[FFmpeg-user] silenceremove use

To ny tonynederpel at hotmail.com
Fri Feb 21 22:59:32 EET 2020

Made a wave file of the first (softest) thump with the -accurate_seek, -t and -ss
and one of the "relative" silence parts and as Ted suggested checked with showvolume:

ffplay -f lavfi -i “amovie=sample.wav,showvolume"
This way it's especially insightful to see the volume level of very short sounds.

thump -37.8dB  silence -48dB

Used this one in ffmpeg now:

the step from -38dB to -37dB already nibbles off the leading silence and 36ms of the first thump.
Going up to a certain threshold removs the first thump but silences of seconds are still left in.

As it seems with the silenceremove i can't differentiate between the relative silence and the louder

I discovered the "truncate silence" in audacity now. It gets it done and you can just type in
how long you want to leave silence in between sounds and leaves everything above threshold

Thanks anyway to Ted and Paul.
Van: ffmpeg-user <ffmpeg-user-bounces at ffmpeg.org> namens Ted Park <kumowoon1025 at gmail.com>
Verzonden: vrijdag 21 februari 2020 04:53
Aan: FFmpeg user questions <ffmpeg-user at ffmpeg.org>
Onderwerp: Re: [FFmpeg-user] silenceremove use

> Ideally, it would be, if the thumps and voice would have some space between them during playback (of the output file), like three seconds apart and little bit of silence at the beginning. At the end silence isn't necessary.
> Ffplay i don't have compiled but using the silenceremove arguments with ffmpeg removes everything up until right before the two thumps with threshold set at -38dB. The first thump is removed unfortunately. The silence between the two thumps and my voice unfortunately isn't removed.
> At -37dB only my voice is left and none of the thumps are unfortunately left in.


Oh, sorry I misunderstood, I thought you wanted all noise cut out. I don’t know if this will work better since you want to include signals that are not much stronger than the background noise level, but have you maybe tried filters that reduce noise, like maybe anlmdn, rather than one that trims time-wise? For keeping pauses between, I think passing in the number of seconds for start_silence will do that for silenceremove, and you can trim the beginning if needed. If you want silence rather than the existing background noise, you could use silencedetect and use the metadata to generate and insert silence between sounds.

Ted Park
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