flac: get CUE track titles from additional FLAC comments

The cue sheet embedded in a flac file doen't contain any information
about track titles and similar.  There are three possibilities: Use an
external cue sheet that includes these information, use a tag CUESHEET
with a cue sheet including these information or use tags.  I think the
latter is the best option and is already used by other projects.

src/decoder/_flac_common.c

@@ -100,17 +100,25 @@ flac_parse_replay_gain(const FLAC__StreamMetadata *block,
  */
 static const char *
 flac_comment_value(const FLAC__StreamMetadata_VorbisComment_Entry *entry,
-		   const char *name, size_t *length_r)
+		   const char *name, const char *char_tnum, size_t *length_r)
 {
 	size_t name_length = strlen(name);
+	size_t char_tnum_length = strlen(char_tnum);
 	const char *comment = (const char*)entry->entry;
 
 	if (entry->length > name_length &&
-	    g_ascii_strncasecmp(comment, name, name_length) == 0 &&
+	    g_ascii_strncasecmp(comment, name, name_length) == 0) {
-	    comment[name_length] == '=') {
+	        if (char_tnum != NULL) {
+	            char_tnum_length = strlen(char_tnum);
+		    if (g_ascii_strncasecmp(comment + name_length,
+		        char_tnum, char_tnum_length) == 0)
+			    name_length = name_length + char_tnum_length;
+	        }
+	        if (comment[name_length] == '=') {
 		    *length_r = entry->length - name_length - 1;
 		    return comment + name_length + 1;
 		}
+	}
 
 	return NULL;
 }
@@ -122,12 +130,13 @@ flac_comment_value(const FLAC__StreamMetadata_VorbisComment_Entry *entry,
 static bool
 flac_copy_comment(struct tag *tag,
 		  const FLAC__StreamMetadata_VorbisComment_Entry *entry,
-		  const char *name, enum tag_type tag_type)
+		  const char *name, enum tag_type tag_type,
+		  const char *char_tnum)
 {
 	const char *value;
 	size_t value_length;
 
-	value = flac_comment_value(entry, name, &value_length);
+	value = flac_comment_value(entry, name, char_tnum, &value_length);
 	if (value != NULL) {
 		tag_add_item_n(tag, tag_type, value, value_length);
 		return true;
@@ -142,34 +151,34 @@ static const char *VORBIS_COMMENT_TRACK_KEY = "tracknumber";
 static const char *VORBIS_COMMENT_DISC_KEY = "discnumber";
 
 static void
-flac_parse_comment(struct tag *tag,
+flac_parse_comment(struct tag *tag, const char *char_tnum,
 		   const FLAC__StreamMetadata_VorbisComment_Entry *entry)
 {
 	assert(tag != NULL);
 
 	if (flac_copy_comment(tag, entry, VORBIS_COMMENT_TRACK_KEY,
-			      TAG_ITEM_TRACK) ||
+			      TAG_ITEM_TRACK, char_tnum) ||
 	    flac_copy_comment(tag, entry, VORBIS_COMMENT_DISC_KEY,
-			      TAG_ITEM_DISC) ||
+			      TAG_ITEM_DISC, char_tnum) ||
 	    flac_copy_comment(tag, entry, "album artist",
-			      TAG_ITEM_ALBUM_ARTIST))
+			      TAG_ITEM_ALBUM_ARTIST, char_tnum))
 		return;
 
 	for (unsigned i = 0; i < TAG_NUM_OF_ITEM_TYPES; ++i)
 		if (flac_copy_comment(tag, entry,
-				      tag_item_names[i], i))
+				      tag_item_names[i], i, char_tnum))
 			return;
 }
 
 void
-flac_vorbis_comments_to_tag(struct tag *tag,
+flac_vorbis_comments_to_tag(struct tag *tag, const char *char_tnum,
 			    const FLAC__StreamMetadata *block)
 {
 	FLAC__StreamMetadata_VorbisComment_Entry *comments =
 		block->data.vorbis_comment.comments;
 
