public static Id3v2Frame CreateFrame(ByteVector data, uint version)
{
Id3v2FrameHeader header = new Id3v2FrameHeader(data, version);
ByteVector frameId = header.FrameId;
// A quick sanity check -- make sure that the frameId is 4 uppercase
// Latin1 characters. Also make sure that there is data in the frame.
if (frameId == null || frameId.Count != (version < 3 ? 3 : 4) || header.FrameSize < 0)
{
return(null);
}
foreach (byte b in frameId)
{
char c = (char)b;
if ((c < 'A' || c > 'Z') && (c < '1' || c > '9'))
{
return(null);
}
}
// Windows Media Player may create zero byte frames. Just send them
// off as unknown.
if (header.FrameSize == 0)
{
return(new Id3v2UnknownFrame(data, header));
}
// TagLib doesn'type mess with encrypted frames, so just treat them
// as unknown frames.
if (header.Compression)
{
TagLibDebugger.Debug("Compressed frames are currently not supported.");
return(new Id3v2UnknownFrame(data, header));
}
if (header.Encryption)
{
TagLibDebugger.Debug("Encrypted frames are currently not supported.");
return(new Id3v2UnknownFrame(data, header));
}
if (!UpdateFrame(header))
{
header.TagAlterPreservation = true;
return(new Id3v2UnknownFrame(data, header));
}
foreach (FrameCreator creator in frameCreators)
{
Id3v2Frame frame = creator(data, header);
if (frame != null)
{
return(frame);
}
}
// UpdateFrame() might have updated the frame ID.
frameId = header.FrameId;
// This is where things get necissarily nasty. Here we determine which
// Frame subclass (or if none is found simply an Frame) based
// on the frame ID. Since there are a lot of possibilities, that means
// a lot of if blocks.
// Text Identification (frames 4.2)
if (frameId.StartsWith("T"))
{
Id3v2TextIdentificationFrame frame = frameId != "TXXX"
? new Id3v2TextIdentificationFrame(data, header)
: new Id3v2UserTextIdentificationFrame(data, header);
if (useDefaultEncoding)
{
frame.TextEncoding = defaultEncoding;
}
return(frame);
}
// Comments (frames 4.10)
if (frameId == "COMM")
{
Id3v2CommentsFrame frame = new Id3v2CommentsFrame(data, header);
if (useDefaultEncoding)
{
frame.TextEncoding = defaultEncoding;
}
return(frame);
}
// Attached Picture (frames 4.14)
if (frameId == "APIC")
{
Id3v2AttachedPictureFrame f = new Id3v2AttachedPictureFrame(data, header);
if (useDefaultEncoding)
{
f.TextEncoding = defaultEncoding;
}
return(f);
}
// Relative Volume Adjustment (frames 4.11)
if (frameId == "RVA2")
{
return(new Id3v2RelativeVolumeFrame(data, header));
}
// Unique File Identifier (frames 4.1)
if (frameId == "UFID")
{
return(new Id3v2UniqueFileIdentifierFrame(data, header));
}
// Private (frames 4.27)
if (frameId == "PRIV")
{
return(new Id3v2PrivateFrame(data, header));
}
return(new Id3v2UnknownFrame(data, header));
}
private void Scan()
{
// Scan the metadata pages
if (scanned || !IsValid)
{
return;
}
uint ipacket = 0;
long overhead = 0;
ByteVector metadata_header = GetPacket(ipacket++);
if (metadata_header == null)
{
return;
}
ByteVector header;
if (!metadata_header.StartsWith("fLaC"))
{
// FLAC 1.1.2+
if (metadata_header.Mid(1, 4) != "FLAC")
{
return;
}
if (metadata_header[5] != 1)
{
return; // not version 1
}
metadata_header = metadata_header.Mid(13);
}
else
{
// FLAC 1.1.0 & 1.1.1
metadata_header = GetPacket(ipacket++);
if (metadata_header == null)
{
return;
}
}
header = metadata_header.Mid(0, 4);
// Header format (from spec):
// <1> Last-metadata-block flag
// <7> BLOCK_TYPE
// 0 : STREAMINFO
// 1 : PADDING
// ..
// 4 : VORBIS_COMMENT
// ..
// <24> Length of metadata to follow
byte block_type = (byte)(header[0] & 0x7f);
bool last_block = (header[0] & 0x80) != 0;
uint length = header.Mid(1, 3).ToUInt();
overhead += length;
// Sanity: First block should be the stream_info metadata
if (block_type != 0)
{
TagLibDebugger.Debug("Ogg.Flac.File.Scan() -- Invalid Ogg/FLAC stream");
return;
}
stream_info_data = metadata_header.Mid(4, (int)length);
// Search through the remaining metadata
while (!last_block)
{
metadata_header = GetPacket(ipacket++);
if (metadata_header == null)
{
return;
}
header = metadata_header.Mid(0, 4);
block_type = (byte)(header[0] & 0x7f);
last_block = (header[0] & 0x80) != 0;
length = header.Mid(1, 3).ToUInt();
overhead += length;
if (block_type == 4)
{
xiph_comment_data = metadata_header.Mid(4, (int)length);
has_xiph_comment = true;
comment_packet = ipacket;
}
else if (block_type > 5)
{
TagLibDebugger.Debug("Ogg.Flac.File.Scan() -- Unknown metadata block");
}
}
// End of metadata, now comes the datastream
stream_start = overhead;
stream_length = Length - stream_start;
scanned = true;
}
