1 /* libFLAC - Free Lossless Audio Codec library
2 * Copyright (C) 2000,2001,2002 Josh Coalson
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.
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.
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.
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"
28 /***********************************************************************
30 * Private class method prototypes
32 ***********************************************************************/
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);
41 /***********************************************************************
45 ***********************************************************************/
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);
57 FLAC__StreamDecoder *stream_decoder;
58 FLAC__bool do_md5_checking; /* initially gets protected_->md5_checking but is turned off after a seek */
59 struct MD5Context md5context;
60 FLAC__byte stored_md5sum[16]; /* this is what is stored in the metadata */
61 FLAC__byte computed_md5sum[16]; /* this is the sum we computed from the decoded data */
62 /* the rest of these are only used for seeking: */
63 FLAC__StreamMetadata_StreamInfo stream_info; /* we keep this around so we can figure out how to seek quickly */
64 const FLAC__StreamMetadata_SeekTable *seek_table; /* we hold a pointer to the stream decoder's seek table for the same reason */
65 /* 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 */
66 FLAC__bool ignore_stream_info_block;
67 FLAC__bool ignore_seek_table_block;
68 FLAC__Frame last_frame; /* holds the info of the last frame we seeked to */
69 FLAC__uint64 target_sample;
70 } FLAC__SeekableStreamDecoderPrivate;
72 /***********************************************************************
74 * Public static class data
76 ***********************************************************************/
78 const char * const FLAC__SeekableStreamDecoderStateString[] = {
79 "FLAC__SEEKABLE_STREAM_DECODER_OK",
80 "FLAC__SEEKABLE_STREAM_DECODER_SEEKING",
81 "FLAC__SEEKABLE_STREAM_DECODER_END_OF_STREAM",
82 "FLAC__SEEKABLE_STREAM_DECODER_MEMORY_ALLOCATION_ERROR",
83 "FLAC__SEEKABLE_STREAM_DECODER_STREAM_DECODER_ERROR",
84 "FLAC__SEEKABLE_STREAM_DECODER_READ_ERROR",
85 "FLAC__SEEKABLE_STREAM_DECODER_SEEK_ERROR",
86 "FLAC__SEEKABLE_STREAM_DECODER_ALREADY_INITIALIZED",
87 "FLAC__SEEKABLE_STREAM_DECODER_INVALID_CALLBACK",
88 "FLAC__SEEKABLE_STREAM_DECODER_UNINITIALIZED"
91 const char * const FLAC__SeekableStreamDecoderReadStatusString[] = {
92 "FLAC__SEEKABLE_STREAM_DECODER_READ_STATUS_OK",
93 "FLAC__SEEKABLE_STREAM_DECODER_READ_STATUS_ERROR"
96 const char * const FLAC__SeekableStreamDecoderSeekStatusString[] = {
97 "FLAC__SEEKABLE_STREAM_DECODER_SEEK_STATUS_OK",
98 "FLAC__SEEKABLE_STREAM_DECODER_SEEK_STATUS_ERROR"
101 const char * const FLAC__SeekableStreamDecoderTellStatusString[] = {
102 "FLAC__SEEKABLE_STREAM_DECODER_TELL_STATUS_OK",
103 "FLAC__SEEKABLE_STREAM_DECODER_TELL_STATUS_ERROR"
106 const char * const FLAC__SeekableStreamDecoderLengthStatusString[] = {
107 "FLAC__SEEKABLE_STREAM_DECODER_LENGTH_STATUS_OK",
108 "FLAC__SEEKABLE_STREAM_DECODER_LENGTH_STATUS_ERROR"
111 /***********************************************************************
113 * Class constructor/destructor
115 ***********************************************************************/
117 FLAC__SeekableStreamDecoder *FLAC__seekable_stream_decoder_new()
119 FLAC__SeekableStreamDecoder *decoder;
121 FLAC__ASSERT(sizeof(int) >= 4); /* we want to die right away if this is not true */
123 decoder = (FLAC__SeekableStreamDecoder*)malloc(sizeof(FLAC__SeekableStreamDecoder));
127 decoder->protected_ = (FLAC__SeekableStreamDecoderProtected*)malloc(sizeof(FLAC__SeekableStreamDecoderProtected));
128 if(decoder->protected_ == 0) {
132 decoder->private_ = (FLAC__SeekableStreamDecoderPrivate*)malloc(sizeof(FLAC__SeekableStreamDecoderPrivate));
133 if(decoder->private_ == 0) {
134 free(decoder->protected_);
139 decoder->private_->stream_decoder = FLAC__stream_decoder_new();
141 if(0 == decoder->private_->stream_decoder) {
142 free(decoder->private_);
143 free(decoder->protected_);
148 seekable_stream_decoder_set_defaults_(decoder);
150 decoder->protected_->state = FLAC__SEEKABLE_STREAM_DECODER_UNINITIALIZED;
155 void FLAC__seekable_stream_decoder_delete(FLAC__SeekableStreamDecoder *decoder)
157 FLAC__ASSERT(decoder != 0);
158 FLAC__ASSERT(decoder->protected_ != 0);
159 FLAC__ASSERT(decoder->private_ != 0);
160 FLAC__ASSERT(decoder->private_->stream_decoder != 0);
162 (void)FLAC__seekable_stream_decoder_finish(decoder);
164 FLAC__stream_decoder_delete(decoder->private_->stream_decoder);
166 free(decoder->private_);
167 free(decoder->protected_);
171 /***********************************************************************
173 * Public class methods
175 ***********************************************************************/
177 FLAC__SeekableStreamDecoderState FLAC__seekable_stream_decoder_init(FLAC__SeekableStreamDecoder *decoder)
179 FLAC__ASSERT(decoder != 0);
181 if(decoder->protected_->state != FLAC__SEEKABLE_STREAM_DECODER_UNINITIALIZED)
182 return decoder->protected_->state = FLAC__SEEKABLE_STREAM_DECODER_ALREADY_INITIALIZED;
184 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)
185 return decoder->protected_->state = FLAC__SEEKABLE_STREAM_DECODER_INVALID_CALLBACK;
187 if(0 == decoder->private_->write_callback || 0 == decoder->private_->metadata_callback || 0 == decoder->private_->error_callback)
188 return decoder->protected_->state = FLAC__SEEKABLE_STREAM_DECODER_INVALID_CALLBACK;
190 decoder->private_->seek_table = 0;
192 decoder->private_->do_md5_checking = decoder->protected_->md5_checking;
194 /* We initialize the MD5Context even though we may never use it. This is
195 * because md5 checking may be turned on to start and then turned off if a
196 * seek occurs. So we always init the context here and finalize it in
197 * FLAC__seekable_stream_decoder_finish() to make sure things are always
198 * cleaned up properly.
