A screen content coding （SCC） algorithm that uses a primary reference buffer （PRB） and a secondary reference buffer （SRB） for string matching and string copying is proposed. PRB is typically the traditional reco...A screen content coding （SCC） algorithm that uses a primary reference buffer （PRB） and a secondary reference buffer （SRB） for string matching and string copying is proposed. PRB is typically the traditional reconstructed picture buffer which provides reference string pixels for the current pixels being coded. SRB stores a few of recently and frequently referenced pixels for repetitive reference by the current pixels being coded. In the encoder, searching of optimal reference string is performed in both PRB and SRB, and either a PRB or SRB string is selected as an optimal reference string on a string-by-string basis. Compared with HM-16.4＋SCM-40 reference software, the proposed SCC algorithm can improve coding performance measured by bit-distortion rate reduction of average 4.19% in all-intra configuration for text and graphics with motion category＇ of test sequences defined by JCT-VC common test condition.展开更多
1 IntroductionThe screen content coding （SCC） standard [1] for high efficiency video coding （HEVC） is an international standard specially developed for screen content.
传统无损压缩算法对屏幕图像的压缩效果不佳。该文根据典型屏幕图像的特性,以LZ4HC(LZ4 High Compression)算法为具体实现基础,提出一种基于串匹配的高性能低复杂度(String Matching with High Performance and Low Complexity,SMHPLC)...传统无损压缩算法对屏幕图像的压缩效果不佳。该文根据典型屏幕图像的特性,以LZ4HC(LZ4 High Compression)算法为具体实现基础,提出一种基于串匹配的高性能低复杂度(String Matching with High Performance and Low Complexity,SMHPLC)的屏幕图像无损压缩算法。相对于传统字典编码无损压缩算法,新算法提出了以像素为搜索和匹配单位,对未匹配串长度、匹配串长度以及匹配偏移量这3个编码参数进行联合优化编码,并对参数进行映射编码。实验结果表明,SMHPLC具有高性能和低复杂度的综合优势,大幅降低编码复杂度,提高了编码效率。使用移动的文字和图形类的AVS2通用测试序列作为测试对象,对于YUV和RGB两种格式,SMHPLC算法比LZ4HC总体节省码率分别为22.4%,21.2%,同时编码复杂度降低分别为35.5%,46.8%。展开更多
鉴于传统视频压缩算法对屏幕视频编码的效果不理想,提出了一种误差限自适应的有损字典编码方案,并和全色度HEVC有机融合,形成LDSC（Lossy Dual-coder Single Chroma-sampling-rate）算法.该算法根据屏幕内容中不同类型区域的编码特性,...鉴于传统视频压缩算法对屏幕视频编码的效果不理想,提出了一种误差限自适应的有损字典编码方案,并和全色度HEVC有机融合,形成LDSC（Lossy Dual-coder Single Chroma-sampling-rate）算法.该算法根据屏幕内容中不同类型区域的编码特性,自适应地选择率失真性能较好的编码结果放入码流.为了评价有损字典编码的性能,提出了基于匹配长度和匹配失真的LD-Cost（Length Distortion Cost）模型,并使用拉格朗日乘子法对模型进行分析和计算.对于有损字典编码过程中可能出现的误差积累现象,给出了可行的解决方案.实验结果表明,与基于无损字典编码的双编码器方案相比,在不损伤主观图像质量的前提下,LDSC算法能明显提高编码性能,对连续色调内容居多的屏幕视频也表现出更好的编码适应性,全Ⅰ帧配置下BD-rate性能比基于无损字典编码的方案提高了3％～15％,与单纯使用HEVC相比,BD-rate性能提高了7％～49％.展开更多
针对屏幕与混合内容视频具有多样性的特点,在我国第二代数字音视频编解码技术标准的屏幕与混合内容视频编码(the second-generation Audio Video Coding Standard Screen and Mixed Content Coding, AVS2-SMCC)扩展版中,提出了由一般串...针对屏幕与混合内容视频具有多样性的特点,在我国第二代数字音视频编解码技术标准的屏幕与混合内容视频编码(the second-generation Audio Video Coding Standard Screen and Mixed Content Coding, AVS2-SMCC)扩展版中,提出了由一般串模式、第一受限串模式和第二受限串模式三种受限串模式组成的通用串预测算法(Universal String Prediction, USP)及其关键技术,其主要部分已经被AVS2-SMCC扩展版工作草案3.0稿采纳.三种受限串模式统一采用偏移串、坐标串和不可预测像素串三种串类型之一或其组合来实现.当编码单元采用USP算法进行编码时,用三种受限串模式对其分别进行预编码,自适应采用三种受限串模式中取得率失真值最小的受限串模式对其进行编码.实验结果表明,对于AVS2-SMCC通用测试序列中移动的文字和图形类别,提出的USP算法与国际上最新的(High Efficiency Video Coding, HEVC)标准SMCC扩展版(High Efficiency Video Coding-Screen Content Coding, HEVC-SCC)相比,在编解码复杂度增加较少的情况下,对于有损全帧内配置 Y 分量、 U 分量、 V 分量平均BD - rate降低率分别可达23.2%、18.3%、19.4%,基于CPSNR的三分量综合的平均BD - rate降低率为22.1%,编码效率已经大幅超过HEVC-SCC.展开更多
