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 FLAC__StreamDecoderReadStatus read_callback_(const FLAC__StreamDecoder *decoder, FLAC__byte buffer[], unsigned *bytes, void *client_data);
  35 static FLAC__StreamDecoderWriteStatus write_callback_(const FLAC__StreamDecoder *decoder, const FLAC__Frame *frame, const FLAC__int32 *buffer[], void *client_data);
  36 static void metadata_callback_(const FLAC__StreamDecoder *decoder, const FLAC__StreamMetaData *metadata, void *client_data);
  37 static void error_callback_(const FLAC__StreamDecoder *decoder, FLAC__StreamDecoderErrorStatus status, void *client_data);
  38 static FLAC__bool seek_to_absolute_sample_(FLAC__SeekableStreamDecoder *decoder, FLAC__uint64 stream_length, FLAC__uint64 target_sample);
  39
  40 /***********************************************************************
  41  *
  42  * Private class data
  43  *
  44  ***********************************************************************/
  45
  46 typedef struct FLAC__SeekableStreamDecoderPrivate {
  47         FLAC__SeekableStreamDecoderReadStatus (*read_callback)(const FLAC__SeekableStreamDecoder *decoder, FLAC__byte buffer[], unsigned *bytes, void *client_data);
  48         FLAC__SeekableStreamDecoderSeekStatus (*seek_callback)(const FLAC__SeekableStreamDecoder *decoder, FLAC__uint64 absolute_byte_offset, void *client_data);
  49         FLAC__SeekableStreamDecoderTellStatus (*tell_callback)(const FLAC__SeekableStreamDecoder *decoder, FLAC__uint64 *absolute_byte_offset, void *client_data);
  50         FLAC__SeekableStreamDecoderLengthStatus (*length_callback)(const FLAC__SeekableStreamDecoder *decoder, FLAC__uint64 *stream_length, void *client_data);
  51         FLAC__bool (*eof_callback)(const FLAC__SeekableStreamDecoder *decoder, void *client_data);
  52         FLAC__StreamDecoderWriteStatus (*write_callback)(const FLAC__SeekableStreamDecoder *decoder, const FLAC__Frame *frame, const FLAC__int32 *buffer[], void *client_data);
  53         void (*metadata_callback)(const FLAC__SeekableStreamDecoder *decoder, const FLAC__StreamMetaData *metadata, void *client_data);
  54         void (*error_callback)(const FLAC__SeekableStreamDecoder *decoder, FLAC__StreamDecoderErrorStatus status, void *client_data);
  55         void *client_data;
  56         FLAC__StreamDecoder *stream_decoder;
  57         struct MD5Context md5context;
  58         FLAC__byte stored_md5sum[16]; /* this is what is stored in the metadata */
  59         FLAC__byte computed_md5sum[16]; /* this is the sum we computed from the decoded data */
  60         /* the rest of these are only used for seeking: */
  61         FLAC__StreamMetaData_StreamInfo stream_info; /* we keep this around so we can figure out how to seek quickly */
  62         const FLAC__StreamMetaData_SeekTable *seek_table; /* we hold a pointer to the stream decoder's seek table for the same reason */
  63         FLAC__Frame last_frame; /* holds the info of the last frame we seeked to */
  64         FLAC__uint64 target_sample;
  65 } FLAC__SeekableStreamDecoderPrivate;
  66
  67 /***********************************************************************
  68  *
  69  * Public static class data
  70  *
  71  ***********************************************************************/
  72
  73 const char *FLAC__SeekableStreamDecoderStateString[] = {
  74         "FLAC__SEEKABLE_STREAM_DECODER_OK",
  75         "FLAC__SEEKABLE_STREAM_DECODER_SEEKING",
  76         "FLAC__SEEKABLE_STREAM_DECODER_END_OF_STREAM",
  77         "FLAC__SEEKABLE_STREAM_DECODER_MEMORY_ALLOCATION_ERROR",
  78         "FLAC__SEEKABLE_STREAM_DECODER_STREAM_ERROR",
  79         "FLAC__SEEKABLE_STREAM_DECODER_READ_ERROR",
  80         "FLAC__SEEKABLE_STREAM_DECODER_SEEK_ERROR",
  81     "FLAC__SEEKABLE_STREAM_DECODER_ALREADY_INITIALIZED",
  82     "FLAC__SEEKABLE_STREAM_DECODER_INVALID_CALLBACK",
  83     "FLAC__SEEKABLE_STREAM_DECODER_UNINITIALIZED"
  84 };
  85
  86 const char *FLAC__SeekableStreamDecoderReadStatusString[] = {
  87         "FLAC__STREAM_DECODER_READ_STATUS_OK",
  88         "FLAC__STREAM_DECODER_READ_STATUS_ERROR"
  89 };
  90
  91 const char *FLAC__SeekableStreamDecoderSeekStatusString[] = {
