public static TagModel Deserialize([NotNull] Stream stream)
{
var frameModel = new TagModel();
frameModel.Header.Deserialize(stream); // load the ID3v2 header
if (frameModel.Header.Version != 3 & frameModel.Header.Version != 4)
{
throw new NotImplementedException("ID3v2 Version " + frameModel.Header.Version + " is not supported.");
}
var id3TagSize = frameModel.Header.TagSize;
MemoryStream memory = null;
try
{
if (frameModel.Header.Unsync)
{
memory = new MemoryStream();
id3TagSize -= Sync.Unsafe(stream, memory, id3TagSize);
stream = memory; // This is now the stream
if (id3TagSize <= 0)
{
throw new InvalidTagException("Data is missing after the header.");
}
}
uint rawSize;
// load the extended header
if (frameModel.Header.ExtendedHeader)
{
frameModel.ExtendedHeader.Deserialize(stream);
rawSize = id3TagSize - frameModel.ExtendedHeader.Size;
if (id3TagSize <= 0)
{
throw new InvalidTagException("Data is missing after the extended header.");
}
}
else
{
rawSize = id3TagSize;
}
// Read the frames
if (rawSize <= 0)
{
throw new InvalidTagException("No frames are present in the Tag, there must be at least one present.");
}
// Load the tag frames
uint index = 0;
var frameHelper = new FrameHelper(frameModel.Header);
// repeat while there is at least one complete frame available, 10 is the minimum size of a valid frame
// but what happens when there's only, say, 5 bytes of padding?
// we need to read a single byte to inspect for padding, then if not, read a whole tag.
while (index < rawSize)
{
var frameId = new byte[4];
stream.Read(frameId, 0, 1);
if (frameId[0] == 0)
{
// We reached the padding area between the frames and the end of the tag,
// signified by a zero byte where the frame name should be.
// we could double check we actually know what's going on
// and check the padding goes exactly to the end of the id3 tag
// but in fact it doesn't give us any benefit.
//
// one of the following cases must apply:
//
// 1) if the id3 tag specifies more bytes than the frames use up,
// and that space is exactly filled with zeros to the first audio frame,
// it complies with the standard and everything is happy.
//
// 2) if the id3 tag specifies more bytes than the frames use up,
// and that space isn't completely filled with zeros,
// we assume the software that generated the tag
// forgot to zero-fill it properly.
//
// 3) if the zero padding extends past the start of the id3 tag,
// we assume the audio payload starts with skippable stuff too.
//
// 4) if the audio payload doesn't start with a valid mpeg audio frame header,
// (VBR headers have valid mpeg audio frame headers)
// we assume there's a tag in a format we don't recognise.
// It still has to comply with the mpeg sync rules,
// so we will have to use that to find the start of the audio.
//
// in all cases, we read the specified length of the id3 tag
// and let the higher-level processing inspect the audio payload
// to decide what is audio, what is extra padding,
// and what is unrecognised (non-id3) tags.
// how much does the tag size say should be left?
frameModel.Header.PaddingSize = rawSize - index;
//// advance the stream past any zero bytes,
//// and verify the real measured size against that specified in the tag
//uint observed = SeekEndOfPadding(src) + 1;
//if( frameModel.Header.PaddingSize != observed )
// throw new InvalidPaddingException(observed, frameModel.Header.PaddingSize);
// advance the stream to the specified end of the tag
// this skips any non-zero rubbish in the padding without looking at it.
stream.Seek(frameModel.Header.PaddingSize - 1, SeekOrigin.Current);
break;
}
if (index + 10 > rawSize)
{
// 10 is the minimum size of a valid frame;
// we read one already, if less than 9 chars left it's an error.
throw new InvalidTagException("Tag is corrupt, must be formed of complete frames.");
}
// read another 3 chars
stream.Read(frameId, 1, 3);
index += 4; // have read 4 bytes
//TODO: Validate key valid ranges
using (var reader = new BinaryReader(stream, Encoding.UTF8, true))
{
var frameSize = Swap.UInt32(reader.ReadUInt32());
index += 4; // have read 4 bytes
// ID3v2.4 now has sync-safe sizes
if (frameModel.Header.Version == 4)
{
frameSize = Sync.Unsafe(frameSize);
}
// The size of the frame can't be larger than the available space
if (frameSize > rawSize - index)
{
throw new InvalidFrameException(
"A frame is corrupt, it can't be larger than the available space remaining.");
}
var flags = Swap.UInt16(reader.ReadUInt16());
index += 2; // read 2 bytes
var frameData = new byte[frameSize];
reader.Read(frameData, 0, (int)frameSize);
index += frameSize; // read more bytes
frameModel.Add(frameHelper.Build(Encoding.UTF8.GetString(frameId, 0, 4), flags, frameData));
}
}
return(frameModel);
}
finally
{
memory?.Close();
}
}
/// <summary>
/// Create a frame depending on the tag form its binary representation.
/// </summary>
/// <param name="frameId">type of frame</param>
/// <param name="flags">frame flags</param>
/// <param name="frame">binary frame</param>
/// <returns>Frame of tag type</returns>
public IFrame Build(string frameId, ushort options, byte[] frame)
{
// Build a frame
IFrame frameBase = FrameFactory.Build(frameId);
frameBase.Flags = options;
flagHandler.Flags = options;
uint index = 0;
uint size = (uint)frame.Length;
Stream stream = new MemoryStream(frame, false);
BinaryReader reader = new BinaryReader(stream);
if (flagHandler.Grouping == true)
{
//TODO: Implement grouping when watching grass grow stops beeing intresting.
