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/*=============================================================================
//
// This software has been released under the terms of the GNU General Public
// license. See http://www.gnu.org/copyleft/gpl.html for details.
//
// Copyright 2004 Alex Beregszaszi & Pierre Lombard
//
//=============================================================================
*/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <inttypes.h>
#include <math.h>
#include <limits.h>
#include "af.h"
// Data for specific instances of this filter
typedef struct af_extrastereo_s
{
float mul;
}af_extrastereo_t;
static af_data_t* play_s16(struct af_instance_s* af, af_data_t* data);
static af_data_t* play_float(struct af_instance_s* af, af_data_t* data);
// Initialization and runtime control
static int control(struct af_instance_s* af, int cmd, void* arg)
{
af_extrastereo_t* s = (af_extrastereo_t*)af->setup;
switch(cmd){
case AF_CONTROL_REINIT:{
// Sanity check
if(!arg) return AF_ERROR;
af->data->rate = ((af_data_t*)arg)->rate;
af->data->nch = 2;
if (((af_data_t*)arg)->format == AF_FORMAT_FLOAT_NE)
{
af->data->format = AF_FORMAT_FLOAT_NE;
af->data->bps = 4;
af->play = play_float;
}// else
{
af->data->format = AF_FORMAT_S16_NE;
af->data->bps = 2;
af->play = play_s16;
}
return af_test_output(af,(af_data_t*)arg);
}
case AF_CONTROL_COMMAND_LINE:{
float f;
sscanf((char*)arg,"%f", &f);
s->mul = f;
return AF_OK;
}
case AF_CONTROL_ES_MUL | AF_CONTROL_SET:
s->mul = *(float*)arg;
return AF_OK;
case AF_CONTROL_ES_MUL | AF_CONTROL_GET:
*(float*)arg = s->mul;
return AF_OK;
}
return AF_UNKNOWN;
}
// Deallocate memory
static void uninit(struct af_instance_s* af)
{
if(af->data)
free(af->data);
if(af->setup)
free(af->setup);
}
// Filter data through filter
static af_data_t* play_s16(struct af_instance_s* af, af_data_t* data)
{
af_extrastereo_t *s = af->setup;
register int i = 0;
int16_t *a = (int16_t*)data->audio; // Audio data
int len = data->len/2; // Number of samples
int avg, l, r;
for (i = 0; i < len; i+=2)
{
avg = (a[i] + a[i + 1]) / 2;
l = avg + (int)(s->mul * (a[i] - avg));
r = avg + (int)(s->mul * (a[i + 1] - avg));
a[i] = clamp(l, SHRT_MIN, SHRT_MAX);
a[i + 1] = clamp(r, SHRT_MIN, SHRT_MAX);
}
return data;
}
static af_data_t* play_float(struct af_instance_s* af, af_data_t* data)
{
af_extrastereo_t *s = af->setup;
register int i = 0;
float *a = (float*)data->audio; // Audio data
int len = data->len/4; // Number of samples
float avg, l, r;
for (i = 0; i < len; i+=2)
{
avg = (a[i] + a[i + 1]) / 2;
l = avg + (s->mul * (a[i] - avg));
r = avg + (s->mul * (a[i + 1] - avg));
a[i] = af_softclip(l);
a[i + 1] = af_softclip(r);
}
return data;
}
// Allocate memory and set function pointers
static int af_open(af_instance_t* af){
af->control=control;
af->uninit=uninit;
af->play=play_s16;
af->mul=1;
af->data=calloc(1,sizeof(af_data_t));
af->setup=calloc(1,sizeof(af_extrastereo_t));
if(af->data == NULL || af->setup == NULL)
return AF_ERROR;
((af_extrastereo_t*)af->setup)->mul = 2.5;
return AF_OK;
}
// Description of this filter
af_info_t af_info_extrastereo = {
"Extra stereo",
"extrastereo",
"Alex Beregszaszi & Pierre Lombard",
"",
AF_FLAGS_NOT_REENTRANT,
af_open
};
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