Fade a Video In and Out

Fade a video in from black and out to black

Use this tool to soften how a clip starts and ends. The picture ramps up from a solid colour — black by default — at the beginning, and ramps back down to that colour at the end. The sound ramps out of and into silence over exactly the same spans, so the two never drift apart. Set either side to 0 to skip it, pick a different fade colour, or restrict the fade to just the picture or just the sound. Everything runs in your browser and nothing is uploaded.

Worked example: load a 10-second intro.mp4, set Fade in to 1, Fade out to 1, and Exact clip length to 10. The first second lifts the picture out of black while the audio rises from silence; the last second (starting at 10 − 1 = 9 s) sinks both back down. The result is a 10-second intro-fade.mp4 — same length, same footage, softer ends.

Why the clip length is asked for

A fade-out has to be placed at an absolute time: clip length − fade out. The plan is built before the file is decoded, so the length can't be read off the video first — type it in the Exact clip length box (your player's total-time readout is the number you want). A fade-in always starts at 0, so a fade-in-only run needs no length at all; leave the box at 0.

What each control does

• Fade in / Fade out — length in seconds of each ramp, 0 to 30. At least one of the two must be above 0; both at 0 is rejected as a no-op. Their sum may not exceed the clip length.
• Fade — Picture and sound (default), Picture only (audio stays at full level), or Sound only (the picture is stream-copied untouched).
• Fade colour — any colour the ffmpeg filter accepts: a name (black, white), a hex value (#101820 or 0x101820), or name@alpha such as [email protected]. Ignored when you fade sound only.
• Output quality — the H.264 CRF used for the re-encoded picture: high (18), balanced (23, the default), or small (28). A lower number keeps more detail and produces a larger file.

Notes and limits

• Fading the picture rewrites pixels, so that path re-encodes to H.264/AAC in an MP4 regardless of the input container. Quality loss is normal re-encode loss; pick high quality if the source is precious.
• Sound only is the lossless path: the video stream is copied bit-for-bit and the input container is kept (mp4 → mp4, webm → webm). WebM audio is written as Opus, everything else as AAC.
• Each fade is capped at 30 seconds per side, and the clip length at 10 hours.
• Input and output are each capped at 25 MB, because ffmpeg runs inside the browser tab rather than on a server.
• The ramps are linear. The picture fade filter has no easing/curve option at all, so a curved audio ramp would no longer match the picture.
• This fades one clip against a flat colour. It does not cross-dissolve between two clips, and it does not fade an alpha channel — H.264 in MP4 has no transparency to fade.
• If the length you type is wrong, the fade-out lands in the wrong place: too large and it starts late (or gets cut off by the real end), too small and it finishes before the clip does.

FAQ