private byte[] FindHeader()
{
byte thisByte = br.ReadByte();
while (br.BaseStream.Position < br.BaseStream.Length)
{
if (System.Convert.ToInt32(thisByte) == 255)
{
bool[] thatByte = BitReader.ToBitBool(br.ReadByte());
br.BaseStream.Position--;
if (thatByte[0] && thatByte[1] && thatByte[2])
{
// we found the sync.
this.headerPosition = br.BaseStream.Position - 1;
byte [] retByte = new byte [4];
retByte[0] = thisByte;
retByte[1] = br.ReadByte();
retByte[2] = br.ReadByte();
retByte[3] = br.ReadByte();
return(retByte);
}
else
{
thisByte = br.ReadByte();
}
}
else
{
thisByte = br.ReadByte();
}
}
return(null);
}
public id3v2Frame ReadFrame(BinaryReader br, int version)
{
char[] tagSize; // I use this to read the bytes in from the file
int[] bytes; // for bit shifting
ulong newSize = 0; // for the final number
int nameSize = 4;
if (version == 2)
{
nameSize = 3;
}
else if ((version == 3) || (version == 4))
{
nameSize = 4;
}
id3v2Frame f1 = new id3v2Frame();
f1.frameName = new string (br.ReadChars(nameSize));
f1.MajorVersion = version;
// in order to check for padding I have to build a string of 4 (or 3 if v2.2) null bytes
// there must be a better way to do this
char nullChar = System.Convert.ToChar(0);
StringBuilder sb = new StringBuilder(0, nameSize);
sb.Append(nullChar);
sb.Append(nullChar);
sb.Append(nullChar);
if (nameSize == 4)
{
sb.Append(nullChar);
}
if (f1.frameName == sb.ToString())
{
f1.padding = true;
return(f1);
}
if (version == 2)
{
// only have 3 bytes for size ;
tagSize = br.ReadChars(3); // I use this to read the bytes in from the file
bytes = new int[3]; // for bit shifting
newSize = 0; // for the final number
// The ID3v2 tag size is encoded with four bytes
// where the most significant bit (bit 7)
// is set to zero in every byte,
// making a total of 28 bits.
// The zeroed bits are ignored
//
// Some bit grinding is necessary. Hang on.
bytes[3] = tagSize[2] | ((tagSize[1] & 1) << 7);
bytes[2] = ((tagSize[1] >> 1) & 63) | ((tagSize[0] & 3) << 6);
bytes[1] = ((tagSize[0] >> 2) & 31);
newSize = ((UInt64)bytes[3] |
((UInt64)bytes[2] << 8) |
((UInt64)bytes[1] << 16));
//End Dan Code
}
else if (version == 3 || version == 4)
{
// version 2.4
tagSize = br.ReadChars(4); // I use this to read the bytes in from the file
bytes = new int[4]; // for bit shifting
newSize = 0; // for the final number
// The ID3v2 tag size is encoded with four bytes
// where the most significant bit (bit 7)
// is set to zero in every byte,
// making a total of 28 bits.
// The zeroed bits are ignored
//
// Some bit grinding is necessary. Hang on.
bytes[3] = tagSize[3] | ((tagSize[2] & 1) << 7);
bytes[2] = ((tagSize[2] >> 1) & 63) | ((tagSize[1] & 3) << 6);
bytes[1] = ((tagSize[1] >> 2) & 31) | ((tagSize[0] & 7) << 5);
bytes[0] = ((tagSize[0] >> 3) & 15);
newSize = ((UInt64)bytes[3] |
((UInt64)bytes[2] << 8) |
((UInt64)bytes[1] << 16) |
((UInt64)bytes[0] << 24));
//End Dan Code
}
f1.frameSize = newSize;
if (version > 2)
{
// versions 3+ have frame tags.
if (version == 3)
{
bool [] c;
// read teh tags
c = BitReader.ToBitBool(br.ReadByte());
f1.F_TagAlterPreservation = c[0];
f1.F_FileAlterPreservation = c[1];
f1.F_ReadOnly = c[2];
c = BitReader.ToBitBool(br.ReadByte());
f1.F_Compression = c[0];
f1.F_Encryption = c[1];
f1.F_GroupingIdentity = c[2];
}
else if (version == 4)
{
//%0abc0000 %0h00kmnp
//a - Tag alter preservation
// 0 Frame should be preserved.
// 1 Frame should be discarded.
// b - File alter preservation
// 0 Frame should be preserved.
//1 Frame should be discarded.
// c - Read only
// h - Grouping identity
// 0 Frame does not contain group information
// 1 Frame contains group information
// k - Compression
// 0 Frame is not compressed.
// 1 Frame is compressed using zlib [zlib] deflate method.
// If set, this requires the 'Data Length Indicator' bit
// to be set as well.
// m - Encryption
// 0 Frame is not encrypted.
// 1 Frame is encrypted.
// n - Unsynchronisation
// 0 Frame has not been unsynchronised.
// 1 Frame has been unsyrchronised.
// p - Data length indicator
// 0 There is no Data Length Indicator.
