| /* |
| * AVOptions |
| * copyright (c) 2005 Michael Niedermayer <michaelni@gmx.at> |
| * |
| * This file is part of Libav. |
| * |
| * Libav is free software; you can redistribute it and/or |
| * modify it under the terms of the GNU Lesser General Public |
| * License as published by the Free Software Foundation; either |
| * version 2.1 of the License, or (at your option) any later version. |
| * |
| * Libav is distributed in the hope that it will be useful, |
| * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
| * Lesser General Public License for more details. |
| * |
| * You should have received a copy of the GNU Lesser General Public |
| * License along with Libav; if not, write to the Free Software |
| * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA |
| */ |
| |
| #ifndef AVUTIL_OPT_H |
| #define AVUTIL_OPT_H |
| |
| /** |
| * @file |
| * AVOptions |
| */ |
| |
| #include "rational.h" |
| #include "avutil.h" |
| #include "dict.h" |
| #include "log.h" |
| |
| /** |
| * @defgroup avoptions AVOptions |
| * @ingroup lavu_data |
| * @{ |
| * AVOptions provide a generic system to declare options on arbitrary structs |
| * ("objects"). An option can have a help text, a type and a range of possible |
| * values. Options may then be enumerated, read and written to. |
| * |
| * @section avoptions_implement Implementing AVOptions |
| * This section describes how to add AVOptions capabilities to a struct. |
| * |
| * All AVOptions-related information is stored in an AVClass. Therefore |
| * the first member of the struct must be a pointer to an AVClass describing it. |
| * The option field of the AVClass must be set to a NULL-terminated static array |
| * of AVOptions. Each AVOption must have a non-empty name, a type, a default |
| * value and for number-type AVOptions also a range of allowed values. It must |
| * also declare an offset in bytes from the start of the struct, where the field |
| * associated with this AVOption is located. Other fields in the AVOption struct |
| * should also be set when applicable, but are not required. |
| * |
| * The following example illustrates an AVOptions-enabled struct: |
| * @code |
| * typedef struct test_struct { |
| * AVClass *class; |
| * int int_opt; |
| * char *str_opt; |
| * uint8_t *bin_opt; |
| * int bin_len; |
| * } test_struct; |
| * |
| * static const AVOption options[] = { |
| * { "test_int", "This is a test option of int type.", offsetof(test_struct, int_opt), |
| * AV_OPT_TYPE_INT, { .i64 = -1 }, INT_MIN, INT_MAX }, |
| * { "test_str", "This is a test option of string type.", offsetof(test_struct, str_opt), |
| * AV_OPT_TYPE_STRING }, |
| * { "test_bin", "This is a test option of binary type.", offsetof(test_struct, bin_opt), |
| * AV_OPT_TYPE_BINARY }, |
| * { NULL }, |
| * }; |
| * |
| * static const AVClass test_class = { |
| * .class_name = "test class", |
| * .item_name = av_default_item_name, |
| * .option = options, |
| * .version = LIBAVUTIL_VERSION_INT, |
| * }; |
| * @endcode |
| * |
| * Next, when allocating your struct, you must ensure that the AVClass pointer |
| * is set to the correct value. Then, av_opt_set_defaults() must be called to |
| * initialize defaults. After that the struct is ready to be used with the |
| * AVOptions API. |
| * |
| * When cleaning up, you may use the av_opt_free() function to automatically |
| * free all the allocated string and binary options. |
| * |
| * Continuing with the above example: |
| * |
| * @code |
| * test_struct *alloc_test_struct(void) |
| * { |
| * test_struct *ret = av_malloc(sizeof(*ret)); |
| * ret->class = &test_class; |
| * av_opt_set_defaults(ret); |
| * return ret; |
| * } |
| * void free_test_struct(test_struct **foo) |
| * { |
| * av_opt_free(*foo); |
| * av_freep(foo); |
| * } |
| * @endcode |
| * |
| * @subsection avoptions_implement_nesting Nesting |
| * It may happen that an AVOptions-enabled struct contains another |
| * AVOptions-enabled struct as a member (e.g. AVCodecContext in |
| * libavcodec exports generic options, while its priv_data field exports |
| * codec-specific options). In such a case, it is possible to set up the |
| * parent struct to export a child's options. To do that, simply |
| * implement AVClass.child_next() and AVClass.child_class_next() in the |
