func (editor *Mp3TagEditor) getUnsupportedID3v2Tags(existingTagData []byte) []byte {
result := make([]byte, len(existingTagData))
size := 0
for len(existingTagData) > id3v2FrameHeaderSize {
frameId := string(existingTagData[0:4])
frameSize := utils.ReadInt32Be(existingTagData[4:8])
stop := false
switch frameId {
case "\x00\x00\x00\x00":
stop = true
case "APIC", "COMM", "TALB", "TCON", "TIT2", "TPE1", "TRCK", "TYER", "TDRC":
break
default:
copy(result[size:size+id3v2FrameHeaderSize+frameSize], existingTagData[:id3v2FrameHeaderSize+frameSize])
size += id3v2FrameHeaderSize + frameSize
}
if stop {
break
}
existingTagData = existingTagData[id3v2FrameHeaderSize+frameSize:]
}
return result[:size]
}
func (editor *Mp3TagEditor) findIDv2Data(version byte, data []byte) []byte {
if len(data) < id3v2HeaderSize {
return nil
}
if string(data[0:3]) != id3v2TagMagic {
return nil
}
size := editor.readSyncInt32Be(data[6:10])
if len(data) < id3v2HeaderSize+size || size == 0 {
return nil
}
// wrong version, continue search
if data[3] != version || data[4] != 0 {
return editor.findIDv2Data(version, data[(id3v2HeaderSize+size):])
}
// exclude extended header if any
extendedHeaderSize := 0
if data[5]&0x40 != 0 {
switch version {
case 3:
extendedHeaderSize = utils.ReadInt32Be(data[11:15]) + 4
case 4:
extendedHeaderSize = editor.readSyncInt32Be(data[11:15])
}
}
return data[(id3v2HeaderSize + extendedHeaderSize):(id3v2HeaderSize + extendedHeaderSize + size)]
}
func (editor *Mp3TagEditor) parseID3v2Tag(data []byte, version int) Tag {
if len(data) == 0 {
return Tag{}
}
var tag Tag
for len(data) > id3v2FrameHeaderSize {
frameId := string(data[0:4])
if frameId == "\x00\x00\x00\x00" {
break
}
frameSize := 0
switch version {
case 3:
frameSize = utils.ReadInt32Be(data[4:8])
case 4:
frameSize = editor.readSyncInt32Be(data[4:8])
}
editor.parseID3v2Frame(&tag, frameId, data[id3v2FrameHeaderSize:(id3v2FrameHeaderSize+frameSize)])
data = data[id3v2FrameHeaderSize+frameSize:]
}
return tag
}
func parseVorbisTagPictureField(data []byte, cover *Cover) error {
if len(data) < 4 {
return errors.New("vorbis picture data is too short to contain a picture")
}
cover.Type = imageType[byte(utils.ReadInt32Be(data[0:4]))]
mimeTypeSize := utils.ReadInt32Be(data[4:8])
if len(data) < 8+mimeTypeSize+4 {
return errors.New("vorbis picture data is incomplete")
}
cover.Mime = string(data[8 : 8+mimeTypeSize])
descriptionSize := utils.ReadInt32Be(data[8+mimeTypeSize : 8+mimeTypeSize+4])
if len(data) < 8+mimeTypeSize+4+descriptionSize+20 {
return errors.New("vorbis picture data is incomplete")
}
cover.Description = string(data[8+mimeTypeSize+4 : 8+mimeTypeSize+4+descriptionSize])
cover.Data = make([]byte, len(data)-(8+mimeTypeSize+4+descriptionSize+20))
copy(cover.Data, data[8+mimeTypeSize+4+descriptionSize+20:])
return nil
}