Axis Communications FD-R M12 - Manual (Page 42)

42 AXIS 209FD/FD-R/FD-R M12
Bit rate.
Monitor - A monitor is very similar to a standard television set, but
lacks the electronics to pick up regular television signals.
Motion JPEG - Motion JPEG is a simple compression/decompression
technique for networked video. Latency is low and image quality is
guaranteed, regardless of movement or complexity of the image.
Image quality is controlled by adjusting the compression level, which
in turn provides control over the file size, and thereby the bit rate.
High-quality individual images from the Motion JPEG stream are
easily extracted. See also JPEG.
Megapixel - See Pixel.
MPEG (Moving Picture Experts Group) - The Moving Picture
Experts Group develops standards for digital video and audio
compression. It operates under the auspices of the International
Organization for Standardization (ISO). The MPEG standards are an
evolving series, each designed for a different purpose.
MPEG-2 - MPEG-2 is the designation for a group of audio and video
coding standards, and is typically used to encode audio and video for
broadcast signals, including digital satellite and Cable TV. MPEG-2,
with some modifications, is also the coding format used by standard
commercial DVD movies.
MPEG-4 - MPEG-4 is a group of audio and video coding standards
and related technology. The primary uses for the MPEG-4 standard
are web (streaming media) and CD distribution, conversational
(videophone), and broadcast television.
Most of the features included in MPEG-4 are left to individual
developers to decide whether to implement them or not. This means
that there are probably no complete implementations of the entire
MPEG-4 set of standards. To deal with this, the standard includes the
concept of “profiles” and “levels”, allowing a specific set of
capabilities to be defined in a manner appropriate for a subset of
applications.
Multicast - Bandwidth-conserving technology that reduces
bandwidth usage by simultaneously delivering a single stream of
information to multiple network recipients.
Multiplexer - A multiplexer is a high-speed switch that provides
full-screen images from up to 16 analog cameras. Multiplexers can
playback everything that happened on any one camera with no
interference from the other cameras on the system.
Network connectivity - The physical (wired or wireless) and logical
(protocol) connection of a computer network or an individual device
to a network, such as the Internet or a LAN.
NTSC (National Television System Committee) - NTSC is the
television and video standard in the United States. NTSC delivers 525
lines at 60 half-frames/second.
OEM (Original Equipment Manufacturer) - This is a designation for
companies that manufacture equipment which is then marketed and
sold to other companies under their own names.
PAL (Phase Alternating Line) - PAL is the dominant television
standard in Europe. PAL delivers 625 lines at 50 half-frames/second.
PEM (Privacy Enhanced Mail) - An early standard for securing
electronic mail. The PEM-format is often used for representing an
HTTPS certificate or certificate request.
Ping - Ping is a basic network program used diagnostically to check
the status of a network host or device. Ping can be used to see if a
particular network address (IP address or host name) is occupied or
not, or if the host at that address is responding normally. Ping can be
run from e.g. the Windows Command prompt or the command line in
Unix.
Pixel - A pixel is one of the many tiny dots that make up a digital
image. The color and intensity of each pixel represents a tiny area of
the complete image.
PoE (Power over Ethernet) - Power over Ethernet provides power to
a network device via the same cable as used for the network
connection. This is very useful for IP-Surveillance and remote
monitoring applications in places where it may be too impractical or expensive to power the device from a power outlet.
PPP (Point-to-Point Protocol) - A protocol that uses a serial
interface for communication between two network devices. For
example, a PC connected by a phone line to a server.
PPTP (Point-to-Point Tunnelling Protocol) - A protocol (set of
communication rules) that allows corporations to extend their own
corporate network through private “tunnels” over the public Internet.
In this way a corporation can effectively use a WAN (Wide Area
Network) as a large single LAN (Local Area Network). This kind of
interconnection is known as a virtual private network (VPN).
Pre/post alarm images - The images from immediately before and
after an alarm. These images are stored in a buffer for later retrieval.
Progressive scan - Progressive scan, as opposed to interlaced video,
scans the entire picture, line by line every sixteenth of a second. In
other words, captured images are not split into separate fields as in
interlaced scanning.
Computer monitors do not need interlace to show the picture on the
screen, but instead show them progressively, on one line at a time in
perfect order, i.e. 1, 2, 3, 4, 5, 6, 7 etc., so there is virtually no
“flickering” effect. In a surveillance application, this can be critical
when viewing detail within a moving image, such as a person
running. A high-quality monitor is required to get the best from
progressive scan. See also Interlacing.
Protocol - A special set of rules governing how two entities will
communicate. Protocols are found at many levels of communication,
and there are hardware protocols and software protocols.
Proxy server - In an organization that uses the Internet, a proxy
server acts as an intermediary between a workstation user and the
Internet. This provides security, administrative control, and a caching
service. Any proxy server associated with a gateway server, or part of
a gateway server, effectively separates the organization’s network
from the outside network and the local firewall. It is the firewall
server that protects the network against outside intrusion.
A proxy server receives requests for Internet services (such as web
page requests) from many users. If the proxy server is also a cache
server, it looks in its local cache of previously downloaded web pages.
If it finds the page, it is returned to the user without forwarding the
request to the Internet. If the page is not in the cache, the proxy
server, acting as a client on behalf of the user, uses one of its own IP
addresses to request the page from another server over the Internet.
When the requested page is returned, the proxy server forwards it to
the user that originally requested it.
P-VOP - See VOP.
Resolution - Image resolution is a measure of how much detail a
digital image can hold: the greater the resolution, the greater the level
of detail. Resolution can be specified as the number of pixel-columns
(width) by the number of pixel-rows (height), e.g. 320x240.
Alternatively, the total number of pixels (usually in megapixels) in
the image can be used. In analog systems it is also common to use
other format designations, such as CIF, QCIF, 4CIF, etc.
RTCP (Real-Time Control Protocol) - RTCP provides support for
real-time conferencing of groups of any size within an intranet. This
support includes source identification and support for gateways like
audio and video bridges as well as multicast-to-unicast translators.
RTCP offers quality-of-service feedback from receivers to the
multicast group as well as support for the synchronization of
different media streams.
RTP (Real-Time Transport Protocol) - RTP is an Internet protocol for
the transport of real-time data, e.g. audio and video. It can be used
for media-on-demand as well as interactive services such as Internet
telephony.
RTSP (Real Time Streaming Protocol) - RTSP is a control protocol,
and a starting point for negotiating transports such as RTP, multicast
and Unicast, and for negotiating codecs.
RTSP can be considered a “remote control” for controlling the media
stream delivered by a media server. RTSP servers typically use RTP as
the protocol for the actual transport of audio/video data.