The traditional way to transmit audio, video and other multimedia information on the network is to download it completely before playing it. Downloading often takes several minutes or even hours. Using streaming media technology, streaming transmission can be realized, and sound, image or animation can be continuously transmitted from the server to the user's computer. Users don't have to wait until the entire file is downloaded, but can watch it after a startup delay of several seconds or more. When the audio and video are played on the user's machine, the rest of the file will continue to be downloaded from the server.
If file transfer is regarded as a process of receiving water, then the past transfer mode is like setting a rule for users that they must wait until a bucket of water is full before using it. This waiting time is naturally affected by the water flow and the size of the bucket. On the other hand, in streaming transmission, after turning on the tap and waiting for a short period of time, water will flow out continuously and be ready for use. Therefore, users can use water at any time regardless of the water flow or the size of the bucket. In this sense, the word streaming media is very vivid.
There are two kinds of streaming technology, one is sequential streaming, and the other is real-time streaming.
Sequential streaming is sequential downloading, and users can watch files while downloading. However, the user's viewing is not synchronized with the transmission on the server. Users can only see the information uploaded by the server after a period of delay, or always see the information transmitted by the server some time ago. In this process, users can only watch the downloaded part, and can't ask to jump to the part that has not been downloaded. Sequential stream is more suitable for high-quality short clips, because it can better ensure the final quality of program playback. Suitable for audio and video programs published on the website for users to order.
In real-time streaming, you can view audio and video information in real time. In the process of viewing, users can fast forward or backward to watch the content in front or behind, but in this transmission mode, if the network transmission conditions are not ideal, the effect of receiving signals is poor.
When using streaming media technology, audio and video files should adopt corresponding formats, and files with different formats need to be played by different player software, which is called "a key opens a lock". There are three main types of audio and video files using streaming media technology.
One is Microsoft's ASF (Advanced Stream Format). The suffixes of these files are. Asf and. Wmv, and the corresponding player is Microsoft's "media player". Users can combine graphics, sound and animation data into a file in ASF format, and can also convert videos and audio in other formats into ASF format. Moreover, users can also save the data of microphones, video recorders and other peripherals in ASF format through sound cards and video acquisition cards.
The second is RealMedia of RealNetworks, which includes three types of files: RealAudio, RealVideo and RealFlash, among which RealAudio is used to transmit audio data close to CD sound quality, and RealVideo is used to transmit uninterrupted video data. RealFlash is an animation format with high compression ratio jointly launched by RealNetworks and Macromedia. The suffix of this kind of file is. Rm, the player corresponding to the file is "RealPlayer".
The third is Apple's QuickTime. This file extension is usually. Mov, its corresponding player is "QuickTime"
In addition, MPEG, AVI, DVI and SWF are all file formats suitable for streaming media technology.
Because streaming media technology has broken through the limitation of network bandwidth on multimedia information transmission to a certain extent, it is widely used in many fields such as online live broadcast, online advertising, video on demand, distance education, telemedicine, video conference, enterprise training, e-commerce and so on.
For news media, streaming media has brought both opportunities and challenges.
Streaming media technology provides the possibility for traditional media to open up a broader space on the Internet. It is more convenient for radio and television media programs to access the Internet, and it is easier for listeners and viewers to order programs online. Online audio and video live broadcast will also be widely used.
Streaming media technology transforms the "push" communication of traditional media into the "pull" communication of audience. Instead of passively receiving radio and television programs, viewers receive the information they need at their own convenience. This will improve the status of the audience to a certain extent, make them master the initiative of news dissemination, and also make their needs have a more direct impact on the activities of the news media.
The wide application of streaming media technology will also blur the boundaries between radio, television and network. Network is not only the auxiliary and extension of radio and television, but also a strong competitor of radio and television. Using streaming media technology, the network will provide new styles of audio and video programs, and will also form new commercial ways, such as pay-per-view services. Giving full play to the advantages of traditional media, making use of the specialties of online media and maintaining good competition and cooperation between media are the future development paths of network and traditional media.