2.2.7.1 Announce

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The purpose of the Announce request is to send information to the client on a new entry in a server-side playlist that the server will start to stream. The Announce request describes the playlist entry by using SDP syntax (section 2.2.5), providing the ASF file header as well as a URL for each stream, and information on the RTP payload format for each stream.

The Announce request is defined as the ANNOUNCE request method, sent by the server to the client, as specified in [RFC2326] section 10.3, with the following additional constraints:

The X-Receding-PlaylistChange (section 2.2.6.26) is allowed to be included in the request.

The Announce request is allowed to include the Cache-Control (section 2.2.6.2) header, because different cache control directives can apply to each entry in a server-side playlist.

The following example shows an Announce request with message body omitted.

 ANNOUNCE rtsp://myserver.com/ServerSidePlaylist.wsx RTSP/1.0
 Content-Type: application/sdp
 Vary: Accept
 Session: 13856065358275910855
 X-Playlist-Gen-Id: 5353
 X-Broadcast-Id: 73
 X-RTP-Info: url=rtsp://myserver.com/ServerSidePlaylist.wsx 
 /audio;transport=RTP/AVP/UDP;unicast;server_port=5004;
 client_port=1790;ssrc=90cbcaac;mode=PLAY;
 blocksize=5994;thinlevel=0;seq=26968;rtptime=0, 
 url=rtsp://myserver.com/ServerSidePlaylist.wsx/rtx;
 transport=RTP/AVP/UDP;
 unicast;server_port=5004-5005;client_port=1788-1789;
 ssrc=e740fe80;mode=PLAY;thinlevel=0
 Content-Length: 61337
 Date: Tue, 10 Sep 2002 23:09:36 GMT
 CSeq: 2
 User-Agent: WMServer/9.0.0.3191