15 Feb
2020
15 Feb
'20
12:24 a.m.
Hi
I've written a python script to do crossfades loops in samples. First version was
using commandline tools, but updates of the underlying tools broke my script, so I re-did
it with pydub, only to find that pydub seems to be doing linear fade when crossfading,
resulting in a nasty drop in volume in the middle of the fade.
So does anyone know of a commandline tool or even better python tool, that can cross fade
with equal power or at least lets me do the fade ins/outs with the correct curve, then I
can mix them myself afterwards.
Thanks in advance for any pointers.
NB: I'm not sure my mails are comming through, since I don't see them myself. So
even if you don't have a solution to my problem, a friendly "mail went
through" would be highly appreciated.
Cheers!
--
Atte
http://latestyoutube.a773.dk | http://a773.dk
15 Feb
15 Feb
1:19 a.m.
On Fri, 14 Feb 2020 23:24:37 +0100
Atte <atte(a)youmail.dk> wrote:
Hi
I've written a python script to do crossfades loops in samples. First version was
using commandline tools, but updates of the underlying tools broke my script, so I re-did
it with pydub, only to find that pydub seems to be doing linear fade when crossfading,
resulting in a nasty drop in volume in the middle of the fade.
So does anyone know of a commandline tool or even better python tool, that can cross fade
with equal power or at least lets me do the fade ins/outs with the correct curve, then I
can mix them myself afterwards.
Thanks in advance for any pointers.
NB: I'm not sure my mails are comming through, since I don't see them myself. So
even if you don't have a solution to my problem, a friendly "mail went
through" would be highly appreciated.
Cheers!
This is what I use for near constant power panning. Any good?
float t = (float)(GlobalPar.PPanning - 1) / 126.0f;
pangainL = cosf(t * Pi/2);
pangainR = cosf((1.0f - t) * Pi/2);
Where GlobalPar.PPanning is in the range 0 - 127
It actually gives a 3dB hump in the middle.
--
Will J Godfrey
http://www.musically.me.uk
Say you have a poem and I have a tune.
Exchange them and we can both have a poem, a tune, and a song.
1:59 a.m.
On 2/15/20 12:19 AM, Will Godfrey wrote:
This is what I use for near constant power panning.
Any good?
float t = (float)(GlobalPar.PPanning - 1) / 126.0f;
pangainL = cosf(t * Pi/2);
pangainR = cosf((1.0f - t) * Pi/2);
Why cosine? You might want to use sinus curve as deflection
`t = sin(t * M_PI/2)`, but since signal-power is proportional to the
square of the signal [1], for equal power pan you want square root:
gainL = sqrtf (t) / DB3
gainR = sqrtf (1.f - t) / DB3
where #define DB3 1.4125375 // 10^(3/20)
Where GlobalPar.PPanning is in the range 0 - 127
It actually gives a 3dB hump in the middle
You should attenuate the signal by 3dB to prevent clipping, or maybe
only 2.5dB or perhaps 4.5dB, 4.2dB is also not unheard of:
http://admiralbumblebee.com/music/2019/12/08/Daw-V-Daw-Pan-Curves.html
Cheers!
robin
[1] Power is P = U * I
plug in Ohm's Law: R = U / I
P = U^2 / R
11:25 a.m.
On Sat, 15 Feb 2020 00:59:29 +0100
Robin Gareus <robin(a)gareus.org> wrote:
On 2/15/20 12:19 AM, Will Godfrey wrote:
Most interesting. Thanks for the link. A fascinating read!
I don't actually know where the law I use originally came from, but I'll be
reconsidering.
--
Will J Godfrey
http://www.musically.me.uk
Say you have a poem and I have a tune.
Exchange them and we can both have a poem, a tune, and a song.
This is what I use for near constant power
panning. Any good?
float t = (float)(GlobalPar.PPanning - 1) / 126.0f;
pangainL = cosf(t * Pi/2);
pangainR = cosf((1.0f - t) * Pi/2);
Why cosine? You might want to use sinus curve as deflection
`t = sin(t * M_PI/2)`, but since signal-power is proportional to the
square of the signal [1], for equal power pan you want square root:
gainL = sqrtf (t) / DB3
gainR = sqrtf (1.f - t) / DB3
where #define DB3 1.4125375 // 10^(3/20)
Where GlobalPar.PPanning is in the range 0 - 127
It actually gives a 3dB hump in the middle
You should attenuate the signal by 3dB to prevent clipping, or maybe
only 2.5dB or perhaps 4.5dB, 4.2dB is also not unheard of:
http://admiralbumblebee.com/music/2019/12/08/Daw-V-Daw-Pan-Curves.html
Cheers!
robin
[1] Power is P = U * I
plug in Ohm's Law: R = U / I
P = U^2 / R
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3 comments
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participants (3)
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Atte -
Robin Gareus -
Will Godfrey