Display LENGTH in column

After several hours of fruitless research, I come to seek help here !

I have many files for which the ''Length'' column is empty. My goal is therefore to fill this column (or another) with the duration of each track (in miliseconds, it will be perfect).

I create a new Column New:

  • value: empty
  • Field: empty
  • Sort by: empty

I create a new action group

  • Name of group action: duration
    In this "duration", I create only one "action type": FORMAT VALUE

In Format Value I can't select my command (this is the first thing I don't understand)

  • So I select: Field = LENGTH
  • and FORMAT STRING = %_length_seconds%

I apply the actions, taking care to check only the "duration" action that I created.

Then, I select my audio files, and I click: Actions > Duration.

And nothing happens :wink:
Even the "Length" column does not change.

I have read the documentations and a bit the forum, but I can't find the solution.

Counting on your help,

Please note that LENGTH is a field that has no significance in respect to the length of a track as determined by the creating program.
The property for the length can be displayed with the variable_LENGTH.

If you create a column with

then it does not show any data.
If you want to see the length as found in the file header, use
value: %_length%
Please note, that the propery _LENGTH cannot be written my MP3tag.
if you want to see your user-defined field (which could contain anything), use
value: %length%
If you want to also modify this field in the column, then also fill
Field: %length%
More about the customization of the file list, see

For the files that you have treated with your action, check the extended tags dialogue Alt+T to see if a field LENGTH has been created.

If you have files where the column displaying the data from _LENGTH stays empty, then you have a file that has to be checked as it apparently has a broken header.

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If your files really don't show content for %_LENGTH% as @ohrenkino wrote above, I highly suggest to use the recommended programs here:

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Thank you for your help.
Ahhh, I understand that Mp3tag cannot calculate the length itself: the length must have been created beforehand by the MP3 creation software...
So I'm going to look on this side (maybe with an FFMPEG or FFPROBE command??)

I don't understand your intention.
Don't you have an existing file?
That will show the length but not in the field LENGTH but in the property that is shown with _LENGTH (with a leading underscore).

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Sorry for not being clear enough: my files are produced by a tool that uses the Google Text to Speech API. And it appears that the files do not include information on their duration.
By the way, all the files are tagged with "ERROR: MP3 header parse error".
This is why indeed, I think that the problem comes from there.

An MP3 without the proper information in the header is a broken file.
The error message indicates that.
In that case it would not make a difference whatever you added as tag data.
Please follow @LyricsLover 's advice and check the files for integrity first.
All further efforts are vain as long as the file is broken.

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Yes, I'm looking at this and I have contacted the developers of the tool that produces the MP3s. The solution is there.

Thanks again for your help everyone!

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