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 37 /** 38 * @defgroup avoptions AVOptions 39 * @ingroup lavu_data 40 * @{ 41 * AVOptions provide a generic system to declare options on arbitrary structs 42 * ("objects"). An option can have a help text, a type and a range of possible 43 * values. Options may then be enumerated, read and written to. 44 * 45 * @section avoptions_implement Implementing AVOptions 46 * This section describes how to add AVOptions capabilities to a struct. 47 * 48 * All AVOptions-related information is stored in an AVClass. Therefore 49 * the first member of the struct should be a pointer to an AVClass describing it. 50 * The option field of the AVClass must be set to a NULL-terminated static array 51 * of AVOptions. Each AVOption must have a non-empty name, a type, a default 52 * value and for number-type AVOptions also a range of allowed values. It must 53 * also declare an offset in bytes from the start of the struct, where the field 54 * associated with this AVOption is located. Other fields in the AVOption struct 55 * should also be set when applicable, but are not required. 56 * 57 * The following example illustrates an AVOptions-enabled struct: 58 * @code 59 * typedef struct test_struct { 60 * AVClass *class; 61 * int int_opt; 62 * char *str_opt; 63 * uint8_t *bin_opt; 64 * int bin_len; 65 * } test_struct; 66 * 67 * static const AVOption options[] = { 68 * { "test_int", "This is a test option of int type.", offsetof(test_struct, int_opt), 69 * AV_OPT_TYPE_INT, { .i64 = -1 }, INT_MIN, INT_MAX }, 70 * { "test_str", "This is a test option of string type.", offsetof(test_struct, str_opt), 71 * AV_OPT_TYPE_STRING }, 72 * { "test_bin", "This is a test option of binary type.", offsetof(test_struct, bin_opt), 73 * AV_OPT_TYPE_BINARY }, 74 * { NULL }, 75 * }; 76 * 77 * static const AVClass test_class = { 78 * .class_name = "test class", 79 * .item_name = av_default_item_name, 80 * .option = options, 81 * .version = LIBAVUTIL_VERSION_INT, 82 * }; 83 * @endcode 84 * 85 * Next, when allocating your struct, you must ensure that the AVClass pointer 86 * is set to the correct value. Then, av_opt_set_defaults() can be called to 87 * initialize defaults. After that the struct is ready to be used with the 88 * AVOptions API. 89 * 90 * When cleaning up, you may use the av_opt_free() function to automatically 91 * free all the allocated string and binary options. 92 * 93 * Continuing with the above example: 94 * 95 * @code 96 * test_struct *alloc_test_struct(void) 97 * { 98 * test_struct *ret = av_malloc(sizeof(*ret)); 99 * ret->class = &test_class; 100 * av_opt_set_defaults(ret); 101 * return ret; 102 * } 103 * void free_test_struct(test_struct **foo) 104 * { 105 * av_opt_free(*foo); 106 * av_freep(foo); 107 * } 108 * @endcode 109 * 110 * @subsection avoptions_implement_nesting Nesting 111 * It may happen that an AVOptions-enabled struct contains another 112 * AVOptions-enabled struct as a member (e.g. AVCodecContext in 113 * libavcodec exports generic options, while its priv_data field exports 114 * codec-specific options). In such a case, it is possible to set up the 115 * parent struct to export a child's options. To do that, simply 116 * implement AVClass.child_next() and AVClass.child_class_next() in the 117 * parent struct's AVClass. 