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WPS-500-PTZ-IP Installation Manual
18- Technical Information Glossary
18.1- Constant vs. Variable Bit Rate
IP cameras record light from a scene coming through a lens focused onto a sensor, and the image is converted into a digital format by
a processor to be streamed out over a network for viewing or recording. The amount of information converted by the processor
increases as the image becomes more complex.
For example, a camera recording a hallway or room where there is little activity and consistent lighting will be converting much less
information to stream out than a camera that is recording a crowded store where there is constant movement and a lot of changes in
lighting throughout the image. The camera can be set to handle the conversion in one of two ways, at a constant bit rate or a variable
bit rate.
Constant bit rate means that no matter the amount of information coming from the image sensor, the same amount of bandwidth is
being used to transmit the video feed. This means that image quality from a camera set to "CBR" may vary depending on the
complexity of a scene. CBR is useful when you want to conserve the amount of bandwidth being transmitted. This could be due to
slow network or internet speeds, or for conserving recording space when you are recording a scene where the clearest image quality
isn't necessary.
Variable bit rate means that the amount of bandwidth being used to transmit video varies with how much information is being sent.
Recording an empty, well lit hallway will yield a very low bandwidth signal. A camera installed outside with moving trees or cars
constantly passing by would transmit a very high bandwidth screen. Variable bit rate will always send the best quality image it can,
with no regard to the bandwidth used. This is optimal for situations where the high quality is required but be sure the network can
handle the extra traffic.
18.2- RTSP (Real Time Streaming Protocol)
RTSP, or Real Time Streaming Protocol, is a network protocol designed to allow media devices to stream content over Ethernet to
devices on the same network or even to devices over the Internet. Instead of using a separate server or video recorder to control the
video feed to remote devices, using RTSP in our IP cameras allows the direct control of the stream from within the camera. This
technology enables Wirepath™ products to stream video to devices even if they can't support any of our remote viewing apps.
18.3- ONVIF (Open Network Video Interface)
ONVIF stands for Open Network Video Interface Forum. "ONVIF is an open industry forum for the development of a global standard
for the interface of IP-based physical security products. ONVIF is committed to the adoption of IP in the security market. The ONVIF
specification will ensure interoperability between products regardless of manufacturer. The cornerstones of ONVIF are:
o
Standardization of communication between IP-based physical security
o
Interoperability between IP-based physical security products regardless of manufacturer
o
Open to all companies and organizations
The ONVIF specification defines a common protocol for the exchange of information between network video devices including
automatic device discovery, video streaming and intelligence metadata." (Excerpt from ONVIF.org)
So, basically, ONVIF is an organization known as a forum where all of its members collaborate and discuss the protocols and
technologies that IP based surveillance hardware implement for operation and communication.
What does this mean for dealers and end users? Devices built to the standards of ONVIF have been designed with seamless
integration and communication in mind. ONVIF certified equipment is guaranteed to operate together regardless of the brand of
equipment. These makes it easier for installers to get new jobs done with no unexpected incompatibilities and install more equipment
as needs increase and change over time without having to match exactly what is already installed. End users have the benefit of
having uniform methods of using the equipment, and the comfort of knowing they are buying something that is expandable and well
known. Any dealer can come in and change a job as needed even if they don't know what is in place, as long as the equipment is
ONVIF compatible.
Pg. 54
© 2013 Wirepath™ Surveillance
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