3 files changed, 70 insertions, 2 deletions

diff --git a/libavformat/avformat.h b/libavformat/avformat.h
index cc20fbb884..94764f3875 100644
--- a/libavformat/avformat.h
+++ b/libavformat/avformat.h
@@ -46,6 +46,8 @@ unsigned avformat_version(void);
 
 #include "avio.h"
 
+struct AVFormatContext;
+
 
 /*
  * Public Metadata API.
@@ -77,6 +79,7 @@ typedef struct {
 }AVMetadataTag;
 
 typedef struct AVMetadata AVMetadata;
+typedef struct AVMetadataConv AVMetadataConv;
 
 /**
  * Gets a metadata element with matching key.
@@ -96,6 +99,15 @@ av_metadata_get(AVMetadata *m, const char *key, const AVMetadataTag *prev, int f
 int av_metadata_set(AVMetadata **pm, const char *key, const char *value);
 
 /**
+ * Convert all the metadata sets from ctx according to the source and
+ * destination conversion tables.
+ * @param d_conv destination tags format conversion table
+ * @param s_conv source tags format conversion table
+ */
+void av_metadata_conv(struct AVFormatContext *ctx,const AVMetadataConv *d_conv,
+                                                  const AVMetadataConv *s_conv);
+
+/**
  * Frees all the memory allocated for an AVMetadata struct.
  */
 void av_metadata_free(AVMetadata **m);
@@ -220,8 +232,6 @@ typedef struct AVFrac {
 
 struct AVCodecTag;
 
-struct AVFormatContext;
-
 /** This structure contains the data a format has to probe a file. */
 typedef struct AVProbeData {
     const char *filename;
@@ -299,6 +309,8 @@ typedef struct AVOutputFormat {
 
     enum CodecID subtitle_codec; /**< default subtitle codec */
 
+    AVMetadataConv *metadata_conv;
+
     /* private fields */
     struct AVOutputFormat *next;
 } AVOutputFormat;
@@ -378,6 +390,8 @@ typedef struct AVInputFormat {
      */
     int (*read_seek2)(struct AVFormatContext *s, int stream_index, int64_t min_ts, int64_t ts, int64_t max_ts, int flags);
 
+    AVMetadataConv *metadata_conv;
+
     /* private fields */
     struct AVInputFormat *next;
 } AVInputFormat;
diff --git a/libavformat/metadata.c b/libavformat/metadata.c
index 1a2a907d98..0ed3cf709a 100644
--- a/libavformat/metadata.c
+++ b/libavformat/metadata.c
@@ -18,6 +18,8 @@
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  */
 
+#include <strings.h>
+#include "avformat.h"
 #include "metadata.h"
 
 AVMetadataTag *
@@ -89,3 +91,50 @@ void av_metadata_free(AVMetadata **pm)
     }
     av_freep(pm);
 }
+
+static void metadata_conv(AVMetadata **pm, const AVMetadataConv *d_conv,
+                                           const AVMetadataConv *s_conv)
+{
+    /* TODO: use binary search to look up the two conversion tables
+       if the tables are getting big enough that it would matter speed wise */
+    const AVMetadataConv *s_conv1 = s_conv, *d_conv1 = d_conv, *sc, *dc;
+    AVMetadataTag *mtag = NULL;
+    AVMetadata *dst = NULL;
+    const char *key, *key2;
+
+    while((mtag=av_metadata_get(*pm, "", mtag, AV_METADATA_IGNORE_SUFFIX))) {
+        key = key2 = mtag->key;
+        if (s_conv != d_conv) {
+            if (!s_conv)
+                s_conv1 = (const AVMetadataConv[2]){{key,key}};
+            for (sc=s_conv1; sc->native; sc++)
+                if (!strcasecmp(key, sc->native)) {
+                    key2 = sc->generic;
+                    break;
+                }
+            if (!d_conv)
+                d_conv1 = (const AVMetadataConv[2]){{key2,key2}};
+            for (dc=d_conv1; dc->native; dc++)
+                if (!strcasecmp(key2, dc->generic)) {
+                    key = dc->native;
+                    break;
+                }
+        }
+        av_metadata_set(&dst, key, mtag->value);
+    }
+    av_metadata_free(pm);
+    *pm = dst;
+}
+
+void av_metadata_conv(AVFormatContext *ctx, const AVMetadataConv *d_conv,
+                                            const AVMetadataConv *s_conv)
+{
+    int i;
+    metadata_conv(&ctx->metadata, d_conv, s_conv);
+    for (i=0; i<ctx->nb_streams ; i++)
+        metadata_conv(&ctx->streams [i]->metadata, d_conv, s_conv);
+    for (i=0; i<ctx->nb_chapters; i++)
+        metadata_conv(&ctx->chapters[i]->metadata, d_conv, s_conv);
+    for (i=0; i<ctx->nb_programs; i++)
+        metadata_conv(&ctx->programs[i]->metadata, d_conv, s_conv);
+}
diff --git a/libavformat/metadata.h b/libavformat/metadata.h
index a906df47c3..9ec2265a41 100644
--- a/libavformat/metadata.h
+++ b/libavformat/metadata.h
@@ -35,6 +35,11 @@ struct AVMetadata{
     AVMetadataTag *elems;
 };
 
+struct AVMetadataConv{
+    const char *native;
+    const char *generic;
+};
+
 #if LIBAVFORMAT_VERSION_MAJOR < 53
 void ff_metadata_demux_compat(AVFormatContext *s);
 void ff_metadata_mux_compat(AVFormatContext *s);