Axis 243Q Blade User Manual

Also see for AXIS 243Q Blade: Specifications Specifications User manual Installation guide Datasheet

Contents

Axis 243Q Blade User Manual Manual pdf 13 page image

13AXIS 243Q Blade - Video 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 e.g. network congestion. This is suitable for live video, as there isno point in re-transmitting old information that will not be displayed anyway.• 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 networkrouters.AXIS Media Control (AMC)The recommended method of accessing live video (MPEG-4 and/or Motion JPEG) from theAXIS 243Q Blade is to use the AXIS Media Control (AMC) in Microsoft Internet Explorer inWindows. This ActiveX component is automatically installed on first use, after which itcan be configured by opening the AMC Control Panel applet from the Windows ControlPanel. 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.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.