src/libFLAC/seekable_stream_decoder.c

   1 /* libFLAC - Free Lossless Audio Codec library
   2  * Copyright (C) 2000,2001,2002  Josh Coalson
   3  *
   4  * This library is free software; you can redistribute it and/or
   5  * modify it under the terms of the GNU Library General Public
   6  * License as published by the Free Software Foundation; either
   7  * version 2 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  * Library General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU Library General Public
  15  * License along with this library; if not, write to the
  16  * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  17  * Boston, MA  02111-1307, USA.
  18  */
  19
  20 #include <stdio.h>
  21 #include <stdlib.h> /* for malloc() */
  22 #include <string.h> /* for memcpy()/memcmp() */
  23 #include "FLAC/assert.h"
  24 #include "protected/seekable_stream_decoder.h"
  25 #include "protected/stream_decoder.h"
  26 #include "private/md5.h"
  27
  28 /***********************************************************************
  29  *
  30  * Private class method prototypes
  31  *
  32  ***********************************************************************/
  33
  34 static void seekable_stream_decoder_set_defaults_(FLAC__SeekableStreamDecoder *decoder);
  35 static FLAC__StreamDecoderReadStatus read_callback_(const FLAC__StreamDecoder *decoder, FLAC__byte buffer[], unsigned *bytes, void *client_data);
  36 static FLAC__StreamDecoderWriteStatus write_callback_(const FLAC__StreamDecoder *decoder, const FLAC__Frame *frame, const FLAC__int32 * const buffer[], void *client_data);
  37 static void metadata_callback_(const FLAC__StreamDecoder *decoder, const FLAC__StreamMetadata *metadata, void *client_data);
  38 static void error_callback_(const FLAC__StreamDecoder *decoder, FLAC__StreamDecoderErrorStatus status, void *client_data);
  39 static FLAC__bool seek_to_absolute_sample_(FLAC__SeekableStreamDecoder *decoder, FLAC__uint64 stream_length, FLAC__uint64 target_sample);
  40
  41 /***********************************************************************
  42  *
  43  * Private class data
  44  *
  45  ***********************************************************************/
  46
  47 typedef struct FLAC__SeekableStreamDecoderPrivate {
  48         FLAC__SeekableStreamDecoderReadStatus (*read_callback)(const FLAC__SeekableStreamDecoder *decoder, FLAC__byte buffer[], unsigned *bytes, void *client_data);
  49         FLAC__SeekableStreamDecoderSeekStatus (*seek_callback)(const FLAC__SeekableStreamDecoder *decoder, FLAC__uint64 absolute_byte_offset, void *client_data);
  50         FLAC__SeekableStreamDecoderTellStatus (*tell_callback)(const FLAC__SeekableStreamDecoder *decoder, FLAC__uint64 *absolute_byte_offset, void *client_data);
  51         FLAC__SeekableStreamDecoderLengthStatus (*length_callback)(const FLAC__SeekableStreamDecoder *decoder, FLAC__uint64 *stream_length, void *client_data);
  52         FLAC__bool (*eof_callback)(const FLAC__SeekableStreamDecoder *decoder, void *client_data);
  53         FLAC__StreamDecoderWriteStatus (*write_callback)(const FLAC__SeekableStreamDecoder *decoder, const FLAC__Frame *frame, const FLAC__int32 * const buffer[], void *client_data);
  54         void (*metadata_callback)(const FLAC__SeekableStreamDecoder *decoder, const FLAC__StreamMetadata *metadata, void *client_data);
  55         void (*error_callback)(const FLAC__SeekableStreamDecoder *decoder, FLAC__StreamDecoderErrorStatus status, void *client_data);
  56         void *client_data;
  57         FLAC__StreamDecoder *stream_decoder;
  58         struct MD5Context md5context;
  59         FLAC__byte stored_md5sum[16]; /* this is what is stored in the metadata */
  60         FLAC__byte computed_md5sum[16]; /* this is the sum we computed from the decoded data */
  61         /* the rest of these are only used for seeking: */
  62         FLAC__StreamMetadata_StreamInfo stream_info; /* we keep this around so we can figure out how to seek quickly */
  63         const FLAC__StreamMetadata_SeekTable *seek_table; /* we hold a pointer to the stream decoder's seek table for the same reason */
  64         /* Since we always want to see the STREAMINFO and SEEK_TABLE blocks at this level, we need some extra flags to keep track of whether they should be passed on up through the metadata_callback */
  65         FLAC__bool ignore_stream_info_block;
  66         FLAC__bool ignore_seek_table_block;
  67         FLAC__Frame last_frame; /* holds the info of the last frame we seeked to */
  68         FLAC__uint64 target_sample;
  69 } FLAC__SeekableStreamDecoderPrivate;
  70
  71 /***********************************************************************
  72  *
  73  * Public static class data
  74  *
  75  ***********************************************************************/
  76
  77 const char * const FLAC__SeekableStreamDecoderStateString[] = {
  78         "FLAC__SEEKABLE_STREAM_DECODER_OK",
  79         "FLAC__SEEKABLE_STREAM_DECODER_SEEKING",
  80         "FLAC__SEEKABLE_STREAM_DECODER_END_OF_STREAM",
  81         "FLAC__SEEKABLE_STREAM_DECODER_MEMORY_ALLOCATION_ERROR",
  82         "FLAC__SEEKABLE_STREAM_DECODER_STREAM_DECODER_ERROR",
  83         "FLAC__SEEKABLE_STREAM_DECODER_READ_ERROR",
  84         "FLAC__SEEKABLE_STREAM_DECODER_SEEK_ERROR",
  85     "FLAC__SEEKABLE_STREAM_DECODER_ALREADY_INITIALIZED",
  86     "FLAC__SEEKABLE_STREAM_DECODER_INVALID_CALLBACK",
  87     "FLAC__SEEKABLE_STREAM_DECODER_UNINITIALIZED"
  88 };
  89
  90 const char * const FLAC__SeekableStreamDecoderReadStatusString[] = {
  91         "FLAC__SEEKABLE_STREAM_DECODER_READ_STATUS_OK",
  92         "FLAC__SEEKABLE_STREAM_DECODER_READ_STATUS_ERROR"
  93 };
  94
  95 const char * const FLAC__SeekableStreamDecoderSeekStatusString[] = {
  96         "FLAC__SEEKABLE_STREAM_DECODER_SEEK_STATUS_OK",
  97         "FLAC__SEEKABLE_STREAM_DECODER_SEEK_STATUS_ERROR"
  98 };
  99
 100 const char * const FLAC__SeekableStreamDecoderTellStatusString[] = {
 101         "FLAC__SEEKABLE_STREAM_DECODER_TELL_STATUS_OK",
 102         "FLAC__SEEKABLE_STREAM_DECODER_TELL_STATUS_ERROR"
 103 };
 104
 105 const char * const FLAC__SeekableStreamDecoderLengthStatusString[] = {
 106         "FLAC__SEEKABLE_STREAM_DECODER_LENGTH_STATUS_OK",
 107         "FLAC__SEEKABLE_STREAM_DECODER_LENGTH_STATUS_ERROR"
 108 };
 109
 110 /***********************************************************************
 111  *
 112  * Class constructor/destructor
 113  *
 114  ***********************************************************************/
 115
 116 FLAC__SeekableStreamDecoder *FLAC__seekable_stream_decoder_new()
 117 {
 118         FLAC__SeekableStreamDecoder *decoder;
 119
 120         FLAC__ASSERT(sizeof(int) >= 4); /* we want to die right away if this is not true */
 121
 122         decoder = (FLAC__SeekableStreamDecoder*)malloc(sizeof(FLAC__SeekableStreamDecoder));
 123         if(decoder == 0) {
 124                 return 0;
 125         }
 126         decoder->protected_ = (FLAC__SeekableStreamDecoderProtected*)malloc(sizeof(FLAC__SeekableStreamDecoderProtected));
 127         if(decoder->protected_ == 0) {
 128                 free(decoder);
 129                 return 0;
 130         }
 131         decoder->private_ = (FLAC__SeekableStreamDecoderPrivate*)malloc(sizeof(FLAC__SeekableStreamDecoderPrivate));
 132         if(decoder->private_ == 0) {
 133                 free(decoder->protected_);
 134                 free(decoder);
 135                 return 0;
 136         }
 137
 138         decoder->private_->stream_decoder = FLAC__stream_decoder_new();
 139
 140         if(0 == decoder->private_->stream_decoder) {
 141                 free(decoder->private_);
 142                 free(decoder->protected_);
 143                 free(decoder);
 144                 return 0;
 145         }
 146
 147         seekable_stream_decoder_set_defaults_(decoder);
 148
 149         decoder->protected_->state = FLAC__SEEKABLE_STREAM_DECODER_UNINITIALIZED;
 150
 151         return decoder;
 152 }
 153
 154 void FLAC__seekable_stream_decoder_delete(FLAC__SeekableStreamDecoder *decoder)
 155 {
 156         FLAC__ASSERT(decoder != 0);
 157         FLAC__ASSERT(decoder->protected_ != 0);
 158         FLAC__ASSERT(decoder->private_ != 0);
 159         FLAC__ASSERT(decoder->private_->stream_decoder != 0);
 160
 161         (void)FLAC__seekable_stream_decoder_finish(decoder);
 162
 163         FLAC__stream_decoder_delete(decoder->private_->stream_decoder);
 164
 165         free(decoder->private_);
 166         free(decoder->protected_);
 167         free(decoder);
 168 }
 169
 170 /***********************************************************************
 171  *
 172  * Public class methods
 173  *
 174  ***********************************************************************/
 175
 176 FLAC__SeekableStreamDecoderState FLAC__seekable_stream_decoder_init(FLAC__SeekableStreamDecoder *decoder)
 177 {
 178         FLAC__ASSERT(decoder != 0);
 179
 180         if(decoder->protected_->state != FLAC__SEEKABLE_STREAM_DECODER_UNINITIALIZED)
 181                 return decoder->protected_->state = FLAC__SEEKABLE_STREAM_DECODER_ALREADY_INITIALIZED;
 182
 183         if(0 == decoder->private_->read_callback || 0 == decoder->private_->seek_callback || 0 == decoder->private_->tell_callback || 0 == decoder->private_->length_callback || 0 == decoder->private_->eof_callback)
 184                 return decoder->protected_->state = FLAC__SEEKABLE_STREAM_DECODER_INVALID_CALLBACK;
 185
 186         if(0 == decoder->private_->write_callback || 0 == decoder->private_->metadata_callback || 0 == decoder->private_->error_callback)
 187                 return decoder->protected_->state = FLAC__SEEKABLE_STREAM_DECODER_INVALID_CALLBACK;
 188
 189         decoder->private_->seek_table = 0;
 190
 191         /* We initialize the MD5Context even though we may never use it.  This is
 192          * because md5_checking may be turned on to start and then turned off if a
 193          * seek occurs.  So we always init the context here and finalize it in
 194          * FLAC__seekable_stream_decoder_finish() to make sure things are always
 195          * cleaned up properly.
 196          */
 197         MD5Init(&decoder->private_->md5context);
 198
 199         FLAC__stream_decoder_set_read_callback(decoder->private_->stream_decoder, read_callback_);
 200         FLAC__stream_decoder_set_write_callback(decoder->private_->stream_decoder, write_callback_);
 201         FLAC__stream_decoder_set_metadata_callback(decoder->private_->stream_decoder, metadata_callback_);
 202         FLAC__stream_decoder_set_error_callback(decoder->private_->stream_decoder, error_callback_);
 203         FLAC__stream_decoder_set_client_data(decoder->private_->stream_decoder, decoder);
 204
 205         /* We always want to see these blocks.  Whether or not we pass them up
 206          * through the metadata callback will be determined by flags set in our
 207          * implementation of ..._set_metadata_respond/ignore...()
 208          */
 209         FLAC__stream_decoder_set_metadata_respond(decoder->private_->stream_decoder, FLAC__METADATA_TYPE_STREAMINFO);
 210         FLAC__stream_decoder_set_metadata_respond(decoder->private_->stream_decoder, FLAC__METADATA_TYPE_SEEKTABLE);
 211
 212         if(FLAC__stream_decoder_init(decoder->private_->stream_decoder) != FLAC__STREAM_DECODER_SEARCH_FOR_METADATA)
 213                 return decoder->protected_->state = FLAC__SEEKABLE_STREAM_DECODER_STREAM_DECODER_ERROR;
 214
 215         return decoder->protected_->state = FLAC__SEEKABLE_STREAM_DECODER_OK;
 216 }
 217
 218 FLAC__bool FLAC__seekable_stream_decoder_finish(FLAC__SeekableStreamDecoder *decoder)
 219 {
 220         FLAC__bool md5_failed = false;
 221
 222         FLAC__ASSERT(decoder != 0);
 223         FLAC__ASSERT(decoder->private_ != 0);
 224         FLAC__ASSERT(decoder->protected_ != 0);
 225
 226         if(decoder->protected_->state == FLAC__SEEKABLE_STREAM_DECODER_UNINITIALIZED)
 227                 return true;
 228
 229         FLAC__ASSERT(decoder->private_->stream_decoder != 0);
 230
 231         /* see the comment in FLAC__seekable_stream_decoder_init() as to why we
 232          * always call MD5Final()
 233          */
 234         MD5Final(decoder->private_->computed_md5sum, &decoder->private_->md5context);
 235
 236         FLAC__stream_decoder_finish(decoder->private_->stream_decoder);
 237
 238         if(decoder->protected_->md5_checking) {
 239                 if(memcmp(decoder->private_->stored_md5sum, decoder->private_->computed_md5sum, 16))
 240                         md5_failed = true;
 241         }
 242
 243         seekable_stream_decoder_set_defaults_(decoder);
 244
 245         decoder->protected_->state = FLAC__SEEKABLE_STREAM_DECODER_UNINITIALIZED;
 246
 247         return !md5_failed;
 248 }
 249
 250 FLAC__bool FLAC__seekable_stream_decoder_set_md5_checking(FLAC__SeekableStreamDecoder *decoder, FLAC__bool value)
 251 {
 252         FLAC__ASSERT(decoder != 0);
 253         FLAC__ASSERT(decoder->protected_ != 0);
 254         if(decoder->protected_->state != FLAC__SEEKABLE_STREAM_DECODER_UNINITIALIZED)
 255                 return false;
 256         decoder->protected_->md5_checking = value;
 257         return true;
 258 }
 259
 260 FLAC__bool FLAC__seekable_stream_decoder_set_read_callback(FLAC__SeekableStreamDecoder *decoder, FLAC__SeekableStreamDecoderReadStatus (*value)(const FLAC__SeekableStreamDecoder *decoder, FLAC__byte buffer[], unsigned *bytes, void *client_data))
 261 {
 262         FLAC__ASSERT(decoder != 0);
 263         FLAC__ASSERT(decoder->private_ != 0);
 264         FLAC__ASSERT(decoder->protected_ != 0);
 265         if(decoder->protected_->state != FLAC__SEEKABLE_STREAM_DECODER_UNINITIALIZED)
 266                 return false;
 267         decoder->private_->read_callback = value;
 268         return true;
 269 }
 270
 271 FLAC__bool FLAC__seekable_stream_decoder_set_seek_callback(FLAC__SeekableStreamDecoder *decoder, FLAC__SeekableStreamDecoderSeekStatus (*value)(const FLAC__SeekableStreamDecoder *decoder, FLAC__uint64 absolute_byte_offset, void *client_data))
 272 {
 273         FLAC__ASSERT(decoder != 0);
 274         FLAC__ASSERT(decoder->private_ != 0);
 275         FLAC__ASSERT(decoder->protected_ != 0);
 276         if(decoder->protected_->state != FLAC__SEEKABLE_STREAM_DECODER_UNINITIALIZED)
 277                 return false;
 278         decoder->private_->seek_callback = value;
 279         return true;
 280 }
 281
 282 FLAC__bool FLAC__seekable_stream_decoder_set_tell_callback(FLAC__SeekableStreamDecoder *decoder, FLAC__SeekableStreamDecoderTellStatus (*value)(const FLAC__SeekableStreamDecoder *decoder, FLAC__uint64 *absolute_byte_offset, void *client_data))
 283 {
 284         FLAC__ASSERT(decoder != 0);
 285         FLAC__ASSERT(decoder->private_ != 0);
 286         FLAC__ASSERT(decoder->protected_ != 0);
 287         if(decoder->protected_->state != FLAC__SEEKABLE_STREAM_DECODER_UNINITIALIZED)
 288                 return false;
 289         decoder->private_->tell_callback = value;
 290         return true;
 291 }
 292
 293 FLAC__bool FLAC__seekable_stream_decoder_set_length_callback(FLAC__SeekableStreamDecoder *decoder, FLAC__SeekableStreamDecoderLengthStatus (*value)(const FLAC__SeekableStreamDecoder *decoder, FLAC__uint64 *stream_length, void *client_data))
 294 {
 295         FLAC__ASSERT(decoder != 0);
 296         FLAC__ASSERT(decoder->private_ != 0);
 297         FLAC__ASSERT(decoder->protected_ != 0);
 298         if(decoder->protected_->state != FLAC__SEEKABLE_STREAM_DECODER_UNINITIALIZED)
 299                 return false;
 300         decoder->private_->length_callback = value;
 301         return true;
 302 }
 303
 304 FLAC__bool FLAC__seekable_stream_decoder_set_eof_callback(FLAC__SeekableStreamDecoder *decoder, FLAC__bool (*value)(const FLAC__SeekableStreamDecoder *decoder, void *client_data))
 305 {
 306         FLAC__ASSERT(decoder != 0);
 307         FLAC__ASSERT(decoder->private_ != 0);
 308         FLAC__ASSERT(decoder->protected_ != 0);
 309         if(decoder->protected_->state != FLAC__SEEKABLE_STREAM_DECODER_UNINITIALIZED)
 310                 return false;
 311         decoder->private_->eof_callback = value;
 312         return true;
 313 }
 314
 315 FLAC__bool FLAC__seekable_stream_decoder_set_write_callback(FLAC__SeekableStreamDecoder *decoder, FLAC__StreamDecoderWriteStatus (*value)(const FLAC__SeekableStreamDecoder *decoder, const FLAC__Frame *frame, const FLAC__int32 * const buffer[], void *client_data))
 316 {
 317         FLAC__ASSERT(decoder != 0);
 318         FLAC__ASSERT(decoder->private_ != 0);
 319         FLAC__ASSERT(decoder->protected_ != 0);
 320         if(decoder->protected_->state != FLAC__SEEKABLE_STREAM_DECODER_UNINITIALIZED)
 321                 return false;
 322         decoder->private_->write_callback = value;
 323         return true;
 324 }
 325
 326 FLAC__bool FLAC__seekable_stream_decoder_set_metadata_callback(FLAC__SeekableStreamDecoder *decoder, void (*value)(const FLAC__SeekableStreamDecoder *decoder, const FLAC__StreamMetadata *metadata, void *client_data))
 327 {
 328         FLAC__ASSERT(decoder != 0);
 329         FLAC__ASSERT(decoder->private_ != 0);
 330         FLAC__ASSERT(decoder->protected_ != 0);
 331         if(decoder->protected_->state != FLAC__SEEKABLE_STREAM_DECODER_UNINITIALIZED)
 332                 return false;
 333         decoder->private_->metadata_callback = value;
 334         return true;
 335 }
 336
 337 FLAC__bool FLAC__seekable_stream_decoder_set_error_callback(FLAC__SeekableStreamDecoder *decoder, void (*value)(const FLAC__SeekableStreamDecoder *decoder, FLAC__StreamDecoderErrorStatus status, void *client_data))
 338 {
 339         FLAC__ASSERT(decoder != 0);
 340         FLAC__ASSERT(decoder->private_ != 0);
 341         FLAC__ASSERT(decoder->protected_ != 0);
 342         if(decoder->protected_->state != FLAC__SEEKABLE_STREAM_DECODER_UNINITIALIZED)
 343                 return false;
 344         decoder->private_->error_callback = value;
 345         return true;
 346 }
 347
 348 FLAC__bool FLAC__seekable_stream_decoder_set_client_data(FLAC__SeekableStreamDecoder *decoder, void *value)
 349 {
 350         FLAC__ASSERT(decoder != 0);
 351         FLAC__ASSERT(decoder->private_ != 0);
 352         FLAC__ASSERT(decoder->protected_ != 0);
 353         if(decoder->protected_->state != FLAC__SEEKABLE_STREAM_DECODER_UNINITIALIZED)
 354                 return false;
 355         decoder->private_->client_data = value;
 356         return true;
 357 }
 358
 359 FLAC__bool FLAC__seekable_stream_decoder_set_metadata_respond(FLAC__SeekableStreamDecoder *decoder, FLAC__MetadataType type)
 360 {
 361         FLAC__ASSERT(decoder != 0);
 362         FLAC__ASSERT(decoder->private_ != 0);
 363         FLAC__ASSERT(decoder->protected_ != 0);
 364         FLAC__ASSERT(decoder->private_->stream_decoder != 0);
 365         if(decoder->protected_->state != FLAC__SEEKABLE_STREAM_DECODER_UNINITIALIZED)
 366                 return false;
 367         if(type == FLAC__METADATA_TYPE_STREAMINFO)
 368                 decoder->private_->ignore_stream_info_block = false;
 369         else if(type == FLAC__METADATA_TYPE_SEEKTABLE)
 370                 decoder->private_->ignore_seek_table_block = false;
 371         return FLAC__stream_decoder_set_metadata_respond(decoder->private_->stream_decoder, type);
 372 }
 373
 374 FLAC__bool FLAC__seekable_stream_decoder_set_metadata_respond_application(FLAC__SeekableStreamDecoder *decoder, const FLAC__byte id[4])
 375 {
 376         FLAC__ASSERT(decoder != 0);
 377         FLAC__ASSERT(decoder->private_ != 0);
 378         FLAC__ASSERT(decoder->protected_ != 0);
 379         FLAC__ASSERT(decoder->private_->stream_decoder != 0);
