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1 /* libFLAC - Free Lossless Audio Codec library
2  * Copyright (C) 2000-2009  Josh Coalson
3  * Copyright (C) 2011-2022  Xiph.Org Foundation
4  *
5  * Redistribution and use in source and binary forms, with or without
6  * modification, are permitted provided that the following conditions
7  * are met:
8  *
9  * - Redistributions of source code must retain the above copyright
10  * notice, this list of conditions and the following disclaimer.
11  *
12  * - Redistributions in binary form must reproduce the above copyright
13  * notice, this list of conditions and the following disclaimer in the
14  * documentation and/or other materials provided with the distribution.
15  *
16  * - Neither the name of the Xiph.org Foundation nor the names of its
17  * contributors may be used to endorse or promote products derived from
18  * this software without specific prior written permission.
19  *
20  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
21  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
22  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
23  * A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR
24  * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
25  * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
26  * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
27  * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
28  * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
29  * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
30  * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
31  */
32 
33 #ifndef FLAC__FORMAT_H
34 #define FLAC__FORMAT_H
35 
36 #include "export.h"
37 #include "ordinals.h"
38 
39 #ifdef __cplusplus
40 extern "C" {
41 #endif
42 
43 /** \file include/FLAC/format.h
44  *
45  *  \brief
46  *  This module contains structure definitions for the representation
47  *  of FLAC format components in memory.  These are the basic
48  *  structures used by the rest of the interfaces.
49  *
50  *  See the detailed documentation in the
51  *  \link flac_format format \endlink module.
52  */
53 
54 /** \defgroup flac_format FLAC/format.h: format components
55  *  \ingroup flac
56  *
57  *  \brief
58  *  This module contains structure definitions for the representation
59  *  of FLAC format components in memory.  These are the basic
60  *  structures used by the rest of the interfaces.
61  *
62  *  First, you should be familiar with the
63  *  <A HREF="https://xiph.org/flac/format.html">FLAC format</A>.  Many of the values here
64  *  follow directly from the specification.  As a user of libFLAC, the
65  *  interesting parts really are the structures that describe the frame
66  *  header and metadata blocks.
67  *
68  *  The format structures here are very primitive, designed to store
69  *  information in an efficient way.  Reading information from the
70  *  structures is easy but creating or modifying them directly is
71  *  more complex.  For the most part, as a user of a library, editing
72  *  is not necessary; however, for metadata blocks it is, so there are
73  *  convenience functions provided in the \link flac_metadata metadata
74  *  module \endlink to simplify the manipulation of metadata blocks.
75  *
76  * \note
77  * It's not the best convention, but symbols ending in _LEN are in bits
78  * and _LENGTH are in bytes.  _LENGTH symbols are \#defines instead of
79  * global variables because they are usually used when declaring byte
80  * arrays and some compilers require compile-time knowledge of array
81  * sizes when declared on the stack.
82  *
83  * \{
84  */
85 
86 
87 /*
88 	Most of the values described in this file are defined by the FLAC
89 	format specification.  There is nothing to tune here.
90 */
91 
92 /** The largest legal metadata type code. */
93 #define FLAC__MAX_METADATA_TYPE_CODE (126u)
94 
95 /** The minimum block size, in samples, permitted by the format. */
96 #define FLAC__MIN_BLOCK_SIZE (16u)
97 
98 /** The maximum block size, in samples, permitted by the format. */
99 #define FLAC__MAX_BLOCK_SIZE (65535u)
100 
101 /** The maximum block size, in samples, permitted by the FLAC subset for
102  *  sample rates up to 48kHz. */
103 #define FLAC__SUBSET_MAX_BLOCK_SIZE_48000HZ (4608u)
104 
105 /** The maximum number of channels permitted by the format. */
106 #define FLAC__MAX_CHANNELS (8u)
107 
108 /** The minimum sample resolution permitted by the format. */
109 #define FLAC__MIN_BITS_PER_SAMPLE (4u)
110 
111 /** The maximum sample resolution permitted by the format. */
112 #define FLAC__MAX_BITS_PER_SAMPLE (32u)
113 
114 /** The maximum sample resolution permitted by libFLAC.
115  *
116  * FLAC__MAX_BITS_PER_SAMPLE is the limit of the FLAC format.  However,
117  * the reference encoder/decoder used to be limited to 24 bits. This
118  * value was used to signal that limit.
119  */
120 #define FLAC__REFERENCE_CODEC_MAX_BITS_PER_SAMPLE (32u)
121 
122 /** The maximum sample rate permitted by the format.  The value is
123  *  ((2 ^ 20) - 1)
124  */
125 #define FLAC__MAX_SAMPLE_RATE (1048575u)
126 
127 /** The maximum LPC order permitted by the format. */
128 #define FLAC__MAX_LPC_ORDER (32u)
129 
130 /** The maximum LPC order permitted by the FLAC subset for sample rates
131  *  up to 48kHz. */
132 #define FLAC__SUBSET_MAX_LPC_ORDER_48000HZ (12u)
133 
134 /** The minimum quantized linear predictor coefficient precision
135  *  permitted by the format.
136  */
137 #define FLAC__MIN_QLP_COEFF_PRECISION (5u)
138 
139 /** The maximum quantized linear predictor coefficient precision
140  *  permitted by the format.
141  */
142 #define FLAC__MAX_QLP_COEFF_PRECISION (15u)
143 
144 /** The maximum order of the fixed predictors permitted by the format. */
145 #define FLAC__MAX_FIXED_ORDER (4u)
146 
147 /** The maximum Rice partition order permitted by the format. */
148 #define FLAC__MAX_RICE_PARTITION_ORDER (15u)
149 
150 /** The maximum Rice partition order permitted by the FLAC Subset. */
151 #define FLAC__SUBSET_MAX_RICE_PARTITION_ORDER (8u)
152 
153 /** The version string of the release, stamped onto the libraries and binaries.
154  *
155  * \note
156  * This does not correspond to the shared library version number, which
157  * is used to determine binary compatibility.
158  */
159 extern FLAC_API const char *FLAC__VERSION_STRING;
160 
161 /** The vendor string inserted by the encoder into the VORBIS_COMMENT block.
162  *  This is a NUL-terminated ASCII string; when inserted into the
163  *  VORBIS_COMMENT the trailing null is stripped.
164  */
165 extern FLAC_API const char *FLAC__VENDOR_STRING;
166 
167 /** The byte string representation of the beginning of a FLAC stream. */
168 extern FLAC_API const FLAC__byte FLAC__STREAM_SYNC_STRING[4]; /* = "fLaC" */
169 
170 /** The 32-bit integer big-endian representation of the beginning of
171  *  a FLAC stream.
