| Thanks to the rise of computer and multi-media technology coupled with Internet, distance education has been injected new momentum. In the late two decades, the continual and rapid development of our society has rendered demands for human resource increasing urgent. Currently, 67 universities and colleges of higher learning have initiated pilot work of modern distance education within the country, with more than 30,000 stream media and web course wares developed totally and abundant teaching resource such as network teaching material, assignments, exercises and tutorship, etc. However, the separate and isolate construction of resource such as course wares has raised the problems of various quality, repeated construction and disability in sharing.As a state of the new network technology, stream media technology compresses and encodes the consecutive video and audio datum, then published to dedicated stream media servers, which enables users watch by downloading without need to tolerating the completeness of whole process. It serves to shorten the waiting time of replay and offer better QoS, therefore resolves the problem caused by limited network bandwidth.This thesis conducts an in-depth study on technologies of compilation concerning ASF formatted stream media course wares, combining CNGI distance education public communicating platform sponsored by National Development and Reform Commission and spec of ASF. Two parts are included in this thesis, firstly, introduction of stream media and its theory; secondly, discussion and summary of design and implementation during development of ASF formatted steam media course wares. The edit and process of ASF formatted stream media consists of two parts: the implementation of cut and conversion from none ASF formatted stream media files such as AVI, MPG to ASF formatted stream media files; implementation of cut and merge of ASF files. Cut and merge have something in common, for instance, acquirement of profile information, judgment on DRM protected or not, automatic encoding and decoding function averting Reader Object and Writer Object as well as modification of meta-data information. Above mentioned two functions have to be implemented separately due to their differences.Format and systematic characteristic of ASF file are explored as the basis for learning structure of ASF file. Next, technologies involved in the cut, conversion and edit of stream media are studied respectively. Design of the whole system and each functional modules are given in chapter 4. Visual C++ is used for programming implementation in the end.Relevant software package has passed the test by Chongqing Software Evaluation and Test Center in terms of installation, uninstallation, function, stability and integration of interfaces. It has met the requirement of spec for Software Product Grade Test with considerable application value. |