200 MD5Init(&decoder->private_->md5context);
202 FLAC__stream_decoder_set_read_callback(decoder->private_->stream_decoder, read_callback_);
203 FLAC__stream_decoder_set_write_callback(decoder->private_->stream_decoder, write_callback_);
204 FLAC__stream_decoder_set_metadata_callback(decoder->private_->stream_decoder, metadata_callback_);
205 FLAC__stream_decoder_set_error_callback(decoder->private_->stream_decoder, error_callback_);
206 FLAC__stream_decoder_set_client_data(decoder->private_->stream_decoder, decoder);
208 /* We always want to see these blocks. Whether or not we pass them up
209 * through the metadata callback will be determined by flags set in our
210 * implementation of ..._set_metadata_respond/ignore...()
212 FLAC__stream_decoder_set_metadata_respond(decoder->private_->stream_decoder, FLAC__METADATA_TYPE_STREAMINFO);
213 FLAC__stream_decoder_set_metadata_respond(decoder->private_->stream_decoder, FLAC__METADATA_TYPE_SEEKTABLE);
215 if(FLAC__stream_decoder_init(decoder->private_->stream_decoder) != FLAC__STREAM_DECODER_SEARCH_FOR_METADATA)
216 return decoder->protected_->state = FLAC__SEEKABLE_STREAM_DECODER_STREAM_DECODER_ERROR;
218 return decoder->protected_->state = FLAC__SEEKABLE_STREAM_DECODER_OK;
221 FLAC__bool FLAC__seekable_stream_decoder_finish(FLAC__SeekableStreamDecoder *decoder)
223 FLAC__bool md5_failed = false;
225 FLAC__ASSERT(decoder != 0);
226 FLAC__ASSERT(decoder->private_ != 0);
227 FLAC__ASSERT(decoder->protected_ != 0);
229 if(decoder->protected_->state == FLAC__SEEKABLE_STREAM_DECODER_UNINITIALIZED)
232 FLAC__ASSERT(decoder->private_->stream_decoder != 0);
234 /* see the comment in FLAC__seekable_stream_decoder_init() as to why we
235 * always call MD5Final()
237 MD5Final(decoder->private_->computed_md5sum, &decoder->private_->md5context);
239 FLAC__stream_decoder_finish(decoder->private_->stream_decoder);
241 if(decoder->private_->do_md5_checking) {
242 if(memcmp(decoder->private_->stored_md5sum, decoder->private_->computed_md5sum, 16))
246 seekable_stream_decoder_set_defaults_(decoder);
248 decoder->protected_->state = FLAC__SEEKABLE_STREAM_DECODER_UNINITIALIZED;
253 FLAC__bool FLAC__seekable_stream_decoder_set_md5_checking(FLAC__SeekableStreamDecoder *decoder, FLAC__bool value)
255 FLAC__ASSERT(decoder != 0);
256 FLAC__ASSERT(decoder->protected_ != 0);
257 if(decoder->protected_->state != FLAC__SEEKABLE_STREAM_DECODER_UNINITIALIZED)
259 decoder->protected_->md5_checking = value;
263 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))
265 FLAC__ASSERT(decoder != 0);
266 FLAC__ASSERT(decoder->private_ != 0);
267 FLAC__ASSERT(decoder->protected_ != 0);
268 if(decoder->protected_->state != FLAC__SEEKABLE_STREAM_DECODER_UNINITIALIZED)
270 decoder->private_->read_callback = value;
274 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))
276 FLAC__ASSERT(decoder != 0);
277 FLAC__ASSERT(decoder->private_ != 0);
278 FLAC__ASSERT(decoder->protected_ != 0);
279 if(decoder->protected_->state != FLAC__SEEKABLE_STREAM_DECODER_UNINITIALIZED)
281 decoder->private_->seek_callback = value;
285 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))
287 FLAC__ASSERT(decoder != 0);
288 FLAC__ASSERT(decoder->private_ != 0);
289 FLAC__ASSERT(decoder->protected_ != 0);
290 if(decoder->protected_->state != FLAC__SEEKABLE_STREAM_DECODER_UNINITIALIZED)
292 decoder->private_->tell_callback = value;
296 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))
298 FLAC__ASSERT(decoder != 0);
299 FLAC__ASSERT(decoder->private_ != 0);
300 FLAC__ASSERT(decoder->protected_ != 0);
301 if(decoder->protected_->state != FLAC__SEEKABLE_STREAM_DECODER_UNINITIALIZED)
303 decoder->private_->length_callback = value;
307 FLAC__bool FLAC__seekable_stream_decoder_set_eof_callback(FLAC__SeekableStreamDecoder *decoder, FLAC__bool (*value)(const FLAC__SeekableStreamDecoder *decoder, void *client_data))
309 FLAC__ASSERT(decoder != 0);
310 FLAC__ASSERT(decoder->private_ != 0);
311 FLAC__ASSERT(decoder->protected_ != 0);
312 if(decoder->protected_->state != FLAC__SEEKABLE_STREAM_DECODER_UNINITIALIZED)