| * parent struct's AVClass. |
| * Assuming that the test_struct from above now also contains a |
| * child_struct field: |
| * |
| * @code |
| * typedef struct child_struct { |
| * AVClass *class; |
| * int flags_opt; |
| * } child_struct; |
| * static const AVOption child_opts[] = { |
| * { "test_flags", "This is a test option of flags type.", |
| * offsetof(child_struct, flags_opt), AV_OPT_TYPE_FLAGS, { .i64 = 0 }, INT_MIN, INT_MAX }, |
| * { NULL }, |
| * }; |
| * static const AVClass child_class = { |
| * .class_name = "child class", |
| * .item_name = av_default_item_name, |
| * .option = child_opts, |
| * .version = LIBAVUTIL_VERSION_INT, |
| * }; |
| * |
| * void *child_next(void *obj, void *prev) |
| * { |
| * test_struct *t = obj; |
| * if (!prev && t->child_struct) |
| * return t->child_struct; |
| * return NULL |
| * } |
| * const AVClass child_class_next(const AVClass *prev) |
| * { |
| * return prev ? NULL : &child_class; |
| * } |
| * @endcode |
| * Putting child_next() and child_class_next() as defined above into |
| * test_class will now make child_struct's options accessible through |
| * test_struct (again, proper setup as described above needs to be done on |
| * child_struct right after it is created). |
| * |
| * From the above example it might not be clear why both child_next() |
| * and child_class_next() are needed. The distinction is that child_next() |
| * iterates over actually existing objects, while child_class_next() |
| * iterates over all possible child classes. E.g. if an AVCodecContext |
| * was initialized to use a codec which has private options, then its |
| * child_next() will return AVCodecContext.priv_data and finish |
| * iterating. OTOH child_class_next() on AVCodecContext.av_class will |
| * iterate over all available codecs with private options. |
| * |
| * @subsection avoptions_implement_named_constants Named constants |
| * It is possible to create named constants for options. Simply set the unit |
| * field of the option the constants should apply to to a string and |
| * create the constants themselves as options of type AV_OPT_TYPE_CONST |
| * with their unit field set to the same string. |
| * Their default_val field should contain the value of the named |
| * constant. |
| * For example, to add some named constants for the test_flags option |
| * above, put the following into the child_opts array: |
| * @code |
| * { "test_flags", "This is a test option of flags type.", |
| * offsetof(child_struct, flags_opt), AV_OPT_TYPE_FLAGS, { .i64 = 0 }, INT_MIN, INT_MAX, "test_unit" }, |
| * { "flag1", "This is a flag with value 16", 0, AV_OPT_TYPE_CONST, { .i64 = 16 }, 0, 0, "test_unit" }, |
| * @endcode |
| * |
| * @section avoptions_use Using AVOptions |
| * This section deals with accessing options in an AVOptions-enabled struct. |
| * Such structs in Libav are e.g. AVCodecContext in libavcodec or |
| * AVFormatContext in libavformat. |
| * |
| * @subsection avoptions_use_examine Examining AVOptions |
| * The basic functions for examining options are av_opt_next(), which iterates |
| * over all options defined for one object, and av_opt_find(), which searches |
| * for an option with the given name. |
| * |
| * The situation is more complicated with nesting. An AVOptions-enabled struct |
| * may have AVOptions-enabled children. Passing the AV_OPT_SEARCH_CHILDREN flag |
| * to av_opt_find() will make the function search children recursively. |
| * |
| * For enumerating there are basically two cases. The first is when you want to |
| * get all options that may potentially exist on the struct and its children |
| * (e.g. when constructing documentation). In that case you should call |
| * av_opt_child_class_next() recursively on the parent struct's AVClass. The |
| * second case is when you have an already initialized struct with all its |
| * children and you want to get all options that can be actually written or read |
| * from it. In that case you should call av_opt_child_next() recursively (and |
| * av_opt_next() on each result). |
| * |
| * @subsection avoptions_use_get_set Reading and writing AVOptions |
| * When setting options, you often have a string read directly from the |
