Study Of Selective Retransmission Technology Based On The Importance Of Video Content

With the rapid development of wireless communications and IP (Internet Protocol)network, meanwhile the great improvement of video compression coding technology,video communication has become one of the main communication services. Inparticular, H.264 video coding standard with excellent compression performance andnetwork adaptability is extensively used in real-time video communications, Internetstreaming and other areas.However, the delay and packet loss of IP network, and error sensitivity of theefficient video compression coding will affect the transmission performance of videostreaming, resulting in poor video reconstructed quality, even destructed. So it isnecessary to ensure the video received quality by error control methods. Selectiveretransmission technology can successfully resend lost packets with small bandwidthand processing costs, becoming a research hotspot recently.The selective retransmission method in the current video applications and itsshortcomings are described firstly in this paper. Then, a no-reference video frameimportance evaluation method based on motion vectors is proposed over error-prone IPnetwork. In the evaluation method, according to variation correlation between themotion vector and error concealment distortion of video frame, we use motion vectorsto evaluate the importance of video frame. And next, a strategy of RTP (Real-timeTransport Protocol) encapsulation based on the importance value of video frames ispresented in this paper. The strategy arranges video frames in descending order of theimportance value, and gives an appropriate RTP encapsulation payload format.Finally, a video communication system with selective retransmission capability isintroduced based on the importance of video content in this paper. Experimental resultsshow that our method can obtain the significant improvement of both the objective andsubjective video quality compared with the randomly selective retransmission method,and can be used for the actual video communication products.