  92         "FLAC__STREAM_DECODER_SEEK_STATUS_OK",
  93         "FLAC__STREAM_DECODER_SEEK_STATUS_ERROR"
  94 };
  95
  96 const char *FLAC__SeekableStreamDecoderTellStatusString[] = {
  97         "FLAC__STREAM_DECODER_TELL_STATUS_OK",
  98         "FLAC__STREAM_DECODER_TELL_STATUS_ERROR"
  99 };
 100
 101 const char *FLAC__SeekableStreamDecoderLengthStatusString[] = {
 102         "FLAC__STREAM_DECODER_LENGTH_STATUS_OK",
 103         "FLAC__STREAM_DECODER_LENGTH_STATUS_ERROR"
 104 };
 105
 106 /***********************************************************************
 107  *
 108  * Class constructor/destructor
 109  *
 110  ***********************************************************************/
 111
 112 FLAC__SeekableStreamDecoder *FLAC__seekable_stream_decoder_new()
 113 {
 114         FLAC__SeekableStreamDecoder *decoder;
 115
 116         FLAC__ASSERT(sizeof(int) >= 4); /* we want to die right away if this is not true */
 117
 118         decoder = (FLAC__SeekableStreamDecoder*)malloc(sizeof(FLAC__SeekableStreamDecoder));
 119         if(decoder == 0) {
 120                 return 0;
 121         }
 122         decoder->protected_ = (FLAC__SeekableStreamDecoderProtected*)malloc(sizeof(FLAC__SeekableStreamDecoderProtected));
 123         if(decoder->protected_ == 0) {
 124                 free(decoder);
 125                 return 0;
 126         }
 127         decoder->private_ = (FLAC__SeekableStreamDecoderPrivate*)malloc(sizeof(FLAC__SeekableStreamDecoderPrivate));
 128         if(decoder->private_ == 0) {
 129                 free(decoder->protected_);
 130                 free(decoder);
 131                 return 0;
 132         }
 133
 134         decoder->protected_->state = FLAC__SEEKABLE_STREAM_DECODER_UNINITIALIZED;
 135
 136         decoder->private_->read_callback = 0;
 137         decoder->private_->seek_callback = 0;
 138         decoder->private_->tell_callback = 0;
 139         decoder->private_->length_callback = 0;
 140         decoder->private_->eof_callback = 0;
 141         decoder->private_->write_callback = 0;
 142         decoder->private_->metadata_callback = 0;
 143         decoder->private_->error_callback = 0;
 144         decoder->private_->client_data = 0;
 145
 146         return decoder;
 147 }
 148
 149 void FLAC__seekable_stream_decoder_delete(FLAC__SeekableStreamDecoder *decoder)
 150 {
 151         FLAC__ASSERT(decoder != 0);
 152         FLAC__ASSERT(decoder->protected_ != 0);
 153         FLAC__ASSERT(decoder->private_ != 0);
 154
 155         free(decoder->private_);
 156         free(decoder->protected_);
 157         free(decoder);
 158 }
 159
 160 /***********************************************************************
 161  *
 162  * Public class methods
 163  *
 164  ***********************************************************************/
 165
 166 FLAC__SeekableStreamDecoderState FLAC__seekable_stream_decoder_init(FLAC__SeekableStreamDecoder *decoder)
 167 {
 168         FLAC__ASSERT(decoder != 0);
 169
 170         if(decoder->protected_->state != FLAC__SEEKABLE_STREAM_DECODER_UNINITIALIZED)
 171                 return decoder->protected_->state = FLAC__SEEKABLE_STREAM_DECODER_ALREADY_INITIALIZED;
 172
 173         decoder->protected_->state = FLAC__SEEKABLE_STREAM_DECODER_OK;
 174
 175         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)
 176                 return decoder->protected_->state = FLAC__SEEKABLE_STREAM_DECODER_INVALID_CALLBACK;
 177
 178         if(0 == decoder->private_->write_callback || 0 == decoder->private_->metadata_callback || 0 == decoder->private_->error_callback)
 179                 return decoder->protected_->state = FLAC__SEEKABLE_STREAM_DECODER_INVALID_CALLBACK;
 180
 181         decoder->private_->stream_decoder = 0;
 182         decoder->private_->seek_table = 0;
 183
 184         /* We initialize the MD5Context even though we may never use it.  This is
 185          * because md5_checking may be turned on to start and then turned off if a
 186          * seek occurs.  So we always init the context here and finalize it in
 187          * FLAC__seekable_stream_decoder_finish() to make sure things are always
 188          * cleaned up properly.
