Camera storage and retention without the guesswork

Begin with the recording requirement

“Thirty days of video” sounds precise, but it is incomplete without the camera count, actual stream bitrate and recording schedule. Before choosing storage, decide which cameras record continuously, whether any record on events, and whether particular clips need to be held beyond ordinary retention.

In BlackSight’s design, appliance storage for software, models and a bounded working buffer is separate from the device or service retaining recordings. That separation is intended to let customers expand retention without treating every storage change as a replacement of the analysis computer.

Use a transparent calculation

For continuous recording, one megabit per second produces approximately 10.8 decimal gigabytes per day: 1,000,000 bits × 86,400 seconds ÷ 8 ÷ 1,000,000,000. Multiply that figure by the average bitrate, camera count and days retained.

The table assumes eight cameras, each averaging 4 Mb/s, recording continuously. These are planning examples, not a BlackSight appliance rating or a recommended final configuration.

Understand why the bitrate changes

Resolution alone does not determine the storage required. Camera bitrate controls, compression, frame rate and scene content affect the result. Axis’s camera documentation explains the image-quality tradeoff of compression and provides bitrate/retention controls as part of storage planning.

Measure representative periods rather than one quiet minute. Include opening and closing, busy activity, night mode and any lighting conditions that introduce noise. Audio, container overhead and additional streams also need to be accounted for where used.

Reference: Axis — camera documentation: bitrate, compression and storage controls

Raw capacity is not usable retention

A drive’s advertised capacity is not all available for recordings. Filesystem overhead, redundancy, operating reserves and held evidence can reduce usable space. Keep the units consistent: decimal TB and binary TiB describe the same bytes with different numbers.

A system also needs to explain what happens at the retention boundary. Normal recordings may expire, while a clip deliberately held for review needs a separate policy. Operators should be able to see the space consumed and understand which policy will take effect next.

Plan the interruption as well as the normal day

If recording storage is disconnected, a working buffer can provide a limited bridge. Its duration depends on the available space and current incoming bitrate. Test the actual outage, recovery and backlog behavior; do not translate “local buffer” into a promise that no recording can ever be lost.

For cloud retention, calculate sustained upload demand and confirm the recovery policy after an internet outage. Eight streams at the example 4 Mb/s require 32 Mb/s of video payload before protocol overhead. Other business traffic and catch-up transfers need room too.

What this means for a BlackSight pilot

The intended benefit is a storage choice matched to the customer’s retention requirement, with clear visibility into recording coverage and remaining capacity. Start with measured streams and a small test target, then verify playback and recovery before scaling.

BlackSight’s local, cloud and combined storage capabilities remain in development. Capacity estimates should be kept with the assumptions that produced them and revised when camera settings or operating conditions change.