SDP summary

The Session Description Protocol (SDP) provides a representation of multimedia sessions like teleconferences, voice-over-IP calls or streaming videos. It is purely limited to the session description, hence it does not dictate requirements for certain transport protocols (there is support for essentially every transport protocol including Session Announcement Protocol (SAP), Real Time Streaming Protocol (RTSP), Hyptertext Transport Protocol (HTTP) or e-mail using the MIME extensions). SDP's purpose is to convey information about media streams rather than to negotiate session content or media encodings! SDP's mime-type is "application/sdp".

Our intention would be to create an SDP Web Service transport protocol.

An SDP session description includes the following:

  • Session name and purpose
  • Time(s) the session is active
  • The media comprising the session
  • Receiving parameters (addresses, ports, formats, asf.)
  • Bandwidth information
  • Contact information of responsible people

The following media and transport information is conveyed:

  • Type of media (video, audio, etc.)
  • Transport protocol (RTP/UDP/IP etc.)
  • Media format (H.261, MPEG, AVI etc.)

For multicast IP:

  • Multicast group address for media
  • Transport port for media

For unicast IP:

  • Remote address for media
  • Remote transport port for media

The following timing information is conveyed:

  • List of start and stop times bounding the session
  • For each bound, repeat times (e.g. "every Tuesday at 10am for one hour")

Structure:

The native SDP content is entirely textual using ISO 10646 character set in UTF-8 encoding. An SDP file consists of a number of lines of key-value-pairs: <type>=<value>. Each type and value consists of case-sensitive content, values may be separated into more values by using whitespaces. You will find a list of available keys and value patterns within the RFC document. It is also permitted to add custom key-value-pairs.

A typical SDP file:

Take a look at the attachment(s).

Attachments