172  */
173 extern FLAC_API const uint32_t FLAC__STREAM_SYNC; /* = 0x664C6143 */
174 
175 /** The length of the FLAC signature in bits. */
176 extern FLAC_API const uint32_t FLAC__STREAM_SYNC_LEN; /* = 32 bits */
177 
178 /** The length of the FLAC signature in bytes. */
179 #define FLAC__STREAM_SYNC_LENGTH (4u)
180 
181 
182 /*****************************************************************************
183  *
184  * Subframe structures
185  *
186  *****************************************************************************/
187 
188 /*****************************************************************************/
189 
190 /** An enumeration of the available entropy coding methods. */
191 typedef enum {
192 	FLAC__ENTROPY_CODING_METHOD_PARTITIONED_RICE = 0,
193 	/**< Residual is coded by partitioning into contexts, each with it's own
194 	 * 4-bit Rice parameter. */
195 
196 	FLAC__ENTROPY_CODING_METHOD_PARTITIONED_RICE2 = 1
197 	/**< Residual is coded by partitioning into contexts, each with it's own
198 	 * 5-bit Rice parameter. */
199 } FLAC__EntropyCodingMethodType;
200 
201 /** Maps a FLAC__EntropyCodingMethodType to a C string.
202  *
203  *  Using a FLAC__EntropyCodingMethodType as the index to this array will
204  *  give the string equivalent.  The contents should not be modified.
205  */
206 extern FLAC_API const char * const FLAC__EntropyCodingMethodTypeString[];
207 
208 
209 /** Contents of a Rice partitioned residual
210  */
211 typedef struct {
212 
213 	uint32_t *parameters;
214 	/**< The Rice parameters for each context. */
215 
216 	uint32_t *raw_bits;
217 	/**< Widths for escape-coded partitions.  Will be non-zero for escaped
218 	 * partitions and zero for unescaped partitions.
219 	 */
220 
221 	uint32_t capacity_by_order;
222 	/**< The capacity of the \a parameters and \a raw_bits arrays
223 	 * specified as an order, i.e. the number of array elements
224 	 * allocated is 2 ^ \a capacity_by_order.
225 	 */
226 } FLAC__EntropyCodingMethod_PartitionedRiceContents;
227 
228 /** Header for a Rice partitioned residual.  (c.f. <A HREF="https://xiph.org/flac/format.html#partitioned_rice">format specification</A>)
229  */
230 typedef struct {
231 
232 	uint32_t order;
233 	/**< The partition order, i.e. # of contexts = 2 ^ \a order. */
234 
235 	const FLAC__EntropyCodingMethod_PartitionedRiceContents *contents;
236 	/**< The context's Rice parameters and/or raw bits. */
237 
238 } FLAC__EntropyCodingMethod_PartitionedRice;
239 
240 extern FLAC_API const uint32_t FLAC__ENTROPY_CODING_METHOD_PARTITIONED_RICE_ORDER_LEN; /**< == 4 (bits) */
241 extern FLAC_API const uint32_t FLAC__ENTROPY_CODING_METHOD_PARTITIONED_RICE_PARAMETER_LEN; /**< == 4 (bits) */
242 extern FLAC_API const uint32_t FLAC__ENTROPY_CODING_METHOD_PARTITIONED_RICE2_PARAMETER_LEN; /**< == 5 (bits) */
243 extern FLAC_API const uint32_t FLAC__ENTROPY_CODING_METHOD_PARTITIONED_RICE_RAW_LEN; /**< == 5 (bits) */
244 
245 extern FLAC_API const uint32_t FLAC__ENTROPY_CODING_METHOD_PARTITIONED_RICE_ESCAPE_PARAMETER;
246 /**< == (1<<FLAC__ENTROPY_CODING_METHOD_PARTITIONED_RICE_PARAMETER_LEN)-1 */
247 extern FLAC_API const uint32_t FLAC__ENTROPY_CODING_METHOD_PARTITIONED_RICE2_ESCAPE_PARAMETER;
248 /**< == (1<<FLAC__ENTROPY_CODING_METHOD_PARTITIONED_RICE2_PARAMETER_LEN)-1 */
249 
250 /** Header for the entropy coding method.  (c.f. <A HREF="https://xiph.org/flac/format.html#residual">format specification</A>)
251  */
252 typedef struct {
253 	FLAC__EntropyCodingMethodType type;
254 	union {
255 		FLAC__EntropyCodingMethod_PartitionedRice partitioned_rice;
256 	} data;
257 } FLAC__EntropyCodingMethod;
258 
259 extern FLAC_API const uint32_t FLAC__ENTROPY_CODING_METHOD_TYPE_LEN; /**< == 2 (bits) */
260 
261 /*****************************************************************************/
262 
263 /** An enumeration of the available subframe types. */
264 typedef enum {
265 	FLAC__SUBFRAME_TYPE_CONSTANT = 0, /**< constant signal */
266 	FLAC__SUBFRAME_TYPE_VERBATIM = 1, /**< uncompressed signal */
267 	FLAC__SUBFRAME_TYPE_FIXED = 2, /**< fixed polynomial prediction */
268 	FLAC__SUBFRAME_TYPE_LPC = 3 /**< linear prediction */
269 } FLAC__SubframeType;
270 
271 /** Maps a FLAC__SubframeType to a C string.
272  *
273  *  Using a FLAC__SubframeType as the index to this array will
274  *  give the string equivalent.  The contents should not be modified.
