FFmpeg
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 "channel_layout.h"
33 #include "dict.h"
34 #include "log.h"
35 #include "pixfmt.h"
36 #include "samplefmt.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_iterate() 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_iterate(void **iter)
147  * {
148  * const AVClass *c = *iter ? NULL : &child_class;
149  * *iter = (void*)(uintptr_t)c;
150  * return c;
151  * }
152  * @endcode
153  * Putting child_next() and child_class_iterate() as defined above into
154  * test_class will now make child_struct's options accessible through
155  * test_struct (again, proper setup as described above needs to be done on
156  * child_struct right after it is created).
157  *
158  * From the above example it might not be clear why both child_next()
159  * and child_class_iterate() are needed. The distinction is that child_next()
160  * iterates over actually existing objects, while child_class_iterate()
161  * iterates over all possible child classes. E.g. if an AVCodecContext
162  * was initialized to use a codec which has private options, then its
163  * child_next() will return AVCodecContext.priv_data and finish
164  * iterating. OTOH child_class_iterate() on AVCodecContext.av_class will
165  * iterate over all available codecs with private options.
166  *
167  * @subsection avoptions_implement_named_constants Named constants
168  * It is possible to create named constants for options. Simply set the unit
169  * field of the option the constants should apply to a string and
170  * create the constants themselves as options of type AV_OPT_TYPE_CONST
171  * with their unit field set to the same string.
172  * Their default_val field should contain the value of the named
173  * constant.
174  * For example, to add some named constants for the test_flags option
175  * above, put the following into the child_opts array:
176  * @code
177  * { "test_flags", "This is a test option of flags type.",
178  * offsetof(child_struct, flags_opt), AV_OPT_TYPE_FLAGS, { .i64 = 0 }, INT_MIN, INT_MAX, "test_unit" },
179  * { "flag1", "This is a flag with value 16", 0, AV_OPT_TYPE_CONST, { .i64 = 16 }, 0, 0, "test_unit" },
180  * @endcode
181  *
182  * @section avoptions_use Using AVOptions
183  * This section deals with accessing options in an AVOptions-enabled struct.
184  * Such structs in FFmpeg are e.g. AVCodecContext in libavcodec or
185  * AVFormatContext in libavformat.
186  *
187  * @subsection avoptions_use_examine Examining AVOptions
188  * The basic functions for examining options are av_opt_next(), which iterates
189  * over all options defined for one object, and av_opt_find(), which searches
190  * for an option with the given name.
191  *
192  * The situation is more complicated with nesting. An AVOptions-enabled struct
193  * may have AVOptions-enabled children. Passing the AV_OPT_SEARCH_CHILDREN flag
194  * to av_opt_find() will make the function search children recursively.
195  *
196  * For enumerating there are basically two cases. The first is when you want to
197  * get all options that may potentially exist on the struct and its children
198  * (e.g. when constructing documentation). In that case you should call
199  * av_opt_child_class_iterate() recursively on the parent struct's AVClass. The
200  * second case is when you have an already initialized struct with all its
201  * children and you want to get all options that can be actually written or read
202  * from it. In that case you should call av_opt_child_next() recursively (and
203  * av_opt_next() on each result).
204  *
205  * @subsection avoptions_use_get_set Reading and writing AVOptions
206  * When setting options, you often have a string read directly from the
207  * user. In such a case, simply passing it to av_opt_set() is enough. For
208  * non-string type options, av_opt_set() will parse the string according to the
209  * option type.
210  *
211  * Similarly av_opt_get() will read any option type and convert it to a string
212  * which will be returned. Do not forget that the string is allocated, so you
213  * have to free it with av_free().
214  *
215  * In some cases it may be more convenient to put all options into an
216  * AVDictionary and call av_opt_set_dict() on it. A specific case of this
217  * are the format/codec open functions in lavf/lavc which take a dictionary
218  * filled with option as a parameter. This makes it possible to set some options
219  * that cannot be set otherwise, since e.g. the input file format is not known
220  * before the file is actually opened.
221  */
222 
231  AV_OPT_TYPE_BINARY, ///< offset must point to a pointer immediately followed by an int for the length
235  AV_OPT_TYPE_IMAGE_SIZE, ///< offset must point to two consecutive integers
238  AV_OPT_TYPE_VIDEO_RATE, ///< offset must point to AVRational
241 #if FF_API_OLD_CHANNEL_LAYOUT
243 #endif
246 };
247 
248 /**
249  * AVOption
250  */
251 typedef struct AVOption {
252  const char *name;
253 
254  /**
255  * short English help text
256  * @todo What about other languages?
257  */
258  const char *help;
259 
260  /**
261  * The offset relative to the context structure where the option
262  * value is stored. It should be 0 for named constants.
