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