Video Redaction (Manual Application) – DekkoDEMS knowledge base

DekkoDEMS can redact video evidence directly in your browser: black out sensitive details on screen, trim the footage to just the relevant clip, and silence spoken details in the audio. The result is a separate redacted copy - the original recording is never altered.

Redaction runs on Dekko EdgeAI and is processed entirely on your device. Nothing is sent to a cloud service; the redacted copy is saved into your case or downloaded from your own browser directly to your device.

This article covers manually drawing black boxes (Draw black box and Black box current frame) and audio muting. To have DekkoDEMS find and track faces for you, see Redacting Footage: AI Face Detection.

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Redact footage is an Early Preview feature, and the output is a draft. Always verify the redacted copy against the original recording before sharing it - step through it and confirm every sensitive detail is covered for the full time it is on screen.

Before you start

Redaction is available on any uploaded MP4 video file - you can redact whether or not the file has been transcribed.

Open it from the file's ··· menu (or the More dropdown) and choose Redact footage.

Choose what stays in the copy

The timeline at the bottom of the editor controls which part of the video the redacted copy contains:

Drag the Start and End handles to select the clip. Anything outside the range is cut out of the copy entirely (shown greyed/hatched on the timeline and in the filmstrip).

The redacted copy is a new, separate file (for example carchase.redacted.mp4) containing only the selected clip, with your redactions burned in.

The legend shows what each part of the timeline means: Stays in the copy (blue), Cut out (grey), Audio muted (red).

Use the playback controls (Play, frame step, 10s Back/Forward) and drag the playhead to find the moments you need. The Final redacted output filmstrip previews exactly how the copy will look.

Draw a black box

Use these tools under Put black boxes on sensitive details:

Move the playhead to the moment where the sensitive detail appears.

Choose a tool:

Draw black box - the box covers the whole selected clip range (for example, a screen, a licence plate fixed in frame, or a bystander who stays in one place).

Black box current frame - the box covers only the frame currently shown (for a detail visible in a single frame).

Draw the box over the detail on the video preview.

Check the filmstrip and step through the frames to confirm the box covers the detail for as long as it is visible. If the subject moves, add more boxes, or use Follow face with a black box (see the AI Face Detection article).

Boxes can be removed before export, but once exported they are permanent black boxes in the redacted copy — the underlying pixels are not recoverable from that file. (The original file in the case is untouched.)

Mute audio

Use the Audio section to silence spoken details such as names and addresses:

Mute from here - play to the spot where the detail is spoken, then mark the span to silence.

Remove all audio - strips the entire audio track from the redacted copy.

Muted spans show in red on the timeline.

Export the redacted copy

When you're happy with the preview:

Create redacted copy in case - saves the redacted file alongside the original in the case.

Download redacted copy - saves it to your device instead.

You can also export a single frame with redactions burned in: Save current frame in case or Download current frame (top of the panel).

Good to know

The original is never modified. Redaction always produces a separate output file; the source recording stays intact in the case.

Redactions apply to the area you specify - a box only covers what you draw it over, for the range you chose. Review the whole clip to make sure nothing sensitive slips past the box.

Trim first. Setting the clip range before adding boxes keeps the preview, and the output, focused on what you actually intend to disclose.

FAQ

Does the video leave my device during redaction? No. Processing runs on-device in your browser. The redacted copy is created locally, then saved into the case or downloaded.

Does redacting change the original file? No. The output is a separate file (for example filename.redacted.mp4) containing only the selected clip with the redactions applied.

Can someone recover what's under a black box? Not from the redacted copy — boxes are burned in permanently on export. The unredacted original remains in the case for authorised users.

Can I redact just part of a long video? Yes. Drag the Start and End handles so only that section stays in the copy; everything else is cut out.

Can DekkoDEMS find faces for me? Yes - see Redacting Footage: AI Face Detection for Find faces and Follow face with a black box.