Examining IR Illuminator Bandwidth Savings and Raytec's Test ResultsBy John Honovich, Published Oct 09, 2010, 08:00pm EDT (Research)
In the past few years IR illuminator vendors have made strong marketing claims about dramatic bandwidth savings achieved by using IR (80-95% [link no longer available] reductions). In our IR testing, we found that wide outdoor scenes (common in surveillance) either received minimal or no benefits.
Raytec explained their test methodology. The tests demonstrating 95% bandwidth reduction were done indoors in a blackbox using an Arecont Vision megapixel cameras (VBR mode). Raytec also performed outdoor testing where bandwidth from an Arecont Vision camera was reduced from 7.3 Mb/s to 2.9 Mb/s when using IR (a reduction of slightly more than 50%).
Bosch / Extreme CCTV reported a similar methodology conducting indoor / blackbox testing that produced similar dramatic bandwidth reductions as Raytec.
As we showed in our tests and as the vendor's test demonstrate, the highest savings come from the least likely real-world scenarios - specifically, indoors, with the camera and IR illuminator pointed at a white surface a few feet away with narrow field of view.
Secondly, in our testing of Arecont Vision's 2105 and 3105 cameras, we found their low light bandwidth consumption to increase far more dramatically than other H.264 VBR cameras (e.g., Axis and Basler). Also, some cameras are CBR only (like the Sony HD camera we tested). By design, the bit rate of CBR cameras do not change (or change only slightly) due to lighting or image changes).
One element Raytec pointed out was that if the IR illuminator coverage area matched the entire FoV of the camera, that the bandwidth savings should increas even outdoors. Observers will notice in our test that the illuminator created a bright spot in the center with dark areas around the outside. We think expanding the IR illuminator coverage to match the FoV should reduce the bit rate. However, it remains to be tested and determined how well and what other issues one faces in achieving this.
As it remains, while the potential for very significant bandwidth savings exist, users should be cautious about the actual bandwidth savings they achieve and should factor in the camera type, streaming mode, illimuninator coverage and area surveilled when setting expectations for bit rate reduction.
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