275  */
276 extern FLAC_API const char * const FLAC__SubframeTypeString[];
277 
278 
279 /** CONSTANT subframe.  (c.f. <A HREF="https://xiph.org/flac/format.html#subframe_constant">format specification</A>)
280  */
281 typedef struct {
282 	FLAC__int64 value; /**< The constant signal value. */
283 } FLAC__Subframe_Constant;
284 
285 /** An enumeration of the possible verbatim subframe data types. */
286 typedef enum {
287 	FLAC__VERBATIM_SUBFRAME_DATA_TYPE_INT32, /**< verbatim subframe has 32-bit int */
288 	FLAC__VERBATIM_SUBFRAME_DATA_TYPE_INT64 /**< verbatim subframe has 64-bit int */
289 } FLAC__VerbatimSubframeDataType;
290 
291 
292 /** VERBATIM subframe.  (c.f. <A HREF="https://xiph.org/flac/format.html#subframe_verbatim">format specification</A>)
293  */
294 typedef struct {
295 	union {
296 		const FLAC__int32 *int32; /**< A FLAC__int32 pointer to verbatim signal. */
297 		const FLAC__int64 *int64; /**< A FLAC__int64 pointer to verbatim signal. */
298 	} data;
299 	FLAC__VerbatimSubframeDataType data_type;
300 } FLAC__Subframe_Verbatim;
301 
302 
303 /** FIXED subframe.  (c.f. <A HREF="https://xiph.org/flac/format.html#subframe_fixed">format specification</A>)
304  */
305 typedef struct {
306 	FLAC__EntropyCodingMethod entropy_coding_method;
307 	/**< The residual coding method. */
308 
309 	uint32_t order;
310 	/**< The polynomial order. */
311 
312 	FLAC__int64 warmup[FLAC__MAX_FIXED_ORDER];
313 	/**< Warmup samples to prime the predictor, length == order. */
314 
315 	const FLAC__int32 *residual;
316 	/**< The residual signal, length == (blocksize minus order) samples. */
317 } FLAC__Subframe_Fixed;
318 
319 
320 /** LPC subframe.  (c.f. <A HREF="https://xiph.org/flac/format.html#subframe_lpc">format specification</A>)
321  */
322 typedef struct {
323 	FLAC__EntropyCodingMethod entropy_coding_method;
324 	/**< The residual coding method. */
325 
326 	uint32_t order;
327 	/**< The FIR order. */
328 
329 	uint32_t qlp_coeff_precision;
330 	/**< Quantized FIR filter coefficient precision in bits. */
331 
332 	int quantization_level;
333 	/**< The qlp coeff shift needed. */
334 
335 	FLAC__int32 qlp_coeff[FLAC__MAX_LPC_ORDER];
336 	/**< FIR filter coefficients. */
337 
338 	FLAC__int64 warmup[FLAC__MAX_LPC_ORDER];
339 	/**< Warmup samples to prime the predictor, length == order. */
340 
341 	const FLAC__int32 *residual;
342 	/**< The residual signal, length == (blocksize minus order) samples. */
343 } FLAC__Subframe_LPC;
344 
345 extern FLAC_API const uint32_t FLAC__SUBFRAME_LPC_QLP_COEFF_PRECISION_LEN; /**< == 4 (bits) */
346 extern FLAC_API const uint32_t FLAC__SUBFRAME_LPC_QLP_SHIFT_LEN; /**< == 5 (bits) */
347 
348 
349 /** FLAC subframe structure.  (c.f. <A HREF="https://xiph.org/flac/format.html#subframe">format specification</A>)
350  */
351 typedef struct {
352 	FLAC__SubframeType type;
353 	union {
354 		FLAC__Subframe_Constant constant;
355 		FLAC__Subframe_Fixed fixed;
356 		FLAC__Subframe_LPC lpc;
357 		FLAC__Subframe_Verbatim verbatim;
358 	} data;
359 	uint32_t wasted_bits;
360 } FLAC__Subframe;
361 
362 /** == 1 (bit)
363  *
364  * This used to be a zero-padding bit (hence the name
365  * FLAC__SUBFRAME_ZERO_PAD_LEN) but is now a reserved bit.  It still has a
366  * mandatory value of \c 0 but in the future may take on the value \c 0 or \c 1
367  * to mean something else.
368  */
369 extern FLAC_API const uint32_t FLAC__SUBFRAME_ZERO_PAD_LEN;
370 extern FLAC_API const uint32_t FLAC__SUBFRAME_TYPE_LEN; /**< == 6 (bits) */
371 extern FLAC_API const uint32_t FLAC__SUBFRAME_WASTED_BITS_FLAG_LEN; /**< == 1 (bit) */
372 
373 extern FLAC_API const uint32_t FLAC__SUBFRAME_TYPE_CONSTANT_BYTE_ALIGNED_MASK; /**< = 0x00 */
374 extern FLAC_API const uint32_t FLAC__SUBFRAME_TYPE_VERBATIM_BYTE_ALIGNED_MASK; /**< = 0x02 */
375 extern FLAC_API const uint32_t FLAC__SUBFRAME_TYPE_FIXED_BYTE_ALIGNED_MASK; /**< = 0x10 */
376 extern FLAC_API const uint32_t FLAC__SUBFRAME_TYPE_LPC_BYTE_ALIGNED_MASK; /**< = 0x40 */
377 
378 /*****************************************************************************/
379 
380 
381 /*****************************************************************************
382  *
383  * Frame structures
384  *
385  *****************************************************************************/
386 
387 /** An enumeration of the available channel assignments. */
388 typedef enum {
389 	FLAC__CHANNEL_ASSIGNMENT_INDEPENDENT = 0, /**< independent channels */
390 	FLAC__CHANNEL_ASSIGNMENT_LEFT_SIDE = 1, /**< left+side stereo */
391 	FLAC__CHANNEL_ASSIGNMENT_RIGHT_SIDE = 2, /**< right+side stereo */
392 	FLAC__CHANNEL_ASSIGNMENT_MID_SIDE = 3 /**< mid+side stereo */
393 } FLAC__ChannelAssignment;
394 
395 /** Maps a FLAC__ChannelAssignment to a C string.
396  *
397  *  Using a FLAC__ChannelAssignment as the index to this array will
398  *  give the string equivalent.  The contents should not be modified.
399  */
400 extern FLAC_API const char * const FLAC__ChannelAssignmentString[];
401 
402 /** An enumeration of the possible frame numbering methods. */
403 typedef enum {
404 	FLAC__FRAME_NUMBER_TYPE_FRAME_NUMBER, /**< number contains the frame number */
405 	FLAC__FRAME_NUMBER_TYPE_SAMPLE_NUMBER /**< number contains the sample number of first sample in frame */
406 } FLAC__FrameNumberType;
407 
408 /** Maps a FLAC__FrameNumberType to a C string.
409  *
410  *  Using a FLAC__FrameNumberType as the index to this array will
411  *  give the string equivalent.  The contents should not be modified.
412  */
413 extern FLAC_API const char * const FLAC__FrameNumberTypeString[];
414 
415 
416 /** FLAC frame header structure.  (c.f. <A HREF="https://xiph.org/flac/format.html#frame_header">format specification</A>)
417  */
418 typedef struct {
419 	uint32_t blocksize;
420 	/**< The number of samples per subframe. */
421 
422 	uint32_t sample_rate;
423 	/**< The sample rate in Hz. */
424 
425 	uint32_t channels;
426 	/**< The number of channels (== number of subframes). */
427 
428 	FLAC__ChannelAssignment channel_assignment;
429 	/**< The channel assignment for the frame. */
430 
431 	uint32_t bits_per_sample;
432 	/**< The sample resolution. */
433 
434 	FLAC__FrameNumberType number_type;
435 	/**< The numbering scheme used for the frame.  As a convenience, the
436 	 * decoder will always convert a frame number to a sample number because
437 	 * the rules are complex. */
438 
439 	union {
440 		FLAC__uint32 frame_number;
441 		FLAC__uint64 sample_number;
442 	} number;
443 	/**< The frame number or sample number of first sample in frame;
444 	 * use the \a number_type value to determine which to use. */
445 
446 	FLAC__uint8 crc;
447 	/**< CRC-8 (polynomial = x^8 + x^2 + x^1 + x^0, initialized with 0)
448 	 * of the raw frame header bytes, meaning everything before the CRC byte
449 	 * including the sync code.