118 * Assuming that the test_struct from above now also contains a 119 * child_struct field: 120 * 121 * @code 122 * typedef struct child_struct { 123 * AVClass *class; 124 * int flags_opt; 125 * } child_struct; 126 * static const AVOption child_opts[] = { 127 * { "test_flags", "This is a test option of flags type.", 128 * offsetof(child_struct, flags_opt), AV_OPT_TYPE_FLAGS, { .i64 = 0 }, INT_MIN, INT_MAX }, 129 * { NULL }, 130 * }; 131 * static const AVClass child_class = { 132 * .class_name = "child class", 133 * .item_name = av_default_item_name, 134 * .option = child_opts, 135 * .version = LIBAVUTIL_VERSION_INT, 136 * }; 137 * 138 * void *child_next(void *obj, void *prev) 139 * { 140 * test_struct *t = obj; 141 * if (!prev && t->child_struct) 142 * return t->child_struct; 143 * return NULL 144 * } 145 * const AVClass child_class_next(const AVClass *prev) 146 * { 147 * return prev ? NULL : &child_class; 148 * } 149 * @endcode 150 * Putting child_next() and child_class_next() as defined above into 151 * test_class will now make child_struct's options accessible through 152 * test_struct (again, proper setup as described above needs to be done on 153 * child_struct right after it is created). 154 * 155 * From the above example it might not be clear why both child_next() 156 * and child_class_next() are needed. The distinction is that child_next() 157 * iterates over actually existing objects, while child_class_next() 158 * iterates over all possible child classes. E.g. if an AVCodecContext 159 * was initialized to use a codec which has private options, then its 160 * child_next() will return AVCodecContext.priv_data and finish 161 * iterating. OTOH child_class_next() on AVCodecContext.av_class will 162 * iterate over all available codecs with private options. 163 * 164 * @subsection avoptions_implement_named_constants Named constants 165 * It is possible to create named constants for options. Simply set the unit 166 * field of the option the constants should apply to to a string and 167 * create the constants themselves as options of type AV_OPT_TYPE_CONST 168 * with their unit field set to the same string. 169 * Their default_val field should contain the value of the named 170 * constant. 171 * For example, to add some named constants for the test_flags option 172 * above, put the following into the child_opts array: 173 * @code 174 * { "test_flags", "This is a test option of flags type.", 175 * offsetof(child_struct, flags_opt), AV_OPT_TYPE_FLAGS, { .i64 = 0 }, INT_MIN, INT_MAX, "test_unit" }, 176 * { "flag1", "This is a flag with value 16", 0, AV_OPT_TYPE_CONST, { .i64 = 16 }, 0, 0, "test_unit" }, 177 * @endcode 178 * 179 * @section avoptions_use Using AVOptions 180 * This section deals with accessing options in an AVOptions-enabled struct. 181 * Such structs in FFmpeg are e.g. AVCodecContext in libavcodec or 182 * AVFormatContext in libavformat. 183 * 184 * @subsection avoptions_use_examine Examining AVOptions 185 * The basic functions for examining options are av_opt_next(), which iterates 186 * over all options defined for one object, and av_opt_find(), which searches 187 * for an option with the given name. 188 * 189 * The situation is more complicated with nesting. An AVOptions-enabled struct 190 * may have AVOptions-enabled children. Passing the AV_OPT_SEARCH_CHILDREN flag 191 * to av_opt_find() will make the function search children recursively. 192 * 193 * For enumerating there are basically two cases. The first is when you want to 194 * get all options that may potentially exist on the struct and its children 195 * (e.g. when constructing documentation). In that case you should call 196 * av_opt_child_class_next() recursively on the parent struct's AVClass. The 197 * second case is when you have an already initialized struct with all its 198 * children and you want to get all options that can be actually written or read 199 * from it. In that case you should call av_opt_child_next() recursively (and 200 * av_opt_next() on each result). 