314 decoder->private_->eof_callback = value;
318 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))
320 FLAC__ASSERT(decoder != 0);
321 FLAC__ASSERT(decoder->private_ != 0);
322 FLAC__ASSERT(decoder->protected_ != 0);
323 if(decoder->protected_->state != FLAC__SEEKABLE_STREAM_DECODER_UNINITIALIZED)
325 decoder->private_->write_callback = value;
329 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))
331 FLAC__ASSERT(decoder != 0);
332 FLAC__ASSERT(decoder->private_ != 0);
333 FLAC__ASSERT(decoder->protected_ != 0);
334 if(decoder->protected_->state != FLAC__SEEKABLE_STREAM_DECODER_UNINITIALIZED)
336 decoder->private_->metadata_callback = value;
340 FLAC__bool FLAC__seekable_stream_decoder_set_error_callback(FLAC__SeekableStreamDecoder *decoder, void (*value)(const FLAC__SeekableStreamDecoder *decoder, FLAC__StreamDecoderErrorStatus status, void *client_data))
342 FLAC__ASSERT(decoder != 0);
343 FLAC__ASSERT(decoder->private_ != 0);
344 FLAC__ASSERT(decoder->protected_ != 0);
345 if(decoder->protected_->state != FLAC__SEEKABLE_STREAM_DECODER_UNINITIALIZED)
347 decoder->private_->error_callback = value;
351 FLAC__bool FLAC__seekable_stream_decoder_set_client_data(FLAC__SeekableStreamDecoder *decoder, void *value)
353 FLAC__ASSERT(decoder != 0);
354 FLAC__ASSERT(decoder->private_ != 0);
355 FLAC__ASSERT(decoder->protected_ != 0);
356 if(decoder->protected_->state != FLAC__SEEKABLE_STREAM_DECODER_UNINITIALIZED)
358 decoder->private_->client_data = value;
362 FLAC__bool FLAC__seekable_stream_decoder_set_metadata_respond(FLAC__SeekableStreamDecoder *decoder, FLAC__MetadataType type)
364 FLAC__ASSERT(decoder != 0);
365 FLAC__ASSERT(decoder->private_ != 0);
366 FLAC__ASSERT(decoder->protected_ != 0);
367 FLAC__ASSERT(decoder->private_->stream_decoder != 0);
368 if(decoder->protected_->state != FLAC__SEEKABLE_STREAM_DECODER_UNINITIALIZED)
370 if(type == FLAC__METADATA_TYPE_STREAMINFO)
371 decoder->private_->ignore_stream_info_block = false;
372 else if(type == FLAC__METADATA_TYPE_SEEKTABLE)
373 decoder->private_->ignore_seek_table_block = false;
374 return FLAC__stream_decoder_set_metadata_respond(decoder->private_->stream_decoder, type);
377 FLAC__bool FLAC__seekable_stream_decoder_set_metadata_respond_application(FLAC__SeekableStreamDecoder *decoder, const FLAC__byte id[4])
379 FLAC__ASSERT(decoder != 0);
380 FLAC__ASSERT(decoder->private_ != 0);
381 FLAC__ASSERT(decoder->protected_ != 0);
382 FLAC__ASSERT(decoder->private_->stream_decoder != 0);
383 if(decoder->protected_->state != FLAC__SEEKABLE_STREAM_DECODER_UNINITIALIZED)
385 return FLAC__stream_decoder_set_metadata_respond_application(decoder->private_->stream_decoder, id);
388 FLAC__bool FLAC__seekable_stream_decoder_set_metadata_respond_all(FLAC__SeekableStreamDecoder *decoder)
390 FLAC__ASSERT(decoder != 0);
391 FLAC__ASSERT(decoder->private_ != 0);
392 FLAC__ASSERT(decoder->protected_ != 0);
393 FLAC__ASSERT(decoder->private_->stream_decoder != 0);
394 if(decoder->protected_->state != FLAC__SEEKABLE_STREAM_DECODER_UNINITIALIZED)
396 decoder->private_->ignore_stream_info_block = false;
397 decoder->private_->ignore_seek_table_block = false;
398 return FLAC__stream_decoder_set_metadata_respond_all(decoder->private_->stream_decoder);
401 FLAC__bool FLAC__seekable_stream_decoder_set_metadata_ignore(FLAC__SeekableStreamDecoder *decoder, FLAC__MetadataType type)
403 FLAC__ASSERT(decoder != 0);
404 FLAC__ASSERT(decoder->private_ != 0);
405 FLAC__ASSERT(decoder->protected_ != 0);
406 FLAC__ASSERT(decoder->private_->stream_decoder != 0);
407 if(decoder->protected_->state != FLAC__SEEKABLE_STREAM_DECODER_UNINITIALIZED)
409 if(type == FLAC__METADATA_TYPE_STREAMINFO)
410 decoder->private_->ignore_stream_info_block = true;
411 else if(type == FLAC__METADATA_TYPE_SEEKTABLE)
412 decoder->private_->ignore_seek_table_block = true;
413 return FLAC__stream_decoder_set_metadata_ignore(decoder->private_->stream_decoder, type);
416 FLAC__bool FLAC__seekable_stream_decoder_set_metadata_ignore_application(FLAC__SeekableStreamDecoder *decoder, const FLAC__byte id[4])
