After hour of research, speaking to experts and reading current code of conduct, I thought I would offer some guidance for drivers looking to purchasing a CCTV System.
Their is generally three types of systems you can purchase.
SD Card (camera type card)
Flash Card (larger Card less common)
Hard Drive (2.5inch Hard Drive the same as seen in Laptops)
To give you a guide of things to take into account and their terminologies.
H.264-MP4Compression of the data, there are two types in the main, Mp4 (older) and H.264 (newer). The newer H.264 will compress the data (picture and sound) by half again. Meaning you will get "about" double the recording time for the same size of storage.
Frames Per second (FPS)European standard TV signal is 25fps. (meaning 25fps will give the smoothest picture)
Reducing the FPS will give the film a flicker book appearance, to the point were it would be a series of time laps photographs.
CamerasThere is generally three types for Vehicles known as
380 TV Lines
420 TV Lines
520 TV Lines
Again these are different resolutions.
420 is capable of IDing
Lens angles These come in many forms but as a guide for a Vehicle 1/3 3.6mm lens is spot on.
Warning!
One has to be very careful when purchasing the "all in one" systems, as many are fitted with a "fish eye" lens. These are designed to ID the driver NOT the rear view passengers. The lens makes the back seat so small that in many conditions this would not be possible.
IR (night Vision) Night Vision Cameras come with different filming distances in their design, so make sure that the camera offers around 2-5 metres, any more and the picture will be a white glare. Any less and the rear passengers will be in darkness.
**Please note, proper colour cameras switch to Black and White when filming in low light levels**.
Resolutions Most modern CCTV systems allow you to select a resolution.
examples are
CIF 320x320 low resolution, not for IDING people
Half D1 or CIF2 720 X 260 which is capable of IDing people
Full D1 720 X 520 this is High Definition.
Reducing the resolution will result in extended recording times but could make IDing people more difficult.
Half D1/CF2 is a happy medium.
Rough guide to storage times.
A 2 Camera system (filming at average resolution and 25fps) with Audio on a 32 GB card (Max on many systems) will give you around 30hr recording time. Conversely a 250 GB HD will give 234 Hr
Date, Time , Car Registration StampAny system has to have, Time, date and Car registration stamped on the film.
In order to seek conviction this is a must!! The car registration is also a must for insurance purposes.
Storage TypesSD and Flash cards now have tens of thousands of write times, so reliability is no longer an issue. However storage size to price is extremely expensive compared to traditional Hard dives. (this will fall in the coming years)
Although SD and Flash Card memory sizes are increasing, existing systems will not read these. So upgrade path is very limited.
Hard Drive systems can normally take anything from 80GB to 2TB (most the max is 500GB)
Hard dive failing or overheating.All modern Vehicle DVR use 2.5 Hard Dives as opposed to the 3.5 Hard drives used in older and standard PC's. This is for two reasons.
2.5 HD are designed for laptops which means they have much higher temperature tolerances, secondly they are designed to withstand shocks.
If purchasing a Hard Drive unit make sure it has a "good" make of Hard drive. All main stream manufacturers offer anywhere from 3 to even 10 year warranties 24/7 use.
SSD, Solid State Drives These are the future and will eventually replace mechanical Hard Drives altogether(a good 5 to 10 years away). The GOOD NEWS is, any 2.5 Hard Drive system can be upgraded to a Solid State Hard Drive, as opposed to SD Card systems that can only read the Card size they have been designed for (usually 32Gb).
So an ideal system is....
2 x Camera, recording inside and outside front (for Insurance purposes)
1/3 2.6mm 420 TV Lens, Night vision IR 3/5 Metres Max
Date, time, reg number stamp.
Set to record 25Fps at medium resolution Half D1
Storage minimum 120GB which will give roughly 112Hr
Talking to CCTV suppliers and Insurance companies many incidents that require evidence to resolve don't come to light for several days after the event. I think 112Hr is a happy medium between cost and efficiency.
Hope this helps anyone walking the minefield of CCTV. Welcome anything I may of missed or question feel free to add/ask.
