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 "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_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
243 };
244 
245 /**
246  * AVOption
247  */
248 typedef struct AVOption {
249  const char *name;
250 
251  /**
252  * short English help text
253  * @todo What about other languages?
254  */
255  const char *help;
256 
257  /**
258  * The offset relative to the context structure where the option
259  * value is stored. It should be 0 for named constants.
260  */
261  int offset;
263 
264  /**
265  * the default value for scalar options
266  */
267  union {
268  int64_t i64;
269  double dbl;
270  const char *str;
271  /* TODO those are unused now */
273  } default_val;
274  double min; ///< minimum valid value for the option
275  double max; ///< maximum valid value for the option
276 
277  int flags;
278 #define AV_OPT_FLAG_ENCODING_PARAM 1 ///< a generic parameter which can be set by the user for muxing or encoding
279 #define AV_OPT_FLAG_DECODING_PARAM 2 ///< a generic parameter which can be set by the user for demuxing or decoding
280 #define AV_OPT_FLAG_AUDIO_PARAM 8
281 #define AV_OPT_FLAG_VIDEO_PARAM 16
282 #define AV_OPT_FLAG_SUBTITLE_PARAM 32
283 /**
284  * The option is intended for exporting values to the caller.
285  */
286 #define AV_OPT_FLAG_EXPORT 64
287 /**
288  * The option may not be set through the AVOptions API, only read.
289  * This flag only makes sense when AV_OPT_FLAG_EXPORT is also set.
290  */
291 #define AV_OPT_FLAG_READONLY 128
292 #define AV_OPT_FLAG_BSF_PARAM (1<<8) ///< a generic parameter which can be set by the user for bit stream filtering
293 #define AV_OPT_FLAG_RUNTIME_PARAM (1<<15) ///< a generic parameter which can be set by the user at runtime
294 #define AV_OPT_FLAG_FILTERING_PARAM (1<<16) ///< a generic parameter which can be set by the user for filtering
295 #define AV_OPT_FLAG_DEPRECATED (1<<17) ///< set if option is deprecated, users should refer to AVOption.help text for more information
296 #define AV_OPT_FLAG_CHILD_CONSTS (1<<18) ///< set if option constants can also reside in child objects
297 //FIXME think about enc-audio, ... style flags
298 
299  /**
300  * The logical unit to which the option belongs. Non-constant
301  * options and corresponding named constants share the same
302  * unit. May be NULL.
303  */
304  const char *unit;
305 } AVOption;
306 
307 /**
308  * A single allowed range of values, or a single allowed value.
309  */
310 typedef struct AVOptionRange {
311  const char *str;
312  /**
313  * Value range.
314  * For string ranges this represents the min/max length.
315  * For dimensions this represents the min/max pixel count or width/height in multi-component case.
316  */
318  /**
319  * Value's component range.
320  * For string this represents the unicode range for chars, 0-127 limits to ASCII.
321  */
323  /**
324  * Range flag.
325  * If set to 1 the struct encodes a range, if set to 0 a single value.
326  */
327  int is_range;
328 } AVOptionRange;
329 
330 /**
331  * List of AVOptionRange structs.
332  */
333 typedef struct AVOptionRanges {
334  /**
335  * Array of option ranges.
336  *
337  * Most of option types use just one component.
338  * Following describes multi-component option types:
339  *
340  * AV_OPT_TYPE_IMAGE_SIZE:
341  * component index 0: range of pixel count (width * height).
342  * component index 1: range of width.
343  * component index 2: range of height.
344  *
345  * @note To obtain multi-component version of this structure, user must
346  * provide AV_OPT_MULTI_COMPONENT_RANGE to av_opt_query_ranges or
347  * av_opt_query_ranges_default function.
348  *
349  * Multi-component range can be read as in following example:
350  *
351  * @code
352  * int range_index, component_index;
353  * AVOptionRanges *ranges;
354  * AVOptionRange *range[3]; //may require more than 3 in the future.
355  * av_opt_query_ranges(&ranges, obj, key, AV_OPT_MULTI_COMPONENT_RANGE);
356  * for (range_index = 0; range_index < ranges->nb_ranges; range_index++) {
357  * for (component_index = 0; component_index < ranges->nb_components; component_index++)
358  * range[component_index] = ranges->range[ranges->nb_ranges * component_index + range_index];
359  * //do something with range here.
360  * }
361  * av_opt_freep_ranges(&ranges);
362  * @endcode
363  */
365  /**
366  * Number of ranges per component.
367  */
369  /**
370  * Number of componentes.
371  */
374 
375 /**
376  * Show the obj options.
377  *
378  * @param req_flags requested flags for the options to show. Show only the
379  * options for which it is opt->flags & req_flags.
380  * @param rej_flags rejected flags for the options to show. Show only the
381  * options for which it is !(opt->flags & req_flags).