418 FLAC__ASSERT(decoder != 0);
419 FLAC__ASSERT(decoder->private_ != 0);
420 FLAC__ASSERT(decoder->protected_ != 0);
421 FLAC__ASSERT(decoder->private_->stream_decoder != 0);
422 if(decoder->protected_->state != FLAC__SEEKABLE_STREAM_DECODER_UNINITIALIZED)
424 return FLAC__stream_decoder_set_metadata_ignore_application(decoder->private_->stream_decoder, id);
427 FLAC__bool FLAC__seekable_stream_decoder_set_metadata_ignore_all(FLAC__SeekableStreamDecoder *decoder)
429 FLAC__ASSERT(decoder != 0);
430 FLAC__ASSERT(decoder->private_ != 0);
431 FLAC__ASSERT(decoder->protected_ != 0);
432 FLAC__ASSERT(decoder->private_->stream_decoder != 0);
433 if(decoder->protected_->state != FLAC__SEEKABLE_STREAM_DECODER_UNINITIALIZED)
435 decoder->private_->ignore_stream_info_block = true;
436 decoder->private_->ignore_seek_table_block = true;
437 return FLAC__stream_decoder_set_metadata_ignore_all(decoder->private_->stream_decoder);
440 FLAC__SeekableStreamDecoderState FLAC__seekable_stream_decoder_get_state(const FLAC__SeekableStreamDecoder *decoder)
442 FLAC__ASSERT(decoder != 0);
443 FLAC__ASSERT(decoder->protected_ != 0);
444 return decoder->protected_->state;
447 FLAC__bool FLAC__seekable_stream_decoder_get_md5_checking(const FLAC__SeekableStreamDecoder *decoder)
449 FLAC__ASSERT(decoder != 0);
450 FLAC__ASSERT(decoder->protected_ != 0);
451 return decoder->protected_->md5_checking;
454 unsigned FLAC__seekable_stream_decoder_get_channels(const FLAC__SeekableStreamDecoder *decoder)
456 FLAC__ASSERT(decoder != 0);
457 FLAC__ASSERT(decoder->private_ != 0);
458 return FLAC__stream_decoder_get_channels(decoder->private_->stream_decoder);
461 FLAC__ChannelAssignment FLAC__seekable_stream_decoder_get_channel_assignment(const FLAC__SeekableStreamDecoder *decoder)
463 FLAC__ASSERT(decoder != 0);
464 FLAC__ASSERT(decoder->private_ != 0);
465 return FLAC__stream_decoder_get_channel_assignment(decoder->private_->stream_decoder);
468 unsigned FLAC__seekable_stream_decoder_get_bits_per_sample(const FLAC__SeekableStreamDecoder *decoder)
470 FLAC__ASSERT(decoder != 0);
471 FLAC__ASSERT(decoder->private_ != 0);
472 return FLAC__stream_decoder_get_bits_per_sample(decoder->private_->stream_decoder);
475 unsigned FLAC__seekable_stream_decoder_get_sample_rate(const FLAC__SeekableStreamDecoder *decoder)
477 FLAC__ASSERT(decoder != 0);
478 FLAC__ASSERT(decoder->private_ != 0);
479 return FLAC__stream_decoder_get_sample_rate(decoder->private_->stream_decoder);
482 unsigned FLAC__seekable_stream_decoder_get_blocksize(const FLAC__SeekableStreamDecoder *decoder)
484 FLAC__ASSERT(decoder != 0);
485 FLAC__ASSERT(decoder->private_ != 0);
486 return FLAC__stream_decoder_get_blocksize(decoder->private_->stream_decoder);
489 FLAC__bool FLAC__seekable_stream_decoder_flush(FLAC__SeekableStreamDecoder *decoder)
491 FLAC__ASSERT(decoder != 0);
492 FLAC__ASSERT(decoder->private_ != 0);
493 FLAC__ASSERT(decoder->protected_ != 0);
495 decoder->private_->do_md5_checking = false;
497 if(!FLAC__stream_decoder_flush(decoder->private_->stream_decoder)) {
498 decoder->protected_->state = FLAC__SEEKABLE_STREAM_DECODER_STREAM_DECODER_ERROR;
505 FLAC__bool FLAC__seekable_stream_decoder_reset(FLAC__SeekableStreamDecoder *decoder)
507 FLAC__ASSERT(decoder != 0);
508 FLAC__ASSERT(decoder->private_ != 0);
509 FLAC__ASSERT(decoder->protected_ != 0);
511 if(!FLAC__seekable_stream_decoder_flush(decoder)) {
512 decoder->protected_->state = FLAC__SEEKABLE_STREAM_DECODER_STREAM_DECODER_ERROR;
516 if(!FLAC__stream_decoder_reset(decoder->private_->stream_decoder)) {
517 decoder->protected_->state = FLAC__SEEKABLE_STREAM_DECODER_STREAM_DECODER_ERROR;
521 decoder->private_->seek_table = 0;
523 decoder->private_->do_md5_checking = decoder->protected_->md5_checking;
525 /* We initialize the MD5Context even though we may never use it. This is
526 * because md5 checking may be turned on to start and then turned off if a
527 * seek occurs. So we always init the context here and finalize it in
528 * FLAC__seekable_stream_decoder_finish() to make sure things are always
529 * cleaned up properly.
