Using avisynth to fade out the audio

[pooksahib]

Hi. I've a couple of conversions to do where an audio fadeout would be nice. I thought this would have been fairly easy but apparently not – seems the 'official' fadeout method also affects the video which is not what I want:
http://avisynth.nl/index.php/Fade
However, I found a function elsewhere on this forum:

function AudioFadeOut(clip input, int "num_frames")
{
num_frames = Default(num_frames,50)
FadeOut0(input,num_frames)
FadeOut0(last,num_frames)
FadeOut0(last,num_frames)
FadeOut0(last,num_frames)
return AudioDub(input,last)
}
and it works but not, in my experience, perfectly. Instead of fading to the end, it leaves a few seconds of silence at the end of the new video i.e. it fades to silence too early. Does anyone know of a method for achieving true 'fade to end' of the audio? Thank you.

[jagabo]

If you want a linear fade call FadeOut0() only once.

[pooksahib]

Perfect, thanks so much jagabo. The chap who wrote that function said of it "Note that I do repeated fades, as I want to have a very steep fade." I wonder why he just doesn't change the default, as I did, from 50 to 200 which gives me an 8 second fade. Thanks again, you're a pal.

[jagabo]

Here's an image of audio faded over 5 frames with FadeOut0(5):



As you can see it fades linearly from full amplitude at the left, to zero amplitude at the right (before the fade it was full amplitude across the entire image). But after four consecutive FadeOut0(5) you get a much steeper drop at the start:

[LigH.de]

Yes, I remember, overlaying several fades produces an effect like a logarithmical fade which is closer to the subjective loudness impression.

Linear: 100% - 80% - 60% - 40% - 20% - 0%

Logarithmic: 1 - 1/2 - 1/4 - 1/8 - 1/16 - 1/32

Multiple linear fading is not the same as logarithmic. But try 2 or 3 instead if 4 were too steep. Until maybe someone creates other non-linear volume change functions for AviSynth (I doubt Animate("AmplifydB") will work well on the audio part, due to video frame granularity).

[pooksahib]

Thanks guys. I much prefer my linear fade...

[raffriff42]

If anybody's interested, I hacked up the four main types of fadeout --
(I say "hacked" because they are piecewise approximations, not true curves, but they seem to work alright)
They're mainly for audio, but you can fade video only, audio-only, or both. Fade to black or any other color.

Script is here (dropbox)

Linear (the normal Avisynth fade):


Exponential (fast at first, then a long fadeout):


Studio (slow, medium, slow):


Logrithmic (slow, fast):


EDIT - an example:

Fade_stu(1999, 2029, vfade=false) # afade=true (default)
## "studio" fadeout
## audio fade only
## fade starts at frame 1999
## fade completed at frame 2029 (30 frames later)
## clip continues silent to the end

[pooksahib]

Looks like a lot of work went into that, raffriff42...

[raffriff42]

Looks like a lot of work went into that, raffriff42...

Yeah, no doubt. It was a fun little project.

[Anonymous344]

Thanks, raffriff42! This thread is related and might interest you.

[skh]

hello you guys,
I was looking for a very easy way to easily Audio only fade in and fade out each segment within an easy trim section. For example like this

Fade=30
#Trim(0,1000).FadeAudioIn(Fade).FadeAudioOut(Fade) ++ \
#Trim(2000,3000).FadeAudioIn(Fade).FadeAudioOut(Fa de) ++ \
#Trim(8000,0).FadeAudioIn(Fade).FadeAudioOut(Fade)

the video already contains fadein and fadeouts and I don't want to extend theese/black out more frames. So audio only would be ideal in this case to make everything more smooth and not so appruptley. raffriff42 function https://github.com/raffriff42/AvisynthPlusUtilities/blob/master/Utils-r42.avsi sounded perfect but I have no idea how to implement that into my logic. thanks in advance for your help

[skh]

I figured it out a bit but it applies the fades to the video too sadly

Trim(0,1996).UUFadeAV(Fade,Fade)++ \
Trim(4356,15840).UUFadeAV(Fade,Fade)++ \
Trim(19419,24070).UUFadeAV(Fade,Fade)++ \
Trim(27601,0).UUFadeAV(Fade,Fade)

[skh]

hmm it could be that the difference modes used in the no longer available Fade_stu are not a part of the posted Utils-r42.avsi
did anyone back that up as it is no longer online

[jagabo]

I figured it out a bit but it applies the fades to the video too sadly

Trim(0,1996).UUFadeAV(Fade,Fade)++ \
Trim(4356,15840).UUFadeAV(Fade,Fade)++ \
Trim(19419,24070).UUFadeAV(Fade,Fade)++ \
Trim(27601,0).UUFadeAV(Fade,Fade)

Use AudioDub() to apply the faded audio to the original video.

vid = last # remember original video
(apply your fades here)
AudioDub(vid, last)  # restore original video

[videoAI]

Try Clever-FFmpeg-GUI

[skh]

vid = last # remember original video
(apply your fades here)
AudioDub(vid, last) # restore original video
[/CODE]

I did some function madness to separate the audio so the fading was only applied on the audio and I didn't had to do multiple trim jobs but cannot recomment it. The fading worked great but everything was out of synch. So jagabos approach makes the most sense for theese trim jobs.
to keep the double logic somewhat automated what I ended up doing was this:

TrimStart1 = 0
TrimEnd1   = 1996

TrimStart2 = 4356
TrimEnd2   = 15840

TrimStart3 = 19419
TrimEnd3   = 24070

TrimStart4 = 27601
TrimEnd4   = 0  

Fade = 12
V = FFVideoSource("-")
A = FFAudioSource("-")
AudioDub(V,A)

video = V.Trim(TrimStart1, TrimEnd1) ++ V.Trim(TrimStart2, TrimEnd2) ++ V.Trim(TrimStart3, TrimEnd3) ++ V.Trim(TrimStart4, TrimEnd4)
audio=AudioDub(V,A).Trim(TrimStart1, TrimEnd1).FadeIO(Fade) ++ AudioDub(V,A).Trim(TrimStart2, TrimEnd2).FadeIO(Fade) ++ AudioDub(V,A).Trim(TrimStart3, TrimEnd3).FadeIO(Fade) ++ AudioDub(V,A).Trim(TrimStart4, TrimEnd4).FadeIO(Fade)
FINAL = AudioDub(video, audio)

This works and video is in synch with the audio and you only have to type your frame ranges once on top