 189          */
 190         MD5Init(&decoder->private_->md5context);
 191
 192         decoder->private_->stream_decoder = FLAC__stream_decoder_new();
 193
 194         if(0 == decoder->private_->stream_decoder)
 195                 return decoder->protected_->state = FLAC__SEEKABLE_STREAM_DECODER_MEMORY_ALLOCATION_ERROR;
 196
 197         FLAC__stream_decoder_set_read_callback(decoder->private_->stream_decoder, read_callback_);
 198         FLAC__stream_decoder_set_write_callback(decoder->private_->stream_decoder, write_callback_);
 199         FLAC__stream_decoder_set_metadata_callback(decoder->private_->stream_decoder, metadata_callback_);
 200         FLAC__stream_decoder_set_error_callback(decoder->private_->stream_decoder, error_callback_);
 201         FLAC__stream_decoder_set_client_data(decoder->private_->stream_decoder, decoder);
 202
 203         if(FLAC__stream_decoder_init(decoder->private_->stream_decoder) != FLAC__STREAM_DECODER_SEARCH_FOR_METADATA)
 204                 return decoder->protected_->state = FLAC__SEEKABLE_STREAM_DECODER_STREAM_ERROR;
 205
 206         return decoder->protected_->state;
 207 }
 208
 209 FLAC__bool FLAC__seekable_stream_decoder_finish(FLAC__SeekableStreamDecoder *decoder)
 210 {
 211         FLAC__bool md5_failed = false;
 212
 213         FLAC__ASSERT(decoder != 0);
 214         if(decoder->protected_->state == FLAC__SEEKABLE_STREAM_DECODER_UNINITIALIZED)
 215                 return true;
 216         /* see the comment in FLAC__seekable_stream_decoder_init() as to why we
 217          * always call MD5Final()
 218          */
 219         MD5Final(decoder->private_->computed_md5sum, &decoder->private_->md5context);
 220         if(decoder->private_->stream_decoder != 0) {
 221                 FLAC__stream_decoder_finish(decoder->private_->stream_decoder);
 222                 FLAC__stream_decoder_delete(decoder->private_->stream_decoder);
 223         }
 224         if(decoder->protected_->md5_checking) {
 225                 if(memcmp(decoder->private_->stored_md5sum, decoder->private_->computed_md5sum, 16))
 226                         md5_failed = true;
 227         }
 228         decoder->protected_->state = FLAC__SEEKABLE_STREAM_DECODER_UNINITIALIZED;
 229         return !md5_failed;
 230 }
 231
 232 FLAC__bool FLAC__seekable_stream_decoder_set_md5_checking(const FLAC__SeekableStreamDecoder *decoder, FLAC__bool value)
 233 {
 234         if(decoder->protected_->state != FLAC__SEEKABLE_STREAM_DECODER_UNINITIALIZED)
 235                 return false;
 236         decoder->protected_->md5_checking = value;
 237         return true;
 238 }
 239
 240 FLAC__bool FLAC__seekable_stream_decoder_set_read_callback(const FLAC__SeekableStreamDecoder *decoder, FLAC__SeekableStreamDecoderReadStatus (*value)(const FLAC__SeekableStreamDecoder *decoder, FLAC__byte buffer[], unsigned *bytes, void *client_data))
 241 {
 242         if(decoder->protected_->state != FLAC__SEEKABLE_STREAM_DECODER_UNINITIALIZED)
 243                 return false;
 244         decoder->private_->read_callback = value;
 245         return true;
 246 }
 247
 248 FLAC__bool FLAC__seekable_stream_decoder_set_seek_callback(const FLAC__SeekableStreamDecoder *decoder, FLAC__SeekableStreamDecoderSeekStatus (*value)(const FLAC__SeekableStreamDecoder *decoder, FLAC__uint64 absolute_byte_offset, void *client_data))
 249 {
 250         if(decoder->protected_->state != FLAC__SEEKABLE_STREAM_DECODER_UNINITIALIZED)
 251                 return false;
 252         decoder->private_->seek_callback = value;
 253         return true;
 254 }
 255
 256 FLAC__bool FLAC__seekable_stream_decoder_set_tell_callback(const FLAC__SeekableStreamDecoder *decoder, FLAC__SeekableStreamDecoderTellStatus (*value)(const FLAC__SeekableStreamDecoder *decoder, FLAC__uint64 *absolute_byte_offset, void *client_data))
 257 {
 258         if(decoder->protected_->state != FLAC__SEEKABLE_STREAM_DECODER_UNINITIALIZED)
 259                 return false;
 260         decoder->private_->tell_callback = value;
 261         return true;
 262 }
 263
 264 FLAC__bool FLAC__seekable_stream_decoder_set_length_callback(const FLAC__SeekableStreamDecoder *decoder, FLAC__SeekableStreamDecoderLengthStatus (*value)(const FLAC__SeekableStreamDecoder *decoder, FLAC__uint64 *stream_length, void *client_data))
 265 {
 266         if(decoder->protected_->state != FLAC__SEEKABLE_STREAM_DECODER_UNINITIALIZED)
 267                 return false;
 268         decoder->private_->length_callback = value;
 269         return true;
 270 }
 271
 272 FLAC__bool FLAC__seekable_stream_decoder_set_eof_callback(const FLAC__SeekableStreamDecoder *decoder, FLAC__bool (*value)(const FLAC__SeekableStreamDecoder *decoder, void *client_data))
 273 {
 274         if(decoder->protected_->state != FLAC__SEEKABLE_STREAM_DECODER_UNINITIALIZED)
 275                 return false;
 276         decoder->private_->eof_callback = value;
 277         return true;
 278 }
 279
