libaf/af_extrastereo.c

   1 /*=============================================================================
   2 //
   3 //  This software has been released under the terms of the GNU General Public
   4 //  license. See http://www.gnu.org/copyleft/gpl.html for details.
   5 //
   6 //  Copyright 2004 Alex Beregszaszi & Pierre Lombard
   7 //
   8 //=============================================================================
   9 */
  10
  11 #include <stdio.h>
  12 #include <stdlib.h>
  13 #include <string.h>
  14
  15 #include <unistd.h>
  16 #include <inttypes.h>
  17 #include <math.h>
  18 #include <limits.h>
  19
  20 #include "af.h"
  21
  22 // Data for specific instances of this filter
  23 typedef struct af_extrastereo_s
  24 {
  25     float mul;
  26 }af_extrastereo_t;
  27
  28 static af_data_t* play_s16(struct af_instance_s* af, af_data_t* data);
  29 static af_data_t* play_float(struct af_instance_s* af, af_data_t* data);
  30
  31 // Initialization and runtime control
  32 static int control(struct af_instance_s* af, int cmd, void* arg)
  33 {
  34   af_extrastereo_t* s   = (af_extrastereo_t*)af->setup;
  35
  36   switch(cmd){
  37   case AF_CONTROL_REINIT:{
  38     // Sanity check
  39     if(!arg) return AF_ERROR;
  40
  41     af->data->rate   = ((af_data_t*)arg)->rate;
  42     af->data->nch    = 2;
  43     if (((af_data_t*)arg)->format == AF_FORMAT_FLOAT_NE)
  44     {
  45         af->data->format = AF_FORMAT_FLOAT_NE;
  46         af->data->bps = 4;
  47         af->play = play_float;
  48     }// else
  49     {
  50         af->data->format = AF_FORMAT_S16_NE;
  51         af->data->bps = 2;
  52         af->play = play_s16;
  53     }
  54
  55     return af_test_output(af,(af_data_t*)arg);
  56   }
  57   case AF_CONTROL_COMMAND_LINE:{
  58     float f;
  59     sscanf((char*)arg,"%f", &f);
  60     s->mul = f;
  61     return AF_OK;
  62   }
  63   case AF_CONTROL_ES_MUL | AF_CONTROL_SET:
  64     s->mul = *(float*)arg;
  65     return AF_OK;
  66   case AF_CONTROL_ES_MUL | AF_CONTROL_GET:
  67     *(float*)arg = s->mul;
  68     return AF_OK;
  69   }
  70   return AF_UNKNOWN;
  71 }
  72
  73 // Deallocate memory
  74 static void uninit(struct af_instance_s* af)
  75 {
  76   if(af->data)
  77     free(af->data);
  78   if(af->setup)
  79     free(af->setup);
  80 }
  81
  82 // Filter data through filter
  83 static af_data_t* play_s16(struct af_instance_s* af, af_data_t* data)
  84 {
  85   af_extrastereo_t *s = af->setup;
  86   register int i = 0;
  87   int16_t *a = (int16_t*)data->audio;   // Audio data
  88   int len = data->len/2;                // Number of samples
  89   int avg, l, r;
  90
  91   for (i = 0; i < len; i+=2)
  92   {
  93     avg = (a[i] + a[i + 1]) / 2;
  94
  95     l = avg + (int)(s->mul * (a[i] - avg));
  96     r = avg + (int)(s->mul * (a[i + 1] - avg));
  97
  98     a[i] = clamp(l, SHRT_MIN, SHRT_MAX);
  99     a[i + 1] = clamp(r, SHRT_MIN, SHRT_MAX);
 100   }
 101
 102   return data;
 103 }
 104
 105 static af_data_t* play_float(struct af_instance_s* af, af_data_t* data)
 106 {
 107   af_extrastereo_t *s = af->setup;
 108   register int i = 0;
 109   float *a = (float*)data->audio;       // Audio data
 110   int len = data->len/4;                // Number of samples
 111   float avg, l, r;
 112
 113   for (i = 0; i < len; i+=2)
 114   {
 115     avg = (a[i] + a[i + 1]) / 2;
 116
 117     l = avg + (s->mul * (a[i] - avg));
 118     r = avg + (s->mul * (a[i + 1] - avg));
 119
 120     a[i] = af_softclip(l);
 121     a[i + 1] = af_softclip(r);
 122   }
 123
 124   return data;
 125 }
 126
 127 // Allocate memory and set function pointers
 128 static int open(af_instance_t* af){
 129   af->control=control;
 130   af->uninit=uninit;
 131   af->play=play_s16;
 132   af->mul.n=1;
 133   af->mul.d=1;
 134   af->data=calloc(1,sizeof(af_data_t));
 135   af->setup=calloc(1,sizeof(af_extrastereo_t));
 136   if(af->data == NULL || af->setup == NULL)
 137     return AF_ERROR;
 138
 139   ((af_extrastereo_t*)af->setup)->mul = 2.5;
 140   return AF_OK;
 141 }
 142
 143 // Description of this filter
 144 af_info_t af_info_extrastereo = {
 145     "Extra stereo",
 146     "extrastereo",
 147     "Alex Beregszaszi & Pierre Lombard",
 148     "",
 149     AF_FLAGS_NOT_REENTRANT,
 150     open
 151 };