g(t) = min(1, t / F), t ≥ 0, F > 0
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How does this tool work?
Add a fade-in and/or fade-out so sound appears or disappears gradually. Each duration can be set from 0 to 30 seconds and the result is generated locally as WAV.
Fade-in uses FFmpeg’s afade filter at the start of the track. For fade-out, the engine temporarily reverses the signal, applies an equivalent fade-in for the selected duration, then reverses the result again. A duration of 0 disables that fade. This page starts with a two-second fade at each end. Each duration can be set from 0 to 30 seconds, including fractional values. The envelopes are linear in amplitude; there is no exponential-curve selector. A fade longer than the file may never reach full gain within the available audio, and no silence is appended to complete it. When fades overlap, their gains multiply, potentially attenuating the entire short excerpt. Output is 16-bit PCM WAV, with duration preserved to sample precision rather than extended to match the ramps.
How to use this tool
Import the track
Choose the audio file to process.
Set both durations
Configure fade-in and fade-out independently from 0 to 30 seconds.
Listen before use
Download the WAV and check that both fades suit the rhythm of the material.
Audio fade-in and fade-out — Calculation reference
- g
- Amplitude ratio, dimensionless
- t
- Elapsed time in seconds
- F
- Fade duration in seconds, strictly positive
Use cases
Softer opening
Avoid a music bed or ambience starting abruptly.
Clean ending
Let a track disappear gradually when its natural ending does not fit the edit.
Edit preparation
Prepare clip edges before adding them to a larger production.
Examples
A two-second fade-in
Halfway through an amplitude ramp is not halfway through perceived loudness. Discrete samples introduce a small rounding difference.
Input
Linear fade-in lasting 2 s, observed at 1 sResult
Gain near 0.5, approximately −6.02 dBA clip shorter than its fade
The file remains one second long; it is not extended to let the envelope finish.
Input
1-second file, 2-second fade-in, no fade-outResult
Gain close to 0.5 at the endTips and best practices
- A short fade is useful for a technical cut; a longer fade becomes a more noticeable creative effect.
- A fade is not a crossfade between two files: it only changes one track.
- Trim the clip first when you need the fade-out to line up precisely with a new ending.
Sources and references
- FFmpeg project, FFmpeg Filters Documentation (opens in a new tab)Page in English
Frequently asked questions
Can I apply only a fade-in?
Yes. Set the fade-out duration to 0 seconds.
Does fading change the file duration?
No. It changes gain over time without adding extra duration.
Is this a crossfade?
No. This tool processes one track; a crossfade mixes the overlap between two tracks.
What if the fade is longer than my clip?
Only the portion of the ramp covered by existing samples is applied. Choose a shorter duration if you want the clip to reach full level before it ends.
Can the two fades overlap?
Yes. Their gains multiply in the overlap, which can leave the whole clip attenuated. This does not create a transition between two separate files.
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