201 * 202 * @subsection avoptions_use_get_set Reading and writing AVOptions 203 * When setting options, you often have a string read directly from the 204 * user. In such a case, simply passing it to av_opt_set() is enough. For 205 * non-string type options, av_opt_set() will parse the string according to the 206 * option type. 207 * 208 * Similarly av_opt_get() will read any option type and convert it to a string 209 * which will be returned. Do not forget that the string is allocated, so you 210 * have to free it with av_free(). 211 * 212 * In some cases it may be more convenient to put all options into an 213 * AVDictionary and call av_opt_set_dict() on it. A specific case of this 214 * are the format/codec open functions in lavf/lavc which take a dictionary 215 * filled with option as a parameter. This allows to set some options 216 * that cannot be set otherwise, since e.g. the input file format is not known 217 * before the file is actually opened. 218 */ 219 220 enum AVOptionType{ 221 AV_OPT_TYPE_FLAGS, 222 AV_OPT_TYPE_INT, 223 AV_OPT_TYPE_INT64, 224 AV_OPT_TYPE_DOUBLE, 225 AV_OPT_TYPE_FLOAT, 226 AV_OPT_TYPE_STRING, 227 AV_OPT_TYPE_RATIONAL, 228 AV_OPT_TYPE_BINARY, ///< offset must point to a pointer immediately followed by an int for the length 229 AV_OPT_TYPE_CONST = 128, 230 AV_OPT_TYPE_IMAGE_SIZE = MKBETAG('S','I','Z','E'), ///< offset must point to two consecutive integers 231 AV_OPT_TYPE_PIXEL_FMT = MKBETAG('P','F','M','T'), 232 AV_OPT_TYPE_SAMPLE_FMT = MKBETAG('S','F','M','T'), 233 AV_OPT_TYPE_VIDEO_RATE = MKBETAG('V','R','A','T'), ///< offset must point to AVRational 234 AV_OPT_TYPE_DURATION = MKBETAG('D','U','R',' '), 235 AV_OPT_TYPE_COLOR = MKBETAG('C','O','L','R'), 236 #if FF_API_OLD_AVOPTIONS 237 FF_OPT_TYPE_FLAGS = 0, 238 FF_OPT_TYPE_INT, 239 FF_OPT_TYPE_INT64, 240 FF_OPT_TYPE_DOUBLE, 241 FF_OPT_TYPE_FLOAT, 242 FF_OPT_TYPE_STRING, 243 FF_OPT_TYPE_RATIONAL, 244 FF_OPT_TYPE_BINARY, ///< offset must point to a pointer immediately followed by an int for the length 245 FF_OPT_TYPE_CONST=128, 246 #endif 247 }; 248 249 /** 250 * AVOption 251 */ 252 typedef struct AVOption { 253 const char *name; 254 255 /** 256 * short English help text 257 * @todo What about other languages? 258 */ 259 const char *help; 260 261 /** 262 * The offset relative to the context structure where the option 263 * value is stored. It should be 0 for named constants. 264 */ 265 int offset; 266 enum AVOptionType type; 267 268 /** 269 * the default value for scalar options 270 */ 271 union { 272 int64_t i64; 273 double dbl; 274 const char *str; 275 /* TODO those are unused now */ 276 AVRational q; 277 } default_val; 278 double min; ///< minimum valid value for the option 279 double max; ///< maximum valid value for the option 280 281 int flags; 282 #define AV_OPT_FLAG_ENCODING_PARAM 1 ///< a generic parameter which can be set by the user for muxing or encoding 283 #define AV_OPT_FLAG_DECODING_PARAM 2 ///< a generic parameter which can be set by the user for demuxing or decoding 284 #define AV_OPT_FLAG_METADATA 4 ///< some data extracted or inserted into the file like title, comment, ... 285 #define AV_OPT_FLAG_AUDIO_PARAM 8 286 #define AV_OPT_FLAG_VIDEO_PARAM 16 287 #define AV_OPT_FLAG_SUBTITLE_PARAM 32 288 #define AV_OPT_FLAG_FILTERING_PARAM (1<<16) ///< a generic parameter which can be set by the user for filtering 289 //FIXME think about enc-audio, ... style flags 290 291 /** 292 * The logical unit to which the option belongs. Non-constant 293 * options and corresponding named constants share the same 294 * unit. May be NULL. 295 */ 296 const char *unit; 297 } AVOption; 298 299 /** 300 * A single allowed range of values, or a single allowed value. 301 */ 302 typedef struct AVOptionRange { 303 const char *str; 304 double value_min, value_max; ///< For string ranges this represents the min/max length, for dimensions this represents the min/max pixel count 305 double component_min, component_max; ///< For string this represents the unicode range for chars, 0-127 limits to ASCII 306 int is_range; ///< if set to 1 the struct encodes a range, if set to 0 a single value 307 } AVOptionRange; 308 309 /** 310 * List of AVOptionRange structs 311 */ 312 typedef struct AVOptionRanges { 313 AVOptionRange **range; 314 int nb_ranges; 315 } AVOptionRanges; 316 317 318 #if FF_API_FIND_OPT 319 /** 320 * Look for an option in obj. Look only for the options which 321 * have the flags set as specified in mask and flags (that is, 322 * for which it is the case that opt->flags & mask == flags). 323 * 324 * @param[in] obj a pointer to a struct whose first element is a 325 * pointer to an AVClass 326 * @param[in] name the name of the option to look for 327 * @param[in] unit the unit of the option to look for, or any if NULL 328 * @return a pointer to the option found, or NULL if no option 329 * has been found 330 * 331 * @deprecated use av_opt_find. 332 */ 333 attribute_deprecated 334 const AVOption *av_find_opt(void *obj, const char *name, const char *unit, int mask, int flags); 335 #endif 336 337 #if FF_API_OLD_AVOPTIONS 338 /** 339 * Set the field of obj with the given name to value. 340 * 341 * @param[in] obj A struct whose first element is a pointer to an 342 * AVClass. 343 * @param[in] name the name of the field to set 344 * @param[in] val The value to set. If the field is not of a string 345 * type, then the given string is parsed. 346 * SI postfixes and some named scalars are supported. 347 * If the field is of a numeric type, it has to be a numeric or named 348 * scalar. Behavior with more than one scalar and +- infix operators 349 * is undefined. 350 * If the field is of a flags type, it has to be a sequence of numeric 351 * scalars or named flags separated by '+' or '-'. Prefixing a flag 352 * with '+' causes it to be set without affecting the other flags; 353 * similarly, '-' unsets a flag. 354 * @param[out] o_out if non-NULL put here a pointer to the AVOption 355 * found 356 * @param alloc this parameter is currently ignored 357 * @return 0 if the value has been set, or an AVERROR code in case of 358 * error: 359 * AVERROR_OPTION_NOT_FOUND if no matching option exists 360 * AVERROR(ERANGE) if the value is out of range 361 * AVERROR(EINVAL) if the value is not valid 362 * @deprecated use av_opt_set() 363 */ 364 attribute_deprecated 365 int av_set_string3(void *obj, const char *name, const char *val, int alloc, const AVOption **o_out); 366 367 attribute_deprecated const AVOption *av_set_double(void *obj, const char *name, double n); 368 attribute_deprecated const AVOption *av_set_q(void *obj, const char *name, AVRational n); 369 attribute_deprecated const AVOption *av_set_int(void *obj, const char *name, int64_t n); 370 371 double av_get_double(void *obj, const char *name, const AVOption **o_out); 372 AVRational av_get_q(void *obj, const char *name, const AVOption **o_out); 373 int64_t av_get_int(void *obj, const char *name, const AVOption **o_out); 374 attribute_deprecated const char *av_get_string(void *obj, const char *name, const AVOption **o_out, char *buf, int buf_len); 375 attribute_deprecated const AVOption *av_next_option(void *obj, const AVOption *last); 376 #endif 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 #if FF_API_OLD_AVOPTIONS 397 attribute_deprecated 398 void av_opt_set_defaults2(void *s, int mask, int flags); 399 #endif 400 401 /** 402 * Parse the key/value pairs list in opts. For each key/value pair 403 * found, stores the value in the field in ctx that is named like the 404 * key. ctx must be an AVClass context, storing is done using 405 * AVOptions. 406 * 407 * @param opts options string to parse, may be NULL 408 * @param key_val_sep a 0-terminated list of characters used to 409 * separate key from value 410 * @param pairs_sep a 0-terminated list of characters used to separate 411 * two pairs from each other 412 * @return the number of successfully set key/value pairs, or a negative 413 * value corresponding to an AVERROR code in case of error: 414 * AVERROR(EINVAL) if opts cannot be parsed, 415 * the error code issued by av_set_string3() if a key/value pair 416 * cannot be set 417 */ 418 int av_set_options_string(void *ctx, const char *opts, 419 const char *key_val_sep, const char *pairs_sep); 420 421 /** 422 * Parse the key-value pairs list in opts. For each key=value pair found, 423 * set the value of the corresponding option in ctx. 424 * 425 * @param ctx the AVClass object to set options on 426 * @param opts the options string, key-value pairs separated by a 427 * delimiter 428 * @param shorthand a NULL-terminated array of options names for shorthand 429 * notation: if the first field in opts has no key part, 430 * the key is taken from the first element of shorthand; 431 * then again for the second, etc., until either opts is 432 * finished, shorthand is finished or a named option is 433 * found; after that, all options must be named 434 * @param key_val_sep a 0-terminated list of characters used to separate 435 * key from value, for example '=' 436 * @param pairs_sep a 0-terminated list of characters used to separate 437 * two pairs from each other, for example ':' or ',' 438 * @return the number of successfully set key=value pairs, or a negative 439 * value corresponding to an AVERROR code in case of error: 440 * AVERROR(EINVAL) if opts cannot be parsed, 441 * the error code issued by av_set_string3() if a key/value pair 442 * cannot be set 443 * 444 * Options names must use only the following characters: a-z A-Z 0-9 - . / _ 445 * Separators must use characters distinct from option names and from each 446 * other. 447 */ 448 int av_opt_set_from_string(void *ctx, const char *opts, 449 const char *const *shorthand, 450 const char *key_val_sep, const char *pairs_sep); 451 /** 452 * Free all string and binary options in obj. 453 */ 454 void av_opt_free(void *obj); 455 456 /** 457 * Check whether a particular flag is set in a flags field. 458 * 459 * @param field_name the name of the flag field option 460 * @param flag_name the name of the flag to check 461 * @return non-zero if the flag is set, zero if the flag isn't set, 462 * isn't of the right type, or the flags field doesn't exist. 463 */ 464 int av_opt_flag_is_set(void *obj, const char *field_name, const char *flag_name); 465 466 /** 467 * Set all the options from a given dictionary on an object. 468 * 469 * @param obj a struct whose first element is a pointer to AVClass 470 * @param options options to process. This dictionary will be freed and replaced 471 * by a new one containing all options not found in obj. 472 * Of course this new dictionary needs to be freed by caller 473 * with av_dict_free(). 474 * 475 * @return 0 on success, a negative AVERROR if some option was found in obj, 476 * but could not be set. 477 * 478 * @see av_dict_copy() 479 */ 480 int av_opt_set_dict(void *obj, struct AVDictionary **options); 481 482 /** 483 * Extract a key-value pair from the beginning of a string. 484 * 485 * @param ropts pointer to the options string, will be updated to 486 * point to the rest of the string (one of the pairs_sep 487 * or the final NUL) 488 * @param key_val_sep a 0-terminated list of characters used to separate 489 * key from value, for example '=' 490 * @param pairs_sep a 0-terminated list of characters used to separate 491 * two pairs from each other, for example ':' or ',' 492 * @param flags flags; see the AV_OPT_FLAG_* values below 493 * @param rkey parsed key; must be freed using av_free() 494 * @param rval parsed value; must be freed using av_free() 495 * 496 * @return >=0 for success, or a negative value corresponding to an 