/* The byte readed here is the group, we are skiping it for now*/
reader.ReadByte();
index++;
}
if (flagHandler.Compression == true)
{
switch (flagHandler.Version)
{
case 3:
{
size = Swap.UInt32(reader.ReadUInt32());
break;
}
case 4:
{
size = Swap.UInt32(Sync.UnsafeBigEndian(reader.ReadUInt32()));
break;
}
default:
{
throw new NotImplementedException("ID3v2 Version " + flagHandler.Version + " is not supported.");
}
}
index = 0;
stream = new InflaterInputStream(stream);
}
if (flagHandler.Encryption == true)
{
//TODO: Encryption
throw new NotImplementedException("Encryption is not implemented, consequently it is not supported.");
}
if (flagHandler.Unsynchronisation == true)
{
Stream memStream = new MemoryStream();
size = Sync.Unsafe(stream, memStream, size);
index = 0;
stream = memStream;
}
byte[] frameBuffer = new byte[size - index];
stream.Read(frameBuffer, 0, (int)(size - index));
frameBase.Parse(frameBuffer);
return(frameBase);
}
/// <summary>
/// Save the ID3v2 frames to a binary stream
/// </summary>
/// <param name="frameModel">Model keeping the ID3 Tag structure</param>
/// <param name="stream">Stream keeping the ID3 Tag</param>
public static void Serialize([NotNull] TagModel frameModel, [NotNull] Stream stream)
{
if (frameModel.Count <= 0)
{
throw new InvalidTagException("Can't serialize a ID3v2 tag without any frames, there must be at least one present.");
}
using (var memory = new MemoryStream())
using (var writer = new BinaryWriter(memory, Encoding.UTF8, true))
{
var frameHelper = new FrameHelper(frameModel.Header);
// Write the frames in binary format
foreach (var frame in frameModel)
{
//TODO: Do validations on tag name correctness
var frameId = new byte[4];
Encoding.UTF8.GetBytes(frame.FrameId, 0, 4, frameId, 0);
writer.Write(frameId); // Write the 4 byte text tag
var buffer = frameHelper.Make(frame, out var flags);
var frameSize = (uint)buffer.Length;
if (frameModel.Header.Version == 4)
{
frameSize = Sync.Safe(frameSize);
}
writer.Write(Swap.UInt32(frameSize));
writer.Write(Swap.UInt16(flags));
writer.Write(buffer);
}
var id3TagSize = (uint)memory.Position;
// Skip the header 10 bytes for now, we will come back and write the Header
// with the correct size once have the tag size + padding
stream.Seek(10, SeekOrigin.Begin);
// TODO: Add extended header handling
if (frameModel.Header.Unsync)
{
id3TagSize += Sync.Safe(memory, stream, id3TagSize);
}
else
{
memory.WriteTo(stream);
}
// update the TagSize stored in the tagModel
frameModel.Header.TagSize = id3TagSize;
// If padding + tag size is too big, shrink the padding (rather than throwing an exception)
frameModel.Header.PaddingSize =
Math.Min(frameModel.Header.PaddingSize, 0x10000000 - id3TagSize);
// next write the padding of zeros, if any
if (frameModel.Header.Padding)
{
for (var i = 0; i < frameModel.Header.PaddingSize; i++)
{
stream.WriteByte(0);
}
}
// next write the footer, if any
if (frameModel.Header.Footer)
{
frameModel.Header.SerializeFooter(stream);
}
// Now seek back to the start and write the header
var position = stream.Position;
stream.Seek(0, SeekOrigin.Begin);
frameModel.Header.Serialize(stream);
// reset position to the end of the tag
stream.Position = position;
}
}
/// <summary>
/// Build a binary data frame form the frame object.
/// </summary>
/// <param name="frameBase">ID3 Frame</param>
/// <returns>binary frame representation</returns>
public byte[] Make(IFrame frameBase)
{
flagHandler.Flags = frameBase.Flags;
byte[] frame = frameBase.Make();
MemoryStream memoryStream = new MemoryStream();
BinaryWriter writer = new BinaryWriter(memoryStream);
if (flagHandler.Grouping == true)
{
//TODO: Do grouping some place in the universe
byte _group = 0;
writer.Write(_group);
}
if (flagHandler.Compression == true)
{
switch (flagHandler.Version)
{
case 3:
{
writer.Write(Swap.Int32(frame.Length));
break;
}
case 4:
{
writer.Write(Sync.UnsafeBigEndian(Swap.UInt32((uint)frame.Length)));
break;
}
default:
{
throw new NotImplementedException("ID3v2 Version " + flagHandler.Version + " is not supported.");
}
}
byte[] buf = new byte[2048];
Deflater deflater = new Deflater(Deflater.BEST_COMPRESSION);
deflater.SetInput(frame, 0, frame.Length);
deflater.Finish();
while (!deflater.IsNeedingInput)
{
int len = deflater.Deflate(buf, 0, buf.Length);
if (len <= 0)
{
break;
}
memoryStream.Write(buf, 0, len);
}
if (!deflater.IsNeedingInput)
{
//TODO: Skip and remove invalid frames.
throw new InvalidFrameException("Can't decompress frame '" + frameBase.FrameId + "' missing data");
}
}
else
{
memoryStream.Write(frame, 0, frame.Length);
}
if (flagHandler.Encryption == true)
{
//TODO: Encryption
throw new NotImplementedException("Encryption is not implemented, consequently it is not supported.");
}
if (flagHandler.Unsynchronisation == true)
{
MemoryStream synchStream = new MemoryStream();
Sync.Unsafe(memoryStream, synchStream, (uint)memoryStream.Position);
memoryStream = synchStream;
}
return(memoryStream.ToArray());
}
