summaryrefslogtreecommitdiffstats
path: root/apps/replaygain.c
blob: b398afc294b87e0c5c8225c62a4a9f68a2fba122 (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
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
/***************************************************************************
 *             __________               __   ___.
 *   Open      \______   \ ____   ____ |  | _\_ |__   _______  ___
 *   Source     |       _//  _ \_/ ___\|  |/ /| __ \ /  _ \  \/  /
 *   Jukebox    |    |   (  <_> )  \___|    < | \_\ (  <_> > <  <
 *   Firmware   |____|_  /\____/ \___  >__|_ \|___  /\____/__/\_ \
 *                     \/            \/     \/    \/            \/
 * $Id$
 *
 * Copyright (C) 2005 Magnus Holmgren
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 *
 * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
 * KIND, either express or implied.
 *
 ****************************************************************************/

#include <ctype.h>
#include <inttypes.h>
#include <math.h>
#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <system.h>
#include "metadata.h"
#include "debug.h"
#include "replaygain.h"
#include "fixedpoint.h"

#define FP_BITS         (12)
#define FP_ONE          (1 << FP_BITS)


static long fp_atof(const char* s, int precision)
{
    long int_part = 0;
    long int_one = BIT_N(precision);
    long frac_part = 0;
    long frac_count = 0;
    long frac_max = ((precision * 4) + 12) / 13;
    long frac_max_int = 1;
    long sign = 1;
    bool point = false;

    while ((*s != '\0') && isspace(*s))
    { 	 
        s++; 	 
    }

    if (*s == '-')
    {
        sign = -1;
        s++;
    }
    else if (*s == '+')
    {
        s++;
    }

    while (*s != '\0')
    {
        if (*s == '.')
        {
            if (point)
            {
                break;
            }

            point = true;
        }
        else if (isdigit(*s))
        {
            if (point)
            {
                if (frac_count < frac_max)
                {
                    frac_part = frac_part * 10 + (*s - '0');
                    frac_count++;
                    frac_max_int *= 10;
                }
            }
            else
            {
                int_part = int_part * 10 + (*s - '0');
            }
        }
        else
        {
            break;
        }

        s++;
    }

    while (frac_count < frac_max)
    {
      frac_part *= 10;
      frac_count++;
      frac_max_int *= 10;
    }

    return sign * ((int_part * int_one)
        + (((int64_t) frac_part * int_one) / frac_max_int));
}

static long convert_gain(long gain)
{
    /* Don't allow unreasonably low or high gain changes.
     * Our math code can't handle it properly anyway. :)
     */
    if (gain < (-48 * FP_ONE))
    {
        gain = -48 * FP_ONE;
    }

    if (gain > (17 * FP_ONE))
    {
        gain = 17 * FP_ONE;
    }

    gain = fp_factor(gain, FP_BITS) << (24 - FP_BITS);

    return gain;
}

/* Get the sample scale factor in Q7.24 format from a gain value. Returns 0
 * for no gain.
 *
 * str  Gain in dB as a string. E.g., "-3.45 dB"; the "dB" part is ignored.
 */
static long get_replaygain(const char* str)
{
    long gain = 0;

    if (str)
    {
        gain = fp_atof(str, FP_BITS);
        gain = convert_gain(gain);
    }

    return gain;
}

/* Get the peak volume in Q7.24 format.
 *
 * str  Peak volume. Full scale is specified as "1.0". Returns 0 for no peak.
 */
static long get_replaypeak(const char* str)
{
    long peak = 0;

    if (str)
    {
        peak = fp_atof(str, 24);
    }

    return peak;
}

/* Get a sample scale factor in Q7.24 format from a gain value.
 *
 * int_gain  Gain in dB, multiplied by 100.
 */
long get_replaygain_int(long int_gain)
{
    return convert_gain(int_gain * FP_ONE / 100);
}

/* Parse a ReplayGain tag conforming to the "VorbisGain standard". If a
 * valid tag is found, update mp3entry struct accordingly. Existing values 
 * are not overwritten. Returns number of bytes written to buffer.
 *
 * key     Name of the tag.
 * value   Value of the tag.
 * entry   mp3entry struct to update.
 * buffer  Where to store the text for gain values (for later display).
 * length  Bytes left in buffer.
 */
long parse_replaygain(const char* key, const char* value,
    struct mp3entry* entry, char* buffer, int length)
{
    char **p = NULL;

    if (((strcasecmp(key, "replaygain_track_gain") == 0)
        || (strcasecmp(key, "rg_radio") == 0)) && !entry->track_gain)
    {
        entry->track_gain = get_replaygain(value);
        p = &(entry->track_gain_string);
    }
    else if (((strcasecmp(key, "replaygain_album_gain") == 0)
        || (strcasecmp(key, "rg_audiophile") == 0)) && !entry->album_gain)
    {
        entry->album_gain = get_replaygain(value);
        p = &(entry->album_gain_string);
    }
    else if (((strcasecmp(key, "replaygain_track_peak") == 0)
        || (strcasecmp(key, "rg_peak") == 0)) && !entry->track_peak)
    {
        entry->track_peak = get_replaypeak(value);
    }
    else if ((strcasecmp(key, "replaygain_album_peak") == 0)
        && !entry->album_peak)
    {
        entry->album_peak = get_replaypeak(value);
    }

    if (p)
    {
        int len = strlen(value);

        len = MIN(len, length - 1);

        /* A few characters just isn't interesting... */
        if (len > 1)
        {
            strncpy(buffer, value, len);
            buffer[len] = 0;
            *p = buffer;
            return len + 1;
        }
    }

    return 0;
}

/* Set ReplayGain values from integers. Existing values are not overwritten. 
 * Returns number of bytes written to buffer.
 *
 * album   If true, set album values, otherwise set track values.
 * gain    Gain value in dB, multiplied by 512. 0 for no gain.
 * peak    Peak volume in Q7.24 format, where 1.0 is full scale. 0 for no 
 *         peak volume.
 * buffer  Where to store the text for gain values (for later display).
 * length  Bytes left in buffer.
 */
long parse_replaygain_int(bool album, long gain, long peak,
    struct mp3entry* entry, char* buffer, int length)
{
    long len = 0;

    if (buffer != NULL)
    {
        len = snprintf(buffer, length, "%d.%02d dB", gain / 512,
            ((abs(gain) & 0x01ff) * 100 + 256) / 512);
        len++;
    }

    if (gain != 0)
    {
        gain = convert_gain(gain * FP_ONE / 512);
    }

    if (album)
    {
        entry->album_gain = gain;
        entry->album_gain_string = buffer;

        if (peak)
        {
            entry->album_peak = peak;
        }
    }
    else
    {
        entry->track_gain = gain;
        entry->track_gain_string = buffer;

        if (peak)
        {
            entry->track_peak = peak;
        }
    }
    
    return len;
}