How to fade audio in and out
1. Drop one audio file. Video and pictures are refused on this page. 2. Leave 1 second on both sides, or set one side to None when you only need the other. 3. Press “Fade audio” and listen to the first second and the last second of the download.
FFmpeg uses afade. The fade-out starts near the end, using the length read from the file. If that length is missing, the end is faded by reversing, fading in, and reversing again. A fade longer than the clip is shortened so the two sides do not meet in the middle.
What changes, and what does not
The samples at the edges move toward silence. The middle is re-encoded at the same kind of audio: WAV stays WAV, MP3 stays MP3. This does not cut the timeline and it does not change the volume of the middle.
Trim audio can add a short fade while it cuts. This page is the one that fades a file you already want to keep whole. Change volume is the page for a louder or quieter file.
The file stays in this tab
The first visit downloads FFmpeg. Later visits reuse the browser cache. You can disconnect after that download finishes. GustKit does not keep the audio.
How to hear the fade before you replace the original
1. Play the first second of the download with the volume up. It should start quiet. 2. Skip to the last second. It should fall to silence. 3. If the middle sounds different, that is the re-encode, not a volume change. Keep the original until it sounds right.
None on one side leaves that edge as it was. A fade longer than the clip is shortened. Trim audio is the page that also cuts. Nothing is uploaded.