450 	 */
451 } FLAC__FrameHeader;
452 
453 extern FLAC_API const uint32_t FLAC__FRAME_HEADER_SYNC; /**< == 0x3ffe; the frame header sync code */
454 extern FLAC_API const uint32_t FLAC__FRAME_HEADER_SYNC_LEN; /**< == 14 (bits) */
455 extern FLAC_API const uint32_t FLAC__FRAME_HEADER_RESERVED_LEN; /**< == 1 (bits) */
456 extern FLAC_API const uint32_t FLAC__FRAME_HEADER_BLOCKING_STRATEGY_LEN; /**< == 1 (bits) */
457 extern FLAC_API const uint32_t FLAC__FRAME_HEADER_BLOCK_SIZE_LEN; /**< == 4 (bits) */
458 extern FLAC_API const uint32_t FLAC__FRAME_HEADER_SAMPLE_RATE_LEN; /**< == 4 (bits) */
459 extern FLAC_API const uint32_t FLAC__FRAME_HEADER_CHANNEL_ASSIGNMENT_LEN; /**< == 4 (bits) */
460 extern FLAC_API const uint32_t FLAC__FRAME_HEADER_BITS_PER_SAMPLE_LEN; /**< == 3 (bits) */
461 extern FLAC_API const uint32_t FLAC__FRAME_HEADER_ZERO_PAD_LEN; /**< == 1 (bit) */
462 extern FLAC_API const uint32_t FLAC__FRAME_HEADER_CRC_LEN; /**< == 8 (bits) */
463 
464 
465 /** FLAC frame footer structure.  (c.f. <A HREF="https://xiph.org/flac/format.html#frame_footer">format specification</A>)
466  */
467 typedef struct {
468 	FLAC__uint16 crc;
469 	/**< CRC-16 (polynomial = x^16 + x^15 + x^2 + x^0, initialized with
470 	 * 0) of the bytes before the crc, back to and including the frame header
471 	 * sync code.
472 	 */
473 } FLAC__FrameFooter;
474 
475 extern FLAC_API const uint32_t FLAC__FRAME_FOOTER_CRC_LEN; /**< == 16 (bits) */
476 
477 
478 /** FLAC frame structure.  (c.f. <A HREF="https://xiph.org/flac/format.html#frame">format specification</A>)
479  */
480 typedef struct {
481 	FLAC__FrameHeader header;
482 	FLAC__Subframe subframes[FLAC__MAX_CHANNELS];
483 	FLAC__FrameFooter footer;
484 } FLAC__Frame;
485 
486 /*****************************************************************************/
487 
488 
489 /*****************************************************************************
490  *
491  * Meta-data structures
492  *
493  *****************************************************************************/
494 
495 /** An enumeration of the available metadata block types. */
496 typedef enum {
497 
498 	FLAC__METADATA_TYPE_STREAMINFO = 0,
499 	/**< <A HREF="https://xiph.org/flac/format.html#metadata_block_streaminfo">STREAMINFO</A> block */
500 
501 	FLAC__METADATA_TYPE_PADDING = 1,
502 	/**< <A HREF="https://xiph.org/flac/format.html#metadata_block_padding">PADDING</A> block */
503 
504 	FLAC__METADATA_TYPE_APPLICATION = 2,
505 	/**< <A HREF="https://xiph.org/flac/format.html#metadata_block_application">APPLICATION</A> block */
506 
507 	FLAC__METADATA_TYPE_SEEKTABLE = 3,
508 	/**< <A HREF="https://xiph.org/flac/format.html#metadata_block_seektable">SEEKTABLE</A> block */
509 
510 	FLAC__METADATA_TYPE_VORBIS_COMMENT = 4,
511 	/**< <A HREF="https://xiph.org/flac/format.html#metadata_block_vorbis_comment">VORBISCOMMENT</A> block (a.k.a. FLAC tags) */
512 
513 	FLAC__METADATA_TYPE_CUESHEET = 5,
514 	/**< <A HREF="https://xiph.org/flac/format.html#metadata_block_cuesheet">CUESHEET</A> block */
515 
516 	FLAC__METADATA_TYPE_PICTURE = 6,
517 	/**< <A HREF="https://xiph.org/flac/format.html#metadata_block_picture">PICTURE</A> block */
518 
519 	FLAC__METADATA_TYPE_UNDEFINED = 7,
520 	/**< marker to denote beginning of undefined type range; this number will increase as new metadata types are added */
521 
522 	FLAC__MAX_METADATA_TYPE = FLAC__MAX_METADATA_TYPE_CODE,
523 	/**< No type will ever be greater than this. There is not enough room in the protocol block. */
524 } FLAC__MetadataType;
525 
526 /** Maps a FLAC__MetadataType to a C string.
527  *
528  *  Using a FLAC__MetadataType as the index to this array will
529  *  give the string equivalent.  The contents should not be modified.
530  */
531 extern FLAC_API const char * const FLAC__MetadataTypeString[];
532 
533 
534 /** FLAC STREAMINFO structure.  (c.f. <A HREF="https://xiph.org/flac/format.html#metadata_block_streaminfo">format specification</A>)
535  */
536 typedef struct {
537 	uint32_t min_blocksize, max_blocksize;
538 	uint32_t min_framesize, max_framesize;
539 	uint32_t sample_rate;
540 	uint32_t channels;
541 	uint32_t bits_per_sample;
542 	FLAC__uint64 total_samples;
543 	FLAC__byte md5sum[16];
544 } FLAC__StreamMetadata_StreamInfo;
545 
546 extern FLAC_API const uint32_t FLAC__STREAM_METADATA_STREAMINFO_MIN_BLOCK_SIZE_LEN; /**< == 16 (bits) */
547 extern FLAC_API const uint32_t FLAC__STREAM_METADATA_STREAMINFO_MAX_BLOCK_SIZE_LEN; /**< == 16 (bits) */
548 extern FLAC_API const uint32_t FLAC__STREAM_METADATA_STREAMINFO_MIN_FRAME_SIZE_LEN; /**< == 24 (bits) */
549 extern FLAC_API const uint32_t FLAC__STREAM_METADATA_STREAMINFO_MAX_FRAME_SIZE_LEN; /**< == 24 (bits) */
550 extern FLAC_API const uint32_t FLAC__STREAM_METADATA_STREAMINFO_SAMPLE_RATE_LEN; /**< == 20 (bits) */
551 extern FLAC_API const uint32_t FLAC__STREAM_METADATA_STREAMINFO_CHANNELS_LEN; /**< == 3 (bits) */
552 extern FLAC_API const uint32_t FLAC__STREAM_METADATA_STREAMINFO_BITS_PER_SAMPLE_LEN; /**< == 5 (bits) */
553 extern FLAC_API const uint32_t FLAC__STREAM_METADATA_STREAMINFO_TOTAL_SAMPLES_LEN; /**< == 36 (bits) */
554 extern FLAC_API const uint32_t FLAC__STREAM_METADATA_STREAMINFO_MD5SUM_LEN; /**< == 128 (bits) */
555 
556 /** The total stream length of the STREAMINFO block in bytes. */
557 #define FLAC__STREAM_METADATA_STREAMINFO_LENGTH (34u)
558 
559 /** FLAC PADDING structure.  (c.f. <A HREF="https://xiph.org/flac/format.html#metadata_block_padding">format specification</A>)
560  */
561 typedef struct {
562 	int dummy;
563 	/**< Conceptually this is an empty struct since we don't store the
564 	 * padding bytes.  Empty structs are not allowed by some C compilers,
565 	 * hence the dummy.
