libaf/af_delay.c

   1 /* This audio filter delays the output signal for the different
   2    channels and can be used for simple position panning. Extension for
   3    this filter would be a reverb.
   4 */
   5 #include <stdio.h>
   6 #include <stdlib.h>
   7 #include <string.h>
   8 #include <inttypes.h>
   9
  10 #include "af.h"
  11
  12 #define L 65536
  13
  14 #define UPDATEQI(qi) qi=(qi+1)&(L-1)
  15
  16 // Data for specific instances of this filter
  17 typedef struct af_delay_s
  18 {
  19   void* q[AF_NCH];      // Circular queues used for delaying audio signal
  20   int   wi[AF_NCH];     // Write index
  21   int   ri;             // Read index
  22   float d[AF_NCH];      // Delay [ms]
  23 }af_delay_t;
  24
  25 // Initialization and runtime control
  26 static int control(struct af_instance_s* af, int cmd, void* arg)
  27 {
  28   af_delay_t* s = af->setup;
  29   switch(cmd){
  30   case AF_CONTROL_REINIT:{
  31     int i;
  32
  33     // Free prevous delay queues
  34     for(i=0;i<af->data->nch;i++){
  35       if(s->q[i])
  36         free(s->q[i]);
  37     }
  38
  39     af->data->rate   = ((af_data_t*)arg)->rate;
  40     af->data->nch    = ((af_data_t*)arg)->nch;
  41     af->data->format = ((af_data_t*)arg)->format;
  42     af->data->bps    = ((af_data_t*)arg)->bps;
  43
  44     // Allocate new delay queues
  45     for(i=0;i<af->data->nch;i++){
  46       s->q[i] = calloc(L,af->data->bps);
  47       if(NULL == s->q[i])
  48         af_msg(AF_MSG_FATAL,"[delay] Out of memory\n");
  49     }
  50
  51     return control(af,AF_CONTROL_DELAY_LEN | AF_CONTROL_SET,s->d);
  52   }
  53   case AF_CONTROL_COMMAND_LINE:{
  54     int n = 1;
  55     int i = 0;
  56     char* cl = arg;
  57     while(n && i < AF_NCH ){
  58       sscanf(cl,"%f:%n",&s->d[i],&n);
  59       if(n==0 || cl[n-1] == '\0')
  60         break;
  61       cl=&cl[n];
  62       i++;
  63     }
  64     return AF_OK;
  65   }
  66   case AF_CONTROL_DELAY_LEN | AF_CONTROL_SET:{
  67     int i;
  68     if(AF_OK != af_from_ms(AF_NCH, arg, s->wi, af->data->rate, 0.0, 1000.0))
  69       return AF_ERROR;
  70     s->ri = 0;
  71     for(i=0;i<AF_NCH;i++){
  72       af_msg(AF_MSG_DEBUG0,"[delay] Channel %i delayed by %0.3fms\n",
  73              i,clamp(s->d[i],0.0,1000.0));
  74       af_msg(AF_MSG_DEBUG1,"[delay] Channel %i delayed by %i samples\n",
  75              i,s->wi[i]);
  76     }
  77     return AF_OK;
  78   }
  79   case AF_CONTROL_DELAY_LEN | AF_CONTROL_GET:{
  80     int i;
  81     for(i=0;i<AF_NCH;i++){
  82       if(s->ri > s->wi[i])
  83         s->wi[i] = L - (s->ri - s->wi[i]);
  84       else
  85         s->wi[i] = s->wi[i] - s->ri;
  86     }
  87     return af_to_ms(AF_NCH, s->wi, arg, af->data->rate);
  88   }
  89   }
  90   return AF_UNKNOWN;
  91 }
  92
  93 // Deallocate memory
  94 static void uninit(struct af_instance_s* af)
  95 {
  96   int i;
  97   if(af->data)
  98     free(af->data);
  99   for(i=0;i<AF_NCH;i++)
 100     if(((af_delay_t*)(af->setup))->q[i])
 101       free(((af_delay_t*)(af->setup))->q[i]);
 102   if(af->setup)
 103     free(af->setup);
 104 }
 105
 106 // Filter data through filter
 107 static af_data_t* play(struct af_instance_s* af, af_data_t* data)
 108 {
 109   af_data_t*    c   = data;      // Current working data
 110   af_delay_t*   s   = af->setup; // Setup for this instance
 111   int           nch = c->nch;    // Number of channels
 112   int           len = c->len/c->bps; // Number of sample in data chunk
 113   int           ri  = 0;
 114   int           ch,i;
 115   for(ch=0;ch<nch;ch++){
 116     switch(c->bps){
 117     case 1:{
 118       int8_t* a = c->audio;
 119       int8_t* q = s->q[ch];
 120       int wi = s->wi[ch];
 121       ri = s->ri;
 122       for(i=ch;i<len;i+=nch){
 123         q[wi] = a[i];
 124         a[i]  = q[ri];
 125         UPDATEQI(wi);
 126         UPDATEQI(ri);
 127       }
 128       s->wi[ch] = wi;
 129       break;
 130     }
 131     case 2:{
 132       int16_t* a = c->audio;
 133       int16_t* q = s->q[ch];
 134       int wi = s->wi[ch];
 135       ri = s->ri;
 136       for(i=ch;i<len;i+=nch){
 137         q[wi] = a[i];
 138         a[i]  = q[ri];
 139         UPDATEQI(wi);
 140         UPDATEQI(ri);
 141       }
 142       s->wi[ch] = wi;
 143       break;
 144     }
 145     case 4:{
 146       int32_t* a = c->audio;
 147       int32_t* q = s->q[ch];
 148       int wi = s->wi[ch];
 149       ri = s->ri;
 150       for(i=ch;i<len;i+=nch){
 151         q[wi] = a[i];
 152         a[i]  = q[ri];
 153         UPDATEQI(wi);
 154         UPDATEQI(ri);
 155       }
 156       s->wi[ch] = wi;
 157       break;
 158     }
 159     }
 160   }
 161   s->ri = ri;
 162   return c;
 163 }
 164
 165 // Allocate memory and set function pointers
 166 static int af_open(af_instance_t* af){
 167   af->control=control;
 168   af->uninit=uninit;
 169   af->play=play;
 170   af->mul=1;
 171   af->data=calloc(1,sizeof(af_data_t));
 172   af->setup=calloc(1,sizeof(af_delay_t));
 173   if(af->data == NULL || af->setup == NULL)
 174     return AF_ERROR;
 175   return AF_OK;
 176 }
 177
 178 // Description of this filter
 179 af_info_t af_info_delay = {
 180     "Delay audio filter",
 181     "delay",
 182     "Anders",
 183     "",
 184     AF_FLAGS_REENTRANT,
 185     af_open
 186 };
 187
 188