Generic metadata API.

avi is updated as example.
No version bump, the API still might change slightly ...
No update to ffmpeg.c as requested by aurel.

Originally committed as revision 16424 to svn://svn.ffmpeg.org/ffmpeg/trunk

1 files changed, 45 insertions, 0 deletions

diff --git a/libavcodec/avcodec.h b/libavcodec/avcodec.h
index e45f7d6dfb..7038d2d2c4 100644
--- a/libavcodec/avcodec.h
+++ b/libavcodec/avcodec.h
@@ -400,6 +400,51 @@ enum SampleFormat {
  */
 #define FF_MIN_BUFFER_SIZE 16384
 
+
+/*
+ * public Metadata API.
+ * Important concepts, to keep in mind
+ * 1. keys are unique, there are never 2 tags with equal keys, this is also
+ *    meant semantically that is a demuxer should not knowingly produce
+ *    several keys that are litterally different but semantically identical,
+ *    like key=Author5, key=Author6.
+ *    All authors have to be placed in the same tag for the case of Authors.
+ * 2. Metadata is flat, there are no subtags, if you for whatever obscene
+ *    reason want to store the email address of the child of producer alice
+ *    and actor bob, that could have key=alice_and_bobs_childs_email_address.
+ * 3. A tag whichs value is translated has the ISO 639 3-letter language code
+ *    with a '-' between appended. So for example Author-ger=Michael, Author-eng=Mike
+ *    the original/default language is in the unqualified "Author"
+ *    A demuxer should set a default if it sets any translated tag.
+ */
+
+#define AV_METADATA_IGNORE_CASE     1
+#define AV_METADATA_IGNORE_SUFFIX   2
+
+typedef struct {
+    char *key;
+    char *value;
+}AVMetaDataTag;
+
+struct AVMetaData;
+
+/**
+ * gets a metadata element with matching key.
+ * @param prev set to the previous matching element to find the next.
+ * @param flags allows case as well as suffix insensitive comparissions.
+ * @return found tag or NULL, changing key or value leads to undefined behavior.
+ */
+AVMetaDataTag *
+av_metadata_get(struct AVMetaData *m, const char *key, const AVMetaDataTag *prev, int flags);
+
+/**
+ * sets the given tag in m, overwriting an existing tag.
+ * @param tag tag to add to m, key and value will be av_strduped.
+ * @return >= 0 if success otherwise error code that is <0.
+ */
+int av_metadata_set(struct AVMetaData **m, AVMetaDataTag tag);
+
+
 /**
  * motion estimation type.
  */