Video streaming

Definition

• Streaming video is a a video/audio data transfer technique to allow steady and continuous processing by a client.

Architecture

Multimedia (or video) streaming is based on the following technology

• In order to play video immediately as it is downloaded from the Internet (as opposed to storing it in a file on the receiving computer first) special servers and clients are needed.

• Clients can be web browser plug-ins or special stand-alone applications.

• A compression method (also called Codec). In order to decompress a file in real time, a fast computer is needed.

Streaming bandwidth and storage

Storage size

According to Wikipedia, storage size is calculated from streaming bandwidth and length of the media with the following formula:

storage size (in mebibytes) = length (in seconds) · bit rate (in kbit/s) / 8388.608

Real world example:

One hour of video encoded at 300 kbit/s (this is a typical broadband video for 2005 and it's usually encoded in a 320×240 pixels window size) will be:

(3600 s * 300 kbit/s) / 8388.608 = 128.7 MiB of storage 

Note: A mebibyte is roughly a megabyte.

Bandwidth

Problems arrise when lots of people pull the a file. E.g. if the above stream is viewed by by 1000 people, one would need:

300 kbit/s * 1000 = 300'000 kbit/s = 300 Mbit/s of bandwidth

See also: Videoconferencing

Links

Bytes

• Mebibyte (Wikipedia)
• Binary prefix (Wikipedia) (Wikipedia)
• Binary vs. Decimal Measurements (pcguide.com)