FFmpeg/libavutil/opt.h

/*
 * 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"

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,
#if FF_API_OLD_AVOPTIONS
    FF_OPT_TYPE_FLAGS = 0,
    FF_OPT_TYPE_INT,
    FF_OPT_TYPE_INT64,
    FF_OPT_TYPE_DOUBLE,
    FF_OPT_TYPE_FLOAT,
    FF_OPT_TYPE_STRING,
    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
};

/**
 * 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 {
        double dbl;
        const char *str;
        /* TODO those are unused now */
        int64_t i64;
        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;

#if FF_API_FIND_OPT
/**
 * Look for an option in obj. Look only for the options which
 * have the flags set as specified in mask and flags (that is,
 * for which it is the case that opt->flags & mask == flags).
 *
 * @param[in] obj a pointer to a struct whose first element is a
 * pointer to an AVClass
 * @param[in] name the name of the option to look for
 * @param[in] unit the unit of the option to look for, or any if NULL
 * @return a pointer to the option found, or NULL if no option
 * has been found
 *
 * @deprecated use av_opt_find.
 */
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.
 *
 * @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. 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[out] o_out if non-NULL put here a pointer to the AVOption
 * found
 * @param alloc this parameter is currently ignored
 * @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
 * @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);

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.
 *
 * @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);

#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
 * 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);
/**
 * @}
 */

/**
 * @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 */