audacity/src/effects/TimeWarper.cpp

/**********************************************************************

   Audacity - A Digital Audio Editor
   Copyright 1999-2009 Audacity Team
   License: GPL v2 - see LICENSE.txt

   Dan Horgan

******************************************************************//**

\file TimeWarper.cpp
\brief Contains definitions for IdentityTimeWarper, ShiftTimeWarper,
LinearTimeWarper, LogarithmicTimeWarper, QuadraticTimeWarper,
Geometric TimeWarper classes

*//*******************************************************************/

#include "../Audacity.h"
#include "TimeWarper.h"

#include <wx/string.h>
#include <math.h>

double IdentityTimeWarper::Warp(double originalTime) const
{
   return originalTime;
}

double ShiftTimeWarper::Warp(double originalTime) const
{
   return mWarper->Warp(originalTime + mShift);
}

double LinearTimeWarper::Warp(double originalTime) const
{
   return originalTime*mScale + mShift;
}

double LinearInputRateTimeWarper::Warp(double originalTime) const
{
   double rate = mRateWarper.Warp(originalTime);
   return mTStart + mScale*log(rate/mRStart);
}

LinearInputRateTimeWarper::LinearInputRateTimeWarper(double tStart, double tEnd,
                                                     double rStart, double rEnd)
: mRateWarper(tStart, rStart, tEnd, rEnd), mRStart(rStart),
  mTStart(tStart), mScale((tEnd-tStart)/(rEnd-rStart))
{
   wxASSERT(mRStart != 0.0);
   wxASSERT(tStart < tEnd);
}

double LinearOutputRateTimeWarper::Warp(double originalTime) const
{
   double scaledTime = mTimeWarper.Warp(originalTime);
   return mTStart + mScale*(sqrt(mC1 + scaledTime * mC2) - mRStart);
}

LinearOutputRateTimeWarper::LinearOutputRateTimeWarper(double tStart, double tEnd,
                                                       double rStart, double rEnd)
: mTimeWarper(tStart, 0.0, tEnd, 1.0),
  mRStart(rStart), mTStart(tStart),
  mScale(2.0*(tEnd-tStart)/(rEnd*rEnd-rStart*rStart)),
  mC1(rStart*rStart), mC2(rEnd*rEnd-rStart*rStart)
{
   wxASSERT(rStart != rEnd);
   wxASSERT(rStart > 0.0);
   wxASSERT(rEnd > 0.0);
   wxASSERT(tStart < tEnd);
}

double LinearInputStretchTimeWarper::Warp(double originalTime) const
{
   double scaledTime = mTimeWarper.Warp(originalTime);
   return mTStart + mC1 * scaledTime * (1.0 + mC2 * scaledTime);
}

LinearInputStretchTimeWarper::LinearInputStretchTimeWarper(double tStart, double tEnd,
                                                           double rStart, double rEnd)
: mTimeWarper(tStart, 0.0, tEnd, 1.0), mTStart(tStart),
  mC1((tEnd-tStart)/rStart), mC2(0.5*(rStart/rEnd - 1.0))
{
   wxASSERT(rStart > 0.0);
   wxASSERT(rEnd > 0.0);
   wxASSERT(tStart < tEnd);
}

double LinearOutputStretchTimeWarper::Warp(double originalTime) const
{
   double scaledTime = mTimeWarper.Warp(originalTime);
   return mTStart + mC1 * (pow(mC2, scaledTime) - 1.0);
}

LinearOutputStretchTimeWarper::LinearOutputStretchTimeWarper(double tStart, double tEnd,
                                                             double rStart, double rEnd)
: mTimeWarper(tStart, 0.0, tEnd, 1.0), mTStart(tStart),
  mC1((tEnd-tStart)/(rStart*log(rStart/rEnd))), mC2(rStart/rEnd)
{
   wxASSERT(rStart != rEnd);
   wxASSERT(rStart > 0.0);
   wxASSERT(rEnd > 0.0);
   wxASSERT(tStart < tEnd);
}

double GeometricInputTimeWarper::Warp(double originalTime) const
{
   double scaledTime = mTimeWarper.Warp(originalTime);
   return mTStart + mScale*(pow(mRatio,scaledTime) - 1.0);
}

GeometricInputTimeWarper::GeometricInputTimeWarper(double tStart, double tEnd,
                                                   double rStart, double rEnd)
: mTimeWarper(tStart, 0.0, tEnd, 1.0), mTStart(tStart),
  mScale((tEnd-tStart)/(log(rStart/rEnd)*rStart)), mRatio(rStart/rEnd)
{
   wxASSERT(rStart != rEnd);
   wxASSERT(rStart > 0.0);
   wxASSERT(rEnd > 0.0);
   wxASSERT(tStart < tEnd);
}

double GeometricOutputTimeWarper::Warp(double originalTime) const
{
   double scaledTime = mTimeWarper.Warp(originalTime);
   return mTStart + mScale*log1p(mC0 * scaledTime);
}

GeometricOutputTimeWarper::GeometricOutputTimeWarper(double tStart, double tEnd,
                                                     double rStart, double rEnd)
: mTimeWarper(tStart, 0.0, tEnd, 1.0), mTStart(tStart),
  mScale((tEnd-tStart)/(rEnd-rStart)), mC0((rEnd-rStart)/rStart)
{
   wxASSERT(rStart > 0.0);
   wxASSERT(rEnd > 0.0);
   wxASSERT(tStart < tEnd);
}

StepTimeWarper::StepTimeWarper(double tStep, double offset)
: mTStep(tStep), mOffset(offset)
{ }

double StepTimeWarper::Warp(double originalTime) const
{
   return originalTime + ((originalTime > mTStep) ? mOffset : 0.0);
}