Add flags to prevent strdup() on arguments to av_metadata_set2().

I cannot use the same ABI as ffmbc as value 2 is already used in ffmpeg,
besides the name AV_METADATA_NONCONST* makes no sense to me.
Add av_metadata_set2() that takes flags.

Originally committed as revision 20834 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavformat/avformat.h

@@ -22,7 +22,7 @@
 #define AVFORMAT_AVFORMAT_H
 
 #define LIBAVFORMAT_VERSION_MAJOR 52
-#define LIBAVFORMAT_VERSION_MINOR 42
+#define LIBAVFORMAT_VERSION_MINOR 43
 #define LIBAVFORMAT_VERSION_MICRO  0
 
 #define LIBAVFORMAT_VERSION_INT AV_VERSION_INT(LIBAVFORMAT_VERSION_MAJOR, \
@@ -81,6 +81,8 @@ struct AVFormatContext;
 
 #define AV_METADATA_MATCH_CASE      1
 #define AV_METADATA_IGNORE_SUFFIX   2
+#define AV_METADATA_DONT_STRDUP_KEY 4
+#define AV_METADATA_DONT_STRDUP_VAL 8
 
 typedef struct {
     char *key;
@@ -99,6 +101,7 @@ typedef struct AVMetadataConv AVMetadataConv;
 AVMetadataTag *
 av_metadata_get(AVMetadata *m, const char *key, const AVMetadataTag *prev, int flags);
 
+#if LIBAVFORMAT_VERSION_MAJOR == 52
 /**
  * Sets the given tag in m, overwriting an existing tag.
  * @param key tag key to add to m (will be av_strduped)
@@ -106,6 +109,15 @@ av_metadata_get(AVMetadata *m, const char *key, const AVMetadataTag *prev, int f
  * @return >= 0 on success otherwise an error code <0
  */
 int av_metadata_set(AVMetadata **pm, const char *key, const char *value);
+#endif
+
+/**
+ * Sets the given tag in m, overwriting an existing tag.
+ * @param key tag key to add to m (will be av_strduped depending on flags)
+ * @param value tag value to add to m (will be av_strduped depending on flags)
+ * @return >= 0 on success otherwise an error code <0
+ */
+int av_metadata_set2(AVMetadata **pm, const char *key, const char *value, int flags);
 
 /**
  * Converts all the metadata sets from ctx according to the source and

libavformat/metadata.c

@@ -46,7 +46,7 @@ av_metadata_get(AVMetadata *m, const char *key, const AVMetadataTag *prev, int f
     return NULL;
 }
 
-int av_metadata_set(AVMetadata **pm, const char *key, const char *value)
+int av_metadata_set2(AVMetadata **pm, const char *key, const char *value, int flags)
 {
     AVMetadata *m= *pm;
     AVMetadataTag *tag= av_metadata_get(m, key, NULL, AV_METADATA_MATCH_CASE);
@@ -66,7 +66,13 @@ int av_metadata_set(AVMetadata **pm, const char *key, const char *value)
             return AVERROR(ENOMEM);
     }
     if(value){
+        if(flags & AV_METADATA_DONT_STRDUP_KEY){
+            m->elems[m->count].key  = key;
+        }else
         m->elems[m->count].key  = av_strdup(key  );
+        if(flags & AV_METADATA_DONT_STRDUP_VAL){
+            m->elems[m->count].value= value;
+        }else
         m->elems[m->count].value= av_strdup(value);
         m->count++;
     }
@@ -78,6 +84,13 @@ int av_metadata_set(AVMetadata **pm, const char *key, const char *value)
     return 0;
 }
 
+#if LIBAVFORMAT_VERSION_MAJOR == 52
+int av_metadata_set(AVMetadata **pm, const char *key, const char *value)
+{
+    return av_metadata_set2(pm, key, value, 0);
+}
+#endif
+
 void av_metadata_free(AVMetadata **pm)
 {
     AVMetadata *m= *pm;