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opt.h
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1 /*
2  * AVOptions
3  * copyright (c) 2005 Michael Niedermayer <michaelni@gmx.at>
4  *
5  * This file is part of FFmpeg.
6  *
7  * FFmpeg is free software; you can redistribute it and/or
8  * modify it under the terms of the GNU Lesser General Public
9  * License as published by the Free Software Foundation; either
10  * version 2.1 of the License, or (at your option) any later version.
11  *
12  * FFmpeg is distributed in the hope that it will be useful,
13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15  * Lesser General Public License for more details.
16  *
17  * You should have received a copy of the GNU Lesser General Public
18  * License along with FFmpeg; if not, write to the Free Software
19  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
20  */
21 
22 #ifndef AVUTIL_OPT_H
23 #define AVUTIL_OPT_H
24 
25 /**
26  * @file
27  * AVOptions
28  */
29 
30 #include "rational.h"
31 #include "avutil.h"
32 #include "dict.h"
33 #include "log.h"
34 #include "pixfmt.h"
35 #include "samplefmt.h"
36 #include "version.h"
37 
38 /**
39  * @defgroup avoptions AVOptions
40  * @ingroup lavu_data
41  * @{
42  * AVOptions provide a generic system to declare options on arbitrary structs
43  * ("objects"). An option can have a help text, a type and a range of possible
44  * values. Options may then be enumerated, read and written to.
45  *
46  * @section avoptions_implement Implementing AVOptions
47  * This section describes how to add AVOptions capabilities to a struct.
48  *
49  * All AVOptions-related information is stored in an AVClass. Therefore
50  * the first member of the struct should be a pointer to an AVClass describing it.
51  * The option field of the AVClass must be set to a NULL-terminated static array
52  * of AVOptions. Each AVOption must have a non-empty name, a type, a default
53  * value and for number-type AVOptions also a range of allowed values. It must
54  * also declare an offset in bytes from the start of the struct, where the field
55  * associated with this AVOption is located. Other fields in the AVOption struct
56  * should also be set when applicable, but are not required.
57  *
58  * The following example illustrates an AVOptions-enabled struct:
59  * @code
60  * typedef struct test_struct {
61  * const AVClass *class;
62  * int int_opt;
63  * char *str_opt;
64  * uint8_t *bin_opt;
65  * int bin_len;
66  * } test_struct;
67  *
68  * static const AVOption test_options[] = {
69  * { "test_int", "This is a test option of int type.", offsetof(test_struct, int_opt),
70  * AV_OPT_TYPE_INT, { .i64 = -1 }, INT_MIN, INT_MAX },
71  * { "test_str", "This is a test option of string type.", offsetof(test_struct, str_opt),
72  * AV_OPT_TYPE_STRING },
73  * { "test_bin", "This is a test option of binary type.", offsetof(test_struct, bin_opt),
74  * AV_OPT_TYPE_BINARY },
75  * { NULL },
76  * };
77  *
78  * static const AVClass test_class = {
79  * .class_name = "test class",
80  * .item_name = av_default_item_name,
81  * .option = test_options,
82  * .version = LIBAVUTIL_VERSION_INT,
83  * };
84  * @endcode
85  *
86  * Next, when allocating your struct, you must ensure that the AVClass pointer
87  * is set to the correct value. Then, av_opt_set_defaults() can be called to
88  * initialize defaults. After that the struct is ready to be used with the
89  * AVOptions API.
90  *
91  * When cleaning up, you may use the av_opt_free() function to automatically
92  * free all the allocated string and binary options.
93  *
94  * Continuing with the above example:
95  *
96  * @code
97  * test_struct *alloc_test_struct(void)
98  * {
99  * test_struct *ret = av_mallocz(sizeof(*ret));
100  * ret->class = &test_class;
101  * av_opt_set_defaults(ret);
102  * return ret;
103  * }
104  * void free_test_struct(test_struct **foo)
105  * {
106  * av_opt_free(*foo);
107  * av_freep(foo);
108  * }
109  * @endcode
110  *
111  * @subsection avoptions_implement_nesting Nesting
112  * It may happen that an AVOptions-enabled struct contains another
113  * AVOptions-enabled struct as a member (e.g. AVCodecContext in
114  * libavcodec exports generic options, while its priv_data field exports
115  * codec-specific options). In such a case, it is possible to set up the
116  * parent struct to export a child's options. To do that, simply
117  * implement AVClass.child_next() and AVClass.child_class_next() in the
118  * parent struct's AVClass.
119  * Assuming that the test_struct from above now also contains a
120  * child_struct field:
121  *
122  * @code
123  * typedef struct child_struct {
124  * AVClass *class;
125  * int flags_opt;
126  * } child_struct;
127  * static const AVOption child_opts[] = {
128  * { "test_flags", "This is a test option of flags type.",
129  * offsetof(child_struct, flags_opt), AV_OPT_TYPE_FLAGS, { .i64 = 0 }, INT_MIN, INT_MAX },
130  * { NULL },
131  * };
132  * static const AVClass child_class = {
133  * .class_name = "child class",
134  * .item_name = av_default_item_name,
135  * .option = child_opts,
136  * .version = LIBAVUTIL_VERSION_INT,
137  * };
138  *
139  * void *child_next(void *obj, void *prev)
140  * {
141  * test_struct *t = obj;
142  * if (!prev && t->child_struct)
143  * return t->child_struct;
144  * return NULL
145  * }
146  * const AVClass child_class_next(const AVClass *prev)
147  * {
148  * return prev ? NULL : &child_class;
149  * }
150  * @endcode
151  * Putting child_next() and child_class_next() as defined above into
152  * test_class will now make child_struct's options accessible through
153  * test_struct (again, proper setup as described above needs to be done on
154  * child_struct right after it is created).
