#math - Sun 1 Apr 2007 between 00:40 and 00:55

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TRWBWJabberWalkie: but its seperable, so you can write it as applying 1D convulution twice, once in x, once in y
JabberWalkieTRWBW: can i still have the relation F[ f*g]= F[f] F[g], with a 2 dimentional fourier transform?
TRWBWJabberWalkie: yes
holst"Life is good" :P
JabberWalkiesweet..
holstits a bit ironic
we think of theorems as gifts of the gods
JabberWalkiewe do?
holstbut actually they are just a product of the axioms we setup to begin with
^Manuhey people
i'm trying to understand this magic 'decibel' curve..
i am writing some software which sets the audio level in decibels... but i want the volume to behave as a linear quantity..
but i cant work out the decibel graph, which i need to understand so i can negate it into a linear graph.
ie, 0.5 volume should be half as loud, not damn near silent as it is given half the decibel range.
holstthe graph is monotonic right?
^Manuin what sense?
holstthat means for any y=f(x) on the curve you can find g(y)=x. solve for x
^Manuthis is amplitude, not frequency.
i have no idea.
i just know i set the level in decibels.. but i dont really understand what a decibel is..
its used in so many different fields..
holstbut what are you saying
^Manuits obviously graphable, its some sort of curve.
well see the amplitude is set by some function of the level value in decibels...
but i dont know that function :/
i just want to set the amplitude to my value directly.. but directsound doesnt provide any interface for that..
so i need to calculate the correct level, in decibels to get what i want.. which i dont know how to do.
holstyou insert something in [0,1] range to the directsound api?
1 = maximum vol; 0 = silent
JabberWalkie^Manu: somthing at 60db is 10 times louder that 50db.....
^Manuno, i insert something in [DSBVOLUME_MIN, DSBVOLUME_MAX] range to dsound./
JabberWalkie70db would be 100 times louder than 50db
etc..
^Manuso if i have v in [0, 1]... and i use (DSBVOLUME_MAX - DSBVOLUME_MIN) * v..
i get a totally non-linear volume control ;)
which is obvious, but i dont know how to solve it.
holstdecibel is related to what the human ear think is "loudness" http://www.phys.unsw.edu.au/jw/dB.html#log
^Manui realise that.. i understand its concept.. but i dont understand it mathematically...
holst^Manu: most probably the volumne in the api isnt dB
^Manuso i cant effectively cancel it out.. because really i just want to address the amplitude coming out my speakers directly without dsound messing with it..

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