 380         if(decoder->protected_->state != FLAC__SEEKABLE_STREAM_DECODER_UNINITIALIZED)
 381                 return false;
 382         return FLAC__stream_decoder_set_metadata_respond_application(decoder->private_->stream_decoder, id);
 383 }
 384
 385 FLAC__bool FLAC__seekable_stream_decoder_set_metadata_respond_all(FLAC__SeekableStreamDecoder *decoder)
 386 {
 387         FLAC__ASSERT(decoder != 0);
 388         FLAC__ASSERT(decoder->private_ != 0);
 389         FLAC__ASSERT(decoder->protected_ != 0);
 390         FLAC__ASSERT(decoder->private_->stream_decoder != 0);
 391         if(decoder->protected_->state != FLAC__SEEKABLE_STREAM_DECODER_UNINITIALIZED)
 392                 return false;
 393         decoder->private_->ignore_stream_info_block = false;
 394         decoder->private_->ignore_seek_table_block = false;
 395         return FLAC__stream_decoder_set_metadata_respond_all(decoder->private_->stream_decoder);
 396 }
 397
 398 FLAC__bool FLAC__seekable_stream_decoder_set_metadata_ignore(FLAC__SeekableStreamDecoder *decoder, FLAC__MetadataType type)
 399 {
 400         FLAC__ASSERT(decoder != 0);
 401         FLAC__ASSERT(decoder->private_ != 0);
 402         FLAC__ASSERT(decoder->protected_ != 0);
 403         FLAC__ASSERT(decoder->private_->stream_decoder != 0);
 404         if(decoder->protected_->state != FLAC__SEEKABLE_STREAM_DECODER_UNINITIALIZED)
 405                 return false;
 406         if(type == FLAC__METADATA_TYPE_STREAMINFO)
 407                 decoder->private_->ignore_stream_info_block = true;
 408         else if(type == FLAC__METADATA_TYPE_SEEKTABLE)
 409                 decoder->private_->ignore_seek_table_block = true;
 410         return FLAC__stream_decoder_set_metadata_ignore(decoder->private_->stream_decoder, type);
 411 }
 412
 413 FLAC__bool FLAC__seekable_stream_decoder_set_metadata_ignore_application(FLAC__SeekableStreamDecoder *decoder, const FLAC__byte id[4])
 414 {
 415         FLAC__ASSERT(decoder != 0);
 416         FLAC__ASSERT(decoder->private_ != 0);
 417         FLAC__ASSERT(decoder->protected_ != 0);
 418         FLAC__ASSERT(decoder->private_->stream_decoder != 0);
 419         if(decoder->protected_->state != FLAC__SEEKABLE_STREAM_DECODER_UNINITIALIZED)
 420                 return false;
 421         return FLAC__stream_decoder_set_metadata_ignore_application(decoder->private_->stream_decoder, id);
 422 }
 423
 424 FLAC__bool FLAC__seekable_stream_decoder_set_metadata_ignore_all(FLAC__SeekableStreamDecoder *decoder)
 425 {
 426         FLAC__ASSERT(decoder != 0);
 427         FLAC__ASSERT(decoder->private_ != 0);
 428         FLAC__ASSERT(decoder->protected_ != 0);
 429         FLAC__ASSERT(decoder->private_->stream_decoder != 0);
 430         if(decoder->protected_->state != FLAC__SEEKABLE_STREAM_DECODER_UNINITIALIZED)
 431                 return false;
 432         decoder->private_->ignore_stream_info_block = true;
 433         decoder->private_->ignore_seek_table_block = true;
 434         return FLAC__stream_decoder_set_metadata_ignore_all(decoder->private_->stream_decoder);
 435 }
 436
 437 FLAC__SeekableStreamDecoderState FLAC__seekable_stream_decoder_get_state(const FLAC__SeekableStreamDecoder *decoder)
 438 {
 439         FLAC__ASSERT(decoder != 0);
 440         FLAC__ASSERT(decoder->protected_ != 0);
 441         return decoder->protected_->state;
 442 }
 443
 444 FLAC__bool FLAC__seekable_stream_decoder_get_md5_checking(const FLAC__SeekableStreamDecoder *decoder)
 445 {
 446         FLAC__ASSERT(decoder != 0);
 447         FLAC__ASSERT(decoder->protected_ != 0);
 448         return decoder->protected_->md5_checking;
 449 }
 450
 451 unsigned FLAC__seekable_stream_decoder_get_channels(const FLAC__SeekableStreamDecoder *decoder)
 452 {
 453     FLAC__ASSERT(decoder != 0);
 454     FLAC__ASSERT(decoder->private_ != 0);
 455     return FLAC__stream_decoder_get_channels(decoder->private_->stream_decoder);
 456 }
 457
 458 FLAC__ChannelAssignment FLAC__seekable_stream_decoder_get_channel_assignment(const FLAC__SeekableStreamDecoder *decoder)
 459 {
 460     FLAC__ASSERT(decoder != 0);
 461     FLAC__ASSERT(decoder->private_ != 0);
 462     return FLAC__stream_decoder_get_channel_assignment(decoder->private_->stream_decoder);
 463 }
 464
 465 unsigned FLAC__seekable_stream_decoder_get_bits_per_sample(const FLAC__SeekableStreamDecoder *decoder)
 466 {
 467     FLAC__ASSERT(decoder != 0);
 468     FLAC__ASSERT(decoder->private_ != 0);
 469     return FLAC__stream_decoder_get_bits_per_sample(decoder->private_->stream_decoder);
 470 }
 471
 472 unsigned FLAC__seekable_stream_decoder_get_sample_rate(const FLAC__SeekableStreamDecoder *decoder)
 473 {
 474     FLAC__ASSERT(decoder != 0);
 475     FLAC__ASSERT(decoder->private_ != 0);
 476     return FLAC__stream_decoder_get_sample_rate(decoder->private_->stream_decoder);
 477 }
 478
 479 unsigned FLAC__seekable_stream_decoder_get_blocksize(const FLAC__SeekableStreamDecoder *decoder)
 480 {
 481     FLAC__ASSERT(decoder != 0);
 482     FLAC__ASSERT(decoder->private_ != 0);
 483     return FLAC__stream_decoder_get_blocksize(decoder->private_->stream_decoder);
 484 }
 485
 486 FLAC__bool FLAC__seekable_stream_decoder_flush(FLAC__SeekableStreamDecoder *decoder)
 487 {
 488         FLAC__ASSERT(decoder != 0);
 489         FLAC__ASSERT(decoder->private_ != 0);
 490         FLAC__ASSERT(decoder->protected_ != 0);
 491
 492         decoder->protected_->md5_checking = false;
 493
 494         if(!FLAC__stream_decoder_flush(decoder->private_->stream_decoder)) {
 495                 decoder->protected_->state = FLAC__SEEKABLE_STREAM_DECODER_STREAM_DECODER_ERROR;
 496                 return false;
 497         }
 498
 499         return true;
 500 }
 501
 502 FLAC__bool FLAC__seekable_stream_decoder_reset(FLAC__SeekableStreamDecoder *decoder)
 503 {
 504         FLAC__ASSERT(decoder != 0);
 505         FLAC__ASSERT(decoder->private_ != 0);
 506         FLAC__ASSERT(decoder->protected_ != 0);
 507
 508         if(!FLAC__seekable_stream_decoder_flush(decoder)) {
 509                 decoder->protected_->state = FLAC__SEEKABLE_STREAM_DECODER_STREAM_DECODER_ERROR;
 510                 return false;
 511         }
 512
 513         if(!FLAC__stream_decoder_reset(decoder->private_->stream_decoder)) {
 514                 decoder->protected_->state = FLAC__SEEKABLE_STREAM_DECODER_STREAM_DECODER_ERROR;
 515                 return false;
 516         }
 517
 518         decoder->private_->seek_table = 0;
 519
 520         decoder->protected_->state = FLAC__SEEKABLE_STREAM_DECODER_OK;
 521
 522         return true;
 523 }
 524
