Axis 243SA User Manual

Also see for 243SA: Specifications Installation guide User manual

Contents

Axis 243SA User Manual Manual pdf 15 page image

15Video and audio streamsMPEG-4 protocols and communication methodsTo deliver live streaming video over IP networks, various combinations of transportprotocols and broadcast methods are employed.• RTP (Real-Time 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, for example. This is suitable for live video, asthere is no point in re-transmitting old information that will not be displayedanyway.• Unicasting is communication between a single sender and a single receiver over anetwork. This means that the video stream goes independently to each user, andeach user gets their own stream. A benefit of unicasting is 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), aseach user needs an uninterrupted data flow and should not rely on network routers.AXIS Media Control (AMC)The recommended method of accessing live video (MPEG-4 and/or Motion JPEG) andaudio from the Axis video server is to use the AXIS Media Control (AMC) in MicrosoftInternet Explorer in Windows. This ActiveX component is automatically installed on firstuse, after which it can be configured by opening the AMC Control Panel applet from theWindows Control Panel. Alternatively, right-click the video image in Internet Explorer.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.