VBrick Systems 7000 manual SDP and Announcements

Program Configuration

transmitting (in the case of multicast) and transmits if the client is reachable and listening (in the case of unicast). The streams are transmitted across the network via the RTP protocol encapsulated in UDP. You can configure up to 25 transmitters per program. Each transmitter can be configured for video and/or audio and the video and audio have separately-configurable destination ports. An "announce" can also be enabled for each transmitter.

Note • In a unicast environment, individual copies of the stream are sent from the source to each configured destination. In multicast, the stream is sent from the source only once and a network router will transmit the stream to multiple destinations.

•To avoid unnecessary network traffic, the transmitter will not send if the network socket fails to connect (has ICMP errors). In addition, Unicast destinations have a configurable Unicast ping option. See the Unicast Ping parameter on Program Configuration > Programs page.

SDP and Announcements

Decoders require knowledge of the stream from an .sdp file before it can be decoded. Each SDP description contains critical stream information such as profile, bit rate, addressing, transmission methods, and content. The decoder (for example StreamPlayer or QuickTime) will examine this file for all necessary configuration information relating to the stream. Upon power-up and service interruption, the decoder will re-establish stream decoding by relating back to information contained in the SDP file. SDP information may be requested via an RTSP request made from the client to the server whereby the server responds with the same information as contained in an SDP file. The SDP file may also be retrieved via an HTTP server residing either on the VBrick or on an external HTTP server. The URL address for the SDP file is based on the program and transmitter number, for example: http:// AAA.BBB.CCC.DDD/vbStreamXdY.sdp where: X is the program number, Y is the transmitter number and AAA.BBB.CCC.DDD is appliance IP address.

For multicast applications, where the VBrick is operating in Transmitter Mode, the SDP information is periodically broadcast to a pre-defined address via multicast announcements. For unicast announcements, a server can be configured to embed an RTSP URL within an announce message so a remote decoder can easily gain access to SDP information and subsequently initiate a Unicast RTP session. In some cases an H.264 stream may be sent to a third-party reflecting server which is not capable of emitting its own SDP announcements. Transmitters and servers can be configured to provide announcements advertising the URL of the reflected stream and/or required SDP information.

VBrick H.264 Appliance Admin Guide 49