Research On Adaptive Transmission Technology Of Panoramic Video

With the rapid development of the virtual reality technology and the increasing of network bandwidth,panoramic video has quickly become one of the important contents of the network video with its immersive experience.With the improvement of the video quality requirements of users,the user experience of the network panoramic video has become increaingly important.At present,the transmission mode of panoramic video hasn't been unified,and different panoramic video transmission methods can provide users with different viewing experiences.This thesis studies the quality of user experience of the panoramic video DASH service,and analyzes the user experience quality of panoramic video under several typical transmission methods.An experience quality assessment model for tile-based panoramic video DASH service is also proposed.It is significantly important to improve the user experience and promote the development of panoramic video.At present,there are three common transmission schemes for DASH transmission of panoramic video: the full-view transmission scheme,the transmission scheme that only transmit the video content in the viewport,and the transmission scheme that preferentially transmit the high quality video in the viewport.This thesis researches about the quality of user experience under these three transmission schemes.In order to simulate the actual viewing experience,the panoramic video DASH transmission system is developed baesd on the head-mounted display device.The system can support smooth video playback for panoramic video which has 4K resolution and 30 fps frame rate.Subsequently,a subjective experiment was designed and implemented on the transmission system,then the user experience quality under the three transmission schemes was explored.The experimental results show that the transmission scheme with priority for viewport quality can provide users with a better viewing experience while saving transmission bandwidth,and the scheme has a better performance in terms of user experience than the other two transmission schemes.One solution that can be used for the panoramic transmission schemes which priority transmit the high quality viewport's video is tile-based streaming.To predict the user perceptual quality of tile-based DASH panoramic video in real time,an event-based perceptual quality assessment model is proposed.At first,according to the playing feature of the tile-based DASH panoramic video,the user's viewing processing is divided into two events,and one event is that the user's viewport has a part of low quality video and a part of high quality video,and the other event is that the user's viewport is full of high quality video.And then an event-based perceptual quality assessment framework is proposed.And then to analyze the characteristic of perceptual quality during each type of event,a subjective quality assessment experiment was designed to obtain the perceptual quality at a series of point in time.Based on the experimental results,a perceptual quality assessment model was proposed to predict the changed perceptual quality after each event.The experimental results show that there is a high consistency between the subject quality and the object quality which is predicted by the proposed model in this thesis.And this indicates that the proposed model can accurately predcit the user's real-time experience quality of tile-based DASH panoramic video.