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 th...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.展开更多
This paper for the first time proposes an empirical framework for inclusive growth, under which policy :s-efficiency and distributive impacts can both be assessed. This paper applies this framework to China :s-rural i...This paper for the first time proposes an empirical framework for inclusive growth, under which policy :s-efficiency and distributive impacts can both be assessed. This paper applies this framework to China :s-rural infrastructure and a large sample of individual-level data, providing estimates of growth and distributive impacts of physical infrastructures of telephone and tap water in rural China. They all are found to promote rural income growth, helping narrow the rural-urban gap in China. More importantly, the poorer gained more than the richer from these infrastructures, implying benign distributive effects. This paper sheds light on the positive and important role in which infrastructure plays to promote inclusive growth in rural China.展开更多
文摘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.
基金funded by Bairen Program of Yunnan provincethe NSF Projects 71133004 and 71603026 of the National Natural Science Foundation of China+1 种基金Projects 2015M580055 and 2016T90048 of the China Postdoctoral Science FoundationYouth Scholars Program of Beijing Normal University
文摘This paper for the first time proposes an empirical framework for inclusive growth, under which policy :s-efficiency and distributive impacts can both be assessed. This paper applies this framework to China :s-rural infrastructure and a large sample of individual-level data, providing estimates of growth and distributive impacts of physical infrastructures of telephone and tap water in rural China. They all are found to promote rural income growth, helping narrow the rural-urban gap in China. More importantly, the poorer gained more than the richer from these infrastructures, implying benign distributive effects. This paper sheds light on the positive and important role in which infrastructure plays to promote inclusive growth in rural China.
