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  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         static const unsigned valid_sample_rates[] = {
 122                 8000,
 123                 11025,
 124                 12000,
 125                 16000,
 126                 22050,
 127                 24000,
 128                 32000,
 129                 44100,
 130                 48000
 131         };
 132         static const unsigned n_valid_sample_rates = sizeof(valid_sample_rates) / sizeof(valid_sample_rates[0]);
 133
 134         unsigned i;
 135
 136         for(i = 0; i < n_valid_sample_rates; i++)
 137                 if(sample_frequency == valid_sample_rates[i])
 138                         return true;
 139         return false;
 140 }
 141
 142 FLAC__bool grabbag__replaygain_init(unsigned sample_frequency)
 143 {
 144         title_peak_ = album_peak_ = 0.0;
 145         return InitGainAnalysis((long)sample_frequency) == INIT_GAIN_ANALYSIS_OK;
 146 }
 147
 148 FLAC__bool grabbag__replaygain_analyze(const FLAC__int32 * const input[], FLAC__bool is_stereo, unsigned bps, unsigned samples)
 149 {
 150         /* using a small buffer improves data locality; we'd like it to fit easily in the dcache */
 151         static Float_t lbuffer[2048], rbuffer[2048];
 152         static const unsigned nbuffer = sizeof(lbuffer) / sizeof(lbuffer[0]);
 153         FLAC__int32 block_peak = 0, s;
 154         unsigned i, j;
 155
 156         FLAC__ASSERT(bps >= 4 && bps <= FLAC__REFERENCE_CODEC_MAX_BITS_PER_SAMPLE);
 157         FLAC__ASSERT(FLAC__MIN_BITS_PER_SAMPLE == 4);
 158         /*
 159          * We use abs() on a FLAC__int32 which is undefined for the most negative value.
 160          * If the reference codec ever handles 32bps we will have to write a special
 161          * case here.
 162          */
 163         FLAC__ASSERT(FLAC__REFERENCE_CODEC_MAX_BITS_PER_SAMPLE < 32);
 164
 165         if(bps == 16) {
 166                 if(is_stereo) {
 167                         j = 0;
 168                         while(samples > 0) {
 169                                 const unsigned n = local_min(samples, nbuffer);
 170                                 for(i = 0; i < n; i++, j++) {
 171                                         s = input[0][j];
 172                                         lbuffer[i] = (Float_t)s;
 173                                         s = abs(s);
 174                                         block_peak = local_max(block_peak, s);
 175
 176                                         s = input[1][j];
 177                                         rbuffer[i] = (Float_t)s;
 178                                         s = abs(s);
 179                                         block_peak = local_max(block_peak, s);
 180                                 }
 181                                 samples -= n;
 182                                 if(AnalyzeSamples(lbuffer, rbuffer, n, 2) != GAIN_ANALYSIS_OK)
 183                                         return false;
 184                         }
 185                 }
 186                 else {
 187                         j = 0;
 188                         while(samples > 0) {
 189                                 const unsigned n = local_min(samples, nbuffer);
 190                                 for(i = 0; i < n; i++, j++) {
 191                                         s = input[0][j];
 192                                         lbuffer[i] = (Float_t)s;
 193                                         s = abs(s);
 194                                         block_peak = local_max(block_peak, s);
 195                                 }
 196                                 samples -= n;
 197                                 if(AnalyzeSamples(lbuffer, 0, n, 1) != GAIN_ANALYSIS_OK)
 198                                         return false;
 199                         }
 200                 }
 201         }
 202         else { /* bps must be < 32 according to above assertion */
 203                 const double scale = (
 204                         (bps > 16)?
 205                                 (double)1. / (double)(1u << (bps - 16)) :
 206                                 (double)(1u << (16 - bps))
 207                 );
 208
 209                 if(is_stereo) {
 210                         j = 0;
 211                         while(samples > 0) {
 212                                 const unsigned n = local_min(samples, nbuffer);
 213                                 for(i = 0; i < n; i++, j++) {
 214                                         s = input[0][j];
 215                                         lbuffer[i] = (Float_t)(scale * (double)s);
 216                                         s = abs(s);
 217                                         block_peak = local_max(block_peak, s);
 218
 219                                         s = input[1][j];
 220                                         rbuffer[i] = (Float_t)(scale * (double)s);
 221                                         s = abs(s);
 222                                         block_peak = local_max(block_peak, s);
 223                                 }
 224                                 samples -= n;
 225                                 if(AnalyzeSamples(lbuffer, rbuffer, n, 2) != GAIN_ANALYSIS_OK)
 226                                         return false;
 227                         }
 228                 }
 229                 else {
 230                         j = 0;
 231                         while(samples > 0) {
 232                                 const unsigned n = local_min(samples, nbuffer);
 233                                 for(i = 0; i < n; i++, j++) {
 234                                         s = input[0][j];
 235                                         lbuffer[i] = (Float_t)(scale * (double)s);
 236                                         s = abs(s);
 237                                         block_peak = local_max(block_peak, s);
 238                                 }
 239                                 samples -= n;
 240                                 if(AnalyzeSamples(lbuffer, 0, n, 1) != GAIN_ANALYSIS_OK)
 241                                         return false;
 242                         }
 243                 }
 244         }
 245
 246         {
 247                 const double peak_scale = (double)(1u << (bps - 1));
 248                 double peak = (double)block_peak / peak_scale;
 249                 if(peak > title_peak_)
 250                         title_peak_ = peak;
 251                 if(peak > album_peak_)
 252                         album_peak_ = peak;
 253         }
 254
 255         return true;
 256 }
 257
 258 void grabbag__replaygain_get_album(float *gain, float *peak)
 259 {
 260         *gain = (float)GetAlbumGain();
 261         *peak = (float)album_peak_;
 262         album_peak_ = 0.0;
 263 }
 264
 265 void grabbag__replaygain_get_title(float *gain, float *peak)
 266 {
 267         *gain = (float)GetTitleGain();
 268         *peak = (float)title_peak_;
 269         title_peak_ = 0.0;
 270 }
 271
 272
 273 typedef struct {
 274         unsigned channels;
 275         unsigned bits_per_sample;
 276         unsigned sample_rate;
 277         FLAC__bool error;
 278 } DecoderInstance;
 279
 280 static FLAC__StreamDecoderWriteStatus write_callback_(const FLAC__StreamDecoder *decoder, const FLAC__Frame *frame, const FLAC__int32 * const buffer[], void *client_data)
 281 {
 282         DecoderInstance *instance = (DecoderInstance*)client_data;
 283         const unsigned bits_per_sample = frame->header.bits_per_sample;
 284         const unsigned channels = frame->header.channels;
 285         const unsigned sample_rate = frame->header.sample_rate;
 286         const unsigned samples = frame->header.blocksize;
 287
 288         (void)decoder;
 289
 290         if(
 291                 !instance->error &&
 292                 (channels == 2 || channels == 1) &&
 293                 bits_per_sample == instance->bits_per_sample &&
 294                 channels == instance->channels &&
 295                 sample_rate == instance->sample_rate
 296         ) {
 297                 instance->error = !grabbag__replaygain_analyze(buffer, channels==2, bits_per_sample, samples);
 298         }
 299         else {
 300                 instance->error = true;
 301         }
 302
 303         if(!instance->error)
 304                 return FLAC__STREAM_DECODER_WRITE_STATUS_CONTINUE;
 305         else
 306                 return FLAC__STREAM_DECODER_WRITE_STATUS_ABORT;
 307 }
 308
 309 static void metadata_callback_(const FLAC__StreamDecoder *decoder, const FLAC__StreamMetadata *metadata, void *client_data)
 310 {
 311         DecoderInstance *instance = (DecoderInstance*)client_data;
 312
 313         (void)decoder;
 314
 315         if(metadata->type == FLAC__METADATA_TYPE_STREAMINFO) {
 316                 instance->bits_per_sample = metadata->data.stream_info.bits_per_sample;
 317                 instance->channels = metadata->data.stream_info.channels;
 318                 instance->sample_rate = metadata->data.stream_info.sample_rate;
 319
 320                 if(instance->channels != 1 && instance->channels != 2) {
 321                         instance->error = true;
 322                         return;
 323                 }
 324
 325                 if(!grabbag__replaygain_is_valid_sample_frequency(instance->sample_rate)) {
 326                         instance->error = true;
 327                         return;
 328                 }
 329         }
 330 }
 331
 332 static void error_callback_(const FLAC__StreamDecoder *decoder, FLAC__StreamDecoderErrorStatus status, void *client_data)
 333 {
 334         DecoderInstance *instance = (DecoderInstance*)client_data;
 335
 336         (void)decoder, (void)status;
 337
 338         instance->error = true;
 339 }
 340
 341 const char *grabbag__replaygain_analyze_file(const char *filename, float *title_gain, float *title_peak)
 342 {
 343         DecoderInstance instance;
 344         FLAC__StreamDecoder *decoder = FLAC__stream_decoder_new();
 345
 346         if(0 == decoder)
 347                 return "memory allocation error";
 348
 349         instance.error = false;
 350
 351         /* It does these three by default but lets be explicit: */
 352         FLAC__stream_decoder_set_md5_checking(decoder, false);
 353         FLAC__stream_decoder_set_metadata_ignore_all(decoder);
 354         FLAC__stream_decoder_set_metadata_respond(decoder, FLAC__METADATA_TYPE_STREAMINFO);
 355
 356         if(FLAC__stream_decoder_init_file(decoder, filename, write_callback_, metadata_callback_, error_callback_, &instance) != FLAC__STREAM_DECODER_INIT_STATUS_OK) {
 357                 FLAC__stream_decoder_delete(decoder);
 358                 return "initializing decoder";
 359         }
 360
 361         if(!FLAC__stream_decoder_process_until_end_of_stream(decoder) || instance.error) {
 362                 FLAC__stream_decoder_delete(decoder);
 363                 return "decoding file";
 364         }
 365
 366         FLAC__stream_decoder_delete(decoder);
 367
 368         grabbag__replaygain_get_title(title_gain, title_peak);
 369
 370         return 0;
 371 }
 372
 373 const char *grabbag__replaygain_store_to_vorbiscomment(FLAC__StreamMetadata *block, float album_gain, float album_peak, float title_gain, float title_peak)
 374 {
 375         const char *error;
 376
 377         if(0 != (error = grabbag__replaygain_store_to_vorbiscomment_reference(block)))
 378                 return error;
 379
 380         if(0 != (error = grabbag__replaygain_store_to_vorbiscomment_title(block, title_gain, title_peak)))
 381                 return error;
 382
 383         if(0 != (error = grabbag__replaygain_store_to_vorbiscomment_album(block, album_gain, album_peak)))
 384                 return error;
 385
 386         return 0;
 387 }
 388
 389 const char *grabbag__replaygain_store_to_vorbiscomment_reference(FLAC__StreamMetadata *block)
 390 {
 391         FLAC__ASSERT(0 != block);
 392         FLAC__ASSERT(block->type == FLAC__METADATA_TYPE_VORBIS_COMMENT);
 393
 394         if(FLAC__metadata_object_vorbiscomment_remove_entries_matching(block, (const char *)GRABBAG__REPLAYGAIN_TAG_REFERENCE_LOUDNESS) < 0)
 395                 return "memory allocation error";
 396
 397         if(!append_tag_(block, reference_format_, GRABBAG__REPLAYGAIN_TAG_REFERENCE_LOUDNESS, ReplayGainReferenceLoudness))
 398                 return "memory allocation error";
 399
 400         return 0;
 401 }
 402
 403 const char *grabbag__replaygain_store_to_vorbiscomment_album(FLAC__StreamMetadata *block, float album_gain, float album_peak)
 404 {
 405         FLAC__ASSERT(0 != block);
 406         FLAC__ASSERT(block->type == FLAC__METADATA_TYPE_VORBIS_COMMENT);
 407
 408         if(
 409                 FLAC__metadata_object_vorbiscomment_remove_entries_matching(block, (const char *)GRABBAG__REPLAYGAIN_TAG_ALBUM_GAIN) < 0 ||
 410                 FLAC__metadata_object_vorbiscomment_remove_entries_matching(block, (const char *)GRABBAG__REPLAYGAIN_TAG_ALBUM_PEAK) < 0
 411         )
 412                 return "memory allocation error";
 413
 414         if(
 415                 !append_tag_(block, gain_format_, GRABBAG__REPLAYGAIN_TAG_ALBUM_GAIN, album_gain) ||
 416                 !append_tag_(block, peak_format_, GRABBAG__REPLAYGAIN_TAG_ALBUM_PEAK, album_peak)
 417         )
 418                 return "memory allocation error";
 419
 420         return 0;
 421 }
 422
 423 const char *grabbag__replaygain_store_to_vorbiscomment_title(FLAC__StreamMetadata *block, float title_gain, float title_peak)
 424 {
 425         FLAC__ASSERT(0 != block);
 426         FLAC__ASSERT(block->type == FLAC__METADATA_TYPE_VORBIS_COMMENT);
 427
 428         if(
 429                 FLAC__metadata_object_vorbiscomment_remove_entries_matching(block, (const char *)GRABBAG__REPLAYGAIN_TAG_TITLE_GAIN) < 0 ||
 430                 FLAC__metadata_object_vorbiscomment_remove_entries_matching(block, (const char *)GRABBAG__REPLAYGAIN_TAG_TITLE_PEAK) < 0
 431         )
 432                 return "memory allocation error";
 433
 434         if(
 435                 !append_tag_(block, gain_format_, GRABBAG__REPLAYGAIN_TAG_TITLE_GAIN, title_gain) ||
 436                 !append_tag_(block, peak_format_, GRABBAG__REPLAYGAIN_TAG_TITLE_PEAK, title_peak)
 437         )
 438                 return "memory allocation error";
 439
 440         return 0;
 441 }
 442
 443 static const char *store_to_file_pre_(const char *filename, FLAC__Metadata_Chain **chain, FLAC__StreamMetadata **block)
 444 {
 445         FLAC__Metadata_Iterator *iterator;
 446         const char *error;
 447         FLAC__bool found_vc_block = false;
 448
 449         if(0 == (*chain = FLAC__metadata_chain_new()))
 450                 return "memory allocation error";
 451
 452         if(!FLAC__metadata_chain_read(*chain, filename)) {
 453                 error = FLAC__Metadata_ChainStatusString[FLAC__metadata_chain_status(*chain)];
 454                 FLAC__metadata_chain_delete(*chain);
 455                 return error;
 456         }
 457
 458         if(0 == (iterator = FLAC__metadata_iterator_new())) {
 459                 FLAC__metadata_chain_delete(*chain);
 460                 return "memory allocation error";
 461         }
 462
 463         FLAC__metadata_iterator_init(iterator, *chain);
 464
 465         do {
 466                 *block = FLAC__metadata_iterator_get_block(iterator);
 467                 if((*block)->type == FLAC__METADATA_TYPE_VORBIS_COMMENT)
 468                         found_vc_block = true;
 469         } while(!found_vc_block && FLAC__metadata_iterator_next(iterator));
 470
 471         if(!found_vc_block) {
 472                 /* create a new block */
 473                 *block = FLAC__metadata_object_new(FLAC__METADATA_TYPE_VORBIS_COMMENT);
 474                 if(0 == *block) {
 475                         FLAC__metadata_chain_delete(*chain);
 476                         FLAC__metadata_iterator_delete(iterator);
 477                         return "memory allocation error";
 478                 }
 479                 while(FLAC__metadata_iterator_next(iterator))
 480                         ;
 481                 if(!FLAC__metadata_iterator_insert_block_after(iterator, *block)) {
 482                         error = FLAC__Metadata_ChainStatusString[FLAC__metadata_chain_status(*chain)];
 483                         FLAC__metadata_chain_delete(*chain);
 484                         FLAC__metadata_iterator_delete(iterator);
 485                         return error;
 486                 }
 487                 /* iterator is left pointing to new block */
 488                 FLAC__ASSERT(FLAC__metadata_iterator_get_block(iterator) == *block);
 489         }
 490
 491         FLAC__metadata_iterator_delete(iterator);
 492
 493         FLAC__ASSERT(0 != *block);
 494         FLAC__ASSERT((*block)->type == FLAC__METADATA_TYPE_VORBIS_COMMENT);
 495
 496         return 0;
 497 }
 498
 499 static const char *store_to_file_post_(const char *filename, FLAC__Metadata_Chain *chain, FLAC__bool preserve_modtime)
 500 {
 501         struct stat stats;
 502         const FLAC__bool have_stats = get_file_stats_(filename, &stats);
 503
 504         (void)grabbag__file_change_stats(filename, /*read_only=*/false);
 505
 506         FLAC__metadata_chain_sort_padding(chain);
 507         if(!FLAC__metadata_chain_write(chain, /*use_padding=*/true, preserve_modtime)) {
 508                 FLAC__metadata_chain_delete(chain);
 509                 return FLAC__Metadata_ChainStatusString[FLAC__metadata_chain_status(chain)];
 510         }
 511
 512         FLAC__metadata_chain_delete(chain);
 513
 514         if(have_stats)
 515                 set_file_stats_(filename, &stats);
 516
 517         return 0;
 518 }
 519
 520 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)
 521 {
 522         FLAC__Metadata_Chain *chain;
 523         FLAC__StreamMetadata *block;
 524         const char *error;
 525
 526         if(0 != (error = store_to_file_pre_(filename, &chain, &block)))
 527                 return error;
 528
 529         if(0 != (error = grabbag__replaygain_store_to_vorbiscomment(block, album_gain, album_peak, title_gain, title_peak))) {
 530                 FLAC__metadata_chain_delete(chain);
 531                 return error;
 532         }
 533
 534         if(0 != (error = store_to_file_post_(filename, chain, preserve_modtime)))
 535                 return error;
 536
 537         return 0;
 538 }
 539
 540 const char *grabbag__replaygain_store_to_file_reference(const char *filename, FLAC__bool preserve_modtime)
 541 {
 542         FLAC__Metadata_Chain *chain;
 543         FLAC__StreamMetadata *block;
 544         const char *error;
 545
 546         if(0 != (error = store_to_file_pre_(filename, &chain, &block)))
 547                 return error;
 548
 549         if(0 != (error = grabbag__replaygain_store_to_vorbiscomment_reference(block))) {
 550                 FLAC__metadata_chain_delete(chain);
 551                 return error;
 552         }
 553
 554         if(0 != (error = store_to_file_post_(filename, chain, preserve_modtime)))
 555                 return error;
 556
 557         return 0;
 558 }
 559
 560 const char *grabbag__replaygain_store_to_file_album(const char *filename, float album_gain, float album_peak, FLAC__bool preserve_modtime)
 561 {
 562         FLAC__Metadata_Chain *chain;
 563         FLAC__StreamMetadata *block;
 564         const char *error;
 565
 566         if(0 != (error = store_to_file_pre_(filename, &chain, &block)))
 567                 return error;
 568
 569         if(0 != (error = grabbag__replaygain_store_to_vorbiscomment_album(block, album_gain, album_peak))) {
 570                 FLAC__metadata_chain_delete(chain);
 571                 return error;
 572         }
 573
 574         if(0 != (error = store_to_file_post_(filename, chain, preserve_modtime)))
 575                 return error;
 576
 577         return 0;
 578 }
 579
 580 const char *grabbag__replaygain_store_to_file_title(const char *filename, float title_gain, float title_peak, FLAC__bool preserve_modtime)
 581 {
 582         FLAC__Metadata_Chain *chain;
 583         FLAC__StreamMetadata *block;
 584         const char *error;
 585
 586         if(0 != (error = store_to_file_pre_(filename, &chain, &block)))
 587                 return error;
 588
 589         if(0 != (error = grabbag__replaygain_store_to_vorbiscomment_title(block, title_gain, title_peak))) {
 590                 FLAC__metadata_chain_delete(chain);
 591                 return error;
 592         }
 593
 594         if(0 != (error = store_to_file_post_(filename, chain, preserve_modtime)))
 595                 return error;
 596
 597         return 0;
 598 }
 599
 600 static FLAC__bool parse_double_(const FLAC__StreamMetadata_VorbisComment_Entry *entry, double *val)
 601 {
 602         char s[32], *end;
 603         const char *p, *q;
 604         double v;
 605
 606         FLAC__ASSERT(0 != entry);
 607         FLAC__ASSERT(0 != val);
 608
 609         p = (const char *)entry->entry;
 610         q = strchr(p, '=');
 611         if(0 == q)
 612                 return false;
 613         q++;
 614         memset(s, 0, sizeof(s)-1);
 615         strncpy(s, q, local_min(sizeof(s)-1, entry->length - (q-p)));
 616
 617         v = strtod(s, &end);
 618         if(end == s)
 619                 return false;
 620
 621         *val = v;
 622         return true;
 623 }
 624
 625 FLAC__bool grabbag__replaygain_load_from_vorbiscomment(const FLAC__StreamMetadata *block, FLAC__bool album_mode, FLAC__bool strict, double *reference, double *gain, double *peak)
 626 {
 627         int reference_offset, gain_offset, peak_offset;
 628
 629         FLAC__ASSERT(0 != block);
 630         FLAC__ASSERT(0 != reference);
 631         FLAC__ASSERT(0 != gain);
 632         FLAC__ASSERT(0 != peak);
 633         FLAC__ASSERT(block->type == FLAC__METADATA_TYPE_VORBIS_COMMENT);
 634
 635         /* Default to current level until overridden by a detected tag; this
 636          * will always be true until we change replaygain_analysis.c
 637          */
 638         *reference = ReplayGainReferenceLoudness;
 639
 640         if(0 <= (reference_offset = FLAC__metadata_object_vorbiscomment_find_entry_from(block, /*offset=*/0, (const char *)GRABBAG__REPLAYGAIN_TAG_REFERENCE_LOUDNESS)))
 641                 (void)parse_double_(block->data.vorbis_comment.comments + reference_offset, reference);
 642
 643         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))))
 644                 return !strict && grabbag__replaygain_load_from_vorbiscomment(block, !album_mode, /*strict=*/true, reference, gain, peak);
 645         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))))
 646                 return !strict && grabbag__replaygain_load_from_vorbiscomment(block, !album_mode, /*strict=*/true, reference, gain, peak);
 647
 648         if(!parse_double_(block->data.vorbis_comment.comments + gain_offset, gain))
 649                 return !strict && grabbag__replaygain_load_from_vorbiscomment(block, !album_mode, /*strict=*/true, reference, gain, peak);
 650         if(!parse_double_(block->data.vorbis_comment.comments + peak_offset, peak))
 651                 return !strict && grabbag__replaygain_load_from_vorbiscomment(block, !album_mode, /*strict=*/true, reference, gain, peak);
 652
 653         return true;
 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 }