The Application of Mirror-driven Screen Capture Technology in Digitized Voice Classrooms
Abstract Digitized Voice classrooms, distance learning and other network applications require real-time high speed to catch on the PC screen information. Traditional API methods, By calling the Windows system function to copy the interception of the screen information will consume lots of CPU resources, In this paper, mirror driver, only 5% -10% of the cost of CPU resources per second interception of 10-20 screen images, achieve real-time PC screen capture information purposes. Another feature of these new businesses is the server will be Video Streaming Media Player, receiver must have a coherent visual effect. In this way, using traditional API methods will have the following shortcomings: 1. Can not catch the streaming media video images. This is because video broadcast in the process of systems are often called DirectDraw to accelerate video broadcast Due to the special nature of DirectDraw, the API used directly to the province, Video capture will not screen information. In this paper, mirror-driven, the equipment will be able to capture layer of the screen information, Mirror Driver advantage is the direct use of hardware, user mode to make the enterprises and the "real-time", it is because the use BitBlt copy screen contents Its data transmission needs from memory to memory, after low-speed busiest bus, natural than from memory to memory to copy data much slower. 2. A serious waste of network resources, a 1024 * 768 pixel screen bitmap is about 4M, 20 per second is 80M. Such a large volume of data transport in some low bandwidth link, is very likely to lead to a serious bottleneck in communications. In this paper, using the JPEG image compression algorithm in the visual without compromising the quality of images will be captured under the bitmap efficient compression, and then compressed image transmission to the client, even if there are thousands of clients, will not cause the collapse of the network.
