| Following the popularization of Internet application, multimedia transport and publication on-line are areas of intense current interest, which promotes more and more people devoting themselves into them. There has been some multimedia transport and publication technologies based on Internet. However, they can't receive and transmit media streams in real-time. To send or receive a live media broadcast or conduct a video conference over the Internet or Intranet, we need to be able to meet the expectations of real-time applications. Then, streaming media is used to refer to both this technique of delivering media content over the network in real-time and playing the real-time media content that's delivered.Java Media Framework (shortended form JMF) provides a unified architecture and messaging protocol for managing the acquisition, processing, and delivery of time-based media data. With JMF, you can easily create applets and applications that present, capture, manipulate, and store time-based media. JMF is designed to support most standard media content types, such as AIFF, AU, AVI, GSM, MIDI, MPEG, QuickTime, RMF, and WAV. At the same time, it is designed to support the RTP and RTCP.The paper discuss the technologies being used to design and implement the Java application and Java applet that present, manipulate, and play Streaming Media. The groundwork, technological difficult point and innovation that this paper does are as follows:(1) Investigating new technology of multimedia processing. JMF completely inherits Java cross-platform. Inhence, the JMF programs have the speciality of "write once, run anywhere". JMF process all kinds of media files based on Java Media API, and apply it to actual development of the Streaming Media transmitting and playing system. Have solved several important problems in this system through using some key technologies that are RTP API, RTP session, port control, JMF event model, buffer and so on.(2) Study the formative mechanism of Streaming Media. The first of all, the multimedia files transmit on the Internet by datagrams capsulated. Therefore, encode these multimedia data according to some formats such as H.263, H.261, etc. In the same way, the reverse processes must be carried out for the playing of those multimedia data when get to the receiver, which are decoding and decompression. Commonly, only receive the whole media file can it be played. However, Streaming Media can be presented while downloading, that is to say, it doesn't need to store to the hard disk. Moreover, Streaming Media save a lot of time and space. It make use of buffer. It is well known that most media Players cannot be started instantly. Before the Player can start, certain hardware and software conditions must be met. For example, if the media data resides on a network device, the Player might have to establish a network connection before it can download the data. Or, if the Player has never been started, it might be necessary to allocate buffers in memory to store the media data packets (many data packets for stream are become media stream). so don't need to save data to a disk file. Because the size of buffer is limited, delete some media data being played completely while downloading. This becomes streaming media.(3) Do research on the multimedia files to carry through RTP transmissions, the realization about the unity of the application programming interface and independence in the platform based on the Java technique. To the control center of the JMF RTP API application, realize through... |
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