Metafiles and buffering

While streaming audio or video file it often occurs that the browser downloads the entire file before calling an associated helper or plug-in to carry out the playback. To avoid this happening web page link not to the original file but to a metafile which just specifies the type and the name/URL of the actual data. Once the browser has loaded the metafile, it starts the correct helper and passes it the reference to the data file. The helper then opens buffers and plays the multimedia content while the web browser continues to display the original web page.

According to Levy metafiles ‘provide primitives that can be used to identify the components (URLs) in a media presentation and define their temporal and spatial attributes’ (Levy, 2001). One of the examples of such a file is SMIL (Synchronized Multimedia Integration Language).

Fig.3 Use of Metafile in Simplec Streaming Architecture

Another technology that make the streaming playback smooth is buffering.

The ideal streaming require the download rate to be greater than the playback rate – and the playback rate must be constant. As the data is being sent in small packets they is always a jitter problem to consider.  Buffer levels the difference. It collects a bunch of packets ahead, begins to play the file and continues to collect packets in reserve.
To reassume a buffer is a temporary storage location for data while the data is being transferred.