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/* Extrastereo effect plugin
* (linearly increases difference between L&R channels)
*
* Current limitations:
* - only AFMT_S16_LE is supported currently
*
* License: GPLv2 (as a mix of pl_volume.c and
* xmms:stereo_plugin/stereo.c)
*
* Author: pl <p_l@gmx.fr> (c) 2002 and beyond...
* */
#define PLUGIN
#include <stdio.h>
#include <stdlib.h>
#include <inttypes.h>
#include "audio_out.h"
#include "audio_plugin.h"
#include "audio_plugin_internal.h"
#include "afmt.h"
static ao_info_t info = {
"Extra stereo plugin",
"extrastereo",
"pl <p_l@gmx.fr>",
""
};
LIBAO_PLUGIN_EXTERN(extrastereo)
// local data
static struct {
float mul; // intensity
int inuse; // This plugin is in use TRUE, FALSE
int format; // sample format
} pl_extrastereo = {2.5, 0, 0};
// to set/get/query special features/parameters
static int control(int cmd,int arg){
switch(cmd){
case AOCONTROL_PLUGIN_SET_LEN:
return CONTROL_OK;
}
return CONTROL_UNKNOWN;
}
// open & setup audio device
// return: 1=success 0=fail
static int init(){
switch(ao_plugin_data.format){
case(AFMT_S16_LE):
break;
default:
fprintf(stderr,"[pl_extrastereo] Audio format not yet suported \n");
return 0;
}
pl_extrastereo.mul=ao_plugin_cfg.pl_extrastereo_mul;
pl_extrastereo.format=ao_plugin_data.format;
pl_extrastereo.inuse=1;
printf("[pl_extrastereo] Extra stereo plugin in use (multiplier=%2.2f).\n",
pl_extrastereo.mul);
return 1;
}
// close plugin
static void uninit(){
pl_extrastereo.inuse=0;
}
// empty buffers
static void reset(){
}
// processes 'ao_plugin_data.len' bytes of 'data'
// called for every block of data
static int play(){
switch(pl_extrastereo.format){
case(AFMT_S16_LE): {
int16_t* data=(int16_t*)ao_plugin_data.data;
int len=ao_plugin_data.len / 2; // 16 bits samples
float mul = pl_extrastereo.mul;
int32_t i, avg, ltmp, rtmp;
for (i=0; i < len ; i += 2) {
avg = (data[i] + data[i + 1]) / 2;
ltmp = avg + (int) (mul * (data[i] - avg));
rtmp = avg + (int) (mul * (data[i + 1] - avg));
if (ltmp < -32768) {
ltmp = -32768;
} else if (ltmp > 32767) {
ltmp = 32767;
}
if (rtmp < -32768) {
rtmp = -32768;
} else if (rtmp > 32767) {
rtmp = 32767;
}
data[i] = ltmp;
data[i + 1] = rtmp;
}
break;
}
default:
return 0;
}
return 1;
}
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