cog/Audio/Helper.m

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/*
* Helper.c
* CogAudio
*
* Created by Andre Reffhaug on 2/17/08.
* Copyright 2008 __MyCompanyName__. All rights reserved.
*
*/
#include <math.h>
#include "Helper.h"
//These functions are helpers for the process of converting volume from a linear to logarithmic scale.
//Numbers that goes in to audioPlayer should be logarithmic. Numbers that are displayed to the user should be linear.
//Here's why: http://www.dr-lex.34sp.com/info-stuff/volumecontrols.html
//We are using the approximation of X^4.
//Input/Output values are in percents.
double logarithmicToLinear(double logarithmic)
{
return pow((logarithmic/MAX_VOLUME), 0.25) * 100.0;
}
double linearToLogarithmic(double linear)
{
return (linear/100) * (linear/100) * (linear/100) * (linear/100) * MAX_VOLUME;
}
//End helper volume function thingies. ONWARDS TO GLORY!