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