Axis 210A User Manual

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

Contents

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 manage thereal-time transmission of multimedia data, via unicast or multicast.• RTSP (Real Time Streaming Protocol) serves as a control protocol, to negotiate whichtransport protocol to use for the stream. RTSP is thus used by a viewing client to start aunicast session, see below.• UDP (User Datagram Protocol) is a communications protocol that offers limited servicefor exchanging data in a network that uses the Internet Protocol (IP). UDP is an alterna-tive to the Transmission Control Protocol (TCP). The advantage of UDP is that it is notrequired to deliver all data and may drop network packets when there is e.g. networkcongestion. This is suitable for live video, as there is no point in re-transmitting oldinformation that will not be displayed anyway.• Unicasting is communication between a single sender and a single receiver over a net-work. This means that the video stream goes independently to each user, and each usergets their own stream. A benefit of unicasting is that if one stream fails, it only affectsone user.• Multicast is bandwidth-conserving technology that reduces bandwidth usage by simul-taneously delivering a single stream of information to multiple network recipients. Thistechnology is used primarily on delimited networks (intranets), as each user needs anuninterrupted 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 e.g. the Internet.