382  * @param av_log_obj log context to use for showing the options
383  */
384 int av_opt_show2(void *obj, void *av_log_obj, int req_flags, int rej_flags);
385 
386 /**
387  * Set the values of all AVOption fields to their default values.
388  *
389  * @param s an AVOption-enabled struct (its first member must be a pointer to AVClass)
390  */
391 void av_opt_set_defaults(void *s);
392 
393 /**
394  * Set the values of all AVOption fields to their default values. Only these
395  * AVOption fields for which (opt->flags & mask) == flags will have their
396  * default applied to s.
397  *
398  * @param s an AVOption-enabled struct (its first member must be a pointer to AVClass)
399  * @param mask combination of AV_OPT_FLAG_*
400  * @param flags combination of AV_OPT_FLAG_*
401  */
402 void av_opt_set_defaults2(void *s, int mask, int flags);
403 
404 /**
405  * Parse the key/value pairs list in opts. For each key/value pair
406  * found, stores the value in the field in ctx that is named like the
407  * key. ctx must be an AVClass context, storing is done using
408  * AVOptions.
409  *
410  * @param opts options string to parse, may be NULL
411  * @param key_val_sep a 0-terminated list of characters used to
412  * separate key from value
413  * @param pairs_sep a 0-terminated list of characters used to separate
414  * two pairs from each other
415  * @return the number of successfully set key/value pairs, or a negative
416  * value corresponding to an AVERROR code in case of error:
417  * AVERROR(EINVAL) if opts cannot be parsed,
418  * the error code issued by av_opt_set() if a key/value pair
419  * cannot be set
420  */
421 int av_set_options_string(void *ctx, const char *opts,
422  const char *key_val_sep, const char *pairs_sep);
423 
424 /**
425  * Parse the key-value pairs list in opts. For each key=value pair found,
426  * set the value of the corresponding option in ctx.
427  *
428  * @param ctx the AVClass object to set options on
429  * @param opts the options string, key-value pairs separated by a
430  * delimiter
431  * @param shorthand a NULL-terminated array of options names for shorthand
432  * notation: if the first field in opts has no key part,
433  * the key is taken from the first element of shorthand;
434  * then again for the second, etc., until either opts is
435  * finished, shorthand is finished or a named option is
436  * found; after that, all options must be named
437  * @param key_val_sep a 0-terminated list of characters used to separate
438  * key from value, for example '='
439  * @param pairs_sep a 0-terminated list of characters used to separate
440  * two pairs from each other, for example ':' or ','
441  * @return the number of successfully set key=value pairs, or a negative
442  * value corresponding to an AVERROR code in case of error:
443  * AVERROR(EINVAL) if opts cannot be parsed,
444  * the error code issued by av_set_string3() if a key/value pair
445  * cannot be set
446  *
447  * Options names must use only the following characters: a-z A-Z 0-9 - . / _
448  * Separators must use characters distinct from option names and from each
449  * other.
450  */
451 int av_opt_set_from_string(void *ctx, const char *opts,
452  const char *const *shorthand,
453  const char *key_val_sep, const char *pairs_sep);
454 /**
455  * Free all allocated objects in obj.
456  */
457 void av_opt_free(void *obj);
458 
459 /**
460  * Check whether a particular flag is set in a flags field.
461  *
462  * @param field_name the name of the flag field option
463  * @param flag_name the name of the flag to check
464  * @return non-zero if the flag is set, zero if the flag isn't set,
465  * isn't of the right type, or the flags field doesn't exist.
466  */
467 int av_opt_flag_is_set(void *obj, const char *field_name, const char *flag_name);
468 
469 /**
470  * Set all the options from a given dictionary on an object.
471  *
472  * @param obj a struct whose first element is a pointer to AVClass
473  * @param options options to process. This dictionary will be freed and replaced
474  * by a new one containing all options not found in obj.
475  * Of course this new dictionary needs to be freed by caller
476  * with av_dict_free().
477  *
478  * @return 0 on success, a negative AVERROR if some option was found in obj,
479  * but could not be set.
480  *
481  * @see av_dict_copy()
482  */
483 int av_opt_set_dict(void *obj, struct AVDictionary **options);
484 
485 
486 /**
487  * Set all the options from a given dictionary on an object.
488  *
489  * @param obj a struct whose first element is a pointer to AVClass
490  * @param options options to process. This dictionary will be freed and replaced
491  * by a new one containing all options not found in obj.
492  * Of course this new dictionary needs to be freed by caller
493  * with av_dict_free().
494  * @param search_flags A combination of AV_OPT_SEARCH_*.
495  *
496  * @return 0 on success, a negative AVERROR if some option was found in obj,
497  * but could not be set.
498  *
499  * @see av_dict_copy()
500  */
501 int av_opt_set_dict2(void *obj, struct AVDictionary **options, int search_flags);
502 
503 /**
504  * Extract a key-value pair from the beginning of a string.