 	for (unsigned i = block->data.vorbis_comment.num_comments; i > 0; --i)
-		flac_parse_comment(tag, comments++);
+		flac_parse_comment(tag, char_tnum, comments++);
 }
 
 void flac_metadata_common_cb(const FLAC__StreamMetadata * block,
@@ -188,7 +197,7 @@ void flac_metadata_common_cb(const FLAC__StreamMetadata * block,
 		flac_parse_replay_gain(block, data);
 
 		if (data->tag != NULL)
-			flac_vorbis_comments_to_tag(data->tag, block);
+			flac_vorbis_comments_to_tag(data->tag, NULL, block);
 
 	default:
 		break;

src/decoder/_flac_common.h

@@ -170,7 +170,7 @@ void flac_error_common_cb(const char *plugin,
 			  struct flac_data *data);
 
 void
-flac_vorbis_comments_to_tag(struct tag *tag,
+flac_vorbis_comments_to_tag(struct tag *tag, const char *char_tnum,
 			    const FLAC__StreamMetadata *block);
 
 FLAC__StreamDecoderWriteStatus

src/decoder/flac_plugin.c

@@ -227,7 +227,7 @@ flac_write_cb(const flac_decoder *dec, const FLAC__Frame *frame,
 }
 
 static struct tag *
-flac_tag_load(const char *file)
+flac_tag_load(const char *file, const char *char_tnum)
 {
 	struct tag *tag;
 	FLAC__Metadata_SimpleIterator *it;
@@ -265,7 +265,7 @@ flac_tag_load(const char *file)
 		if (!block)
 			break;
 		if (block->type == FLAC__METADATA_TYPE_VORBIS_COMMENT) {
-			flac_vorbis_comments_to_tag(tag, block);
+			flac_vorbis_comments_to_tag(tag, char_tnum, block);
 		} else if (block->type == FLAC__METADATA_TYPE_STREAMINFO) {
 			tag->time = ((float)block->data.stream_info.total_samples) /
 			    block->data.stream_info.sample_rate + 0.5;
@@ -298,13 +298,13 @@ flac_cue_tag_load(const char *file)
 	FLAC__StreamMetadata* cs = FLAC__metadata_object_new(FLAC__METADATA_TYPE_CUESHEET);
 
 	tnum = flac_vtrack_tnum(file);
+	char_tnum = g_strdup_printf("%u", tnum);
 
 	slash = strrchr(file, '/');
 	*slash = '\0';
 
-	tag = flac_tag_load(file);
+	tag = flac_tag_load(file, char_tnum);
 
-	char_tnum = g_strdup_printf("%u", tnum);
 	if (char_tnum != NULL)
 	{
 		tag_add_item(	tag,
@@ -350,7 +350,7 @@ flac_tag_dup(const char *file)
 		return flac_cue_tag_load(file);
 	else
 #endif /* FLAC_API_VERSION_CURRENT >= 7 */
-		return flac_tag_load(file);
+		return flac_tag_load(file, NULL);
 }
 
 static void
@@ -823,7 +823,7 @@ oggflac_tag_dup(const char *file)
 		if (!(block = FLAC__metadata_iterator_get_block(it)))
 			break;
 		if (block->type == FLAC__METADATA_TYPE_VORBIS_COMMENT) {
-			flac_vorbis_comments_to_tag(ret, block);
+			flac_vorbis_comments_to_tag(ret, NULL, block);
 		} else if (block->type == FLAC__METADATA_TYPE_STREAMINFO) {
 			ret->time = ((float)block->data.stream_info.
 				     total_samples) /

src/decoder/oggflac_plugin.c

@@ -180,7 +180,7 @@ static void of_metadata_dup_cb(G_GNUC_UNUSED const OggFLAC__SeekableStreamDecode
 		    block->data.stream_info.sample_rate + 0.5;
 		return;
 	case FLAC__METADATA_TYPE_VORBIS_COMMENT:
-		flac_vorbis_comments_to_tag(data->tag, block);
+		flac_vorbis_comments_to_tag(data->tag, NULL, block);
 	default:
 		break;
 	}