is media that is consumed (read, heard,
viewed) while it is being delivered. Streaming is more a
property of the delivery system than the media itself. The
distinction is usually applied to media that are distributed
over computer networks;
most other delivery systems are either inherently streaming
(radio, television) or inherently non-streaming (books, video
cassettes, audio CDs). The word "stream" is also used as a
verb, meaning to deliver streaming media. The remainder of this
article discusses technology for streaming media over computer
networks.Protocol Issue:
Designing a network protocol to support streaming media
raises many issues.Datagram protocols, such as the User
Datagram Protocol (UDP), send the media stream as a series of
small packets. This is simple and efficient; however, packets
are liable to be lost or corrupted in transit. Depending on the
protocol and the extent of the loss, the client may be able to
recover the data with error correction techniques, may
interpolate over the missing data, or may suffer a dropout.
The Real Time Streaming Protocol (RTSP), Real-time Transport
Protocol (RTP) and the Real-time Transport Control Protocol (RTCP)
were specifically designed to stream media over networks. The
latter two are built on top of UDP
.
Reliable protocols, such as the
Transmission Control Protocol (TCP), guarantee correct
delivery of each bit in the media stream. However, they
accomplish this with a system of timeouts and retries, which
makes them more complex to implement. It also means that when
there is data loss on the network, the media stream stalls
while the protocol handlers detect the loss and retransmit the
missing data. Clients can minimize the effect of this by
buffering data for display.
most other delivery systems are either inherently streaming
(radio, television) or inherently non-streaming (books, video
cassettes, audio CDs). The word "stream" is also used as a
verb, meaning to deliver streaming media. The remainder of this
article discusses technology for streaming media over computer
networks.Protocol Issue: