deps/flac-1.3.2/src/share/grabbag/replaygain.c

   1 /* grabbag - Convenience lib for various routines common to several tools
   2  * Copyright (C) 2002-2009  Josh Coalson
   3  * Copyright (C) 2011-2016  Xiph.Org Foundation
   4  *
   5  * This library is free software; you can redistribute it and/or
   6  * modify it under the terms of the GNU Lesser General Public
   7  * License as published by the Free Software Foundation; either
   8  * version 2.1 of the License, or (at your option) any later version.
   9  *
  10  * This library is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13  * Lesser General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU Lesser General Public
  16  * License along with this library; if not, write to the Free Software
  17  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
  18  */
  19
  20 #ifdef HAVE_CONFIG_H
  21 #  include <config.h>
  22 #endif
  23
  24 #include <locale.h>
  25 #include <math.h>
  26 #include <stdio.h>
  27 #include <stdlib.h>
  28 #include <string.h>
  29 #if defined _MSC_VER || defined __MINGW32__
  30 #include <io.h> /* for chmod() */
  31 #endif
  32 #include <sys/stat.h> /* for stat(), maybe chmod() */
  33
  34 #include "FLAC/assert.h"
  35 #include "FLAC/metadata.h"
  36 #include "FLAC/stream_decoder.h"
  37 #include "share/grabbag.h"
  38 #include "share/replaygain_analysis.h"
  39 #include "share/safe_str.h"
  40
  41 #ifdef local_min
  42 #undef local_min
  43 #endif
  44 #define local_min(a,b) ((a)<(b)?(a):(b))
  45
  46 #ifdef local_max
  47 #undef local_max
  48 #endif
  49 #define local_max(a,b) ((a)>(b)?(a):(b))
  50
  51 static const char *reference_format_ = "%s=%2.1f dB";
  52 static const char *gain_format_ = "%s=%+2.2f dB";
  53 static const char *peak_format_ = "%s=%1.8f";
  54
  55 static double album_peak_, title_peak_;
  56
  57 const unsigned GRABBAG__REPLAYGAIN_MAX_TAG_SPACE_REQUIRED = 190;
  58 /*
  59         FLAC__STREAM_METADATA_VORBIS_COMMENT_ENTRY_LENGTH_LEN/8 + 29 + 1 + 8 +
  60         FLAC__STREAM_METADATA_VORBIS_COMMENT_ENTRY_LENGTH_LEN/8 + 21 + 1 + 10 +
  61         FLAC__STREAM_METADATA_VORBIS_COMMENT_ENTRY_LENGTH_LEN/8 + 21 + 1 + 12 +
  62         FLAC__STREAM_METADATA_VORBIS_COMMENT_ENTRY_LENGTH_LEN/8 + 21 + 1 + 10 +
  63         FLAC__STREAM_METADATA_VORBIS_COMMENT_ENTRY_LENGTH_LEN/8 + 21 + 1 + 12
  64 */
  65
  66 const FLAC__byte * const GRABBAG__REPLAYGAIN_TAG_REFERENCE_LOUDNESS = (const FLAC__byte * const)"REPLAYGAIN_REFERENCE_LOUDNESS";
  67 const FLAC__byte * const GRABBAG__REPLAYGAIN_TAG_TITLE_GAIN = (const FLAC__byte * const)"REPLAYGAIN_TRACK_GAIN";
  68 const FLAC__byte * const GRABBAG__REPLAYGAIN_TAG_TITLE_PEAK = (const FLAC__byte * const)"REPLAYGAIN_TRACK_PEAK";
  69 const FLAC__byte * const GRABBAG__REPLAYGAIN_TAG_ALBUM_GAIN = (const FLAC__byte * const)"REPLAYGAIN_ALBUM_GAIN";
  70 const FLAC__byte * const GRABBAG__REPLAYGAIN_TAG_ALBUM_PEAK = (const FLAC__byte * const)"REPLAYGAIN_ALBUM_PEAK";
  71
  72
  73 static FLAC__bool get_file_stats_(const char *filename, struct flac_stat_s *stats)
  74 {
  75         FLAC__ASSERT(0 != filename);
  76         FLAC__ASSERT(0 != stats);
  77         return (0 == flac_stat(filename, stats));
  78 }
  79
  80 static void set_file_stats_(const char *filename, struct flac_stat_s *stats)
  81 {
  82         FLAC__ASSERT(0 != filename);
  83         FLAC__ASSERT(0 != stats);
  84
  85         (void)flac_chmod(filename, stats->st_mode);
  86 }
  87
  88 static FLAC__bool append_tag_(FLAC__StreamMetadata *block, const char *format, const FLAC__byte *name, float value)
  89 {
  90         char buffer[256];
  91         char *saved_locale;
  92         FLAC__StreamMetadata_VorbisComment_Entry entry;
  93
  94         FLAC__ASSERT(0 != block);
  95         FLAC__ASSERT(block->type == FLAC__METADATA_TYPE_VORBIS_COMMENT);
  96         FLAC__ASSERT(0 != format);
  97         FLAC__ASSERT(0 != name);
  98
  99         buffer[sizeof(buffer)-1] = '\0';
 100         /*
 101          * We need to save the old locale and switch to "C" because the locale
 102          * influences the formatting of %f and we want it a certain way.
 103          */
 104         saved_locale = strdup(setlocale(LC_ALL, 0));
 105         if (0 == saved_locale)
 106                 return false;
 107         setlocale(LC_ALL, "C");
 108         flac_snprintf(buffer, sizeof(buffer), format, name, value);
 109         setlocale(LC_ALL, saved_locale);
 110         free(saved_locale);
 111
 112         entry.entry = (FLAC__byte *)buffer;
 113         entry.length = strlen(buffer);
 114
 115         return FLAC__metadata_object_vorbiscomment_append_comment(block, entry, /*copy=*/true);
 116 }
 117
 118 FLAC__bool grabbag__replaygain_is_valid_sample_frequency(unsigned sample_frequency)
 119 {
 120         return ValidGainFrequency( sample_frequency );
 121 }
 122
 123 FLAC__bool grabbag__replaygain_init(unsigned sample_frequency)
 124 {
 125         title_peak_ = album_peak_ = 0.0;
 126         return InitGainAnalysis((long)sample_frequency) == INIT_GAIN_ANALYSIS_OK;
 127 }
 128
 129 FLAC__bool grabbag__replaygain_analyze(const FLAC__int32 * const input[], FLAC__bool is_stereo, unsigned bps, unsigned samples)
 130 {
 131         /* using a small buffer improves data locality; we'd like it to fit easily in the dcache */
 132         static flac_float_t lbuffer[2048], rbuffer[2048];
 133         static const unsigned nbuffer = sizeof(lbuffer) / sizeof(lbuffer[0]);
 134         FLAC__int32 block_peak = 0, s;
 135         unsigned i, j;
 136
 137         FLAC__ASSERT(bps >= 4 && bps <= FLAC__REFERENCE_CODEC_MAX_BITS_PER_SAMPLE);
 138         FLAC__ASSERT(FLAC__MIN_BITS_PER_SAMPLE == 4);
 139         /*
 140          * We use abs() on a FLAC__int32 which is undefined for the most negative value.
 141          * If the reference codec ever handles 32bps we will have to write a special
 142          * case here.
 143          */
 144         FLAC__ASSERT(FLAC__REFERENCE_CODEC_MAX_BITS_PER_SAMPLE < 32);
 145
 146         if(bps == 16) {
 147                 if(is_stereo) {
 148                         j = 0;
 149                         while(samples > 0) {
 150                                 const unsigned n = local_min(samples, nbuffer);
 151                                 for(i = 0; i < n; i++, j++) {
 152                                         s = input[0][j];
 153                                         lbuffer[i] = (flac_float_t)s;
 154                                         s = abs(s);
 155                                         block_peak = local_max(block_peak, s);
 156
 157                                         s = input[1][j];
 158                                         rbuffer[i] = (flac_float_t)s;
 159                                         s = abs(s);
 160                                         block_peak = local_max(block_peak, s);
 161                                 }
 162                                 samples -= n;
 163                                 if(AnalyzeSamples(lbuffer, rbuffer, n, 2) != GAIN_ANALYSIS_OK)
 164                                         return false;
 165                         }
 166                 }
 167                 else {
 168                         j = 0;
 169                         while(samples > 0) {
 170                                 const unsigned n = local_min(samples, nbuffer);
 171                                 for(i = 0; i < n; i++, j++) {
 172                                         s = input[0][j];
 173                                         lbuffer[i] = (flac_float_t)s;
 174                                         s = abs(s);
 175                                         block_peak = local_max(block_peak, s);
 176                                 }
 177                                 samples -= n;
 178                                 if(AnalyzeSamples(lbuffer, 0, n, 1) != GAIN_ANALYSIS_OK)
 179                                         return false;
 180                         }
 181                 }
 182         }
 183         else { /* bps must be < 32 according to above assertion */
 184                 const double scale = (
 185                         (bps > 16)?
 186                                 (double)1. / (double)(1u << (bps - 16)) :
 187                                 (double)(1u << (16 - bps))
 188                 );
 189
 190                 if(is_stereo) {
 191                         j = 0;
 192                         while(samples > 0) {
 193                                 const unsigned n = local_min(samples, nbuffer);
 194                                 for(i = 0; i < n; i++, j++) {
 195                                         s = input[0][j];
 196                                         lbuffer[i] = (flac_float_t)(scale * (double)s);
 197                                         s = abs(s);
 198                                         block_peak = local_max(block_peak, s);
 199
 200                                         s = input[1][j];
 201                                         rbuffer[i] = (flac_float_t)(scale * (double)s);
 202                                         s = abs(s);
 203                                         block_peak = local_max(block_peak, s);
 204                                 }
 205                                 samples -= n;
 206                                 if(AnalyzeSamples(lbuffer, rbuffer, n, 2) != GAIN_ANALYSIS_OK)
 207                                         return false;
 208                         }
 209                 }
 210                 else {
 211                         j = 0;
 212                         while(samples > 0) {
 213                                 const unsigned n = local_min(samples, nbuffer);
 214                                 for(i = 0; i < n; i++, j++) {
 215                                         s = input[0][j];
 216                                         lbuffer[i] = (flac_float_t)(scale * (double)s);
 217                                         s = abs(s);
 218                                         block_peak = local_max(block_peak, s);
 219                                 }
 220                                 samples -= n;
 221                                 if(AnalyzeSamples(lbuffer, 0, n, 1) != GAIN_ANALYSIS_OK)
 222                                         return false;
 223                         }
 224                 }
 225         }
 226
 227         {
 228                 const double peak_scale = (double)(1u << (bps - 1));
 229                 double peak = (double)block_peak / peak_scale;
 230                 if(peak > title_peak_)
 231                         title_peak_ = peak;
 232                 if(peak > album_peak_)
 233                         album_peak_ = peak;
 234         }
 235
 236         return true;
 237 }
 238
 239 void grabbag__replaygain_get_album(float *gain, float *peak)
 240 {
 241         *gain = (float)GetAlbumGain();
 242         *peak = (float)album_peak_;
 243         album_peak_ = 0.0;
 244 }
 245
 246 void grabbag__replaygain_get_title(float *gain, float *peak)
 247 {
 248         *gain = (float)GetTitleGain();
 249         *peak = (float)title_peak_;
 250         title_peak_ = 0.0;
 251 }
 252
 253
 254 typedef struct {
 255         unsigned channels;
 256         unsigned bits_per_sample;
 257         unsigned sample_rate;
 258         FLAC__bool error;
 259 } DecoderInstance;
 260
 261 static FLAC__StreamDecoderWriteStatus write_callback_(const FLAC__StreamDecoder *decoder, const FLAC__Frame *frame, const FLAC__int32 * const buffer[], void *client_data)
 262 {
 263         DecoderInstance *instance = (DecoderInstance*)client_data;
 264         const unsigned bits_per_sample = frame->header.bits_per_sample;
 265         const unsigned channels = frame->header.channels;
 266         const unsigned sample_rate = frame->header.sample_rate;
 267         const unsigned samples = frame->header.blocksize;
 268
 269         (void)decoder;
 270
 271         if(
 272                 !instance->error &&
 273                 (channels == 2 || channels == 1) &&
 274                 bits_per_sample == instance->bits_per_sample &&
 275                 channels == instance->channels &&
 276                 sample_rate == instance->sample_rate
 277         ) {
 278                 instance->error = !grabbag__replaygain_analyze(buffer, channels==2, bits_per_sample, samples);
 279         }
 280         else {
 281                 instance->error = true;
 282         }
 283
 284         if(!instance->error)
 285                 return FLAC__STREAM_DECODER_WRITE_STATUS_CONTINUE;
 286         else
 287                 return FLAC__STREAM_DECODER_WRITE_STATUS_ABORT;
 288 }
 289
 290 static void metadata_callback_(const FLAC__StreamDecoder *decoder, const FLAC__StreamMetadata *metadata, void *client_data)
 291 {
 292         DecoderInstance *instance = (DecoderInstance*)client_data;
 293
 294         (void)decoder;
 295
 296         if(metadata->type == FLAC__METADATA_TYPE_STREAMINFO) {
 297                 instance->bits_per_sample = metadata->data.stream_info.bits_per_sample;
 298                 instance->channels = metadata->data.stream_info.channels;
 299                 instance->sample_rate = metadata->data.stream_info.sample_rate;
 300
 301                 if(instance->channels != 1 && instance->channels != 2) {
 302                         instance->error = true;
 303                         return;
 304                 }
 305
 306                 if(!grabbag__replaygain_is_valid_sample_frequency(instance->sample_rate)) {
 307                         instance->error = true;
 308                         return;
 309                 }
 310         }
 311 }
 312
 313 static void error_callback_(const FLAC__StreamDecoder *decoder, FLAC__StreamDecoderErrorStatus status, void *client_data)
 314 {
 315         DecoderInstance *instance = (DecoderInstance*)client_data;
 316
 317         (void)decoder, (void)status;
 318
 319         instance->error = true;
 320 }
 321
 322 const char *grabbag__replaygain_analyze_file(const char *filename, float *title_gain, float *title_peak)
 323 {
 324         DecoderInstance instance;
 325         FLAC__StreamDecoder *decoder = FLAC__stream_decoder_new();
 326
 327         if(0 == decoder)
 328                 return "memory allocation error";
 329
 330         instance.error = false;
 331
 332         /* It does these three by default but lets be explicit: */
 333         FLAC__stream_decoder_set_md5_checking(decoder, false);
 334         FLAC__stream_decoder_set_metadata_ignore_all(decoder);
 335         FLAC__stream_decoder_set_metadata_respond(decoder, FLAC__METADATA_TYPE_STREAMINFO);
 336
 337         if(FLAC__stream_decoder_init_file(decoder, filename, write_callback_, metadata_callback_, error_callback_, &instance) != FLAC__STREAM_DECODER_INIT_STATUS_OK) {
 338                 FLAC__stream_decoder_delete(decoder);
 339                 return "initializing decoder";
 340         }
 341
 342         if(!FLAC__stream_decoder_process_until_end_of_stream(decoder) || instance.error) {
 343                 FLAC__stream_decoder_delete(decoder);
 344                 return "decoding file";
 345         }
 346
 347         FLAC__stream_decoder_delete(decoder);
 348
 349         grabbag__replaygain_get_title(title_gain, title_peak);
 350
 351         return 0;
 352 }
 353
 354 const char *grabbag__replaygain_store_to_vorbiscomment(FLAC__StreamMetadata *block, float album_gain, float album_peak, float title_gain, float title_peak)
 355 {
 356         const char *error;
 357
 358         if(0 != (error = grabbag__replaygain_store_to_vorbiscomment_reference(block)))
 359                 return error;
 360
 361         if(0 != (error = grabbag__replaygain_store_to_vorbiscomment_title(block, title_gain, title_peak)))
 362                 return error;
 363
 364         if(0 != (error = grabbag__replaygain_store_to_vorbiscomment_album(block, album_gain, album_peak)))
 365                 return error;
 366
 367         return 0;
 368 }
 369
 370 const char *grabbag__replaygain_store_to_vorbiscomment_reference(FLAC__StreamMetadata *block)
 371 {
 372         FLAC__ASSERT(0 != block);
 373         FLAC__ASSERT(block->type == FLAC__METADATA_TYPE_VORBIS_COMMENT);
 374
 375         if(FLAC__metadata_object_vorbiscomment_remove_entries_matching(block, (const char *)GRABBAG__REPLAYGAIN_TAG_REFERENCE_LOUDNESS) < 0)
 376                 return "memory allocation error";
 377
 378         if(!append_tag_(block, reference_format_, GRABBAG__REPLAYGAIN_TAG_REFERENCE_LOUDNESS, ReplayGainReferenceLoudness))
 379                 return "memory allocation error";
 380
 381         return 0;
 382 }
 383
 384 const char *grabbag__replaygain_store_to_vorbiscomment_album(FLAC__StreamMetadata *block, float album_gain, float album_peak)
 385 {
 386         FLAC__ASSERT(0 != block);
 387         FLAC__ASSERT(block->type == FLAC__METADATA_TYPE_VORBIS_COMMENT);
 388
 389         if(
 390                 FLAC__metadata_object_vorbiscomment_remove_entries_matching(block, (const char *)GRABBAG__REPLAYGAIN_TAG_ALBUM_GAIN) < 0 ||
 391                 FLAC__metadata_object_vorbiscomment_remove_entries_matching(block, (const char *)GRABBAG__REPLAYGAIN_TAG_ALBUM_PEAK) < 0
 392         )
 393                 return "memory allocation error";
 394
 395         if(
 396                 !append_tag_(block, gain_format_, GRABBAG__REPLAYGAIN_TAG_ALBUM_GAIN, album_gain) ||
 397                 !append_tag_(block, peak_format_, GRABBAG__REPLAYGAIN_TAG_ALBUM_PEAK, album_peak)
 398         )
 399                 return "memory allocation error";
 400
 401         return 0;
 402 }
 403
 404 const char *grabbag__replaygain_store_to_vorbiscomment_title(FLAC__StreamMetadata *block, float title_gain, float title_peak)
 405 {
 406         FLAC__ASSERT(0 != block);
 407         FLAC__ASSERT(block->type == FLAC__METADATA_TYPE_VORBIS_COMMENT);
 408
 409         if(
 410                 FLAC__metadata_object_vorbiscomment_remove_entries_matching(block, (const char *)GRABBAG__REPLAYGAIN_TAG_TITLE_GAIN) < 0 ||
 411                 FLAC__metadata_object_vorbiscomment_remove_entries_matching(block, (const char *)GRABBAG__REPLAYGAIN_TAG_TITLE_PEAK) < 0
 412         )
 413                 return "memory allocation error";
 414
 415         if(
 416                 !append_tag_(block, gain_format_, GRABBAG__REPLAYGAIN_TAG_TITLE_GAIN, title_gain) ||
 417                 !append_tag_(block, peak_format_, GRABBAG__REPLAYGAIN_TAG_TITLE_PEAK, title_peak)
 418         )
 419                 return "memory allocation error";
 420
 421         return 0;
 422 }
 423
 424 static const char *store_to_file_pre_(const char *filename, FLAC__Metadata_Chain **chain, FLAC__StreamMetadata **block)
 425 {
 426         FLAC__Metadata_Iterator *iterator;
 427         const char *error;
 428         FLAC__bool found_vc_block = false;
 429
 430         if(0 == (*chain = FLAC__metadata_chain_new()))
 431                 return "memory allocation error";
 432
 433         if(!FLAC__metadata_chain_read(*chain, filename)) {
 434                 error = FLAC__Metadata_ChainStatusString[FLAC__metadata_chain_status(*chain)];
 435                 FLAC__metadata_chain_delete(*chain);
 436                 return error;
 437         }
 438
 439         if(0 == (iterator = FLAC__metadata_iterator_new())) {
 440                 FLAC__metadata_chain_delete(*chain);
 441                 return "memory allocation error";
 442         }
 443
 444         FLAC__metadata_iterator_init(iterator, *chain);
 445
 446         do {
 447                 *block = FLAC__metadata_iterator_get_block(iterator);
 448                 if((*block)->type == FLAC__METADATA_TYPE_VORBIS_COMMENT)
 449                         found_vc_block = true;
 450         } while(!found_vc_block && FLAC__metadata_iterator_next(iterator));
 451
 452         if(!found_vc_block) {
 453                 /* create a new block */
 454                 *block = FLAC__metadata_object_new(FLAC__METADATA_TYPE_VORBIS_COMMENT);
 455                 if(0 == *block) {
 456                         FLAC__metadata_chain_delete(*chain);
 457                         FLAC__metadata_iterator_delete(iterator);
 458                         return "memory allocation error";
 459                 }
 460                 while(FLAC__metadata_iterator_next(iterator))
 461                         ;
 462                 if(!FLAC__metadata_iterator_insert_block_after(iterator, *block)) {
 463                         error = FLAC__Metadata_ChainStatusString[FLAC__metadata_chain_status(*chain)];
 464                         FLAC__metadata_chain_delete(*chain);
 465                         FLAC__metadata_iterator_delete(iterator);
 466                         return error;
 467                 }
 468                 /* iterator is left pointing to new block */
 469                 FLAC__ASSERT(FLAC__metadata_iterator_get_block(iterator) == *block);
 470         }
 471
 472         FLAC__metadata_iterator_delete(iterator);
 473
 474         FLAC__ASSERT(0 != *block);
 475         FLAC__ASSERT((*block)->type == FLAC__METADATA_TYPE_VORBIS_COMMENT);
 476
 477         return 0;
 478 }
 479
 480 static const char *store_to_file_post_(const char *filename, FLAC__Metadata_Chain *chain, FLAC__bool preserve_modtime)
 481 {
 482         struct flac_stat_s stats;
 483         const FLAC__bool have_stats = get_file_stats_(filename, &stats);
 484
 485         (void)grabbag__file_change_stats(filename, /*read_only=*/false);
 486
 487         FLAC__metadata_chain_sort_padding(chain);
 488         if(!FLAC__metadata_chain_write(chain, /*use_padding=*/true, preserve_modtime)) {
 489                 const char *error;
 490                 error = FLAC__Metadata_ChainStatusString[FLAC__metadata_chain_status(chain)];
 491                 FLAC__metadata_chain_delete(chain);
 492                 return error;
 493         }
 494
 495         FLAC__metadata_chain_delete(chain);
 496
 497         if(have_stats)
 498                 set_file_stats_(filename, &stats);
 499
 500         return 0;
 501 }
 502
 503 const char *grabbag__replaygain_store_to_file(const char *filename, float album_gain, float album_peak, float title_gain, float title_peak, FLAC__bool preserve_modtime)
 504 {
 505         FLAC__Metadata_Chain *chain;
 506         FLAC__StreamMetadata *block = NULL;
 507         const char *error;
 508
 509         if(0 != (error = store_to_file_pre_(filename, &chain, &block)))
 510                 return error;
 511
 512         if(0 != (error = grabbag__replaygain_store_to_vorbiscomment(block, album_gain, album_peak, title_gain, title_peak))) {
 513                 FLAC__metadata_chain_delete(chain);
 514                 return error;
 515         }
 516
 517         if(0 != (error = store_to_file_post_(filename, chain, preserve_modtime)))
 518                 return error;
 519
 520         return 0;
 521 }
 522
 523 const char *grabbag__replaygain_store_to_file_reference(const char *filename, FLAC__bool preserve_modtime)
 524 {
 525         FLAC__Metadata_Chain *chain;
 526         FLAC__StreamMetadata *block = NULL;
 527         const char *error;
 528
 529         if(0 != (error = store_to_file_pre_(filename, &chain, &block)))
 530                 return error;
 531
 532         if(0 != (error = grabbag__replaygain_store_to_vorbiscomment_reference(block))) {
 533                 FLAC__metadata_chain_delete(chain);
 534                 return error;
 535         }
 536
 537         if(0 != (error = store_to_file_post_(filename, chain, preserve_modtime)))
 538                 return error;
 539
 540         return 0;
 541 }
 542
 543 const char *grabbag__replaygain_store_to_file_album(const char *filename, float album_gain, float album_peak, FLAC__bool preserve_modtime)
 544 {
 545         FLAC__Metadata_Chain *chain;
 546         FLAC__StreamMetadata *block = NULL;
 547         const char *error;
 548
 549         if(0 != (error = store_to_file_pre_(filename, &chain, &block)))
 550                 return error;
 551
 552         if(0 != (error = grabbag__replaygain_store_to_vorbiscomment_album(block, album_gain, album_peak))) {
 553                 FLAC__metadata_chain_delete(chain);
 554                 return error;
 555         }
 556
 557         if(0 != (error = store_to_file_post_(filename, chain, preserve_modtime)))
 558                 return error;
 559
 560         return 0;
 561 }
 562
 563 const char *grabbag__replaygain_store_to_file_title(const char *filename, float title_gain, float title_peak, FLAC__bool preserve_modtime)
 564 {
 565         FLAC__Metadata_Chain *chain;
 566         FLAC__StreamMetadata *block = NULL;
 567         const char *error;
 568
 569         if(0 != (error = store_to_file_pre_(filename, &chain, &block)))
 570                 return error;
 571
 572         if(0 != (error = grabbag__replaygain_store_to_vorbiscomment_title(block, title_gain, title_peak))) {
 573                 FLAC__metadata_chain_delete(chain);
 574                 return error;
 575         }
 576
 577         if(0 != (error = store_to_file_post_(filename, chain, preserve_modtime)))
 578                 return error;
 579
 580         return 0;
 581 }
 582
 583 static FLAC__bool parse_double_(const FLAC__StreamMetadata_VorbisComment_Entry *entry, double *val)
 584 {
 585         char s[32], *end;
 586         const char *p, *q;
 587         double v;
 588
 589         FLAC__ASSERT(0 != entry);
 590         FLAC__ASSERT(0 != val);
 591
 592         p = (const char *)entry->entry;
 593         q = strchr(p, '=');
 594         if(0 == q)
 595                 return false;
 596         q++;
 597         safe_strncpy(s, q, local_min(sizeof(s), (size_t) (entry->length - (q-p))));
 598
 599         v = strtod(s, &end);
 600         if(end == s)
 601                 return false;
 602
 603         *val = v;
 604         return true;
 605 }
 606
 607 FLAC__bool grabbag__replaygain_load_from_vorbiscomment(const FLAC__StreamMetadata *block, FLAC__bool album_mode, FLAC__bool strict, double *reference, double *gain, double *peak)
 608 {
 609         int reference_offset, gain_offset, peak_offset;
 610         char *saved_locale;
 611         FLAC__bool res = true;
 612
 613         FLAC__ASSERT(0 != block);
 614         FLAC__ASSERT(0 != reference);
 615         FLAC__ASSERT(0 != gain);
 616         FLAC__ASSERT(0 != peak);
 617         FLAC__ASSERT(block->type == FLAC__METADATA_TYPE_VORBIS_COMMENT);
 618
 619         /* Default to current level until overridden by a detected tag; this
 620          * will always be true until we change replaygain_analysis.c
 621          */
 622         *reference = ReplayGainReferenceLoudness;
 623
 624         /*
 625          * We need to save the old locale and switch to "C" because the locale
 626          * influences the behaviour of strtod and we want it a certain way.
 627          */
 628         saved_locale = strdup(setlocale(LC_ALL, 0));
 629         if (0 == saved_locale)
 630                 return false;
 631         setlocale(LC_ALL, "C");
 632
 633         if(0 <= (reference_offset = FLAC__metadata_object_vorbiscomment_find_entry_from(block, /*offset=*/0, (const char *)GRABBAG__REPLAYGAIN_TAG_REFERENCE_LOUDNESS)))
 634                 (void)parse_double_(block->data.vorbis_comment.comments + reference_offset, reference);
 635
 636         if(0 > (gain_offset = FLAC__metadata_object_vorbiscomment_find_entry_from(block, /*offset=*/0, (const char *)(album_mode? GRABBAG__REPLAYGAIN_TAG_ALBUM_GAIN : GRABBAG__REPLAYGAIN_TAG_TITLE_GAIN))))
 637                 res = false;
 638         if(0 > (peak_offset = FLAC__metadata_object_vorbiscomment_find_entry_from(block, /*offset=*/0, (const char *)(album_mode? GRABBAG__REPLAYGAIN_TAG_ALBUM_PEAK : GRABBAG__REPLAYGAIN_TAG_TITLE_PEAK))))
 639                 res = false;
 640
 641         if(res && !parse_double_(block->data.vorbis_comment.comments + gain_offset, gain))
 642                 res = false;
 643         if(res && !parse_double_(block->data.vorbis_comment.comments + peak_offset, peak))
 644                 res = false;
 645
 646         setlocale(LC_ALL, saved_locale);
 647         free(saved_locale);
 648
 649         /* something failed; retry with strict */
 650         if (!res && !strict)
 651                 res = grabbag__replaygain_load_from_vorbiscomment(block, !album_mode, /*strict=*/true, reference, gain, peak);
 652
 653         return res;
 654 }
 655
 656 double grabbag__replaygain_compute_scale_factor(double peak, double gain, double preamp, FLAC__bool prevent_clipping)
 657 {
 658         double scale;
 659         FLAC__ASSERT(peak >= 0.0);
 660         gain += preamp;
 661         scale = (float) pow(10.0, gain * 0.05);
 662         if(prevent_clipping && peak > 0.0) {
 663                 const double max_scale = (float)(1.0 / peak);
 664                 if(scale > max_scale)
 665                         scale = max_scale;
 666         }
 667         return scale;
 668 }