505  *
506  * @param ropts pointer to the options string, will be updated to
507  * point to the rest of the string (one of the pairs_sep
508  * or the final NUL)
509  * @param key_val_sep a 0-terminated list of characters used to separate
510  * key from value, for example '='
511  * @param pairs_sep a 0-terminated list of characters used to separate
512  * two pairs from each other, for example ':' or ','
513  * @param flags flags; see the AV_OPT_FLAG_* values below
514  * @param rkey parsed key; must be freed using av_free()
515  * @param rval parsed value; must be freed using av_free()
516  *
517  * @return >=0 for success, or a negative value corresponding to an
518  * AVERROR code in case of error; in particular:
519  * AVERROR(EINVAL) if no key is present
520  *
521  */
522 int av_opt_get_key_value(const char **ropts,
523  const char *key_val_sep, const char *pairs_sep,
524  unsigned flags,
525  char **rkey, char **rval);
526 
527 enum {
528 
529  /**
530  * Accept to parse a value without a key; the key will then be returned
531  * as NULL.
532  */
534 };
535 
536 /**
537  * @defgroup opt_eval_funcs Evaluating option strings
538  * @{
539  * This group of functions can be used to evaluate option strings
540  * and get numbers out of them. They do the same thing as av_opt_set(),
541  * except the result is written into the caller-supplied pointer.
542  *
543  * @param obj a struct whose first element is a pointer to AVClass.
544  * @param o an option for which the string is to be evaluated.
545  * @param val string to be evaluated.
546  * @param *_out value of the string will be written here.
547  *
548  * @return 0 on success, a negative number on failure.
549  */
550 int av_opt_eval_flags (void *obj, const AVOption *o, const char *val, int *flags_out);
551 int av_opt_eval_int (void *obj, const AVOption *o, const char *val, int *int_out);
552 int av_opt_eval_int64 (void *obj, const AVOption *o, const char *val, int64_t *int64_out);
553 int av_opt_eval_float (void *obj, const AVOption *o, const char *val, float *float_out);
554 int av_opt_eval_double(void *obj, const AVOption *o, const char *val, double *double_out);
555 int av_opt_eval_q (void *obj, const AVOption *o, const char *val, AVRational *q_out);
556 /**
557  * @}
558  */
559 
560 #define AV_OPT_SEARCH_CHILDREN (1 << 0) /**< Search in possible children of the
561  given object first. */
562 /**
563  * The obj passed to av_opt_find() is fake -- only a double pointer to AVClass
564  * instead of a required pointer to a struct containing AVClass. This is
565  * useful for searching for options without needing to allocate the corresponding
566  * object.
567  */
568 #define AV_OPT_SEARCH_FAKE_OBJ (1 << 1)
569 
570 /**
571  * In av_opt_get, return NULL if the option has a pointer type and is set to NULL,
572  * rather than returning an empty string.
573  */
574 #define AV_OPT_ALLOW_NULL (1 << 2)
575 
576 /**
577  * Allows av_opt_query_ranges and av_opt_query_ranges_default to return more than
578  * one component for certain option types.
579  * @see AVOptionRanges for details.
580  */
581 #define AV_OPT_MULTI_COMPONENT_RANGE (1 << 12)
582 
583 /**
584  * Look for an option in an object. Consider only options which
585  * have all the specified flags set.
586  *
587  * @param[in] obj A pointer to a struct whose first element is a
588  * pointer to an AVClass.
589  * Alternatively a double pointer to an AVClass, if
590  * AV_OPT_SEARCH_FAKE_OBJ search flag is set.
591  * @param[in] name The name of the option to look for.
592  * @param[in] unit When searching for named constants, name of the unit
593  * it belongs to.
594  * @param opt_flags Find only options with all the specified flags set (AV_OPT_FLAG).
595  * @param search_flags A combination of AV_OPT_SEARCH_*.
596  *
597  * @return A pointer to the option found, or NULL if no option
598  * was found.
599  *
600  * @note Options found with AV_OPT_SEARCH_CHILDREN flag may not be settable
601  * directly with av_opt_set(). Use special calls which take an options
602  * AVDictionary (e.g. avformat_open_input()) to set options found with this
603  * flag.
604  */
605 const AVOption *av_opt_find(void *obj, const char *name, const char *unit,
606  int opt_flags, int search_flags);
607 
608 /**
609  * Look for an option in an object. Consider only options which
610  * have all the specified flags set.
611  *
612  * @param[in] obj A pointer to a struct whose first element is a
613  * pointer to an AVClass.
614  * Alternatively a double pointer to an AVClass, if
615  * AV_OPT_SEARCH_FAKE_OBJ search flag is set.
616  * @param[in] name The name of the option to look for.
617  * @param[in] unit When searching for named constants, name of the unit
618  * it belongs to.
619  * @param opt_flags Find only options with all the specified flags set (AV_OPT_FLAG).
