demux_mkv: concatenate multiple tags

Instead of just picking the last tag that was encountered. The order of
the tags still depends on the file order.

This is probably wrong, and we should respect TargetTypeValue. But
despite staring at the spec, I have no idea what the hell this should
do, so fuck that.

Fixes: #7604

1 files changed, 8 insertions, 2 deletions

diff --git a/demux/demux_mkv.c b/demux/demux_mkv.c
index bb1125a0f2..6eb48cbeea 100644
--- a/demux/demux_mkv.c
+++ b/demux/demux_mkv.c
@@ -1103,8 +1103,14 @@ static void process_tags(demuxer_t *demuxer)
         if (dst) {
             for (int j = 0; j < tag.n_simple_tag; j++) {
                 if (tag.simple_tag[j].tag_name && tag.simple_tag[j].tag_string) {
-                    mp_tags_set_str(dst, tag.simple_tag[j].tag_name,
-                                         tag.simple_tag[j].tag_string);
+                    char *name = tag.simple_tag[j].tag_name;
+                    char *val = tag.simple_tag[j].tag_string;
+                    char *old = mp_tags_get_str(dst, name);
+                    if (old)
+                        val = talloc_asprintf(NULL, "%s / %s", old, val);
+                    mp_tags_set_str(dst, name, val);
+                    if (old)
+                        talloc_free(val);
                 }
             }
         }