Muting and fading within the audio stream are not directly supported, but in your case, you can do it in these steps:
- Remove the first part of the audio with
trim 0.1
. (You could writetrim 4800s
as well, if your sample rate is 48000 Hz.) - Do the fade-in on what is now the start of the audio (0.10–0.14 of the original audio), with
fade 0.04
. - Prepend the audio with silence to make up for what you removed, with
pad 0.1
.
So, the complete command is:
sox infile outfile trim 0.1 fade 0.04 pad 0.1
By default, fade
uses a logarithmic fade curve starting at –100 dB. However, you can choose a different curve by specifying a letter directly after fade
, as in fade t 0.04
. There are t
for linear, q
for quarter-sine, h
for half-sine, p
for parabolic, as well as l
for logarithmic (the default, but in case you want to make it explicit).