＢ,ＮＴＳＣ制式时的ＳＮＲ为６４ｄＢ。