566 	 */
567 } FLAC__StreamMetadata_Padding;
568 
569 
570 /** FLAC APPLICATION structure.  (c.f. <A HREF="https://xiph.org/flac/format.html#metadata_block_application">format specification</A>)
571  */
572 typedef struct {
573 	FLAC__byte id[4];
574 	FLAC__byte *data;
575 } FLAC__StreamMetadata_Application;
576 
577 extern FLAC_API const uint32_t FLAC__STREAM_METADATA_APPLICATION_ID_LEN; /**< == 32 (bits) */
578 
579 /** SeekPoint structure used in SEEKTABLE blocks.  (c.f. <A HREF="https://xiph.org/flac/format.html#seekpoint">format specification</A>)
580  */
581 typedef struct {
582 	FLAC__uint64 sample_number;
583 	/**<  The sample number of the target frame. */
584 
585 	FLAC__uint64 stream_offset;
586 	/**< The offset, in bytes, of the target frame with respect to
587 	 * beginning of the first frame. */
588 
589 	uint32_t frame_samples;
590 	/**< The number of samples in the target frame. */
591 } FLAC__StreamMetadata_SeekPoint;
592 
593 extern FLAC_API const uint32_t FLAC__STREAM_METADATA_SEEKPOINT_SAMPLE_NUMBER_LEN; /**< == 64 (bits) */
594 extern FLAC_API const uint32_t FLAC__STREAM_METADATA_SEEKPOINT_STREAM_OFFSET_LEN; /**< == 64 (bits) */
595 extern FLAC_API const uint32_t FLAC__STREAM_METADATA_SEEKPOINT_FRAME_SAMPLES_LEN; /**< == 16 (bits) */
596 
597 /** The total stream length of a seek point in bytes. */
598 #define FLAC__STREAM_METADATA_SEEKPOINT_LENGTH (18u)
599 
600 /** The value used in the \a sample_number field of
601  *  FLAC__StreamMetadataSeekPoint used to indicate a placeholder
602  *  point (== 0xffffffffffffffff).
603  */
604 extern FLAC_API const FLAC__uint64 FLAC__STREAM_METADATA_SEEKPOINT_PLACEHOLDER;
605 
606 
607 /** FLAC SEEKTABLE structure.  (c.f. <A HREF="https://xiph.org/flac/format.html#metadata_block_seektable">format specification</A>)
608  *
609  * \note From the format specification:
610  * - The seek points must be sorted by ascending sample number.
611  * - Each seek point's sample number must be the first sample of the
612  *   target frame.
613  * - Each seek point's sample number must be unique within the table.
614  * - Existence of a SEEKTABLE block implies a correct setting of
615  *   total_samples in the stream_info block.
616  * - Behavior is undefined when more than one SEEKTABLE block is
617  *   present in a stream.
618  */
619 typedef struct {
620 	uint32_t num_points;
621 	FLAC__StreamMetadata_SeekPoint *points;
622 } FLAC__StreamMetadata_SeekTable;
623 
624 
625 /** Vorbis comment entry structure used in VORBIS_COMMENT blocks.  (c.f. <A HREF="https://xiph.org/flac/format.html#metadata_block_vorbis_comment">format specification</A>)
626  *
627  *  For convenience, the APIs maintain a trailing NUL character at the end of
628  *  \a entry which is not counted toward \a length, i.e.
629  *  \code strlen(entry) == length \endcode
630  */
631 typedef struct {
632 	FLAC__uint32 length;
633 	FLAC__byte *entry;
634 } FLAC__StreamMetadata_VorbisComment_Entry;
635 
636 extern FLAC_API const uint32_t FLAC__STREAM_METADATA_VORBIS_COMMENT_ENTRY_LENGTH_LEN; /**< == 32 (bits) */
637 
638 
639 /** FLAC VORBIS_COMMENT structure.  (c.f. <A HREF="https://xiph.org/flac/format.html#metadata_block_vorbis_comment">format specification</A>)
640  */
641 typedef struct {
642 	FLAC__StreamMetadata_VorbisComment_Entry vendor_string;
643 	FLAC__uint32 num_comments;
644 	FLAC__StreamMetadata_VorbisComment_Entry *comments;
645 } FLAC__StreamMetadata_VorbisComment;
646 
647 extern FLAC_API const uint32_t FLAC__STREAM_METADATA_VORBIS_COMMENT_NUM_COMMENTS_LEN; /**< == 32 (bits) */
648 
649 
650 /** FLAC CUESHEET track index structure.  (See the
651  * <A HREF="https://xiph.org/flac/format.html#cuesheet_track_index">format specification</A> for
652  * the full description of each field.)
653  */
654 typedef struct {
655 	FLAC__uint64 offset;
656 	/**< Offset in samples, relative to the track offset, of the index
657 	 * point.
658 	 */
659 
660 	FLAC__byte number;
661 	/**< The index point number. */
662 } FLAC__StreamMetadata_CueSheet_Index;
663 
664 extern FLAC_API const uint32_t FLAC__STREAM_METADATA_CUESHEET_INDEX_OFFSET_LEN; /**< == 64 (bits) */
665 extern FLAC_API const uint32_t FLAC__STREAM_METADATA_CUESHEET_INDEX_NUMBER_LEN; /**< == 8 (bits) */
666 extern FLAC_API const uint32_t FLAC__STREAM_METADATA_CUESHEET_INDEX_RESERVED_LEN; /**< == 3*8 (bits) */
667 
668 
669 /** FLAC CUESHEET track structure.  (See the
670  * <A HREF="https://xiph.org/flac/format.html#cuesheet_track">format specification</A> for
671  * the full description of each field.)
