Invert audio filter?

[Reel.Deel]

Hi there people,

Does anyone know of a way to invert the audio in AviSynth? I have searched but came up empty handed. I'm sure it's not a common thing people do but audio editors do have a way to invert (flip) the audio.

[Dogway]

Maybe Reverse().Killvideo()?

[StainlessS]

Clarification, You mean, +ve peaks become -ve, and -ve peaks become +ve ?
Yes.
(cant help, just dont think Doggy understood)

[Reel.Deel]

Maybe Reverse().Killvideo()?

That would reverse the audio. Audio invert (also known as polarity invert, phase invert and others) is more like the filter Invert() for video. It basically flips the waveform 180 degrees.

https://i.ibb.co/b2YmpG8/audioinvert.png

Edit
Clarification, You mean, +ve peaks become -ve, and -ve peaks become +ve ?


Yep.

[Dogway]

Ah yes, flip the waveform, basically you multiply the audio by -1.0. In this regard it's like amplifying negatively, Amplify() (http://avisynth.nl/index.php/AmplifydB) already has that built in I think. Amplify(-1) by the examples.

[StainlessS]

A=Colorbars
B=A.Amplify(-1.0)

A=A.Waveform_Filmstrip(window=1,under=true,SubSize=0.25)
B=B.Waveform_Filmstrip(window=1,under=true,SubSize=0.25)

StackVertical(A,B)

https://i.postimg.cc/7ZXMDBfC/test-00.jpg (https://postimages.org/)
Only showing 1 (upper) channel [the other channel was silent for that colorbars frame].

Good Dog. https://www.cosgan.de/images/smilie/tiere/n020.gif

[Reel.Deel]

Ah yes, flip the waveform, basically you multiply the audio by -1.0. In this regard it's like amplifying negatively, Amplify() (http://avisynth.nl/index.php/AmplifydB) already has that built in I think. Amplify(-1) by the examples.

Dang, now I feel like a dummy. I even updated the documentation for the avs+ page :o. I vaguely recall reading something but I kept looking for "invert audio avisynth" and the Amplify page does not come up on Google. Thanks Dogway!

[TCmullet]

Oh wow. THANK YOU all for asking and answering this! I've done audio inversion many times in CoolEdit and Audacity, but today is the first time I needed it for audio within Avisynth! I thought SURE it was there somewhere, but couldn't find any reference to it. Nice that Amplify allows negative values! It works! THANK YOU all! (Maybe the documentation for Amplify could be updated to inform of what a negative value does.)