497 * AVERROR code in case of error; in particular: 498 * AVERROR(EINVAL) if no key is present 499 * 500 */ 501 int av_opt_get_key_value(const char **ropts, 502 const char *key_val_sep, const char *pairs_sep, 503 unsigned flags, 504 char **rkey, char **rval); 505 506 enum { 507 508 /** 509 * Accept to parse a value without a key; the key will then be returned 510 * as NULL. 511 */ 512 AV_OPT_FLAG_IMPLICIT_KEY = 1, 513 }; 514 515 /** 516 * @defgroup opt_eval_funcs Evaluating option strings 517 * @{ 518 * This group of functions can be used to evaluate option strings 519 * and get numbers out of them. They do the same thing as av_opt_set(), 520 * except the result is written into the caller-supplied pointer. 521 * 522 * @param obj a struct whose first element is a pointer to AVClass. 523 * @param o an option for which the string is to be evaluated. 524 * @param val string to be evaluated. 525 * @param *_out value of the string will be written here. 526 * 527 * @return 0 on success, a negative number on failure. 528 */ 529 int av_opt_eval_flags (void *obj, const AVOption *o, const char *val, int *flags_out); 530 int av_opt_eval_int (void *obj, const AVOption *o, const char *val, int *int_out); 531 int av_opt_eval_int64 (void *obj, const AVOption *o, const char *val, int64_t *int64_out); 532 int av_opt_eval_float (void *obj, const AVOption *o, const char *val, float *float_out); 533 int av_opt_eval_double(void *obj, const AVOption *o, const char *val, double *double_out); 534 int av_opt_eval_q (void *obj, const AVOption *o, const char *val, AVRational *q_out); 535 /** 536 * @} 537 */ 538 539 #define AV_OPT_SEARCH_CHILDREN 0x0001 /**< Search in possible children of the 540 given object first. */ 541 /** 542 * The obj passed to av_opt_find() is fake -- only a double pointer to AVClass 543 * instead of a required pointer to a struct containing AVClass. This is 544 * useful for searching for options without needing to allocate the corresponding 545 * object. 546 */ 547 #define AV_OPT_SEARCH_FAKE_OBJ 0x0002 548 549 /** 550 * Look for an option in an object. Consider only options which 551 * have all the specified flags set. 552 * 553 * @param[in] obj A pointer to a struct whose first element is a 554 * pointer to an AVClass. 555 * Alternatively a double pointer to an AVClass, if 556 * AV_OPT_SEARCH_FAKE_OBJ search flag is set. 557 * @param[in] name The name of the option to look for. 558 * @param[in] unit When searching for named constants, name of the unit 559 * it belongs to. 560 * @param opt_flags Find only options with all the specified flags set (AV_OPT_FLAG). 561 * @param search_flags A combination of AV_OPT_SEARCH_*. 562 * 563 * @return A pointer to the option found, or NULL if no option 564 * was found. 565 * 566 * @note Options found with AV_OPT_SEARCH_CHILDREN flag may not be settable 567 * directly with av_set_string3(). Use special calls which take an options 568 * AVDictionary (e.g. avformat_open_input()) to set options found with this 569 * flag. 570 */ 571 const AVOption *av_opt_find(void *obj, const char *name, const char *unit, 572 int opt_flags, int search_flags); 573 574 /** 575 * Look for an option in an object. Consider only options which 576 * have all the specified flags set. 577 * 578 * @param[in] obj A pointer to a struct whose first element is a 579 * pointer to an AVClass. 580 * Alternatively a double pointer to an AVClass, if 581 * AV_OPT_SEARCH_FAKE_OBJ search flag is set. 582 * @param[in] name The name of the option to look for. 583 * @param[in] unit When searching for named constants, name of the unit 584 * it belongs to. 585 * @param opt_flags Find only options with all the specified flags set (AV_OPT_FLAG). 586 * @param search_flags A combination of AV_OPT_SEARCH_*. 