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/*
(c)2006 MPlayer / Reynaldo H. Verdejo Pinochet
Based on code by Alex Beregszaszi for his 'center' filter
License: GPL
Simple voice removal filter
*/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "af.h"
// Data for specific instances of this filter
// Initialization and runtime control
static int control(struct af_instance_s* af, int cmd, void* arg)
{
switch(cmd){
case AF_CONTROL_REINIT:
af->data->rate = ((af_data_t*)arg)->rate;
af->data->nch = ((af_data_t*)arg)->nch;
af->data->format= AF_FORMAT_FLOAT_NE;
af->data->bps = 4;
return af_test_output(af,(af_data_t*)arg);
}
return AF_UNKNOWN;
}
// Deallocate memory
static void uninit(struct af_instance_s* af)
{
if(af->data)
free(af->data);
}
// Filter data through filter
static af_data_t* play(struct af_instance_s* af, af_data_t* data)
{
af_data_t* c = data; // Current working data
float* a = c->audio; // Audio data
int len = c->len/4; // Number of samples in current audio block
int nch = c->nch; // Number of channels
register int i;
/*
FIXME1 add a low band pass filter to avoid suppressing
centered bass/drums
FIXME2 better calculated* attenuation factor
*/
for(i=0;i<len;i+=nch)
{
a[i] = (a[i] - a[i+1]) * 0.7;
a[i+1]=a[i];
}
return c;
}
// Allocate memory and set function pointers
static int af_open(af_instance_t* af){
af->control = control;
af->uninit = uninit;
af->play = play;
af->mul.n = 1;
af->mul.d = 1;
af->data = calloc(1,sizeof(af_data_t));
if(af->data == NULL)
return AF_ERROR;
return AF_OK;
}
// Description of this filter
af_info_t af_info_karaoke = {
"Simple karaoke/voice-removal audio filter",
"karaoke",
"Reynaldo H. Verdejo Pinochet",
"",
AF_FLAGS_NOT_REENTRANT,
af_open
};
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