X-Git-Url: https://git.sesse.net/?a=blobdiff_plain;f=libavutil%2Fopt.h;h=19549408e2e3df94e7059b24a25e367211920c60;hb=68b94f8bc3a54735c360c6e72a3698fed8aba10b;hp=30aa54f5b6c021633d8c1c9249dcc1bd07d8d80c;hpb=dc59ec5e79d813228e3dfbc8942a5fe424b399a0;p=ffmpeg diff --git a/libavutil/opt.h b/libavutil/opt.h index 30aa54f5b6c..19549408e2e 100644 --- a/libavutil/opt.h +++ b/libavutil/opt.h @@ -30,9 +30,203 @@ #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, { -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, { 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, { 0 }, INT_MIN, INT_MAX, "test_unit" }, + * { "flag1", "This is a flag with value 16", 0, AV_OPT_TYPE_CONST, { 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{ - FF_OPT_TYPE_FLAGS, + 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, +#if FF_API_OLD_AVOPTIONS + FF_OPT_TYPE_FLAGS = 0, FF_OPT_TYPE_INT, FF_OPT_TYPE_INT64, FF_OPT_TYPE_DOUBLE, @@ -41,6 +235,7 @@ enum AVOptionType{ FF_OPT_TYPE_RATIONAL, FF_OPT_TYPE_BINARY, ///< offset must point to a pointer immediately followed by an int for the length FF_OPT_TYPE_CONST=128, +#endif }; /** @@ -111,6 +306,7 @@ attribute_deprecated const AVOption *av_find_opt(void *obj, const char *name, const char *unit, int mask, int flags); #endif +#if FF_API_OLD_AVOPTIONS /** * Set the field of obj with the given name to value. * @@ -129,25 +325,27 @@ const AVOption *av_find_opt(void *obj, const char *name, const char *unit, int m * similarly, '-' unsets a flag. * @param[out] o_out if non-NULL put here a pointer to the AVOption * found - * @param alloc when 1 then the old value will be av_freed() and the - * new av_strduped() - * when 0 then no av_free() nor av_strdup() will be used + * @param alloc this parameter is currently ignored * @return 0 if the value has been set, or an AVERROR code in case of * error: - * AVERROR(ENOENT) if no matching option exists + * 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 + * @deprecated use av_opt_set() */ +attribute_deprecated int av_set_string3(void *obj, const char *name, const char *val, int alloc, const AVOption **o_out); -const AVOption *av_set_double(void *obj, const char *name, double n); -const AVOption *av_set_q(void *obj, const char *name, AVRational n); -const AVOption *av_set_int(void *obj, const char *name, int64_t n); -double av_get_double(void *obj, const char *name, const AVOption **o_out); -AVRational av_get_q(void *obj, const char *name, const AVOption **o_out); -int64_t av_get_int(void *obj, const char *name, const AVOption **o_out); -const char *av_get_string(void *obj, const char *name, const AVOption **o_out, char *buf, int buf_len); -const AVOption *av_next_option(void *obj, const AVOption *last); +attribute_deprecated const AVOption *av_set_double(void *obj, const char *name, double n); +attribute_deprecated const AVOption *av_set_q(void *obj, const char *name, AVRational n); +attribute_deprecated const AVOption *av_set_int(void *obj, const char *name, int64_t n); + +attribute_deprecated double av_get_double(void *obj, const char *name, const AVOption **o_out); +attribute_deprecated AVRational av_get_q(void *obj, const char *name, const AVOption **o_out); +attribute_deprecated int64_t av_get_int(void *obj, const char *name, const AVOption **o_out); +attribute_deprecated const char *av_get_string(void *obj, const char *name, const AVOption **o_out, char *buf, int buf_len); +attribute_deprecated const AVOption *av_next_option(void *obj, const AVOption *last); +#endif /** * Show the obj options. @@ -160,8 +358,17 @@ const AVOption *av_next_option(void *obj, const AVOption *last); */ 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); + +#if FF_API_OLD_AVOPTIONS +attribute_deprecated void av_opt_set_defaults2(void *s, int mask, int flags); +#endif /** * Parse the key/value pairs list in opts. For each key/value pair @@ -213,8 +420,39 @@ int av_opt_flag_is_set(void *obj, const char *field_name, const char *flag_name) */ 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 @@ -222,6 +460,8 @@ int av_opt_set_dict(void *obj, struct AVDictionary **options); * * @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. @@ -239,4 +479,113 @@ int av_opt_set_dict(void *obj, struct AVDictionary **options); 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); +/** + * @} + */ + +/** + * @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 */