1 /* 2 * AVOptions 3 * copyright (c) 2005 Michael Niedermayer <michaelni@gmx.at> 4 * 5 * This file is part of FFmpeg. 6 * 7 * FFmpeg is free software; you can redistribute it and/or 8 * modify it under the terms of the GNU Lesser General Public 9 * License as published by the Free Software Foundation; either 10 * version 2.1 of the License, or (at your option) any later version. 11 * 12 * FFmpeg is distributed in the hope that it will be useful, 13 * but WITHOUT ANY WARRANTY; without even the implied warranty of 14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 15 * Lesser General Public License for more details. 16 * 17 * You should have received a copy of the GNU Lesser General Public 18 * License along with FFmpeg; if not, write to the Free Software 19 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA 20 */ 21 22 #ifndef AVUTIL_OPT_H 23 #define AVUTIL_OPT_H 24 25 /** 26 * @file 27 * AVOptions 28 */ 29 30 #include "rational.h" 31 #include "avutil.h" 32 #include "dict.h" 33 #include "log.h" 34 #include "pixfmt.h" 35 #include "samplefmt.h" 36 #include "version.h" 37 38 /** 39 * @defgroup avoptions AVOptions 40 * @ingroup lavu_data 41 * @{ 42 * AVOptions provide a generic system to declare options on arbitrary structs 43 * ("objects"). An option can have a help text, a type and a range of possible 44 * values. Options may then be enumerated, read and written to. 45 * 46 * @section avoptions_implement Implementing AVOptions 47 * This section describes how to add AVOptions capabilities to a struct. 48 * 49 * All AVOptions-related information is stored in an AVClass. Therefore 50 * the first member of the struct should be a pointer to an AVClass describing it. 51 * The option field of the AVClass must be set to a NULL-terminated static array 52 * of AVOptions. Each AVOption must have a non-empty name, a type, a default 53 * value and for number-type AVOptions also a range of allowed values. It must 54 * also declare an offset in bytes from the start of the struct, where the field 55 * associated with this AVOption is located. Other fields in the AVOption struct 56 * should also be set when applicable, but are not required. 57 * 58 * The following example illustrates an AVOptions-enabled struct: 59 * @code 60 * typedef struct test_struct { 61 * const AVClass *class; 62 * int int_opt; 63 * char *str_opt; 64 * uint8_t *bin_opt; 65 * int bin_len; 66 * } test_struct; 67 * 68 * static const AVOption test_options[] = { 69 * { "test_int", "This is a test option of int type.", offsetof(test_struct, int_opt), 70 * AV_OPT_TYPE_INT, { .i64 = -1 }, INT_MIN, INT_MAX }, 71 * { "test_str", "This is a test option of string type.", offsetof(test_struct, str_opt), 72 * AV_OPT_TYPE_STRING }, 73 * { "test_bin", "This is a test option of binary type.", offsetof(test_struct, bin_opt), 74 * AV_OPT_TYPE_BINARY }, 75 * { NULL }, 76 * }; 77 * 78 * static const AVClass test_class = { 79 * .class_name = "test class", 80 * .item_name = av_default_item_name, 81 * .option = test_options, 82 * .version = LIBAVUTIL_VERSION_INT, 83 * }; 84 * @endcode 85 * 86 * Next, when allocating your struct, you must ensure that the AVClass pointer 87 * is set to the correct value. Then, av_opt_set_defaults() can be called to 88 * initialize defaults. After that the struct is ready to be used with the 89 * AVOptions API. 90 * 91 * When cleaning up, you may use the av_opt_free() function to automatically 92 * free all the allocated string and binary options. 93 * 94 * Continuing with the above example: 95 * 96 * @code 97 * test_struct *alloc_test_struct(void) 98 * { 99 * test_struct *ret = av_mallocz(sizeof(*ret)); 100 * ret->class = &test_class; 101 * av_opt_set_defaults(ret); 102 * return ret; 103 * } 104 * void free_test_struct(test_struct **foo) 105 * { 106 * av_opt_free(*foo); 107 * av_freep(foo); 108 * } 109 * @endcode 110 * 111 * @subsection avoptions_implement_nesting Nesting 112 * It may happen that an AVOptions-enabled struct contains another 113 * AVOptions-enabled struct as a member (e.g. AVCodecContext in 114 * libavcodec exports generic options, while its priv_data field exports 115 * codec-specific options). In such a case, it is possible to set up the 116 * parent struct to export a child's options. To do that, simply 117 * implement AVClass.child_next() and AVClass.child_class_next() in the 118 * parent struct's AVClass. 