672  */
673 typedef struct {
674 	FLAC__uint64 offset;
675 	/**< Track offset in samples, relative to the beginning of the FLAC audio stream. */
676 
677 	FLAC__byte number;
678 	/**< The track number. */
679 
680 	char isrc[13];
681 	/**< Track ISRC.  This is a 12-digit alphanumeric code plus a trailing \c NUL byte */
682 
683 	uint32_t type:1;
684 	/**< The track type: 0 for audio, 1 for non-audio. */
685 
686 	uint32_t pre_emphasis:1;
687 	/**< The pre-emphasis flag: 0 for no pre-emphasis, 1 for pre-emphasis. */
688 
689 	FLAC__byte num_indices;
690 	/**< The number of track index points. */
691 
692 	FLAC__StreamMetadata_CueSheet_Index *indices;
693 	/**< NULL if num_indices == 0, else pointer to array of index points. */
694 
695 } FLAC__StreamMetadata_CueSheet_Track;
696 
697 extern FLAC_API const uint32_t FLAC__STREAM_METADATA_CUESHEET_TRACK_OFFSET_LEN; /**< == 64 (bits) */
698 extern FLAC_API const uint32_t FLAC__STREAM_METADATA_CUESHEET_TRACK_NUMBER_LEN; /**< == 8 (bits) */
699 extern FLAC_API const uint32_t FLAC__STREAM_METADATA_CUESHEET_TRACK_ISRC_LEN; /**< == 12*8 (bits) */
700 extern FLAC_API const uint32_t FLAC__STREAM_METADATA_CUESHEET_TRACK_TYPE_LEN; /**< == 1 (bit) */
701 extern FLAC_API const uint32_t FLAC__STREAM_METADATA_CUESHEET_TRACK_PRE_EMPHASIS_LEN; /**< == 1 (bit) */
702 extern FLAC_API const uint32_t FLAC__STREAM_METADATA_CUESHEET_TRACK_RESERVED_LEN; /**< == 6+13*8 (bits) */
703 extern FLAC_API const uint32_t FLAC__STREAM_METADATA_CUESHEET_TRACK_NUM_INDICES_LEN; /**< == 8 (bits) */
704 
705 
706 /** FLAC CUESHEET structure.  (See the
707  * <A HREF="https://xiph.org/flac/format.html#metadata_block_cuesheet">format specification</A>
708  * for the full description of each field.)
709  */
710 typedef struct {
711 	char media_catalog_number[129];
712 	/**< Media catalog number, in ASCII printable characters 0x20-0x7e.  In
713 	 * general, the media catalog number may be 0 to 128 bytes long; any
714 	 * unused characters should be right-padded with NUL characters.
715 	 */
716 
717 	FLAC__uint64 lead_in;
718 	/**< The number of lead-in samples. */
719 
720 	FLAC__bool is_cd;
721 	/**< \c true if CUESHEET corresponds to a Compact Disc, else \c false. */
722 
723 	uint32_t num_tracks;
724 	/**< The number of tracks. */
725 
726 	FLAC__StreamMetadata_CueSheet_Track *tracks;
727 	/**< NULL if num_tracks == 0, else pointer to array of tracks. */
728 
729 } FLAC__StreamMetadata_CueSheet;
730 
731 extern FLAC_API const uint32_t FLAC__STREAM_METADATA_CUESHEET_MEDIA_CATALOG_NUMBER_LEN; /**< == 128*8 (bits) */
732 extern FLAC_API const uint32_t FLAC__STREAM_METADATA_CUESHEET_LEAD_IN_LEN; /**< == 64 (bits) */
733 extern FLAC_API const uint32_t FLAC__STREAM_METADATA_CUESHEET_IS_CD_LEN; /**< == 1 (bit) */
734 extern FLAC_API const uint32_t FLAC__STREAM_METADATA_CUESHEET_RESERVED_LEN; /**< == 7+258*8 (bits) */
735 extern FLAC_API const uint32_t FLAC__STREAM_METADATA_CUESHEET_NUM_TRACKS_LEN; /**< == 8 (bits) */
736 
737 
738 /** An enumeration of the PICTURE types (see FLAC__StreamMetadataPicture and id3 v2.4 APIC tag). */
739 typedef enum {
740 	FLAC__STREAM_METADATA_PICTURE_TYPE_OTHER = 0, /**< Other */
741 	FLAC__STREAM_METADATA_PICTURE_TYPE_FILE_ICON_STANDARD = 1, /**< 32x32 pixels 'file icon' (PNG only) */
742 	FLAC__STREAM_METADATA_PICTURE_TYPE_FILE_ICON = 2, /**< Other file icon */
743 	FLAC__STREAM_METADATA_PICTURE_TYPE_FRONT_COVER = 3, /**< Cover (front) */
744 	FLAC__STREAM_METADATA_PICTURE_TYPE_BACK_COVER = 4, /**< Cover (back) */
745 	FLAC__STREAM_METADATA_PICTURE_TYPE_LEAFLET_PAGE = 5, /**< Leaflet page */
746 	FLAC__STREAM_METADATA_PICTURE_TYPE_MEDIA = 6, /**< Media (e.g. label side of CD) */
747 	FLAC__STREAM_METADATA_PICTURE_TYPE_LEAD_ARTIST = 7, /**< Lead artist/lead performer/soloist */
748 	FLAC__STREAM_METADATA_PICTURE_TYPE_ARTIST = 8, /**< Artist/performer */
749 	FLAC__STREAM_METADATA_PICTURE_TYPE_CONDUCTOR = 9, /**< Conductor */
750 	FLAC__STREAM_METADATA_PICTURE_TYPE_BAND = 10, /**< Band/Orchestra */
751 	FLAC__STREAM_METADATA_PICTURE_TYPE_COMPOSER = 11, /**< Composer */
752 	FLAC__STREAM_METADATA_PICTURE_TYPE_LYRICIST = 12, /**< Lyricist/text writer */
753 	FLAC__STREAM_METADATA_PICTURE_TYPE_RECORDING_LOCATION = 13, /**< Recording Location */
754 	FLAC__STREAM_METADATA_PICTURE_TYPE_DURING_RECORDING = 14, /**< During recording */
755 	FLAC__STREAM_METADATA_PICTURE_TYPE_DURING_PERFORMANCE = 15, /**< During performance */
756 	FLAC__STREAM_METADATA_PICTURE_TYPE_VIDEO_SCREEN_CAPTURE = 16, /**< Movie/video screen capture */
757 	FLAC__STREAM_METADATA_PICTURE_TYPE_FISH = 17, /**< A bright coloured fish */
758 	FLAC__STREAM_METADATA_PICTURE_TYPE_ILLUSTRATION = 18, /**< Illustration */
759 	FLAC__STREAM_METADATA_PICTURE_TYPE_BAND_LOGOTYPE = 19, /**< Band/artist logotype */
760 	FLAC__STREAM_METADATA_PICTURE_TYPE_PUBLISHER_LOGOTYPE = 20, /**< Publisher/Studio logotype */
761 	FLAC__STREAM_METADATA_PICTURE_TYPE_UNDEFINED
762 } FLAC__StreamMetadata_Picture_Type;
763 
764 /** Maps a FLAC__StreamMetadata_Picture_Type to a C string.
