How to widen the stereo
1. Drop an audio file you already have. A photo or a video is refused here. 2. Leave medium, or pick light or wide. 3. Press “Widen stereo” and download.
GustKit runs the FFmpeg extrastereo filter. Medium uses a difference of 2.5. Wide uses 4. A file that is already stereo grows the gap between left and right. A mono file has no gap, so it stays centered. MP3, WAV, M4A, OGG and FLAC stay in that type.
More difference, not a second copy
Mono to stereo copies one channel into both sides. The two sides still match, so the image stays in the center. Stereo to mono mixes them into one channel. This page does the opposite of that mix: it raises what is different. It is not a pan. Pan moves the balance toward one side.
The audio stays in this tab
FFmpeg runs in this browser. GustKit does not fetch audio from a link. Close the tab and the file is gone. Files up to the limit shown next to the button.
How to check the stereo width
1. Play the download next to the original, with headphones if you can. 2. A sound that lived on one side should sit farther out. Wide should push harder than light. 3. If the file type changed, you opened a different page.
Mono to stereo copies one channel into both sides. This page runs FFmpeg extrastereo and keeps the file type. A mono file stays centered. Nothing is uploaded.