Trim silence out of video automatically: the highlight cut

A shorter, watchable cut of a long recording, alongside the full original.

Long recordings of conversations are mostly waiting. Witness Pro can make a shorter cut with the dead air trimmed out and the talking kept, so someone can watch the substance without sitting through everything. Written by the developer of Witness Camera, so read it with that in mind; where another approach is better, it says so.

Short answer. Highlight export in Witness Pro (iPhone) makes a shorter cut of the rear camera's video with quiet stretches removed and the stretches where someone is talking kept. It measures the recording's own level in half-second windows, treats anything about 8 dB above that recording's quiet floor as speech, pads each kept stretch by a second, and joins stretches less than 2.5 seconds apart. It is produced in addition to, never instead of, the full recording, so the original stays intact. Silent or no-audio recordings produce no cut.

What it does

Produces a second, shorter video. The full original is always kept.
Keeps stretches where someone is actually talking, including at ordinary conversational volume, not only shouting.
Trims quiet gaps between them.

How it decides what is speech

Speech levels vary with microphone gain and distance, so a fixed volume threshold would drop quiet but important talk. Witness measures each recording against its own ambient floor.

The audio is analysed in half-second windows.
A window counts as active when it is about 8 dB above that recording's own quiet floor.
Each active stretch is padded by about a second on each side so a word at the edge is not clipped.
Stretches closer together than about 2.5 seconds are merged, to avoid jump-cuts.
Stretches shorter than about a second are treated as stray noise and dropped.

When it is useful

Interviews and recorded conversations you need to review quickly.
Sharing something watchable without asking a colleague or a lawyer to sit through an hour.
A rough first pass before editing.

Limits

It is automatic and imperfect. Check the cut against the original before relying on it.
If nothing rises above the recording's own floor, or there is no audio track, there is no cut.
The cut is derived from the rear camera video, and adds to how long the recording takes to finish assembling.
It is a Pro feature on iPhone. The Android Pro page has no highlight export at present.
A trimmed cut is a copy. The hashes and time-stamp describe the original.

Questions

Can Witness remove silence from a video automatically?

Yes, with Pro on iPhone. Highlight export produces a shorter cut with the quiet dead air trimmed and the talking kept, in addition to the full recording.

Does it change my original recording?

No. It is produced in addition to the full recording, which stays intact.

How does it tell speech from silence?

It compares each half-second of audio with the recording's own quiet floor and treats anything about 8 dB louder as speech, with padding and merging so words are not clipped.

Is it available on Android?

Not at present. Highlight export is an iPhone Pro feature.

Try it free

The free app includes this. Set it up and test it before you need it.

Get Witness Camera for Free Get it on Google Play

More Witness features explained

Written on 27 October 2026. Features and prices change. This is not legal advice.