119 * Assuming that the test_struct from above now also contains a 120 * child_struct field: 121 * 122 * @code 123 * typedef struct child_struct { 124 * AVClass *class; 125 * int flags_opt; 126 * } child_struct; 127 * static const AVOption child_opts[] = { 128 * { "test_flags", "This is a test option of flags type.", 129 * offsetof(child_struct, flags_opt), AV_OPT_TYPE_FLAGS, { .i64 = 0 }, INT_MIN, INT_MAX }, 130 * { NULL }, 131 * }; 132 * static const AVClass child_class = { 133 * .class_name = "child class", 134 * .item_name = av_default_item_name, 135 * .option = child_opts, 136 * .version = LIBAVUTIL_VERSION_INT, 137 * }; 138 * 139 * void *child_next(void *obj, void *prev) 140 * { 141 * test_struct *t = obj; 142 * if (!prev && t->child_struct) 143 * return t->child_struct; 144 * return NULL 145 * } 146 * const AVClass child_class_next(const AVClass *prev) 147 * { 148 * return prev ? NULL : &child_class; 149 * } 150 * @endcode 151 * Putting child_next() and child_class_next() as defined above into 152 * test_class will now make child_struct's options accessible through 153 * test_struct (again, proper setup as described above needs to be done on 154 * child_struct right after it is created). 155 * 156 * From the above example it might not be clear why both child_next() 157 * and child_class_next() are needed. The distinction is that child_next() 158 * iterates over actually existing objects, while child_class_next() 159 * iterates over all possible child classes. E.g. if an AVCodecContext 160 * was initialized to use a codec which has private options, then its 161 * child_next() will return AVCodecContext.priv_data and finish 162 * iterating. OTOH child_class_next() on AVCodecContext.av_class will 163 * iterate over all available codecs with private options. 164 * 165 * @subsection avoptions_implement_named_constants Named constants 166 * It is possible to create named constants for options. Simply set the unit 167 * field of the option the constants should apply to a string and 168 * create the constants themselves as options of type AV_OPT_TYPE_CONST 169 * with their unit field set to the same string. 170 * Their default_val field should contain the value of the named 171 * constant. 172 * For example, to add some named constants for the test_flags option 173 * above, put the following into the child_opts array: 174 * @code 175 * { "test_flags", "This is a test option of flags type.", 176 * offsetof(child_struct, flags_opt), AV_OPT_TYPE_FLAGS, { .i64 = 0 }, INT_MIN, INT_MAX, "test_unit" }, 177 * { "flag1", "This is a flag with value 16", 0, AV_OPT_TYPE_CONST, { .i64 = 16 }, 0, 0, "test_unit" }, 178 * @endcode 179 * 180 * @section avoptions_use Using AVOptions 181 * This section deals with accessing options in an AVOptions-enabled struct. 182 * Such structs in FFmpeg are e.g. AVCodecContext in libavcodec or 183 * AVFormatContext in libavformat. 184 * 185 * @subsection avoptions_use_examine Examining AVOptions 186 * The basic functions for examining options are av_opt_next(), which iterates 187 * over all options defined for one object, and av_opt_find(), which searches 188 * for an option with the given name. 189 * 190 * The situation is more complicated with nesting. An AVOptions-enabled struct 191 * may have AVOptions-enabled children. Passing the AV_OPT_SEARCH_CHILDREN flag 192 * to av_opt_find() will make the function search children recursively. 193 * 194 * For enumerating there are basically two cases. The first is when you want to 195 * get all options that may potentially exist on the struct and its children 196 * (e.g. when constructing documentation). In that case you should call 197 * av_opt_child_class_next() recursively on the parent struct's AVClass. The 198 * second case is when you have an already initialized struct with all its 199 * children and you want to get all options that can be actually written or read 200 * from it. In that case you should call av_opt_child_next() recursively (and 201 * av_opt_next() on each result). 202 * 203 * @subsection avoptions_use_get_set Reading and writing AVOptions 204 * When setting options, you often have a string read directly from the 205 * user. In such a case, simply passing it to av_opt_set() is enough. For 206 * non-string type options, av_opt_set() will parse the string according to the 207 * option type. 208 * 209 * Similarly av_opt_get() will read any option type and convert it to a string 210 * which will be returned. Do not forget that the string is allocated, so you 211 * have to free it with av_free(). 212 * 213 * In some cases it may be more convenient to put all options into an 214 * AVDictionary and call av_opt_set_dict() on it. A specific case of this 215 * are the format/codec open functions in lavf/lavc which take a dictionary 216 * filled with option as a parameter. This makes it possible to set some options 217 * that cannot be set otherwise, since e.g. the input file format is not known 218 * before the file is actually opened. 