Quadrox WebCCTV Installation Manual - Manual (Page 52)

WebCCTV Installation Manual 52
Version 4.4 Series
For uncompressed video, the bit rate is calculated as:
Resolution x frame rate x colour depth (amount of bits per pixel)
Example: 5 fps of full D1 PAL video:
Bit rate = 768 x 576 pixels/frame x 5 frames/second x 24 bits/pixel
= 53084160 bits/second
= 50,6 Mbps
To illustrate the amount of data that this figure represents, let’s see how much uncompressed
video we can record on a standard machine with a 250 GB hard disk.
Recording time = 250 Gigabyte x 8 bits/byte x 1024 Megabit/Gigabit / 50,6 Mbps
= 40474 seconds
= 11,2 hours
This number needs to be divided by the number of sources (cameras) that we want to record on
1 system. This is of course unacceptable for a modern video surveillance recorder, which is
why we need video compression.
When we stream live video, the video data has to be transported over the network. The
capacity of the network to transport data is called bandwidth. It is also expressed in kilobit per
second (kbps). For network streaming, the rate at which video is transported is more important
than the total amount.
When storing video on a hard disk or other storage device, the total storage time is limited by
the capacity of the disk. This capacity is determined by the total amount of data that a disk can
contain. This is expressed in megabyte or gigabyte.
Please note that for streaming we use kilobit while for storage we use megabyte.