///
/// Reads a subset of the id3 information
///
public ID3v2( string path, bool verboseDump )
{
_debugDump = verboseDump;
_stream = new FileStream( path,
FileMode.Open,
FileAccess.Read,
FileShare.Read );
_reader = new Mp3StreamReader( _stream );
try
{
// Find the start of the ID3v2 tag in our stream:
_header = _FindHeader( false );
Debug.Assert( null != _header );
if (_debugDump)
{
_Trace( " isValid: " + _header.isValid );
_Trace( " version: " + _header.version );
_Trace( " flags: " + _header.flags );
_Trace( " isUnsynchronized: " + _header.isUnsynchronized );
_Trace( " hasExtendedHeader: " + _header.hasExtendedHeader );
_Trace( " isExperimental: " + _header.isExperimental );
_Trace( " hasFooter: " + _header.hasFooter );
_Trace( " size: " + _header.size );
}
if (_header.isUnsynchronized)
{
throw new ApplicationException(
"Sorry, whole-tag unsynchronization not yet implemented" );
}
// For now, forget about it
_SkipExtendedHeader(); // skip to the meat
// Finally, start looking for interesting information in the
// stream.
_ReadFrames();
}
catch (ID3TagNotFoundException nfe)
{
_header = null; // not found. Boo!
}
finally
{
_reader = null;
_stream.Close();
_stream = null;
}
}
///
/// \param tryTheEnd - if false, we only look in the first 3 bytes
/// for a header.
///
ID3v2Header _FindHeader( bool tryTheEnd )
{
// look for the tag at the start or end of the file. If it's
// somewhere in the middle, forget it.
/// \bug We should be ready to deal with id3 tags in the middle
/// of the file, but this isn't very likely, so...
// From the FAQ:
// # Q: Where is an ID3v2 tag located in an MP3 file?
// It is most likely located at the beginning of the file.
//
// Look for the marker "ID3" in the first 3 bytes of the file.
//
// If it's not there, it could be at the end of the file
// (if the tag is ID3v2.4). Look for the marker "3DI" 10
// bytes from the end of the file, or 10 bytes before the
// beginning of an ID3v1 tag.
//
// Finally it is possible to embed ID3v2 tags in the actual
// MPEG stream, on an MPEG frame boundry. Almost nobody does
// this.
//
// Try the start
byte [] buffer = new byte[10];
_reader.Read( buffer, 10 ); // get the file header
ID3v2Header header = new ID3v2Header( buffer, true );
if (header.isValid)
{
if (_debugDump)
_Trace( " Found header at start" );
return header;
}
if (!tryTheEnd)
{
/// \todo search for id3v2 tag in the middle of the file
///
throw new ID3TagNotFoundException();
}
// Seek to end of file (new for 2.4)
_Trace( "FIXME: look for ID3v2.4 tag at EOF" );
throw new ID3TagNotFoundException();
}