219 */ 220 221 enum AVOptionType{ 222 AV_OPT_TYPE_FLAGS, 223 AV_OPT_TYPE_INT, 224 AV_OPT_TYPE_INT64, 225 AV_OPT_TYPE_DOUBLE, 226 AV_OPT_TYPE_FLOAT, 227 AV_OPT_TYPE_STRING, 228 AV_OPT_TYPE_RATIONAL, 229 AV_OPT_TYPE_BINARY, ///< offset must point to a pointer immediately followed by an int for the length 230 AV_OPT_TYPE_DICT, 231 AV_OPT_TYPE_UINT64, 232 AV_OPT_TYPE_CONST, 233 AV_OPT_TYPE_IMAGE_SIZE, ///< offset must point to two consecutive integers 234 AV_OPT_TYPE_PIXEL_FMT, 235 AV_OPT_TYPE_SAMPLE_FMT, 236 AV_OPT_TYPE_VIDEO_RATE, ///< offset must point to AVRational 237 AV_OPT_TYPE_DURATION, 238 AV_OPT_TYPE_COLOR, 239 AV_OPT_TYPE_CHANNEL_LAYOUT, 240 AV_OPT_TYPE_BOOL, 241 }; 242 243 /** 244 * AVOption 245 */ 246 typedef struct AVOption { 247 const char *name; 248 249 /** 250 * short English help text 251 * @todo What about other languages? 252 */ 253 const char *help; 254 255 /** 256 * The offset relative to the context structure where the option 257 * value is stored. It should be 0 for named constants. 258 */ 259 int offset; 260 enum AVOptionType type; 261 262 /** 263 * the default value for scalar options 264 */ 265 union { 266 int64_t i64; 267 double dbl; 268 const char *str; 269 /* TODO those are unused now */ 270 AVRational q; 271 } default_val; 272 double min; ///< minimum valid value for the option 273 double max; ///< maximum valid value for the option 274 275 int flags; 276 #define AV_OPT_FLAG_ENCODING_PARAM 1 ///< a generic parameter which can be set by the user for muxing or encoding 277 #define AV_OPT_FLAG_DECODING_PARAM 2 ///< a generic parameter which can be set by the user for demuxing or decoding 278 #define AV_OPT_FLAG_AUDIO_PARAM 8 279 #define AV_OPT_FLAG_VIDEO_PARAM 16 280 #define AV_OPT_FLAG_SUBTITLE_PARAM 32 281 /** 282 * The option is intended for exporting values to the caller. 283 */ 284 #define AV_OPT_FLAG_EXPORT 64 285 /** 286 * The option may not be set through the AVOptions API, only read. 287 * This flag only makes sense when AV_OPT_FLAG_EXPORT is also set. 288 */ 289 #define AV_OPT_FLAG_READONLY 128 290 #define AV_OPT_FLAG_BSF_PARAM (1<<8) ///< a generic parameter which can be set by the user for bit stream filtering 291 #define AV_OPT_FLAG_RUNTIME_PARAM (1<<15) ///< a generic parameter which can be set by the user at runtime 292 #define AV_OPT_FLAG_FILTERING_PARAM (1<<16) ///< a generic parameter which can be set by the user for filtering 293 #define AV_OPT_FLAG_DEPRECATED (1<<17) ///< set if option is deprecated, users should refer to AVOption.help text for more information 294 #define AV_OPT_FLAG_CHILD_CONSTS (1<<18) ///< set if option constants can also reside in child objects 295 //FIXME think about enc-audio, ... style flags 296 297 /** 298 * The logical unit to which the option belongs. Non-constant 299 * options and corresponding named constants share the same 300 * unit. May be NULL. 301 */ 302 const char *unit; 303 } AVOption; 304 305 /** 306 * A single allowed range of values, or a single allowed value. 307 */ 308 typedef struct AVOptionRange { 309 const char *str; 310 /** 311 * Value range. 312 * For string ranges this represents the min/max length. 313 * For dimensions this represents the min/max pixel count or width/height in multi-component case. 314 */ 315 double value_min, value_max; 316 /** 317 * Value's component range. 318 * For string this represents the unicode range for chars, 0-127 limits to ASCII. 319 */ 320 double component_min, component_max; 321 /** 322 * Range flag. 323 * If set to 1 the struct encodes a range, if set to 0 a single value. 324 */ 325 int is_range; 326 } AVOptionRange; 327 328 /** 329 * List of AVOptionRange structs. 330 */ 331 typedef struct AVOptionRanges { 332 /** 333 * Array of option ranges. 334 * 335 * Most of option types use just one component. 336 * Following describes multi-component option types: 337 * 338 * AV_OPT_TYPE_IMAGE_SIZE: 339 * component index 0: range of pixel count (width * height). 340 * component index 1: range of width. 341 * component index 2: range of height. 342 * 343 * @note To obtain multi-component version of this structure, user must 344 * provide AV_OPT_MULTI_COMPONENT_RANGE to av_opt_query_ranges or 345 * av_opt_query_ranges_default function. 346 * 347 * Multi-component range can be read as in following example: 348 * 349 * @code 350 * int range_index, component_index; 351 * AVOptionRanges *ranges; 352 * AVOptionRange *range[3]; //may require more than 3 in the future. 353 * av_opt_query_ranges(&ranges, obj, key, AV_OPT_MULTI_COMPONENT_RANGE); 354 * for (range_index = 0; range_index < ranges->nb_ranges; range_index++) { 355 * for (component_index = 0; component_index < ranges->nb_components; component_index++) 356 * range[component_index] = ranges->range[ranges->nb_ranges * component_index + range_index]; 357 * //do something with range here. 358 * } 359 * av_opt_freep_ranges(&ranges); 360 * @endcode 361 */ 362 AVOptionRange **range; 363 /** 364 * Number of ranges per component. 365 */ 366 int nb_ranges; 367 /** 368 * Number of componentes. 369 */ 370 int nb_components; 371 } AVOptionRanges; 372 373 /** 374 * Show the obj options. 375 * 376 * @param req_flags requested flags for the options to show. Show only the 377 * options for which it is opt->flags & req_flags. 378 * @param rej_flags rejected flags for the options to show. Show only the 379 * options for which it is !(opt->flags & req_flags). 380 * @param av_log_obj log context to use for showing the options 381 */ 382 int av_opt_show2(void *obj, void *av_log_obj, int req_flags, int rej_flags); 383 384 /** 385 * Set the values of all AVOption fields to their default values. 386 * 387 * @param s an AVOption-enabled struct (its first member must be a pointer to AVClass) 388 */ 389 void av_opt_set_defaults(void *s); 390 391 /** 392 * Set the values of all AVOption fields to their default values. Only these 393 * AVOption fields for which (opt->flags & mask) == flags will have their 394 * default applied to s. 395 * 396 * @param s an AVOption-enabled struct (its first member must be a pointer to AVClass) 397 * @param mask combination of AV_OPT_FLAG_* 398 * @param flags combination of AV_OPT_FLAG_* 399 */ 400 void av_opt_set_defaults2(void *s, int mask, int flags); 401 402 /** 403 * Parse the key/value pairs list in opts. For each key/value pair 404 * found, stores the value in the field in ctx that is named like the 405 * key. ctx must be an AVClass context, storing is done using 406 * AVOptions. 407 * 408 * @param opts options string to parse, may be NULL 409 * @param key_val_sep a 0-terminated list of characters used to 410 * separate key from value 411 * @param pairs_sep a 0-terminated list of characters used to separate 412 * two pairs from each other 413 * @return the number of successfully set key/value pairs, or a negative 414 * value corresponding to an AVERROR code in case of error: 415 * AVERROR(EINVAL) if opts cannot be parsed, 416 * the error code issued by av_opt_set() if a key/value pair 417 * cannot be set 418 */ 419 int av_set_options_string(void *ctx, const char *opts, 420 const char *key_val_sep, const char *pairs_sep); 421 422 /** 423 * Parse the key-value pairs list in opts. For each key=value pair found, 424 * set the value of the corresponding option in ctx. 425 * 426 * @param ctx the AVClass object to set options on 427 * @param opts the options string, key-value pairs separated by a 428 * delimiter 429 * @param shorthand a NULL-terminated array of options names for shorthand 430 * notation: if the first field in opts has no key part, 431 * the key is taken from the first element of shorthand; 432 * then again for the second, etc., until either opts is 433 * finished, shorthand is finished or a named option is 434 * found; after that, all options must be named 435 * @param key_val_sep a 0-terminated list of characters used to separate 436 * key from value, for example '=' 437 * @param pairs_sep a 0-terminated list of characters used to separate 438 * two pairs from each other, for example ':' or ',' 439 * @return the number of successfully set key=value pairs, or a negative 440 * value corresponding to an AVERROR code in case of error: 441 * AVERROR(EINVAL) if opts cannot be parsed, 442 * the error code issued by av_set_string3() if a key/value pair 443 * cannot be set 444 * 445 * Options names must use only the following characters: a-z A-Z 0-9 - . / _ 446 * Separators must use characters distinct from option names and from each 447 * other. 448 */ 449 int av_opt_set_from_string(void *ctx, const char *opts, 450 const char *const *shorthand, 451 const char *key_val_sep, const char *pairs_sep); 452 /** 453 * Free all allocated objects in obj. 454 */ 455 void av_opt_free(void *obj); 456 457 /** 458 * Check whether a particular flag is set in a flags field. 459 * 460 * @param field_name the name of the flag field option 461 * @param flag_name the name of the flag to check 462 * @return non-zero if the flag is set, zero if the flag isn't set, 463 * isn't of the right type, or the flags field doesn't exist. 