DVR Compression

There are several different types of compression formats, and its not easy for anyone, including installers, to decide which one is more suitable for there requirements. So for now we will try to educate you on what compression actually is, and then let you know a little about the different types of compression’s used by the manufacturers of the Digital Video Recorders we offer.

So what is compression?

If you consider a digital camera with a Gigabyte of storage capacity can only hold a few hundred images (photos), CCTV systems may need to store up to 25 images every second for every camera. Unless we decrease the size of these image files the amount of storage capacity required for CCTV systems would be huge, and unpractical.
Compression is basically the process of reducing the file size of images to reduce storage space required
Compression Concepts

There are several compression formats on the market, using different methods to try to reduce file size while trying to keep as much image quality as possible. These compression formats revolve mainly around the two concepts:

Concept Name Figure Description
Spatial Compression  Figure 1. Spatial Compression  Used on a single image as  a completely independent  entity with no relation to  other frames, and  removes data not useful  for describing the image.
Temporal Compression Figure 1. Spatial Compression  Focuses on storing the  changes between  subsequent images  (frames) rather than the  entire frame in isolation.  If very little changes  between subsequent  frames then very little  storage space is consumed.

 Compression Formats

The main compression’s used by our manufacturers are MPEG-4, JPEG2000 & H.264. Below is a small guide to each one:

Compression Information Conclusion
H.264  Relatively new compression  within the security industry but is  becoming very ‘fashionable’.  Compresses the files more than  any format, allowing for large  amounts of storage  proportionally  to other  compressions, also due to  file  size less bandwidth is used for  remote viewing.  Great  compression  where large  recording  times are one  of the most  important  factors of  choosing your  Digital Video  Recorder.
JPEG2000  Largest file size of all  compression’s, so uses more  storage space than all others. But  it is this large file size that allows  it to produce the best quality  images.  Best  compression  when image
MPEG-4  This compression is an ‘all  rounder’. Although it doesn’t  have the image quality of the  JPEG2000 or the decreased file  size of H.264 it produces good  quality images at a more than  acceptable file size. Explaining  why it has been in the market for  so long and is still a popular  choice amongst manufacturers.  Good all  rounder.