How to extend the mp3 file

I am new to this forum. I am using Audacity to convert WAV file into MP3 file. The WAV file has 55 min recording, but when it is converted into MP3 file, it is truncated to 45 min. How do I extend the length of the MP3 file to the same length as the WAV file?

Please don’t forget to give us your Audacity version and version of Windows (see the pink panel at the top of the page).

The MP3 file may be getting truncated because you don’t have enough disk space to write the whole file.

Or you may have the first 45 minutes of the track selected and are using export selection by mistake.


Thanks for your reply. Sorry, I do not have the version of Audacity, as I now do not access of the computer (which has Windows 8).

Yes, this was my mistake. I open the WAV file with Audacity and “export” it into MP3 file. The MP3 files are always 45 min long, regardless the length of the original WAV files. What should I do instead of “exporting”, if I want to convert the WAV into MP3?

Please see my previous reply. Have you ensured you have enough disk space to write the MP3 file? Audacity uses up to about 1 GB of space to import the 55 minutes MP3 in the first place.

Have you ensured you use Export and not Export Selection?

You have to export, or use some other application to convert the file. You can try TAudioConverter.


The computer should have enough disk space. 1 GB should not be a problem.

I am sure I used “Export” not “Export Select”. Every file gets truncated to 45 min. I just could not figure out how to extend the length of the mp3 file.

How do you determine the length of the exported MP3? Is it really truncated ???

The problem here is that a .mp3 file really is just a sequence of individual MP3 packets (frames). There is no such thing as a “global” header in a .mp3 file. So the only reliable way to get the exact duration would be scanning through the entire file - which is slow! So what most program do is: The try to guess the duration from the file size. This works okay for CBR files, but for ABR/VBR files it only gives a rough estimate, for obvious reasons.

tl;dr: It’s quite possible your player shows a wrong duration for the MP3 file, while the file itself actually is “complete”.

A user can simply import the exported MP3 back into Audacity then they can find out the length.


But did he actually do it that way :question:

I know the mp3 files are truncated, because people complained that the lectures seem to stop abruptly.

If I convert the mp3 file back to wav file, the wav file will be incomplete. The original file will be lost, unless I save it in a different filename.

Audacity supplied by us does not do what you allege (truncate exported MP3 files when you have sufficient disk space to export the file).

Either you have a bogus version of Audacity, or a bogus version of lame_enc.dll, or you are making one of the mistakes we have pointed out. You can get Audacity 2.1.0 here: and you can read at how to install an MP3 encoder that works with Audacity.

You can always export as WAV and convert to MP3 with iTunes or TA Converter.