531 MD5Init(&decoder->private_->md5context);
533 decoder->protected_->state = FLAC__SEEKABLE_STREAM_DECODER_OK;
538 FLAC__bool FLAC__seekable_stream_decoder_process_whole_stream(FLAC__SeekableStreamDecoder *decoder)
541 FLAC__ASSERT(decoder != 0);
543 if(decoder->private_->stream_decoder->protected_->state == FLAC__STREAM_DECODER_END_OF_STREAM)
544 decoder->protected_->state = FLAC__SEEKABLE_STREAM_DECODER_END_OF_STREAM;
546 if(decoder->protected_->state == FLAC__SEEKABLE_STREAM_DECODER_END_OF_STREAM)
549 FLAC__ASSERT(decoder->protected_->state == FLAC__SEEKABLE_STREAM_DECODER_OK);
551 ret = FLAC__stream_decoder_process_whole_stream(decoder->private_->stream_decoder);
553 decoder->protected_->state = FLAC__SEEKABLE_STREAM_DECODER_STREAM_DECODER_ERROR;
558 FLAC__bool FLAC__seekable_stream_decoder_process_metadata(FLAC__SeekableStreamDecoder *decoder)
561 FLAC__ASSERT(decoder != 0);
563 if(decoder->private_->stream_decoder->protected_->state == FLAC__STREAM_DECODER_END_OF_STREAM)
564 decoder->protected_->state = FLAC__SEEKABLE_STREAM_DECODER_END_OF_STREAM;
566 if(decoder->protected_->state == FLAC__SEEKABLE_STREAM_DECODER_END_OF_STREAM)
569 FLAC__ASSERT(decoder->protected_->state == FLAC__SEEKABLE_STREAM_DECODER_OK);
571 ret = FLAC__stream_decoder_process_metadata(decoder->private_->stream_decoder);
573 decoder->protected_->state = FLAC__SEEKABLE_STREAM_DECODER_STREAM_DECODER_ERROR;
578 FLAC__bool FLAC__seekable_stream_decoder_process_one_frame(FLAC__SeekableStreamDecoder *decoder)
581 FLAC__ASSERT(decoder != 0);
583 if(decoder->private_->stream_decoder->protected_->state == FLAC__STREAM_DECODER_END_OF_STREAM)
584 decoder->protected_->state = FLAC__SEEKABLE_STREAM_DECODER_END_OF_STREAM;
586 if(decoder->protected_->state == FLAC__SEEKABLE_STREAM_DECODER_END_OF_STREAM)
589 FLAC__ASSERT(decoder->protected_->state == FLAC__SEEKABLE_STREAM_DECODER_OK);
591 ret = FLAC__stream_decoder_process_one_frame(decoder->private_->stream_decoder);
593 decoder->protected_->state = FLAC__SEEKABLE_STREAM_DECODER_STREAM_DECODER_ERROR;
598 FLAC__bool FLAC__seekable_stream_decoder_process_remaining_frames(FLAC__SeekableStreamDecoder *decoder)
601 FLAC__ASSERT(decoder != 0);
603 if(decoder->private_->stream_decoder->protected_->state == FLAC__STREAM_DECODER_END_OF_STREAM)
604 decoder->protected_->state = FLAC__SEEKABLE_STREAM_DECODER_END_OF_STREAM;
606 if(decoder->protected_->state == FLAC__SEEKABLE_STREAM_DECODER_END_OF_STREAM)
609 FLAC__ASSERT(decoder->protected_->state == FLAC__SEEKABLE_STREAM_DECODER_OK);
611 ret = FLAC__stream_decoder_process_remaining_frames(decoder->private_->stream_decoder);
613 decoder->protected_->state = FLAC__SEEKABLE_STREAM_DECODER_STREAM_DECODER_ERROR;
618 FLAC__bool FLAC__seekable_stream_decoder_seek_absolute(FLAC__SeekableStreamDecoder *decoder, FLAC__uint64 sample)
622 FLAC__ASSERT(decoder != 0);
623 FLAC__ASSERT(decoder->protected_->state == FLAC__SEEKABLE_STREAM_DECODER_OK || decoder->protected_->state == FLAC__SEEKABLE_STREAM_DECODER_END_OF_STREAM);
625 decoder->protected_->state = FLAC__SEEKABLE_STREAM_DECODER_SEEKING;
627 /* turn off md5 checking if a seek is attempted */
628 decoder->private_->do_md5_checking = false;
630 if(!FLAC__stream_decoder_reset(decoder->private_->stream_decoder)) {
631 decoder->protected_->state = FLAC__SEEKABLE_STREAM_DECODER_STREAM_DECODER_ERROR;
634 /* get the file length */
635 if(decoder->private_->length_callback(decoder, &length, decoder->private_->client_data) != FLAC__SEEKABLE_STREAM_DECODER_LENGTH_STATUS_OK) {
636 decoder->protected_->state = FLAC__SEEKABLE_STREAM_DECODER_SEEK_ERROR;
640 if(decoder->private_->seek_callback(decoder, 0, decoder->private_->client_data) != FLAC__SEEKABLE_STREAM_DECODER_SEEK_STATUS_OK) {
641 decoder->protected_->state = FLAC__SEEKABLE_STREAM_DECODER_SEEK_ERROR;
644 if(!FLAC__stream_decoder_process_metadata(decoder->private_->stream_decoder)) {
645 decoder->protected_->state = FLAC__SEEKABLE_STREAM_DECODER_STREAM_DECODER_ERROR;
648 if(decoder->private_->stream_info.total_samples > 0 && sample > decoder->private_->stream_info.total_samples) {
649 decoder->protected_->state = FLAC__SEEKABLE_STREAM_DECODER_SEEK_ERROR;
653 return seek_to_absolute_sample_(decoder, length, sample);
656 /***********************************************************************
658 * Private class methods
660 ***********************************************************************/
662 void seekable_stream_decoder_set_defaults_(FLAC__SeekableStreamDecoder *decoder)
