riff: do not write empty INFO tags

Signed-off-by: Anton Khirnov <anton@khirnov.net>

1 files changed, 19 insertions, 1 deletions

diff --git a/libavformat/riff.c b/libavformat/riff.c
index 3d805d8884..d591aa81e0 100644
--- a/libavformat/riff.c
+++ b/libavformat/riff.c
@@ -709,6 +709,19 @@ int ff_read_riff_info(AVFormatContext *s, int64_t size)
     return 0;
 }
 
+static int riff_has_valid_tags(AVFormatContext *s)
+{
+    int i;
+    AVDictionaryEntry *t = NULL;
+
+    for (i = 0; *ff_riff_tags[i]; i++) {
+        if ((t = av_dict_get(s->metadata, ff_riff_tags[i], NULL, AV_DICT_MATCH_CASE)))
+            return 1;
+    }
+
+    return 0;
+}
+
 void ff_riff_write_info_tag(AVIOContext *pb, const char *tag, const char *str)
 {
     int len = strlen(str);
@@ -729,9 +742,14 @@ void ff_riff_write_info(AVFormatContext *s)
     int64_t list_pos;
     AVDictionaryEntry *t = NULL;
 
+    ff_metadata_conv(&s->metadata, ff_riff_info_conv, NULL);
+
+    /* writing empty LIST is not nice and may cause problems */
+    if (!riff_has_valid_tags(s))
+        return;
+
     list_pos = ff_start_tag(pb, "LIST");
     ffio_wfourcc(pb, "INFO");
-    ff_metadata_conv(&s->metadata, ff_riff_info_conv, NULL);
     for (i = 0; *ff_riff_tags[i]; i++) {
         if ((t = av_dict_get(s->metadata, ff_riff_tags[i], NULL, AV_DICT_MATCH_CASE)))
             ff_riff_write_info_tag(s->pb, t->key, t->value);