/*
* ID3 Tag identifier
* 04 00 2 bytes version
* xx Tag flags
* xx xx xx xx Tag size excluding header and footer as syncsafe int
* [Extended header]
* {Frames}
* [Padding]
* [Footer]
*/
private static void EncodeID3v2_4Tag(Stream s, ID3v2Tag tag)
{
byte flagByte = 0;
long paddingLen, size;
const long TagHeaderSize = 10L;
if ((tag.Flags & ID3v2TagFlags.Unsync) == ID3v2TagFlags.Unsync) {
flagByte |= 0x80;
}
if (tag.ExtendedHeader != null) {
flagByte |= 0x40;
}
if ((tag.Flags & ID3v2TagFlags.Experimental) == ID3v2TagFlags.Experimental) {
flagByte |= 0x20;
}
if ((tag.Flags & ID3v2TagFlags.Footer) == ID3v2TagFlags.Footer) {
flagByte |= 0x10;
}
StringEncoder.WriteLatin1String(s, "ID3", 3);
s.WriteByte(0x04);
s.WriteByte(0x00);
s.WriteByte(flagByte);
/* skip size */
s.Position += 4;
if (tag.ExtendedHeader != null) {
byte[] frameData = GetFrameRawData(tag);
long crc = -1L;
if ((tag.ExtendedHeader.Flags & ExtendedHeaderFlags.CrcPresent) == ExtendedHeaderFlags.CrcPresent) {
/* CRC is calculated on frame data and padding */
Crc32 crcCalc = new Crc32();
crcCalc.UpdateCrc(frameData);
crcCalc.UpdateCrcWithZero(ComputePaddingSize(frameData.Length + TagHeaderSize, tag));
crc = crcCalc.Crc;
}
EncodeID3v2_4ExtendedHeader(s, tag.ExtendedHeader, crc);
s.Write(frameData, 0, frameData.Length);
} else {
foreach (Frame f in tag.Frames) {
FrameEncoder.EncodeFrame(s, f, tag);
}
}
paddingLen = ComputePaddingSize(s.Length, tag);
s.SetLength(s.Length + paddingLen);
size = s.Length - TagHeaderSize;
if ((tag.Flags & ID3v2TagFlags.Footer) == ID3v2TagFlags.Footer) {
s.Position = s.Length - 1L;
StringEncoder.WriteLatin1String(s, "3DI", 3);
s.WriteByte(0x04);
s.WriteByte(0x00);
s.WriteByte(flagByte);
NumberConverter.WriteInt(size, s, 4, true);
}
s.Position = 6L;
NumberConverter.WriteInt(size, s, 4, true);
}
