[FFmpeg-user] Audio filter: removesilence doesn't appear to do anything

[Quinn Wood]

I have used the following command
    ffmpeg -i input.m4a -af silenceremove=0:0:0:-1:0.5:-20dB output.m4a

on a file. When I use another tool (Audacity) to truncate periods over
0.5 seconds of under -20dB volume it removes upwards of an hour from
the input file. When I run this command ffmpeg doesn't remove a single
second. I have tried numerous variations of the command and numerous
input files, and am simply unable to replicate the effect Audacity is
producing.

The input files have a period of silence at the beginning that is
predictable, intermittent periods of silence throughout the file of
unknown quantity and length, and a period of silence at the end that
is predictable.