464 */ 465 int av_opt_flag_is_set(void *obj, const char *field_name, const char *flag_name); 466 467 /** 468 * Set all the options from a given dictionary on an object. 469 * 470 * @param obj a struct whose first element is a pointer to AVClass 471 * @param options options to process. This dictionary will be freed and replaced 472 * by a new one containing all options not found in obj. 473 * Of course this new dictionary needs to be freed by caller 474 * with av_dict_free(). 475 * 476 * @return 0 on success, a negative AVERROR if some option was found in obj, 477 * but could not be set. 478 * 479 * @see av_dict_copy() 480 */ 481 int av_opt_set_dict(void *obj, struct AVDictionary **options); 482 483 484 /** 485 * Set all the options from a given dictionary on an object. 486 * 487 * @param obj a struct whose first element is a pointer to AVClass 488 * @param options options to process. This dictionary will be freed and replaced 489 * by a new one containing all options not found in obj. 490 * Of course this new dictionary needs to be freed by caller 491 * with av_dict_free(). 492 * @param search_flags A combination of AV_OPT_SEARCH_*. 493 * 494 * @return 0 on success, a negative AVERROR if some option was found in obj, 495 * but could not be set. 496 * 497 * @see av_dict_copy() 498 */ 499 int av_opt_set_dict2(void *obj, struct AVDictionary **options, int search_flags); 500 501 /** 502 * Extract a key-value pair from the beginning of a string. 503 * 504 * @param ropts pointer to the options string, will be updated to 505 * point to the rest of the string (one of the pairs_sep 506 * or the final NUL) 507 * @param key_val_sep a 0-terminated list of characters used to separate 508 * key from value, for example '=' 509 * @param pairs_sep a 0-terminated list of characters used to separate 510 * two pairs from each other, for example ':' or ',' 511 * @param flags flags; see the AV_OPT_FLAG_* values below 512 * @param rkey parsed key; must be freed using av_free() 513 * @param rval parsed value; must be freed using av_free() 514 * 515 * @return >=0 for success, or a negative value corresponding to an 516 * AVERROR code in case of error; in particular: 517 * AVERROR(EINVAL) if no key is present 518 * 519 */ 520 int av_opt_get_key_value(const char **ropts, 521 const char *key_val_sep, const char *pairs_sep, 522 unsigned flags, 523 char **rkey, char **rval); 524 525 enum { 526 527 /** 528 * Accept to parse a value without a key; the key will then be returned 529 * as NULL. 530 */ 531 AV_OPT_FLAG_IMPLICIT_KEY = 1, 532 }; 533 534 /** 535 * @defgroup opt_eval_funcs Evaluating option strings 536 * @{ 537 * This group of functions can be used to evaluate option strings 538 * and get numbers out of them. They do the same thing as av_opt_set(), 539 * except the result is written into the caller-supplied pointer. 540 * 541 * @param obj a struct whose first element is a pointer to AVClass. 542 * @param o an option for which the string is to be evaluated. 543 * @param val string to be evaluated. 544 * @param *_out value of the string will be written here. 545 * 546 * @return 0 on success, a negative number on failure. 547 */ 548 int av_opt_eval_flags (void *obj, const AVOption *o, const char *val, int *flags_out); 549 int av_opt_eval_int (void *obj, const AVOption *o, const char *val, int *int_out); 550 int av_opt_eval_int64 (void *obj, const AVOption *o, const char *val, int64_t *int64_out); 551 int av_opt_eval_float (void *obj, const AVOption *o, const char *val, float *float_out); 552 int av_opt_eval_double(void *obj, const AVOption *o, const char *val, double *double_out); 553 int av_opt_eval_q (void *obj, const AVOption *o, const char *val, AVRational *q_out); 554 /** 555 * @} 556 */ 557 558 #define AV_OPT_SEARCH_CHILDREN (1 << 0) /**< Search in possible children of the 559 given object first. */ 560 /** 561 * The obj passed to av_opt_find() is fake -- only a double pointer to AVClass 562 * instead of a required pointer to a struct containing AVClass. This is 563 * useful for searching for options without needing to allocate the corresponding 564 * object. 565 */ 566 #define AV_OPT_SEARCH_FAKE_OBJ (1 << 1) 567 568 /** 569 * In av_opt_get, return NULL if the option has a pointer type and is set to NULL, 570 * rather than returning an empty string. 571 */ 572 #define AV_OPT_ALLOW_NULL (1 << 2) 573 574 /** 575 * Allows av_opt_query_ranges and av_opt_query_ranges_default to return more than 576 * one component for certain option types. 