Batch remove silence from many MP3 files

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7 min. reading

I’ve downloaded over fifty one hour long recordings of my church-related celebrations. As with most of such recordings, every file contains about 5-6 minutes of:

  • silence or
  • non-related sounds

in the beginning during priest’s processing, people gathering etc. Plus it concludes some silence during various moments of celebrations. I wanted to get rid of it.

I found this eleven years old question at Super User. It’s not only very old, but also off-topic (no software recommendation-like questions allowed at SU) so I decided to put my own update here.

dBpoweramp Music Converter (dMC)

As in comments, this program is a joke! It’s user design is completely not user-friendly and counter-intuitive. I simply did not found any buttons, switches or controls related to actual silence trimming or using any other DSP effect. All I found was some list-related operations (select all etc.) plus batch conversion.

Both Super User answer and program’s website claims about using DSP effects, including silence trim, but there is no intuitive or easy to find entry into applying these filters in batch-processing mode.

Some links:

Batch Audio Silence Remover

On contrary to above, this program is very intuitive in use, but… so incredibly slow!

I didn’t even had a chance to test it in batch-processing mode. After waiting 15-20 minutes (!) and noticing that it is still analysing silence in my first file (and still not actually removing it), I simply gave up. I don’t have two years to process my fifty files especially given the fact that I have not so slow PC (8 GB, dual-core i3).

The program is no longer supported in terms that “Download” button on its homepage points to 404 error, so you have to download it from some other sources:

I haven’t got chance to validate all of these links. Some of them points to homepage only (and thus fails as well), but some of them allows you to actually download the file. If you have three years of spare time and want to give it a go.

Audacity batch

The original post (now 11 years old) said that you need a separate Nyquist Effect Plug-in to trim silence and that you can’t do that in batch processing. Eleven years later both statements are fortunately not true anymore.

The Truncate Silence effect is available in Effect > Truncate Silence… menu and you can use Batch Processing or Macros in order to process many times at once. If you learn how to use them because not many things are obvious and simple in Audacity.

Truncate Silence itself has a stupid design. You must have something selected. Even whole file must be selected with Ctrl+A. Effect plug-in is to stupid to work on entire file, if no selection is made and throws very irritating errors at you instead of actually doing its work.

When you pass that, it is quite easy to master and use, but the effects were far below my expectations.

With default settings:

Truncate Silence.png

It was cutting way too much. With some experiments I ended up with using Threshold = -50 dB and Duration = 2 seconds for detecting silence plus Truncate to: 2 seconds as an resulting action.

With such settings effects were far better, but I was still too frighten that an automatic job will cut too much. Plus, I didn’t master batch processing and decided to do this the ol’school time wasting, but much more reliable manual way.

Audacity manual

The program is developed by some open source freaks that strive to make single user interface for users of all three systems. Not direct Windows customisation causes that usage of Audacity is counter-intuitive, if you get used to other Windows programs. The same for Mac and Linux as a lot of people claims. And thus we have a typical stupid situation that open source tries to be best for all and turns out to be bad for every one.

Anyway, if you want to use Audacity keep these things in mind:

  1. It works on projects, not directly on files:
    1. While it can open such file, it opens it as a project.
    2. When you hit Ctrl+S you will be saving Audacity project, not a file that you have just modified.
    3. You must export it instead.
  2. Some moron decided that there will be only Ctrl+Shift+E keyboard shortcut for Export Audio option, but no for File > Export > Export as MP3.
  3. It is slow. Much faster than Batch Audio Silence Remover but you still need:
    1. 45 seconds for opening (importing) 1 hour long MP3 file
    2. 2 minutes for saving (exporting) it

It’s speed at least gives you a good file size reduction. It my case it was up to 30% smaller files produced out of Audacity when compared to original MP3 files.

Manual silence trim is, as mentioned, very time consuming, but gives you an absolute control on what is actually cut. If you have an automatic alternative that cuts only beginning and ending silence then this may work for you. If you have (as in case of Audacity effect) a solution that cuts everything through entire file then manual way may be the only option for you, because automated processing may simply cut too much.

Some other options

If nothing of above suites you then alternativeto.net is your friend as usual.

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