Delay Optimization And Design Implementation Of Screen Live Broadcast System Based On Interactive Classroom

The projectors are usually used to share the screen in traditional multimedia teaching.However,there will be problems such as insufficient projection range,visual blind area,lake of intution and inability to interact when teaching resources are shared synchronously by multiple classrooms and multiple devices,especially in large classrooms.In response to these problems,"live broadcast + interaction",which is a new form of "Internet +education" teaching,came into being.Some schools have tried to introduce open and free Internet live broadcast platforms to solve the above problems,but some bad information is imported into the classroom through the open Internet in various ways,causing interference to the normal teaching order of schools.However,in the process of live broadcasting,there are some problems such as high delay of live broadcasting and poor fluency,which greatly reduce the teaching effect to some extent.Therefore,this topic firstly studies and solves the technical problems such as high delay and poor fluency in the process of live broadcasting under the LAN environment,and makes targeted optimization.Finally,a screen live broadcast system based on interactive teaching is designed and implemented.The main research contents and results of this paper are as follows:(1)Live stream fluency optimization: The push stream terminal monitors the network status at regular intervals,and three network quality models are determined by the two indexes of the network uplink average bandwidth and average round-trip delay,so that the push stream terminal can adaptively adjust the size of the code stream according to the different network status and ensure the smoothness of the live stream in different network environments.(2)Live broadcast delay optimization: delay optimization is carried out from the perspectives of first frame delay and video coding delay.Firstly,to solve the problem of long loading time of first frame and poor user experience,the key frame caching algorithm is implemented to optimize the opening time of first frame and reduce the opening time of first frame to 2~4 seconds.Then,optimize the selection algorithm of x264 4x4 brightness block intra-frame prediction mode by reducing the number of candidate modes,and the encoding time can be reduced by up to about 22% at most under the premise that there is little loss of video quality.(3)The wireless screen live broadcast system based on interactive teaching is designed and implemented,it can deliver computer screen images to tablets or mobile phones in real time and realizes the screen share live broadcast of multiple classrooms within the LAN.Compared with the traditional delay detection method,a method based on OCR(optical character recognition)is proposed to measure the delay of live broadcast at different video resolutions more accurately,providing evaluation basis and detection means for the optimization effect of live broadcast delay.In conclusion,the low-delay screen live broadcast system realizes the perfect combination of large-screen sharing and multi-device synchronous interactive teaching.It can realize the real-time demonstration of courseware and real-time operation of software.It also gets rid of the limitation of physical space between classrooms and satisfies the needs of screen sharing and live broadcast within the school LAN,which has very important practical application value and practical significance.