Use the silenceremove filter. This removes silence from the audio track only – it will leave the video unedited, i.e., things will go out of sync
Its arguments are a little cryptic.
An example
ffmpeg -i input.mp3 -af silenceremove=1:0:-50dB output.mp3
This removes silence
- at the beginning (indicated by the first argument
1) - with minimum length zero (indicated by the second argument
0) - silence is classified as anything under -50 decibels (indicated by
-50dB).
Documentation:
FFMPEG silence remove filter
Also anyone looking to find the right value to classify silence as may wish to look into normalising their input audio volume to 0dB first, to do this in ffmpeg see this answer.
Edit
As pointed out by @mems, to detect whether your version of ffmpeg has the filter run
ffmpeg -hide_banner -filters | grep silenceremove
if you have the filter it’ll output something like
silenceremove A->A Remove silence