Get length of .wav from sox output

Question

I need to get the length of a .wav file.

Using:

sox output.wav -n stat

Gives:

Samples read:            449718
Length (seconds):     28.107375
Scaled by:         2147483647.0
Maximum amplitude:     0.999969
Minimum amplitude:    -0.999969
Midline amplitude:     0.000000
Mean    norm:          0.145530
Mean    amplitude:     0.000291
RMS     amplitude:     0.249847
Maximum delta:         1.316925
Minimum delta:         0.000000
Mean    delta:         0.033336
RMS     delta:         0.064767
Rough   frequency:          660
Volume adjustment:        1.000

How do I use grep or some other method to only output the value of the length in the second column, i.e. 28.107375?

Thanks

score 60 · Answer 1 · edited Apr 15 '12 at 14:49

60

There is a better way:

soxi -D out.wav

edited Apr 15 '12 at 14:49

answered May 25 '11 at 07:00

Andrew Kuklewicz

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Unfortunately it returns wrong duration, distinguish from `sox output.wav -n stat` method in my case. – Ivan Kochurkin Mar 09 '13 at 10:47
I have never seen it to be wrong - can you distinguish in what situation this is incorrect? – Andrew Kuklewicz Mar 13 '13 at 17:04
I've cropped the audio with http://mp3cut.net/ and got the warn from sox: `WARN mp3-util: MAD lost sync` with wrong duration. On the other hand `sox output.wav -n stat` execution returns correct duration in error output thread (see my answer for explanation). Also windows explorer shows correct duration. – Ivan Kochurkin Mar 13 '13 at 22:30
FWIW - I've used this method on linux and mac for years without any such issue - sounds windows specific. – Andrew Kuklewicz Oct 30 '13 at 07:24
4

I think the two differ in that soxi uses the header info, while sox looks at the body, too. SO if the header is wrong, the two give different outpu. – Ruprecht von Waldenfels Dec 23 '14 at 12:16
@RuprechtvonWaldenfels Interesting theory. Can anyone confirm this? I can't see anything on a quick glance at the man pages. – Matthias Jul 08 '16 at 14:43
1

Why theory? Man directly states it [for `soxi` (`sox --info`)](https://linux.die.net/man/1/soxi): "Displays information from the header of a given audio file or files.", [for sox stat](https://linux.die.net/man/1/sox): "Display time and frequency domain statistical information about the audio. Audio is passed unmodified through the SoX processing chain." You could read further how it statistics collected and calculated also. – Hubbitus Jun 14 '17 at 20:52

score 42 · Accepted Answer · edited Mar 13 '13 at 08:56

42

The stat effect sends its output to stderr, use 2>&1 to redirect to stdout. Use sed to extract the relevant bits:

sox out.wav -n stat 2>&1 | sed -n 's#^Length (seconds):[^0-9]*\([0-9.]*\)$#\1#p'

edited Mar 13 '13 at 08:56

Thor

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answered Dec 26 '10 at 16:07

phihag

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I've got no idea how you constructed this, but it works like a charm. Thank you! – joshu Dec 26 '10 at 18:47
For what it's worth, using sox v14.0.0 on Windows, the $ (EOL) marker caused this answer to fail to give the result expected (instead of parsing to the end of line, it simply parses till it finds something which isn't a digit or period. – MrCranky Aug 04 '12 at 10:35
2

This is more reliable than `soxi`: this one involves traversing the audio file to _calculate_ the length whereas `soxi` simply reports what is in the header - regardless of accuracy – WestCoastProjects Apr 21 '20 at 21:21

score 14 · Answer 3 · answered Nov 11 '12 at 14:18

14

This can be done by using:

soxi -D input.mp3 the output will be the duration directly in seconds
soxi -d input.mp3 the output will be the duration with the following format hh:mm:ss.ss

answered Nov 11 '12 at 14:18

Hadi Salem

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Dragonfly · Answer 4 · 2012-07-12T13:36:37.630

7

This worked for me (in Windows):

sox --i -D out.wav

edited Jul 12 '12 at 13:36

answered Jul 11 '12 at 21:25

Dragonfly

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Unfortunately it returns wrong duration, distinguish from `sox output.wav -n stat` method in my case. – Ivan Kochurkin Mar 09 '13 at 10:48
stat returned 139.389388 and this returned 139.407007. For my purposes it's OK. Thanks. – ed22 Sep 08 '17 at 11:09

score 4 · Answer 5 · answered Apr 25 '14 at 18:38

4

I just added an option for JSON output on the 'stat' and 'stats' effects. This should make getting info about an audiofile a little bit easier.

https://github.com/kylophone/SoxJSONStatStats

$ sox somefile.wav -n stat -json

answered Apr 25 '14 at 18:38

Kyle Swanson

93
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score 2 · Answer 6 · answered Oct 11 '18 at 11:03

2

for ruby:

string = `sox --i -D file_wav 2>&1` 
string.strip.to_f

answered Oct 11 '18 at 11:03

urbanczykd

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score 1 · Answer 7 · answered Mar 09 '13 at 19:30

There is my solution for C# (unfortunately sox --i -D out.wav returns wrong result in some cases):

public static double GetAudioDuration(string soxPath, string audioPath)
{
    double duration = 0;
    var startInfo = new ProcessStartInfo(soxPath,
        string.Format("\"{0}\" -n stat", audioPath));
    startInfo.UseShellExecute = false;
    startInfo.CreateNoWindow = true;
    startInfo.RedirectStandardError = true;
    startInfo.RedirectStandardOutput = true;
    var process = Process.Start(startInfo);
    process.WaitForExit();

    string str;
    using (var outputThread = process.StandardError)
        str = outputThread.ReadToEnd();

    if (string.IsNullOrEmpty(str))
        using (var outputThread = process.StandardOutput)
            str = outputThread.ReadToEnd();

    try
    {
        string[] lines = str.Split(new string[] { Environment.NewLine }, StringSplitOptions.RemoveEmptyEntries);
        string lengthLine = lines.First(line => line.Contains("Length (seconds)"));
        duration = double.Parse(lengthLine.Split(':')[1]);
    }
    catch (Exception ex)
    {
    }

    return duration;
}

score 0 · Answer 8 · answered Feb 11 '14 at 11:30

0

In CentOS

sox out.wav -e stat 2>&1 | sed -n 's#^Length (seconds):[^0-9]([0-9.])$#\1#p'

answered Feb 11 '14 at 11:30

dkapa

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score 0 · Answer 9 · answered Jun 02 '15 at 15:57

sox stat output to array and json encode

        $stats_raw = array();
        exec('sox file.wav -n stat 2>&1', $stats_raw);
        $stats = array();

        foreach($stats_raw as $stat) {
            $word = explode(':', $stat);
            $stats[] = array('name' => trim($word[0]), 'value' => trim($word[1]));
        } 
        echo json_encode($stats);

Get length of .wav from sox output

9 Answers9

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