263  */
264  int offset;
265  enum AVOptionType type;
266 
267  /**
268  * the default value for scalar options
269  */
270  union {
271  int64_t i64;
272  double dbl;
273  const char *str;
274  /* TODO those are unused now */
277  double min; ///< minimum valid value for the option
278  double max; ///< maximum valid value for the option
279 
280  int flags;
281 #define AV_OPT_FLAG_ENCODING_PARAM 1 ///< a generic parameter which can be set by the user for muxing or encoding
282 #define AV_OPT_FLAG_DECODING_PARAM 2 ///< a generic parameter which can be set by the user for demuxing or decoding
283 #define AV_OPT_FLAG_AUDIO_PARAM 8
284 #define AV_OPT_FLAG_VIDEO_PARAM 16
285 #define AV_OPT_FLAG_SUBTITLE_PARAM 32
286 /**
287  * The option is intended for exporting values to the caller.
288  */
289 #define AV_OPT_FLAG_EXPORT 64
290 /**
291  * The option may not be set through the AVOptions API, only read.
292  * This flag only makes sense when AV_OPT_FLAG_EXPORT is also set.
293  */
294 #define AV_OPT_FLAG_READONLY 128
295 #define AV_OPT_FLAG_BSF_PARAM (1<<8) ///< a generic parameter which can be set by the user for bit stream filtering
296 #define AV_OPT_FLAG_RUNTIME_PARAM (1<<15) ///< a generic parameter which can be set by the user at runtime
297 #define AV_OPT_FLAG_FILTERING_PARAM (1<<16) ///< a generic parameter which can be set by the user for filtering
298 #define AV_OPT_FLAG_DEPRECATED (1<<17) ///< set if option is deprecated, users should refer to AVOption.help text for more information
299 #define AV_OPT_FLAG_CHILD_CONSTS (1<<18) ///< set if option constants can also reside in child objects
300 //FIXME think about enc-audio, ... style flags
301 
302  /**
303  * The logical unit to which the option belongs. Non-constant
304  * options and corresponding named constants share the same
305  * unit. May be NULL.
306  */
307  const char *unit;
308 } AVOption;
309 
310 /**
311  * A single allowed range of values, or a single allowed value.
312  */
313 typedef struct AVOptionRange {
314  const char *str;
315  /**
316  * Value range.
317  * For string ranges this represents the min/max length.
318  * For dimensions this represents the min/max pixel count or width/height in multi-component case.
319  */
321  /**
322  * Value's component range.
323  * For string this represents the unicode range for chars, 0-127 limits to ASCII.
324  */
326  /**
327  * Range flag.
328  * If set to 1 the struct encodes a range, if set to 0 a single value.
329  */
330  int is_range;
331 } AVOptionRange;
332 
333 /**
334  * List of AVOptionRange structs.
335  */
336 typedef struct AVOptionRanges {
337  /**
338  * Array of option ranges.
339  *
340  * Most of option types use just one component.
341  * Following describes multi-component option types:
342  *
343  * AV_OPT_TYPE_IMAGE_SIZE:
344  * component index 0: range of pixel count (width * height).
345  * component index 1: range of width.
346  * component index 2: range of height.
347  *
348  * @note To obtain multi-component version of this structure, user must
349  * provide AV_OPT_MULTI_COMPONENT_RANGE to av_opt_query_ranges or
350  * av_opt_query_ranges_default function.
351  *
352  * Multi-component range can be read as in following example:
353  *
354  * @code
355  * int range_index, component_index;
356  * AVOptionRanges *ranges;
357  * AVOptionRange *range[3]; //may require more than 3 in the future.
358  * av_opt_query_ranges(&ranges, obj, key, AV_OPT_MULTI_COMPONENT_RANGE);
359  * for (range_index = 0; range_index < ranges->nb_ranges; range_index++) {
360  * for (component_index = 0; component_index < ranges->nb_components; component_index++)
361  * range[component_index] = ranges->range[ranges->nb_ranges * component_index + range_index];
362  * //do something with range here.
363  * }
364  * av_opt_freep_ranges(&ranges);
365  * @endcode
366  */
368  /**
369  * Number of ranges per component.
370  */
372  /**
373  * Number of componentes.
374  */
377 
378 /**
379  * Show the obj options.
380  *
381  * @param req_flags requested flags for the options to show. Show only the
382  * options for which it is opt->flags & req_flags.
383  * @param rej_flags rejected flags for the options to show. Show only the
384  * options for which it is !(opt->flags & req_flags).
385  * @param av_log_obj log context to use for showing the options
386  */
387 int av_opt_show2(void *obj, void *av_log_obj, int req_flags, int rej_flags);
388 
389 /**
390  * Set the values of all AVOption fields to their default values.
391  *
392  * @param s an AVOption-enabled struct (its first member must be a pointer to AVClass)
393  */
394 void av_opt_set_defaults(void *s);
395 
396 /**
397  * Set the values of all AVOption fields to their default values. Only these
398  * AVOption fields for which (opt->flags & mask) == flags will have their
399  * default applied to s.
400  *
401  * @param s an AVOption-enabled struct (its first member must be a pointer to AVClass)
402  * @param mask combination of AV_OPT_FLAG_*
403  * @param flags combination of AV_OPT_FLAG_*
404  */
405 void av_opt_set_defaults2(void *s, int mask, int flags);
406 
407 /**
408  * Parse the key/value pairs list in opts. For each key/value pair
409  * found, stores the value in the field in ctx that is named like the
410  * key. ctx must be an AVClass context, storing is done using
411  * AVOptions.
412  *
413  * @param opts options string to parse, may be NULL
414  * @param key_val_sep a 0-terminated list of characters used to
415  * separate key from value
416  * @param pairs_sep a 0-terminated list of characters used to separate
417  * two pairs from each other
418  * @return the number of successfully set key/value pairs, or a negative
419  * value corresponding to an AVERROR code in case of error:
420  * AVERROR(EINVAL) if opts cannot be parsed,
421  * the error code issued by av_opt_set() if a key/value pair
422  * cannot be set
423  */
424 int av_set_options_string(void *ctx, const char *opts,
425  const char *key_val_sep, const char *pairs_sep);
426 
427 /**
428  * Parse the key-value pairs list in opts. For each key=value pair found,
429  * set the value of the corresponding option in ctx.
430  *
431  * @param ctx the AVClass object to set options on
432  * @param opts the options string, key-value pairs separated by a
433  * delimiter
434  * @param shorthand a NULL-terminated array of options names for shorthand
435  * notation: if the first field in opts has no key part,
436  * the key is taken from the first element of shorthand;
437  * then again for the second, etc., until either opts is
438  * finished, shorthand is finished or a named option is
439  * found; after that, all options must be named
440  * @param key_val_sep a 0-terminated list of characters used to separate
441  * key from value, for example '='
442  * @param pairs_sep a 0-terminated list of characters used to separate
443  * two pairs from each other, for example ':' or ','
444  * @return the number of successfully set key=value pairs, or a negative
445  * value corresponding to an AVERROR code in case of error:
446  * AVERROR(EINVAL) if opts cannot be parsed,
447  * the error code issued by av_set_string3() if a key/value pair
448  * cannot be set
449  *
450  * Options names must use only the following characters: a-z A-Z 0-9 - . / _
451  * Separators must use characters distinct from option names and from each
452  * other.
453  */
454 int av_opt_set_from_string(void *ctx, const char *opts,
455  const char *const *shorthand,
456  const char *key_val_sep, const char *pairs_sep);
457 /**
458  * Free all allocated objects in obj.
459  */
460 void av_opt_free(void *obj);
461 
462 /**
463  * Check whether a particular flag is set in a flags field.
464  *
465  * @param field_name the name of the flag field option
466  * @param flag_name the name of the flag to check
467  * @return non-zero if the flag is set, zero if the flag isn't set,
468  * isn't of the right type, or the flags field doesn't exist.
469  */
470 int av_opt_flag_is_set(void *obj, const char *field_name, const char *flag_name);
471 
472 /**
473  * Set all the options from a given dictionary on an object.
474  *
475  * @param obj a struct whose first element is a pointer to AVClass
476  * @param options options to process. This dictionary will be freed and replaced
477  * by a new one containing all options not found in obj.
478  * Of course this new dictionary needs to be freed by caller
479  * with av_dict_free().
480  *
481  * @return 0 on success, a negative AVERROR if some option was found in obj,
482  * but could not be set.
483  *
484  * @see av_dict_copy()
485  */
486 int av_opt_set_dict(void *obj, struct AVDictionary **options);
487 
488 
489 /**
490  * Set all the options from a given dictionary on an object.
491  *
492  * @param obj a struct whose first element is a pointer to AVClass
493  * @param options options to process. This dictionary will be freed and replaced
494  * by a new one containing all options not found in obj.
495  * Of course this new dictionary needs to be freed by caller
496  * with av_dict_free().
497  * @param search_flags A combination of AV_OPT_SEARCH_*.
498  *
499  * @return 0 on success, a negative AVERROR if some option was found in obj,
500  * but could not be set.
501  *
502  * @see av_dict_copy()
503  */
504 int av_opt_set_dict2(void *obj, struct AVDictionary **options, int search_flags);
505 
506 /**
507  * Extract a key-value pair from the beginning of a string.
508  *
509  * @param ropts pointer to the options string, will be updated to
510  * point to the rest of the string (one of the pairs_sep
511  * or the final NUL)
512  * @param key_val_sep a 0-terminated list of characters used to separate
513  * key from value, for example '='
514  * @param pairs_sep a 0-terminated list of characters used to separate
515  * two pairs from each other, for example ':' or ','
516  * @param flags flags; see the AV_OPT_FLAG_* values below
517  * @param rkey parsed key; must be freed using av_free()
518  * @param rval parsed value; must be freed using av_free()
519  *
520  * @return >=0 for success, or a negative value corresponding to an
521  * AVERROR code in case of error; in particular:
522  * AVERROR(EINVAL) if no key is present
523  *
524  */
525 int av_opt_get_key_value(const char **ropts,
526  const char *key_val_sep, const char *pairs_sep,
527  unsigned flags,
528  char **rkey, char **rval);
529 
530 enum {
531 
532  /**
533  * Accept to parse a value without a key; the key will then be returned
534  * as NULL.
535  */
537 };
538 
539 /**
540  * @defgroup opt_eval_funcs Evaluating option strings
541  * @{
542  * This group of functions can be used to evaluate option strings
543  * and get numbers out of them. They do the same thing as av_opt_set(),
544  * except the result is written into the caller-supplied pointer.
545  *
546  * @param obj a struct whose first element is a pointer to AVClass.
547  * @param o an option for which the string is to be evaluated.
548  * @param val string to be evaluated.
549  * @param *_out value of the string will be written here.
550  *
551  * @return 0 on success, a negative number on failure.
552  */
553 int av_opt_eval_flags (void *obj, const AVOption *o, const char *val, int *flags_out);
554 int av_opt_eval_int (void *obj, const AVOption *o, const char *val, int *int_out);
555 int av_opt_eval_int64 (void *obj, const AVOption *o, const char *val, int64_t *int64_out);
556 int av_opt_eval_float (void *obj, const AVOption *o, const char *val, float *float_out);
557 int av_opt_eval_double(void *obj, const AVOption *o, const char *val, double *double_out);
558 int av_opt_eval_q (void *obj, const AVOption *o, const char *val, AVRational *q_out);
559 /**
560  * @}
561  */
562 
563 #define AV_OPT_SEARCH_CHILDREN (1 << 0) /**< Search in possible children of the
564  given object first. */
565 /**
566  * The obj passed to av_opt_find() is fake -- only a double pointer to AVClass
567  * instead of a required pointer to a struct containing AVClass. This is
568  * useful for searching for options without needing to allocate the corresponding
569  * object.
570  */
571 #define AV_OPT_SEARCH_FAKE_OBJ (1 << 1)
572 
573 /**
574  * In av_opt_get, return NULL if the option has a pointer type and is set to NULL,
575  * rather than returning an empty string.
576  */
577 #define AV_OPT_ALLOW_NULL (1 << 2)
578 
579 /**
580  * Allows av_opt_query_ranges and av_opt_query_ranges_default to return more than
581  * one component for certain option types.
582  * @see AVOptionRanges for details.
583  */
584 #define AV_OPT_MULTI_COMPONENT_RANGE (1 << 12)
585 
586 /**
587  * Look for an option in an object. Consider only options which
588  * have all the specified flags set.
589  *
590  * @param[in] obj A pointer to a struct whose first element is a
591  * pointer to an AVClass.
592  * Alternatively a double pointer to an AVClass, if
593  * AV_OPT_SEARCH_FAKE_OBJ search flag is set.
594  * @param[in] name The name of the option to look for.
595  * @param[in] unit When searching for named constants, name of the unit
596  * it belongs to.
597  * @param opt_flags Find only options with all the specified flags set (AV_OPT_FLAG).
598  * @param search_flags A combination of AV_OPT_SEARCH_*.
599  *
600  * @return A pointer to the option found, or NULL if no option
601  * was found.
602  *
603  * @note Options found with AV_OPT_SEARCH_CHILDREN flag may not be settable
604  * directly with av_opt_set(). Use special calls which take an options
605  * AVDictionary (e.g. avformat_open_input()) to set options found with this
606  * flag.
607  */
608 const AVOption *av_opt_find(void *obj, const char *name, const char *unit,
609  int opt_flags, int search_flags);
610 
611 /**
612  * Look for an option in an object. Consider only options which
613  * have all the specified flags set.
614  *
615  * @param[in] obj A pointer to a struct whose first element is a
616  * pointer to an AVClass.
617  * Alternatively a double pointer to an AVClass, if
618  * AV_OPT_SEARCH_FAKE_OBJ search flag is set.
619  * @param[in] name The name of the option to look for.
620  * @param[in] unit When searching for named constants, name of the unit
621  * it belongs to.
622  * @param opt_flags Find only options with all the specified flags set (AV_OPT_FLAG).
623  * @param search_flags A combination of AV_OPT_SEARCH_*.
624  * @param[out] target_obj if non-NULL, an object to which the option belongs will be
625  * written here. It may be different from obj if AV_OPT_SEARCH_CHILDREN is present
626  * in search_flags. This parameter is ignored if search_flags contain
627  * AV_OPT_SEARCH_FAKE_OBJ.
628  *
629  * @return A pointer to the option found, or NULL if no option
630  * was found.
631  */
632 const AVOption *av_opt_find2(void *obj, const char *name, const char *unit,
633  int opt_flags, int search_flags, void **target_obj);
634 
635 /**
636  * Iterate over all AVOptions belonging to obj.
637  *
638  * @param obj an AVOptions-enabled struct or a double pointer to an
639  * AVClass describing it.
640  * @param prev result of the previous call to av_opt_next() on this object
641  * or NULL
642  * @return next AVOption or NULL
643  */
644 const AVOption *av_opt_next(const void *obj, const AVOption *prev);
645 
646 /**
647  * Iterate over AVOptions-enabled children of obj.
648  *
649  * @param prev result of a previous call to this function or NULL
650  * @return next AVOptions-enabled child or NULL
651  */
652 void *av_opt_child_next(void *obj, void *prev);
653 
654 /**
655  * Iterate over potential AVOptions-enabled children of parent.
656  *
657  * @param iter a pointer where iteration state is stored.
658  * @return AVClass corresponding to next potential child or NULL
659  */
660 const AVClass *av_opt_child_class_iterate(const AVClass *parent, void **iter);
661 
662 /**
663  * @defgroup opt_set_funcs Option setting functions
664  * @{
665  * Those functions set the field of obj with the given name to value.
666  *
667  * @param[in] obj A struct whose first element is a pointer to an AVClass.
668  * @param[in] name the name of the field to set
669  * @param[in] val The value to set. In case of av_opt_set() if the field is not
670  * of a string type, then the given string is parsed.
671  * SI postfixes and some named scalars are supported.
672  * If the field is of a numeric type, it has to be a numeric or named
673  * scalar. Behavior with more than one scalar and +- infix operators
674  * is undefined.
675  * If the field is of a flags type, it has to be a sequence of numeric
676  * scalars or named flags separated by '+' or '-'. Prefixing a flag
677  * with '+' causes it to be set without affecting the other flags;
678  * similarly, '-' unsets a flag.
679  * If the field is of a dictionary type, it has to be a ':' separated list of
680  * key=value parameters. Values containing ':' special characters must be
681  * escaped.
682  * @param search_flags flags passed to av_opt_find2. I.e. if AV_OPT_SEARCH_CHILDREN
683  * is passed here, then the option may be set on a child of obj.
684  *
685  * @return 0 if the value has been set, or an AVERROR code in case of
686  * error:
687  * AVERROR_OPTION_NOT_FOUND if no matching option exists
688  * AVERROR(ERANGE) if the value is out of range
689  * AVERROR(EINVAL) if the value is not valid
690  */
691 int av_opt_set (void *obj, const char *name, const char *val, int search_flags);
692 int av_opt_set_int (void *obj, const char *name, int64_t val, int search_flags);
693 int av_opt_set_double (void *obj, const char *name, double val, int search_flags);
694 int av_opt_set_q (void *obj, const char *name, AVRational val, int search_flags);
695 int av_opt_set_bin (void *obj, const char *name, const uint8_t *val, int size, int search_flags);
696 int av_opt_set_image_size(void *obj, const char *name, int w, int h, int search_flags);
697 int av_opt_set_pixel_fmt (void *obj, const char *name, enum AVPixelFormat fmt, int search_flags);
698 int av_opt_set_sample_fmt(void *obj, const char *name, enum AVSampleFormat fmt, int search_flags);
699 int av_opt_set_video_rate(void *obj, const char *name, AVRational val, int search_flags);
700 #if FF_API_OLD_CHANNEL_LAYOUT
702 int av_opt_set_channel_layout(void *obj, const char *name, int64_t ch_layout, int search_flags);
703 #endif
704 int av_opt_set_chlayout(void *obj, const char *name, const AVChannelLayout *layout, int search_flags);
705 /**
706  * @note Any old dictionary present is discarded and replaced with a copy of the new one. The
707  * caller still owns val is and responsible for freeing it.
708  */
709 int av_opt_set_dict_val(void *obj, const char *name, const AVDictionary *val, int search_flags);
710 
711 /**
712  * Set a binary option to an integer list.
713  *
714  * @param obj AVClass object to set options on
715  * @param name name of the binary option
716  * @param val pointer to an integer list (must have the correct type with
717  * regard to the contents of the list)
718  * @param term list terminator (usually 0 or -1)
719  * @param flags search flags
720  */
721 #define av_opt_set_int_list(obj, name, val, term, flags) \
722  (av_int_list_length(val, term) > INT_MAX / sizeof(*(val)) ? \
723  AVERROR(EINVAL) : \
724  av_opt_set_bin(obj, name, (const uint8_t *)(val), \
725  av_int_list_length(val, term) * sizeof(*(val)), flags))
726 
727 /**
728  * @}
729  */
730 
731 /**
732  * @defgroup opt_get_funcs Option getting functions
733  * @{
734  * Those functions get a value of the option with the given name from an object.
735  *
736  * @param[in] obj a struct whose first element is a pointer to an AVClass.
737  * @param[in] name name of the option to get.
738  * @param[in] search_flags flags passed to av_opt_find2. I.e. if AV_OPT_SEARCH_CHILDREN
739  * is passed here, then the option may be found in a child of obj.
740  * @param[out] out_val value of the option will be written here
741  * @return >=0 on success, a negative error code otherwise
742  */
743 /**
744  * @note the returned string will be av_malloc()ed and must be av_free()ed by the caller
745  *
746  * @note if AV_OPT_ALLOW_NULL is set in search_flags in av_opt_get, and the
747  * option is of type AV_OPT_TYPE_STRING, AV_OPT_TYPE_BINARY or AV_OPT_TYPE_DICT
748  * and is set to NULL, *out_val will be set to NULL instead of an allocated
749  * empty string.
750  */
751 int av_opt_get (void *obj, const char *name, int search_flags, uint8_t **out_val);
752 int av_opt_get_int (void *obj, const char *name, int search_flags, int64_t *out_val);
753 int av_opt_get_double (void *obj, const char *name, int search_flags, double *out_val);
754 int av_opt_get_q (void *obj, const char *name, int search_flags, AVRational *out_val);
755 int av_opt_get_image_size(void *obj, const char *name, int search_flags, int *w_out, int *h_out);
756 int av_opt_get_pixel_fmt (void *obj, const char *name, int search_flags, enum AVPixelFormat *out_fmt);
757 int av_opt_get_sample_fmt(void *obj, const char *name, int search_flags, enum AVSampleFormat *out_fmt);
758 int av_opt_get_video_rate(void *obj, const char *name, int search_flags, AVRational *out_val);
759 #if FF_API_OLD_CHANNEL_LAYOUT
761 int av_opt_get_channel_layout(void *obj, const char *name, int search_flags, int64_t *ch_layout);
762 #endif
763 int av_opt_get_chlayout(void *obj, const char *name, int search_flags, AVChannelLayout *layout);
764 /**
765  * @param[out] out_val The returned dictionary is a copy of the actual value and must
766  * be freed with av_dict_free() by the caller
767  */
768 int av_opt_get_dict_val(void *obj, const char *name, int search_flags, AVDictionary **out_val);
769 /**
770  * @}
771  */
772 /**
773  * Gets a pointer to the requested field in a struct.
774  * This function allows accessing a struct even when its fields are moved or
775  * renamed since the application making the access has been compiled,
776  *
777  * @returns a pointer to the field, it can be cast to the correct type and read
778  * or written to.
779  */
780 void *av_opt_ptr(const AVClass *avclass, void *obj, const char *name);
781 
782 /**
783  * Free an AVOptionRanges struct and set it to NULL.
784  */
786 
787 /**
788  * Get a list of allowed ranges for the given option.
789  *
790  * The returned list may depend on other fields in obj like for example profile.
791  *
792  * @param flags is a bitmask of flags, undefined flags should not be set and should be ignored
793  * AV_OPT_SEARCH_FAKE_OBJ indicates that the obj is a double pointer to a AVClass instead of a full instance
794  * AV_OPT_MULTI_COMPONENT_RANGE indicates that function may return more than one component, @see AVOptionRanges
795  *
796  * The result must be freed with av_opt_freep_ranges.
797  *
798  * @return number of compontents returned on success, a negative errro code otherwise
799  */
800 int av_opt_query_ranges(AVOptionRanges **, void *obj, const char *key, int flags);
801 
802 /**
803  * Copy options from src object into dest object.
804  *
805  * The underlying AVClass of both src and dest must coincide. The guarantee
806  * below does not apply if this is not fulfilled.
807  *
808  * Options that require memory allocation (e.g. string or binary) are malloc'ed in dest object.
809  * Original memory allocated for such options is freed unless both src and dest options points to the same memory.
810  *
811  * Even on error it is guaranteed that allocated options from src and dest
812  * no longer alias each other afterwards; in particular calling av_opt_free()
813  * on both src and dest is safe afterwards if dest has been memdup'ed from src.
814  *
815  * @param dest Object to copy from
816  * @param src Object to copy into
817  * @return 0 on success, negative on error
818  */
819 int av_opt_copy(void *dest, const void *src);
820 
821 /**
822  * Get a default list of allowed ranges for the given option.
823  *
824  * This list is constructed without using the AVClass.query_ranges() callback
825  * and can be used as fallback from within the callback.
826  *
827  * @param flags is a bitmask of flags, undefined flags should not be set and should be ignored
828  * AV_OPT_SEARCH_FAKE_OBJ indicates that the obj is a double pointer to a AVClass instead of a full instance
829  * AV_OPT_MULTI_COMPONENT_RANGE indicates that function may return more than one component, @see AVOptionRanges
830  *
831  * The result must be freed with av_opt_free_ranges.
832  *
833  * @return number of compontents returned on success, a negative errro code otherwise
834  */
835 int av_opt_query_ranges_default(AVOptionRanges **, void *obj, const char *key, int flags);
836 
837 /**
838  * Check if given option is set to its default value.
839  *
840  * Options o must belong to the obj. This function must not be called to check child's options state.
841  * @see av_opt_is_set_to_default_by_name().
842  *
843  * @param obj AVClass object to check option on
844  * @param o option to be checked
845  * @return >0 when option is set to its default,
846  * 0 when option is not set its default,
847  * <0 on error
848  */
849 int av_opt_is_set_to_default(void *obj, const AVOption *o);
850 
851 /**
852  * Check if given option is set to its default value.
853  *
854  * @param obj AVClass object to check option on
855  * @param name option name
856  * @param search_flags combination of AV_OPT_SEARCH_*
857  * @return >0 when option is set to its default,
858  * 0 when option is not set its default,
859  * <0 on error
860  */
861 int av_opt_is_set_to_default_by_name(void *obj, const char *name, int search_flags);
862 
863 
864 #define AV_OPT_SERIALIZE_SKIP_DEFAULTS 0x00000001 ///< Serialize options that are not set to default values only.
865 #define AV_OPT_SERIALIZE_OPT_FLAGS_EXACT 0x00000002 ///< Serialize options that exactly match opt_flags only.
866 
867 /**
868  * Serialize object's options.
869  *
870  * Create a string containing object's serialized options.
871  * Such string may be passed back to av_opt_set_from_string() in order to restore option values.
872  * A key/value or pairs separator occurring in the serialized value or
873  * name string are escaped through the av_escape() function.
874  *
875  * @param[in] obj AVClass object to serialize
876  * @param[in] opt_flags serialize options with all the specified flags set (AV_OPT_FLAG)
877  * @param[in] flags combination of AV_OPT_SERIALIZE_* flags
878  * @param[out] buffer Pointer to buffer that will be allocated with string containg serialized options.
879  * Buffer must be freed by the caller when is no longer needed.
880  * @param[in] key_val_sep character used to separate key from value
881  * @param[in] pairs_sep character used to separate two pairs from each other
882  * @return >= 0 on success, negative on error
883  * @warning Separators cannot be neither '\\' nor '\0'. They also cannot be the same.
884  */
885 int av_opt_serialize(void *obj, int opt_flags, int flags, char **buffer,
886  const char key_val_sep, const char pairs_sep);
887 /**
888  * @}
889  */
890 
891 #endif /* AVUTIL_OPT_H */
#define attribute_deprecated
Definition: attributes.h:100
Convenience header that includes libavutil's core.
Public libavutil channel layout APIs header.
Public dictionary API.
int av_opt_copy(void *dest, const void *src)
Copy options from src object into dest object.
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.
int av_opt_set_dict2(void *obj, struct AVDictionary **options, int search_flags)
Set all the options from a given dictionary on an object.
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.
int av_opt_is_set_to_default(void *obj, const AVOption *o)
Check if given option is set to its default value.
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.
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.
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.
void av_opt_freep_ranges(AVOptionRanges **ranges)
Free an AVOptionRanges struct and set it to NULL.
int av_opt_query_ranges(AVOptionRanges **, void *obj, const char *key, int flags)
Get a list of allowed ranges for the given option.
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.
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.
void * av_opt_child_next(void *obj, void *prev)
Iterate over AVOptions-enabled children of obj.
void * av_opt_ptr(const AVClass *avclass, void *obj, const char *name)
Gets a pointer to the requested field in a struct.
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.
const AVOption * av_opt_next(const void *obj, const AVOption *prev)
Iterate over all AVOptions belonging to obj.
AVOptionType
Definition: opt.h:223
void av_opt_free(void *obj)
Free all allocated objects in obj.
void av_opt_set_defaults(void *s)
Set the values of all AVOption fields to their default values.
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.
const AVClass * av_opt_child_class_iterate(const AVClass *parent, void **iter)
Iterate over potential AVOptions-enabled children of parent.
void av_opt_set_defaults2(void *s, int mask, int flags)
Set the values of all AVOption fields to their default values.
int av_opt_set_dict(void *obj, struct AVDictionary **options)
Set all the options from a given dictionary on an object.
int av_opt_show2(void *obj, void *av_log_obj, int req_flags, int rej_flags)
Show the obj options.
@ AV_OPT_FLAG_IMPLICIT_KEY
Accept to parse a value without a key; the key will then be returned as NULL.
Definition: opt.h:536
@ AV_OPT_TYPE_IMAGE_SIZE
offset must point to two consecutive integers
Definition: opt.h:235
@ AV_OPT_TYPE_CONST
Definition: opt.h:234
@ AV_OPT_TYPE_PIXEL_FMT
Definition: opt.h:236
@ AV_OPT_TYPE_BINARY
offset must point to a pointer immediately followed by an int for the length
Definition: opt.h:231
@ AV_OPT_TYPE_DURATION
Definition: opt.h:239
@ AV_OPT_TYPE_CHANNEL_LAYOUT
Definition: opt.h:242
@ AV_OPT_TYPE_SAMPLE_FMT
Definition: opt.h:237
@ AV_OPT_TYPE_RATIONAL
Definition: opt.h:230
@ AV_OPT_TYPE_FLAGS
Definition: opt.h:224
@ AV_OPT_TYPE_VIDEO_RATE
offset must point to AVRational
Definition: opt.h:238
@ AV_OPT_TYPE_INT64
Definition: opt.h:226
@ AV_OPT_TYPE_UINT64
Definition: opt.h:233
@ AV_OPT_TYPE_INT
Definition: opt.h:225
@ AV_OPT_TYPE_CHLAYOUT
Definition: opt.h:245
@ AV_OPT_TYPE_DOUBLE
Definition: opt.h:227
@ AV_OPT_TYPE_FLOAT
Definition: opt.h:228
@ AV_OPT_TYPE_DICT
Definition: opt.h:232
@ AV_OPT_TYPE_BOOL
Definition: opt.h:244
@ AV_OPT_TYPE_STRING
Definition: opt.h:229
@ AV_OPT_TYPE_COLOR
Definition: opt.h:240
unsigned size
allocated memory
Definition: bprint.h:99
struct AVDictionary AVDictionary
Definition: dict.h:94
AVSampleFormat
Audio sample formats.
