aboutsummaryrefslogtreecommitdiffhomepage
path: root/libao2/pl_volume.c
blob: a6590cce1644aa9da1a529ee6e787944a4f9f51e (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
/* This audio output plugin changes the volume of the sound, and can
   be used when the mixer doesn't support the PCM channel. The volume
   is set in fixed steps between 0 - 2^8. */

#define PLUGIN

// Some limits
#define MIN_S16 -32650
#define MAX_S16  32650
#define MIN_U8   0
#define MAX_U8   255
#define MIN_S8  -128
#define MAX_S8   127

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <inttypes.h>

#include "audio_out.h"
#include "audio_plugin.h"
#include "audio_plugin_internal.h"
#include "afmt.h"

static ao_info_t info =
{
        "Volume control audio plugin",
        "volume",
        "Anders",
        ""
};

LIBAO_PLUGIN_EXTERN(volume)

// local data
typedef struct pl_volume_s
{
  uint16_t volume;   	// output volume level
  int      inuse;     	// This plugin is in use TRUE, FALSE
  int      format;	// sample fomat
} pl_volume_t;

static pl_volume_t pl_volume={0,0,0};

// to set/get/query special features/parameters
static int control(int cmd,int arg){
  switch(cmd){
  case AOCONTROL_PLUGIN_SET_LEN:
    return CONTROL_OK;
  case AOCONTROL_GET_VOLUME:{
    if(pl_volume.inuse){
      ((ao_control_vol_t *)arg)->right=((float)pl_volume.volume)/2.55;
      ((ao_control_vol_t *)arg)->left=((float)pl_volume.volume)/2.55;
      return CONTROL_OK;
    }
    else
      return CONTROL_ERROR;
  }
  case AOCONTROL_SET_VOLUME:{
    if(pl_volume.inuse){
      // Calculate avarage between left and right
      float vol =2.55*((((ao_control_vol_t *)arg)->right)+(((ao_control_vol_t *)arg)->left))/2;
      pl_volume.volume=(uint16_t)vol;
      // Volume must be between 0 and 255
      if(vol > 255)
	pl_volume.volume = 0xFF;
      if(vol < 0)
	pl_volume.volume = 0;
      return CONTROL_OK;
    }
    else
      return CONTROL_ERROR;
  }
  }
  return CONTROL_UNKNOWN;
}

// open & setup audio device
// return: 1=success 0=fail
static int init(){
  // Sanity sheck this plugin supports AFMT_U8 and AFMT_S16_LE
  switch(ao_plugin_data.format){
  case(AFMT_U8):
  case(AFMT_S16_LE):
    break;
  default: 
    fprintf(stderr,"[pl_volume] Audio format not yet suported \n");
    return 0;
  }
  // Initialize volume to this value
  pl_volume.volume=ao_plugin_cfg.pl_volume_volume;
  pl_volume.format=ao_plugin_data.format;
  /* The inuse flag is used in control to detremine if the return
  value since that function always is called from ao_plugin regardless
  of wether this plugin is in use or not. */
  pl_volume.inuse=1;
  // Tell the world what we are up to
  printf("[pl_volume] Software volume control in use%s.\n",ao_plugin_cfg.pl_volume_softclip?", soft clipping enabled":"");
  return 1;
}

// close plugin
static void uninit(){
  pl_volume.inuse=0;
}

// empty buffers
static void reset(){
}

#define SIGN(x) (x>0?1:-1) 
// processes 'ao_plugin_data.len' bytes of 'data'
// called for every block of data
static int play(){
  register int i=0;
  register int vol=pl_volume.volume; // Logarithmic control sounds more natural
  vol=(vol*vol*vol)>>12;
  // Change the volume.
  switch(pl_volume.format){
  case(AFMT_U8):{
    register uint8_t* data=(uint8_t*)ao_plugin_data.data;
    register int x;
      for(i=0;i<ao_plugin_data.len;i++){
        x=((data[i]-128) * vol) >> 8; 
        if(x>MAX_S8)
	  data[i]=MAX_U8;
	  else if(x<MIN_S8)
	  data[i]=MIN_U8;
        else{
	  if(ao_plugin_cfg.pl_volume_softclip)
	    data[i] = ((3*x - ((x*x*x) >> 14)) >> 1) + 128;
	  else
	    data[i] = x + 128;
	}
      }
      break;
  }
  case(AFMT_S16_LE):{
    register int len=ao_plugin_data.len>>1;
    register int16_t* data=(int16_t*)ao_plugin_data.data;
    register int x;
    for(i=0;i<len;i++){
      x=(data[i] * vol) >> 8;
      if(x>MAX_S16)
	data[i]=MAX_S16;
      else if(x<MIN_S16)
	data[i]=MIN_S16;
      else{
	if(ao_plugin_cfg.pl_volume_softclip){
	  int64_t t=x*x;
	  t=(t*x) >> 30;
	  data[i] = (3*x - (int)t) >> 1;
	  //data[i] = 2*x - SIGN(x)*((x*x)>>15);
	}
	else
	  data[i] = x;
      }
    }
    break;
  }
  default: 
    return 0;
  }
  return 1;

}