Fade in 2s
job_c23ddee0f613400bDefault triangular curve.
ffmpeg -i https://cdn.rendobar.com/assets/examples/sample.mp4 -af "afade=t=in:st=0:d=2" -c:v copy -t 5 out.mp4audio filter
The FFmpeg afade filter
Fades audio in or out over a duration, with selectable curve.
3 of 3 variants measured Measured 2026-08-20
The part that catches people
The default curve is triangular, which sounds abrupt on music. exp or qsin is usually what people actually want, and the curve argument is the one most tutorials omit entirely.
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 |
|---|---|---|---|
| Fade in 2s | 155 ms | 363.5 KB · 1280x720 | $0.0016 |
| Exponential fade in | 148 ms | 356.3 KB · 1280x720 | $0.0017 |
| Fade out at 4s | 156 ms | 363.6 KB · 1280x720 | $0.0015 |
The exact commands
Exponential fade in
job_17cc8443c25d40e2Smoother onset for music.
ffmpeg -i https://cdn.rendobar.com/assets/examples/sample.mp4 -af "afade=t=in:st=0:d=2:curve=exp" -c:v copy -t 5 out.mp4Fade out at 4s
job_f287bf1d188e44f8Quarter-sine, a gentle tail.
ffmpeg -i https://cdn.rendobar.com/assets/examples/sample.mp4 -af "afade=t=out:st=4:d=1:curve=qsin" -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 afade filter do?
Fades audio in or out over a duration, with selectable curve.
What is the most common mistake with afade?
The default curve is triangular, which sounds abrupt on music. exp or qsin is usually what people actually want, and the curve argument is the one most tutorials omit entirely.
How long does afade take to run?
On a 1280x720 five-second H.264 source, the fastest variant on this page (Exponential fade in) spent 148 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 afade?
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. aresample Converts audio sample rate, and can compensate for timestamp drift. silenceremove Strips silent passages from audio, by threshold and minimum duration.
Run afade without installing FFmpeg
Every command on this page ran through the API against a URL. No binary, no server.