155  *
156  * From the above example it might not be clear why both child_next()
157  * and child_class_next() are needed. The distinction is that child_next()
158  * iterates over actually existing objects, while child_class_next()
159  * iterates over all possible child classes. E.g. if an AVCodecContext
160  * was initialized to use a codec which has private options, then its
161  * child_next() will return AVCodecContext.priv_data and finish
162  * iterating. OTOH child_class_next() on AVCodecContext.av_class will
163  * iterate over all available codecs with private options.
164  *
165  * @subsection avoptions_implement_named_constants Named constants
166  * It is possible to create named constants for options. Simply set the unit
167  * field of the option the constants should apply to a string and
168  * create the constants themselves as options of type AV_OPT_TYPE_CONST
169  * with their unit field set to the same string.
170  * Their default_val field should contain the value of the named
171  * constant.
172  * For example, to add some named constants for the test_flags option
173  * above, put the following into the child_opts array:
174  * @code
175  * { "test_flags", "This is a test option of flags type.",
176  * offsetof(child_struct, flags_opt), AV_OPT_TYPE_FLAGS, { .i64 = 0 }, INT_MIN, INT_MAX, "test_unit" },
177  * { "flag1", "This is a flag with value 16", 0, AV_OPT_TYPE_CONST, { .i64 = 16 }, 0, 0, "test_unit" },
178  * @endcode
179  *
180  * @section avoptions_use Using AVOptions
181  * This section deals with accessing options in an AVOptions-enabled struct.
182  * Such structs in FFmpeg are e.g. AVCodecContext in libavcodec or
183  * AVFormatContext in libavformat.
184  *
185  * @subsection avoptions_use_examine Examining AVOptions
186  * The basic functions for examining options are av_opt_next(), which iterates
187  * over all options defined for one object, and av_opt_find(), which searches
188  * for an option with the given name.
189  *
190  * The situation is more complicated with nesting. An AVOptions-enabled struct
191  * may have AVOptions-enabled children. Passing the AV_OPT_SEARCH_CHILDREN flag
192  * to av_opt_find() will make the function search children recursively.
193  *
194  * For enumerating there are basically two cases. The first is when you want to
195  * get all options that may potentially exist on the struct and its children
196  * (e.g. when constructing documentation). In that case you should call
197  * av_opt_child_class_next() recursively on the parent struct's AVClass. The
198  * second case is when you have an already initialized struct with all its
199  * children and you want to get all options that can be actually written or read
200  * from it. In that case you should call av_opt_child_next() recursively (and
201  * av_opt_next() on each result).
202  *
203  * @subsection avoptions_use_get_set Reading and writing AVOptions
204  * When setting options, you often have a string read directly from the
205  * user. In such a case, simply passing it to av_opt_set() is enough. For
206  * non-string type options, av_opt_set() will parse the string according to the
207  * option type.
208  *
209  * Similarly av_opt_get() will read any option type and convert it to a string
210  * which will be returned. Do not forget that the string is allocated, so you
211  * have to free it with av_free().
212  *
213  * In some cases it may be more convenient to put all options into an
214  * AVDictionary and call av_opt_set_dict() on it. A specific case of this
215  * are the format/codec open functions in lavf/lavc which take a dictionary
216  * filled with option as a parameter. This makes it possible to set some options
217  * that cannot be set otherwise, since e.g. the input file format is not known
218  * before the file is actually opened.
219  */
220 
229  AV_OPT_TYPE_BINARY, ///< offset must point to a pointer immediately followed by an int for the length
233  AV_OPT_TYPE_IMAGE_SIZE = MKBETAG('S','I','Z','E'), ///< offset must point to two consecutive integers
234  AV_OPT_TYPE_PIXEL_FMT = MKBETAG('P','F','M','T'),
235  AV_OPT_TYPE_SAMPLE_FMT = MKBETAG('S','F','M','T'),
236  AV_OPT_TYPE_VIDEO_RATE = MKBETAG('V','R','A','T'), ///< offset must point to AVRational
237  AV_OPT_TYPE_DURATION = MKBETAG('D','U','R',' '),
238  AV_OPT_TYPE_COLOR = MKBETAG('C','O','L','R'),
240  AV_OPT_TYPE_BOOL = MKBETAG('B','O','O','L'),
241 };
242 
243 /**
244  * AVOption
245  */
246 typedef struct AVOption {
247  const char *name;
248 
249  /**
250  * short English help text
251  * @todo What about other languages?
252  */
253  const char *help;
254 
255  /**
256  * The offset relative to the context structure where the option
257  * value is stored. It should be 0 for named constants.
258  */
259  int offset;
261 
262  /**
263  * the default value for scalar options
264  */
265  union {
266  int64_t i64;
267  double dbl;
268  const char *str;
269  /* TODO those are unused now */
271  } default_val;
272  double min; ///< minimum valid value for the option
273  double max; ///< maximum valid value for the option
274 
275  int flags;
276 #define AV_OPT_FLAG_ENCODING_PARAM 1 ///< a generic parameter which can be set by the user for muxing or encoding
277 #define AV_OPT_FLAG_DECODING_PARAM 2 ///< a generic parameter which can be set by the user for demuxing or decoding
278 #define AV_OPT_FLAG_AUDIO_PARAM 8
279 #define AV_OPT_FLAG_VIDEO_PARAM 16
280 #define AV_OPT_FLAG_SUBTITLE_PARAM 32
281 /**
282  * The option is intended for exporting values to the caller.
283  */
284 #define AV_OPT_FLAG_EXPORT 64
285 /**
286  * The option may not be set through the AVOptions API, only read.
287  * This flag only makes sense when AV_OPT_FLAG_EXPORT is also set.
288  */
289 #define AV_OPT_FLAG_READONLY 128
290 #define AV_OPT_FLAG_FILTERING_PARAM (1<<16) ///< a generic parameter which can be set by the user for filtering
291 //FIXME think about enc-audio, ... style flags
292 
293  /**
294  * The logical unit to which the option belongs. Non-constant
295  * options and corresponding named constants share the same
296  * unit. May be NULL.
297  */
298  const char *unit;
299 } AVOption;
300 
301 /**
302  * A single allowed range of values, or a single allowed value.
303  */
304 typedef struct AVOptionRange {
305  const char *str;
306  /**
307  * Value range.
308  * For string ranges this represents the min/max length.
309  * For dimensions this represents the min/max pixel count or width/height in multi-component case.
310  */
312  /**
313  * Value's component range.
314  * For string this represents the unicode range for chars, 0-127 limits to ASCII.
315  */
317  /**
318  * Range flag.
319  * If set to 1 the struct encodes a range, if set to 0 a single value.
320  */
321  int is_range;
322 } AVOptionRange;
323 
324 /**
325  * List of AVOptionRange structs.
326  */
327 typedef struct AVOptionRanges {
328  /**
329  * Array of option ranges.
330  *
331  * Most of option types use just one component.
332  * Following describes multi-component option types:
333  *
334  * AV_OPT_TYPE_IMAGE_SIZE:
335  * component index 0: range of pixel count (width * height).
336  * component index 1: range of width.
337  * component index 2: range of height.
338  *
339  * @note To obtain multi-component version of this structure, user must
340  * provide AV_OPT_MULTI_COMPONENT_RANGE to av_opt_query_ranges or
341  * av_opt_query_ranges_default function.
342  *
343  * Multi-component range can be read as in following example:
344  *
345  * @code
346  * int range_index, component_index;
347  * AVOptionRanges *ranges;
348  * AVOptionRange *range[3]; //may require more than 3 in the future.
349  * av_opt_query_ranges(&ranges, obj, key, AV_OPT_MULTI_COMPONENT_RANGE);
350  * for (range_index = 0; range_index < ranges->nb_ranges; range_index++) {
351  * for (component_index = 0; component_index < ranges->nb_components; component_index++)
352  * range[component_index] = ranges->range[ranges->nb_ranges * component_index + range_index];
353  * //do something with range here.
354  * }
355  * av_opt_freep_ranges(&ranges);
356  * @endcode
357  */
359  /**
360  * Number of ranges per component.
361  */
363  /**
364  * Number of componentes.
365  */
368 
369 /**
370  * Show the obj options.
371  *
372  * @param req_flags requested flags for the options to show. Show only the
373  * options for which it is opt->flags & req_flags.
374  * @param rej_flags rejected flags for the options to show. Show only the
375  * options for which it is !(opt->flags & req_flags).
376  * @param av_log_obj log context to use for showing the options
377  */
378 int av_opt_show2(void *obj, void *av_log_obj, int req_flags, int rej_flags);
379 
380 /**
381  * Set the values of all AVOption fields to their default values.
382  *
383  * @param s an AVOption-enabled struct (its first member must be a pointer to AVClass)
384  */
385 void av_opt_set_defaults(void *s);
386 
387 /**
388  * Set the values of all AVOption fields to their default values. Only these
389  * AVOption fields for which (opt->flags & mask) == flags will have their
390  * default applied to s.
391  *
392  * @param s an AVOption-enabled struct (its first member must be a pointer to AVClass)
393  * @param mask combination of AV_OPT_FLAG_*
394  * @param flags combination of AV_OPT_FLAG_*
395  */
396 void av_opt_set_defaults2(void *s, int mask, int flags);
397 
398 /**
399  * Parse the key/value pairs list in opts. For each key/value pair
400  * found, stores the value in the field in ctx that is named like the
401  * key. ctx must be an AVClass context, storing is done using
402  * AVOptions.
403  *
404  * @param opts options string to parse, may be NULL
405  * @param key_val_sep a 0-terminated list of characters used to
406  * separate key from value
407  * @param pairs_sep a 0-terminated list of characters used to separate
408  * two pairs from each other
409  * @return the number of successfully set key/value pairs, or a negative
410  * value corresponding to an AVERROR code in case of error:
411  * AVERROR(EINVAL) if opts cannot be parsed,
412  * the error code issued by av_opt_set() if a key/value pair
413  * cannot be set
414  */
415 int av_set_options_string(void *ctx, const char *opts,
416  const char *key_val_sep, const char *pairs_sep);
417 
418 /**
419  * Parse the key-value pairs list in opts. For each key=value pair found,
420  * set the value of the corresponding option in ctx.
421  *
422  * @param ctx the AVClass object to set options on
423  * @param opts the options string, key-value pairs separated by a
424  * delimiter
425  * @param shorthand a NULL-terminated array of options names for shorthand
426  * notation: if the first field in opts has no key part,
427  * the key is taken from the first element of shorthand;
428  * then again for the second, etc., until either opts is
429  * finished, shorthand is finished or a named option is
430  * found; after that, all options must be named
431  * @param key_val_sep a 0-terminated list of characters used to separate
432  * key from value, for example '='
433  * @param pairs_sep a 0-terminated list of characters used to separate
434  * two pairs from each other, for example ':' or ','
435  * @return the number of successfully set key=value pairs, or a negative
436  * value corresponding to an AVERROR code in case of error:
437  * AVERROR(EINVAL) if opts cannot be parsed,
438  * the error code issued by av_set_string3() if a key/value pair
439  * cannot be set
440  *
441  * Options names must use only the following characters: a-z A-Z 0-9 - . / _
442  * Separators must use characters distinct from option names and from each
443  * other.
444  */
445 int av_opt_set_from_string(void *ctx, const char *opts,
446  const char *const *shorthand,
447  const char *key_val_sep, const char *pairs_sep);
448 /**
449  * Free all allocated objects in obj.
450  */
451 void av_opt_free(void *obj);
452 
453 /**
454  * Check whether a particular flag is set in a flags field.
455  *
456  * @param field_name the name of the flag field option
457  * @param flag_name the name of the flag to check
458  * @return non-zero if the flag is set, zero if the flag isn't set,
459  * isn't of the right type, or the flags field doesn't exist.
460  */
461 int av_opt_flag_is_set(void *obj, const char *field_name, const char *flag_name);
462 
463 /**
464  * Set all the options from a given dictionary on an object.
465  *
466  * @param obj a struct whose first element is a pointer to AVClass
467  * @param options options to process. This dictionary will be freed and replaced
468  * by a new one containing all options not found in obj.
469  * Of course this new dictionary needs to be freed by caller
470  * with av_dict_free().
471  *
472  * @return 0 on success, a negative AVERROR if some option was found in obj,
473  * but could not be set.
474  *
475  * @see av_dict_copy()
476  */
477 int av_opt_set_dict(void *obj, struct AVDictionary **options);
478 
479 
480 /**
481  * Set all the options from a given dictionary on an object.
482  *
483  * @param obj a struct whose first element is a pointer to AVClass
484  * @param options options to process. This dictionary will be freed and replaced
485  * by a new one containing all options not found in obj.
486  * Of course this new dictionary needs to be freed by caller
487  * with av_dict_free().
488  * @param search_flags A combination of AV_OPT_SEARCH_*.
489  *
490  * @return 0 on success, a negative AVERROR if some option was found in obj,
491  * but could not be set.
492  *
493  * @see av_dict_copy()
494  */
495 int av_opt_set_dict2(void *obj, struct AVDictionary **options, int search_flags);
496 
497 /**
498  * Extract a key-value pair from the beginning of a string.
499  *
500  * @param ropts pointer to the options string, will be updated to
501  * point to the rest of the string (one of the pairs_sep
502  * or the final NUL)
503  * @param key_val_sep a 0-terminated list of characters used to separate
504  * key from value, for example '='
505  * @param pairs_sep a 0-terminated list of characters used to separate
506  * two pairs from each other, for example ':' or ','
507  * @param flags flags; see the AV_OPT_FLAG_* values below
508  * @param rkey parsed key; must be freed using av_free()
509  * @param rval parsed value; must be freed using av_free()
510  *
511  * @return >=0 for success, or a negative value corresponding to an
512  * AVERROR code in case of error; in particular:
513  * AVERROR(EINVAL) if no key is present
514  *
515  */
516 int av_opt_get_key_value(const char **ropts,
517  const char *key_val_sep, const char *pairs_sep,
518  unsigned flags,
519  char **rkey, char **rval);
520 
521 enum {
522 
523  /**
524  * Accept to parse a value without a key; the key will then be returned
525  * as NULL.
526  */
528 };
529 
530 /**
531  * @defgroup opt_eval_funcs Evaluating option strings
532  * @{
533  * This group of functions can be used to evaluate option strings
534  * and get numbers out of them. They do the same thing as av_opt_set(),
535  * except the result is written into the caller-supplied pointer.
536  *
537  * @param obj a struct whose first element is a pointer to AVClass.
538  * @param o an option for which the string is to be evaluated.
539  * @param val string to be evaluated.
540  * @param *_out value of the string will be written here.
541  *
542  * @return 0 on success, a negative number on failure.
543  */
544 int av_opt_eval_flags (void *obj, const AVOption *o, const char *val, int *flags_out);
545 int av_opt_eval_int (void *obj, const AVOption *o, const char *val, int *int_out);
546 int av_opt_eval_int64 (void *obj, const AVOption *o, const char *val, int64_t *int64_out);
547 int av_opt_eval_float (void *obj, const AVOption *o, const char *val, float *float_out);
548 int av_opt_eval_double(void *obj, const AVOption *o, const char *val, double *double_out);
549 int av_opt_eval_q (void *obj, const AVOption *o, const char *val, AVRational *q_out);
550 /**
551  * @}
552  */
553 
554 #define AV_OPT_SEARCH_CHILDREN (1 << 0) /**< Search in possible children of the
555  given object first. */
556 /**
557  * The obj passed to av_opt_find() is fake -- only a double pointer to AVClass
558  * instead of a required pointer to a struct containing AVClass. This is
559  * useful for searching for options without needing to allocate the corresponding
560  * object.
561  */
562 #define AV_OPT_SEARCH_FAKE_OBJ (1 << 1)
564 /**
565  * In av_opt_get, return NULL if the option has a pointer type and is set to NULL,
566  * rather than returning an empty string.
567  */
568 #define AV_OPT_ALLOW_NULL (1 << 2)
570 /**
571  * Allows av_opt_query_ranges and av_opt_query_ranges_default to return more than
572  * one component for certain option types.
573  * @see AVOptionRanges for details.
574  */
575 #define AV_OPT_MULTI_COMPONENT_RANGE (1 << 12)
577 /**
578  * Look for an option in an object. Consider only options which
579  * have all the specified flags set.
580  *
581  * @param[in] obj A pointer to a struct whose first element is a
582  * pointer to an AVClass.
583  * Alternatively a double pointer to an AVClass, if
584  * AV_OPT_SEARCH_FAKE_OBJ search flag is set.
585  * @param[in] name The name of the option to look for.
