mirror of https://github.com/mpv-player/mpv
118 lines
2.9 KiB
C
118 lines
2.9 KiB
C
/*
|
|
(C) Alex Beregszaszi
|
|
License: GPL
|
|
|
|
This filter adds a center channel to the audio stream by
|
|
averaging the left and right channel.
|
|
There are two runtime controls one for setting which channel to
|
|
insert the center-audio into called AF_CONTROL_SUB_CH.
|
|
|
|
FIXME: implement a high-pass filter for better results.
|
|
*/
|
|
|
|
#include <stdio.h>
|
|
#include <stdlib.h>
|
|
#include <string.h>
|
|
|
|
#include "af.h"
|
|
|
|
// Data for specific instances of this filter
|
|
typedef struct af_center_s
|
|
{
|
|
int ch; // Channel number which to insert the filtered data
|
|
}af_center_t;
|
|
|
|
// Initialization and runtime control
|
|
static int control(struct af_instance_s* af, int cmd, void* arg)
|
|
{
|
|
af_center_t* s = 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 = max(s->ch+1,((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);
|
|
}
|
|
case AF_CONTROL_COMMAND_LINE:{
|
|
int ch=1;
|
|
sscanf(arg,"%i", &ch);
|
|
return control(af,AF_CONTROL_CENTER_CH | AF_CONTROL_SET, &ch);
|
|
}
|
|
case AF_CONTROL_CENTER_CH | AF_CONTROL_SET: // Requires reinit
|
|
// Sanity check
|
|
if((*(int*)arg >= AF_NCH) || (*(int*)arg < 0)){
|
|
af_msg(AF_MSG_ERROR,"[sub] Center channel number must be between "
|
|
" 0 and %i current value is %i\n", AF_NCH-1, *(int*)arg);
|
|
return AF_ERROR;
|
|
}
|
|
s->ch = *(int*)arg;
|
|
return AF_OK;
|
|
case AF_CONTROL_CENTER_CH | AF_CONTROL_GET:
|
|
*(int*)arg = s->ch;
|
|
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(struct af_instance_s* af, af_data_t* data)
|
|
{
|
|
af_data_t* c = data; // Current working data
|
|
af_center_t* s = af->setup; // Setup for this instance
|
|
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
|
|
int ch = s->ch; // Channel in which to insert the center audio
|
|
register int i;
|
|
|
|
// Run filter
|
|
for(i=0;i<len;i+=nch){
|
|
// Average left and right
|
|
a[i+ch] = (a[i]/2) + (a[i+1]/2);
|
|
}
|
|
|
|
return c;
|
|
}
|
|
|
|
// Allocate memory and set function pointers
|
|
static int open(af_instance_t* af){
|
|
af_center_t* s;
|
|
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));
|
|
af->setup=s=calloc(1,sizeof(af_center_t));
|
|
if(af->data == NULL || af->setup == NULL)
|
|
return AF_ERROR;
|
|
// Set default values
|
|
s->ch = 1; // Channel nr 2
|
|
return AF_OK;
|
|
}
|
|
|
|
// Description of this filter
|
|
af_info_t af_info_center = {
|
|
"Audio filter for adding a center channel",
|
|
"center",
|
|
"Alex Beregszaszi",
|
|
"",
|
|
AF_FLAGS_NOT_REENTRANT,
|
|
open
|
|
};
|