By comparing versions of dictionaries, it's possible to detect if metadata
has changed.
---
libavutil/dict.c | 8 ++++++++
libavutil/dict.h | 10 ++++++++++
2 files changed, 18 insertions(+)
diff --git a/libavutil/dict.c b/libavutil/dict.c
index 7b4dbf2..113afe4 100644
--- a/libavutil/dict.c
+++ b/libavutil/dict.c
@@ -27,6 +27,7 @@
struct AVDictionary {
int count;
+ uint64_t version;
AVDictionaryEntry *elems;
};
@@ -75,6 +76,8 @@ int av_dict_set(AVDictionary **pm, const char *key, const
char *value,
if (!m)
m = *pm = av_mallocz(sizeof(*m));
+ m->version++;
+
if (tag) {
if (flags & AV_DICT_DONT_OVERWRITE)
return 0;
@@ -117,6 +120,11 @@ int av_dict_set(AVDictionary **pm, const char *key, const
char *value,
return 0;
}
+uint64_t av_dict_version(const AVDictionary *m)
+{
+ return m ? m->version : 0;
+}
+
static int parse_key_value_pair(AVDictionary **pm, const char **buf,
const char *key_val_sep, const char *pairs_sep,
int flags)
diff --git a/libavutil/dict.h b/libavutil/dict.h
index e4aee27..1679119 100644
--- a/libavutil/dict.h
+++ b/libavutil/dict.h
@@ -25,6 +25,8 @@
#ifndef AVUTIL_DICT_H
#define AVUTIL_DICT_H
+#include <stdint.h>
+
/**
* @addtogroup lavu_dict AVDictionary
* @ingroup lavu_data
@@ -107,6 +109,14 @@ int av_dict_count(const AVDictionary *m);
int av_dict_set(AVDictionary **pm, const char *key, const char *value, int
flags);
/**
+ * Get the version of number for the current state of the dictionary. Whenever
+ * an item is changed, this number is incremented.
+ *
+ * @return >= 0 for any changes, 0 for an empty dictionary
+ */
+uint64_t av_dict_version(const AVDictionary *m);
+
+/**
* Parse the key/value pairs list and add to a dictionary.
*
* @param key_val_sep a 0-terminated list of characters used to separate
--
2.0.0.rc2
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