765  *
766  *  Using a FLAC__StreamMetadata_Picture_Type as the index to this array
767  *  will give the string equivalent.  The contents should not be
768  *  modified.
769  */
770 extern FLAC_API const char * const FLAC__StreamMetadata_Picture_TypeString[];
771 
772 /** FLAC PICTURE structure.  (See the
773  * <A HREF="https://xiph.org/flac/format.html#metadata_block_picture">format specification</A>
774  * for the full description of each field.)
775  */
776 typedef struct {
777 	FLAC__StreamMetadata_Picture_Type type;
778 	/**< The kind of picture stored. */
779 
780 	char *mime_type;
781 	/**< Picture data's MIME type, in ASCII printable characters
782 	 * 0x20-0x7e, NUL terminated.  For best compatibility with players,
783 	 * use picture data of MIME type \c image/jpeg or \c image/png.  A
784 	 * MIME type of '-->' is also allowed, in which case the picture
785 	 * data should be a complete URL.  In file storage, the MIME type is
786 	 * stored as a 32-bit length followed by the ASCII string with no NUL
787 	 * terminator, but is converted to a plain C string in this structure
788 	 * for convenience.
789 	 */
790 
791 	FLAC__byte *description;
792 	/**< Picture's description in UTF-8, NUL terminated.  In file storage,
793 	 * the description is stored as a 32-bit length followed by the UTF-8
794 	 * string with no NUL terminator, but is converted to a plain C string
795 	 * in this structure for convenience.
796 	 */
797 
798 	FLAC__uint32 width;
799 	/**< Picture's width in pixels. */
800 
801 	FLAC__uint32 height;
802 	/**< Picture's height in pixels. */
803 
804 	FLAC__uint32 depth;
805 	/**< Picture's color depth in bits-per-pixel. */
806 
807 	FLAC__uint32 colors;
808 	/**< For indexed palettes (like GIF), picture's number of colors (the
809 	 * number of palette entries), or \c 0 for non-indexed (i.e. 2^depth).
810 	 */
811 
812 	FLAC__uint32 data_length;
813 	/**< Length of binary picture data in bytes. */
814 
815 	FLAC__byte *data;
816 	/**< Binary picture data. */
817 
818 } FLAC__StreamMetadata_Picture;
819 
820 extern FLAC_API const uint32_t FLAC__STREAM_METADATA_PICTURE_TYPE_LEN; /**< == 32 (bits) */
821 extern FLAC_API const uint32_t FLAC__STREAM_METADATA_PICTURE_MIME_TYPE_LENGTH_LEN; /**< == 32 (bits) */
822 extern FLAC_API const uint32_t FLAC__STREAM_METADATA_PICTURE_DESCRIPTION_LENGTH_LEN; /**< == 32 (bits) */
823 extern FLAC_API const uint32_t FLAC__STREAM_METADATA_PICTURE_WIDTH_LEN; /**< == 32 (bits) */
824 extern FLAC_API const uint32_t FLAC__STREAM_METADATA_PICTURE_HEIGHT_LEN; /**< == 32 (bits) */
825 extern FLAC_API const uint32_t FLAC__STREAM_METADATA_PICTURE_DEPTH_LEN; /**< == 32 (bits) */
826 extern FLAC_API const uint32_t FLAC__STREAM_METADATA_PICTURE_COLORS_LEN; /**< == 32 (bits) */
827 extern FLAC_API const uint32_t FLAC__STREAM_METADATA_PICTURE_DATA_LENGTH_LEN; /**< == 32 (bits) */
828 
829 
830 /** Structure that is used when a metadata block of unknown type is loaded.
831  *  The contents are opaque.  The structure is used only internally to
832  *  correctly handle unknown metadata.
833  */
834 typedef struct {
835 	FLAC__byte *data;
836 } FLAC__StreamMetadata_Unknown;
837 
838 
839 /** FLAC metadata block structure.  (c.f. <A HREF="https://xiph.org/flac/format.html#metadata_block">format specification</A>)
840  */
841 typedef struct FLAC__StreamMetadata {
842 	FLAC__MetadataType type;
843 	/**< The type of the metadata block; used determine which member of the
844 	 * \a data union to dereference.  If type >= FLAC__METADATA_TYPE_UNDEFINED
845 	 * then \a data.unknown must be used. */
846 
847 	FLAC__bool is_last;
848 	/**< \c true if this metadata block is the last, else \a false */
849 
850 	uint32_t length;
851 	/**< Length, in bytes, of the block data as it appears in the stream. */
852 
853 	union {
854 		FLAC__StreamMetadata_StreamInfo stream_info;
855 		FLAC__StreamMetadata_Padding padding;
856 		FLAC__StreamMetadata_Application application;
857 		FLAC__StreamMetadata_SeekTable seek_table;
858 		FLAC__StreamMetadata_VorbisComment vorbis_comment;
859 		FLAC__StreamMetadata_CueSheet cue_sheet;
860 		FLAC__StreamMetadata_Picture picture;
861 		FLAC__StreamMetadata_Unknown unknown;
862 	} data;
863 	/**< Polymorphic block data; use the \a type value to determine which
864 	 * to use. */
865 } FLAC__StreamMetadata;
866 
867 extern FLAC_API const uint32_t FLAC__STREAM_METADATA_IS_LAST_LEN; /**< == 1 (bit) */
868 extern FLAC_API const uint32_t FLAC__STREAM_METADATA_TYPE_LEN; /**< == 7 (bits) */
869 extern FLAC_API const uint32_t FLAC__STREAM_METADATA_LENGTH_LEN; /**< == 24 (bits) */
870 
871 /** The total stream length of a metadata block header in bytes. */
872 #define FLAC__STREAM_METADATA_HEADER_LENGTH (4u)
873 
874 /*****************************************************************************/
875 
876 
877 /*****************************************************************************
878  *
879  * Utility functions
880  *
881  *****************************************************************************/
882 
883 /** Tests that a sample rate is valid for FLAC.
