libavcodec/opt.h

   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 AVCODEC_OPT_H
  23 #define AVCODEC_OPT_H
  24
  25 /**
  26  * @file libavcodec/opt.h
  27  * AVOptions
  28  */
  29
  30 #include "libavutil/rational.h"
  31 #include "avcodec.h"
  32
  33 enum AVOptionType{
  34     FF_OPT_TYPE_FLAGS,
  35     FF_OPT_TYPE_INT,
  36     FF_OPT_TYPE_INT64,
  37     FF_OPT_TYPE_DOUBLE,
  38     FF_OPT_TYPE_FLOAT,
  39     FF_OPT_TYPE_STRING,
  40     FF_OPT_TYPE_RATIONAL,
  41     FF_OPT_TYPE_BINARY,  ///< offset must point to a pointer immediately followed by an int for the length
  42     FF_OPT_TYPE_CONST=128,
  43 };
  44
  45 /**
  46  * AVOption
  47  */
  48 typedef struct AVOption {
  49     const char *name;
  50
  51     /**
  52      * short English help text
  53      * @todo What about other languages?
  54      */
  55     const char *help;
  56
  57     /**
  58      * The offset relative to the context structure where the option
  59      * value is stored. It should be 0 for named constants.
  60      */
  61     int offset;
  62     enum AVOptionType type;
  63
  64     /**
  65      * the default value for scalar options
  66      */
  67     double default_val;
  68     double min;                 ///< minimum valid value for the option
  69     double max;                 ///< maximum valid value for the option
  70
  71     int flags;
  72 #define AV_OPT_FLAG_ENCODING_PARAM  1   ///< a generic parameter which can be set by the user for muxing or encoding
  73 #define AV_OPT_FLAG_DECODING_PARAM  2   ///< a generic parameter which can be set by the user for demuxing or decoding
  74 #define AV_OPT_FLAG_METADATA        4   ///< some data extracted or inserted into the file like title, comment, ...
  75 #define AV_OPT_FLAG_AUDIO_PARAM     8
  76 #define AV_OPT_FLAG_VIDEO_PARAM     16
  77 #define AV_OPT_FLAG_SUBTITLE_PARAM  32
  78 //FIXME think about enc-audio, ... style flags
  79
  80     /**
  81      * The logical unit to which the option belongs. Non-constant
  82      * options and corresponding named constants share the same
  83      * unit. May be NULL.
  84      */
  85     const char *unit;
  86 } AVOption;
  87
  88
  89 /**
  90  * Looks for an option in obj. Looks only for the options which
  91  * have the flags set as specified in mask and flags (that is,
  92  * for which it is the case that opt->flags & mask == flags).
  93  *
  94  * @param[in] obj a pointer to a struct whose first element is a
  95  * pointer to an AVClass
  96  * @param[in] name the name of the option to look for
  97  * @param[in] unit the unit of the option to look for, or any if NULL
  98  * @return a pointer to the option found, or NULL if no option
  99  * has been found
 100  */
 101 const AVOption *av_find_opt(void *obj, const char *name, const char *unit, int mask, int flags);
 102
 103 #if LIBAVCODEC_VERSION_MAJOR < 53
 104 /**
 105  * @see av_set_string2()
 106  */
 107 attribute_deprecated const AVOption *av_set_string(void *obj, const char *name, const char *val);
 108
 109 /**
 110  * @return a pointer to the AVOption corresponding to the field set or
 111  * NULL if no matching AVOption exists, or if the value val is not
 112  * valid
 113  * @see av_set_string3()
 114  */
 115 attribute_deprecated const AVOption *av_set_string2(void *obj, const char *name, const char *val, int alloc);
 116 #endif
 117
 118 /**
 119  * Sets the field of obj with the given name to value.
 120  *
 121  * @param[in] obj A struct whose first element is a pointer to an
 122  * AVClass.
 123  * @param[in] name the name of the field to set
 124  * @param[in] val The value to set. If the field is not of a string
 125  * type, then the given string is parsed.
 126  * SI postfixes and some named scalars are supported.
 127  * If the field is of a numeric type, it has to be a numeric or named
 128  * scalar. Behavior with more than one scalar and +- infix operators
 129  * is undefined.
 130  * If the field is of a flags type, it has to be a sequence of numeric
 131  * scalars or named flags separated by '+' or '-'. Prefixing a flag
 132  * with '+' causes it to be set without affecting the other flags;
 133  * similarly, '-' unsets a flag.
 134  * @param[out] o_out if non-NULL put here a pointer to the AVOption
 135  * found
 136  * @param alloc when 1 then the old value will be av_freed() and the
 137  *                     new av_strduped()
 138  *              when 0 then no av_free() nor av_strdup() will be used
 139  * @return 0 if the value has been set, or an AVERROR code in case of
 140  * error:
 141  * AVERROR(ENOENT) if no matching option exists
 142  * AVERROR(ERANGE) if the value is out of range
 143  * AVERROR(EINVAL) if the value is not valid
 144  */
 145 int av_set_string3(void *obj, const char *name, const char *val, int alloc, const AVOption **o_out);
 146
 147 const AVOption *av_set_double(void *obj, const char *name, double n);
 148 const AVOption *av_set_q(void *obj, const char *name, AVRational n);
 149 const AVOption *av_set_int(void *obj, const char *name, int64_t n);
 150 double av_get_double(void *obj, const char *name, const AVOption **o_out);
 151 AVRational av_get_q(void *obj, const char *name, const AVOption **o_out);
 152 int64_t av_get_int(void *obj, const char *name, const AVOption **o_out);
 153 const char *av_get_string(void *obj, const char *name, const AVOption **o_out, char *buf, int buf_len);
 154 const AVOption *av_next_option(void *obj, const AVOption *last);
 155 int av_opt_show(void *obj, void *av_log_obj);
 156 void av_opt_set_defaults(void *s);
 157 void av_opt_set_defaults2(void *s, int mask, int flags);
 158
 159 #endif /* AVCODEC_OPT_H */