A Research On Low Delay Algorithm Of Wireless Screen Transmission In Multi-screen Interaction

Multi-screen interaction means to implement the screen sharing among different devices, such as the phone’s screen is sent to the TV to get a good sense of the picture. Wireless screen transmission technology, as the core of multi-screen interaction,will directly affect the real-time performance of the multi-screen interaction. The real-time performance of wireless screen transmission depends on two key factors, the time consuming of video encoding and wireless transmission.Based on the study of the existing wireless screen transmission technology, to improve the real-time performance of the multi-screen interaction and reduce latency need to be improved from the video coding and the wireless transmission. Firstly, an advanced H.264 encoding technology was applied to video encoding. At the same time it has the features of low bit rate, high definition, strong network adaptability. Thus, low bit rate can be obtained which the video quality were ensured, reducing the burden on wireless network transmission.Secondly,in order to reduce time-consuming video coding, two ways of encoding were provided, soft coding method based on ffmpeg+x264, and hard coding method based on hard-coded processor.Thirdly, in terms of flow control, a new flow control algorithm(NARTP) was proposed in this thesis,after shortcomings of the existing flow control algorithm(constant reduction and variable constant growth flow control algorithm) were analyzed. The algorithm aims to reduce the packet loss rate, improve the transmission rate and TCP friendly.The multi-screen interaction test platform is built to test and verify the above research, the experimental results show that:1)Hard coding has more advantages compared with soft-coded encoding such as the encoding speed, low occupancy rate of CPU and so on. Therefore, the hard coded based on processor is encouraged in this paper.2)The NARTP algorithm had two obvious advantages compared with the constant reduction and variable constant growth flow control algorithm. One is to reduce the size of the packet loss rate and the other is to improve the stream transmission in unit time.3)the multi-screen interaction platform had been tested by the picture and HD video and obtained good results.