Move metadata API from avcodec to avformat.

Originally committed as revision 16425 to svn://svn.ffmpeg.org/ffmpeg/trunk

4 files changed, 159 insertions, 1 deletions

diff --git a/libavformat/Makefile b/libavformat/Makefile
index f6ef3a71b4..303242d962 100644
--- a/libavformat/Makefile
+++ b/libavformat/Makefile
@@ -5,7 +5,7 @@ FFLIBS = avcodec avutil
 
 HEADERS = avformat.h avio.h rtsp.h rtspcodes.h
 
-OBJS = allformats.o cutils.o os_support.o sdp.o utils.o
+OBJS = allformats.o cutils.o metadata.o os_support.o sdp.o utils.o
 
 # muxers/demuxers
 OBJS-$(CONFIG_AAC_DEMUXER)               += raw.o
diff --git a/libavformat/avformat.h b/libavformat/avformat.h
index 46e692452e..39dc4765a8 100644
--- a/libavformat/avformat.h
+++ b/libavformat/avformat.h
@@ -46,6 +46,51 @@ unsigned avformat_version(void);
 
 #include "avio.h"
 
+
+/*
+ * 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);
+
+
 /* packet functions */
 
 typedef struct AVPacket {
diff --git a/libavformat/metadata.c b/libavformat/metadata.c
new file mode 100644
index 0000000000..d223d7c0d9
--- /dev/null
+++ b/libavformat/metadata.c
@@ -0,0 +1,75 @@
+/*
+ * copyright (c) 2009 Michael Niedermayer
+ *
+ * This file is part of FFmpeg.
+ *
+ * FFmpeg is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * FFmpeg is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with FFmpeg; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+#include "metadata.h"
+
+AVMetaDataTag *
+av_metadata_get(struct AVMetaData *m, const char *key, const AVMetaDataTag *prev, int flags)
+{
+    unsigned int i, j;
+
+    if(!m)
+        return NULL;
+
+    if(prev) i= prev - m->elems + 1;
+    else     i= 0;
+
+    for(; i<m->count; i++){
+        const char *s= m->elems[i].key;
+        if(flags & AV_METADATA_IGNORE_CASE) for(j=0; toupper(s[j]) == toupper(key[j]) && key[j]; j++);
+        else                                for(j=0;         s[j]  ==         key[j]  && key[j]; j++);
+        if(key[j])
+            continue;
+        if(s[j] && !(flags & AV_METADATA_IGNORE_SUFFIX))
+            continue;
+        return &m->elems[i];
+    }
+    return NULL;
+}
+
+int av_metadata_set(struct AVMetaData **pm, AVMetaDataTag elem)
+{
+    struct AVMetaData *m= *pm;
+    AVMetaDataTag *tag= av_metadata_get(m, elem.key, NULL, 0);
+
+    if(!m)
+        m=*pm= av_mallocz(sizeof(*m));
+
+    if(tag){
+        av_free(tag->value);
+        av_free(tag->key);
+        *tag= m->elems[--m->count];
+    }else{
+        AVMetaDataTag *tmp= av_realloc(m->elems, (m->count+1) * sizeof(*m->elems));
+        if(tmp){
+            m->elems= tmp;
+        }else
+            return AVERROR(ENOMEM);
+    }
+    if(elem.value){
+        elem.key  = av_strdup(elem.key  );
+        elem.value= av_strdup(elem.value);
+        m->elems[m->count++]= elem;
+    }
+    if(!m->count)
+        av_freep(pm);
+
+    return 0;
+}
diff --git a/libavformat/metadata.h b/libavformat/metadata.h
new file mode 100644
index 0000000000..e9ada571a1
--- /dev/null
+++ b/libavformat/metadata.h
@@ -0,0 +1,38 @@
+/*
+ * copyright (c) 2009 Michael Niedermayer
+ *
+ * This file is part of FFmpeg.
+ *
+ * FFmpeg is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * FFmpeg is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with FFmpeg; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+#ifndef AVFORMAT_METADATA_H
+#define AVFORMAT_METADATA_H
+
+/**
+ * @file metadata.h
+ * internal metadata API header
+ * see avformat.h or the public API!
+ */
+
+
+#include "avformat.h"
+
+struct AVMetaData{
+    int count;
+    AVMetaDataTag *elems;
+};
+
+#endif /* AVFORMAT_METADATA_H */