620  * @param search_flags A combination of AV_OPT_SEARCH_*.
621  * @param[out] target_obj if non-NULL, an object to which the option belongs will be
622  * written here. It may be different from obj if AV_OPT_SEARCH_CHILDREN is present
623  * in search_flags. This parameter is ignored if search_flags contain
624  * AV_OPT_SEARCH_FAKE_OBJ.
625  *
626  * @return A pointer to the option found, or NULL if no option
627  * was found.
628  */
629 const AVOption *av_opt_find2(void *obj, const char *name, const char *unit,
630  int opt_flags, int search_flags, void **target_obj);
631 
632 /**
633  * Iterate over all AVOptions belonging to obj.
634  *
635  * @param obj an AVOptions-enabled struct or a double pointer to an
636  * AVClass describing it.
637  * @param prev result of the previous call to av_opt_next() on this object
638  * or NULL
639  * @return next AVOption or NULL
640  */
641 const AVOption *av_opt_next(const void *obj, const AVOption *prev);
642 
643 /**
644  * Iterate over AVOptions-enabled children of obj.
645  *
646  * @param prev result of a previous call to this function or NULL
647  * @return next AVOptions-enabled child or NULL
648  */
649 void *av_opt_child_next(void *obj, void *prev);
650 
651 /**
652  * Iterate over potential AVOptions-enabled children of parent.
653  *
654  * @param iter a pointer where iteration state is stored.
655  * @return AVClass corresponding to next potential child or NULL
656  */
657 const AVClass *av_opt_child_class_iterate(const AVClass *parent, void **iter);
658 
659 /**
660  * @defgroup opt_set_funcs Option setting functions
661  * @{
662  * Those functions set the field of obj with the given name to value.
663  *
664  * @param[in] obj A struct whose first element is a pointer to an AVClass.
665  * @param[in] name the name of the field to set
666  * @param[in] val The value to set. In case of av_opt_set() if the field is not
667  * of a string type, then the given string is parsed.
668  * SI postfixes and some named scalars are supported.
669  * If the field is of a numeric type, it has to be a numeric or named
670  * scalar. Behavior with more than one scalar and +- infix operators
671  * is undefined.
672  * If the field is of a flags type, it has to be a sequence of numeric
673  * scalars or named flags separated by '+' or '-'. Prefixing a flag
674  * with '+' causes it to be set without affecting the other flags;
675  * similarly, '-' unsets a flag.
676  * If the field is of a dictionary type, it has to be a ':' separated list of
677  * key=value parameters. Values containing ':' special characters must be
678  * escaped.
679  * @param search_flags flags passed to av_opt_find2. I.e. if AV_OPT_SEARCH_CHILDREN
680  * is passed here, then the option may be set on a child of obj.
681  *
682  * @return 0 if the value has been set, or an AVERROR code in case of
683  * error:
684  * AVERROR_OPTION_NOT_FOUND if no matching option exists
685  * AVERROR(ERANGE) if the value is out of range
686  * AVERROR(EINVAL) if the value is not valid
687  */
688 int av_opt_set (void *obj, const char *name, const char *val, int search_flags);
689 int av_opt_set_int (void *obj, const char *name, int64_t val, int search_flags);
690 int av_opt_set_double (void *obj, const char *name, double val, int search_flags);
691 int av_opt_set_q (void *obj, const char *name, AVRational val, int search_flags);
692 int av_opt_set_bin (void *obj, const char *name, const uint8_t *val, int size, int search_flags);
693 int av_opt_set_image_size(void *obj, const char *name, int w, int h, int search_flags);
694 int av_opt_set_pixel_fmt (void *obj, const char *name, enum AVPixelFormat fmt, int search_flags);
695 int av_opt_set_sample_fmt(void *obj, const char *name, enum AVSampleFormat fmt, int search_flags);
696 int av_opt_set_video_rate(void *obj, const char *name, AVRational val, int search_flags);
697 int av_opt_set_channel_layout(void *obj, const char *name, int64_t ch_layout, int search_flags);
698 /**
699  * @note Any old dictionary present is discarded and replaced with a copy of the new one. The
700  * caller still owns val is and responsible for freeing it.
701  */
702 int av_opt_set_dict_val(void *obj, const char *name, const AVDictionary *val, int search_flags);
703 
704 /**
705  * Set a binary option to an integer list.
706  *
707  * @param obj AVClass object to set options on
708  * @param name name of the binary option
709  * @param val pointer to an integer list (must have the correct type with
710  * regard to the contents of the list)
711  * @param term list terminator (usually 0 or -1)
712  * @param flags search flags
713  */
714 #define av_opt_set_int_list(obj, name, val, term, flags) \
715  (av_int_list_length(val, term) > INT_MAX / sizeof(*(val)) ? \
716  AVERROR(EINVAL) : \
717  av_opt_set_bin(obj, name, (const uint8_t *)(val), \
718  av_int_list_length(val, term) * sizeof(*(val)), flags))
719 
720 /**
721  * @}
722  */
723 
724 /**
725  * @defgroup opt_get_funcs Option getting functions
726  * @{
727  * Those functions get a value of the option with the given name from an object.
