Adaptive Silence Detection

Detect silent segments in video or audio files.

Requires FFmpeg — see ffmpeg.md for how to invoke it in Remotion projects.

Step 1: Measure loudness with loudnorm

Use the loudnorm filter in JSON mode to get the EBU R128 integrated loudness and gating threshold for each file:

npx remotion ffmpeg -i public/video.mov -map 0:a -af loudnorm=print_format=json -f null /dev/null

As output you will get:

• input_i: Integrated loudness (dB) — the overall perceived volume
• input_thresh: EBU R128 gating threshold (dB) — the level below which audio is considered too quiet to count toward loudness measurement

Step 2: Detect silences using adaptive threshold

Pass the input_thresh value from step 1 as the noise parameter to silencedetect:

npx remotion ffmpeg -i public/video.mov -map 0:a -af "silencedetect=noise=${THRESH}dB:d=0.5" -f null /dev/null

Parameters:

• noise: The threshold below which audio is considered silent. Use input_thresh from step 1.
• d: Minimum silence duration in seconds. 0.5 is a good default.

Interpreting the output

The filter outputs pairs of silence_start and silence_end timestamps:

[silencedetect] silence_start: 0
[silencedetect] silence_end: 2.241021 | silence_duration: 2.241021
[silencedetect] silence_start: 38.77425
[silencedetect] silence_end: 39.619604 | silence_duration: 0.845354

Identifying leading and trailing silence

• Leading silence: Consecutive silence segments starting at or near 0. If the first silence_start is > 0.5s, there is no leading silence.
• Trailing silence: The last silence segment that extends to (or near) the end of the file. Compare the last silence_end with the file's total duration.

When multiple silences are nearly contiguous at the start or end (gap < 0.2s), treat them as a single leading/trailing silence block.

Using with Remotion's <Video> component

Apply the detected trim points using trimBefore and trimAfter (values are in frames):

import { Video } from "@remotion/media";
import { staticFile, useVideoConfig } from "remotion";

const { fps } = useVideoConfig();

<Video
  src={staticFile("video.mov")}
  trimBefore={Math.floor(leadingEnd * fps)}
  trimAfter={Math.ceil(trailingStart * fps)}
/>