1. Calculating Processing and Storage requirements for Megapixel CCTV
SPECIALISED SERVER TECHNOLOGY FOR HD SURVEILLANCE
Calculating Processing and Storage requirements for Megapixel CCTV

2. AGENDA
The basic formulas for calculating IP CCTV Bandwidth and Storage are as follows Bandwidth(Mbps) = FrameSize(Kb) * FPS * Cameras / 1024 Storage Space(TB) = (Bandwidth(Mbps) * Days Reqd * 24hr * 60min * 60sec * %Activity) / (8 x 1024 x 1024) We will be looking at each component and the variables involved in this calculation to enable you to do manual calculations if required as well as looking at the best use of some of the industry available calculators and potential shortfalls in their use.

3. FRAME SIZE The physical size in Kb of individual images
A combination of resolution and compression
Higher resolution = higher frame size
Higher compression = lower frame size
Whilst compression codecs are improving all of the time in general the greater the compression the worse the image quality

4. COMPRESSION Full frame compression (JPEG, MJPEG, JPEG2000)
There is nothing more data intensive than video…….. except multiple streams of HD Video!! As a result CCTV applies compression to allow the huge amount of images we require to be stored
Full frame compression (JPEG, MJPEG, JPEG2000)
Compression applied across full image but a full frame is captured very time
Frame size and Bitrate are constant and easy to calculate
Less compression artefacts in fast moving objects
Much higher storage overhead
Peak bitrate and Average Bitrate are the same
Manufacturers default settings are usually optimised for image quality / Bitrate trade off.

5. COMPRESSION Conditional compression (MPEG2, MPEG4, H264)
There is nothing more data intensive than video…….. except multiple stream of HD Video!! As a result CCTV applies compression to allow the huge amount of images we require to be stored
Conditional compression (MPEG2, MPEG4, H264)
Image stream is made up of Key frames (I frames) and partial frames (P frames) where only the movement in the image is updated relative to the Key frame.
Bit rate is variable and harder to calculate
Increased scene complexity and scene activity increase bit rate
Peak bitrate used for processing calculation and Average bitrate used for storage calculation
Generally much lower storage requirement
Manufacturers default settings are usually optimised for image quality / Bitrate trade off.

6. SCENE ACTIVITY
This is where experience can play a big part in calculating storage during a site survey
The amount of bandwidth taken up by an H264 compression will be defined by scene complexity and scene activity
A ‘complex’ background eg a brick wall will not compress as efficiently as a plain background eg a white wall
Ambient scene activity will still increase bitrate , think about trees, sea, clouds, etc
Image noise at low light still constitutes scene activity as far as the camera is concerned and is often a cause of bitrate peaking at night
PTZ movement constitutes very high scene activity as a moving camera is equivalent to a constantly moving image

7. MOTION DETECTION
This is where experience can play a big part in calculating storage during a site survey
Ambient and non relevant movement can be filtered out and trigger levels set to determine when recordings are captured
Very useful for reducing storage requirements where several cameras are in sterile environments for portions of the recording period
Allow engineering time to set up. Leaving motion settings on default rarely delivers the required results
A second site visit after the system has been running a while can usually offer significant improvements in storage efficiency.
Video analytics can further fine tune which events are to be captured and stored

8. BITRATE
For full frame rate recording this is easy to calculate , Bit rate per camera (Kbps) = Frame size (Kb) x Images per second
For H264 most camera manufacturers will give charts of Average bitrates at various compressions and scene activities
If you standardise on cameras do your own tests to be comfortable with bitrates in various scenes
Average Bitrate is used to determine storage requirements for a server / system
Peak bitrate is used to determine throughput requirements for a server / system
Many systems allow the Peak bitrate to be capped

9. BITS vs BYTES
Usually, we refer to file sizes and file transfer speeds in megabytes (MB).
Throughput and bandwidth are calculated in megabits per second instead (Mbps).
One byte is made up of 8 bits, which means that when doing your calculations you need to pay extra close attention to which unit you're using
Bits (the smaller of the two) is abbreviated to lower case "b" and bytes (the larger) is abbreviated to upper case "B“

10. ARCHIVE TIME
Quite simply, how long does the customer hope to retain video for? Once this is established this number remains a constant for the calculation and per camera follows the following formula Total recording (s) = Days x hours x minutes x seconds So for 31 days 24/7 recording Total recording (s) = 31 x 24 x 60 x 60 = 2,678,400 seconds

11. THE FORMULAS
If all cameras have the same resolution / frame rate / etc the formulas are as below
Peak Bandwidth (Mbps) = Peak Bitrate (Mbps) x number of cameras
Average Bandwidth (Mbps) = Average Bitrate (Mbps) x number of cameras
Storage Required (TB) = (Average Bandwidth(Mbps) * Archive time (s) * % Activity) / ((1024 x 1024) x 8))
Alternatively calculate per camera type and add the results

12. POTENTIAL STORAGE LOSSES
OS and Application (on SSD for SL machines)
Internal Disk firmware, file system, boot data, shadow files and formatting
Base10 vs Base2 losses
OS calculates using Binary and HDDs using Decimal. This means that for example an 8TB disk will show as KB / (1024 x 1024 x 1024) = 7.45 TB in Windows
As a rule of thumb allow 10% total losses on the RAW storage after RAID applied to be safe

13. A LOOK AT SOME INDUSTRY CALCULATORS
We have yet to find a good processing and storage calculator
You are most likely to use an off the shelf calculator to do the maths so here are some things to look out for

14. SECURE LOGIQ DESIGN QUESTIONNAIRE

15. SUMMARY Use a calculator you trust
Compare calculator results with results achieved
Remember that different VMS’s may require different server configurations even if the total storage requirement is the same
Always allow a little extra, it is easy to soak up spare capacity by offering customers more than you quoted, the opposite is not true and upgrading a server in situ has an associated cost and can cause issues
If in doubt, ask the experts!!!!