Apply BiQuad filter to wav at certian timespans

Questions involving a Windows version of FFmpeg.
Djketley
Posts: 8
Joined: Sat May 25, 2019 1:20 am

Apply BiQuad filter to wav at certian timespans

Post by Djketley » Sat May 25, 2019 1:23 am

Hello fellas, Quick question im trying to apply a BiQuad filter to a WAV file but i need it to be active in certain positions and durations only ive tried using the enable = between(t, 10, 30) but it seems BiQuad dosent support this feature? it has to just apply the filter to given segments and output a wav file any support with command line or an example would be greatly appreciated. thanks!

pandy
Posts: 200
Joined: Mon Feb 24, 2014 1:46 pm

Re: Apply BiQuad filter to wav at certian timespans

Post by pandy » Mon Jun 03, 2019 9:29 pm

Perhaps (not tested - just idea) you can split you source on two path, one unmodified, second with bi-quad filter than apply (not sure if possible) mixer and apply mixing with desired time characteristic (fading between sources).

richardpl
Posts: 54
Joined: Sat Aug 01, 2015 6:35 pm

Re: Apply BiQuad filter to wav at certian timespans

Post by richardpl » Wed Jun 05, 2019 8:05 am

Biquad filter support timeline, but you need recent ffmpeg.

pandy
Posts: 200
Joined: Mon Feb 24, 2014 1:46 pm

Re: Apply BiQuad filter to wav at certian timespans

Post by pandy » Thu Jun 06, 2019 5:22 pm

richardpl wrote:
Wed Jun 05, 2019 8:05 am
Biquad filter support timeline, but you need recent ffmpeg.
Are you sure? https://ffmpeg.org/ffmpeg-filters.html#biquad no trace on this in official documentation.

Btw thanks for sofalizer and for other useful things!

richardpl
Posts: 54
Joined: Sat Aug 01, 2015 6:35 pm

Re: Apply BiQuad filter to wav at certian timespans

Post by richardpl » Fri Jun 07, 2019 6:52 am

see

Code: Select all

ffmpeg -h filter=biquad

pandy
Posts: 200
Joined: Mon Feb 24, 2014 1:46 pm

Re: Apply BiQuad filter to wav at certian timespans

Post by pandy » Mon Jul 01, 2019 7:13 pm

Can't check - no timeline in my ffmpeg version ( a bit old but supporting fdkaac and can't compile anything new under https://github.com/jb-alvarado/media-autobuild_suite ) and Your suite https://github.com/rdp/ffmpeg-windows-build-helpers don't work to me either...

richardpl
Posts: 54
Joined: Sat Aug 01, 2015 6:35 pm

Re: Apply BiQuad filter to wav at certian timespans

Post by richardpl » Tue Jul 02, 2019 7:36 am

You need certain skills to be helpful to community in general.

pandy
Posts: 200
Joined: Mon Feb 24, 2014 1:46 pm

Re: Apply BiQuad filter to wav at certian timespans

Post by pandy » Tue Jul 02, 2019 6:40 pm

richardpl wrote:
Tue Jul 02, 2019 7:36 am
You need certain skills to be helpful to community in general.
lol - seem i have no OCD "to be useful/helpful to community in general" whatever it means.
Anyway appreciate your work, thank you.

Djketley
Posts: 8
Joined: Sat May 25, 2019 1:20 am

Re: Apply BiQuad filter to wav at certian timespans

Post by Djketley » Thu Jul 04, 2019 4:48 pm

Thanks for your help guys i ended up splitting the file into sections and applying the filter where needed and joining. Not very elegant but seems to work. Another question i have is im trying to completly cut a frequency range i tried using sinc but im still getting bleed and not a complete cut even with -180db which if memory serves me right is the lowest i can go. ive tried a bandreject which actually does completely cut the audio but its inverted. ive attached an image to demonstrate.

Blue should be where the audio is and where the audio is should be blue.
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pandy
Posts: 200
Joined: Mon Feb 24, 2014 1:46 pm

Re: Apply BiQuad filter to wav at certian timespans

Post by pandy » Thu Jul 04, 2019 7:00 pm

Djketley wrote:
Thu Jul 04, 2019 4:48 pm
Another question i have is im trying to completly cut a frequency range i tried using sinc but im still getting bleed and not a complete cut even with -180db which if memory serves me right is the lowest i can go. ive tried a bandreject which actually does completely cut the audio but its inverted. ive attached an image to demonstrate.

Blue should be where the audio is and where the audio is should be blue.
You can't expect from 2 pole IIR -180dB to get -180 you need to stack same filter 12 - 16 times in series (i.e. build equivalent of IIR filter with order 24 .. 32)
And you get idea of the bandreject filter exactly in opposite way - you need to specify center frequency and tell how wide filtering should be.

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