summaryrefslogtreecommitdiffstats
path: root/apps/replaygain.c
blob: 8f6fe4c7384061f4be6dbd4fa12e1622352aea1f (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
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
/***************************************************************************
 *             __________               __   ___.
 *   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"

/* The fixed point math routines (with the exception of fp_atof) are based
 * on oMathFP by Dan Carter (http://orbisstudios.com).
 */

/* 12 bits of precision gives fairly accurate result, but still allows a
 * compact implementation. The math code supports up to 13...
 */

#define FP_BITS         (12)
#define FP_MASK         ((1 << FP_BITS) - 1)
#define FP_ONE          (1 << FP_BITS)
#define FP_TWO          (2 << FP_BITS)
#define FP_HALF         (1 << (FP_BITS - 1))
#define FP_LN2          ( 45426 >> (16 - FP_BITS))
#define FP_LN2_INV      ( 94548 >> (16 - FP_BITS))
#define FP_EXP_ZERO     ( 10922 >> (16 - FP_BITS))
#define FP_EXP_ONE      (  -182 >> (16 - FP_BITS))
#define FP_EXP_TWO      (     4 >> (16 - FP_BITS))
#define FP_INF          (0x7fffffff)
#define FP_LN10         (150902 >> (16 - FP_BITS))

#define FP_MAX_DIGITS       (4)
#define FP_MAX_DIGITS_INT   (10000)

#define FP_FAST_MUL_DIV

#ifdef FP_FAST_MUL_DIV

/* These macros can easily overflow, but they are good enough for our uses,
 * and saves some code.
 */
#define fp_mul(x, y) (((x) * (y)) >> FP_BITS)
#define fp_div(x, y) (((x) << FP_BITS) / (y))

#else

static long fp_mul(long x, long y)
{
    long x_neg = 0;
    long y_neg = 0;
    long rc;

    if ((x == 0) || (y == 0))
    {
        return 0;
    }

    if (x < 0)
    {
        x_neg = 1;
        x = -x;
    }

    if (y < 0)
    {
        y_neg = 1;
        y = -y;
    }

    rc = (((x >> FP_BITS) * (y >> FP_BITS)) << FP_BITS)
        + (((x & FP_MASK) * (y & FP_MASK)) >> FP_BITS)
        + ((x & FP_MASK) * (y >> FP_BITS))
        + ((x >> FP_BITS) * (y & FP_MASK));

    if ((x_neg ^ y_neg) == 1)
    {
        rc = -rc;
    }

    return rc;
}

static long fp_div(long x, long y)
{
    long x_neg = 0;
    long y_neg = 0;
    long shifty;
    long rc;
    int msb = 0;
    int lsb = 0;

    if (x == 0)
    {
        return 0;
    }

    if (y == 0)
    {
        return (x < 0) ? -FP_INF : FP_INF;
    }

    if (x < 0)
    {
        x_neg = 1;
        x = -x;
    }

    if (y < 0)
    {
        y_neg = 1;
        y = -y;
    }

    while ((x & (1 << (30 - msb))) == 0)
    {
        msb++;
    }

    while ((y & (1 << lsb)) == 0)
    {
        lsb++;
    }

    shifty = FP_BITS - (msb + lsb);
    rc = ((x << msb) / (y >> lsb));

    if (shifty > 0)
    {
        rc <<= shifty;
    }
    else
    {
        rc >>= -shifty;
    }

    if ((x_neg ^ y_neg) == 1)
    {
        rc = -rc;
    }

    return rc;
}

#endif /* FP_FAST_MUL_DIV */

static long fp_exp(long x)
{
    long k;
    long z;
    long R;
    long xp;

    if (x == 0)
    {
        return FP_ONE;
    }

    k = (fp_mul(abs(x), FP_LN2_INV) + FP_HALF) & ~FP_MASK;

    if (x < 0)
    {
        k = -k;
    }

    x -= fp_mul(k, FP_LN2);
    z = fp_mul(x, x);
    R = FP_TWO + fp_mul(z, FP_EXP_ZERO + fp_mul(z, FP_EXP_ONE
        + fp_mul(z, FP_EXP_TWO)));
    xp = FP_ONE + fp_div(fp_mul(FP_TWO, x), R - x);

    if (k < 0)
    {
        k = FP_ONE >> (-k >> FP_BITS);
    }
    else
    {
        k = FP_ONE << (k >> FP_BITS);
    }

    return fp_mul(k, xp);
}

static long fp_exp10(long x)
{
    if (x == 0)
    {
        return FP_ONE;
    }

    return fp_exp(fp_mul(FP_LN10, x));
}

static long fp_atof(const char* s, int precision)
{
    long int_part = 0;
    long int_one = 1 << 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_exp10(gain / 20) << (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;
}