ref: 383093b90ec3abcaf78880255fccb41ad9b78e28
dir: /src/src_linear.c/
/*
** Copyright (C) 2002-2007 Erik de Castro Lopo <erikd@mega-nerd.com>
**
** This program is free software; you can redistribute it and/or modify
** it under the terms of the GNU General Public License as published by
** the Free Software Foundation; either version 2 of the License, or
** (at your option) any later version.
**
** This program is distributed in the hope that it will be useful,
** but WITHOUT ANY WARRANTY; without even the implied warranty of
** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
** GNU General Public License for more details.
**
** You should have received a copy of the GNU General Public License
** along with this program; if not, write to the Free Software
** Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307, USA.
*/
/*
** This code is part of Secret Rabibt Code aka libsamplerate. A commercial
** use license for this code is available, please see:
** http://www.mega-nerd.com/SRC/procedure.html
*/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "config.h"
#include "float_cast.h"
#include "common.h"
static int linear_vari_process (SRC_PRIVATE *psrc, SRC_DATA *data) ;
static void linear_reset (SRC_PRIVATE *psrc) ;
/*========================================================================================
*/
#define LINEAR_MAGIC_MARKER MAKE_MAGIC ('l', 'i', 'n', 'e', 'a', 'r')
#define SRC_DEBUG 0
typedef struct
{ int linear_magic_marker ;
int channels ;
int reset ;
long in_count, in_used ;
long out_count, out_gen ;
float last_value [1] ;
} LINEAR_DATA ;
/*----------------------------------------------------------------------------------------
*/
static int
linear_vari_process (SRC_PRIVATE *psrc, SRC_DATA *data)
{ LINEAR_DATA *linear ;
double src_ratio, input_index, rem ;
int ch ;
if (psrc->private_data == NULL)
return SRC_ERR_NO_PRIVATE ;
linear = (LINEAR_DATA*) psrc->private_data ;
if (linear->reset)
{ /* If we have just been reset, set the last_value data. */
for (ch = 0 ; ch < linear->channels ; ch++)
linear->last_value [ch] = data->data_in [ch] ;
linear->reset = 0 ;
} ;
linear->in_count = data->input_frames * linear->channels ;
linear->out_count = data->output_frames * linear->channels ;
linear->in_used = linear->out_gen = 0 ;
src_ratio = psrc->last_ratio ;
input_index = psrc->last_position ;
/* Calculate samples before first sample in input array. */
while (input_index < 1.0 && linear->out_gen < linear->out_count)
{
if (linear->in_used + linear->channels * input_index > linear->in_count)
break ;
if (linear->out_count > 0 && fabs (psrc->last_ratio - data->src_ratio) > SRC_MIN_RATIO_DIFF)
src_ratio = psrc->last_ratio + linear->out_gen * (data->src_ratio - psrc->last_ratio) / linear->out_count ;
for (ch = 0 ; ch < linear->channels ; ch++)
{ data->data_out [linear->out_gen] = (float) (linear->last_value [ch] + input_index *
(data->data_in [ch] - linear->last_value [ch])) ;
linear->out_gen ++ ;
} ;
/* Figure out the next index. */
input_index += 1.0 / src_ratio ;
} ;
rem = fmod_one (input_index) ;
linear->in_used += linear->channels * lrint (input_index - rem) ;
input_index = rem ;
/* Main processing loop. */
while (linear->out_gen < linear->out_count && linear->in_used + linear->channels * input_index <= linear->in_count)
{
if (linear->out_count > 0 && fabs (psrc->last_ratio - data->src_ratio) > SRC_MIN_RATIO_DIFF)
src_ratio = psrc->last_ratio + linear->out_gen * (data->src_ratio - psrc->last_ratio) / linear->out_count ;
if (SRC_DEBUG && linear->in_used < linear->channels && input_index < 1.0)
{ printf ("Whoops!!!! in_used : %ld channels : %d input_index : %f\n", linear->in_used, linear->channels, input_index) ;
exit (1) ;
} ;
for (ch = 0 ; ch < linear->channels ; ch++)
{ data->data_out [linear->out_gen] = (float) (data->data_in [linear->in_used - linear->channels + ch] + input_index *
(data->data_in [linear->in_used + ch] - data->data_in [linear->in_used - linear->channels + ch])) ;
linear->out_gen ++ ;
} ;
/* Figure out the next index. */
input_index += 1.0 / src_ratio ;
rem = fmod_one (input_index) ;
linear->in_used += linear->channels * lrint (input_index - rem) ;
input_index = rem ;
} ;
if (linear->in_used > linear->in_count)
{ input_index += (linear->in_used - linear->in_count) / linear->channels ;
linear->in_used = linear->in_count ;
} ;
psrc->last_position = input_index ;
if (linear->in_used > 0)
for (ch = 0 ; ch < linear->channels ; ch++)
linear->last_value [ch] = data->data_in [linear->in_used - linear->channels + ch] ;
/* Save current ratio rather then target ratio. */
psrc->last_ratio = src_ratio ;
data->input_frames_used = linear->in_used / linear->channels ;
data->output_frames_gen = linear->out_gen / linear->channels ;
return SRC_ERR_NO_ERROR ;
} /* linear_vari_process */
/*------------------------------------------------------------------------------
*/
const char*
linear_get_name (int src_enum)
{
if (src_enum == SRC_LINEAR)
return "Linear Interpolator" ;
return NULL ;
} /* linear_get_name */
const char*
linear_get_description (int src_enum)
{
if (src_enum == SRC_LINEAR)
return "Linear interpolator, very fast, poor quality." ;
return NULL ;
} /* linear_get_descrition */
int
linear_set_converter (SRC_PRIVATE *psrc, int src_enum)
{ LINEAR_DATA *linear = NULL ;
if (src_enum != SRC_LINEAR)
return SRC_ERR_BAD_CONVERTER ;
if (psrc->private_data != NULL)
{ linear = (LINEAR_DATA*) psrc->private_data ;
if (linear->linear_magic_marker != LINEAR_MAGIC_MARKER)
{ free (psrc->private_data) ;
psrc->private_data = NULL ;
} ;
} ;
if (psrc->private_data == NULL)
{ linear = calloc (1, sizeof (*linear) + psrc->channels * sizeof (float)) ;
if (linear == NULL)
return SRC_ERR_MALLOC_FAILED ;
psrc->private_data = linear ;
} ;
linear->linear_magic_marker = LINEAR_MAGIC_MARKER ;
linear->channels = psrc->channels ;
psrc->const_process = linear_vari_process ;
psrc->vari_process = linear_vari_process ;
psrc->reset = linear_reset ;
linear_reset (psrc) ;
return SRC_ERR_NO_ERROR ;
} /* linear_set_converter */
/*===================================================================================
*/
static void
linear_reset (SRC_PRIVATE *psrc)
{ LINEAR_DATA *linear = NULL ;
linear = (LINEAR_DATA*) psrc->private_data ;
if (linear == NULL)
return ;
linear->channels = psrc->channels ;
linear->reset = 1 ;
memset (linear->last_value, 0, sizeof (linear->last_value [0]) * linear->channels) ;
} /* linear_reset */