// 1 A data length Indicator has been added to the frame.
bool [] c;
// read teh tags
c = BitReader.ToBitBool(br.ReadByte());
f1.F_TagAlterPreservation = c[1];
f1.F_FileAlterPreservation = c[2];
f1.F_ReadOnly = c[3];
c = BitReader.ToBitBool(br.ReadByte());
f1.F_GroupingIdentity = c[1];
f1.F_Compression = c[4];
f1.F_Encryption = c[5];
f1.F_Unsynchronisation = c[6];
f1.F_DataLengthIndicator = c[7];
}
if (f1.frameSize > 0)
{
f1.frameContents = br.ReadBytes((int)f1.frameSize);
}
}
return(f1);
}
private void ReadFooter()
{
// bring in the first three bytes. it must be ID3 or we have no tag
// TODO add logic to check the end of the file for "3D1" and other
// possible starting spots
string id3start = new string (br.ReadChars(3));
// check for a tag
if (!id3start.Equals("3DI"))
{
// TODO we are f****d. not really we just don't ahve a tag
// and we need to bail out gracefully.
//throw id3v23ReaderException;
}
else
{
// we have a tag
this.hasTag = true;
}
// read id3 version. 2 bytes:
// The first byte of ID3v2 version is it's major version,
// while the second byte is its revision number
this.MajorVersion = System.Convert.ToInt32(br.ReadByte());
this.MinorVersion = System.Convert.ToInt32(br.ReadByte());
// here is where we get fancy. I am useing silisoft's php code as
// a reference here. we are going to try and parse for 2.2, 2.3 and 2.4
// in one pass. hold on!!
if ((this.hasTag) && (this.MajorVersion <= 4)) // probably won't work on higher versions
{
// (%ab000000 in v2.2, %abc00000 in v2.3, %abcd0000 in v2.4.x)
//read next byte for flags
bool [] boolar = BitReader.ToBitBool(br.ReadByte());
// set the flags
if (this.MajorVersion == 2)
{
this.FA_Unsynchronisation = boolar[0];
this.FB_ExtendedHeader = boolar[1];
}
else if (this.MajorVersion == 3)
{
// set the flags
this.FA_Unsynchronisation = boolar[0];
this.FB_ExtendedHeader = boolar[1];
this.FC_ExperimentalIndicator = boolar[2];
}
else if (this.MajorVersion == 4)
{
// set the flags
this.FA_Unsynchronisation = boolar[0];
this.FB_ExtendedHeader = boolar[1];
this.FC_ExperimentalIndicator = boolar[2];
this.FD_Footer = boolar[3];
}
// read teh size
// this code is courtesy of Daniel E. White w/ minor modifications by me Thanx Dan
//Dan Code
char[] tagSize = br.ReadChars(4); // I use this to read the bytes in from the file
int[] bytes = new int[4]; // for bit shifting
ulong newSize = 0; // for the final number
// The ID3v2 tag size is encoded with four bytes
// where the most significant bit (bit 7)
// is set to zero in every byte,
// making a total of 28 bits.
// The zeroed bits are ignored
//
// Some bit grinding is necessary. Hang on.
bytes[3] = tagSize[3] | ((tagSize[2] & 1) << 7);
bytes[2] = ((tagSize[2] >> 1) & 63) | ((tagSize[1] & 3) << 6);
bytes[1] = ((tagSize[1] >> 2) & 31) | ((tagSize[0] & 7) << 5);
bytes[0] = ((tagSize[0] >> 3) & 15);
newSize = ((UInt64)10 + (UInt64)bytes[3] |
((UInt64)bytes[2] << 8) |
((UInt64)bytes[1] << 16) |
((UInt64)bytes[0] << 24));
//End Dan Code
this.headerSize = newSize;
}
}
private void ReadHeader( )
{
// bring in the first three bytes. it must be ID3 or we have no tag
// TODO add logic to check the end of the file for "3D1" and other
// possible starting spots
string id3start = new string (br.ReadChars(3));
// check for a tag
if (!id3start.Equals("ID3"))
{
// TODO we are f****d.
//throw id3v2ReaderException;
this.hasTag = false;
return;
}
else
{
this.hasTag = true;
// read id3 version. 2 bytes:
// The first byte of ID3v2 version is it's major version,
// while the second byte is its revision number
this.MajorVersion = System.Convert.ToInt32(br.ReadByte());
this.MinorVersion = System.Convert.ToInt32(br.ReadByte());
//read next byte for flags
bool [] boolar = BitReader.ToBitBool(br.ReadByte());
// set the flags
this.FA_Unsynchronisation = boolar[0];
this.FB_ExtendedHeader = boolar[1];
this.FC_ExperimentalIndicator = boolar[2];
// read teh size
// this code is courtesy of Daniel E. White w/ minor modifications by me Thanx Dan
//Dan Code
char[] tagSize = br.ReadChars(4); // I use this to read the bytes in from the file
int[] bytes = new int[4]; // for bit shifting
ulong newSize = 0; // for the final number
// The ID3v2 tag size is encoded with four bytes
// where the most significant bit (bit 7)
// is set to zero in every byte,
// making a total of 28 bits.
// The zeroed bits are ignored
//
// Some bit grinding is necessary. Hang on.
bytes[3] = tagSize[3] | ((tagSize[2] & 1) << 7);
bytes[2] = ((tagSize[2] >> 1) & 63) | ((tagSize[1] & 3) << 6);
bytes[1] = ((tagSize[1] >> 2) & 31) | ((tagSize[0] & 7) << 5);
bytes[0] = ((tagSize[0] >> 3) & 15);
newSize = ((UInt64)10 + (UInt64)bytes[3] |
((UInt64)bytes[2] << 8) |
((UInt64)bytes[1] << 16) |
((UInt64)bytes[0] << 24));
//End Dan Code
this.headerSize = newSize;
}
}