 525 FLAC__bool FLAC__seekable_stream_decoder_process_whole_stream(FLAC__SeekableStreamDecoder *decoder)
 526 {
 527         FLAC__bool ret;
 528         FLAC__ASSERT(decoder != 0);
 529
 530         if(decoder->private_->stream_decoder->protected_->state == FLAC__STREAM_DECODER_END_OF_STREAM)
 531                 decoder->protected_->state = FLAC__SEEKABLE_STREAM_DECODER_END_OF_STREAM;
 532
 533         if(decoder->protected_->state == FLAC__SEEKABLE_STREAM_DECODER_END_OF_STREAM)
 534                 return true;
 535
 536         FLAC__ASSERT(decoder->protected_->state == FLAC__SEEKABLE_STREAM_DECODER_OK);
 537
 538         ret = FLAC__stream_decoder_process_whole_stream(decoder->private_->stream_decoder);
 539         if(!ret)
 540                 decoder->protected_->state = FLAC__SEEKABLE_STREAM_DECODER_STREAM_DECODER_ERROR;
 541
 542         return ret;
 543 }
 544
 545 FLAC__bool FLAC__seekable_stream_decoder_process_metadata(FLAC__SeekableStreamDecoder *decoder)
 546 {
 547         FLAC__bool ret;
 548         FLAC__ASSERT(decoder != 0);
 549
 550         if(decoder->private_->stream_decoder->protected_->state == FLAC__STREAM_DECODER_END_OF_STREAM)
 551                 decoder->protected_->state = FLAC__SEEKABLE_STREAM_DECODER_END_OF_STREAM;
 552
 553         if(decoder->protected_->state == FLAC__SEEKABLE_STREAM_DECODER_END_OF_STREAM)
 554                 return true;
 555
 556         FLAC__ASSERT(decoder->protected_->state == FLAC__SEEKABLE_STREAM_DECODER_OK);
 557
 558         ret = FLAC__stream_decoder_process_metadata(decoder->private_->stream_decoder);
 559         if(!ret)
 560                 decoder->protected_->state = FLAC__SEEKABLE_STREAM_DECODER_STREAM_DECODER_ERROR;
 561
 562         return ret;
 563 }
 564
 565 FLAC__bool FLAC__seekable_stream_decoder_process_one_frame(FLAC__SeekableStreamDecoder *decoder)
 566 {
 567         FLAC__bool ret;
 568         FLAC__ASSERT(decoder != 0);
 569
 570         if(decoder->private_->stream_decoder->protected_->state == FLAC__STREAM_DECODER_END_OF_STREAM)
 571                 decoder->protected_->state = FLAC__SEEKABLE_STREAM_DECODER_END_OF_STREAM;
 572
 573         if(decoder->protected_->state == FLAC__SEEKABLE_STREAM_DECODER_END_OF_STREAM)
 574                 return true;
 575
 576         FLAC__ASSERT(decoder->protected_->state == FLAC__SEEKABLE_STREAM_DECODER_OK);
 577
 578         ret = FLAC__stream_decoder_process_one_frame(decoder->private_->stream_decoder);
 579         if(!ret)
 580                 decoder->protected_->state = FLAC__SEEKABLE_STREAM_DECODER_STREAM_DECODER_ERROR;
 581
 582         return ret;
 583 }
 584
 585 FLAC__bool FLAC__seekable_stream_decoder_process_remaining_frames(FLAC__SeekableStreamDecoder *decoder)
 586 {
 587         FLAC__bool ret;
 588         FLAC__ASSERT(decoder != 0);
 589
 590         if(decoder->private_->stream_decoder->protected_->state == FLAC__STREAM_DECODER_END_OF_STREAM)
 591                 decoder->protected_->state = FLAC__SEEKABLE_STREAM_DECODER_END_OF_STREAM;
 592
 593         if(decoder->protected_->state == FLAC__SEEKABLE_STREAM_DECODER_END_OF_STREAM)
 594                 return true;
 595
 596         FLAC__ASSERT(decoder->protected_->state == FLAC__SEEKABLE_STREAM_DECODER_OK);
 597
 598         ret = FLAC__stream_decoder_process_remaining_frames(decoder->private_->stream_decoder);
 599         if(!ret)
 600                 decoder->protected_->state = FLAC__SEEKABLE_STREAM_DECODER_STREAM_DECODER_ERROR;
 601
 602         return ret;
 603 }
 604
 605 FLAC__bool FLAC__seekable_stream_decoder_seek_absolute(FLAC__SeekableStreamDecoder *decoder, FLAC__uint64 sample)
 606 {
 607         FLAC__uint64 length;
 608
 609         FLAC__ASSERT(decoder != 0);
 610         FLAC__ASSERT(decoder->protected_->state == FLAC__SEEKABLE_STREAM_DECODER_OK || decoder->protected_->state == FLAC__SEEKABLE_STREAM_DECODER_END_OF_STREAM);
 611
 612         decoder->protected_->state = FLAC__SEEKABLE_STREAM_DECODER_SEEKING;
 613
 614         /* turn off md5 checking if a seek is attempted */
 615         decoder->protected_->md5_checking = false;
 616
 617         if(!FLAC__stream_decoder_reset(decoder->private_->stream_decoder)) {
 618                 decoder->protected_->state = FLAC__SEEKABLE_STREAM_DECODER_STREAM_DECODER_ERROR;
 619                 return false;
 620         }
 621         /* get the file length */
 622         if(decoder->private_->length_callback(decoder, &length, decoder->private_->client_data) != FLAC__SEEKABLE_STREAM_DECODER_LENGTH_STATUS_OK) {
 623                 decoder->protected_->state = FLAC__SEEKABLE_STREAM_DECODER_SEEK_ERROR;
 624                 return false;
 625         }
 626         /* rewind */
 627         if(decoder->private_->seek_callback(decoder, 0, decoder->private_->client_data) != FLAC__SEEKABLE_STREAM_DECODER_SEEK_STATUS_OK) {
 628                 decoder->protected_->state = FLAC__SEEKABLE_STREAM_DECODER_SEEK_ERROR;
 629                 return false;
 630         }
 631         if(!FLAC__stream_decoder_process_metadata(decoder->private_->stream_decoder)) {
 632                 decoder->protected_->state = FLAC__SEEKABLE_STREAM_DECODER_STREAM_DECODER_ERROR;
 633                 return false;
 634         }
 635         if(decoder->private_->stream_info.total_samples > 0 && sample > decoder->private_->stream_info.total_samples) {
 636                 decoder->protected_->state = FLAC__SEEKABLE_STREAM_DECODER_SEEK_ERROR;
 637                 return false;
 638         }
 639
 640         return seek_to_absolute_sample_(decoder, length, sample);
 641 }
 642
 643 /***********************************************************************
 644  *
 645  * Private class methods
 646  *
 647  ***********************************************************************/
 648
 649 void seekable_stream_decoder_set_defaults_(FLAC__SeekableStreamDecoder *decoder)
 650 {
 651         decoder->private_->read_callback = 0;
 652         decoder->private_->seek_callback = 0;
 653         decoder->private_->tell_callback = 0;
 654         decoder->private_->length_callback = 0;
 655         decoder->private_->eof_callback = 0;
 656         decoder->private_->write_callback = 0;
 657         decoder->private_->metadata_callback = 0;
 658         decoder->private_->error_callback = 0;
 659         decoder->private_->client_data = 0;
 660         /* WATCHOUT: these should match the default behavior of FLAC__StreamDecoder */
 661         decoder->private_->ignore_stream_info_block = false;
 662         decoder->private_->ignore_seek_table_block = true;
 663
 664         decoder->protected_->md5_checking = false;
 665 }
 666
