Create a silent mp3 from the command line

I am trying to create a silent / empty mp3 file of (x) seconds using the command line. Quite a simple task I thought!

It seems LAME is able to do something like this, but I am unable to find anything that leads to achieving this.

Has anyone been able to do something like this?

Solution

Disclaimer: This is a unix-oriented approach (although sox is cross-platform and should get it done on windows only as well).

You'll need sox - "the [cross-platform] Swiss Army knife of sound processing programs".
This wrapper perl script, helps you generate any seconds of silence: http://www.boutell.com/scripts/silence.html
```
$ perl silence.pl 3 silence.wav
```

silence.pl is quite short, so I include it here, since it's public domains:

#!/usr/bin/perl

$seconds = $ARGV[0];
$file = $ARGV[1];
if ((!$seconds) || ($file eq "")) {
        die "Usage: silence seconds newfilename.wav\n";
}

open(OUT, ">/tmp/$$.dat");
print OUT "; SampleRate 8000\n";
$samples = $seconds * 8000;
for ($i = 0; ($i < $samples); $i++) {
        print OUT $i / 8000, "\t0\n";
}
close(OUT);

# Note: I threw away some arguments, which appear in the original
# script, and which did not worked (on OS X at least)
system("sox /tmp/$$.dat -c 2 -r 44100 -e signed-integer $file");
unlink("/tmp/$$.dat");

Then just lame it:

$ lame silence.wav silence.mp3