ogg: update event_flags with STREAM_/METADATA_UPDATED whenever metadata changes.

Originally, AVFormatContext and a metadata dict were provided to ff_vorbis_comment(),
but this presented issues if an AVStream was being updated or the metadata on
AVFormatContext wasn't actually being updated. To remedy this, ff_vorbis_stream_comment()
explicitly updates a stream's metadata and sets any necessary flags.

ff_vorbis_comment() does not modify any flags, and any calls to it that update
AVFormatContext's metadata (just a single call) must also update
AVFormatContext.event_flags after detecting any metadata changes to the provided
dictionary, as signaled by a positive return value.
Signed-off-by: Anton Khirnov <anton@khirnov.net>

libavformat/flacdec.c

@@ -141,8 +141,11 @@ static int flac_read_header(AVFormatContext *s)
             if (metadata_type == FLAC_METADATA_TYPE_VORBIS_COMMENT) {
                 AVDictionaryEntry *chmask;
 
-                if (ff_vorbis_comment(s, &s->metadata, buffer, metadata_size, 1)) {
+                ret = ff_vorbis_comment(s, &s->metadata, buffer, metadata_size, 1);
+                if (ret < 0) {
                     av_log(s, AV_LOG_WARNING, "error parsing VorbisComment metadata\n");
+                } else if (ret > 0) {
+                    s->event_flags |= AVFMT_EVENT_FLAG_METADATA_UPDATED;
                 }
 
                 /* parse the channels mask if present */

libavformat/oggdec.h

@@ -125,6 +125,9 @@ extern const struct ogg_codec ff_vorbis_codec;
 int ff_vorbis_comment(AVFormatContext *ms, AVDictionary **m,
                       const uint8_t *buf, int size, int parse_picture);
 
+int ff_vorbis_stream_comment(AVFormatContext *as, AVStream *st,
+                             const uint8_t *buf, int size);
+
 static inline int
 ogg_find_stream (struct ogg * ogg, int serial)
 {

libavformat/oggparsecelt.c

@@ -79,7 +79,7 @@ static int celt_header(AVFormatContext *s, int idx)
     } else if (priv && priv->extra_headers_left) {
         /* Extra headers (vorbiscomment) */
 
-        ff_vorbis_comment(s, &st->metadata, p, os->psize, 1);
+        ff_vorbis_stream_comment(s, st, p, os->psize);
         priv->extra_headers_left--;
         return 1;
     } else {

libavformat/oggparseflac.c

@@ -69,7 +69,7 @@ flac_header (AVFormatContext * s, int idx)
 
         avpriv_set_pts_info(st, 64, 1, st->codec->sample_rate);
     } else if (mdt == FLAC_METADATA_TYPE_VORBIS_COMMENT) {
-        ff_vorbis_comment (s, &st->metadata, os->buf + os->pstart + 4, os->psize - 4, 1);
+        ff_vorbis_stream_comment(s, st, os->buf + os->pstart + 4, os->psize - 4);
     }
 
     return 1;

libavformat/oggparseogm.c

@@ -97,7 +97,7 @@ ogm_header(AVFormatContext *s, int idx)
     } else if (bytestream2_peek_byte(&p) == 3) {
         bytestream2_skip(&p, 7);
         if (bytestream2_get_bytes_left(&p) > 1)
-            ff_vorbis_comment(s, &st->metadata, p.buffer, bytestream2_get_bytes_left(&p) - 1, 1);
+            ff_vorbis_stream_comment(s, st, p.buffer, bytestream2_get_bytes_left(&p) - 1);
     }
 
     return 1;

libavformat/oggparseopus.c

@@ -74,7 +74,7 @@ static int opus_header(AVFormatContext *avf, int idx)
     if (priv->need_comments) {
         if (os->psize < 8 || memcmp(packet, "OpusTags", 8))
             return AVERROR_INVALIDDATA;
-        ff_vorbis_comment(avf, &st->metadata, packet + 8, os->psize - 8, 1);
+        ff_vorbis_stream_comment(avf, st, packet + 8, os->psize - 8);
         priv->need_comments--;
         return 1;
     }

libavformat/oggparsespeex.c

@@ -79,7 +79,7 @@ static int speex_header(AVFormatContext *s, int idx) {
 
         avpriv_set_pts_info(st, 64, 1, st->codec->sample_rate);
     } else
-        ff_vorbis_comment(s, &st->metadata, p, os->psize, 1);
+        ff_vorbis_stream_comment(s, st, p, os->psize);
 
     spxp->seq++;
     return 1;

libavformat/oggparsetheora.c

@@ -116,7 +116,7 @@ static int theora_header(AVFormatContext *s, int idx)
     }
     break;
     case 0x81:
-        ff_vorbis_comment(s, &st->metadata, os->buf + os->pstart + 7, os->psize - 7, 1);
+        ff_vorbis_stream_comment(s, st, os->buf + os->pstart + 7, os->psize - 7);
     case 0x82:
         if (!thp->version)
             return AVERROR_INVALIDDATA;

libavformat/oggparsevorbis.c

@@ -71,12 +71,25 @@ static int ogm_chapter(AVFormatContext *as, uint8_t *key, uint8_t *val)
     return 1;
 }
 
+int ff_vorbis_stream_comment(AVFormatContext *as, AVStream *st,
+                             const uint8_t *buf, int size)
+{
+    int updates = ff_vorbis_comment(as, &st->metadata, buf, size, 1);
+
+    if (updates > 0) {
+        st->event_flags |= AVSTREAM_EVENT_FLAG_METADATA_UPDATED;
+    }
+
+    return updates;
+}
+
 int ff_vorbis_comment(AVFormatContext *as, AVDictionary **m,
                       const uint8_t *buf, int size,
                       int parse_picture)
 {
     const uint8_t *p   = buf;
     const uint8_t *end = buf + size;
+    int updates        = 0;
     unsigned n, j;
     int s;
 
@@ -156,12 +169,14 @@ int ff_vorbis_comment(AVFormatContext *as, AVDictionary **m,
                     av_log(as, AV_LOG_WARNING, "Failed to parse cover art block.\n");
                     continue;
                 }
-            } else if (!ogm_chapter(as, tt, ct))
+            } else if (!ogm_chapter(as, tt, ct)) {
+                updates++;
                 av_dict_set(m, tt, ct,
                             AV_DICT_DONT_STRDUP_KEY |
                             AV_DICT_DONT_STRDUP_VAL);
             }
         }
+    }
 
     if (p != end)
         av_log(as, AV_LOG_INFO,
@@ -172,7 +187,7 @@ int ff_vorbis_comment(AVFormatContext *as, AVDictionary **m,
 
     ff_metadata_conv(m, NULL, ff_vorbiscomment_metadata_conv);
 
-    return 0;
+    return updates;
 }
 
 /*
@@ -305,8 +320,8 @@ static int vorbis_header(AVFormatContext *s, int idx)
         }
     } else if (os->buf[os->pstart] == 3) {
         if (os->psize > 8 &&
-            ff_vorbis_comment(s, &st->metadata, os->buf + os->pstart + 7,
-                              os->psize - 8, 1) >= 0) {
+            ff_vorbis_stream_comment(s, st, os->buf + os->pstart + 7,
+                                     os->psize - 8) >= 0) {
             unsigned new_len;
 
             int ret = ff_replaygain_export(st, st->metadata);