728  *
729  * @param[in] obj a struct whose first element is a pointer to an AVClass.
730  * @param[in] name name of the option to get.
731  * @param[in] search_flags flags passed to av_opt_find2. I.e. if AV_OPT_SEARCH_CHILDREN
732  * is passed here, then the option may be found in a child of obj.
733  * @param[out] out_val value of the option will be written here
734  * @return >=0 on success, a negative error code otherwise
735  */
736 /**
737  * @note the returned string will be av_malloc()ed and must be av_free()ed by the caller
738  *
739  * @note if AV_OPT_ALLOW_NULL is set in search_flags in av_opt_get, and the
740  * option is of type AV_OPT_TYPE_STRING, AV_OPT_TYPE_BINARY or AV_OPT_TYPE_DICT
741  * and is set to NULL, *out_val will be set to NULL instead of an allocated
742  * empty string.
743  */
744 int av_opt_get (void *obj, const char *name, int search_flags, uint8_t **out_val);
745 int av_opt_get_int (void *obj, const char *name, int search_flags, int64_t *out_val);
746 int av_opt_get_double (void *obj, const char *name, int search_flags, double *out_val);
747 int av_opt_get_q (void *obj, const char *name, int search_flags, AVRational *out_val);
748 int av_opt_get_image_size(void *obj, const char *name, int search_flags, int *w_out, int *h_out);
749 int av_opt_get_pixel_fmt (void *obj, const char *name, int search_flags, enum AVPixelFormat *out_fmt);
750 int av_opt_get_sample_fmt(void *obj, const char *name, int search_flags, enum AVSampleFormat *out_fmt);
751 int av_opt_get_video_rate(void *obj, const char *name, int search_flags, AVRational *out_val);
752 int av_opt_get_channel_layout(void *obj, const char *name, int search_flags, int64_t *ch_layout);
753 /**
754  * @param[out] out_val The returned dictionary is a copy of the actual value and must
755  * be freed with av_dict_free() by the caller
756  */
757 int av_opt_get_dict_val(void *obj, const char *name, int search_flags, AVDictionary **out_val);
758 /**
759  * @}
760  */
761 /**
762  * Gets a pointer to the requested field in a struct.
763  * This function allows accessing a struct even when its fields are moved or
764  * renamed since the application making the access has been compiled,
765  *
766  * @returns a pointer to the field, it can be cast to the correct type and read
767  * or written to.
768  */
769 void *av_opt_ptr(const AVClass *avclass, void *obj, const char *name);
770 
771 /**
772  * Free an AVOptionRanges struct and set it to NULL.
773  */
774 void av_opt_freep_ranges(AVOptionRanges **ranges);
775 
776 /**
777  * Get a list of allowed ranges for the given option.
778  *
779  * The returned list may depend on other fields in obj like for example profile.
780  *
781  * @param flags is a bitmask of flags, undefined flags should not be set and should be ignored
782  * AV_OPT_SEARCH_FAKE_OBJ indicates that the obj is a double pointer to a AVClass instead of a full instance
783  * AV_OPT_MULTI_COMPONENT_RANGE indicates that function may return more than one component, @see AVOptionRanges
784  *
785  * The result must be freed with av_opt_freep_ranges.
786  *
787  * @return number of compontents returned on success, a negative errro code otherwise
788  */
789 int av_opt_query_ranges(AVOptionRanges **, void *obj, const char *key, int flags);
790 
791 /**
792  * Copy options from src object into dest object.
793  *
794  * Options that require memory allocation (e.g. string or binary) are malloc'ed in dest object.
795  * Original memory allocated for such options is freed unless both src and dest options points to the same memory.
796  *
797  * @param dest Object to copy from
798  * @param src Object to copy into
799  * @return 0 on success, negative on error
800  */
801 int av_opt_copy(void *dest, const void *src);
802 
803 /**
804  * Get a default list of allowed ranges for the given option.
805  *
806  * This list is constructed without using the AVClass.query_ranges() callback
807  * and can be used as fallback from within the callback.
808  *
809  * @param flags is a bitmask of flags, undefined flags should not be set and should be ignored
810  * AV_OPT_SEARCH_FAKE_OBJ indicates that the obj is a double pointer to a AVClass instead of a full instance
811  * AV_OPT_MULTI_COMPONENT_RANGE indicates that function may return more than one component, @see AVOptionRanges
812  *
813  * The result must be freed with av_opt_free_ranges.
814  *
815  * @return number of compontents returned on success, a negative errro code otherwise
816  */
817 int av_opt_query_ranges_default(AVOptionRanges **, void *obj, const char *key, int flags);
818 
819 /**
820  * Check if given option is set to its default value.