| * user. In such a case, simply passing it to av_opt_set() is enough. For |
| * non-string type options, av_opt_set() will parse the string according to the |
| * option type. |
| * |
| * Similarly av_opt_get() will read any option type and convert it to a string |
| * which will be returned. Do not forget that the string is allocated, so you |
| * have to free it with av_free(). |
| * |
| * In some cases it may be more convenient to put all options into an |
| * AVDictionary and call av_opt_set_dict() on it. A specific case of this |
| * are the format/codec open functions in lavf/lavc which take a dictionary |
| * filled with option as a parameter. This allows to set some options |
| * that cannot be set otherwise, since e.g. the input file format is not known |
| * before the file is actually opened. |
| */ |
| |
| enum AVOptionType{ |
| AV_OPT_TYPE_FLAGS, |
| AV_OPT_TYPE_INT, |
| AV_OPT_TYPE_INT64, |
| AV_OPT_TYPE_DOUBLE, |
| AV_OPT_TYPE_FLOAT, |
| AV_OPT_TYPE_STRING, |
| AV_OPT_TYPE_RATIONAL, |
| AV_OPT_TYPE_BINARY, ///< offset must point to a pointer immediately followed by an int for the length |
| AV_OPT_TYPE_CONST = 128, |
| }; |
| |
| /** |
| * AVOption |
| */ |
| typedef struct AVOption { |
| const char *name; |
| |
| /** |
| * short English help text |
| * @todo What about other languages? |
| */ |
| const char *help; |
| |
| /** |
| * The offset relative to the context structure where the option |
| * value is stored. It should be 0 for named constants. |
| */ |
| int offset; |
| enum AVOptionType type; |
| |
| /** |
| * the default value for scalar options |
| */ |
| union { |
| int64_t i64; |
| double dbl; |
| const char *str; |
| /* TODO those are unused now */ |
| AVRational q; |
| } default_val; |
| double min; ///< minimum valid value for the option |
| double max; ///< maximum valid value for the option |
| |
| int flags; |
| #define AV_OPT_FLAG_ENCODING_PARAM 1 ///< a generic parameter which can be set by the user for muxing or encoding |
| #define AV_OPT_FLAG_DECODING_PARAM 2 ///< a generic parameter which can be set by the user for demuxing or decoding |
| #define AV_OPT_FLAG_METADATA 4 ///< some data extracted or inserted into the file like title, comment, ... |
| #define AV_OPT_FLAG_AUDIO_PARAM 8 |
| #define AV_OPT_FLAG_VIDEO_PARAM 16 |
| #define AV_OPT_FLAG_SUBTITLE_PARAM 32 |
| //FIXME think about enc-audio, ... style flags |
| |
| /** |
| * The logical unit to which the option belongs. Non-constant |
| * options and corresponding named constants share the same |
| * unit. May be NULL. |
| */ |
| const char *unit; |
| } AVOption; |
| |
| /** |
| * Show the obj options. |
| * |
| * @param req_flags requested flags for the options to show. Show only the |
| * options for which it is opt->flags & req_flags. |
| * @param rej_flags rejected flags for the options to show. Show only the |
| * options for which it is !(opt->flags & req_flags). |
| * @param av_log_obj log context to use for showing the options |
| */ |
| int av_opt_show2(void *obj, void *av_log_obj, int req_flags, int rej_flags); |
| |
| /** |
| * Set the values of all AVOption fields to their default values. |
| * |
| * @param s an AVOption-enabled struct (its first member must be a pointer to AVClass) |
| */ |
| void av_opt_set_defaults(void *s); |
| |
| /** |
| * Parse the key/value pairs list in opts. For each key/value pair |
| * found, stores the value in the field in ctx that is named like the |
| * key. ctx must be an AVClass context, storing is done using |
| * AVOptions. |
| * |
| * @param key_val_sep a 0-terminated list of characters used to |
| * separate key from value |
| * @param pairs_sep a 0-terminated list of characters used to separate |
| * two pairs from each other |
| * @return the number of successfully set key/value pairs, or a negative |
| * value corresponding to an AVERROR code in case of error: |
| * AVERROR(EINVAL) if opts cannot be parsed, |
| * the error code issued by av_set_string3() if a key/value pair |
| * cannot be set |
| */ |
| int av_set_options_string(void *ctx, const char *opts, |
| const char *key_val_sep, const char *pairs_sep); |
| |
| /** |
| * Free all string and binary options in obj. |
| */ |
| void av_opt_free(void *obj); |
| |
| /** |
| * Check whether a particular flag is set in a flags field. |
