Abstract
With the growing popularity of personal digital assistant devices and smart phones, more and more consumers are becoming quite enthusiastic to appreciate videos via mobile devices. However, limited display size of the mobile devices has been imposing significant barriers for users to enjoy browsing high-resolution videos. In this paper, we present an attention-information-based spatial adaptation framework to address this problem. The whole framework includes two major parts: video content generation and video adaptation system. During video compression, the attention information in video sequences will be detected using an attention model and embedded into bitstreams with proposed supplement-enhanced information (SEI) structure. Furthermore, we also develop an innovative scheme to adaptively adjust quantization parameters in order to simultaneously improve the quality of overall encoding and the quality of transcoding the attention areas. When the high-resolution bitstream is transmitted to mobile users, a fast transcoding algorithm we developed earlier will be applied to generate a new bitstream for attention areas in frames. The new low-resolution bitstream containing mostly attention information, instead of the high-resolution one, will be sent to users for display on the mobile devices. Experimental results show that the proposed spatial adaptation scheme is able to improve both subjective and objective video qualities.
Highlights
Recent advances in wireless networks, especially with the emergence of 3G network, have enabled a new array of applications in image and video over wireless networks beyond traditional applications in voice and text
In order to meet the constraints of display size and bandwidth while optimizing the perceived video quality, we propose an attention-information-based spatial adaptation framework which is composed of two processes: the preprocessing of video content and the video adaptation stage
Even though the spatial adaptation based on region of interest (ROI) transcoding is able to provide high-quality ROI for display on the mobile devices, we will point out that there is a need to design a new scheme in order to overcome two inherent shortcomings associated with the ROI transcoding-based video adaptation
Summary
Recent advances in wireless networks, especially with the emergence of 3G network, have enabled a new array of applications in image and video over wireless networks beyond traditional applications in voice and text. The other critical constraint is the limited display size of mobile devices, which often hinders the users to fully enjoy the video scene. These methods improve the visual quality by increasing the number of bits allocated for ROI in frames They did not address the problem caused by the limited display size of mobile devices. In order to meet the constraints of display size and bandwidth while optimizing the perceived video quality, we propose an attention-information-based spatial adaptation framework which is composed of two processes: the preprocessing of video content and the video adaptation stage. Based on the detected attention information, we develop an approach to improve both coding performance of original video and transcoding performance and visual quality of video adaptation by adjusting bit allocation strategy for attention and nonattention areas within a video frame.
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