Axis 210A User Manual

Also see for Axis 210: User manual Specifications Product guide Installation guide Installation guide

Axis 210A User Manual Manual pdf 15 page image

15AXIS 210A/211A - Video StreamsMPEG-4 protocols and communication methodsTo deliver live streaming video over IP networks, various combinations of transportprotocols and broadcast methods are employed.• RTP (Realtime Transport Protocol) is a protocol that allows programs to managethe real-time transmission of multimedia data, via unicast or multicast.• RTSP (Real Time Streaming Protocol) serves as a control protocol, to negotiatewhich transport protocol to use for the stream. RTSP is thus used by a viewingclient to start a unicast session, see below.• UDP (User Datagram Protocol) is a communications protocol that offers limitedservice for exchanging data in a network that uses the Internet Protocol (IP). UDPis an alternative to the Transmission Control Protocol (TCP). The advantage ofUDP is that it is not required to deliver all data and may drop network packetswhen there is network congestion. This is suitable for live video, as there is nopoint in re-transmitting old information that will not be displayed anyway.• Unicasting is communication between a single sender and a single receiver over anetwork. The video stream goes independently to each user and each user getstheir own stream. With unicasting that if one stream fails, it only affects one user.• Multicast is bandwidth - conserving technology that reduces bandwidth usage bysimultaneously delivering a single stream of information to multiple networkrecipients. This technology is used primarily on delimited networks (intranets), asusers need uninterrupted data flow and should not rely on network routers.How to stream MPEG-4Deciding on the combination of protocols and methods to use depends on your viewingrequirements, and on the properties of your network. Setting the preferred method(s) isdone in the control applet for AMC, which is found in the Windows Control Panel. Whenthis has been set, AMC will test all the selected methods in the specified order, until thefirst functioning one is found.RTP+RTSPThis method (actually RTP over UDP and RTSP over TCP) should be your first considerationfor live video, especially when it is important to always have an up-to-date video stream,even if some images do get dropped. This can be configured as multicast or unicast.Multicasting provides the most efficient usage of bandwidth, especially when there arelarge numbers of clients viewing simultaneously. Note however, that a multicast broadcastcannot pass a network router unless the router is configured to allow this. It is thus notpossible to multicast over the Internet.Unicasting should be used for video-on-demand broadcasting, so that there is no videotraffic on the network until a client connects and requests the stream. However, as moreunicast clients connect, the traffic on the network will increase and may cause congestion.Although there is a maximum of 20 unicast viewers, note that all multicast users combined