664 decoder->private_->read_callback = 0;
665 decoder->private_->seek_callback = 0;
666 decoder->private_->tell_callback = 0;
667 decoder->private_->length_callback = 0;
668 decoder->private_->eof_callback = 0;
669 decoder->private_->write_callback = 0;
670 decoder->private_->metadata_callback = 0;
671 decoder->private_->error_callback = 0;
672 decoder->private_->client_data = 0;
673 /* WATCHOUT: these should match the default behavior of FLAC__StreamDecoder */
674 decoder->private_->ignore_stream_info_block = false;
675 decoder->private_->ignore_seek_table_block = true;
677 decoder->protected_->md5_checking = false;
680 FLAC__StreamDecoderReadStatus read_callback_(const FLAC__StreamDecoder *decoder, FLAC__byte buffer[], unsigned *bytes, void *client_data)
682 FLAC__SeekableStreamDecoder *seekable_stream_decoder = (FLAC__SeekableStreamDecoder *)client_data;
684 if(seekable_stream_decoder->private_->eof_callback(seekable_stream_decoder, seekable_stream_decoder->private_->client_data)) {
685 seekable_stream_decoder->protected_->state = FLAC__SEEKABLE_STREAM_DECODER_END_OF_STREAM;
686 return FLAC__STREAM_DECODER_READ_STATUS_END_OF_STREAM;
688 else if(*bytes > 0) {
689 unsigned bytes_read = *bytes;
690 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) {
691 seekable_stream_decoder->protected_->state = FLAC__SEEKABLE_STREAM_DECODER_READ_ERROR;
692 return FLAC__STREAM_DECODER_READ_STATUS_ABORT;
694 if(bytes_read == 0) {
695 if(seekable_stream_decoder->private_->eof_callback(seekable_stream_decoder, seekable_stream_decoder->private_->client_data)) {
696 seekable_stream_decoder->protected_->state = FLAC__SEEKABLE_STREAM_DECODER_END_OF_STREAM;
697 return FLAC__STREAM_DECODER_READ_STATUS_END_OF_STREAM;
700 return FLAC__STREAM_DECODER_READ_STATUS_CONTINUE;
704 return FLAC__STREAM_DECODER_READ_STATUS_CONTINUE;
708 return FLAC__STREAM_DECODER_READ_STATUS_ABORT; /* abort to avoid a deadlock */
711 FLAC__StreamDecoderWriteStatus write_callback_(const FLAC__StreamDecoder *decoder, const FLAC__Frame *frame, const FLAC__int32 * const buffer[], void *client_data)
713 FLAC__SeekableStreamDecoder *seekable_stream_decoder = (FLAC__SeekableStreamDecoder *)client_data;
716 if(seekable_stream_decoder->protected_->state == FLAC__SEEKABLE_STREAM_DECODER_SEEKING) {
717 FLAC__uint64 this_frame_sample = frame->header.number.sample_number;
718 FLAC__uint64 next_frame_sample = this_frame_sample + (FLAC__uint64)frame->header.blocksize;
719 FLAC__uint64 target_sample = seekable_stream_decoder->private_->target_sample;
721 FLAC__ASSERT(frame->header.number_type == FLAC__FRAME_NUMBER_TYPE_SAMPLE_NUMBER);
723 seekable_stream_decoder->private_->last_frame = *frame; /* save the frame */
724 if(this_frame_sample <= target_sample && target_sample < next_frame_sample) { /* we hit our target frame */
725 unsigned delta = (unsigned)(target_sample - this_frame_sample);
726 /* kick out of seek mode */
727 seekable_stream_decoder->protected_->state = FLAC__SEEKABLE_STREAM_DECODER_OK;
728 /* shift out the samples before target_sample */
731 const FLAC__int32 *newbuffer[FLAC__MAX_CHANNELS];
732 for(channel = 0; channel < frame->header.channels; channel++)
733 newbuffer[channel] = buffer[channel] + delta;
734 seekable_stream_decoder->private_->last_frame.header.blocksize -= delta;
735 seekable_stream_decoder->private_->last_frame.header.number.sample_number += (FLAC__uint64)delta;
736 /* write the relevant samples */
737 return seekable_stream_decoder->private_->write_callback(seekable_stream_decoder, &seekable_stream_decoder->private_->last_frame, newbuffer, seekable_stream_decoder->private_->client_data);
740 /* write the relevant samples */
741 return seekable_stream_decoder->private_->write_callback(seekable_stream_decoder, frame, buffer, seekable_stream_decoder->private_->client_data);
745 return FLAC__STREAM_DECODER_WRITE_STATUS_CONTINUE;
749 if(seekable_stream_decoder->private_->do_md5_checking) {
750 if(!FLAC__MD5Accumulate(&seekable_stream_decoder->private_->md5context, buffer, frame->header.channels, frame->header.blocksize, (frame->header.bits_per_sample+7) / 8))
751 return FLAC__STREAM_DECODER_WRITE_STATUS_ABORT;
753 return seekable_stream_decoder->private_->write_callback(seekable_stream_decoder, frame, buffer, seekable_stream_decoder->private_->client_data);
757 void metadata_callback_(const FLAC__StreamDecoder *decoder, const FLAC__StreamMetadata *metadata, void *client_data)
759 FLAC__SeekableStreamDecoder *seekable_stream_decoder = (FLAC__SeekableStreamDecoder *)client_data;