 667 FLAC__StreamDecoderReadStatus read_callback_(const FLAC__StreamDecoder *decoder, FLAC__byte buffer[], unsigned *bytes, void *client_data)
 668 {
 669         FLAC__SeekableStreamDecoder *seekable_stream_decoder = (FLAC__SeekableStreamDecoder *)client_data;
 670         (void)decoder;
 671         if(seekable_stream_decoder->private_->eof_callback(seekable_stream_decoder, seekable_stream_decoder->private_->client_data)) {
 672                 seekable_stream_decoder->protected_->state = FLAC__SEEKABLE_STREAM_DECODER_END_OF_STREAM;
 673                 return FLAC__STREAM_DECODER_READ_STATUS_END_OF_STREAM;
 674         }
 675         else if(*bytes > 0) {
 676                 unsigned bytes_read = *bytes;
 677                 if(seekable_stream_decoder->private_->read_callback(seekable_stream_decoder, buffer, &bytes_read, seekable_stream_decoder->private_->client_data) != FLAC__SEEKABLE_STREAM_DECODER_READ_STATUS_OK) {
 678                         seekable_stream_decoder->protected_->state = FLAC__SEEKABLE_STREAM_DECODER_READ_ERROR;
 679                         return FLAC__STREAM_DECODER_READ_STATUS_ABORT;
 680                 }
 681                 if(bytes_read == 0) {
 682                         if(seekable_stream_decoder->private_->eof_callback(seekable_stream_decoder, seekable_stream_decoder->private_->client_data)) {
 683                                 seekable_stream_decoder->protected_->state = FLAC__SEEKABLE_STREAM_DECODER_END_OF_STREAM;
 684                                 return FLAC__STREAM_DECODER_READ_STATUS_END_OF_STREAM;
 685                         }
 686                         else
 687                                 return FLAC__STREAM_DECODER_READ_STATUS_CONTINUE;
 688                 }
 689                 else {
 690                         *bytes = bytes_read;
 691                         return FLAC__STREAM_DECODER_READ_STATUS_CONTINUE;
 692                 }
 693         }
 694         else
 695                 return FLAC__STREAM_DECODER_READ_STATUS_ABORT; /* abort to avoid a deadlock */
 696 }
 697
 698 FLAC__StreamDecoderWriteStatus write_callback_(const FLAC__StreamDecoder *decoder, const FLAC__Frame *frame, const FLAC__int32 * const buffer[], void *client_data)
 699 {
 700         FLAC__SeekableStreamDecoder *seekable_stream_decoder = (FLAC__SeekableStreamDecoder *)client_data;
 701         (void)decoder;
 702
 703         if(seekable_stream_decoder->protected_->state == FLAC__SEEKABLE_STREAM_DECODER_SEEKING) {
 704                 FLAC__uint64 this_frame_sample = frame->header.number.sample_number;
 705                 FLAC__uint64 next_frame_sample = this_frame_sample + (FLAC__uint64)frame->header.blocksize;
 706                 FLAC__uint64 target_sample = seekable_stream_decoder->private_->target_sample;
 707
 708                 FLAC__ASSERT(frame->header.number_type == FLAC__FRAME_NUMBER_TYPE_SAMPLE_NUMBER);
 709
 710                 seekable_stream_decoder->private_->last_frame = *frame; /* save the frame */
 711                 if(this_frame_sample <= target_sample && target_sample < next_frame_sample) { /* we hit our target frame */
 712                         unsigned delta = (unsigned)(target_sample - this_frame_sample);
 713                         /* kick out of seek mode */
 714                         seekable_stream_decoder->protected_->state = FLAC__SEEKABLE_STREAM_DECODER_OK;
 715                         /* shift out the samples before target_sample */
 716                         if(delta > 0) {
 717                                 unsigned channel;
 718                                 const FLAC__int32 *newbuffer[FLAC__MAX_CHANNELS];
 719                                 for(channel = 0; channel < frame->header.channels; channel++)
 720                                         newbuffer[channel] = buffer[channel] + delta;
 721                                 seekable_stream_decoder->private_->last_frame.header.blocksize -= delta;
 722                                 seekable_stream_decoder->private_->last_frame.header.number.sample_number += (FLAC__uint64)delta;
 723                                 /* write the relevant samples */
 724                                 return seekable_stream_decoder->private_->write_callback(seekable_stream_decoder, &seekable_stream_decoder->private_->last_frame, newbuffer, seekable_stream_decoder->private_->client_data);
 725                         }
 726                         else {
 727                                 /* write the relevant samples */
 728                                 return seekable_stream_decoder->private_->write_callback(seekable_stream_decoder, frame, buffer, seekable_stream_decoder->private_->client_data);
 729                         }
 730                 }
 731                 else {
 732                         return FLAC__STREAM_DECODER_WRITE_STATUS_CONTINUE;
 733                 }
 734         }
 735         else {
 736                 if(seekable_stream_decoder->protected_->md5_checking) {
 737                         if(!FLAC__MD5Accumulate(&seekable_stream_decoder->private_->md5context, buffer, frame->header.channels, frame->header.blocksize, (frame->header.bits_per_sample+7) / 8))
 738                                 return FLAC__STREAM_DECODER_WRITE_STATUS_ABORT;
 739                 }
 740                 return seekable_stream_decoder->private_->write_callback(seekable_stream_decoder, frame, buffer, seekable_stream_decoder->private_->client_data);
 741         }
 742 }
 743
 744 void metadata_callback_(const FLAC__StreamDecoder *decoder, const FLAC__StreamMetadata *metadata, void *client_data)
 745 {
 746         FLAC__SeekableStreamDecoder *seekable_stream_decoder = (FLAC__SeekableStreamDecoder *)client_data;
 747         (void)decoder;
 748
 749         if(metadata->type == FLAC__METADATA_TYPE_STREAMINFO) {
 750                 seekable_stream_decoder->private_->stream_info = metadata->data.stream_info;
 751                 /* save the MD5 signature for comparison later */
 752                 memcpy(seekable_stream_decoder->private_->stored_md5sum, metadata->data.stream_info.md5sum, 16);
 753                 if(0 == memcmp(seekable_stream_decoder->private_->stored_md5sum, "\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0", 16))
 754                         seekable_stream_decoder->protected_->md5_checking = false;
 755         }
 756         else if(metadata->type == FLAC__METADATA_TYPE_SEEKTABLE) {
 757                 seekable_stream_decoder->private_->seek_table = &metadata->data.seek_table;
 758         }
 759
 760         if(seekable_stream_decoder->protected_->state != FLAC__SEEKABLE_STREAM_DECODER_SEEKING) {