821  *
822  * Options o must belong to the obj. This function must not be called to check child's options state.
823  * @see av_opt_is_set_to_default_by_name().
824  *
825  * @param obj AVClass object to check option on
826  * @param o option to be checked
827  * @return >0 when option is set to its default,
828  * 0 when option is not set its default,
829  * <0 on error
830  */
831 int av_opt_is_set_to_default(void *obj, const AVOption *o);
832 
833 /**
834  * Check if given option is set to its default value.
835  *
836  * @param obj AVClass object to check option on
837  * @param name option name
838  * @param search_flags combination of AV_OPT_SEARCH_*
839  * @return >0 when option is set to its default,
840  * 0 when option is not set its default,
841  * <0 on error
842  */
843 int av_opt_is_set_to_default_by_name(void *obj, const char *name, int search_flags);
844 
845 
846 #define AV_OPT_SERIALIZE_SKIP_DEFAULTS 0x00000001 ///< Serialize options that are not set to default values only.
847 #define AV_OPT_SERIALIZE_OPT_FLAGS_EXACT 0x00000002 ///< Serialize options that exactly match opt_flags only.
848 
849 /**
850  * Serialize object's options.
851  *
852  * Create a string containing object's serialized options.
853  * Such string may be passed back to av_opt_set_from_string() in order to restore option values.
854  * A key/value or pairs separator occurring in the serialized value or
855  * name string are escaped through the av_escape() function.
856  *
857  * @param[in] obj AVClass object to serialize
858  * @param[in] opt_flags serialize options with all the specified flags set (AV_OPT_FLAG)
859  * @param[in] flags combination of AV_OPT_SERIALIZE_* flags
860  * @param[out] buffer Pointer to buffer that will be allocated with string containg serialized options.
861  * Buffer must be freed by the caller when is no longer needed.
862  * @param[in] key_val_sep character used to separate key from value
863  * @param[in] pairs_sep character used to separate two pairs from each other
864  * @return >= 0 on success, negative on error
865  * @warning Separators cannot be neither '\\' nor '\0'. They also cannot be the same.
866  */
867 int av_opt_serialize(void *obj, int opt_flags, int flags, char **buffer,
868  const char key_val_sep, const char pairs_sep);
869 /**
870  * @}
871  */
872 
873 #endif /* AVUTIL_OPT_H */
AVOptionRange::is_range
int is_range
Range flag.
Definition: opt.h:327
av_opt_get_dict_val
int av_opt_get_dict_val(void *obj, const char *name, int search_flags, AVDictionary **out_val)
Definition: opt.c:1031
av_opt_set_image_size
int av_opt_set_image_size(void *obj, const char *name, int w, int h, int search_flags)
Definition: opt.c:631
AVOption::i64
int64_t i64
Definition: opt.h:268
AVPixelFormat
AVPixelFormat
Pixel format.
Definition: pixfmt.h:64
name
it s the only field you need to keep assuming you have a context There is some magic you don t need to care about around this just let it vf default minimum maximum flags name is the option name
Definition: writing_filters.txt:88
AVOptionRanges::nb_components
int nb_components
Number of componentes.
Definition: opt.h:372
AV_OPT_TYPE_SAMPLE_FMT
@ AV_OPT_TYPE_SAMPLE_FMT
Definition: opt.h:237
av_opt_set_defaults
void av_opt_set_defaults(void *s)
Set the values of all AVOption fields to their default values.
Definition: opt.c:1358
AVOptionRange::value_max
double value_max
Definition: opt.h:317
AVOptionType
AVOptionType
Definition: opt.h:223
av_opt_ptr
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:1727
AV_OPT_TYPE_VIDEO_RATE
@ AV_OPT_TYPE_VIDEO_RATE
offset must point to AVRational
Definition: opt.h:238
rational.h
AVOptionRange::value_min
double value_min
Value range.
Definition: opt.h:317
AVOptionRanges::nb_ranges
int nb_ranges
Number of ranges per component.
Definition: opt.h:368
w
uint8_t w
Definition: llviddspenc.c:39
av_opt_is_set_to_default_by_name
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:2051
av_opt_set_double
int av_opt_set_double(void *obj, const char *name, double val, int search_flags)
Definition: opt.c:591
AVOption
AVOption.
Definition: opt.h:248
AV_OPT_TYPE_DURATION
@ AV_OPT_TYPE_DURATION
Definition: opt.h:239
av_opt_is_set_to_default
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:1940
AVOption::help
const char * help
short English help text
Definition: opt.h:255
AVOption::flags
int flags
Definition: opt.h:277
AVDictionary
Definition: dict.c:30
AV_OPT_TYPE_RATIONAL
@ AV_OPT_TYPE_RATIONAL
Definition: opt.h:230
av_set_options_string
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:1479
AV_OPT_TYPE_BINARY
@ AV_OPT_TYPE_BINARY
offset must point to a pointer immediately followed by an int for the length
Definition: opt.h:231
AVOption::offset
int offset
The offset relative to the context structure where the option value is stored.
