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delta.cc
/*************************************************************************/
/* */
/* Centre for Speech Technology Research */
/* University of Edinburgh, UK */
/* Copyright (c) 1995,1996 */
/* All Rights Reserved. */
/* */
/* Permission is hereby granted, free of charge, to use and distribute */
/* this software and its documentation without restriction, including */
/* without limitation the rights to use, copy, modify, merge, publish, */
/* distribute, sublicense, and/or sell copies of this work, and to */
/* permit persons to whom this work is furnished to do so, subject to */
/* the following conditions: */
/* 1. The code must retain the above copyright notice, this list of */
/* conditions and the following disclaimer. */
/* 2. Any modifications must be clearly marked as such. */
/* 3. Original authors' names are not deleted. */
/* 4. The authors' names are not used to endorse or promote products */
/* derived from this software without specific prior written */
/* permission. */
/* */
/* THE UNIVERSITY OF EDINBURGH AND THE CONTRIBUTORS TO THIS WORK */
/* DISCLAIM ALL WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING */
/* ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO EVENT */
/* SHALL THE UNIVERSITY OF EDINBURGH NOR THE CONTRIBUTORS BE LIABLE */
/* FOR ANY SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES */
/* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN */
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/* ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF */
/* THIS SOFTWARE. */
/* */
/*************************************************************************/
/* Author : Simon King */
/* Date : July 1995 */
/*-----------------------------------------------------------------------*/
/* Compute delta coefficients for */
/* Tracks and Tracks */
/* */
/*=======================================================================*/
#include <cstdlib>
#include "EST_Track.h"
#include "EST_Wave.h"
# define MAX_DELTA_ORDER 2
/// max. number of points on which the delta co-eff is based
# define MAX_REGRESSION_LENGTH 4
static float compute_gradient(const EST_FVector &x, int num_points);
void delta(EST_Track &tr, EST_Track &d, int regression_length)
{
int reg_index, this_index;
// need at least two points to compute gradient
if ((regression_length < 2)||(regression_length > MAX_REGRESSION_LENGTH)){
cerr << "delta(EST_Track&, int) : ERROR : regression_length is "
<< regression_length << endl;
exit(0);
}
// temp stores the points passed to compute_gradient
EST_FVector temp(regression_length);
for (int j = 0; j < tr.num_channels(); j++ )
for (int i = 0; i < tr.num_frames(); i++)
{
// copy values needed to compute gradient into temp[]
for (reg_index=0; reg_index<regression_length; reg_index++)
{
// gradient is computed from points to left of current time
// rather than points centred around the current time
this_index = i - reg_index;
if (this_index >= 0)
temp[reg_index] = tr.a(this_index, j);
}
// gradient at frame 0 is defined as 0
if (i < 1)
d.a(i, j) = 0.0;
else if (i < regression_length - 1)
// enough data, but would prefer more
// number of points available is only i+1
d.a(i, j) = compute_gradient(temp, i + 1);
else
// plenty of data, use the last regression_length points
d.a(i, j) = compute_gradient(temp, regression_length);
}
}
void delta(EST_Wave &tr, EST_Wave &d, int regression_length)
{
int reg_index, this_index;
// need at least two points to compute gradient
if ((regression_length < 2)||(regression_length > MAX_REGRESSION_LENGTH)){
cerr << "delta(EST_Track&, int) : ERROR : regression_length is "
<< regression_length << endl;
exit(0);
}
// temp stores the points passed to compute_gradient
EST_FVector temp(regression_length);
for (int j = 0; j < tr.num_channels(); j++ )
for (int i = 0; i < tr.num_samples(); i++)
{
// copy values needed to compute gradient into temp[]
for (reg_index=0; reg_index<regression_length; reg_index++)
{
// gradient is computed from points to left of current time
// rather than points centred around the current time
this_index = i - reg_index;
if (this_index >= 0)
temp.a_no_check(reg_index) = (float)tr.a(this_index, j);
}
// gradient at frame 0 is defined as 0
if (i < 1)
d.a(i, j) = 0;
else if (i < regression_length - 1)
// enough data, but would prefer more
// number of points available is only i+1
d.a(i, j) = (short)compute_gradient(temp, i + 1);
else
// plenty of data, use the last regression_length points
d.a(i, j) = (short)compute_gradient(temp, regression_length);
}
}
static float compute_gradient(const EST_FVector &x, int num_points)
{
float gradient;
// NB x[0] is the point LATEST in time
// so x[1] is really x[t-1]
// time between points is assumed to be one unit
// These are solutions to least-squares fit of straight line
// to num_points points.
switch (num_points){
case 1:
gradient = 0.0;
break;
case 2:
gradient = x(0) - x(1);
break;
case 3:
gradient = (x(0) -x(2)) / 2.0;
break;
case 4:
gradient = ( (3.0*x(0)) + x(1) - x(2) - (3.0 * x(3)) ) / 10.0;
break;
default:
cerr << "compute_gradient(float*, int) : ERROR : num_points is"
<< num_points << endl;
exit(0);
break;
}
return gradient;
}
EST_FVector
Definition EST_FMatrix.h:114
EST_Track
Definition EST_Track.h:89
EST_Track::a
float & a(int i, int c=0)
Definition EST_Track.cc:1022
EST_Track::num_channels
int num_channels() const
return number of channels in track
Definition EST_Track.h:656
EST_Track::num_frames
int num_frames() const
return number of frames in track
Definition EST_Track.h:650
EST_Wave
Definition EST_Wave.h:65
EST_Wave::a
short & a(int i, int channel=0)
Definition EST_Wave.cc:128
EST_Wave::num_channels
int num_channels() const
return the number of channels in the waveform
Definition EST_Wave.h:145
EST_Wave::num_samples
int num_samples() const
return the number of samples in the waveform
Definition EST_Wave.h:143