/*
* xx xx xx xx Extended Header size, excluding itself; currently 6 or 10 bytes; not sync safe.
* xx xx Flags
* xx xx xx xx Size of padding; not sync safe
* [xx xx xx xx] 4 bytes of CRC Data; not sync safe
*
*/
private static void EncodeID3v2_3ExtendedHeader(Stream s, ExtendedHeader extHeader, long paddingLen, long crc)
{
bool writeCRCData = ((extHeader.Flags & ExtendedHeaderFlags.CrcPresent) == ExtendedHeaderFlags.CrcPresent);
int size = (writeCRCData ? 10 : 6);
NumberConverter.WriteInt(size, s, 4, false);
s.WriteByte((writeCRCData ? (byte)0x80 : (byte)0x00));
s.WriteByte(0x00);
NumberConverter.WriteInt(paddingLen, s, 4, false);
if (writeCRCData) {
NumberConverter.WriteInt(crc, s, 4, false);
/* update crc checksum in extended header */
extHeader.CrcChecksum = crc;
}
}
/*
* xx xx xx xx Extended header size(min 6) as syncsafe int
* xx Number of flag bytes(currently 1)
* xx Flags
* {sizeByte [flagdata]} For every set bit in flag one entry
*
*/
private static void EncodeID3v2_4ExtendedHeader(Stream s, ExtendedHeader extHeader, long crc)
{
int size = 6;
byte flagByte = 0;
/* compute flag byte */
if ((extHeader.Flags & ExtendedHeaderFlags.UpdateTag) == ExtendedHeaderFlags.UpdateTag) {
flagByte |= 0x40;
size += 1;
}
if ((extHeader.Flags & ExtendedHeaderFlags.CrcPresent) == ExtendedHeaderFlags.CrcPresent) {
flagByte |= 0x20;
size += 6;
}
if ((extHeader.Flags & ExtendedHeaderFlags.RestrictTag) == ExtendedHeaderFlags.RestrictTag) {
flagByte |= 0x10;
size += 2;
}
/* write Header */
NumberConverter.WriteInt(size, s, 4, true);
s.WriteByte(0x01);
s.WriteByte(flagByte);
/* write attached data */
if ((extHeader.Flags & ExtendedHeaderFlags.UpdateTag) != 0) {
s.WriteByte(0x00);
}
if ((extHeader.Flags & ExtendedHeaderFlags.CrcPresent) != 0) {
s.WriteByte(0x05);
NumberConverter.WriteInt(crc, s, 5, true);
/* update crc checksum in extended header */
extHeader.CrcChecksum = crc;
}
if ((extHeader.Flags & ExtendedHeaderFlags.RestrictTag) != 0) {
byte restrictFlagByte = 0;
restrictFlagByte |= (byte)extHeader.TagSizeRestriction;
restrictFlagByte |= (byte)extHeader.TextEncodingRestriction;
restrictFlagByte |= (byte)extHeader.TextFieldSizeRestriction;
restrictFlagByte |= (byte)extHeader.TextFieldSizeRestriction;
restrictFlagByte |= (byte)extHeader.ImageEncodingRestriction;
restrictFlagByte |= (byte)extHeader.ImageSizeRestriction;
s.WriteByte(0x01);
s.WriteByte(restrictFlagByte);
}
}
/*
* xx xx xx xx Extended header size(min 6) as syncsafe int
* xx Number of flag bytes(currently 1)
* xx Flags
* {sizeByte [flagdata]} For every set bit in flag one entry
*
*/
private static int DecodeID3v2_4ExtendedHeader(byte[] tagContent, ExtendedHeader extHeader)
{
int extHeaderSize, index;
CheckLength(tagContent, 6);
extHeaderSize = NumberConverter.ReadInt32(tagContent, 0, 4, true);
if (extHeaderSize < 6) {
throw new ID3ParseException("Size mismatch in extended header.");
}
if (tagContent[4] != 0x01) {
throw new ID3ParseException("Flag byte count in extended header does not match.");
}
CheckLength(tagContent, extHeaderSize);
/* parse extended header flags */
extHeader.Flags = ExtendedHeaderFlags.None;
index = 6;
if ((tagContent[5] & 0x40) != 0) {
extHeader.Flags |= ExtendedHeaderFlags.UpdateTag;
if (index >= extHeaderSize || tagContent[index] != 0x00) {
throw new ID3ParseException("Error while parsing extended header flag data.");
}
index += 1;
}
if ((tagContent[5] & 0x20) != 0) {
extHeader.Flags |= ExtendedHeaderFlags.CrcPresent;
if (index + 5 >= extHeaderSize || tagContent[index] != 0x05) {
