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/* This audio filter delays the output signal for the different
channels and can be used for simple position panning. Extension for
this filter would be a reverb.
*/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <inttypes.h>
#include "af.h"
#define L 65536
#define UPDATEQI(qi) qi=(qi+1)&(L-1)
// Data for specific instances of this filter
typedef struct af_delay_s
{
void* q[AF_NCH]; // Circular queues used for delaying audio signal
int wi[AF_NCH]; // Write index
int ri; // Read index
float d[AF_NCH]; // Delay [ms]
}af_delay_t;
// Initialization and runtime control
static int control(struct af_instance_s* af, int cmd, void* arg)
{
af_delay_t* s = af->setup;
switch(cmd){
case AF_CONTROL_REINIT:{
int i;
// Free prevous delay queues
for(i=0;i<af->data->nch;i++){
if(s->q[i])
free(s->q[i]);
}
af->data->rate = ((af_data_t*)arg)->rate;
af->data->nch = ((af_data_t*)arg)->nch;
af->data->format = ((af_data_t*)arg)->format;
af->data->bps = ((af_data_t*)arg)->bps;
// Allocate new delay queues
for(i=0;i<af->data->nch;i++){
s->q[i] = calloc(L,af->data->bps);
if(NULL == s->q[i])
af_msg(AF_MSG_FATAL,"[delay] Out of memory\n");
}
return control(af,AF_CONTROL_DELAY_LEN | AF_CONTROL_SET,s->d);
}
case AF_CONTROL_COMMAND_LINE:{
int n = 1;
int i = 0;
char* cl = arg;
while(n && i < AF_NCH ){
sscanf(cl,"%f:%n",&s->d[i],&n);
if(n==0 || cl[n-1] == '\0')
break;
cl=&cl[n];
i++;
}
return AF_OK;
}
case AF_CONTROL_DELAY_LEN | AF_CONTROL_SET:{
int i;
if(AF_OK != af_from_ms(AF_NCH, arg, s->wi, af->data->rate, 0.0, 1000.0))
return AF_ERROR;
s->ri = 0;
for(i=0;i<AF_NCH;i++){
af_msg(AF_MSG_DEBUG0,"[delay] Channel %i delayed by %0.3fms\n",
i,clamp(s->d[i],0.0,1000.0));
af_msg(AF_MSG_DEBUG1,"[delay] Channel %i delayed by %i samples\n",
i,s->wi[i]);
}
return AF_OK;
}
case AF_CONTROL_DELAY_LEN | AF_CONTROL_GET:{
int i;
for(i=0;i<AF_NCH;i++){
if(s->ri > s->wi[i])
s->wi[i] = L - (s->ri - s->wi[i]);
else
s->wi[i] = s->wi[i] - s->ri;
}
return af_to_ms(AF_NCH, s->wi, arg, af->data->rate);
}
}
return AF_UNKNOWN;
}
// Deallocate memory
static void uninit(struct af_instance_s* af)
{
int i;
if(af->data)
free(af->data);
for(i=0;i<AF_NCH;i++)
if(((af_delay_t*)(af->setup))->q[i])
free(((af_delay_t*)(af->setup))->q[i]);
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_delay_t* s = af->setup; // Setup for this instance
int nch = c->nch; // Number of channels
int len = c->len/c->bps; // Number of sample in data chunk
int ri = 0;
int ch,i;
for(ch=0;ch<nch;ch++){
switch(c->bps){
case 1:{
int8_t* a = c->audio;
int8_t* q = s->q[ch];
int wi = s->wi[ch];
ri = s->ri;
for(i=ch;i<len;i+=nch){
q[wi] = a[i];
a[i] = q[ri];
UPDATEQI(wi);
UPDATEQI(ri);
}
s->wi[ch] = wi;
break;
}
case 2:{
int16_t* a = c->audio;
int16_t* q = s->q[ch];
int wi = s->wi[ch];
ri = s->ri;
for(i=ch;i<len;i+=nch){
q[wi] = a[i];
a[i] = q[ri];
UPDATEQI(wi);
UPDATEQI(ri);
}
s->wi[ch] = wi;
break;
}
case 4:{
int32_t* a = c->audio;
int32_t* q = s->q[ch];
int wi = s->wi[ch];
ri = s->ri;
for(i=ch;i<len;i+=nch){
q[wi] = a[i];
a[i] = q[ri];
UPDATEQI(wi);
UPDATEQI(ri);
}
s->wi[ch] = wi;
break;
}
}
}
s->ri = ri;
return c;
}
// Allocate memory and set function pointers
static int 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));
af->setup=calloc(1,sizeof(af_delay_t));
if(af->data == NULL || af->setup == NULL)
return AF_ERROR;
return AF_OK;
}
// Description of this filter
af_info_t af_info_delay = {
"Delay audio filter",
"delay",
"Anders",
"",
AF_FLAGS_REENTRANT,
open
};
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