基金supported in part by National Natural Science Foundation of China under Grant No.61201226 and 61271096Natural Science Foundation of Shanghai under Grant No.12ZR1433800Specialized Research Fund for the Doctoral Program under Grant No.20130072110054
文摘A screen content coding （SCC） algorithm that uses a primary reference buffer （PRB） and a secondary reference buffer （SRB） for string matching and string copying is proposed. PRB is typically the traditional reconstructed picture buffer which provides reference string pixels for the current pixels being coded. SRB stores a few of recently and frequently referenced pixels for repetitive reference by the current pixels being coded. In the encoder, searching of optimal reference string is performed in both PRB and SRB, and either a PRB or SRB string is selected as an optimal reference string on a string-by-string basis. Compared with HM-16.4＋SCM-40 reference software, the proposed SCC algorithm can improve coding performance measured by bit-distortion rate reduction of average 4.19% in all-intra configuration for text and graphics with motion category＇ of test sequences defined by JCT-VC common test condition.
基金supported in part by National Natural Science Foundation of China under Grant No.61201226 and 61271096Specialized Research Fund for the Doctoral Program under Grant No.20130072110054
文摘1 IntroductionThe screen content coding （SCC） standard [1] for high efficiency video coding （HEVC） is an international standard specially developed for screen content.
文摘传统无损压缩算法对屏幕图像的压缩效果不佳。该文根据典型屏幕图像的特性,以LZ4HC(LZ4 High Compression)算法为具体实现基础,提出一种基于串匹配的高性能低复杂度(String Matching with High Performance and Low Complexity,SMHPLC)的屏幕图像无损压缩算法。相对于传统字典编码无损压缩算法,新算法提出了以像素为搜索和匹配单位,对未匹配串长度、匹配串长度以及匹配偏移量这3个编码参数进行联合优化编码,并对参数进行映射编码。实验结果表明,SMHPLC具有高性能和低复杂度的综合优势,大幅降低编码复杂度,提高了编码效率。使用移动的文字和图形类的AVS2通用测试序列作为测试对象,对于YUV和RGB两种格式,SMHPLC算法比LZ4HC总体节省码率分别为22.4%,21.2%,同时编码复杂度降低分别为35.5%,46.8%。
文摘针对屏幕与混合内容视频具有多样性的特点,在我国第二代数字音视频编解码技术标准的屏幕与混合内容视频编码(the second-generation Audio Video Coding Standard Screen and Mixed Content Coding, AVS2-SMCC)扩展版中,提出了由一般串模式、第一受限串模式和第二受限串模式三种受限串模式组成的通用串预测算法(Universal String Prediction, USP)及其关键技术,其主要部分已经被AVS2-SMCC扩展版工作草案3.0稿采纳.三种受限串模式统一采用偏移串、坐标串和不可预测像素串三种串类型之一或其组合来实现.当编码单元采用USP算法进行编码时,用三种受限串模式对其分别进行预编码,自适应采用三种受限串模式中取得率失真值最小的受限串模式对其进行编码.实验结果表明,对于AVS2-SMCC通用测试序列中移动的文字和图形类别,提出的USP算法与国际上最新的(High Efficiency Video Coding, HEVC)标准SMCC扩展版(High Efficiency Video Coding-Screen Content Coding, HEVC-SCC)相比,在编解码复杂度增加较少的情况下,对于有损全帧内配置 Y 分量、 U 分量、 V 分量平均BD - rate降低率分别可达23.2%、18.3%、19.4%,基于CPSNR的三分量综合的平均BD - rate降低率为22.1%,编码效率已经大幅超过HEVC-SCC.