577 * @see AVOptionRanges for details. 578 */ 579 #define AV_OPT_MULTI_COMPONENT_RANGE (1 << 12) 580 581 /** 582 * Look for an option in an object. Consider only options which 583 * have all the specified flags set. 584 * 585 * @param[in] obj A pointer to a struct whose first element is a 586 * pointer to an AVClass. 587 * Alternatively a double pointer to an AVClass, if 588 * AV_OPT_SEARCH_FAKE_OBJ search flag is set. 589 * @param[in] name The name of the option to look for. 590 * @param[in] unit When searching for named constants, name of the unit 591 * it belongs to. 592 * @param opt_flags Find only options with all the specified flags set (AV_OPT_FLAG). 593 * @param search_flags A combination of AV_OPT_SEARCH_*. 594 * 595 * @return A pointer to the option found, or NULL if no option 596 * was found. 597 * 598 * @note Options found with AV_OPT_SEARCH_CHILDREN flag may not be settable 599 * directly with av_opt_set(). Use special calls which take an options 600 * AVDictionary (e.g. avformat_open_input()) to set options found with this 601 * flag. 602 */ 603 const AVOption *av_opt_find(void *obj, const char *name, const char *unit, 604 int opt_flags, int search_flags); 605 606 /** 607 * Look for an option in an object. Consider only options which 608 * have all the specified flags set. 609 * 610 * @param[in] obj A pointer to a struct whose first element is a 611 * pointer to an AVClass. 612 * Alternatively a double pointer to an AVClass, if 613 * AV_OPT_SEARCH_FAKE_OBJ search flag is set. 614 * @param[in] name The name of the option to look for. 615 * @param[in] unit When searching for named constants, name of the unit 616 * it belongs to. 617 * @param opt_flags Find only options with all the specified flags set (AV_OPT_FLAG). 618 * @param search_flags A combination of AV_OPT_SEARCH_*. 619 * @param[out] target_obj if non-NULL, an object to which the option belongs will be 620 * written here. It may be different from obj if AV_OPT_SEARCH_CHILDREN is present 621 * in search_flags. This parameter is ignored if search_flags contain 622 * AV_OPT_SEARCH_FAKE_OBJ. 623 * 624 * @return A pointer to the option found, or NULL if no option 625 * was found. 626 */ 627 const AVOption *av_opt_find2(void *obj, const char *name, const char *unit, 628 int opt_flags, int search_flags, void **target_obj); 629 630 /** 631 * Iterate over all AVOptions belonging to obj. 632 * 633 * @param obj an AVOptions-enabled struct or a double pointer to an 634 * AVClass describing it. 635 * @param prev result of the previous call to av_opt_next() on this object 636 * or NULL 637 * @return next AVOption or NULL 638 */ 639 const AVOption *av_opt_next(const void *obj, const AVOption *prev); 640 641 /** 642 * Iterate over AVOptions-enabled children of obj. 643 * 644 * @param prev result of a previous call to this function or NULL 645 * @return next AVOptions-enabled child or NULL 646 */ 647 void *av_opt_child_next(void *obj, void *prev); 648 649 /** 650 * Iterate over potential AVOptions-enabled children of parent. 651 * 652 * @param prev result of a previous call to this function or NULL 653 * @return AVClass corresponding to next potential child or NULL 654 */ 655 const AVClass *av_opt_child_class_next(const AVClass *parent, const AVClass *prev); 656 657 /** 658 * @defgroup opt_set_funcs Option setting functions 659 * @{ 660 * Those functions set the field of obj with the given name to value. 661 * 662 * @param[in] obj A struct whose first element is a pointer to an AVClass. 663 * @param[in] name the name of the field to set 664 * @param[in] val The value to set. In case of av_opt_set() if the field is not 665 * of a string type, then the given string is parsed. 666 * SI postfixes and some named scalars are supported. 667 * If the field is of a numeric type, it has to be a numeric or named 668 * scalar. Behavior with more than one scalar and +- infix operators 669 * is undefined. 670 * If the field is of a flags type, it has to be a sequence of numeric 671 * scalars or named flags separated by '+' or '-'. Prefixing a flag 672 * with '+' causes it to be set without affecting the other flags; 673 * similarly, '-' unsets a flag. 674 * If the field is of a dictionary type, it has to be a ':' separated list of 675 * key=value parameters. Values containing ':' special characters must be 676 * escaped. 