eLine Technology iVMS-2000 V2.0.2 - Manual (Page 113)

iVMS-2000 User Manual
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representation of horizontal and vertical pixels.
Image resolution refers to the size of digital image, also represented by horizontal and
vertical pixels.
If the image resolution is bigger than display resolution, then some images can’t be
displayed.
Pixel resolution refers to a ratio of pixel’s width and length. Different ratio will cause the
deformation of images.
Common Image resolution modes in digital surveillance are:
PAL: QCIF (174*144), CIF (352*288), 2CIF (704*288), DCIF (528*384), FULL D1
(704*576) , VGA (640*480) , SVGA (800*600) , UXGA (1600*1200) , HD720P (1280*720) .
NTSC: QCIF (174*120), CIF (352*240), 2CIF (704*240), DCIF (528*320), FULL D1
(704*480), VGA (640*480), SVGA (800*600), UXGA (1600*1200), HD720P (1280*720).
Common VGA resolution: 640*480, 800*600, 1024*768,1280*1024, etc.
Dynamically Adjust Encoding Parameters
The dynamically adjusted encoding parameters can take effect at once without pausing
or restarting network transmitting and recording.
In surveillance system, for static monitoring scene, video can be recorded in low bit rate
through reducing resolution, image quality, bit rate and frame rate, while changing of images
require higher resolution , bit rate and frame rate of video, etc to get high quality video
stream. Since the above parameters can be dynamically modified, continuous images can be
maintained without switching files frequently. And it does not only meet the requirement of
high-quality images at critical moments, but also save the disk space and network bandwidth.
File System Fragment
When a file is recorded and scattered in discontinuous clusters, the content in the
discontinuous clusters is called file system fragments. When contents of the files in the hard
disk were frequently deleted and re-written, the file system fragments will appear easily, and
thus increase the seeking delay and rotation delay of the hard disk, and then affect its
efficiency and life-span.
If the file is defined beforehand and pre-allocated to consecutive clusters, the generating
of file system fragments can be completely avoided.