762 if(metadata->type == FLAC__METADATA_TYPE_STREAMINFO) {
763 seekable_stream_decoder->private_->stream_info = metadata->data.stream_info;
764 /* save the MD5 signature for comparison later */
765 memcpy(seekable_stream_decoder->private_->stored_md5sum, metadata->data.stream_info.md5sum, 16);
766 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))
767 seekable_stream_decoder->private_->do_md5_checking = false;
769 else if(metadata->type == FLAC__METADATA_TYPE_SEEKTABLE) {
770 seekable_stream_decoder->private_->seek_table = &metadata->data.seek_table;
773 if(seekable_stream_decoder->protected_->state != FLAC__SEEKABLE_STREAM_DECODER_SEEKING) {
774 FLAC__bool ignore_block = false;
775 if(metadata->type == FLAC__METADATA_TYPE_STREAMINFO && seekable_stream_decoder->private_->ignore_stream_info_block)
777 else if(metadata->type == FLAC__METADATA_TYPE_SEEKTABLE && seekable_stream_decoder->private_->ignore_seek_table_block)
780 seekable_stream_decoder->private_->metadata_callback(seekable_stream_decoder, metadata, seekable_stream_decoder->private_->client_data);
784 void error_callback_(const FLAC__StreamDecoder *decoder, FLAC__StreamDecoderErrorStatus status, void *client_data)
786 FLAC__SeekableStreamDecoder *seekable_stream_decoder = (FLAC__SeekableStreamDecoder *)client_data;
789 if(seekable_stream_decoder->protected_->state != FLAC__SEEKABLE_STREAM_DECODER_SEEKING)
790 seekable_stream_decoder->private_->error_callback(seekable_stream_decoder, status, seekable_stream_decoder->private_->client_data);
793 FLAC__bool seek_to_absolute_sample_(FLAC__SeekableStreamDecoder *decoder, FLAC__uint64 stream_length, FLAC__uint64 target_sample)
795 FLAC__uint64 first_frame_offset, lower_bound, upper_bound;
796 FLAC__int64 pos = -1, last_pos = -1;
797 int i, lower_seek_point = -1, upper_seek_point = -1;
798 unsigned approx_bytes_per_frame;
799 FLAC__uint64 last_frame_sample = 0xffffffffffffffff;
800 FLAC__bool needs_seek;
801 const FLAC__uint64 total_samples = decoder->private_->stream_info.total_samples;
802 const unsigned min_blocksize = decoder->private_->stream_info.min_blocksize;
803 const unsigned max_blocksize = decoder->private_->stream_info.max_blocksize;
804 const unsigned max_framesize = decoder->private_->stream_info.max_framesize;
805 const unsigned channels = FLAC__seekable_stream_decoder_get_channels(decoder);
806 const unsigned bps = FLAC__seekable_stream_decoder_get_bits_per_sample(decoder);
808 /* we are just guessing here, but we want to guess high, not low */
809 if(max_framesize > 0) {
810 approx_bytes_per_frame = max_framesize;
813 * Check if it's a known fixed-blocksize stream. Note that though
814 * the spec doesn't allow zeroes in the STREAMINFO block, we may
815 * never get a STREAMINFO block when decoding so the value of
816 * min_blocksize might be zero.
818 else if(min_blocksize == max_blocksize && min_blocksize > 0) {
819 /* note there are no () around 'bps/8' to keep precision up since it's an integer calulation */
820 approx_bytes_per_frame = min_blocksize * channels * bps/8 + 64;
823 approx_bytes_per_frame = 4608 * channels * bps/8 + 64;
826 * The stream position is currently at the first frame plus any read
827 * ahead data, so first we get the stream position, then subtract
828 * uncomsumed bytes to get the position of the first frame in the
831 if(decoder->private_->tell_callback(decoder, &first_frame_offset, decoder->private_->client_data) != FLAC__SEEKABLE_STREAM_DECODER_TELL_STATUS_OK) {
832 decoder->protected_->state = FLAC__SEEKABLE_STREAM_DECODER_SEEK_ERROR;
835 FLAC__ASSERT(first_frame_offset >= FLAC__stream_decoder_get_input_bytes_unconsumed(decoder->private_->stream_decoder));
836 first_frame_offset -= FLAC__stream_decoder_get_input_bytes_unconsumed(decoder->private_->stream_decoder);
839 * First, we set an upper and lower bound on where in the
840 * stream we will search. For now we assume the worst case
841 * scenario, which is our best guess at the beginning of
842 * the first and last frames.
844 lower_bound = first_frame_offset;
846 /* calc the upper_bound, beyond which we never want to seek */
847 if(max_framesize > 0)
848 upper_bound = stream_length - (max_framesize + 128 + 2); /* 128 for a possible ID3V1 tag, 2 for indexing differences */
850 upper_bound = stream_length - ((channels * bps * FLAC__MAX_BLOCK_SIZE) / 8 + 128 + 2);
853 * Now we refine the bounds if we have a seektable with
854 * suitable points. Note that according to the spec they
855 * must be ordered by ascending sample number.