587 * @param[out] target_obj if non-NULL, an object to which the option belongs will be 588 * written here. It may be different from obj if AV_OPT_SEARCH_CHILDREN is present 589 * in search_flags. This parameter is ignored if search_flags contain 590 * AV_OPT_SEARCH_FAKE_OBJ. 591 * 592 * @return A pointer to the option found, or NULL if no option 593 * was found. 594 */ 595 const AVOption *av_opt_find2(void *obj, const char *name, const char *unit, 596 int opt_flags, int search_flags, void **target_obj); 597 598 /** 599 * Iterate over all AVOptions belonging to obj. 600 * 601 * @param obj an AVOptions-enabled struct or a double pointer to an 602 * AVClass describing it. 603 * @param prev result of the previous call to av_opt_next() on this object 604 * or NULL 605 * @return next AVOption or NULL 606 */ 607 const AVOption *av_opt_next(void *obj, const AVOption *prev); 608 609 /** 610 * Iterate over AVOptions-enabled children of obj. 611 * 612 * @param prev result of a previous call to this function or NULL 613 * @return next AVOptions-enabled child or NULL 614 */ 615 void *av_opt_child_next(void *obj, void *prev); 616 617 /** 618 * Iterate over potential AVOptions-enabled children of parent. 619 * 620 * @param prev result of a previous call to this function or NULL 621 * @return AVClass corresponding to next potential child or NULL 622 */ 623 const AVClass *av_opt_child_class_next(const AVClass *parent, const AVClass *prev); 624 625 /** 626 * @defgroup opt_set_funcs Option setting functions 627 * @{ 628 * Those functions set the field of obj with the given name to value. 629 * 630 * @param[in] obj A struct whose first element is a pointer to an AVClass. 631 * @param[in] name the name of the field to set 632 * @param[in] val The value to set. In case of av_opt_set() if the field is not 633 * of a string type, then the given string is parsed. 634 * SI postfixes and some named scalars are supported. 635 * If the field is of a numeric type, it has to be a numeric or named 636 * scalar. Behavior with more than one scalar and +- infix operators 637 * is undefined. 638 * If the field is of a flags type, it has to be a sequence of numeric 639 * scalars or named flags separated by '+' or '-'. Prefixing a flag 640 * with '+' causes it to be set without affecting the other flags; 641 * similarly, '-' unsets a flag. 642 * @param search_flags flags passed to av_opt_find2. I.e. if AV_OPT_SEARCH_CHILDREN 643 * is passed here, then the option may be set on a child of obj. 644 * 645 * @return 0 if the value has been set, or an AVERROR code in case of 646 * error: 647 * AVERROR_OPTION_NOT_FOUND if no matching option exists 648 * AVERROR(ERANGE) if the value is out of range 649 * AVERROR(EINVAL) if the value is not valid 650 */ 651 int av_opt_set (void *obj, const char *name, const char *val, int search_flags); 652 int av_opt_set_int (void *obj, const char *name, int64_t val, int search_flags); 653 int av_opt_set_double(void *obj, const char *name, double val, int search_flags); 654 int av_opt_set_q (void *obj, const char *name, AVRational val, int search_flags); 655 int av_opt_set_bin (void *obj, const char *name, const uint8_t *val, int size, int search_flags); 656 int av_opt_set_image_size(void *obj, const char *name, int w, int h, int search_flags); 657 int av_opt_set_pixel_fmt (void *obj, const char *name, enum AVPixelFormat fmt, int search_flags); 658 int av_opt_set_sample_fmt(void *obj, const char *name, enum AVSampleFormat fmt, int search_flags); 659 int av_opt_set_video_rate(void *obj, const char *name, AVRational val, int search_flags); 660 661 /** 662 * Set a binary option to an integer list. 663 * 664 * @param obj AVClass object to set options on 665 * @param name name of the binary option 666 * @param val pointer to an integer list (must have the correct type with 