AVOption: add support for dictionary types.

In order to support metadata being set as an option, it's necessary to be able
to set dictionaries as values.
Signed-off-by: Anton Khirnov <anton@khirnov.net>

doc/APIchanges

@@ -13,6 +13,10 @@ libavutil:     2014-08-09
 
 API changes, most recent first:
 
+2014-xx-xx - xxxxxxx - lavu 54.02.0 - opt.h
+  Add av_opt_get_dict_val/set_dict_val with AV_OPT_TYPE_DICT to support
+  dictionary types being set as options.
+
 2014-xx-xx - xxxxxxx - lavf 56.01.0 - avformat.h
   Add AVFormatContext.event_flags and AVStream.event_flags for signaling to
   the user when events happen in the file/stream.

libavutil/opt.c

@@ -307,6 +307,24 @@ int av_opt_set_bin(void *obj, const char *name, const uint8_t *val, int len, int
     return 0;
 }
 
+int av_opt_set_dict_val(void *obj, const char *name, const AVDictionary *val, int search_flags)
+{
+    void *target_obj;
+    AVDictionary **dst;
+    const AVOption *o = av_opt_find2(obj, name, NULL, 0, search_flags, &target_obj);
+
+    if (!o || !target_obj)
+        return AVERROR_OPTION_NOT_FOUND;
+    if (o->flags & AV_OPT_FLAG_READONLY)
+        return AVERROR(EINVAL);
+
+    dst = (AVDictionary **)(((uint8_t *)target_obj) + o->offset);
+    av_dict_free(dst);
+    av_dict_copy(dst, val, 0);
+
+    return 0;
+}
+
 int av_opt_get(void *obj, const char *name, int search_flags, uint8_t **out_val)
 {
     void *dst, *target_obj;
@@ -410,6 +428,23 @@ int av_opt_get_q(void *obj, const char *name, int search_flags, AVRational *out_
     return 0;
 }
 
+int av_opt_get_dict_val(void *obj, const char *name, int search_flags, AVDictionary **out_val)
+{
+    void *target_obj;
+    AVDictionary *src;
+    const AVOption *o = av_opt_find2(obj, name, NULL, 0, search_flags, &target_obj);
+
+    if (!o || !target_obj)
+        return AVERROR_OPTION_NOT_FOUND;
+    if (o->type != AV_OPT_TYPE_DICT)
+        return AVERROR(EINVAL);
+
+    src = *(AVDictionary **)(((uint8_t *)target_obj) + o->offset);
+    av_dict_copy(out_val, src, 0);
+
+    return 0;
+}
+
 int av_opt_flag_is_set(void *obj, const char *field_name, const char *flag_name)
 {
     const AVOption *field = av_opt_find(obj, field_name, NULL, 0, 0);
@@ -539,7 +574,8 @@ void av_opt_set_defaults(void *s)
                 av_opt_set(s, opt->name, opt->default_val.str, 0);
                 break;
             case AV_OPT_TYPE_BINARY:
-                /* Cannot set default for binary */
+            case AV_OPT_TYPE_DICT:
+                /* Cannot set defaults for these types */
             break;
             default:
                 av_log(s, AV_LOG_DEBUG, "AVOption type %d of option %s not implemented yet\n", opt->type, opt->name);
@@ -621,9 +657,21 @@ int av_set_options_string(void *ctx, const char *opts,
 void av_opt_free(void *obj)
 {
     const AVOption *o = NULL;
-    while ((o = av_opt_next(obj, o)))
-        if (o->type == AV_OPT_TYPE_STRING || o->type == AV_OPT_TYPE_BINARY)
+    while ((o = av_opt_next(obj, o))) {
+        switch (o->type) {
+        case AV_OPT_TYPE_STRING:
+        case AV_OPT_TYPE_BINARY:
             av_freep((uint8_t *)obj + o->offset);
+            break;
+
+        case AV_OPT_TYPE_DICT:
+            av_dict_free((AVDictionary **)(((uint8_t *)obj) + o->offset));
+            break;
+
+        default:
+            break;
+        }
+    }
 }
 
 int av_opt_set_dict(void *obj, AVDictionary **options)

libavutil/opt.h

@@ -224,6 +224,7 @@ enum AVOptionType{
     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_DICT,
     AV_OPT_TYPE_CONST = 128,
 };
 
@@ -325,7 +326,7 @@ 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.
+ * Free all allocated objects in obj.
  */
 void av_opt_free(void *obj);
 
@@ -491,11 +492,16 @@ const AVClass *av_opt_child_class_next(const AVClass *parent, const AVClass *pre
  * 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);
+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);
+/**
+ * @note Any old dictionary present is discarded and replaced with a copy of the new one. The
+ * caller still owns val is and responsible for freeing it.
+ */
+int av_opt_set_dict_val(void *obj, const char *name, const AVDictionary *val, int search_flags);
 /**
  * @}
  */
@@ -515,10 +521,15 @@ int av_opt_set_bin   (void *obj, const char *name, const uint8_t *val, int size,
 /**
  * @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);
+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);
+/**
+ * @param[out] out_val The returned dictionary is a copy of the actual value and must
+ * be freed with av_dict_free() by the caller
+ */
+int av_opt_get_dict_val(void *obj, const char *name, int search_flags, AVDictionary **out_val);
 /**
  * @}
  * @}

libavutil/version.h

@@ -54,7 +54,7 @@
  */
 
 #define LIBAVUTIL_VERSION_MAJOR 54
-#define LIBAVUTIL_VERSION_MINOR  1
+#define LIBAVUTIL_VERSION_MINOR  2
 #define LIBAVUTIL_VERSION_MICRO  0
 
 #define LIBAVUTIL_VERSION_INT   AV_VERSION_INT(LIBAVUTIL_VERSION_MAJOR, \