libaf/af_extrastereo.c

   1 /*
   2  * Copyright (C) 2004 Alex Beregszaszi & Pierre Lombard
   3  *
   4  * This file is part of MPlayer.
   5  *
   6  * MPlayer is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License as published by
   8  * the Free Software Foundation; either version 2 of the License, or
   9  * (at your option) any later version.
  10  *
  11  * MPlayer is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14  * GNU General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU General Public License along
  17  * with MPlayer; if not, write to the Free Software Foundation, Inc.,
  18  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  19  */
  20
  21 #include <stdio.h>
  22 #include <stdlib.h>
  23 #include <string.h>
  24
  25 #include <inttypes.h>
  26 #include <math.h>
  27 #include <limits.h>
  28
  29 #include "af.h"
  30
  31 // Data for specific instances of this filter
  32 typedef struct af_extrastereo_s
  33 {
  34     float mul;
  35 }af_extrastereo_t;
  36
  37 static af_data_t* play_s16(struct af_instance_s* af, af_data_t* data);
  38 static af_data_t* play_float(struct af_instance_s* af, af_data_t* data);
  39
  40 // Initialization and runtime control
  41 static int control(struct af_instance_s* af, int cmd, void* arg)
  42 {
  43   af_extrastereo_t* s   = (af_extrastereo_t*)af->setup;
  44
  45   switch(cmd){
  46   case AF_CONTROL_REINIT:{
  47     // Sanity check
  48     if(!arg) return AF_ERROR;
  49
  50     af->data->rate   = ((af_data_t*)arg)->rate;
  51     af->data->nch    = 2;
  52     if (((af_data_t*)arg)->format == AF_FORMAT_FLOAT_NE)
  53     {
  54         af->data->format = AF_FORMAT_FLOAT_NE;
  55         af->data->bps = 4;
  56         af->play = play_float;
  57     }// else
  58     {
  59         af->data->format = AF_FORMAT_S16_NE;
  60         af->data->bps = 2;
  61         af->play = play_s16;
  62     }
  63
  64     return af_test_output(af,(af_data_t*)arg);
  65   }
  66   case AF_CONTROL_COMMAND_LINE:{
  67     float f;
  68     sscanf((char*)arg,"%f", &f);
  69     s->mul = f;
  70     return AF_OK;
  71   }
  72   case AF_CONTROL_ES_MUL | AF_CONTROL_SET:
  73     s->mul = *(float*)arg;
  74     return AF_OK;
  75   case AF_CONTROL_ES_MUL | AF_CONTROL_GET:
  76     *(float*)arg = s->mul;
  77     return AF_OK;
  78   }
  79   return AF_UNKNOWN;
  80 }
  81
  82 // Deallocate memory
  83 static void uninit(struct af_instance_s* af)
  84 {
  85     free(af->data);
  86     free(af->setup);
  87 }
  88
  89 // Filter data through filter
  90 static af_data_t* play_s16(struct af_instance_s* af, af_data_t* data)
  91 {
  92   af_extrastereo_t *s = af->setup;
  93   register int i = 0;
  94   int16_t *a = (int16_t*)data->audio;   // Audio data
  95   int len = data->len/2;                // Number of samples
  96   int avg, l, r;
  97
  98   for (i = 0; i < len; i+=2)
  99   {
 100     avg = (a[i] + a[i + 1]) / 2;
 101
 102     l = avg + (int)(s->mul * (a[i] - avg));
 103     r = avg + (int)(s->mul * (a[i + 1] - avg));
 104
 105     a[i] = clamp(l, SHRT_MIN, SHRT_MAX);
 106     a[i + 1] = clamp(r, SHRT_MIN, SHRT_MAX);
 107   }
 108
 109   return data;
 110 }
 111
 112 static af_data_t* play_float(struct af_instance_s* af, af_data_t* data)
 113 {
 114   af_extrastereo_t *s = af->setup;
 115   register int i = 0;
 116   float *a = (float*)data->audio;       // Audio data
 117   int len = data->len/4;                // Number of samples
 118   float avg, l, r;
 119
 120   for (i = 0; i < len; i+=2)
 121   {
 122     avg = (a[i] + a[i + 1]) / 2;
 123
 124     l = avg + (s->mul * (a[i] - avg));
 125     r = avg + (s->mul * (a[i + 1] - avg));
 126
 127     a[i] = af_softclip(l);
 128     a[i + 1] = af_softclip(r);
 129   }
 130
 131   return data;
 132 }
 133
 134 // Allocate memory and set function pointers
 135 static int af_open(af_instance_t* af){
 136   af->control=control;
 137   af->uninit=uninit;
 138   af->play=play_s16;
 139   af->mul=1;
 140   af->data=calloc(1,sizeof(af_data_t));
 141   af->setup=calloc(1,sizeof(af_extrastereo_t));
 142   if(af->data == NULL || af->setup == NULL)
 143     return AF_ERROR;
 144
 145   ((af_extrastereo_t*)af->setup)->mul = 2.5;
 146   return AF_OK;
 147 }
 148
 149 // Description of this filter
 150 af_info_t af_info_extrastereo = {
 151     "Increase difference between audio channels",
 152     "extrastereo",
 153     "Alex Beregszaszi & Pierre Lombard",
 154     "",
 155     AF_FLAGS_NOT_REENTRANT,
 156     af_open
 157 };