| * |
| * @param field_name the name of the flag field option |
| * @param flag_name the name of the flag to check |
| * @return non-zero if the flag is set, zero if the flag isn't set, |
| * isn't of the right type, or the flags field doesn't exist. |
| */ |
| int av_opt_flag_is_set(void *obj, const char *field_name, const char *flag_name); |
| |
| /* |
| * Set all the options from a given dictionary on an object. |
| * |
| * @param obj a struct whose first element is a pointer to AVClass |
| * @param options options to process. This dictionary will be freed and replaced |
| * by a new one containing all options not found in obj. |
| * Of course this new dictionary needs to be freed by caller |
| * with av_dict_free(). |
| * |
| * @return 0 on success, a negative AVERROR if some option was found in obj, |
| * but could not be set. |
| * |
| * @see av_dict_copy() |
| */ |
| int av_opt_set_dict(void *obj, struct AVDictionary **options); |
| |
| /** |
| * @defgroup opt_eval_funcs Evaluating option strings |
| * @{ |
| * This group of functions can be used to evaluate option strings |
| * and get numbers out of them. They do the same thing as av_opt_set(), |
| * except the result is written into the caller-supplied pointer. |
| * |
| * @param obj a struct whose first element is a pointer to AVClass. |
| * @param o an option for which the string is to be evaluated. |
| * @param val string to be evaluated. |
| * @param *_out value of the string will be written here. |
| * |
| * @return 0 on success, a negative number on failure. |
| */ |
| int av_opt_eval_flags (void *obj, const AVOption *o, const char *val, int *flags_out); |
| int av_opt_eval_int (void *obj, const AVOption *o, const char *val, int *int_out); |
| int av_opt_eval_int64 (void *obj, const AVOption *o, const char *val, int64_t *int64_out); |
| int av_opt_eval_float (void *obj, const AVOption *o, const char *val, float *float_out); |
| int av_opt_eval_double(void *obj, const AVOption *o, const char *val, double *double_out); |
| int av_opt_eval_q (void *obj, const AVOption *o, const char *val, AVRational *q_out); |
| /** |
| * @} |
| */ |
| |
| #define AV_OPT_SEARCH_CHILDREN 0x0001 /**< Search in possible children of the |
| given object first. */ |
| /** |
| * The obj passed to av_opt_find() is fake -- only a double pointer to AVClass |
| * instead of a required pointer to a struct containing AVClass. This is |
| * useful for searching for options without needing to allocate the corresponding |
| * object. |
| */ |
| #define AV_OPT_SEARCH_FAKE_OBJ 0x0002 |
| |
| /** |
| * Look for an option in an object. Consider only options which |
| * have all the specified flags set. |
| * |
| * @param[in] obj A pointer to a struct whose first element is a |
| * pointer to an AVClass. |
| * Alternatively a double pointer to an AVClass, if |
| * AV_OPT_SEARCH_FAKE_OBJ search flag is set. |
| * @param[in] name The name of the option to look for. |
| * @param[in] unit When searching for named constants, name of the unit |
| * it belongs to. |
| * @param opt_flags Find only options with all the specified flags set (AV_OPT_FLAG). |
| * @param search_flags A combination of AV_OPT_SEARCH_*. |
| * |
| * @return A pointer to the option found, or NULL if no option |
| * was found. |
| * |
| * @note Options found with AV_OPT_SEARCH_CHILDREN flag may not be settable |
| * directly with av_set_string3(). Use special calls which take an options |
| * AVDictionary (e.g. avformat_open_input()) to set options found with this |
| * flag. |
| */ |
| 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. Consider only options which |
| * have all the specified flags set. |
| * |
| * @param[in] obj A pointer to a struct whose first element is a |
| * pointer to an AVClass. |
| * Alternatively a double pointer to an AVClass, if |
| * AV_OPT_SEARCH_FAKE_OBJ search flag is set. |
| * @param[in] name The name of the option to look for. |
| * @param[in] unit When searching for named constants, name of the unit |
| * it belongs to. |
| * @param opt_flags Find only options with all the specified flags set (AV_OPT_FLAG). |
| * @param search_flags A combination of AV_OPT_SEARCH_*. |
| * @param[out] target_obj if non-NULL, an object to which the option belongs will be |