Definition: samplefmt.h:55
int av_opt_eval_float(void *obj, const AVOption *o, const char *val, float *float_out)
int av_opt_eval_int(void *obj, const AVOption *o, const char *val, int *int_out)
int av_opt_eval_q(void *obj, const AVOption *o, const char *val, AVRational *q_out)
int av_opt_eval_double(void *obj, const AVOption *o, const char *val, double *double_out)
int av_opt_eval_int64(void *obj, const AVOption *o, const char *val, int64_t *int64_out)
int av_opt_eval_flags(void *obj, const AVOption *o, const char *val, int *flags_out)
int av_opt_get_pixel_fmt(void *obj, const char *name, int search_flags, enum AVPixelFormat *out_fmt)
int av_opt_get_double(void *obj, const char *name, int search_flags, double *out_val)
int av_opt_get_chlayout(void *obj, const char *name, int search_flags, AVChannelLayout *layout)
int av_opt_get_dict_val(void *obj, const char *name, int search_flags, AVDictionary **out_val)
int av_opt_get_image_size(void *obj, const char *name, int search_flags, int *w_out, int *h_out)
attribute_deprecated int av_opt_get_channel_layout(void *obj, const char *name, int search_flags, int64_t *ch_layout)
int av_opt_get_int(void *obj, const char *name, int search_flags, int64_t *out_val)
int av_opt_get_q(void *obj, const char *name, int search_flags, AVRational *out_val)
int av_opt_get_sample_fmt(void *obj, const char *name, int search_flags, enum AVSampleFormat *out_fmt)
int av_opt_get(void *obj, const char *name, int search_flags, uint8_t **out_val)
int av_opt_get_video_rate(void *obj, const char *name, int search_flags, AVRational *out_val)
int av_opt_set_double(void *obj, const char *name, double val, int search_flags)
int av_opt_set_image_size(void *obj, const char *name, int w, int h, int search_flags)
int av_opt_set_int(void *obj, const char *name, int64_t val, int search_flags)
int av_opt_set_q(void *obj, const char *name, AVRational val, int search_flags)
int av_opt_set(void *obj, const char *name, const char *val, int search_flags)
int av_opt_set_bin(void *obj, const char *name, const uint8_t *val, int size, int search_flags)
attribute_deprecated int av_opt_set_channel_layout(void *obj, const char *name, int64_t ch_layout, int search_flags)
int av_opt_set_chlayout(void *obj, const char *name, const AVChannelLayout *layout, int search_flags)
int av_opt_set_video_rate(void *obj, const char *name, AVRational val, int search_flags)
int av_opt_set_dict_val(void *obj, const char *name, const AVDictionary *val, int search_flags)
int av_opt_set_sample_fmt(void *obj, const char *name, enum AVSampleFormat fmt, int search_flags)
int av_opt_set_pixel_fmt(void *obj, const char *name, enum AVPixelFormat fmt, int search_flags)
pixel format definitions
AVPixelFormat
Pixel format.
Definition: pixfmt.h:64
Utilties for rational number calculation.
An AVChannelLayout holds information about the channel layout of audio data.
Describe the class of an AVClass context structure.
Definition: log.h:66
A single allowed range of values, or a single allowed value.
Definition: opt.h:313
double component_max
Definition: opt.h:325
double component_min
Value's component range.
Definition: opt.h:325
const char * str
Definition: opt.h:314
double value_max
Definition: opt.h:320
double value_min
Value range.
Definition: opt.h:320
int is_range
Range flag.
Definition: opt.h:330
List of AVOptionRange structs.
Definition: opt.h:336
int nb_ranges
Number of ranges per component.
Definition: opt.h:371
AVOptionRange ** range
Array of option ranges.
Definition: opt.h:367
int nb_components
Number of componentes.
Definition: opt.h:375
AVOption.
Definition: opt.h:251
double max
maximum valid value for the option
Definition: opt.h:278
int offset
The offset relative to the context structure where the option value is stored.
Definition: opt.h:264
const char * unit
The logical unit to which the option belongs.
Definition: opt.h:307
AVRational q
Definition: opt.h:275
const char * str
Definition: opt.h:273
const char * help
short English help text
Definition: opt.h:258
const char * name
Definition: opt.h:252
int64_t i64
Definition: opt.h:271
union AVOption::@11 default_val
the default value for scalar options
double min
minimum valid value for the option
Definition: opt.h:277
int flags
Definition: opt.h:280
enum AVOptionType type
Definition: opt.h:265
double dbl
Definition: opt.h:272
Rational number (pair of numerator and denominator).
Definition: rational.h:58