 280 FLAC__bool FLAC__seekable_stream_decoder_set_write_callback(const FLAC__SeekableStreamDecoder *decoder, FLAC__StreamDecoderWriteStatus (*value)(const FLAC__SeekableStreamDecoder *decoder, const FLAC__Frame *frame, const FLAC__int32 *buffer[], void *client_data))
 281 {
 282         if(decoder->protected_->state != FLAC__SEEKABLE_STREAM_DECODER_UNINITIALIZED)
 283                 return false;
 284         decoder->private_->write_callback = value;
 285         return true;
 286 }
 287
 288 FLAC__bool FLAC__seekable_stream_decoder_set_metadata_callback(const FLAC__SeekableStreamDecoder *decoder, void (*value)(const FLAC__SeekableStreamDecoder *decoder, const FLAC__StreamMetaData *metadata, void *client_data))
 289 {
 290         if(decoder->protected_->state != FLAC__SEEKABLE_STREAM_DECODER_UNINITIALIZED)
 291                 return false;
 292         decoder->private_->metadata_callback = value;
 293         return true;
 294 }
 295
 296 FLAC__bool FLAC__seekable_stream_decoder_set_error_callback(const FLAC__SeekableStreamDecoder *decoder, void (*value)(const FLAC__SeekableStreamDecoder *decoder, FLAC__StreamDecoderErrorStatus status, void *client_data))
 297 {
 298         if(decoder->protected_->state != FLAC__SEEKABLE_STREAM_DECODER_UNINITIALIZED)
 299                 return false;
 300         decoder->private_->error_callback = value;
 301         return true;
 302 }
 303
 304 FLAC__bool FLAC__seekable_stream_decoder_set_client_data(const FLAC__SeekableStreamDecoder *decoder, void *value)
 305 {
 306         if(decoder->protected_->state != FLAC__SEEKABLE_STREAM_DECODER_UNINITIALIZED)
 307                 return false;
 308         decoder->private_->client_data = value;
 309         return true;
 310 }
 311
 312 FLAC__SeekableStreamDecoderState FLAC__seekable_stream_decoder_get_state(const FLAC__SeekableStreamDecoder *decoder)
 313 {
 314         return decoder->protected_->state;
 315 }
 316
 317 FLAC__bool FLAC__seekable_stream_decoder_get_md5_checking(const FLAC__SeekableStreamDecoder *decoder)
 318 {
 319         return decoder->protected_->md5_checking;
 320 }
 321
 322 FLAC__bool FLAC__seekable_stream_decoder_process_whole_stream(FLAC__SeekableStreamDecoder *decoder)
 323 {
 324         FLAC__bool ret;
 325         FLAC__ASSERT(decoder != 0);
 326
 327         if(decoder->private_->stream_decoder->protected_->state == FLAC__STREAM_DECODER_END_OF_STREAM)
 328                 decoder->protected_->state = FLAC__SEEKABLE_STREAM_DECODER_END_OF_STREAM;
 329
 330         if(decoder->protected_->state == FLAC__SEEKABLE_STREAM_DECODER_END_OF_STREAM)
 331                 return true;
 332
 333         FLAC__ASSERT(decoder->protected_->state == FLAC__SEEKABLE_STREAM_DECODER_OK);
 334
 335         ret = FLAC__stream_decoder_process_whole_stream(decoder->private_->stream_decoder);
 336         if(!ret)
 337                 decoder->protected_->state = FLAC__SEEKABLE_STREAM_DECODER_STREAM_ERROR;
 338
 339         return ret;
 340 }
 341
 342 FLAC__bool FLAC__seekable_stream_decoder_process_metadata(FLAC__SeekableStreamDecoder *decoder)
 343 {
 344         FLAC__bool ret;
 345         FLAC__ASSERT(decoder != 0);
 346
 347         if(decoder->private_->stream_decoder->protected_->state == FLAC__STREAM_DECODER_END_OF_STREAM)
 348                 decoder->protected_->state = FLAC__SEEKABLE_STREAM_DECODER_END_OF_STREAM;
 349
 350         if(decoder->protected_->state == FLAC__SEEKABLE_STREAM_DECODER_END_OF_STREAM)
 351                 return true;
 352
 353         FLAC__ASSERT(decoder->protected_->state == FLAC__SEEKABLE_STREAM_DECODER_OK);
 354
 355         ret = FLAC__stream_decoder_process_metadata(decoder->private_->stream_decoder);
 356         if(!ret)
 357                 decoder->protected_->state = FLAC__SEEKABLE_STREAM_DECODER_STREAM_ERROR;
 358
 359         return ret;
 360 }
 361
 362 FLAC__bool FLAC__seekable_stream_decoder_process_one_frame(FLAC__SeekableStreamDecoder *decoder)
 363 {
 364         FLAC__bool ret;
 365         FLAC__ASSERT(decoder != 0);
 366
 367         if(decoder->private_->stream_decoder->protected_->state == FLAC__STREAM_DECODER_END_OF_STREAM)
 368                 decoder->protected_->state = FLAC__SEEKABLE_STREAM_DECODER_END_OF_STREAM;
 369
 370         if(decoder->protected_->state == FLAC__SEEKABLE_STREAM_DECODER_END_OF_STREAM)
 371                 return true;
 372
 373         FLAC__ASSERT(decoder->protected_->state == FLAC__SEEKABLE_STREAM_DECODER_OK);
 374
 375         ret = FLAC__stream_decoder_process_one_frame(decoder->private_->stream_decoder);
 376         if(!ret)
 377                 decoder->protected_->state = FLAC__SEEKABLE_STREAM_DECODER_STREAM_ERROR;
 378
 379         return ret;
 380 }
 381
 382 FLAC__bool FLAC__seekable_stream_decoder_process_remaining_frames(FLAC__SeekableStreamDecoder *decoder)
 383 {
 384         FLAC__bool ret;
 385         FLAC__ASSERT(decoder != 0);
 386
 387         if(decoder->private_->stream_decoder->protected_->state == FLAC__STREAM_DECODER_END_OF_STREAM)
