// extractID3 attempts to extract MusicBrainz Picard tags from m.Raw(), where m.Format
// is assumed to be a supported version of ID3.
func extractID3(m tag.Metadata) Info {
var txxx, ufid string
switch m.Format() {
case tag.ID3v2_2:
txxx, ufid = "TXX", "UFI"
case tag.ID3v2_3, tag.ID3v2_4:
txxx, ufid = "TXXX", "UFID"
}
i := Info{}
for k, v := range m.Raw() {
switch {
case strings.HasPrefix(k, txxx):
if str, ok := v.(*tag.Comm); ok {
i.set(str.Description, str.Text)
}
case strings.HasPrefix(k, ufid):
if id, ok := v.(*tag.UFID); ok {
if id.Provider == UFIDProviderURL {
i.set(Recording, string(id.Identifier))
}
}
}
}
return i
}
// extractMP4Vorbis attempts to extract MusicBrainz Picard tags from m.Raw(), where m.Format
// is assumed to be MP4 or VORBIS.
func extractMP4Vorbis(m tag.Metadata) Info {
i := Info{}
for t, v := range m.Raw() {
if s, ok := v.(string); ok {
i.set(t, s)
}
}
return i
}