lavf/matroskaenc: Check for valid metadata before creating tags

Tags must have at least one SimpleTag element to be spec conformant.
Updated lavf-mkv and seek-lavf-mkv FATE references as the tests were affected by
this.

Fixes ticket #2785

Signed-off-by: James Almer <jamrial@gmail.com>
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

1 files changed, 15 insertions, 3 deletions

diff --git a/libavformat/matroskaenc.c b/libavformat/matroskaenc.c
index 968467c730..2c414e8c2f 100644
--- a/libavformat/matroskaenc.c
+++ b/libavformat/matroskaenc.c
@@ -869,6 +869,18 @@ static int mkv_write_tag(AVFormatContext *s, AVDictionary *m, unsigned int eleme
     return 0;
 }
 
+static int mkv_check_tag(AVDictionary *m)
+{
+    AVDictionaryEntry *t = NULL;
+    int ret = 0;
+
+    while ((t = av_dict_get(m, "", t, AV_DICT_IGNORE_SUFFIX)))
+        if (av_strcasecmp(t->key, "title") && av_strcasecmp(t->key, "stereo_mode"))
+            ret++;
+
+    return ret;
+}
+
 static int mkv_write_tags(AVFormatContext *s)
 {
     ebml_master tags = {0};
@@ -876,7 +888,7 @@ static int mkv_write_tags(AVFormatContext *s)
 
     ff_metadata_conv_ctx(s, ff_mkv_metadata_conv, NULL);
 
-    if (av_dict_get(s->metadata, "", NULL, AV_DICT_IGNORE_SUFFIX)) {
+    if (mkv_check_tag(s->metadata)) {
         ret = mkv_write_tag(s, s->metadata, 0, 0, &tags);
         if (ret < 0) return ret;
     }
@@ -884,7 +896,7 @@ static int mkv_write_tags(AVFormatContext *s)
     for (i = 0; i < s->nb_streams; i++) {
         AVStream *st = s->streams[i];
 
-        if (!av_dict_get(st->metadata, "", 0, AV_DICT_IGNORE_SUFFIX))
+        if (!mkv_check_tag(st->metadata))
             continue;
 
         ret = mkv_write_tag(s, st->metadata, MATROSKA_ID_TAGTARGETS_TRACKUID, i + 1, &tags);
@@ -894,7 +906,7 @@ static int mkv_write_tags(AVFormatContext *s)
     for (i = 0; i < s->nb_chapters; i++) {
         AVChapter *ch = s->chapters[i];
 
-        if (!av_dict_get(ch->metadata, "", NULL, AV_DICT_IGNORE_SUFFIX))
+        if (!mkv_check_tag(ch->metadata))
             continue;
 
         ret = mkv_write_tag(s, ch->metadata, MATROSKA_ID_TAGTARGETS_CHAPTERUID, ch->id, &tags);