ffmpeg how to cross fade two mp3 tracks

Written by John Riselvato - original link

In this section we’ll learn various useful audio filters specifically to audio but all filters will work on video as well. Since this is just an audio section, -af instead of -filter_complex unless multiple audio input sources are required. See question “How to use filters (-vf/-af vs -filter_complex)?” for more details.

Making a music mix? Easily cross fade each track with FFMPEG within seconds. Cross fading allows for a smooth fade in and out between two audio files. In this example a cross fade of 1 second is applied:

 $ ffmpeg -i input1.mp3 -i input2.mp3 -filter_complex "acrossfade=duration=00:00:01:curve1=exp:curve2=exp" output.mp3

acrossfade
    Indicates the filter name for crossfading

duration, d
    Indicates the duration of the cross fade effect

curve1
    Indicates the cross fade curve for the first input
curve2
    Indicates the cross fade curve for the first input

Although in this example, both cross fade curves are exp or exponential, FFMPEG support multiple curves but below are 6 recommended curves:

log
    Logarithmic

par
    Parabola

ipar
    Inverted parabola

losi
    Logistic sigmoid

cub
    cubic

nofade
    No fade applied

For more information on curves, visit: https://ffmpeg.org/ffmpeg-filters.html#afade