677 * @param search_flags flags passed to av_opt_find2. I.e. if AV_OPT_SEARCH_CHILDREN 678 * is passed here, then the option may be set on a child of obj. 679 * 680 * @return 0 if the value has been set, or an AVERROR code in case of 681 * error: 682 * AVERROR_OPTION_NOT_FOUND if no matching option exists 683 * AVERROR(ERANGE) if the value is out of range 684 * AVERROR(EINVAL) if the value is not valid 685 */ 686 int av_opt_set (void *obj, const char *name, const char *val, int search_flags); 687 int av_opt_set_int (void *obj, const char *name, int64_t val, int search_flags); 688 int av_opt_set_double (void *obj, const char *name, double val, int search_flags); 689 int av_opt_set_q (void *obj, const char *name, AVRational val, int search_flags); 690 int av_opt_set_bin (void *obj, const char *name, const uint8_t *val, int size, int search_flags); 691 int av_opt_set_image_size(void *obj, const char *name, int w, int h, int search_flags); 692 int av_opt_set_pixel_fmt (void *obj, const char *name, enum AVPixelFormat fmt, int search_flags); 693 int av_opt_set_sample_fmt(void *obj, const char *name, enum AVSampleFormat fmt, int search_flags); 694 int av_opt_set_video_rate(void *obj, const char *name, AVRational val, int search_flags); 695 int av_opt_set_channel_layout(void *obj, const char *name, int64_t ch_layout, int search_flags); 696 /** 697 * @note Any old dictionary present is discarded and replaced with a copy of the new one. The 698 * caller still owns val is and responsible for freeing it. 699 */ 700 int av_opt_set_dict_val(void *obj, const char *name, const AVDictionary *val, int search_flags); 701 702 /** 703 * Set a binary option to an integer list. 704 * 705 * @param obj AVClass object to set options on 706 * @param name name of the binary option 707 * @param val pointer to an integer list (must have the correct type with 708 * regard to the contents of the list) 709 * @param term list terminator (usually 0 or -1) 710 * @param flags search flags 711 */ 712 #define av_opt_set_int_list(obj, name, val, term, flags) \ 713 (av_int_list_length(val, term) > INT_MAX / sizeof(*(val)) ? \ 714 AVERROR(EINVAL) : \ 715 av_opt_set_bin(obj, name, (const uint8_t *)(val), \ 716 av_int_list_length(val, term) * sizeof(*(val)), flags)) 717 718 /** 719 * @} 720 */ 721 722 /** 723 * @defgroup opt_get_funcs Option getting functions 724 * @{ 725 * Those functions get a value of the option with the given name from an object. 726 * 727 * @param[in] obj a struct whose first element is a pointer to an AVClass. 728 * @param[in] name name of the option to get. 729 * @param[in] search_flags flags passed to av_opt_find2. I.e. if AV_OPT_SEARCH_CHILDREN 730 * is passed here, then the option may be found in a child of obj. 731 * @param[out] out_val value of the option will be written here 732 * @return >=0 on success, a negative error code otherwise 733 */ 734 /** 735 * @note the returned string will be av_malloc()ed and must be av_free()ed by the caller 736 * 737 * @note if AV_OPT_ALLOW_NULL is set in search_flags in av_opt_get, and the 738 * option is of type AV_OPT_TYPE_STRING, AV_OPT_TYPE_BINARY or AV_OPT_TYPE_DICT 739 * and is set to NULL, *out_val will be set to NULL instead of an allocated 740 * empty string. 741 */ 742 int av_opt_get (void *obj, const char *name, int search_flags, uint8_t **out_val); 743 int av_opt_get_int (void *obj, const char *name, int search_flags, int64_t *out_val); 744 int av_opt_get_double (void *obj, const char *name, int search_flags, double *out_val); 745 int av_opt_get_q (void *obj, const char *name, int search_flags, AVRational *out_val); 746 int av_opt_get_image_size(void *obj, const char *name, int search_flags, int *w_out, int *h_out); 747 int av_opt_get_pixel_fmt (void *obj, const char *name, int search_flags, enum AVPixelFormat *out_fmt); 748 int av_opt_get_sample_fmt(void *obj, const char *name, int search_flags, enum AVSampleFormat *out_fmt); 749 int av_opt_get_video_rate(void *obj, const char *name, int search_flags, AVRational *out_val); 750 int av_opt_get_channel_layout(void *obj, const char *name, int search_flags, int64_t *ch_layout); 751 /** 752 * @param[out] out_val The returned dictionary is a copy of the actual value and must 753 * be freed with av_dict_free() by the caller 754 */ 755 int av_opt_get_dict_val(void *obj, const char *name, int search_flags, AVDictionary **out_val); 756 /** 757 * @} 758 */ 759 /** 760 * Gets a pointer to the requested field in a struct. 761 * This function allows accessing a struct even when its fields are moved or 762 * renamed since the application making the access has been compiled, 763 * 764 * @returns a pointer to the field, it can be cast to the correct type and read 765 * or written to. 766 */ 767 void *av_opt_ptr(const AVClass *avclass, void *obj, const char *name); 768 769 /** 770 * Free an AVOptionRanges struct and set it to NULL. 771 */ 772 void av_opt_freep_ranges(AVOptionRanges **ranges); 773 774 /** 775 * Get a list of allowed ranges for the given option. 