 388                 decoder->protected_->state = FLAC__SEEKABLE_STREAM_DECODER_END_OF_STREAM;
 389
 390         if(decoder->protected_->state == FLAC__SEEKABLE_STREAM_DECODER_END_OF_STREAM)
 391                 return true;
 392
 393         FLAC__ASSERT(decoder->protected_->state == FLAC__SEEKABLE_STREAM_DECODER_OK);
 394
 395         ret = FLAC__stream_decoder_process_remaining_frames(decoder->private_->stream_decoder);
 396         if(!ret)
 397                 decoder->protected_->state = FLAC__SEEKABLE_STREAM_DECODER_STREAM_ERROR;
 398
 399         return ret;
 400 }
 401
 402 FLAC__bool FLAC__seekable_stream_decoder_seek_absolute(FLAC__SeekableStreamDecoder *decoder, FLAC__uint64 sample)
 403 {
 404         FLAC__uint64 length;
 405
 406         FLAC__ASSERT(decoder != 0);
 407         FLAC__ASSERT(decoder->protected_->state == FLAC__SEEKABLE_STREAM_DECODER_OK);
 408
 409         decoder->protected_->state = FLAC__SEEKABLE_STREAM_DECODER_SEEKING;
 410
 411         /* turn off md5 checking if a seek is attempted */
 412         decoder->protected_->md5_checking = false;
 413
 414         if(!FLAC__stream_decoder_reset(decoder->private_->stream_decoder)) {
 415                 decoder->protected_->state = FLAC__SEEKABLE_STREAM_DECODER_STREAM_ERROR;
 416                 return false;
 417         }
 418         /* get the file length */
 419         if(decoder->private_->length_callback(decoder, &length, decoder->private_->client_data) != FLAC__SEEKABLE_STREAM_DECODER_LENGTH_STATUS_OK) {
 420                 decoder->protected_->state = FLAC__SEEKABLE_STREAM_DECODER_SEEK_ERROR;
 421                 return false;
 422         }
 423         /* rewind */
 424         if(decoder->private_->seek_callback(decoder, 0, decoder->private_->client_data) != FLAC__SEEKABLE_STREAM_DECODER_SEEK_STATUS_OK) {
 425                 decoder->protected_->state = FLAC__SEEKABLE_STREAM_DECODER_SEEK_ERROR;
 426                 return false;
 427         }
 428         if(!FLAC__stream_decoder_process_metadata(decoder->private_->stream_decoder)) {
 429                 decoder->protected_->state = FLAC__SEEKABLE_STREAM_DECODER_STREAM_ERROR;
 430                 return false;
 431         }
 432         if(sample > decoder->private_->stream_info.total_samples) {
 433                 decoder->protected_->state = FLAC__SEEKABLE_STREAM_DECODER_SEEK_ERROR;
 434                 return false;
 435         }
 436
 437         return seek_to_absolute_sample_(decoder, length, sample);
 438 }
 439
 440 /***********************************************************************
 441  *
 442  * Private class methods
 443  *
 444  ***********************************************************************/
 445
 446 FLAC__StreamDecoderReadStatus read_callback_(const FLAC__StreamDecoder *decoder, FLAC__byte buffer[], unsigned *bytes, void *client_data)
 447 {
 448         FLAC__SeekableStreamDecoder *seekable_stream_decoder = (FLAC__SeekableStreamDecoder *)client_data;
 449         (void)decoder;
 450         if(seekable_stream_decoder->private_->eof_callback(seekable_stream_decoder, seekable_stream_decoder->private_->client_data)) {
 451                 seekable_stream_decoder->protected_->state = FLAC__SEEKABLE_STREAM_DECODER_END_OF_STREAM;
 452                 return FLAC__STREAM_DECODER_READ_END_OF_STREAM;
 453         }
 454         else if(*bytes > 0) {
 455                 unsigned bytes_read = *bytes;
 456                 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) {
 457                         seekable_stream_decoder->protected_->state = FLAC__SEEKABLE_STREAM_DECODER_READ_ERROR;
 458                         return FLAC__STREAM_DECODER_READ_ABORT;
 459                 }
 460                 if(bytes_read == 0) {
 461                         if(seekable_stream_decoder->private_->eof_callback(seekable_stream_decoder, seekable_stream_decoder->private_->client_data)) {
 462                                 seekable_stream_decoder->protected_->state = FLAC__SEEKABLE_STREAM_DECODER_END_OF_STREAM;
 463                                 return FLAC__STREAM_DECODER_READ_END_OF_STREAM;
 464                         }
 465                         else
 466                                 return FLAC__STREAM_DECODER_READ_CONTINUE;
 467                 }
 468                 else {
 469                         *bytes = bytes_read;
 470                         return FLAC__STREAM_DECODER_READ_CONTINUE;
 471                 }
 472         }
 473         else
 474                 return FLAC__STREAM_DECODER_READ_ABORT; /* abort to avoid a deadlock */
 475 }
 476
 477 FLAC__StreamDecoderWriteStatus write_callback_(const FLAC__StreamDecoder *decoder, const FLAC__Frame *frame, const FLAC__int32 *buffer[], void *client_data)
 478 {
 479         FLAC__SeekableStreamDecoder *seekable_stream_decoder = (FLAC__SeekableStreamDecoder *)client_data;
 480         (void)decoder;
 481
 482         if(seekable_stream_decoder->protected_->state == FLAC__SEEKABLE_STREAM_DECODER_SEEKING) {
