@@ -19,6 +19,7 @@

  */

 #include <strings.h>

+#include "avstring.h"

 #include "dict.h"

 #include "internal.h"

 #include "mem.h"

@@ -51,6 +52,7 @@ int av_dict_set(AVDictionary **pm, const char *key, const char *value, int flags

 {

     AVDictionary      *m = *pm;

     AVDictionaryEntry *tag = av_dict_get(m, key, NULL, flags);

+    char *oldval = NULL;

     if(!m)

         m = *pm = av_mallocz(sizeof(*m));

@@ -58,7 +60,10 @@ int av_dict_set(AVDictionary **pm, const char *key, const char *value, int flags

     if(tag) {

         if (flags & AV_DICT_DONT_OVERWRITE)

             return 0;

-        av_free(tag->value);

+        if (flags & AV_DICT_APPEND)

+            oldval = tag->value;

+        else

+            av_free(tag->value);

         av_free(tag->key);

         *tag = m->elems[--m->count];

     } else {

@@ -75,6 +80,12 @@ int av_dict_set(AVDictionary **pm, const char *key, const char *value, int flags

         m->elems[m->count].key  = av_strdup(key  );

         if (flags & AV_DICT_DONT_STRDUP_VAL) {

             m->elems[m->count].value = value;

+        } else if (oldval && flags & AV_DICT_APPEND) {

+            int len = strlen(oldval) + strlen(value) + 1;

+            if (!(oldval = av_realloc(oldval, len)))

+                return AVERROR(ENOMEM);

+            av_strlcat(oldval, value, len);

+            m->elems[m->count].value = oldval;

         } else

             m->elems[m->count].value = av_strdup(value);

         m->count++;

@@ -29,6 +29,8 @@

 #define AV_DICT_DONT_STRDUP_KEY 4

 #define AV_DICT_DONT_STRDUP_VAL 8

 #define AV_DICT_DONT_OVERWRITE 16   ///< Don't overwrite existing entries.

+#define AV_DICT_APPEND         32   /**< If the entry already exists, append to it.  Note that no

+                                      delimiter is added, the strings are simply concatenated. */

 typedef struct {

     char *key;