667 * regard to the contents of the list) 668 * @param term list terminator (usually 0 or -1) 669 * @param flags search flags 670 */ 671 #define av_opt_set_int_list(obj, name, val, term, flags) \ 672 (av_int_list_length(val, term) > INT_MAX / sizeof(*(val)) ? \ 673 AVERROR(EINVAL) : \ 674 av_opt_set_bin(obj, name, (const uint8_t *)(val), \ 675 av_int_list_length(val, term) * sizeof(*(val)), flags)) 676 /** 677 * @} 678 */ 679 680 /** 681 * @defgroup opt_get_funcs Option getting functions 682 * @{ 683 * Those functions get a value of the option with the given name from an object. 684 * 685 * @param[in] obj a struct whose first element is a pointer to an AVClass. 686 * @param[in] name name of the option to get. 687 * @param[in] search_flags flags passed to av_opt_find2. I.e. if AV_OPT_SEARCH_CHILDREN 688 * is passed here, then the option may be found in a child of obj. 689 * @param[out] out_val value of the option will be written here 690 * @return 0 on success, a negative error code otherwise 691 */ 692 /** 693 * @note the returned string will av_malloc()ed and must be av_free()ed by the caller 694 */ 695 int av_opt_get (void *obj, const char *name, int search_flags, uint8_t **out_val); 696 int av_opt_get_int (void *obj, const char *name, int search_flags, int64_t *out_val); 697 int av_opt_get_double(void *obj, const char *name, int search_flags, double *out_val); 698 int av_opt_get_q (void *obj, const char *name, int search_flags, AVRational *out_val); 699 int av_opt_get_image_size(void *obj, const char *name, int search_flags, int *w_out, int *h_out); 700 int av_opt_get_pixel_fmt (void *obj, const char *name, int search_flags, enum AVPixelFormat *out_fmt); 701 int av_opt_get_sample_fmt(void *obj, const char *name, int search_flags, enum AVSampleFormat *out_fmt); 702 int av_opt_get_video_rate(void *obj, const char *name, int search_flags, AVRational *out_val); 703 /** 704 * @} 705 */ 706 /** 707 * Gets a pointer to the requested field in a struct. 708 * This function allows accessing a struct even when its fields are moved or 709 * renamed since the application making the access has been compiled, 710 * 711 * @returns a pointer to the field, it can be cast to the correct type and read 712 * or written to. 713 */ 714 void *av_opt_ptr(const AVClass *avclass, void *obj, const char *name); 715 716 /** 717 * Free an AVOptionRanges struct and set it to NULL. 718 */ 719 void av_opt_freep_ranges(AVOptionRanges **ranges); 720 721 /** 722 * Get a list of allowed ranges for the given option. 723 * 724 * The returned list may depend on other fields in obj like for example profile. 725 * 726 * @param flags is a bitmask of flags, undefined flags should not be set and should be ignored 727 * AV_OPT_SEARCH_FAKE_OBJ indicates that the obj is a double pointer to a AVClass instead of a full instance 728 * 729 * The result must be freed with av_opt_freep_ranges. 730 * 731 * @return >= 0 on success, a negative errro code otherwise 732 */ 733 int av_opt_query_ranges(AVOptionRanges **, void *obj, const char *key, int flags); 734 735 /** 736 * Get a default list of allowed ranges for the given option. 737 * 738 * This list is constructed without using the AVClass.query_ranges() callback 739 * and can be used as fallback from within the callback. 740 * 741 * @param flags is a bitmask of flags, undefined flags should not be set and should be ignored 742 * AV_OPT_SEARCH_FAKE_OBJ indicates that the obj is a double pointer to a AVClass instead of a full instance 743 * 744 * The result must be freed with av_opt_free_ranges. 745 * 746 * @return >= 0 on success, a negative errro code otherwise 747 */ 748 int av_opt_query_ranges_default(AVOptionRanges **, void *obj, const char *key, int flags); 749 750 /** 751 * @} 752 */ 753 754 #endif /* AVUTIL_OPT_H */ 755