internal static byte[] ApplyUnsynchronization(byte[] data)
{
MemoryStream ms = new MemoryStream(data.Length * 2);
UnsyncFilterStream fs = new UnsyncFilterStream(ms, UnsyncMode.Write, true);
fs.Write(data, 0, data.Length);
fs.ApplyFinalization();
ms.Close();
return ms.ToArray();
}
internal static byte[] RemoveUnsynchronization(byte[] data)
{
MemoryStream ms = new MemoryStream(data, false);
UnsyncFilterStream fs = new UnsyncFilterStream(ms, UnsyncMode.Read, true);
byte[] synchronizedData = new byte[data.Length];
int bytesRead;
bytesRead = fs.Read(synchronizedData, 0, synchronizedData.Length);
// can be == or less
if (bytesRead < synchronizedData.Length) {
byte[] tmp = new byte[bytesRead];
Buffer.BlockCopy(synchronizedData, 0, tmp, 0, bytesRead);
synchronizedData = tmp;
}
return synchronizedData;
}
private static void WriteContentToStream(Stream s, ID3v2Tag tag)
{
if ((tag.Flags & ID3v2TagFlags.Unsync) == ID3v2TagFlags.Unsync) {
UnsyncFilterStream unsyncFilterStream = new UnsyncFilterStream(s, UnsyncMode.Write, true);
foreach (Frame f in tag.Frames) {
FrameEncoder.EncodeFrame(unsyncFilterStream, f, tag);
}
unsyncFilterStream.ApplyFinalization();
} else {
foreach (Frame f in tag.Frames) {
FrameEncoder.EncodeFrame(s, f, tag);
}
}
}
/*
* ID3 Tag Identifier
* 03 00 2 bytes Version information
* xx Tag flags
* xx xx xx xx Tag size excluding header but including extended header as sync safe integer
* [Extended header]
* {Frames}
* [Padding] included in tag size
*
* Note: Unsync is applied on tag level; footer is not allowed.
*
*/
private static void EncodeID3v2_3Tag(Stream s, ID3v2Tag tag)
{
long paddingLen;
byte flags = 0;
const long TagHeaderSize = 10L;
const long ExtHeaderSizeWithCrc = 14L;
const long ExtHeaderSizeWithoutCrc = 10L;
/* generate flag byte */
if ((tag.Flags & ID3v2TagFlags.Unsync) == ID3v2TagFlags.Unsync) {
flags |= 0x80;
}
if (tag.ExtendedHeader != null) {
flags |= 0x40;
}
if ((tag.Flags & ID3v2TagFlags.Experimental) == ID3v2TagFlags.Experimental) {
flags |= 0x20;
}
/* write tag header */
StringEncoder.WriteLatin1String(s, "ID3", 3);
s.WriteByte(0x03);
s.WriteByte(0x00);
s.WriteByte(flags);
/* skip size */
s.Position += 4;
if (tag.ExtendedHeader != null) {
long crc;
byte[] frameData = GetFrameRawData(tag);
if ((tag.ExtendedHeader.Flags & ExtendedHeaderFlags.CrcPresent) == ExtendedHeaderFlags.CrcPresent) {
crc = Crc32.ComputeCrc(frameData);
paddingLen = ComputePaddingSize(frameData.Length + TagHeaderSize + ExtHeaderSizeWithCrc, tag);
} else {
crc = -1L;
paddingLen = ComputePaddingSize(frameData.Length + TagHeaderSize + ExtHeaderSizeWithoutCrc, tag);
}
if ((tag.Flags & ID3v2TagFlags.Unsync) == ID3v2TagFlags.Unsync) {
UnsyncFilterStream unsyncFilterStream = new UnsyncFilterStream(s, UnsyncMode.Write, true);
EncodeID3v2_3ExtendedHeader(unsyncFilterStream, tag.ExtendedHeader, paddingLen, crc);
unsyncFilterStream.Write(frameData, 0, frameData.Length);
unsyncFilterStream.ApplyFinalization();
} else {
EncodeID3v2_3ExtendedHeader(s, tag.ExtendedHeader, paddingLen, crc);
s.Write(frameData, 0, frameData.Length);
}
} else {
/* no extended header */
WriteContentToStream(s, tag);
paddingLen = ComputePaddingSize(s.Length, tag);
}
/* update tag size */
s.SetLength(s.Length + paddingLen);
s.Position = 6;
NumberConverter.WriteInt(s.Length - TagHeaderSize, s, 4, true);
}
