Double amplitude
job_b1aafd2fc5cd4b0aLinear ratio, about +6 dB.
ffmpeg -i https://cdn.rendobar.com/assets/examples/sample.mp4 -af "volume=2.0" -c:v copy -t 5 out.mp4audio filter
The FFmpeg volume filter
Scales audio gain by a ratio or in decibels.
3 of 3 variants measured Measured 2026-08-20
The part that catches people
volume=2 is a linear ratio, volume=2dB is decibels, and they are very different amounts. A bare number doubles amplitude, roughly +6 dB. Boosting without a limiter afterwards clips.
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 |
|---|---|---|---|
| Double amplitude | 163 ms | 363.5 KB · 1280x720 | $0.0017 |
| Plus 3 dB | 157 ms | 363.5 KB · 1280x720 | $0.0015 |
| Halve | 150 ms | 363.6 KB · 1280x720 | $0.0018 |
The fastest variant here is not the smallest. Halve finished the encode in 150 ms, while Double amplitude produced the smallest file at 363.5 KB. Which one matters depends on whether you are paying for compute or for storage.
The exact commands
Plus 3 dB
job_2eefd64718ad40d7Explicit decibels, the safer spelling.
ffmpeg -i https://cdn.rendobar.com/assets/examples/sample.mp4 -af "volume=3dB" -c:v copy -t 5 out.mp4Halve
job_d0010f1e71b942dbAbout -6 dB.
ffmpeg -i https://cdn.rendobar.com/assets/examples/sample.mp4 -af "volume=0.5" -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 volume filter do?
Scales audio gain by a ratio or in decibels.
What is the most common mistake with volume?
volume=2 is a linear ratio, volume=2dB is decibels, and they are very different amounts. A bare number doubles amplitude, roughly +6 dB. Boosting without a limiter afterwards clips.
How long does volume take to run?
On a 1280x720 five-second H.264 source, the fastest variant on this page (Halve) spent 150 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 volume?
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. afade Fades audio in or out over a duration, with selectable curve. aresample Converts audio sample rate, and can compensate for timestamp drift. silenceremove Strips silent passages from audio, by threshold and minimum duration.
Run volume without installing FFmpeg
Every command on this page ran through the API against a URL. No binary, no server.