Difference between revisions of "SAP"

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SAP stands for Session Announcement Protocol. It's defined in [http://www.ietf.org/rfc/rfc2974.txt|RFC2974] (cache).
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{{Protocol|SAP}}
It's a distributed directory of announcements of streams and uses [[multicast]] to effeciently distribute these announces on the Local Area Network or on the [[MBONE]]. It uses [[SDP]]'s to describe streams so that you can open the stream via RTSP[[?]].
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{{wikipedia|Session Announcement Protocol}}
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'''SAP''' stands for '''Session Announcement Protocol'''.
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It is defined in [https://tools.ietf.org/html/rfc2974 RFC 2974].<br />
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It uses [[multicast]] to announce streams efficiently on a Local Area Network or on the [[MBONE]]:
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any computer on the network can receive announces from all others without any manual configuration.
  
This technique will allow you to have a lot of server produce streams (often multicasted) and announce themselves on the network. The clients on the network can then listen for these announces. VLC can do this with the sap interface. You then get a listing of all these streams and can simply 'tune' into the stream of your choice.
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SAP conveys [[SDP]]'s to describe streams parameters. This can include an [[RTSP]] control URL to use for setting up the stream, or a multicast group address to subscribe to. The SDP also includes port numbers and audio/video codecs parameters, and a stream name, etc.
  
It can also work for Internet telephony (SIP) for instance.
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This technique allows a lot of server to emit streams (often multicasted) and announce them on the network.
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Clients on the network can then listen for these announces.<br />
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VLC can do this with the "SAP" service discovery plugin.<br />
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You then get a listing of all these streams and can simply ''tune'' into the stream of your choice.
  
Example of what is announced via SAP on the MBONE:
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Because SAP uses [[multicast]] (as do [[wikipedia:UPnP|UPnP]] and Apple [[wikipedia:Bonjour (software)|Bonjour]]), it can normally only operate on a Local area network.<br />
http://www.uninett.no/multimedia/streamingguide/alle.html
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Unless your computer is connected to the [[MBONE]], you cannot use SAP to advertise your streams onto the Internet, nor can you receive streams from other places.
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== See also ==
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* [[MiniSAPServer]]
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* [http://www.uninett.no/multimedia/streamingguide/alle.html Example of what is announced via SAP on the MBONE]{{dead link}}
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[[Category:Protocols]]

Latest revision as of 07:06, 28 May 2019

SAP
VLC uses this protocol (or access module) to read data from a device or network.
This protocol is handled by the sap module.

SAP stands for Session Announcement Protocol. It is defined in RFC 2974.
It uses multicast to announce streams efficiently on a Local Area Network or on the MBONE: any computer on the network can receive announces from all others without any manual configuration.

SAP conveys SDP's to describe streams parameters. This can include an RTSP control URL to use for setting up the stream, or a multicast group address to subscribe to. The SDP also includes port numbers and audio/video codecs parameters, and a stream name, etc.

This technique allows a lot of server to emit streams (often multicasted) and announce them on the network. Clients on the network can then listen for these announces.
VLC can do this with the "SAP" service discovery plugin.
You then get a listing of all these streams and can simply tune into the stream of your choice.

Because SAP uses multicast (as do UPnP and Apple Bonjour), it can normally only operate on a Local area network.
Unless your computer is connected to the MBONE, you cannot use SAP to advertise your streams onto the Internet, nor can you receive streams from other places.

See also