*** Bug 112569 has been marked as a duplicate of this bug. ***

Hm, seems like there's a lot of interest for FLAC...

http://flac.sourceforge.net/format.html

"VORBIS_COMMENT: This block is for storing a list of human-readable
name/value pairs. Values are encoded using UTF-8. It is an
implementation of the Vorbis comment specification. This is the only
officially supported tagging mechanism in FLAC. There may be only one
VORBIS_COMMENT block in a stream."

According to Ross (rburton), FLAC__file_encoder_set_metadata() is the
way to go here.

So, according to the docs, it'd look like:

static void
set_metadata (FLAC__StreamEncoder *encoder,
              GstCaps             *caps)
{
  FLAC__StreamMetadata *meta = g_malloc(sizeof(FLAC__StreamMetadata));
  const gchar **meta_types = { "TITLE", "VERSION", "ALBUM", "TRACKNUMBER",
                               "ARTIST", "PERFORMER", "COPYRIGHT",
"LICENSE",
                               "ORGANISATION", "DESCRIPTION", "GENRE",
"DATE",
                               "LOCATION", "CONTACT", "ISRC", NULL };

  meta->type = FLAC__METADATA_TYPE_VORBIS_COMMENT;
  meta->data.vorbis_comment.vendor_string.length =
strlen(FLAC__VENDOR_STRING);
  meta->data.vorbis_comment.vendor_string.entry = FLAC__VENDOR_STRING;
  meta->data.num_comments = 0;
  meta->data.comments =
g_malloc(sizeof(FLAC__StreamMetadata_VorbisComment_Entry) * 15); /* max */

  /* num_comments */
  for ( ; *meta_types != NULL; meta_types++) {
    if (gst_caps_has_property(caps, *meta_types)) {
      gchar *entry;
      gst_caps_get_string(caps, *meta_types, &entry);
      meta->data.comments[meta->data.num_comments].length =
strlen(entry) + strlen(*meta_types) + 1;
      meta->data.comments[meta.data.num_comments].entry =
g_strdup_printf("%s=%s", *meta_types, entry);

      meta->data.num_comments++;
    }
  }

  FLAC__file_encoder_set_metadata(encoder, &meta, 1);
}

After initting the encoder, we should free the struct somewhere.
Besides, it's untested. However, it's a start. :).

From what I understand, flacdec would have to use
FLAC__stream_decoder_set_metadata_callback() to get a metadata
callback when the file in question contains metadata.

The callback would then have to check whether the metadata block is a
VorbisComment metadata block and - if yes - read the metadata and
signal that it has metadata using the proper GStreamer callbacks
(g_object_notify(object, "metadata") or so)... The way in which we
interpret is is the same as above.

apoc just notified me that he added this last week, so I shouldn't
have written all that... Current stuff remaining is that we use the
vorbis comment tags (in caps, see above) for metadata, and we should
translate that to gstreamer tags (lowercase).

Hm, we have multiple bugs describing the same issue...

*** This bug has been marked as a duplicate of 110544 ***