/// <summary>Initializes a new instance of the <see cref="ID3v2Frame" /> class.</summary>
/// <param name="header">The header.</param>
/// <param name="reader">The reader.</param>
/// <exception cref="ArgumentNullException">Header.</exception>
/// <exception cref="NotSupportedException"></exception>
public ID3v2Frame(ID3v2Header header, DataFrameReader reader)
{
if (reader == null)
{
throw new ArgumentNullException("Reader");
}
m_Header = new ID3v2FrameHeader(header, reader);
// prepare content (has to be decoded, decrypted, decompressed, ...
m_Content = reader.Read(m_Header.HeaderSize, m_Header.ContentSize);
switch (header.Version)
{
case 2: /*nothing to do, raw plain content data*/ break;
case 3: ParseVersion3(reader); break;
case 4: ParseVersion4(reader); break;
default: throw new NotSupportedException(string.Format("ID3v2.{0} is not supported!", header.Version));
}
// copy raw data and remove from reader
m_Data = reader.GetBuffer(m_Header.HeaderSize + m_Header.ContentSize);
}
bool ParseVersion3(DataFrameReader reader)
{
if (!reader.EnsureBuffer(4))
{
return false;
}
// calc size
byte[] sizeBytes = reader.Read(0, 4);
int size = 0;
for (int i = 0; i < 4; i++)
{
size = (size << 8) | sizeBytes[i];
}
size += 4;
// get data
if (!reader.EnsureBuffer(size))
{
return false;
}
m_Data = reader.GetBuffer(size);
// get flags
m_Flags = ID3v2ExtendedHeaderFlags.FromID3v23(m_Data);
return true;
}
/// <summary>
/// Reads the header (check <see cref="State"/> before usage).
/// </summary>
/// <returns></returns>
public ID3v2Header ReadHeader(out byte[] tagData)
{
if (State != ID3v2ReaderState.ReadHeader)
{
throw new InvalidOperationException(string.Format("Cannot read header at state {0}", State));
}
var header = new ID3v2Header();
if (!header.Parse(m_Reader))
{
tagData = null;
return(null);
}
m_BodyBytes = header.BodySize;
if ((header.Flags & ID3v2HeaderFlags.Footer) != 0)
{
m_BodyBytes -= 10;
}
State++;
if (header.Version < 2)
{
tagData = null;
return(null);
}
tagData = m_Reader.GetBuffer(header.HeaderSize + header.BodySize);
var bodyData = tagData.GetRange(header.HeaderSize);
// need to unsync whole tag?
if ((header.Flags & ID3v2HeaderFlags.Unsynchronisation) != 0)
{
bodyData = ID3v2DeUnsync.Buffer(bodyData);
m_BodyBytes = bodyData.Length;
}
// update reader (use cached data)
m_Header = header;
m_Reader = new DataFrameReader(bodyData);
return(header);
}
bool ParseVersion4(DataFrameReader reader)
{
if (!reader.EnsureBuffer(4))
{
return false;
}
// calc size
int size = ID3v2DeUnsync.Int32(reader.Read(0, 4), 0);
// get data
if (!reader.EnsureBuffer(size))
{
return false;
}
m_Data = reader.GetBuffer(size);
// get flags
m_Flags = ID3v2ExtendedHeaderFlags.FromID3v24(m_Data);
return true;
}
/// <summary>
/// uses the <see cref="Search"/> class to find the next id3 / mp3 frame start at the buffer.
/// </summary>
/// <returns>Returns the search result.</returns>
Search FindFrame()
{
// initialize the search and run it at the buffer
var search = new Search();
while (true)
{
// fill the buffer
if (!m_Reader.EnsureBuffer(1024) && (m_Reader.Available < 4))
{
if (m_Reader.Available == 0)
{
return(null);
}
// end of stream
var buffer = m_Reader.GetBuffer(m_Reader.Available);
InvalidData(buffer);
return(null);
}
// run the search
{
if (m_Reader.Contains(search))
{
return(search);
}
// nothing found, enqueue invalid data...
var buffer = m_Reader.GetBuffer(m_Reader.Available - 2);
InvalidData(buffer);
// .. and start new search
search = new Search();
}
}
}