776 * 777 * The returned list may depend on other fields in obj like for example profile. 778 * 779 * @param flags is a bitmask of flags, undefined flags should not be set and should be ignored 780 * AV_OPT_SEARCH_FAKE_OBJ indicates that the obj is a double pointer to a AVClass instead of a full instance 781 * AV_OPT_MULTI_COMPONENT_RANGE indicates that function may return more than one component, @see AVOptionRanges 782 * 783 * The result must be freed with av_opt_freep_ranges. 784 * 785 * @return number of compontents returned on success, a negative errro code otherwise 786 */ 787 int av_opt_query_ranges(AVOptionRanges **, void *obj, const char *key, int flags); 788 789 /** 790 * Copy options from src object into dest object. 791 * 792 * Options that require memory allocation (e.g. string or binary) are malloc'ed in dest object. 793 * Original memory allocated for such options is freed unless both src and dest options points to the same memory. 794 * 795 * @param dest Object to copy from 796 * @param src Object to copy into 797 * @return 0 on success, negative on error 798 */ 799 int av_opt_copy(void *dest, const void *src); 800 801 /** 802 * Get a default list of allowed ranges for the given option. 803 * 804 * This list is constructed without using the AVClass.query_ranges() callback 805 * and can be used as fallback from within the callback. 806 * 807 * @param flags is a bitmask of flags, undefined flags should not be set and should be ignored 808 * AV_OPT_SEARCH_FAKE_OBJ indicates that the obj is a double pointer to a AVClass instead of a full instance 809 * AV_OPT_MULTI_COMPONENT_RANGE indicates that function may return more than one component, @see AVOptionRanges 810 * 811 * The result must be freed with av_opt_free_ranges. 812 * 813 * @return number of compontents returned on success, a negative errro code otherwise 814 */ 815 int av_opt_query_ranges_default(AVOptionRanges **, void *obj, const char *key, int flags); 816 817 /** 818 * Check if given option is set to its default value. 819 * 820 * Options o must belong to the obj. This function must not be called to check child's options state. 821 * @see av_opt_is_set_to_default_by_name(). 822 * 823 * @param obj AVClass object to check option on 824 * @param o option to be checked 825 * @return >0 when option is set to its default, 826 * 0 when option is not set its default, 827 * <0 on error 828 */ 829 int av_opt_is_set_to_default(void *obj, const AVOption *o); 830 831 /** 832 * Check if given option is set to its default value. 833 * 834 * @param obj AVClass object to check option on 835 * @param name option name 836 * @param search_flags combination of AV_OPT_SEARCH_* 837 * @return >0 when option is set to its default, 838 * 0 when option is not set its default, 839 * <0 on error 840 */ 841 int av_opt_is_set_to_default_by_name(void *obj, const char *name, int search_flags); 842 843 844 #define AV_OPT_SERIALIZE_SKIP_DEFAULTS 0x00000001 ///< Serialize options that are not set to default values only. 845 #define AV_OPT_SERIALIZE_OPT_FLAGS_EXACT 0x00000002 ///< Serialize options that exactly match opt_flags only. 846 847 /** 848 * Serialize object's options. 849 * 850 * Create a string containing object's serialized options. 851 * Such string may be passed back to av_opt_set_from_string() in order to restore option values. 852 * A key/value or pairs separator occurring in the serialized value or 853 * name string are escaped through the av_escape() function. 854 * 855 * @param[in] obj AVClass object to serialize 856 * @param[in] opt_flags serialize options with all the specified flags set (AV_OPT_FLAG) 857 * @param[in] flags combination of AV_OPT_SERIALIZE_* flags 858 * @param[out] buffer Pointer to buffer that will be allocated with string containg serialized options. 859 * Buffer must be freed by the caller when is no longer needed. 860 * @param[in] key_val_sep character used to separate key from value 861 * @param[in] pairs_sep character used to separate two pairs from each other 862 * @return >= 0 on success, negative on error 863 * @warning Separators cannot be neither '\\' nor '\0'. They also cannot be the same. 864 */ 865 int av_opt_serialize(void *obj, int opt_flags, int flags, char **buffer, 866 const char key_val_sep, const char pairs_sep); 867 /** 868 * @} 869 */ 870 871 #endif /* AVUTIL_OPT_H */ 872