Choosing CCTV redaction software — the questions that matter

Until recently, redacting CCTV meant a video editor, an afternoon, and a lot of frame-by-frame masking. Now several tools will find and blur faces and plates automatically. They differ more than their websites suggest. Here are the questions worth asking before you choose one.

How is it priced, and does that fit how often you need it?

This matters more than anything else, because most organisations' demand is lumpy. A school might get three requests a year. A retail chain might get thirty in a month after a busy Christmas.

You'll mostly see three models:

• Per minute of footage. Fair on paper, but it punishes long clips, and you often can't tell how much footage you'll need until you've searched for it.
• Annual plans with a video allowance. Predictable if your volume is steady. An expensive commitment if it isn't, and you pay a year up front for requests that may never come.
• Per video, whatever its length. Simple to budget, and it matches how requests actually arrive: one request, usually one clip.

Work out what last year's requests would have cost under each model. Then ask whether there's a way to pay for a single video without a subscription, for the year you only get one.

Where does the footage go, and who processes it?

You're the controller of the footage. The redaction provider is your processor. So you need:

• a data processing agreement that names what they do with the footage and for how long
• to know where it's processed and stored (UK, EU, elsewhere) and by whom
• to know when it's deleted, and whether you can delete it yourself

If a tool runs entirely on your own machine, most of these questions go away, but then your own machine has to be up to it.

What does it detect, and how do you fix what it misses?

Faces and number plates are the baseline. Ask how it copes with small, distant, side-on and low-light faces, because that's what real CCTV looks like. More important still, ask what happens when detection misses something. You need to be able to add a box by hand and have it follow the person through the clip. You also need to be able to un-blur the requester when they've been caught by mistake.

Can you show your working?

If a requester complains to the ICO, you'll need to show what you did. Look for a redaction log: what was found, what was blurred, what was left visible and why, who reviewed it, and when it was released. A tool that just hands you an MP4 leaves that record to you.

How long before you can do your first one?

You'll most likely need the tool with a deadline already running. Can you sign up and redact a clip the same day, without an installer, a sales call or IT? Try that before you need it.

What does the requester receive?

A standard MP4 that plays on a phone. Not a proprietary format, not a player download, and not a watermarked trial export.

A quick checklist

• Pricing that fits your volume, including a one-off option
• A processing agreement, a known location, and deletion you control
• Manual correction that tracks through the clip
• A redaction log you can put on the file
• Same-day start
• A plain MP4 at the end

Any tool that ticks those will do the job. Pick on price, and on whichever you'd rather use at five o'clock on the day the month runs out.