DS2 Setup Guide

DS2

Image quality

Digital multiplex recorders store images in a compressed format, allowing images to be recorded

more efciently. The higher the compression, the smaller the le size, but the image quality will

suffer. The DVR offers a range of compression options and image storage formats to give the end

user the exibility to balance between image quality and storage capability.

Kilobytes and Gigabytes are units of storage, 1GB = 1000 Megabytes (MB) and 1MB = 1000

Kilobytes (KB), according to modern hard drive specications. (Now specied under SI units as

one kilobyte (1 kB) = 1000 bytes, whereas one kibibyte (1 KiB) = 1024 bytes to clear the confusion

caused by the term kilobyte simultaneously being used to refer to both 1,000 and 1,024 bytes)

With analogue recording, the image quality is dependent on the type of VCR being used; VHS or

S-VHS. The unit allows the image quality to be altered by adjusting the image size, for example, Low

quality is 14KB, Medium is 18KB, and High is 25KB.

Note:

As for all digital recording, image quality can vary for different scene types, Medium quality

may be 18KB in one scene, but it may be 30KB or more to get the same quality in a scene

with more detail.

Using a larger image size will ll the hard disk faster than a smaller image size, as more space is

required to store it. To achieve the same amount of recording time when a larger image size is used

requires the record rate (PPS) to be reduced.

Standard record rate

The record rate is the amount of pictures recorded to disk in a second, or pictures per second (PPS).

This is a system wide gure and is not effected by how many cameras are connected. The update

rate per camera can be worked out using the record rate:

Update rate = No. of cameras/Record rate

Hard disk capacity

Using a larger hard disk will allow image quality, recording rate, or recording time to be increased.

MultiMode Recording

MultiMode recording offers the ability to set different recording rates, resolutions and compression

across scheduled, normal and alarm modes, or to mix a standard setting for many cameras with

individual settings for particular cameras and time of day. By varying the quality (bitrate) of the

recorded image, users can increase recording capability of the unit.

MultiMode recording offers:

Ability to set different recording resolutions including 704x512, 704x256, 352x256 and 176x128.

Ability to set MPEG or JPEG compression recording.

Ability to set PPS recording rates.

Dynamically switchable resolution when switching from Normal to Event Recording.

Dynamically switchable compression between MPEG4/JPEG from Normal to Event Recording.

Calculating recording time

The unit calculates the recording time automatically when the record rate and image quality are

entered. Using the Camera Setup wizard available through the web interface, will allow you to get

the optimum settings for your requirements. These can still be edited later.

Alternatively, an interactive record calculator is available for download from our web site: