src/share/grabbag/replaygain.c

   1 /* grabbag - Convenience lib for various routines common to several tools
   2  * Copyright (C) 2002,2003,2004,2005,2006,2007,2008,2009  Josh Coalson
   3  *
   4  * This library is free software; you can redistribute it and/or
   5  * modify it under the terms of the GNU Lesser General Public
   6  * License as published by the Free Software Foundation; either
   7  * version 2.1 of the License, or (at your option) any later version.
   8  *
   9  * This library is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12  * Lesser General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU Lesser General Public
  15  * License along with this library; if not, write to the Free Software
  16  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
  17  */
  18
  19 #if HAVE_CONFIG_H
  20 #  include <config.h>
  21 #endif
  22
  23 #include "share/grabbag.h"
  24 #include "share/replaygain_analysis.h"
  25 #include "FLAC/assert.h"
  26 #include "FLAC/metadata.h"
  27 #include "FLAC/stream_decoder.h"
  28 #include <locale.h>
  29 #include <math.h>
  30 #include <stdio.h>
  31 #include <stdlib.h>
  32 #include <string.h>
  33 #if defined _MSC_VER || defined __MINGW32__
  34 #include <io.h> /* for chmod() */
  35 #endif
  36 #include <sys/stat.h> /* for stat(), maybe chmod() */
  37
  38 #ifdef local_min
  39 #undef local_min
  40 #endif
  41 #define local_min(a,b) ((a)<(b)?(a):(b))
  42
  43 #ifdef local_max
  44 #undef local_max
  45 #endif
  46 #define local_max(a,b) ((a)>(b)?(a):(b))
  47
  48 static const char *reference_format_ = "%s=%2.1f dB";
  49 static const char *gain_format_ = "%s=%+2.2f dB";
  50 static const char *peak_format_ = "%s=%1.8f";
  51
  52 static double album_peak_, title_peak_;
  53
  54 const unsigned GRABBAG__REPLAYGAIN_MAX_TAG_SPACE_REQUIRED = 190;
  55 /*
  56         FLAC__STREAM_METADATA_VORBIS_COMMENT_ENTRY_LENGTH_LEN/8 + 29 + 1 + 8 +
  57         FLAC__STREAM_METADATA_VORBIS_COMMENT_ENTRY_LENGTH_LEN/8 + 21 + 1 + 10 +
  58         FLAC__STREAM_METADATA_VORBIS_COMMENT_ENTRY_LENGTH_LEN/8 + 21 + 1 + 12 +
  59         FLAC__STREAM_METADATA_VORBIS_COMMENT_ENTRY_LENGTH_LEN/8 + 21 + 1 + 10 +
  60         FLAC__STREAM_METADATA_VORBIS_COMMENT_ENTRY_LENGTH_LEN/8 + 21 + 1 + 12
  61 */
  62
  63 const FLAC__byte * const GRABBAG__REPLAYGAIN_TAG_REFERENCE_LOUDNESS = (const FLAC__byte * const)"REPLAYGAIN_REFERENCE_LOUDNESS";
  64 const FLAC__byte * const GRABBAG__REPLAYGAIN_TAG_TITLE_GAIN = (const FLAC__byte * const)"REPLAYGAIN_TRACK_GAIN";
  65 const FLAC__byte * const GRABBAG__REPLAYGAIN_TAG_TITLE_PEAK = (const FLAC__byte * const)"REPLAYGAIN_TRACK_PEAK";
  66 const FLAC__byte * const GRABBAG__REPLAYGAIN_TAG_ALBUM_GAIN = (const FLAC__byte * const)"REPLAYGAIN_ALBUM_GAIN";
  67 const FLAC__byte * const GRABBAG__REPLAYGAIN_TAG_ALBUM_PEAK = (const FLAC__byte * const)"REPLAYGAIN_ALBUM_PEAK";
  68
  69
  70 static FLAC__bool get_file_stats_(const char *filename, struct stat *stats)
  71 {
  72         FLAC__ASSERT(0 != filename);
  73         FLAC__ASSERT(0 != stats);
  74         return (0 == stat(filename, stats));
  75 }
  76
  77 static void set_file_stats_(const char *filename, struct stat *stats)
  78 {
  79         FLAC__ASSERT(0 != filename);
  80         FLAC__ASSERT(0 != stats);
  81
  82         (void)chmod(filename, stats->st_mode);
  83 }
  84
  85 static FLAC__bool append_tag_(FLAC__StreamMetadata *block, const char *format, const FLAC__byte *name, float value)
  86 {
  87         char buffer[256];
  88         char *saved_locale;
  89         FLAC__StreamMetadata_VorbisComment_Entry entry;
  90
  91         FLAC__ASSERT(0 != block);
  92         FLAC__ASSERT(block->type == FLAC__METADATA_TYPE_VORBIS_COMMENT);
  93         FLAC__ASSERT(0 != format);
  94         FLAC__ASSERT(0 != name);
  95
  96         buffer[sizeof(buffer)-1] = '\0';
  97         /*
  98          * We need to save the old locale and switch to "C" because the locale
  99          * influences the formatting of %f and we want it a certain way.
 100          */
 101         saved_locale = strdup(setlocale(LC_ALL, 0));
 102         if (0 == saved_locale)
 103                 return false;
 104         setlocale(LC_ALL, "C");
 105 #if defined _MSC_VER || defined __MINGW32__
 106         _snprintf(buffer, sizeof(buffer)-1, format, name, value);
 107 #else
 108         snprintf(buffer, sizeof(buffer)-1, format, name, value);
 109 #endif
 110         setlocale(LC_ALL, saved_locale);
 111         free(saved_locale);
 112
 113         entry.entry = (FLAC__byte *)buffer;
 114         entry.length = strlen(buffer);
 115
 116         return FLAC__metadata_object_vorbiscomment_append_comment(block, entry, /*copy=*/true);
 117 }
 118
 119 FLAC__bool grabbag__replaygain_is_valid_sample_frequency(unsigned sample_frequency)
 120 {
 121         return ValidGainFrequency( sample_frequency );
 122 }
 123
 124 FLAC__bool grabbag__replaygain_init(unsigned sample_frequency)
 125 {
 126         title_peak_ = album_peak_ = 0.0;
 127         return InitGainAnalysis((long)sample_frequency) == INIT_GAIN_ANALYSIS_OK;
 128 }
 129
 130 FLAC__bool grabbag__replaygain_analyze(const FLAC__int32 * const input[], FLAC__bool is_stereo, unsigned bps, unsigned samples)
 131 {
 132         /* using a small buffer improves data locality; we'd like it to fit easily in the dcache */
 133         static Float_t lbuffer[2048], rbuffer[2048];
 134         static const unsigned nbuffer = sizeof(lbuffer) / sizeof(lbuffer[0]);
 135         FLAC__int32 block_peak = 0, s;
 136         unsigned i, j;
 137
 138         FLAC__ASSERT(bps >= 4 && bps <= FLAC__REFERENCE_CODEC_MAX_BITS_PER_SAMPLE);
 139         FLAC__ASSERT(FLAC__MIN_BITS_PER_SAMPLE == 4);
 140         /*
 141          * We use abs() on a FLAC__int32 which is undefined for the most negative value.
 142          * If the reference codec ever handles 32bps we will have to write a special
 143          * case here.
 144          */
 145         FLAC__ASSERT(FLAC__REFERENCE_CODEC_MAX_BITS_PER_SAMPLE < 32);
 146
 147         if(bps == 16) {
 148                 if(is_stereo) {
 149                         j = 0;
 150                         while(samples > 0) {
 151                                 const unsigned n = local_min(samples, nbuffer);
 152                                 for(i = 0; i < n; i++, j++) {
 153                                         s = input[0][j];
 154                                         lbuffer[i] = (Float_t)s;
 155                                         s = abs(s);
 156                                         block_peak = local_max(block_peak, s);
 157
 158                                         s = input[1][j];
 159                                         rbuffer[i] = (Float_t)s;
 160                                         s = abs(s);
 161                                         block_peak = local_max(block_peak, s);
 162                                 }
 163                                 samples -= n;
 164                                 if(AnalyzeSamples(lbuffer, rbuffer, n, 2) != GAIN_ANALYSIS_OK)
 165                                         return false;
 166                         }
 167                 }
 168                 else {
 169                         j = 0;
 170                         while(samples > 0) {
 171                                 const unsigned n = local_min(samples, nbuffer);
 172                                 for(i = 0; i < n; i++, j++) {
 173                                         s = input[0][j];
 174                                         lbuffer[i] = (Float_t)s;
 175                                         s = abs(s);
 176                                         block_peak = local_max(block_peak, s);
 177                                 }
 178                                 samples -= n;
 179                                 if(AnalyzeSamples(lbuffer, 0, n, 1) != GAIN_ANALYSIS_OK)
 180                                         return false;
 181                         }
 182                 }
 183         }
 184         else { /* bps must be < 32 according to above assertion */
 185                 const double scale = (
 186                         (bps > 16)?
 187                                 (double)1. / (double)(1u << (bps - 16)) :
 188                                 (double)(1u << (16 - bps))
 189                 );
 190
 191                 if(is_stereo) {
 192                         j = 0;
 193                         while(samples > 0) {
 194                                 const unsigned n = local_min(samples, nbuffer);
 195                                 for(i = 0; i < n; i++, j++) {
 196                                         s = input[0][j];
 197                                         lbuffer[i] = (Float_t)(scale * (double)s);
 198                                         s = abs(s);
 199                                         block_peak = local_max(block_peak, s);
 200
 201                                         s = input[1][j];
 202                                         rbuffer[i] = (Float_t)(scale * (double)s);
 203                                         s = abs(s);
 204                                         block_peak = local_max(block_peak, s);
 205                                 }
 206                                 samples -= n;
 207                                 if(AnalyzeSamples(lbuffer, rbuffer, n, 2) != GAIN_ANALYSIS_OK)
 208                                         return false;
 209                         }
 210                 }
 211                 else {
 212                         j = 0;
 213                         while(samples > 0) {
 214                                 const unsigned n = local_min(samples, nbuffer);
 215                                 for(i = 0; i < n; i++, j++) {
 216                                         s = input[0][j];
 217                                         lbuffer[i] = (Float_t)(scale * (double)s);
 218                                         s = abs(s);
 219                                         block_peak = local_max(block_peak, s);
 220                                 }
 221                                 samples -= n;
 222                                 if(AnalyzeSamples(lbuffer, 0, n, 1) != GAIN_ANALYSIS_OK)
 223                                         return false;
 224                         }
 225                 }
 226         }
 227
 228         {
 229                 const double peak_scale = (double)(1u << (bps - 1));
 230                 double peak = (double)block_peak / peak_scale;
 231                 if(peak > title_peak_)
 232                         title_peak_ = peak;
 233                 if(peak > album_peak_)
 234                         album_peak_ = peak;
 235         }
 236
 237         return true;
 238 }
 239
 240 void grabbag__replaygain_get_album(float *gain, float *peak)
 241 {
 242         *gain = (float)GetAlbumGain();
 243         *peak = (float)album_peak_;
 244         album_peak_ = 0.0;
 245 }
 246
 247 void grabbag__replaygain_get_title(float *gain, float *peak)
 248 {
 249         *gain = (float)GetTitleGain();
 250         *peak = (float)title_peak_;
 251         title_peak_ = 0.0;
 252 }
 253
 254
 255 typedef struct {
 256         unsigned channels;
 257         unsigned bits_per_sample;
 258         unsigned sample_rate;
 259         FLAC__bool error;
 260 } DecoderInstance;
 261
 262 static FLAC__StreamDecoderWriteStatus write_callback_(const FLAC__StreamDecoder *decoder, const FLAC__Frame *frame, const FLAC__int32 * const buffer[], void *client_data)
 263 {
 264         DecoderInstance *instance = (DecoderInstance*)client_data;
 265         const unsigned bits_per_sample = frame->header.bits_per_sample;
 266         const unsigned channels = frame->header.channels;
 267         const unsigned sample_rate = frame->header.sample_rate;
 268         const unsigned samples = frame->header.blocksize;
 269
 270         (void)decoder;
 271
 272         if(
 273                 !instance->error &&
 274                 (channels == 2 || channels == 1) &&
 275                 bits_per_sample == instance->bits_per_sample &&
 276                 channels == instance->channels &&
 277                 sample_rate == instance->sample_rate
 278         ) {
 279                 instance->error = !grabbag__replaygain_analyze(buffer, channels==2, bits_per_sample, samples);
 280         }
 281         else {
 282                 instance->error = true;
 283         }
 284
 285         if(!instance->error)
 286                 return FLAC__STREAM_DECODER_WRITE_STATUS_CONTINUE;
 287         else
 288                 return FLAC__STREAM_DECODER_WRITE_STATUS_ABORT;
 289 }
 290
 291 static void metadata_callback_(const FLAC__StreamDecoder *decoder, const FLAC__StreamMetadata *metadata, void *client_data)
 292 {
 293         DecoderInstance *instance = (DecoderInstance*)client_data;
 294
 295         (void)decoder;
 296
 297         if(metadata->type == FLAC__METADATA_TYPE_STREAMINFO) {
 298                 instance->bits_per_sample = metadata->data.stream_info.bits_per_sample;
 299                 instance->channels = metadata->data.stream_info.channels;
 300                 instance->sample_rate = metadata->data.stream_info.sample_rate;
 301
 302                 if(instance->channels != 1 && instance->channels != 2) {
 303                         instance->error = true;
 304                         return;
 305                 }
 306
 307                 if(!grabbag__replaygain_is_valid_sample_frequency(instance->sample_rate)) {
 308                         instance->error = true;
 309                         return;
 310                 }
 311         }
 312 }
 313
 314 static void error_callback_(const FLAC__StreamDecoder *decoder, FLAC__StreamDecoderErrorStatus status, void *client_data)
 315 {
 316         DecoderInstance *instance = (DecoderInstance*)client_data;
 317
 318         (void)decoder, (void)status;
 319
 320         instance->error = true;
 321 }
 322
 323 const char *grabbag__replaygain_analyze_file(const char *filename, float *title_gain, float *title_peak)
 324 {
 325         DecoderInstance instance;
 326         FLAC__StreamDecoder *decoder = FLAC__stream_decoder_new();
 327
 328         if(0 == decoder)
 329                 return "memory allocation error";
 330
 331         instance.error = false;
 332
 333         /* It does these three by default but lets be explicit: */
 334         FLAC__stream_decoder_set_md5_checking(decoder, false);
 335         FLAC__stream_decoder_set_metadata_ignore_all(decoder);
 336         FLAC__stream_decoder_set_metadata_respond(decoder, FLAC__METADATA_TYPE_STREAMINFO);
 337
 338         if(FLAC__stream_decoder_init_file(decoder, filename, write_callback_, metadata_callback_, error_callback_, &instance) != FLAC__STREAM_DECODER_INIT_STATUS_OK) {
 339                 FLAC__stream_decoder_delete(decoder);
 340                 return "initializing decoder";
 341         }
 342
 343         if(!FLAC__stream_decoder_process_until_end_of_stream(decoder) || instance.error) {
 344                 FLAC__stream_decoder_delete(decoder);
 345                 return "decoding file";
 346         }
 347
 348         FLAC__stream_decoder_delete(decoder);
 349
 350         grabbag__replaygain_get_title(title_gain, title_peak);
 351
 352         return 0;
 353 }
 354
 355 const char *grabbag__replaygain_store_to_vorbiscomment(FLAC__StreamMetadata *block, float album_gain, float album_peak, float title_gain, float title_peak)
 356 {
 357         const char *error;
 358
 359         if(0 != (error = grabbag__replaygain_store_to_vorbiscomment_reference(block)))
 360                 return error;
 361
 362         if(0 != (error = grabbag__replaygain_store_to_vorbiscomment_title(block, title_gain, title_peak)))
 363                 return error;
 364
 365         if(0 != (error = grabbag__replaygain_store_to_vorbiscomment_album(block, album_gain, album_peak)))
 366                 return error;
 367
 368         return 0;
 369 }
 370
 371 const char *grabbag__replaygain_store_to_vorbiscomment_reference(FLAC__StreamMetadata *block)
 372 {
 373         FLAC__ASSERT(0 != block);
 374         FLAC__ASSERT(block->type == FLAC__METADATA_TYPE_VORBIS_COMMENT);
 375
 376         if(FLAC__metadata_object_vorbiscomment_remove_entries_matching(block, (const char *)GRABBAG__REPLAYGAIN_TAG_REFERENCE_LOUDNESS) < 0)
 377                 return "memory allocation error";
 378
 379         if(!append_tag_(block, reference_format_, GRABBAG__REPLAYGAIN_TAG_REFERENCE_LOUDNESS, ReplayGainReferenceLoudness))
 380                 return "memory allocation error";
 381
 382         return 0;
 383 }
 384
 385 const char *grabbag__replaygain_store_to_vorbiscomment_album(FLAC__StreamMetadata *block, float album_gain, float album_peak)
 386 {
 387         FLAC__ASSERT(0 != block);
 388         FLAC__ASSERT(block->type == FLAC__METADATA_TYPE_VORBIS_COMMENT);
 389
 390         if(
 391                 FLAC__metadata_object_vorbiscomment_remove_entries_matching(block, (const char *)GRABBAG__REPLAYGAIN_TAG_ALBUM_GAIN) < 0 ||
 392                 FLAC__metadata_object_vorbiscomment_remove_entries_matching(block, (const char *)GRABBAG__REPLAYGAIN_TAG_ALBUM_PEAK) < 0
 393         )
 394                 return "memory allocation error";
 395
 396         if(
 397                 !append_tag_(block, gain_format_, GRABBAG__REPLAYGAIN_TAG_ALBUM_GAIN, album_gain) ||
 398                 !append_tag_(block, peak_format_, GRABBAG__REPLAYGAIN_TAG_ALBUM_PEAK, album_peak)
 399         )
 400                 return "memory allocation error";
 401
 402         return 0;
 403 }
 404
 405 const char *grabbag__replaygain_store_to_vorbiscomment_title(FLAC__StreamMetadata *block, float title_gain, float title_peak)
 406 {
 407         FLAC__ASSERT(0 != block);
 408         FLAC__ASSERT(block->type == FLAC__METADATA_TYPE_VORBIS_COMMENT);
 409
 410         if(
 411                 FLAC__metadata_object_vorbiscomment_remove_entries_matching(block, (const char *)GRABBAG__REPLAYGAIN_TAG_TITLE_GAIN) < 0 ||
 412                 FLAC__metadata_object_vorbiscomment_remove_entries_matching(block, (const char *)GRABBAG__REPLAYGAIN_TAG_TITLE_PEAK) < 0
 413         )
 414                 return "memory allocation error";
 415
 416         if(
 417                 !append_tag_(block, gain_format_, GRABBAG__REPLAYGAIN_TAG_TITLE_GAIN, title_gain) ||
 418                 !append_tag_(block, peak_format_, GRABBAG__REPLAYGAIN_TAG_TITLE_PEAK, title_peak)
 419         )
 420                 return "memory allocation error";
 421
 422         return 0;
 423 }
 424
 425 static const char *store_to_file_pre_(const char *filename, FLAC__Metadata_Chain **chain, FLAC__StreamMetadata **block)
 426 {
 427         FLAC__Metadata_Iterator *iterator;
 428         const char *error;
 429         FLAC__bool found_vc_block = false;
 430
 431         if(0 == (*chain = FLAC__metadata_chain_new()))
 432                 return "memory allocation error";
 433
 434         if(!FLAC__metadata_chain_read(*chain, filename)) {
 435                 error = FLAC__Metadata_ChainStatusString[FLAC__metadata_chain_status(*chain)];
 436                 FLAC__metadata_chain_delete(*chain);
 437                 return error;
 438         }
 439
 440         if(0 == (iterator = FLAC__metadata_iterator_new())) {
 441                 FLAC__metadata_chain_delete(*chain);
 442                 return "memory allocation error";
 443         }
 444
 445         FLAC__metadata_iterator_init(iterator, *chain);
 446
 447         do {
 448                 *block = FLAC__metadata_iterator_get_block(iterator);
 449                 if((*block)->type == FLAC__METADATA_TYPE_VORBIS_COMMENT)
 450                         found_vc_block = true;
 451         } while(!found_vc_block && FLAC__metadata_iterator_next(iterator));
 452
 453         if(!found_vc_block) {
 454                 /* create a new block */
 455                 *block = FLAC__metadata_object_new(FLAC__METADATA_TYPE_VORBIS_COMMENT);
 456                 if(0 == *block) {
 457                         FLAC__metadata_chain_delete(*chain);
 458                         FLAC__metadata_iterator_delete(iterator);
 459                         return "memory allocation error";
 460                 }
 461                 while(FLAC__metadata_iterator_next(iterator))
 462                         ;
 463                 if(!FLAC__metadata_iterator_insert_block_after(iterator, *block)) {
 464                         error = FLAC__Metadata_ChainStatusString[FLAC__metadata_chain_status(*chain)];
 465                         FLAC__metadata_chain_delete(*chain);
 466                         FLAC__metadata_iterator_delete(iterator);
 467                         return error;
 468                 }
 469                 /* iterator is left pointing to new block */
 470                 FLAC__ASSERT(FLAC__metadata_iterator_get_block(iterator) == *block);
 471         }
 472
 473         FLAC__metadata_iterator_delete(iterator);
 474
 475         FLAC__ASSERT(0 != *block);
 476         FLAC__ASSERT((*block)->type == FLAC__METADATA_TYPE_VORBIS_COMMENT);
 477
 478         return 0;
 479 }
 480
 481 static const char *store_to_file_post_(const char *filename, FLAC__Metadata_Chain *chain, FLAC__bool preserve_modtime)
 482 {
 483         struct stat stats;
 484         const FLAC__bool have_stats = get_file_stats_(filename, &stats);
 485
 486         (void)grabbag__file_change_stats(filename, /*read_only=*/false);
 487
 488         FLAC__metadata_chain_sort_padding(chain);
 489         if(!FLAC__metadata_chain_write(chain, /*use_padding=*/true, preserve_modtime)) {
 490                 const char *error;
 491                 error = FLAC__Metadata_ChainStatusString[FLAC__metadata_chain_status(chain)];
 492                 FLAC__metadata_chain_delete(chain);
 493                 return error;
 494         }
 495
 496         FLAC__metadata_chain_delete(chain);
 497
 498         if(have_stats)
 499                 set_file_stats_(filename, &stats);
 500
 501         return 0;
 502 }
 503
 504 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)
 505 {
 506         FLAC__Metadata_Chain *chain;
 507         FLAC__StreamMetadata *block;
 508         const char *error;
 509
 510         if(0 != (error = store_to_file_pre_(filename, &chain, &block)))
 511                 return error;
 512
 513         if(0 != (error = grabbag__replaygain_store_to_vorbiscomment(block, album_gain, album_peak, title_gain, title_peak))) {
 514                 FLAC__metadata_chain_delete(chain);
 515                 return error;
 516         }
 517
 518         if(0 != (error = store_to_file_post_(filename, chain, preserve_modtime)))
 519                 return error;
 520
 521         return 0;
 522 }
 523
 524 const char *grabbag__replaygain_store_to_file_reference(const char *filename, FLAC__bool preserve_modtime)
 525 {
 526         FLAC__Metadata_Chain *chain;
 527         FLAC__StreamMetadata *block;
 528         const char *error;
 529
 530         if(0 != (error = store_to_file_pre_(filename, &chain, &block)))
 531                 return error;
 532
 533         if(0 != (error = grabbag__replaygain_store_to_vorbiscomment_reference(block))) {
 534                 FLAC__metadata_chain_delete(chain);
 535                 return error;
 536         }
 537
 538         if(0 != (error = store_to_file_post_(filename, chain, preserve_modtime)))
 539                 return error;
 540
 541         return 0;
 542 }
 543
 544 const char *grabbag__replaygain_store_to_file_album(const char *filename, float album_gain, float album_peak, FLAC__bool preserve_modtime)
 545 {
 546         FLAC__Metadata_Chain *chain;
 547         FLAC__StreamMetadata *block;
 548         const char *error;
 549
 550         if(0 != (error = store_to_file_pre_(filename, &chain, &block)))
 551                 return error;
 552
 553         if(0 != (error = grabbag__replaygain_store_to_vorbiscomment_album(block, album_gain, album_peak))) {
 554                 FLAC__metadata_chain_delete(chain);
 555                 return error;
 556         }
 557
 558         if(0 != (error = store_to_file_post_(filename, chain, preserve_modtime)))
 559                 return error;
 560
 561         return 0;
 562 }
 563
 564 const char *grabbag__replaygain_store_to_file_title(const char *filename, float title_gain, float title_peak, FLAC__bool preserve_modtime)
 565 {
 566         FLAC__Metadata_Chain *chain;
 567         FLAC__StreamMetadata *block;
 568         const char *error;
 569
 570         if(0 != (error = store_to_file_pre_(filename, &chain, &block)))
 571                 return error;
 572
 573         if(0 != (error = grabbag__replaygain_store_to_vorbiscomment_title(block, title_gain, title_peak))) {
 574                 FLAC__metadata_chain_delete(chain);
 575                 return error;
 576         }
 577
 578         if(0 != (error = store_to_file_post_(filename, chain, preserve_modtime)))
 579                 return error;
 580
 581         return 0;
 582 }
 583
 584 static FLAC__bool parse_double_(const FLAC__StreamMetadata_VorbisComment_Entry *entry, double *val)
 585 {
 586         char s[32], *end;
 587         const char *p, *q;
 588         double v;
 589
 590         FLAC__ASSERT(0 != entry);
 591         FLAC__ASSERT(0 != val);
 592
 593         p = (const char *)entry->entry;
 594         q = strchr(p, '=');
 595         if(0 == q)
 596                 return false;
 597         q++;
 598         memset(s, 0, sizeof(s)-1);
 599         strncpy(s, q, local_min(sizeof(s)-1, (size_t) (entry->length - (q-p))));
 600
 601         v = strtod(s, &end);
 602         if(end == s)
 603                 return false;
 604
 605         *val = v;
 606         return true;
 607 }
 608
 609 FLAC__bool grabbag__replaygain_load_from_vorbiscomment(const FLAC__StreamMetadata *block, FLAC__bool album_mode, FLAC__bool strict, double *reference, double *gain, double *peak)
 610 {
 611         int reference_offset, gain_offset, peak_offset;
 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         if(0 <= (reference_offset = FLAC__metadata_object_vorbiscomment_find_entry_from(block, /*offset=*/0, (const char *)GRABBAG__REPLAYGAIN_TAG_REFERENCE_LOUDNESS)))
 625                 (void)parse_double_(block->data.vorbis_comment.comments + reference_offset, reference);
 626
 627         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))))
 628                 return !strict && grabbag__replaygain_load_from_vorbiscomment(block, !album_mode, /*strict=*/true, reference, gain, peak);
 629         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))))
 630                 return !strict && grabbag__replaygain_load_from_vorbiscomment(block, !album_mode, /*strict=*/true, reference, gain, peak);
 631
 632         if(!parse_double_(block->data.vorbis_comment.comments + gain_offset, gain))
 633                 return !strict && grabbag__replaygain_load_from_vorbiscomment(block, !album_mode, /*strict=*/true, reference, gain, peak);
 634         if(!parse_double_(block->data.vorbis_comment.comments + peak_offset, peak))
 635                 return !strict && grabbag__replaygain_load_from_vorbiscomment(block, !album_mode, /*strict=*/true, reference, gain, peak);
 636
 637         return true;
 638 }
 639
 640 double grabbag__replaygain_compute_scale_factor(double peak, double gain, double preamp, FLAC__bool prevent_clipping)
 641 {
 642         double scale;
 643         FLAC__ASSERT(peak >= 0.0);
 644         gain += preamp;
 645         scale = (float) pow(10.0, gain * 0.05);
 646         if(prevent_clipping && peak > 0.0) {
 647                 const double max_scale = (float)(1.0 / peak);
 648                 if(scale > max_scale)
 649                         scale = max_scale;
 650         }
 651         return scale;
 652 }