 761                 FLAC__bool ignore_block = false;
 762                 if(metadata->type == FLAC__METADATA_TYPE_STREAMINFO && seekable_stream_decoder->private_->ignore_stream_info_block)
 763                         ignore_block = true;
 764                 else if(metadata->type == FLAC__METADATA_TYPE_SEEKTABLE && seekable_stream_decoder->private_->ignore_seek_table_block)
 765                         ignore_block = true;
 766                 if(!ignore_block)
 767                         seekable_stream_decoder->private_->metadata_callback(seekable_stream_decoder, metadata, seekable_stream_decoder->private_->client_data);
 768         }
 769 }
 770
 771 void error_callback_(const FLAC__StreamDecoder *decoder, FLAC__StreamDecoderErrorStatus status, void *client_data)
 772 {
 773         FLAC__SeekableStreamDecoder *seekable_stream_decoder = (FLAC__SeekableStreamDecoder *)client_data;
 774         (void)decoder;
 775
 776         if(seekable_stream_decoder->protected_->state != FLAC__SEEKABLE_STREAM_DECODER_SEEKING)
 777                 seekable_stream_decoder->private_->error_callback(seekable_stream_decoder, status, seekable_stream_decoder->private_->client_data);
 778 }
 779
 780 FLAC__bool seek_to_absolute_sample_(FLAC__SeekableStreamDecoder *decoder, FLAC__uint64 stream_length, FLAC__uint64 target_sample)
 781 {
 782         FLAC__uint64 first_frame_offset, lower_bound, upper_bound;
 783         FLAC__int64 pos = -1, last_pos = -1;
 784         int i, lower_seek_point = -1, upper_seek_point = -1;
 785         unsigned approx_bytes_per_frame;
 786         FLAC__uint64 last_frame_sample = 0xffffffffffffffff;
 787         FLAC__bool needs_seek;
 788         const FLAC__uint64 total_samples = decoder->private_->stream_info.total_samples;
 789         const unsigned min_blocksize = decoder->private_->stream_info.min_blocksize;
 790         const unsigned max_blocksize = decoder->private_->stream_info.max_blocksize;
 791         const unsigned max_framesize = decoder->private_->stream_info.max_framesize;
 792         const unsigned channels = FLAC__seekable_stream_decoder_get_channels(decoder);
 793         const unsigned bps = FLAC__seekable_stream_decoder_get_bits_per_sample(decoder);
 794
 795         /* we are just guessing here, but we want to guess high, not low */
 796         if(max_framesize > 0) {
 797                 approx_bytes_per_frame = max_framesize;
 798         }
 799         /*
 800          * Check if it's a known fixed-blocksize stream.  Note that though
 801          * the spec doesn't allow zeroes in the STREAMINFO block, we may
 802          * never get a STREAMINFO block when decoding so the value of
 803          * min_blocksize might be zero.
 804          */
 805         else if(min_blocksize == max_blocksize && min_blocksize > 0) {
 806                 /* note there are no () around 'bps/8' to keep precision up since it's an integer calulation */
 807                 approx_bytes_per_frame = min_blocksize * channels * bps/8 + 64;
 808         }
 809         else
 810                 approx_bytes_per_frame = 4608 * channels * bps/8 + 64;
 811
 812         /*
 813          * The stream position is currently at the first frame plus any read
 814          * ahead data, so first we get the stream position, then subtract
 815          * uncomsumed bytes to get the position of the first frame in the
 816          * stream.
 817          */
 818         if(decoder->private_->tell_callback(decoder, &first_frame_offset, decoder->private_->client_data) != FLAC__SEEKABLE_STREAM_DECODER_TELL_STATUS_OK) {
 819                 decoder->protected_->state = FLAC__SEEKABLE_STREAM_DECODER_SEEK_ERROR;
 820                 return false;
 821         }
 822         FLAC__ASSERT(first_frame_offset >= FLAC__stream_decoder_get_input_bytes_unconsumed(decoder->private_->stream_decoder));
 823         first_frame_offset -= FLAC__stream_decoder_get_input_bytes_unconsumed(decoder->private_->stream_decoder);
 824
 825         /*
 826          * First, we set an upper and lower bound on where in the
 827          * stream we will search.  For now we assume the worst case
 828          * scenario, which is our best guess at the beginning of
 829          * the first and last frames.
 830          */
 831         lower_bound = first_frame_offset;
 832
 833         /* calc the upper_bound, beyond which we never want to seek */
 834         if(max_framesize > 0)
 835                 upper_bound = stream_length - (max_framesize + 128 + 2); /* 128 for a possible ID3V1 tag, 2 for indexing differences */
 836         else
 837                 upper_bound = stream_length - ((channels * bps * FLAC__MAX_BLOCK_SIZE) / 8 + 128 + 2);
 838
 839         /*
 840          * Now we refine the bounds if we have a seektable with
 841          * suitable points.  Note that according to the spec they
 842          * must be ordered by ascending sample number.
 843          */
 844         if(0 != decoder->private_->seek_table) {
 845                 /* find the closest seek point <= target_sample, if it exists */
 846                 for(i = (int)decoder->private_->seek_table->num_points - 1; i >= 0; i--) {
 847                         if(decoder->private_->seek_table->points[i].sample_number != FLAC__STREAM_METADATA_SEEKPOINT_PLACEHOLDER && decoder->private_->seek_table->points[i].sample_number <= target_sample)
 848                                 break;
 849                 }
 850                 if(i >= 0) { /* i.e. we found a suitable seek point... */
 851                         lower_bound = first_frame_offset + decoder->private_->seek_table->points[i].stream_offset;
 852                         lower_seek_point = i;
 853                 }
 854
 855                 /* find the closest seek point > target_sample, if it exists */
 856                 for(i = 0; i < (int)decoder->private_->seek_table->num_points; i++) {
 857                         if(decoder->private_->seek_table->points[i].sample_number != FLAC__STREAM_METADATA_SEEKPOINT_PLACEHOLDER && decoder->private_->seek_table->points[i].sample_number > target_sample)
 858                                 break;
 859                 }
 860                 if(i < (int)decoder->private_->seek_table->num_points) { /* i.e. we found a suitable seek point... */
 861                         upper_bound = first_frame_offset + decoder->private_->seek_table->points[i].stream_offset;
 862                         upper_seek_point = i;
 863                 }
 864         }
 865
 866         /*
 867          * Now guess at where within those bounds our target
 868          * sample will be.
