GE Security SymSafe, User Manual

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Chapter 4
Programming the SymSafe
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Video Streaming is the process that the SymDec/SymSafe family, including SymNet and the Symveo IP
camera use to listen on a specific UDP/TCP port for control messages and respond to them. The
communication over this protocol can be between a PC application, such as SymNav software and any of the
above products. The UDP/TCP port is configurable. The default port setting is 8092. IP Multicast is also
supported.
IP Multicast
IP multicast is a bandwidth-conserving technology that reduces traffic by simultaneously delivering a single
stream of information to thousands of recipients. IP Multicast delivers source traffic to multiple receivers
without adding any additional burden on the source or the receivers while using the least network bandwidth of
any competing technology. High-bandwidth applications, such as MPEG video, may require a large portion of
the available network bandwidth for a single stream.
Note: Configured incorrectly IP multicast can become a serious drain on your networks resources! If you are at all uncertain
on how to setup IP multicast, please contact your network administrator or IS professional.
The Internet Assigned Numbers Authority (IANA) controls the assignment of IP multicast addresses. It has
assigned the Class D address space to be used for IP multicast. This means that all IP multicast group addresses
will fall in the range of 224.0.0.0 to 239.255.255.255. This address range is only used for the group address or
destination address of IP multicast traffic. The source address for multicast video is always the source or
senders IP address.
UDP Sender and UDP Receiver Overview
UDP (User Datagram Protocol), is a connectionless protocol that, like TCP, runs on top of IP networks. Unlike
TCP/IP, UDP/IP provides very few error recovery services, offering instead a direct way to send and receive
datagrams over an IP network. It's used primarily for broadcasting messages over a network. A UDP sender
sends out digital video over an IP network. A UDP sender can be the SymDec 4, SymSafe, Symveo IP Camera,
or SymNet (Encoder). A UDP receiver is typically a SymSafe, SymNav software, or a SymDec 4, which can
display and record the streamed video. The SymNet (Decoder) can also be setup as a receiver, but it can only
display the streamed video since it does not have recording capability.
To prevent a waste of network resources, the UDP sender does not send out streaming video until a receiver
informs the sender that it is interested in receiving the stream. The UDP receiver sends out a
START message
every 30 seconds to the IP address in its streaming settings menu. The streaming settings page is located on the
receiving device's web page.
When a sender receives a START message, it will start streaming out to the receiver's that are requesting it.
When the sender does not receive any START message for one minute, it will stop sending to that device.
To speed up the initialization process after bootup and configuration changes, The UDP sender sends out a
READY_TO_SEND message to the multicast IP address. When the receiver gets this message, it will send out
the START message immediately if it is configured to receive from that sender (It does not wait for 30 seconds).
Note: The above information also applies if your Sender and Receiver are configured to use TCP instead of UDP.
SymNav software
SymNav software is the next generation of software that supports MPEG-4 based video compression. The
SymDec 4, SymSafe, SymNet, and SymVeo IP Camera all use MPEG-4 compression.