| * written here. It may be different from obj if AV_OPT_SEARCH_CHILDREN is present |
| * in search_flags. This parameter is ignored if search_flags contain |
| * AV_OPT_SEARCH_FAKE_OBJ. |
| * |
| * @return A pointer to the option found, or NULL if no option |
| * was found. |
| */ |
| const AVOption *av_opt_find2(void *obj, const char *name, const char *unit, |
| int opt_flags, int search_flags, void **target_obj); |
| |
| /** |
| * Iterate over all AVOptions belonging to obj. |
| * |
| * @param obj an AVOptions-enabled struct or a double pointer to an |
| * AVClass describing it. |
| * @param prev result of the previous call to av_opt_next() on this object |
| * or NULL |
| * @return next AVOption or NULL |
| */ |
| const AVOption *av_opt_next(void *obj, const AVOption *prev); |
| |
| /** |
| * Iterate over AVOptions-enabled children of obj. |
| * |
| * @param prev result of a previous call to this function or NULL |
| * @return next AVOptions-enabled child or NULL |
| */ |
| void *av_opt_child_next(void *obj, void *prev); |
| |
| /** |
| * Iterate over potential AVOptions-enabled children of parent. |
| * |
| * @param prev result of a previous call to this function or NULL |
| * @return AVClass corresponding to next potential child or NULL |
| */ |
| const AVClass *av_opt_child_class_next(const AVClass *parent, const AVClass *prev); |
| |
| /** |
| * @defgroup opt_set_funcs Option setting functions |
| * @{ |
| * Those functions set the field of obj with the given name to value. |
| * |
| * @param[in] obj A struct whose first element is a pointer to an AVClass. |
| * @param[in] name the name of the field to set |
| * @param[in] val The value to set. In case of av_opt_set() if the field is not |
| * of a string type, then the given string is parsed. |
| * SI postfixes and some named scalars are supported. |
| * If the field is of a numeric type, it has to be a numeric or named |
| * scalar. Behavior with more than one scalar and +- infix operators |
| * is undefined. |
| * If the field is of a flags type, it has to be a sequence of numeric |
| * scalars or named flags separated by '+' or '-'. Prefixing a flag |
| * with '+' causes it to be set without affecting the other flags; |
| * similarly, '-' unsets a flag. |
| * @param search_flags flags passed to av_opt_find2. I.e. if AV_OPT_SEARCH_CHILDREN |
| * is passed here, then the option may be set on a child of obj. |
| * |
| * @return 0 if the value has been set, or an AVERROR code in case of |
| * error: |
| * AVERROR_OPTION_NOT_FOUND if no matching option exists |
| * AVERROR(ERANGE) if the value is out of range |
| * AVERROR(EINVAL) if the value is not valid |
| */ |
| int av_opt_set (void *obj, const char *name, const char *val, int search_flags); |
| int av_opt_set_int (void *obj, const char *name, int64_t val, int search_flags); |
| int av_opt_set_double(void *obj, const char *name, double val, int search_flags); |
| int av_opt_set_q (void *obj, const char *name, AVRational val, int search_flags); |
| int av_opt_set_bin (void *obj, const char *name, const uint8_t *val, int size, int search_flags); |
| /** |
| * @} |
| */ |
| |
| /** |
| * @defgroup opt_get_funcs Option getting functions |
| * @{ |
| * Those functions get a value of the option with the given name from an object. |
| * |
| * @param[in] obj a struct whose first element is a pointer to an AVClass. |
| * @param[in] name name of the option to get. |
| * @param[in] search_flags flags passed to av_opt_find2. I.e. if AV_OPT_SEARCH_CHILDREN |
| * is passed here, then the option may be found in a child of obj. |
| * @param[out] out_val value of the option will be written here |
| * @return 0 on success, a negative error code otherwise |
| */ |
| /** |
| * @note the returned string will av_malloc()ed and must be av_free()ed by the caller |
| */ |
| int av_opt_get (void *obj, const char *name, int search_flags, uint8_t **out_val); |
| int av_opt_get_int (void *obj, const char *name, int search_flags, int64_t *out_val); |
| int av_opt_get_double(void *obj, const char *name, int search_flags, double *out_val); |
| int av_opt_get_q (void *obj, const char *name, int search_flags, AVRational *out_val); |
| /** |
| * @} |
| * @} |
| */ |
| |
| #endif /* AVUTIL_OPT_H */ |
