Research On Panoramic Videos Adaptive Transmission Technology Based On Tile

Panoramic video,also known as 360° video,is a special and novel type of video.With the rapid development of virtual reality technology,panoramic video has gradually entered people's field of vision.Panorama video brings a new experience to people with its immersive features,and become a new carrier of video service in the future.Panoramic video features high resolution and high bit rate,which poses a huge challenge for the transmission of panoramic video.At present,tile-based panoramic video adaptive transmission has become a major trend in panoramic video transmission.By dividing the panoramic video into multiple tiles,only the tiles in the region of interest is transmitted at a time according to the change of the user's field of view,effectively solving the above problem.However,this transmission scheme brings some implementation difficulties in practical applications.Because of the limitation of hardware device resources,the client cannot decode multiple tile streams simultaneously in real time,which brings great challenge to the low delay transmission of panoramic video.Therefore,this thesis studies the adaptive transmission technology of panoramic videos based on tile,and proposes a panoramic video adaptive transmission solution based on bitstream merge.In order to reduce the hardware requirements of the system to the client,a panoramic video adaptive transmission system based on tile is designed and implemented in this thesis.Combined with the improvement of H.265/HEVC motion constrained tile sets technology,a bitstream merge scheme is proposed.The multiple tile streams in the view are merged into one stream by modifying some syntax elements of the bitstream,so that multiple tile streams can be decoded in real time using a single decoder.And users can get a good viewing experience under different clients and different network conditions.The experimental results show that the improved H.265/HEVC motion constrained tile sets technology proposed in this thesis has an acceptable impact on the coding performance,and the time consumed by the bitstream merge is also negligible.On the whole,the tile-based panoramic video adaptive transmission system solves the decoding problem caused by the limited hardware resources of the client by using the improved H.265/HEVC motion constrained tile sets technology and the bitstream merge technology.In the case where the user ROI prediction is inaccurate,due to the limited coding structure of the video compression bitstream,there is always a problem that the high-definition tiles switching of the FOV area is not timely when the user performs the view switching,which affects the experience of the panoramic video transmission system to some extent.In order to solve the above problems,a fast view switching scheme based on code stream combination and a fast view switching scheme based on reference frame replacement for different scenarios in combination with the characteristics of MPEG-DASH protocol are proposed in this thesis.The experimental results show that while ensuring very small extra bandwidth consumption and negligible quality degradation,the two fast view switching schemes can effectively shorten the latency of the user's view switching and realize realtime view switching,which greatly improves the user experience.