Trim leading silence
job_fabac13ceace4b50The default behaviour, start only.
ffmpeg -i https://cdn.rendobar.com/assets/examples/sample.mp4 -af "silenceremove=start_periods=1:start_threshold=-50dB" -c:v copy -t 5 out.mp4audio filter
The FFmpeg silenceremove filter
Strips silent passages from audio, by threshold and minimum duration.
3 of 3 variants measured Measured 2026-08-20
The part that catches people
The default only trims silence from the START. Removing silence throughout needs stop_periods=-1, and that single argument is the difference between a filter that appears broken and one that works.
Measured, not described
Every row below is a real job. The same 1280x720 five-second H.264 source went through each variant, so the numbers are comparable to each other and to every other filter page on this site. Encode time is the FFmpeg step on its own, separated from the download and the upload.
| Variant | Encode | Output | Cost |
|---|---|---|---|
| Trim leading silence | 160 ms | 361.9 KB · 1280x720 | $0.0040 |
| Strip all silence | 150 ms | 360.0 KB · 1280x720 | $0.0016 |
| Aggressive gate | 133 ms | 342.1 KB · 1280x720 | $0.0015 |
The exact commands
Strip all silence
job_caf1265777b147bcstop_periods=-1 is the whole trick.
ffmpeg -i https://cdn.rendobar.com/assets/examples/sample.mp4 -af "silenceremove=start_periods=1:stop_periods=-1:stop_threshold=-50dB:stop_duration=0.5" -c:v copy -t 5 out.mp4Aggressive gate
job_a1e2b88fb8af43dbHigher threshold, shorter window.
ffmpeg -i https://cdn.rendobar.com/assets/examples/sample.mp4 -af "silenceremove=start_periods=1:stop_periods=-1:stop_threshold=-40dB:stop_duration=0.2" -c:v copy -t 5 out.mp4How these numbers were produced
Each variant was submitted to the Rendobar API as an ffmpeg job against the same public source file, and the response was recorded verbatim. Encode time is the API's own per-step timing for the FFmpeg step. Output size is the byte count of the file the job produced. Cost is what the job was actually billed.
Nothing here was estimated, and the whole set is re-runnable, so if a figure looks wrong it can be checked rather than argued about. The 72 variants behind this filter reference cost $0.193082 in total to measure.
Frequently asked questions
What does the FFmpeg silenceremove filter do?
Strips silent passages from audio, by threshold and minimum duration.
What is the most common mistake with silenceremove?
The default only trims silence from the START. Removing silence throughout needs stop_periods=-1, and that single argument is the difference between a filter that appears broken and one that works.
How long does silenceremove take to run?
On a 1280x720 five-second H.264 source, the fastest variant on this page (Aggressive gate) spent 133 ms inside FFmpeg. That figure is the encode step alone, measured separately from the download and the upload, so it is the filter's own cost rather than the round trip.
Do I need FFmpeg installed to use silenceremove?
Not with Rendobar. Every command on this page ran through the Rendobar API against a URL, with no local FFmpeg install and no server. The job id next to each row is the real job that produced the numbers.
Other filters, measured the same way
loudnorm Normalises perceived loudness to a target LUFS, following EBU R128. atempo Changes audio playback speed without changing pitch. volume Scales audio gain by a ratio or in decibels. afade Fades audio in or out over a duration, with selectable curve. aresample Converts audio sample rate, and can compensate for timestamp drift.
Run silenceremove without installing FFmpeg
Every command on this page ran through the API against a URL. No binary, no server.