COMPUTECH PRIVATE LIMITEDStart with four inputs
A planning calculation needs the number of camera streams, the average bitrate per stream, recording hours per day and the required retention in days. The calculator uses decimal storage units: one terabyte is one trillion bytes. Its mathematical recording total is cameras multiplied by bitrate in megabits per second, multiplied by one million divided by eight, multiplied by recording seconds and retention, then divided by one trillion.
Average bitrate is an assumption to verify
Video bitrate is affected by scene complexity and the selected encoding controls. A nominal setting or a quiet test view does not necessarily describe normal operation. Manufacturer guidance distinguishes average, variable and maximum bitrate controls and explains why they behave differently. Measure a representative period or justify the planning value for the actual equipment. [1]
Do not count on unverified motion savings
Recording fewer hours reduces the mathematical estimate, but a motion-recording assumption should be based on the real scene and the recorder settings. A busy view may record much more often than anticipated. Use continuous recording in the initial estimate when the duty cycle is unknown, and make the assumption visible.
Allow for more than the recording total
The calculator adds the headroom percentage selected by the user. This is a planning allowance, not a universal engineering standard. Audio, additional streams, metadata, filesystem overhead and other recording duties are not automatically included. Write them into the design brief where they apply.
Keep RAID separate from retention
Raw disk capacity and the usable capacity of a resilient array are not the same. Our tool offers simplified RAID arithmetic only. Actual recorder support, supported drive sizes, filesystem limits, formatting overhead, spare drives and rebuild behaviour need a product-specific design. RAID is also not a replacement for a separate backup where one is required.
Confirm the design through commissioning
Record the bitrate settings, recording schedule, usable capacity and intended retention in the handover document. Review actual retained footage and warning behaviour after representative operation. A useful acceptance process tests retrieval as well as capacity. Future camera additions require the calculation to be revisited.
Technical references
Check the documentation for your exact product and version when specifying a system.