586  * @param[in] unit When searching for named constants, name of the unit
587  * it belongs to.
588  * @param opt_flags Find only options with all the specified flags set (AV_OPT_FLAG).
589  * @param search_flags A combination of AV_OPT_SEARCH_*.
590  *
591  * @return A pointer to the option found, or NULL if no option
592  * was found.
593  *
594  * @note Options found with AV_OPT_SEARCH_CHILDREN flag may not be settable
595  * directly with av_opt_set(). Use special calls which take an options
596  * AVDictionary (e.g. avformat_open_input()) to set options found with this
597  * flag.
598  */
599 const AVOption *av_opt_find(void *obj, const char *name, const char *unit,
600  int opt_flags, int search_flags);
601 
602 /**
603  * Look for an option in an object. Consider only options which
604  * have all the specified flags set.
605  *
606  * @param[in] obj A pointer to a struct whose first element is a
607  * pointer to an AVClass.
608  * Alternatively a double pointer to an AVClass, if
609  * AV_OPT_SEARCH_FAKE_OBJ search flag is set.
610  * @param[in] name The name of the option to look for.
611  * @param[in] unit When searching for named constants, name of the unit
612  * it belongs to.
613  * @param opt_flags Find only options with all the specified flags set (AV_OPT_FLAG).
614  * @param search_flags A combination of AV_OPT_SEARCH_*.
615  * @param[out] target_obj if non-NULL, an object to which the option belongs will be
616  * written here. It may be different from obj if AV_OPT_SEARCH_CHILDREN is present
617  * in search_flags. This parameter is ignored if search_flags contain
618  * AV_OPT_SEARCH_FAKE_OBJ.
619  *
620  * @return A pointer to the option found, or NULL if no option
621  * was found.
622  */
623 const AVOption *av_opt_find2(void *obj, const char *name, const char *unit,
624  int opt_flags, int search_flags, void **target_obj);
625 
626 /**
627  * Iterate over all AVOptions belonging to obj.
628  *
629  * @param obj an AVOptions-enabled struct or a double pointer to an
630  * AVClass describing it.
631  * @param prev result of the previous call to av_opt_next() on this object
632  * or NULL
633  * @return next AVOption or NULL
634  */
635 const AVOption *av_opt_next(const void *obj, const AVOption *prev);
636 
637 /**
638  * Iterate over AVOptions-enabled children of obj.
639  *
640  * @param prev result of a previous call to this function or NULL
641  * @return next AVOptions-enabled child or NULL
642  */
643 void *av_opt_child_next(void *obj, void *prev);
644 
645 /**
646  * Iterate over potential AVOptions-enabled children of parent.
647  *
648  * @param prev result of a previous call to this function or NULL
649  * @return AVClass corresponding to next potential child or NULL
650  */
651 const AVClass *av_opt_child_class_next(const AVClass *parent, const AVClass *prev);
652 
653 /**
654  * @defgroup opt_set_funcs Option setting functions
655  * @{
656  * Those functions set the field of obj with the given name to value.
657  *
658  * @param[in] obj A struct whose first element is a pointer to an AVClass.
659  * @param[in] name the name of the field to set
660  * @param[in] val The value to set. In case of av_opt_set() if the field is not
661  * of a string type, then the given string is parsed.
662  * SI postfixes and some named scalars are supported.
663  * If the field is of a numeric type, it has to be a numeric or named
664  * scalar. Behavior with more than one scalar and +- infix operators
665  * is undefined.
666  * If the field is of a flags type, it has to be a sequence of numeric
667  * scalars or named flags separated by '+' or '-'. Prefixing a flag
668  * with '+' causes it to be set without affecting the other flags;
669  * similarly, '-' unsets a flag.
670  * @param search_flags flags passed to av_opt_find2. I.e. if AV_OPT_SEARCH_CHILDREN
671  * is passed here, then the option may be set on a child of obj.
672  *
673  * @return 0 if the value has been set, or an AVERROR code in case of
674  * error:
675  * AVERROR_OPTION_NOT_FOUND if no matching option exists
676  * AVERROR(ERANGE) if the value is out of range
677  * AVERROR(EINVAL) if the value is not valid
678  */
679 int av_opt_set (void *obj, const char *name, const char *val, int search_flags);
680 int av_opt_set_int (void *obj, const char *name, int64_t val, int search_flags);
681 int av_opt_set_double (void *obj, const char *name, double val, int search_flags);
682 int av_opt_set_q (void *obj, const char *name, AVRational val, int search_flags);
683 int av_opt_set_bin (void *obj, const char *name, const uint8_t *val, int size, int search_flags);
684 int av_opt_set_image_size(void *obj, const char *name, int w, int h, int search_flags);
685 int av_opt_set_pixel_fmt (void *obj, const char *name, enum AVPixelFormat fmt, int search_flags);
686 int av_opt_set_sample_fmt(void *obj, const char *name, enum AVSampleFormat fmt, int search_flags);
687 int av_opt_set_video_rate(void *obj, const char *name, AVRational val, int search_flags);
688 int av_opt_set_channel_layout(void *obj, const char *name, int64_t ch_layout, int search_flags);
689 /**
690  * @note Any old dictionary present is discarded and replaced with a copy of the new one. The
691  * caller still owns val is and responsible for freeing it.
692  */
693 int av_opt_set_dict_val(void *obj, const char *name, const AVDictionary *val, int search_flags);
694 
695 /**
696  * Set a binary option to an integer list.