 483                 FLAC__uint64 this_frame_sample = frame->header.number.sample_number;
 484                 FLAC__uint64 next_frame_sample = this_frame_sample + (FLAC__uint64)frame->header.blocksize;
 485                 FLAC__uint64 target_sample = seekable_stream_decoder->private_->target_sample;
 486
 487                 FLAC__ASSERT(frame->header.number_type == FLAC__FRAME_NUMBER_TYPE_SAMPLE_NUMBER);
 488
 489                 seekable_stream_decoder->private_->last_frame = *frame; /* save the frame */
 490                 if(this_frame_sample <= target_sample && target_sample < next_frame_sample) { /* we hit our target frame */
 491                         unsigned delta = (unsigned)(target_sample - this_frame_sample);
 492                         /* kick out of seek mode */
 493                         seekable_stream_decoder->protected_->state = FLAC__SEEKABLE_STREAM_DECODER_OK;
 494                         /* shift out the samples before target_sample */
 495                         if(delta > 0) {
 496                                 unsigned channel;
 497                                 const FLAC__int32 *newbuffer[FLAC__MAX_CHANNELS];
 498                                 for(channel = 0; channel < frame->header.channels; channel++)
 499                                         newbuffer[channel] = buffer[channel] + delta;
 500                                 seekable_stream_decoder->private_->last_frame.header.blocksize -= delta;
 501                                 seekable_stream_decoder->private_->last_frame.header.number.sample_number += (FLAC__uint64)delta;
 502                                 /* write the relevant samples */
 503                                 return seekable_stream_decoder->private_->write_callback(seekable_stream_decoder, &seekable_stream_decoder->private_->last_frame, newbuffer, seekable_stream_decoder->private_->client_data);
 504                         }
 505                         else {
 506                                 /* write the relevant samples */
 507                                 return seekable_stream_decoder->private_->write_callback(seekable_stream_decoder, frame, buffer, seekable_stream_decoder->private_->client_data);
 508                         }
 509                 }
 510                 else {
 511                         return FLAC__STREAM_DECODER_WRITE_CONTINUE;
 512                 }
 513         }
 514         else {
 515                 if(seekable_stream_decoder->protected_->md5_checking) {
 516                         if(!FLAC__MD5Accumulate(&seekable_stream_decoder->private_->md5context, buffer, frame->header.channels, frame->header.blocksize, (frame->header.bits_per_sample+7) / 8))
 517                                 return FLAC__STREAM_DECODER_WRITE_ABORT;
 518                 }
 519                 return seekable_stream_decoder->private_->write_callback(seekable_stream_decoder, frame, buffer, seekable_stream_decoder->private_->client_data);
 520         }
 521 }
 522
 523 void metadata_callback_(const FLAC__StreamDecoder *decoder, const FLAC__StreamMetaData *metadata, void *client_data)
 524 {
 525         FLAC__SeekableStreamDecoder *seekable_stream_decoder = (FLAC__SeekableStreamDecoder *)client_data;
 526         (void)decoder;
 527
 528         if(metadata->type == FLAC__METADATA_TYPE_STREAMINFO) {
 529                 seekable_stream_decoder->private_->stream_info = metadata->data.stream_info;
 530                 /* save the MD5 signature for comparison later */
 531                 memcpy(seekable_stream_decoder->private_->stored_md5sum, metadata->data.stream_info.md5sum, 16);
 532                 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))
 533                         seekable_stream_decoder->protected_->md5_checking = false;
 534         }
 535         else if(metadata->type == FLAC__METADATA_TYPE_SEEKTABLE) {
 536                 seekable_stream_decoder->private_->seek_table = &metadata->data.seek_table;
 537         }
 538
 539         if(seekable_stream_decoder->protected_->state != FLAC__SEEKABLE_STREAM_DECODER_SEEKING)
 540                 seekable_stream_decoder->private_->metadata_callback(seekable_stream_decoder, metadata, seekable_stream_decoder->private_->client_data);
 541 }
 542
 543 void error_callback_(const FLAC__StreamDecoder *decoder, FLAC__StreamDecoderErrorStatus status, void *client_data)
 544 {
 545         FLAC__SeekableStreamDecoder *seekable_stream_decoder = (FLAC__SeekableStreamDecoder *)client_data;
 546         (void)decoder;
 547
 548         if(seekable_stream_decoder->protected_->state != FLAC__SEEKABLE_STREAM_DECODER_SEEKING)
 549                 seekable_stream_decoder->private_->error_callback(seekable_stream_decoder, status, seekable_stream_decoder->private_->client_data);
 550 }
 551
 552 FLAC__bool seek_to_absolute_sample_(FLAC__SeekableStreamDecoder *decoder, FLAC__uint64 stream_length, FLAC__uint64 target_sample)