884  *
885  * \param sample_rate  The sample rate to test for compliance.
886  * \retval FLAC__bool
887  *    \c true if the given sample rate conforms to the specification, else
888  *    \c false.
889  */
890 FLAC_API FLAC__bool FLAC__format_sample_rate_is_valid(uint32_t sample_rate);
891 
892 /** Tests that a blocksize at the given sample rate is valid for the FLAC
893  *  subset.
894  *
895  * \param blocksize    The blocksize to test for compliance.
896  * \param sample_rate  The sample rate is needed, since the valid subset
897  *                     blocksize depends on the sample rate.
898  * \retval FLAC__bool
899  *    \c true if the given blocksize conforms to the specification for the
900  *    subset at the given sample rate, else \c false.
901  */
902 FLAC_API FLAC__bool FLAC__format_blocksize_is_subset(uint32_t blocksize, uint32_t sample_rate);
903 
904 /** Tests that a sample rate is valid for the FLAC subset.  The subset rules
905  *  for valid sample rates are slightly more complex since the rate has to
906  *  be expressible completely in the frame header.
907  *
908  * \param sample_rate  The sample rate to test for compliance.
909  * \retval FLAC__bool
910  *    \c true if the given sample rate conforms to the specification for the
911  *    subset, else \c false.
912  */
913 FLAC_API FLAC__bool FLAC__format_sample_rate_is_subset(uint32_t sample_rate);
914 
915 /** Check a Vorbis comment entry name to see if it conforms to the Vorbis
916  *  comment specification.
917  *
918  *  Vorbis comment names must be composed only of characters from
919  *  [0x20-0x3C,0x3E-0x7D].
920  *
921  * \param name       A NUL-terminated string to be checked.
922  * \assert
923  *    \code name != NULL \endcode
924  * \retval FLAC__bool
925  *    \c false if entry name is illegal, else \c true.
926  */
927 FLAC_API FLAC__bool FLAC__format_vorbiscomment_entry_name_is_legal(const char *name);
928 
929 /** Check a Vorbis comment entry value to see if it conforms to the Vorbis
930  *  comment specification.
931  *
932  *  Vorbis comment values must be valid UTF-8 sequences.
933  *
934  * \param value      A string to be checked.
935  * \param length     A the length of \a value in bytes.  May be
936  *                   \c (uint32_t)(-1) to indicate that \a value is a plain
937  *                   UTF-8 NUL-terminated string.
938  * \assert
939  *    \code value != NULL \endcode
940  * \retval FLAC__bool
941  *    \c false if entry name is illegal, else \c true.
942  */
943 FLAC_API FLAC__bool FLAC__format_vorbiscomment_entry_value_is_legal(const FLAC__byte *value, uint32_t length);
944 
945 /** Check a Vorbis comment entry to see if it conforms to the Vorbis
946  *  comment specification.
947  *
948  *  Vorbis comment entries must be of the form 'name=value', and 'name' and
949  *  'value' must be legal according to
950  *  FLAC__format_vorbiscomment_entry_name_is_legal() and
951  *  FLAC__format_vorbiscomment_entry_value_is_legal() respectively.
952  *
953  * \param entry      An entry to be checked.
954  * \param length     The length of \a entry in bytes.
955  * \assert
956  *    \code value != NULL \endcode
957  * \retval FLAC__bool
958  *    \c false if entry name is illegal, else \c true.
959  */
960 FLAC_API FLAC__bool FLAC__format_vorbiscomment_entry_is_legal(const FLAC__byte *entry, uint32_t length);
961 
962 /** Check a seek table to see if it conforms to the FLAC specification.
963  *  See the format specification for limits on the contents of the
964  *  seek table.
965  *
966  * \param seek_table  A pointer to a seek table to be checked.
967  * \assert
968  *    \code seek_table != NULL \endcode
969  * \retval FLAC__bool
970  *    \c false if seek table is illegal, else \c true.
971  */
972 FLAC_API FLAC__bool FLAC__format_seektable_is_legal(const FLAC__StreamMetadata_SeekTable *seek_table);
973 
974 /** Sort a seek table's seek points according to the format specification.
975  *  This includes a "unique-ification" step to remove duplicates, i.e.
976  *  seek points with identical \a sample_number values.  Duplicate seek
977  *  points are converted into placeholder points and sorted to the end of
978  *  the table.
979  *
980  * \param seek_table  A pointer to a seek table to be sorted.
981  * \assert
982  *    \code seek_table != NULL \endcode
983  * \retval uint32_t
984  *    The number of duplicate seek points converted into placeholders.
985  */
986 FLAC_API uint32_t FLAC__format_seektable_sort(FLAC__StreamMetadata_SeekTable *seek_table);
987 
988 /** Check a cue sheet to see if it conforms to the FLAC specification.
989  *  See the format specification for limits on the contents of the
990  *  cue sheet.
991  *
992  * \param cue_sheet  A pointer to an existing cue sheet to be checked.
993  * \param check_cd_da_subset  If \c true, check CUESHEET against more
994  *                   stringent requirements for a CD-DA (audio) disc.
995  * \param violation  Address of a pointer to a string.  If there is a
996  *                   violation, a pointer to a string explanation of the
997  *                   violation will be returned here. \a violation may be
998  *                   \c NULL if you don't need the returned string.  Do not
999  *                   free the returned string; it will always point to static
1000  *                   data.
1001  * \assert
1002  *    \code cue_sheet != NULL \endcode
1003  * \retval FLAC__bool
1004  *    \c false if cue sheet is illegal, else \c true.
1005  */
1006 FLAC_API FLAC__bool FLAC__format_cuesheet_is_legal(const FLAC__StreamMetadata_CueSheet *cue_sheet, FLAC__bool check_cd_da_subset, const char **violation);
1007 
1008 /** Check picture data to see if it conforms to the FLAC specification.
1009  *  See the format specification for limits on the contents of the
1010  *  PICTURE block.
1011  *
1012  * \param picture    A pointer to existing picture data to be checked.
1013  * \param violation  Address of a pointer to a string.  If there is a
1014  *                   violation, a pointer to a string explanation of the
1015  *                   violation will be returned here. \a violation may be
1016  *                   \c NULL if you don't need the returned string.  Do not
1017  *                   free the returned string; it will always point to static
1018  *                   data.
1019  * \assert
1020  *    \code picture != NULL \endcode
1021  * \retval FLAC__bool
1022  *    \c false if picture data is illegal, else \c true.
1023  */
1024 FLAC_API FLAC__bool FLAC__format_picture_is_legal(const FLAC__StreamMetadata_Picture *picture, const char **violation);
1025 
1026 /* \} */
1027 
1028 #ifdef __cplusplus
1029 }
1030 #endif
1031 
1032 #endif
1033