697  *
698  * @param obj AVClass object to set options on
699  * @param name name of the binary option
700  * @param val pointer to an integer list (must have the correct type with
701  * regard to the contents of the list)
702  * @param term list terminator (usually 0 or -1)
703  * @param flags search flags
704  */
705 #define av_opt_set_int_list(obj, name, val, term, flags) \
706  (av_int_list_length(val, term) > INT_MAX / sizeof(*(val)) ? \
707  AVERROR(EINVAL) : \
708  av_opt_set_bin(obj, name, (const uint8_t *)(val), \
709  av_int_list_length(val, term) * sizeof(*(val)), flags))
710 
711 /**
712  * @}
713  */
714 
715 /**
716  * @defgroup opt_get_funcs Option getting functions
717  * @{
718  * Those functions get a value of the option with the given name from an object.
719  *
720  * @param[in] obj a struct whose first element is a pointer to an AVClass.
721  * @param[in] name name of the option to get.
722  * @param[in] search_flags flags passed to av_opt_find2. I.e. if AV_OPT_SEARCH_CHILDREN
723  * is passed here, then the option may be found in a child of obj.
724  * @param[out] out_val value of the option will be written here
725  * @return >=0 on success, a negative error code otherwise
726  */
727 /**
728  * @note the returned string will be av_malloc()ed and must be av_free()ed by the caller
729  *
730  * @note if AV_OPT_ALLOW_NULL is set in search_flags in av_opt_get, and the option has
731  * AV_OPT_TYPE_STRING or AV_OPT_TYPE_BINARY and is set to NULL, *out_val will be set
732  * to NULL instead of an allocated empty string.
733  */
734 int av_opt_get (void *obj, const char *name, int search_flags, uint8_t **out_val);
735 int av_opt_get_int (void *obj, const char *name, int search_flags, int64_t *out_val);
736 int av_opt_get_double (void *obj, const char *name, int search_flags, double *out_val);
737 int av_opt_get_q (void *obj, const char *name, int search_flags, AVRational *out_val);
738 int av_opt_get_image_size(void *obj, const char *name, int search_flags, int *w_out, int *h_out);
739 int av_opt_get_pixel_fmt (void *obj, const char *name, int search_flags, enum AVPixelFormat *out_fmt);
740 int av_opt_get_sample_fmt(void *obj, const char *name, int search_flags, enum AVSampleFormat *out_fmt);
741 int av_opt_get_video_rate(void *obj, const char *name, int search_flags, AVRational *out_val);
742 int av_opt_get_channel_layout(void *obj, const char *name, int search_flags, int64_t *ch_layout);
743 /**
744  * @param[out] out_val The returned dictionary is a copy of the actual value and must
745  * be freed with av_dict_free() by the caller
746  */
747 int av_opt_get_dict_val(void *obj, const char *name, int search_flags, AVDictionary **out_val);
748 /**
749  * @}
750  */
751 /**
752  * Gets a pointer to the requested field in a struct.
753  * This function allows accessing a struct even when its fields are moved or
754  * renamed since the application making the access has been compiled,
755  *
756  * @returns a pointer to the field, it can be cast to the correct type and read
757  * or written to.
758  */
759 void *av_opt_ptr(const AVClass *avclass, void *obj, const char *name);
760 
761 /**
762  * Free an AVOptionRanges struct and set it to NULL.
763  */
764 void av_opt_freep_ranges(AVOptionRanges **ranges);
765 
766 /**
767  * Get a list of allowed ranges for the given option.
768  *
769  * The returned list may depend on other fields in obj like for example profile.
770  *
771  * @param flags is a bitmask of flags, undefined flags should not be set and should be ignored
772  * AV_OPT_SEARCH_FAKE_OBJ indicates that the obj is a double pointer to a AVClass instead of a full instance
773  * AV_OPT_MULTI_COMPONENT_RANGE indicates that function may return more than one component, @see AVOptionRanges
774  *
775  * The result must be freed with av_opt_freep_ranges.
776  *
777  * @return number of compontents returned on success, a negative errro code otherwise
778  */
779 int av_opt_query_ranges(AVOptionRanges **, void *obj, const char *key, int flags);
780 
781 /**
782  * Copy options from src object into dest object.
783  *
784  * Options that require memory allocation (e.g. string or binary) are malloc'ed in dest object.
785  * Original memory allocated for such options is freed unless both src and dest options points to the same memory.
786  *
787  * @param dest Object to copy from
788  * @param src Object to copy into
789  * @return 0 on success, negative on error
790  */
791 int av_opt_copy(void *dest, const void *src);
792 
793 /**
794  * Get a default list of allowed ranges for the given option.
795  *
796  * This list is constructed without using the AVClass.query_ranges() callback
797  * and can be used as fallback from within the callback.
798  *
799  * @param flags is a bitmask of flags, undefined flags should not be set and should be ignored
800  * AV_OPT_SEARCH_FAKE_OBJ indicates that the obj is a double pointer to a AVClass instead of a full instance
801  * AV_OPT_MULTI_COMPONENT_RANGE indicates that function may return more than one component, @see AVOptionRanges
802  *
803  * The result must be freed with av_opt_free_ranges.
804  *
805  * @return number of compontents returned on success, a negative errro code otherwise
806  */
807 int av_opt_query_ranges_default(AVOptionRanges **, void *obj, const char *key, int flags);
808 
809 /**
810  * Check if given option is set to its default value.
811  *
812  * Options o must belong to the obj. This function must not be called to check child's options state.
813  * @see av_opt_is_set_to_default_by_name().
814  *
815  * @param obj AVClass object to check option on
816  * @param o option to be checked
817  * @return >0 when option is set to its default,
818  * 0 when option is not set its default,
819  * <0 on error
820  */
821 int av_opt_is_set_to_default(void *obj, const AVOption *o);
822 
823 /**
824  * Check if given option is set to its default value.
