Streaming Media

What exactly happens when you play multimedia in your browser?

The streaming experience has improved over the years as our Internet connections have gotten faster. Not everyone understands that streaming actually depends on technologies and protocols different from those used for viewing Web pages or for downloading files.

What Is Streaming?
Streaming refers to the technique of continuous and steady digital data (audio, video, or graphics) transfer as “packets” in real-time from a data server through the Internet to a user’s computer. Media files can played in a browser using an embedded plugin or in a media player. The smoothness of the media stream depends upon the speed of the connection. Multiple versions in terms of quality (high, medium, or low) can be made available for different connection speeds. For slow connections, glitches in frames and delayed or no audio will occur.

A key factor is the compression method used for the media files so they can be streamed seamlessly. Due to compression, some data quality is compromised through perceptual encoding, that is, the audio/video is stripped down in such a way that the changes cannot be easily perceived. Usually, perceptual encoding refers to lossy audio encoding in which psycho-acoustics is used to determine what audio signals to encode and what to snip out.

Large media files are encoded using codecs to smaller sizes. Thus you have MOV, RM, etc.

RealNetworks, QuickTime, Windows Media and Macromedia Flash are the most common streaming technologies. Windows Media and RealNetworks are the most popular, and broadcasters assume that the player plugin is installed on the viewer’s browser. QuickTime is installed on all Macs. Also, installation of Macromedia Flash is required in most cases.

Types of Streaming
Streaming technology thus encompasses media content, the streaming server, plugins, and encoding software. Streaming is of two types-progressive and real-time.  During progressive streaming, the media file can be viewed or listened to while the file is in being downloaded. In the case of data loss, re-transmission of lost packets is possible. Media files streamed using the progressive technique get saved on the viewer’s hard drive, which raises the problem of re-distribution. HTTP streaming is a type of progressive streaming where the media file begins to play before it is entirely downloaded. In the case of HTTP streaming, a request for data remains open even after the data is received by the client, so that the server can respond at any time.

In real-time streaming, media content gets downloaded temporarily to the user’s computer. Almost-live broadcast of content is possible. Content streamed real-time can adjust according to the user’s connection capacity; if the connection is too slow, the transmission of data would break.

Media streams can also be distinguished as “on demand” or “live.” The former are stored on servers for long periods of time, becoming available to be transmitted to the user upon request. Live streams are available only at a particular time-like the streaming of a live TV broadcast.

A streaming server software package, the Real Time Streaming Protocol (RTSP) to control the interaction, and a matching client is needed for real-time streaming.