 553 {
 554         FLAC__uint64 first_frame_offset, lower_bound, upper_bound;
 555         FLAC__int64 pos = -1, last_pos = -1;
 556         int i, lower_seek_point = -1, upper_seek_point = -1;
 557         unsigned approx_bytes_per_frame;
 558         FLAC__uint64 last_frame_sample = 0xffffffffffffffff;
 559         FLAC__bool needs_seek;
 560         const FLAC__bool is_variable_blocksize_stream = (decoder->private_->stream_info.min_blocksize != decoder->private_->stream_info.max_blocksize);
 561
 562         /* we are just guessing here, but we want to guess high, not low */
 563         if(decoder->private_->stream_info.max_framesize > 0) {
 564                 approx_bytes_per_frame = decoder->private_->stream_info.max_framesize;
 565         }
 566         else if(!is_variable_blocksize_stream) {
 567                 /* note there are no () around 'decoder->private_->stream_info.bits_per_sample/8' to keep precision up since it's an integer calulation */
 568                 approx_bytes_per_frame = decoder->private_->stream_info.min_blocksize * decoder->private_->stream_info.channels * decoder->private_->stream_info.bits_per_sample/8 + 64;
 569         }
 570         else
 571                 approx_bytes_per_frame = 1152 * decoder->private_->stream_info.channels * decoder->private_->stream_info.bits_per_sample/8 + 64;
 572
 573         /*
 574          * The stream position is currently at the first frame plus any read
 575          * ahead data, so first we get the stream position, then subtract
 576          * uncomsumed bytes to get the position of the first frame in the
 577          * stream.
 578          */
 579         if(decoder->private_->tell_callback(decoder, &first_frame_offset, decoder->private_->client_data) != FLAC__SEEKABLE_STREAM_DECODER_TELL_STATUS_OK) {
 580                 decoder->protected_->state = FLAC__SEEKABLE_STREAM_DECODER_SEEK_ERROR;
 581                 return false;
 582         }
 583         FLAC__ASSERT(first_frame_offset >= FLAC__stream_decoder_get_input_bytes_unconsumed(decoder->private_->stream_decoder));
 584         first_frame_offset -= FLAC__stream_decoder_get_input_bytes_unconsumed(decoder->private_->stream_decoder);
 585
 586         /*
 587          * First, we set an upper and lower bound on where in the
 588          * stream we will search.  For now we assume the worst case
 589          * scenario, which is our best guess at the beginning of
 590          * the first and last frames.
 591          */
 592         lower_bound = first_frame_offset;
 593
 594         /* calc the upper_bound, beyond which we never want to seek */
 595         if(decoder->private_->stream_info.max_framesize > 0)
 596                 upper_bound = stream_length - (decoder->private_->stream_info.max_framesize + 128 + 2); /* 128 for a possible ID3V1 tag, 2 for indexing differences */
 597         else
 598                 upper_bound = stream_length - ((decoder->private_->stream_info.channels * decoder->private_->stream_info.bits_per_sample * FLAC__MAX_BLOCK_SIZE) / 8 + 128 + 2);
 599
 600         /*
 601          * Now we refine the bounds if we have a seektable with
 602          * suitable points.  Note that according to the spec they
 603          * must be ordered by ascending sample number.
 604          */
 605         if(0 != decoder->private_->seek_table) {
 606                 /* find the closest seek point <= target_sample, if it exists */
 607                 for(i = (int)decoder->private_->seek_table->num_points - 1; i >= 0; i--) {
 608                         if(decoder->private_->seek_table->points[i].sample_number != FLAC__STREAM_METADATA_SEEKPOINT_PLACEHOLDER && decoder->private_->seek_table->points[i].sample_number <= target_sample)
 609                                 break;
 610                 }
 611                 if(i >= 0) { /* i.e. we found a suitable seek point... */
 612                         lower_bound = first_frame_offset + decoder->private_->seek_table->points[i].stream_offset;
 613                         lower_seek_point = i;
 614                 }
 615
 616                 /* find the closest seek point > target_sample, if it exists */
 617                 for(i = 0; i < (int)decoder->private_->seek_table->num_points; i++) {
 618                         if(decoder->private_->seek_table->points[i].sample_number != FLAC__STREAM_METADATA_SEEKPOINT_PLACEHOLDER && decoder->private_->seek_table->points[i].sample_number > target_sample)
 619                                 break;
 620                 }
 621                 if(i < (int)decoder->private_->seek_table->num_points) { /* i.e. we found a suitable seek point... */
 622                         upper_bound = first_frame_offset + decoder->private_->seek_table->points[i].stream_offset;
 623                         upper_seek_point = i;
 624                 }
 625         }
 626
 627         /*
 628          * Now guess at where within those bounds our target
 629          * sample will be.
