Many modern video encoders use the Lagrangian rate-distortion optimization （RDO） algorithm for mode deci- sions during the compression procedure. For each encoding stage, this approach involves minimizing a cost, wh...Many modern video encoders use the Lagrangian rate-distortion optimization （RDO） algorithm for mode deci- sions during the compression procedure. For each encoding stage, this approach involves minimizing a cost, which is a function of rate, distortion and a multiplier called Lambda. This paper proposes to improve the RDO process by applying two modifications. The first modification is to increase the ac- curacy of rate estimation, which is achieved by computing a non-integer number of bits for arithmetic coding of the syntax elements. This leads to a more accurate cost computation and therefore a better mode decision. The second modification is to search and adjust the value of Lambda based on the char- acteristics of each coding stage. For the encoder used, this paper proposes to search multiple values of Lambda for the intra-4x4 mode decision. Moreover, a simple shift in Lambda value is proposed for motion estimation. Each of these modi- fications offers a certain gain in RDO performance, and, when all are combined, an average bit-rate saving of up to 7.0% can be achieved for the H.264/AVC codec while the same concept is applicable to the H.265/HEVC codec as well. The extra added complexity is contained to a certain level, and is also adjustable according to the processing resources available.展开更多
A fast motion estimation algorithm for variable block-size using the ＂line scan and block merge procedure＂ is proposed for airborne image compression modules.Full hardware implementation via FPGA is discussed in det...A fast motion estimation algorithm for variable block-size using the ＂line scan and block merge procedure＂ is proposed for airborne image compression modules.Full hardware implementation via FPGA is discussed in detail.The proposed pipelined architecture based on the line scan algorithm is capable of calculating the required 41 motion vectors of various size blocks supported by H.264 within a 16 × 16 block in parallel.An adaptive rate distortion cost function is used for various size block decision.The motion vectors of adjacent small blocks are merged to predict the motion vectors of larger blocks for reducing computation.Experimental results show that our proposed method has lower computational complexity than full search algorithm with slight quality decrease and little bit rate increase.Due to the high real-time processing speed it can be easily realized in hardware.展开更多
多视点视频编码(Multiview Video Coding,MVC)利用运动估计和视差估计取得了较好的编码性能,但在易错的网络环境下传输MVC视频码流,将导致差错在视点内与视点间进行扩散.针对多视点视频的编码特性,提出了一种端到端的失真度估计模型,并...多视点视频编码(Multiview Video Coding,MVC)利用运动估计和视差估计取得了较好的编码性能,但在易错的网络环境下传输MVC视频码流,将导致差错在视点内与视点间进行扩散.针对多视点视频的编码特性,提出了一种端到端的失真度估计模型,并将此模型与率失真优化相结合得到一种基于联合信源信道的编码模式选择算法.实验结果表明该方法能够在易错网络环境下有效的提高多视点视频的传输效率.展开更多
文摘Many modern video encoders use the Lagrangian rate-distortion optimization （RDO） algorithm for mode deci- sions during the compression procedure. For each encoding stage, this approach involves minimizing a cost, which is a function of rate, distortion and a multiplier called Lambda. This paper proposes to improve the RDO process by applying two modifications. The first modification is to increase the ac- curacy of rate estimation, which is achieved by computing a non-integer number of bits for arithmetic coding of the syntax elements. This leads to a more accurate cost computation and therefore a better mode decision. The second modification is to search and adjust the value of Lambda based on the char- acteristics of each coding stage. For the encoder used, this paper proposes to search multiple values of Lambda for the intra-4x4 mode decision. Moreover, a simple shift in Lambda value is proposed for motion estimation. Each of these modi- fications offers a certain gain in RDO performance, and, when all are combined, an average bit-rate saving of up to 7.0% can be achieved for the H.264/AVC codec while the same concept is applicable to the H.265/HEVC codec as well. The extra added complexity is contained to a certain level, and is also adjustable according to the processing resources available.
基金Supported by the Aviation Science Fund of China(2009ZC15001)
文摘A fast motion estimation algorithm for variable block-size using the ＂line scan and block merge procedure＂ is proposed for airborne image compression modules.Full hardware implementation via FPGA is discussed in detail.The proposed pipelined architecture based on the line scan algorithm is capable of calculating the required 41 motion vectors of various size blocks supported by H.264 within a 16 × 16 block in parallel.An adaptive rate distortion cost function is used for various size block decision.The motion vectors of adjacent small blocks are merged to predict the motion vectors of larger blocks for reducing computation.Experimental results show that our proposed method has lower computational complexity than full search algorithm with slight quality decrease and little bit rate increase.Due to the high real-time processing speed it can be easily realized in hardware.
文摘多视点视频编码(Multiview Video Coding,MVC)利用运动估计和视差估计取得了较好的编码性能,但在易错的网络环境下传输MVC视频码流,将导致差错在视点内与视点间进行扩散.针对多视点视频的编码特性,提出了一种端到端的失真度估计模型,并将此模型与率失真优化相结合得到一种基于联合信源信道的编码模式选择算法.实验结果表明该方法能够在易错网络环境下有效的提高多视点视频的传输效率.