825  *
826  * @param obj AVClass object to check option on
827  * @param name option name
828  * @param search_flags combination of AV_OPT_SEARCH_*
829  * @return >0 when option is set to its default,
830  * 0 when option is not set its default,
831  * <0 on error
832  */
833 int av_opt_is_set_to_default_by_name(void *obj, const char *name, int search_flags);
834 
835 
836 #define AV_OPT_SERIALIZE_SKIP_DEFAULTS 0x00000001 ///< Serialize options that are not set to default values only.
837 #define AV_OPT_SERIALIZE_OPT_FLAGS_EXACT 0x00000002 ///< Serialize options that exactly match opt_flags only.
839 /**
840  * Serialize object's options.
841  *
842  * Create a string containing object's serialized options.
843  * Such string may be passed back to av_opt_set_from_string() in order to restore option values.
844  * A key/value or pairs separator occurring in the serialized value or
845  * name string are escaped through the av_escape() function.
846  *
847  * @param[in] obj AVClass object to serialize
848  * @param[in] opt_flags serialize options with all the specified flags set (AV_OPT_FLAG)
849  * @param[in] flags combination of AV_OPT_SERIALIZE_* flags
850  * @param[out] buffer Pointer to buffer that will be allocated with string containg serialized options.
851  * Buffer must be freed by the caller when is no longer needed.
852  * @param[in] key_val_sep character used to separate key from value
853  * @param[in] pairs_sep character used to separate two pairs from each other
854  * @return >= 0 on success, negative on error
855  * @warning Separators cannot be neither '\\' nor '\0'. They also cannot be the same.
856  */
857 int av_opt_serialize(void *obj, int opt_flags, int flags, char **buffer,
858  const char key_val_sep, const char pairs_sep);
859 /**
860  * @}
861  */
862 
863 #endif /* AVUTIL_OPT_H */
int av_opt_get_dict_val(void *obj, const char *name, int search_flags, AVDictionary **out_val)
Definition: opt.c:994
const char const char void * val
Definition: avisynth_c.h:771
A single allowed range of values, or a single allowed value.
Definition: opt.h:304
int av_opt_eval_float(void *obj, const AVOption *o, const char *val, float *float_out)
const char * s
Definition: avisynth_c.h:768
AVOption.
Definition: opt.h:246
int av_opt_set_q(void *obj, const char *name, AVRational val, int search_flags)
Definition: opt.c:568
const char * fmt
Definition: avisynth_c.h:769
void * av_opt_child_next(void *obj, void *prev)
Iterate over AVOptions-enabled children of obj.
Definition: opt.c:1644
double value_max
Definition: opt.h:311
const AVClass * av_opt_child_class_next(const AVClass *parent, const AVClass *prev)
Iterate over potential AVOptions-enabled children of parent.
Definition: opt.c:1652
void av_opt_set_defaults(void *s)
Set the values of all AVOption fields to their default values.
Definition: opt.c:1291
int av_set_options_string(void *ctx, const char *opts, const char *key_val_sep, const char *pairs_sep)
Parse the key/value pairs list in opts.
Definition: opt.c:1412
Convenience header that includes libavutil's core.
int av_opt_set_bin(void *obj, const char *name, const uint8_t *val, int size, int search_flags)
Definition: opt.c:573
const char * key
int av_opt_get_q(void *obj, const char *name, int search_flags, AVRational *out_val)
Definition: opt.c:899
int av_opt_serialize(void *obj, int opt_flags, int flags, char **buffer, const char key_val_sep, const char pairs_sep)
Serialize object's options.
Definition: opt.c:1980
int av_opt_set_dict_val(void *obj, const char *name, const AVDictionary *val, int search_flags)
Definition: opt.c:697
#define src
Definition: vp8dsp.c:254
AVOptionType
Definition: opt.h:221
int av_opt_is_set_to_default_by_name(void *obj, const char *name, int search_flags)
Check if given option is set to its default value.
Definition: opt.c:1968
AVRational q
Definition: opt.h:270
int av_opt_is_set_to_default(void *obj, const AVOption *o)
Check if given option is set to its default value.
Definition: opt.c:1871
int av_opt_get_video_rate(void *obj, const char *name, int search_flags, AVRational *out_val)
Definition: opt.c:933
int av_opt_set_from_string(void *ctx, const char *opts, const char *const *shorthand, const char *key_val_sep, const char *pairs_sep)
Parse the key-value pairs list in opts.
Definition: opt.c:1492
Public dictionary API.
const char * name
Definition: opt.h:247
uint8_t
AVOptionRange ** range
Array of option ranges.
Definition: opt.h:358
const char * help
short English help text
Definition: opt.h:253
const char * str
Definition: opt.h:268
int av_opt_eval_int64(void *obj, const AVOption *o, const char *val, int64_t *int64_out)
int av_opt_set_double(void *obj, const char *name, double val, int search_flags)
Definition: opt.c:563
static int flags
Definition: log.c:57
double component_max
Definition: opt.h:316
union AVOption::@274 default_val
the default value for scalar options
ptrdiff_t size
Definition: opengl_enc.c:101
const OptionDef options[]
Definition: ffserver.c:3948
int av_opt_set_video_rate(void *obj, const char *name, AVRational val, int search_flags)
Definition: opt.c:625
int av_opt_get_pixel_fmt(void *obj, const char *name, int search_flags, enum AVPixelFormat *out_fmt)
Definition: opt.c:967
int av_opt_set_pixel_fmt(void *obj, const char *name, enum AVPixelFormat fmt, int search_flags)
Definition: opt.c:671
void * av_opt_ptr(const AVClass *avclass, void *obj, const char *name)
Gets a pointer to the requested field in a struct.