 630          */
 631         if(lower_seek_point >= 0) {
 632                 /* first see if our sample is within a few frames of the lower seekpoint */
 633                 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)) {
 634                         pos = (FLAC__int64)lower_bound;
 635                 }
 636                 else if(upper_seek_point >= 0) {
 637                         const FLAC__uint64 target_offset = target_sample - decoder->private_->seek_table->points[lower_seek_point].sample_number;
 638                         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;
 639                         const FLAC__uint64 range_bytes = upper_bound - lower_bound;
 640 #if defined _MSC_VER || defined __MINGW32__
 641                         /* with VC++ you have to spoon feed it the casting */
 642                         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;
 643 #else
 644                         pos = (FLAC__int64)lower_bound + (FLAC__int64)((double)target_offset / (double)range_samples * (double)(range_bytes-1)) - approx_bytes_per_frame;
 645 #endif
 646                 }
 647         }
 648         if(pos < 0) {
 649                 /* We need to use the metadata and the filelength to estimate the position of the frame with the correct sample */
 650 #if defined _MSC_VER || defined __MINGW32__
 651                 /* with VC++ you have to spoon feed it the casting */
 652                 pos = (FLAC__int64)first_frame_offset + (FLAC__int64)((double)(FLAC__int64)target_sample / (double)(FLAC__int64)decoder->private_->stream_info.total_samples * (double)(FLAC__int64)(stream_length-first_frame_offset-1)) - approx_bytes_per_frame;
 653 #else
 654                 pos = (FLAC__int64)first_frame_offset + (FLAC__int64)((double)target_sample / (double)decoder->private_->stream_info.total_samples * (double)(stream_length-first_frame_offset-1)) - approx_bytes_per_frame;
 655 #endif
 656         }
 657
 658         /* clip the position to the bounds, lower bound takes precedence */
 659         if(pos >= (FLAC__int64)upper_bound)
 660                 pos = (FLAC__int64)upper_bound-1;
 661         if(pos < (FLAC__int64)lower_bound)
 662                 pos = (FLAC__int64)lower_bound;
 663         needs_seek = true;
 664
 665         decoder->private_->target_sample = target_sample;
 666         while(1) {
 667                 if(needs_seek) {
 668                         if(decoder->private_->seek_callback(decoder, (FLAC__uint64)pos, decoder->private_->client_data) != FLAC__SEEKABLE_STREAM_DECODER_SEEK_STATUS_OK) {
 669                                 decoder->protected_->state = FLAC__SEEKABLE_STREAM_DECODER_SEEK_ERROR;
 670                                 return false;
 671                         }
 672                         if(!FLAC__stream_decoder_flush(decoder->private_->stream_decoder)) {
 673                                 decoder->protected_->state = FLAC__SEEKABLE_STREAM_DECODER_STREAM_ERROR;
 674                                 return false;
 675                         }
 676                 }
 677                 if(!FLAC__stream_decoder_process_one_frame(decoder->private_->stream_decoder)) {
 678                         decoder->protected_->state = FLAC__SEEKABLE_STREAM_DECODER_SEEK_ERROR;
 679                         return false;
 680                 }
 681                 /* our write callback will change the state when it gets to the target frame */
 682                 if(decoder->protected_->state != FLAC__SEEKABLE_STREAM_DECODER_SEEKING) {
 683                         break;
 684                 }
 685                 else { /* we need to narrow the search */
 686                         FLAC__uint64 this_frame_sample = decoder->private_->last_frame.header.number.sample_number;
 687                         FLAC__ASSERT(decoder->private_->last_frame.header.number_type == FLAC__FRAME_NUMBER_TYPE_SAMPLE_NUMBER);
 688                         if(this_frame_sample == last_frame_sample) {
 689                                 /* our last move backwards wasn't big enough */
 690                                 pos -= (last_pos - pos);
 691                                 needs_seek = true;
 692                         }
 693                         else {
 694                                 if(target_sample < this_frame_sample) {
 695                                         last_pos = pos;
 696                                         approx_bytes_per_frame = decoder->private_->last_frame.header.blocksize * decoder->private_->last_frame.header.channels * decoder->private_->last_frame.header.bits_per_sample/8 + 64;
 697                                         pos -= approx_bytes_per_frame;
 698                                         needs_seek = true;
 699                                 }
 700                                 else { /* target_sample >= this_frame_sample + this frame's blocksize */
 701                                         last_pos = pos;
 702                                         if(decoder->private_->tell_callback(decoder, (FLAC__uint64*)(&pos), decoder->private_->client_data) != FLAC__SEEKABLE_STREAM_DECODER_TELL_STATUS_OK) {
 703                                                 decoder->protected_->state = FLAC__SEEKABLE_STREAM_DECODER_SEEK_ERROR;
 704                                                 return false;
 705                                         }
 706                                         pos -= FLAC__stream_decoder_get_input_bytes_unconsumed(decoder->private_->stream_decoder);
 707                                         needs_seek = false;
 708                                 }
 709                         }
 710                         if(pos < (FLAC__int64)lower_bound)
 711                                 pos = (FLAC__int64)lower_bound;
 712                         last_frame_sample = this_frame_sample;
 713                 }
 714         }
 715
 716         return true;
 717 }