Definition: opt.h:261
samplefmt.h
val
static double val(void *priv, double ch)
Definition: aeval.c:76
av_opt_set
int av_opt_set(void *obj, const char *name, const char *val, int search_flags)
Definition: opt.c:465
av_opt_get_channel_layout
int av_opt_get_channel_layout(void *obj, const char *name, int search_flags, int64_t *ch_layout)
Definition: opt.c:1014
mask
static const uint16_t mask[17]
Definition: lzw.c:38
av_opt_set_dict
int av_opt_set_dict(void *obj, struct AVDictionary **options)
Set all the options from a given dictionary on an object.
Definition: opt.c:1656
s
#define s(width, name)
Definition: cbs_vp9.c:257
AV_OPT_TYPE_DOUBLE
@ AV_OPT_TYPE_DOUBLE
Definition: opt.h:227
AVOptionRange::str
const char * str
Definition: opt.h:311
av_opt_set_dict_val
int av_opt_set_dict_val(void *obj, const char *name, const AVDictionary *val, int search_flags)
Definition: opt.c:725
av_opt_set_pixel_fmt
int av_opt_set_pixel_fmt(void *obj, const char *name, enum AVPixelFormat fmt, int search_flags)
Definition: opt.c:699
AV_OPT_TYPE_INT64
@ AV_OPT_TYPE_INT64
Definition: opt.h:226
av_opt_eval_int64
int av_opt_eval_int64(void *obj, const AVOption *o, const char *val, int64_t *int64_out)
AV_OPT_FLAG_IMPLICIT_KEY
@ AV_OPT_FLAG_IMPLICIT_KEY
Accept to parse a value without a key; the key will then be returned as NULL.
Definition: opt.h:533
ctx
AVFormatContext * ctx
Definition: movenc.c:48
key
const char * key
Definition: hwcontext_opencl.c:168
av_opt_get_pixel_fmt
int av_opt_get_pixel_fmt(void *obj, const char *name, int search_flags, enum AVPixelFormat *out_fmt)
Definition: opt.c:1004
av_opt_find
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:1661
av_opt_get_video_rate
int av_opt_get_video_rate(void *obj, const char *name, int search_flags, AVRational *out_val)
Definition: opt.c:970
opts
AVDictionary * opts
Definition: movenc.c:50
AVClass
Describe the class of an AVClass context structure.
Definition: log.h:67
av_opt_set_video_rate
int av_opt_set_video_rate(void *obj, const char *name, AVRational val, int search_flags)
Definition: opt.c:653
av_opt_set_bin
int av_opt_set_bin(void *obj, const char *name, const uint8_t *val, int size, int search_flags)
Definition: opt.c:601
av_opt_get_double
int av_opt_get_double(void *obj, const char *name, int search_flags, double *out_val)
Definition: opt.c:924
AVRational
Rational number (pair of numerator and denominator).
Definition: rational.h:58
AV_OPT_TYPE_COLOR
@ AV_OPT_TYPE_COLOR
Definition: opt.h:240
av_opt_set_from_string
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:1559
AV_OPT_TYPE_IMAGE_SIZE
@ AV_OPT_TYPE_IMAGE_SIZE
offset must point to two consecutive integers
Definition: opt.h:235
AV_OPT_TYPE_DICT
@ AV_OPT_TYPE_DICT
Definition: opt.h:232
src
#define src
Definition: vp8dsp.c:255
AVOptionRange::component_min
double component_min
Value's component range.
Definition: opt.h:322
av_opt_get_sample_fmt
int av_opt_get_sample_fmt(void *obj, const char *name, int search_flags, enum AVSampleFormat *out_fmt)
Definition: opt.c:1009
av_opt_free
void av_opt_free(void *obj)
Free all allocated objects in obj.
Definition: opt.c:1611
AVOptionRanges::range
AVOptionRange ** range
Array of option ranges.
Definition: opt.h:364
AVOption::min
double min
minimum valid value for the option
Definition: opt.h:274
av_opt_get_int
int av_opt_get_int(void *obj, const char *name, int search_flags, int64_t *out_val)
Definition: opt.c:912
av_opt_set_int
int av_opt_set_int(void *obj, const char *name, int64_t val, int search_flags)
Definition: opt.c:586
options
const OptionDef options[]
av_opt_set_channel_layout
int av_opt_set_channel_layout(void *obj, const char *name, int64_t ch_layout, int search_flags)
Definition: opt.c:709
AVOptionRange
A single allowed range of values, or a single allowed value.