Definition: opt.c:1659
static const uint16_t mask[17]
Definition: lzw.c:38
double max
maximum valid value for the option
Definition: opt.h:273
int av_opt_eval_flags(void *obj, const AVOption *o, const char *val, int *flags_out)
int av_opt_set_int(void *obj, const char *name, int64_t val, int search_flags)
Definition: opt.c:558
const AVOption * av_opt_next(const void *obj, const AVOption *prev)
Iterate over all AVOptions belonging to obj.
Definition: opt.c:45
Accept to parse a value without a key; the key will then be returned as NULL.
Definition: opt.h:527
Libavutil version macros.
const AVOption * av_opt_find(void *obj, const char *name, const char *unit, int opt_flags, int search_flags)
Look for an option in an object.
Definition: opt.c:1594
int av_opt_eval_double(void *obj, const AVOption *o, const char *val, double *double_out)
AVDictionary * opts
Definition: movenc.c:50
int av_opt_get_sample_fmt(void *obj, const char *name, int search_flags, enum AVSampleFormat *out_fmt)
Definition: opt.c:972
const char * str
Definition: opt.h:305
AVFormatContext * ctx
Definition: movenc.c:48
const char * unit
The logical unit to which the option belongs.
Definition: opt.h:298
double component_min
Value's component range.
Definition: opt.h:316
int av_opt_eval_q(void *obj, const AVOption *o, const char *val, AVRational *q_out)
int av_opt_set_channel_layout(void *obj, const char *name, int64_t ch_layout, int search_flags)
Definition: opt.c:681
double min
minimum valid value for the option
Definition: opt.h:272
void av_opt_set_defaults2(void *s, int mask, int flags)
Set the values of all AVOption fields to their default values.
Definition: opt.c:1296
int av_opt_set_dict2(void *obj, struct AVDictionary **options, int search_flags)
Set all the options from a given dictionary on an object.
Definition: opt.c:1564
offset must point to a pointer immediately followed by an int for the length
Definition: opt.h:229
int flags
Definition: opt.h:275
int av_opt_query_ranges_default(AVOptionRanges **, void *obj, const char *key, int flags)
Get a default list of allowed ranges for the given option.
Definition: opt.c:1780
int is_range
Range flag.
Definition: opt.h:321
int av_opt_get_int(void *obj, const char *name, int search_flags, int64_t *out_val)
Definition: opt.c:875
void av_opt_freep_ranges(AVOptionRanges **ranges)
Free an AVOptionRanges struct and set it to NULL.
Definition: opt.c:1852
int offset
The offset relative to the context structure where the option value is stored.
Definition: opt.h:259
AVSampleFormat
Audio sample formats.
Definition: samplefmt.h:58
int av_opt_set_dict(void *obj, struct AVDictionary **options)
Set all the options from a given dictionary on an object.
Definition: opt.c:1589
int av_opt_show2(void *obj, void *av_log_obj, int req_flags, int rej_flags)
Show the obj options.
Definition: opt.c:1279
int av_opt_get_channel_layout(void *obj, const char *name, int search_flags, int64_t *ch_layout)
Definition: opt.c:977
Describe the class of an AVClass context structure.
Definition: log.h:67
Rational number (pair of numerator and denominator).
Definition: rational.h:58
double dbl
Definition: opt.h:267
offset must point to AVRational
Definition: opt.h:236
int av_opt_eval_int(void *obj, const AVOption *o, const char *val, int *int_out)
offset must point to two consecutive integers
Definition: opt.h:233
void av_opt_free(void *obj)
Free all allocated objects in obj.
Definition: opt.c:1544
int av_opt_query_ranges(AVOptionRanges **, void *obj, const char *key, int flags)
Get a list of allowed ranges for the given option.
Definition: opt.c:1759
double value_min
Value range.
Definition: opt.h:311
Utilties for rational number calculation.
int av_opt_get_double(void *obj, const char *name, int search_flags, double *out_val)
Definition: opt.c:887
int av_opt_copy(void *dest, const void *src)
Copy options from src object into dest object.
Definition: opt.c:1702
int nb_ranges
Number of ranges per component.
Definition: opt.h:362
#define MKBETAG(a, b, c, d)
Definition: common.h:367
List of AVOptionRange structs.
Definition: opt.h:327
pixel format definitions
int av_opt_get(void *obj, const char *name, int search_flags, uint8_t **out_val)
Definition: opt.c:751
enum AVOptionType type
Definition: opt.h:260
int av_opt_get_key_value(const char **ropts, const char *key_val_sep, const char *pairs_sep, unsigned flags, char **rkey, char **rval)
Extract a key-value pair from the beginning of a string.
Definition: opt.c:1470
int64_t i64
Definition: opt.h:266
int av_opt_flag_is_set(void *obj, const char *field_name, const char *flag_name)
Check whether a particular flag is set in a flags field.
Definition: opt.c:1011
const AVOption * av_opt_find2(void *obj, const char *name, const char *unit, int opt_flags, int search_flags, void **target_obj)
Look for an option in an object.
Definition: opt.c:1600
int av_opt_set_sample_fmt(void *obj, const char *name, enum AVSampleFormat fmt, int search_flags)
Definition: opt.c:676
AVPixelFormat
Pixel format.
Definition: pixfmt.h:60
int av_opt_set_image_size(void *obj, const char *name, int w, int h, int search_flags)
Definition: opt.c:603
int av_opt_set(void *obj, const char *name, const char *val, int search_flags)
Definition: opt.c:449
GLuint buffer
Definition: opengl_enc.c:102
const char * name
Definition: opengl_enc.c:103
int nb_components
Number of componentes.
Definition: opt.h:366
int av_opt_get_image_size(void *obj, const char *name, int search_flags, int *w_out, int *h_out)
Definition: opt.c:915