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hpr1766 :: Sox of Silence

Using SOX to speed up and remove silence in a podcast

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Hosted by Ken Fallon on 2015-05-11 is flagged as Explicit and is released under a CC-BY-SA license.
sox, truncate silence. 2.
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Duration: 00:10:16


Many of you may be aware of the "truncate silence" filter in audacity. As I already use SOX to speed up my podcasts, I wanted to see if it could also remove silence as well. While the man page is detailed, it is difficult to follow.

Fortunately Jason Navarrete posted an excellent article on called The SoX of Silence which went through the process step by step

The Script

    # -S, --show-progress
    # -V verbose
    # tempo Change the audio playback speed but not its pitch. 
    # remix Select and mix input audio channels into output audio channels. 
    # remix - performs a mix-down of all input channels to mono.
    # silence Removes silence from the beginning, middle, or end of the audio.
    sox -S -v2 "${FILENAME}" "${FILENAME}-faster-${SPEED}.ogg" -V9 tempo ${SPEED} remix - silence 1 0.1 1% -1 0.1 1%


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Comment #1 posted on 2015-05-11 01:54:57 by Jon Kulp


okay so I was already listening to your episode at 1.5x speed and when you did the little demonstration to speed it up to 1.8 times it was really flying ha ha! I don't know what the actual speed would've been at that point (2.7x?) but I had to slow it back down to normal speed on my podcast app and listen again to get the true effect.

By the way I use Beyondpod with the Presto sound library and listen to nearly everything at 1.5x speed by simply adjusting the settings in the app. You can actually set a default playback speed for individual podcast feeds so that you always have the correct speed. I also listen at variable speed using Rockbox on my iPod fourth-gen. So I don't really need the variable speed to be built into the audio file, but I am intrigued by the silence truncation thing. Will definitely poke around with that a bit. Thanks for an interesting episode.

Comment #2 posted on 2015-06-12 16:53:20 by Urugami

Can it do this....

I've been using the Truncate Silence function in Audacity to do this, since I was doing some editing of podcasts before listening, but didn't start speeding things up until I started using Podkicker with the Prestissimo plug-in. Accelerated listening has really helped me catch up with a 3-month backlog of podcasts. :) Anyway, to the question... I played around with the sox silence command for a while, trying it out, and got it to work as you said, but what I could not do was to leave the leading silence alone. Man pages, help pages, reference pages, etc all assume you want to get rid of the leading silence, and show how to do that, but don't demonstrate how to skip the leading silence. Nothing I tried worked. Is that something you've tried to do?

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