Definition: opt.h:310
AVOption::default_val
union AVOption::@312 default_val
the default value for scalar options
size
int size
Definition: twinvq_data.h:10344
av_opt_set_defaults2
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:1363
AVOption::name
const char * name
Definition: opt.h:249
AV_OPT_TYPE_CHANNEL_LAYOUT
@ AV_OPT_TYPE_CHANNEL_LAYOUT
Definition: opt.h:241
av_opt_eval_q
int av_opt_eval_q(void *obj, const AVOption *o, const char *val, AVRational *q_out)
av_opt_find2
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:1667
av_opt_set_dict2
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:1631
AVOption::q
AVRational q
Definition: opt.h:272
AV_OPT_TYPE_FLOAT
@ AV_OPT_TYPE_FLOAT
Definition: opt.h:228
log.h
AVOption::str
const char * str
Definition: opt.h:270
AVSampleFormat
AVSampleFormat
Audio sample formats.
Definition: samplefmt.h:58
AVOptionRanges
List of AVOptionRange structs.
Definition: opt.h:333
av_opt_next
const AVOption * av_opt_next(const void *obj, const AVOption *prev)
Iterate over all AVOptions belonging to obj.
Definition: opt.c:45
av_opt_eval_double
int av_opt_eval_double(void *obj, const AVOption *o, const char *val, double *double_out)
version.h
av_opt_eval_flags
int av_opt_eval_flags(void *obj, const AVOption *o, const char *val, int *flags_out)
AVOption::dbl
double dbl
Definition: opt.h:269
pixfmt.h
av_opt_eval_int
int av_opt_eval_int(void *obj, const AVOption *o, const char *val, int *int_out)
av_opt_get_key_value
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:1537
dict.h
AVOption::type
enum AVOptionType type
Definition: opt.h:262
av_opt_child_class_iterate
const AVClass * av_opt_child_class_iterate(const AVClass *parent, void **iter)
Iterate over potential AVOptions-enabled children of parent.
Definition: opt.c:1720
buffer
the frame and frame reference mechanism is intended to as much as expensive copies of that data while still allowing the filters to produce correct results The data is stored in buffers represented by AVFrame structures Several references can point to the same frame buffer
Definition: filter_design.txt:49
AV_OPT_TYPE_INT
@ AV_OPT_TYPE_INT
Definition: opt.h:225
AV_OPT_TYPE_PIXEL_FMT
@ AV_OPT_TYPE_PIXEL_FMT
Definition: opt.h:236
av_opt_serialize
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:2063
av_opt_flag_is_set
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:1048
av_opt_query_ranges_default
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:1849
av_opt_query_ranges
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:1828
av_opt_eval_float
int av_opt_eval_float(void *obj, const AVOption *o, const char *val, float *float_out)
avutil.h
AVOption::unit
const char * unit
The logical unit to which the option belongs.
Definition: opt.h:304
av_opt_freep_ranges
void av_opt_freep_ranges(AVOptionRanges **ranges)
Free an AVOptionRanges struct and set it to NULL.
Definition: opt.c:1921
av_opt_copy
int av_opt_copy(void *dest, const void *src)
Copy options from src object into dest object.
Definition: opt.c:1770
AVOptionRange::component_max
double component_max
Definition: opt.h:322
AV_OPT_TYPE_BOOL
@ AV_OPT_TYPE_BOOL
Definition: opt.h:242
AV_OPT_TYPE_FLAGS
@ AV_OPT_TYPE_FLAGS
Definition: opt.h:224
flags
#define flags(name, subs,...)
Definition: cbs_av1.c:561
av_opt_get
int av_opt_get(void *obj, const char *name, int search_flags, uint8_t **out_val)
Definition: opt.c:779
h
h
Definition: vp9dsp_template.c:2038
av_opt_get_image_size
int av_opt_get_image_size(void *obj, const char *name, int search_flags, int *w_out, int *h_out)
Definition: opt.c:952
AV_OPT_TYPE_STRING
@ AV_OPT_TYPE_STRING
Definition: opt.h:229
av_opt_set_q
int av_opt_set_q(void *obj, const char *name, AVRational val, int search_flags)
Definition: opt.c:596
av_opt_set_sample_fmt
int av_opt_set_sample_fmt(void *obj, const char *name, enum AVSampleFormat fmt, int search_flags)
Definition: opt.c:704
av_opt_show2
int av_opt_show2(void *obj, void *av_log_obj, int req_flags, int rej_flags)
Show the obj options.
Definition: opt.c:1346
AVOption::max
double max
maximum valid value for the option
Definition: opt.h:275
AV_OPT_TYPE_CONST
@ AV_OPT_TYPE_CONST
Definition: opt.h:234
av_opt_child_next
void * av_opt_child_next(void *obj, void *prev)
Iterate over AVOptions-enabled children of obj.
Definition: opt.c:1712
AV_OPT_TYPE_UINT64
@ AV_OPT_TYPE_UINT64
Definition: opt.h:233
av_opt_get_q
int av_opt_get_q(void *obj, const char *name, int search_flags, AVRational *out_val)
Definition: opt.c:936