Axis 241QA 0230-004 Manual De Usuario
Los códigos de productos
0230-004
15
AXIS 241Q/S/QA/SA - Video and Audio Streams
Notes:
•MPEG-4 is licensed technology. The Video Server includes one license for the decoder required
for viewing in AMC. Installing additional unlicensed copies of this decoder is prohibited. To pur-
chase more decoder licenses, contact your Axis reseller.
chase more decoder licenses, contact your Axis reseller.
•All clients viewing the MPEG-4 stream must use the same image settings.
MPEG-4 protocols and communication methods
To deliver live streaming video over IP networks, various combinations of transport
protocols and broadcast methods are employed.
• RTP (Real-Time Transport Protocol) is a protocol that allows programs to manage the
real-time transmission of multimedia data, via unicast or multicast.
• RTSP (Real-Time Streaming Protocol) serves as a control protocol, to negotiate which
transport protocol to use for the stream. RTSP is thus used by a viewing client to start a
unicast session, see below.
• UDP (User Datagram Protocol) is a communications protocol that offers limited service
for 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 not
required to deliver all data and may drop network packets when there is e.g. network
congestion. This is suitable for live video, as there is no point in re-transmitting old
information 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 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 by simul-
taneously delivering a single stream of information to multiple network recipients. This
technology is used primarily on delimited networks (intranets), as each user needs an
uninterrupted data flow and should not rely on network routers.
The AXIS Media Control
The recommended method of accessing live video (MPEG-4 and/or Motion JPEG) and
audio from the Video Server is to use the AXIS Media Control (AMC) in Microsoft Internet
Explorer in Windows. This ActiveX component is automatically installed on first use, after
which it can be configured by opening the AMC Control Panel applet from the Windows
Control Panel. Alternatively, right-click the video image in Internet Explorer.
How to stream MPEG-4
Deciding on the combination of protocols and methods to use depends on your viewing
requirements, and on the properties of your network. Setting the preferred method(s) is
done in the control applet for AMC, which is found in the Windows Control Panel. When
this has been set, AMC will test all the selected methods in the specified order, until the
first functioning one is found.