1---
2name: silence-detection
3description: Adaptive silence detection for video/audio files using FFmpeg loudnorm and silencedetect
4metadata:
5  tags: silence, detection, trimming, ffmpeg, loudnorm, audio
6---
7 
8# Adaptive Silence Detection
9 
10Detect silent segments in video or audio files.
11 
12Requires FFmpeg — see [ffmpeg.md](./ffmpeg.md) for how to invoke it in Remotion projects.
13 
14## Step 1: Measure loudness with `loudnorm`
15 
16Use the `loudnorm` filter in JSON mode to get the EBU R128 integrated loudness and gating threshold for each file:
17 
18```bash
19npx remotion ffmpeg -i public/video.mov -map 0:a -af loudnorm=print_format=json -f null /dev/null
20```
21 
22As output you will get:
23- `input_i`: Integrated loudness (dB) — the overall perceived volume
24- `input_thresh`: EBU R128 gating threshold (dB) — the level below which audio is considered too quiet to count toward loudness measurement
25 
26## Step 2: Detect silences using adaptive threshold
27 
28Pass the `input_thresh` value from step 1 as the `noise` parameter to `silencedetect`:
29 
30```bash
31npx remotion ffmpeg -i public/video.mov -map 0:a -af "silencedetect=noise=${THRESH}dB:d=0.5" -f null /dev/null
32```
33 
34Parameters:
35- `noise`: The threshold below which audio is considered silent. Use `input_thresh` from step 1.
36- `d`: Minimum silence duration in seconds. `0.5` is a good default.
37 
38## Interpreting the output
39 
40The filter outputs pairs of `silence_start` and `silence_end` timestamps:
41 
42```
43[silencedetect] silence_start: 0
44[silencedetect] silence_end: 2.241021 | silence_duration: 2.241021
45[silencedetect] silence_start: 38.77425
46[silencedetect] silence_end: 39.619604 | silence_duration: 0.845354
47```
48 
49## Identifying leading and trailing silence
50 
51- **Leading silence**: Consecutive silence segments starting at or near 0. If the first `silence_start` is > 0.5s, there is no leading silence.
52- **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.
53 
54When multiple silences are nearly contiguous at the start or end (gap < 0.2s), treat them as a single leading/trailing silence block.
55 
56## Using with Remotion's `<Video>` component
57 
58Apply the detected trim points using `trimBefore` and `trimAfter` (values are in frames):
59 
60```tsx
61import { Video } from "@remotion/media";
62import { staticFile, useVideoConfig } from "remotion";
63 
64const { fps } = useVideoConfig();
65 
66<Video
67  src={staticFile("video.mov")}
68  trimBefore={Math.floor(leadingEnd * fps)}
69  trimAfter={Math.ceil(trailingStart * fps)}
70/>
71```
72