throw new ID3ParseException("Error while parsing extended header flag data.");
}
long savedCrc = NumberConverter.ReadInt64(tagContent, index + 1, 5, true);
Crc32 crcCalculator = new Crc32();
crcCalculator.UpdateCrc(tagContent, extHeaderSize, tagContent.Length - extHeaderSize);
if (savedCrc != crcCalculator.Crc) {
throw new ID3CrcMismatchException(savedCrc, crcCalculator.Crc);
}
extHeader.CrcChecksum = savedCrc;
index += 6;
}
if ((tagContent[5] & 0x10) != 0) {
extHeader.Flags |= ExtendedHeaderFlags.RestrictTag;
if (index + 1 >= extHeaderSize || tagContent[index] != 0x01) {
throw new ID3ParseException("Error while parsing extended header flag data.");
}
index += 1;
extHeader.TagSizeRestriction = (TagSizeRestriction)(tagContent[index] & 0xC0);
extHeader.TextEncodingRestriction = (TextEncodingRestriction)(tagContent[index] & 0x20);
extHeader.TextFieldSizeRestriction = (TextFieldSizeRestriction)(tagContent[index] & 0x18);
extHeader.ImageEncodingRestriction = (ImageEncodingRestriction)(tagContent[index] & 0x4);
extHeader.ImageSizeRestriction = (ImageSizeRestriction)(tagContent[index] & 0x3);
index += 1;
}
if ((tagContent[5] & 0x8F) != 0) {
throw new ID3ParseException("Invalid entended header flag set.");
}
if (index != extHeaderSize) {
throw new ID3ParseException("Size mismatch in extended header.");
}
return extHeaderSize;
}
public bool Equals(ExtendedHeader other)
{
if (other == null) {
return false;
}
if (flags != other.flags) {
return false;
}
if ((flags & ExtendedHeaderFlags.CrcPresent) == ExtendedHeaderFlags.CrcPresent && crcChecksum != other.crcChecksum) {
return false;
}
if ((flags & ExtendedHeaderFlags.RestrictTag) == ExtendedHeaderFlags.RestrictTag) {
if (textEncodingRestriction != other.textEncodingRestriction ||
tagSizeRestriction != other.tagSizeRestriction ||
textFieldSizeRestriction != other.textFieldSizeRestriction ||
imageEncodingRestriction != other.imageEncodingRestriction ||
imageSizeRestriction != other.imageSizeRestriction) {
return false;
}
}
return true;
}
/*
* xx xx xx xx Extended Header size, excluding itself; currently 6 or 10 bytes; not sync safe.
* xx xx Flags
* xx xx xx xx Size of padding; not sync safe
* [xx xx xx xx] 4 bytes of CRC Data; not sync safe
*
*/
private static int DecodeID3v2_3ExtendedHeader(byte[] tagContent, ExtendedHeader extHeader)
{
int extHeaderSize, paddingSize;
CheckLength(tagContent, 10);
extHeaderSize = NumberConverter.ReadInt32(tagContent, 0, 4, false);
paddingSize = NumberConverter.ReadInt32(tagContent, 6, 4, false);
if ((tagContent[4] & 0x7F) != 0 || tagContent[5] != 0x00) {
throw new ID3ParseException("Unknown extended header flag set.");
}
if (tagContent[4] == 0x80) {
extHeader.Flags = ExtendedHeaderFlags.CrcPresent;
if (extHeaderSize != 10) {
throw new ID3ParseException("Invalid extended header size.");
}
CheckLength(tagContent, 14);
long savedCrc = NumberConverter.ReadInt64(tagContent, 10, 4, false);
int dataLength = tagContent.Length - 14 - paddingSize;
Crc32 crcCalculator = new Crc32();
if (dataLength < 0) {
throw new ID3ParseException("Padding size mismatch in extended header.");
}
crcCalculator.UpdateCrc(tagContent, 14, dataLength);
if (savedCrc != crcCalculator.Crc) {
throw new ID3CrcMismatchException(savedCrc, crcCalculator.Crc);
}
extHeader.CrcChecksum = savedCrc;
} else {
extHeader.Flags = ExtendedHeaderFlags.None;
if (extHeaderSize != 6) {
throw new ID3ParseException("Invalid extended header size.");
}
}
return extHeaderSize;
}
