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How to automatically truncate silence-like parts?

Posted: Sat Sep 16, 2017 8:27 am
by vitaly-zdanevich
Good day to everyone. I use Audacity pretty often - mainly for clearing/adjusting of my recorded lectures. With my last record I faced with a problem that this six hours file has many little silence-like parts. On parts that larger than 100ms I can use `Silence Finder` and manually delete it. But what about smaller parts and that not exactly pure silence? I believe that such parts can be algorithmically identified. Maybe exists some plugin for such task or I can write myself? Thank you for support.
audacity-silence-waveform-db.png
Waveform dB
audacity-silence-waveform-db.png (53.09 KiB) Viewed 762 times
audacity-silence-waveform.png
audacity-silence-like
audacity-silence-waveform.png (37.48 KiB) Viewed 762 times
audacity-silence-waveform-db.png
Waveform dB
audacity-silence-waveform-db.png (53.09 KiB) Viewed 762 times

Re: How to automatically truncate silence-like parts?

Posted: Sat Sep 16, 2017 4:38 pm
by Trebor
vitaly-zdanevich wrote: I faced with a problem that this six hours file has many little silence-like parts.
aka Skips ... http://manual.audacityteam.org/man/faq_ ... cations.3F
vitaly-zdanevich wrote:Maybe exists some plugin for such task
It's built-in ... Truncate silence

There will probably be clicks where the silences have been removed : you may need a DeClicker plugin.

Re: How to automatically truncate silence-like parts?

Posted: Sun Sep 17, 2017 8:06 am
by vitaly-zdanevich
`Truncate Silence` is not an option for such case - because as you can see on the screenshots - this `silence-like` parts in reality a noise-like parts - that is not more quiet than some natural correct silence. Maybe exists some plugin with functionality like inside Noise Reduction - where I can take `profile` (example) and take next actions with such example in mind?

Re: How to automatically truncate silence-like parts?

Posted: Sun Sep 17, 2017 1:50 pm
by Trebor
vitaly-zdanevich wrote:`Truncate Silence` is not an option for such case - because as you can see on the screenshots - this `silence-like` parts in reality a noise-like parts ...
"Truncate silence" doesn't just work on true flat-line silence.
You set a threshold on "Truncate silence" : anything below that threshold will be treated as silence.

Before you use "Truncate silence" use "Normalize" to remove the small DC offset you've got ...
flat-line is not on zero = 'DC offset'.png
flat-line is not on zero = 'DC offset'.png (77.4 KiB) Viewed 742 times

Re: How to automatically truncate silence-like parts?

Posted: Sun Sep 24, 2017 7:45 am
by vitaly-zdanevich
Thank you!

I found that normalize with removing of DC offset just increase DC offset, so I search the web about how to fix DC offset and found a solution - High Pass Filter (90Hz, Rolloff: 6dB) that remove low-frequency noise (so as I understand - on my screenshots was not a DC offset but that noise). And after that Truncate Silence - works like a magic. For the last week I lost few hours for manually removing of that silence and after that - manually removing of new clicks using selection in spectral view.

Thank you again!