| As the most important information transmission carrier,video has been widely used in people's daily life.As one of the important video applications,video surveillance plays a key role in the fields of intelligent security and safe campus in recent years.In a real-time video communication system,the bandwidth of the transmission channel is usually limited and time-varying.How to improve the quality of the video as much as possible while meeting the channel bandwidth limitation is a study problem that has received widespread attention.In order to solve this problem,the birth of each generation of video coding standards is accompanied by a complete set of rate control algorithms.The performance of the rate control algorithm directly affects the practicability of the video coding standard.With the rapid development of hardware technology and information processing technology,high-definition video has been popularized in video surveillance systems.In order to improve the coding efficiency of high-definition video,the high efficiency video coding(HEVC)standard is widely used.In the HEVC standardization process,due to the more efficient rate control performance,the ? domain rate control algorithm was adopted by HEVC.The rate control algorithm in the domain is designed to optimize the objective rate-distortion performance of the encoded video.The rate control algorithm of the ?domain is designed to optimize the objective rate-distortion performance of the encoded video.Without considering the impact of the human visual system(HVS)perception characteristics on the quality of the encoded reconstructed video,it results in low perceptual rate-distortion performance of the reconstructed video.In a video communication system,the reconstructed video is usually perceived by human eyes.Therefore,theoretically,considering the perceptual characteristics of HVS,a perceptual rate control algorithm that aims to optimize the perceptual rate-distortion performance of the reconstructed video can achieve better coding performance and provide better user perception experience.This paper considers the typical content characteristics of surveillance video analyzes the perceptual characteristics of human eyes,and proposes a regional-level rate control method to optimize the perceived quality of surveillance video based on the HEVC standard.This article mainly focuses on the following two aspects of study:1.In order to improve the perceptual rate-distortion performance for the rate control in HEVC,an intra-frame rate control algorithm to effectively improve the perceptual rate-distortion performance of surveillance video was proposed.First,the spatial and temporal complexity of videos were measured,then the subjective video observation experiment was designed combined with the spatial and temporal complexity.Second,based on the experimental results of subjective observation,combined with the relevant human vision perception characteristics,the spatiotemporal perceptual sensitivity factors of video content which can effectively measure the perception difference of human eyes for different regions of video were constructed.Finally,the spatiotemporal domain perceptual sensitivity factors were applied to the target bit allocation of the largest coding unit layer to realize the perceptual intra-frame rate control.Experimental results show that the proposed algorithm is significantly better than the rate control algorithm of the ? domain used by HEVC in terms of the bit estimation accuracy and perceptual rate-distortion performance.2.Considering the significant differences in the importance of images between frames,an inter-frame perception rate control algorithm suitable for surveillance video was further proposed.First,the spatial and temporal complexity of videos were measured,and combined with the spatial and temporal complexity to extract the video region of interest.Second,according to the region of interest and time layer information,the image layer target bit allocation weight was calculated,and the obtained weight was applied to the image layer target bit allocation.Finally,combined with the experimental results of subjective observation,the spatiotemporal domain perception sensitivity factors of video content were constructed and applied to the target bit allocation of the largest coding unit layer of the inter-frame image to realize the perceptual inter-frame rate control.The experimental results verify that compared with the ? domain rate control algorithm used by HEVC,the proposed perceptual inter-frame rate control algorithm can significantly improve the perceptual rate-distortion performance of encoded video while obtaining smaller bit allocation errors.At the same time,the algorithm complexity of the proposed algorithm is also lower.The rate control method proposed in this paper to optimize the perceived quality of surveillance video fully considers the perceptual characteristics of HVS,and directly or indirectly applies visual characteristics such as motion perception,selective attention mechanism,spatiotemporal domain resolution and masking effects to the rate control process.Optimized bit resource allocation significantly improves the overall perceptual quality of the encoded and reconstructed video.The study of this subject is also conducive to improving the judgment and recognition of targets in video surveillance. |
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