Solution Of The Network Video Education Developed With DirectShow

Remote education is an important part of the network multimedia technique. It breaks through the limitation of the space-time and brings great convenience to the learners.The network video education plays an important role in the remote education. It realizes the communication of the video/audio on the network between the teachers and students. There are three ways to implement the network video education: hardware solution, software solution and hardware-software solution.Remote education has been widely used in our country, but there are still some problems in the realization of the network video education:1. The cost of the hardware solution of the network video education is too high for the users.2. The video/audio quality of the software solution can not satisfy the users. And the software solution doesn't support asynchronism education and multicast.3. The codecs used in the hardware solution and software solution follow the H.323 standard. The output media format is so simplex that it can not adapt well to the change of the users' requirement and network condition.Aiming at these problems, this paper designed a software solution of network video education which was developed with DirectShow. This software solution overcomes the shortcomings of the software solution before , it accomplishes the following work:1. Replacing the special and expensive equipments by the cheap ones, using software to capture, encode/decode, and record the video/audio data.2. Supporting MPEG-4 and MP3 codec, designing the network transmit method of these media data.3. Providing the compatibility for kinds of codecs, and the configuration of these codecs and video/audio's quality.4. Supporting synchronism education, asynchronism education and multicast. This paper is mainly about the three layers' design of the solution:1. UI layer. It provides the user interface, which allows the users configuring the devices and the codecs to meet their requirement.2. Graph manager layer. In this layer, to serve for the UI layer, this paper designed a series ofhigh level functions based on the DirectShow API.3. Filter layer. In the Filter layer, this paper designed a network transmit filter to implement the media data's transmission. The network transmit filter encapsulates the media data into the RTP packets, and uses special method to separate the MPEG-4 data. When receiving media data, it uses asynchronism receiving mode, multi-cache and multi-thread to improve the system performance. And because it is developed with COM, it has better expansibility.The purpose of this paper is: designing a software solution of network video education with the advanced DirectShow technique. The features of this solution are: low cost, better Video/Audio quality, compatibility for more codecs, kinds of configurations which allow users doing different tasks and adjustment for the change of network condition.