 869          */
 870         if(lower_seek_point >= 0) {
 871                 /* first see if our sample is within a few frames of the lower seekpoint */
 872                 if(decoder->private_->seek_table->points[lower_seek_point].sample_number <= target_sample && target_sample < decoder->private_->seek_table->points[lower_seek_point].sample_number + (decoder->private_->seek_table->points[lower_seek_point].frame_samples * 4)) {
 873                         pos = (FLAC__int64)lower_bound;
 874                 }
 875                 else if(upper_seek_point >= 0) {
 876                         const FLAC__uint64 target_offset = target_sample - decoder->private_->seek_table->points[lower_seek_point].sample_number;
 877                         const FLAC__uint64 range_samples = decoder->private_->seek_table->points[upper_seek_point].sample_number - decoder->private_->seek_table->points[lower_seek_point].sample_number;
 878                         const FLAC__uint64 range_bytes = upper_bound - lower_bound;
 879 #if defined _MSC_VER || defined __MINGW32__
 880                         /* with VC++ you have to spoon feed it the casting */
 881                         pos = (FLAC__int64)lower_bound + (FLAC__int64)((double)(FLAC__int64)target_offset / (double)(FLAC__int64)range_samples * (double)(FLAC__int64)(range_bytes-1)) - approx_bytes_per_frame;
 882 #else
 883                         pos = (FLAC__int64)lower_bound + (FLAC__int64)((double)target_offset / (double)range_samples * (double)(range_bytes-1)) - approx_bytes_per_frame;
 884 #endif
 885                 }
 886         }
 887
 888         /*
 889          * If there's no seek table, we need to use the metadata (if we
 890          * have it) and the filelength to estimate the position of the
 891          * frame with the correct sample.
 892          */
 893         if(pos < 0 && total_samples > 0) {
 894 #if defined _MSC_VER || defined __MINGW32__
 895                 /* with VC++ you have to spoon feed it the casting */
 896                 pos = (FLAC__int64)first_frame_offset + (FLAC__int64)((double)(FLAC__int64)target_sample / (double)(FLAC__int64)total_samples * (double)(FLAC__int64)(stream_length-first_frame_offset-1)) - approx_bytes_per_frame;
 897 #else
 898                 pos = (FLAC__int64)first_frame_offset + (FLAC__int64)((double)target_sample / (double)total_samples * (double)(stream_length-first_frame_offset-1)) - approx_bytes_per_frame;
 899 #endif
 900         }
 901
 902         /*
 903          * If there's no seek table and total_samples is unknown, we
 904          * don't even bother trying to figure out a target, we just use
 905          * our current position.
 906          */
 907         if(pos < 0) {
 908                 FLAC__uint64 upos;
 909                 if(decoder->private_->tell_callback(decoder, &upos, decoder->private_->client_data) != FLAC__SEEKABLE_STREAM_DECODER_TELL_STATUS_OK) {
 910                         decoder->protected_->state = FLAC__SEEKABLE_STREAM_DECODER_SEEK_ERROR;
 911                         return false;
 912                 }
 913                 pos = (FLAC__int32)upos;
 914                 needs_seek = false;
 915         }
 916         else
 917                 needs_seek = true;
 918
 919         /* clip the position to the bounds, lower bound takes precedence */
 920         if(pos >= (FLAC__int64)upper_bound) {
 921                 pos = (FLAC__int64)upper_bound-1;
 922                 needs_seek = true;
 923         }
 924         if(pos < (FLAC__int64)lower_bound) {
 925                 pos = (FLAC__int64)lower_bound;
 926                 needs_seek = true;
 927         }
 928
 929         decoder->private_->target_sample = target_sample;
 930         while(1) {
 931                 if(needs_seek) {
 932                         if(decoder->private_->seek_callback(decoder, (FLAC__uint64)pos, decoder->private_->client_data) != FLAC__SEEKABLE_STREAM_DECODER_SEEK_STATUS_OK) {
 933                                 decoder->protected_->state = FLAC__SEEKABLE_STREAM_DECODER_SEEK_ERROR;
 934                                 return false;
 935                         }
 936                         if(!FLAC__stream_decoder_flush(decoder->private_->stream_decoder)) {
 937                                 decoder->protected_->state = FLAC__SEEKABLE_STREAM_DECODER_STREAM_DECODER_ERROR;
 938                                 return false;
 939                         }
 940                 }
 941                 if(!FLAC__stream_decoder_process_one_frame(decoder->private_->stream_decoder)) {
 942                         decoder->protected_->state = FLAC__SEEKABLE_STREAM_DECODER_SEEK_ERROR;
 943                         return false;
 944                 }
 945                 /* our write callback will change the state when it gets to the target frame */
 946                 if(decoder->protected_->state != FLAC__SEEKABLE_STREAM_DECODER_SEEKING) {
 947                         break;
 948                 }
 949                 else { /* we need to narrow the search */
 950                         FLAC__uint64 this_frame_sample = decoder->private_->last_frame.header.number.sample_number;
 951                         FLAC__ASSERT(decoder->private_->last_frame.header.number_type == FLAC__FRAME_NUMBER_TYPE_SAMPLE_NUMBER);
 952                         if(this_frame_sample == last_frame_sample) {
 953                                 /* our last move backwards wasn't big enough */
 954                                 pos -= (last_pos - pos);
 955                                 needs_seek = true;
 956                         }
 957                         else {
 958                                 if(target_sample < this_frame_sample) {
 959                                         last_pos = pos;
 960                                         approx_bytes_per_frame = decoder->private_->last_frame.header.blocksize * channels * bps/8 + 64;
 961                                         pos -= approx_bytes_per_frame;
 962                                         needs_seek = true;
 963                                 }
 964                                 else { /* target_sample >= this_frame_sample + this frame's blocksize */
 965                                         FLAC__uint64 upos;
 966                                         if(decoder->private_->tell_callback(decoder, &upos, decoder->private_->client_data) != FLAC__SEEKABLE_STREAM_DECODER_TELL_STATUS_OK) {
 967                                                 decoder->protected_->state = FLAC__SEEKABLE_STREAM_DECODER_SEEK_ERROR;
 968                                                 return false;
 969                                         }
 970                                         last_pos = pos;
 971                                         pos = (FLAC__int32)upos;
 972                                         pos -= FLAC__stream_decoder_get_input_bytes_unconsumed(decoder->private_->stream_decoder);
 973                                         needs_seek = false;
 974                                 }
 975                         }
 976                         if(pos < (FLAC__int64)lower_bound)
 977                                 pos = (FLAC__int64)lower_bound;
 978                         last_frame_sample = this_frame_sample;
 979                 }
 980         }
 981
 982         return true;
 983 }