857 if(0 != decoder->private_->seek_table) {
858 /* find the closest seek point <= target_sample, if it exists */
859 for(i = (int)decoder->private_->seek_table->num_points - 1; i >= 0; i--) {
860 if(decoder->private_->seek_table->points[i].sample_number != FLAC__STREAM_METADATA_SEEKPOINT_PLACEHOLDER && decoder->private_->seek_table->points[i].sample_number <= target_sample)
863 if(i >= 0) { /* i.e. we found a suitable seek point... */
864 lower_bound = first_frame_offset + decoder->private_->seek_table->points[i].stream_offset;
865 lower_seek_point = i;
868 /* find the closest seek point > target_sample, if it exists */
869 for(i = 0; i < (int)decoder->private_->seek_table->num_points; i++) {
870 if(decoder->private_->seek_table->points[i].sample_number != FLAC__STREAM_METADATA_SEEKPOINT_PLACEHOLDER && decoder->private_->seek_table->points[i].sample_number > target_sample)
873 if(i < (int)decoder->private_->seek_table->num_points) { /* i.e. we found a suitable seek point... */
874 upper_bound = first_frame_offset + decoder->private_->seek_table->points[i].stream_offset;
875 upper_seek_point = i;
880 * Now guess at where within those bounds our target
883 if(lower_seek_point >= 0) {
884 /* first see if our sample is within a few frames of the lower seekpoint */
885 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)) {
886 pos = (FLAC__int64)lower_bound;
888 else if(upper_seek_point >= 0) {
889 const FLAC__uint64 target_offset = target_sample - decoder->private_->seek_table->points[lower_seek_point].sample_number;
890 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;
891 const FLAC__uint64 range_bytes = upper_bound - lower_bound;
892 #if defined _MSC_VER || defined __MINGW32__
893 /* with VC++ you have to spoon feed it the casting */
894 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;
896 pos = (FLAC__int64)lower_bound + (FLAC__int64)((double)target_offset / (double)range_samples * (double)(range_bytes-1)) - approx_bytes_per_frame;
902 * If there's no seek table, we need to use the metadata (if we
903 * have it) and the filelength to estimate the position of the
904 * frame with the correct sample.
906 if(pos < 0 && total_samples > 0) {
907 #if defined _MSC_VER || defined __MINGW32__
908 /* with VC++ you have to spoon feed it the casting */
909 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;
911 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;
916 * If there's no seek table and total_samples is unknown, we
917 * don't even bother trying to figure out a target, we just use
918 * our current position.
922 if(decoder->private_->tell_callback(decoder, &upos, decoder->private_->client_data) != FLAC__SEEKABLE_STREAM_DECODER_TELL_STATUS_OK) {
923 decoder->protected_->state = FLAC__SEEKABLE_STREAM_DECODER_SEEK_ERROR;
926 pos = (FLAC__int32)upos;
932 /* clip the position to the bounds, lower bound takes precedence */
933 if(pos >= (FLAC__int64)upper_bound) {
934 pos = (FLAC__int64)upper_bound-1;
937 if(pos < (FLAC__int64)lower_bound) {
938 pos = (FLAC__int64)lower_bound;
942 decoder->private_->target_sample = target_sample;
945 if(decoder->private_->seek_callback(decoder, (FLAC__uint64)pos, decoder->private_->client_data) != FLAC__SEEKABLE_STREAM_DECODER_SEEK_STATUS_OK) {
946 decoder->protected_->state = FLAC__SEEKABLE_STREAM_DECODER_SEEK_ERROR;
949 if(!FLAC__stream_decoder_flush(decoder->private_->stream_decoder)) {
950 decoder->protected_->state = FLAC__SEEKABLE_STREAM_DECODER_STREAM_DECODER_ERROR;
954 if(!FLAC__stream_decoder_process_one_frame(decoder->private_->stream_decoder)) {
955 decoder->protected_->state = FLAC__SEEKABLE_STREAM_DECODER_SEEK_ERROR;
958 /* our write callback will change the state when it gets to the target frame */
959 if(decoder->protected_->state != FLAC__SEEKABLE_STREAM_DECODER_SEEKING) {
962 else { /* we need to narrow the search */
963 FLAC__uint64 this_frame_sample = decoder->private_->last_frame.header.number.sample_number;
964 FLAC__ASSERT(decoder->private_->last_frame.header.number_type == FLAC__FRAME_NUMBER_TYPE_SAMPLE_NUMBER);
965 if(this_frame_sample == last_frame_sample) {
966 /* our last move backwards wasn't big enough */
967 pos -= (last_pos - pos);
971 if(target_sample < this_frame_sample) {
973 approx_bytes_per_frame = decoder->private_->last_frame.header.blocksize * channels * bps/8 + 64;
974 pos -= approx_bytes_per_frame;
977 else { /* target_sample >= this_frame_sample + this frame's blocksize */
979 if(decoder->private_->tell_callback(decoder, &upos, decoder->private_->client_data) != FLAC__SEEKABLE_STREAM_DECODER_TELL_STATUS_OK) {
980 decoder->protected_->state = FLAC__SEEKABLE_STREAM_DECODER_SEEK_ERROR;
984 pos = (FLAC__int32)upos;
985 pos -= FLAC__stream_decoder_get_input_bytes_unconsumed(decoder->private_->stream_decoder);
989 if(pos < (FLAC__int64)lower_bound)
990 pos = (FLAC__int64)lower_bound;
991 last_frame_sample = this_frame_sample;