Question 1

Does changing speed affect audio quality?

Accepted Answer

Pitch-preserve mode re-encodes the audio, so there is a small quality reduction. At speeds between 0.5x and 2x this is minimal. Extreme speeds may introduce slight artifacts.

Question 2

Can I speed up audio without changing the pitch?

Accepted Answer

Yes. Enable the pitch-preserve option (on by default). This uses FFmpeg's atempo filter which changes tempo without affecting pitch.

Question 3

What is the maximum speed change?

Accepted Answer

The slider goes from 0.25x to 4x. Speeds above 2x or below 0.5x chain two atempo passes to stay within FFmpeg's filter limits.

Question 4

Are my files uploaded to a server?

Accepted Answer

No. All processing runs in your browser using WebAssembly. Your files never leave your device.