/// <summary>
/// Creates a new empty frame.
/// </summary>
public MP3AudioFrame(byte[] data)
{
m_Data = data;
Header = new MP3AudioFrameHeader(data);
if (Header.Validation != MP3AudioFrameHeadervalidation.Valid)
{
throw new InvalidDataException();
}
var dataLength = Header.Length;
if (dataLength == 0 || data.Length != dataLength)
{
throw new InvalidDataException();
}
}
/// <summary>
/// Parses the specified stream to load all fields for this instance.
/// </summary>
/// <param name="reader">FrameReader to read from.</param>
public override bool Parse(DataFrameReader reader)
{
if (reader == null)
{
throw new ArgumentNullException("Reader");
}
if (!reader.EnsureBuffer(4))
{
return(false);
}
var headerData = reader.Read(0, 4);
Header = new MP3AudioFrameHeader(headerData);
if (Header.Validation != MP3AudioFrameHeadervalidation.Valid)
{
return(false);
}
var dataLength = Header.Length;
if (dataLength == 0)
{
return(false);
}
if (!reader.EnsureBuffer(dataLength))
{
return(false);
}
m_Data = reader.Read(0, dataLength);
// check next header
if (reader.EnsureBuffer(dataLength + 4))
{
var nextHeaderBuffer = reader.Read(dataLength, 4);
var next = new MP3AudioFrameHeader(nextHeaderBuffer);
if (next.Validation != MP3AudioFrameHeadervalidation.Valid)
{
if ((nextHeaderBuffer[0] == 'I') && (nextHeaderBuffer[1] == 'D') && (nextHeaderBuffer[2] == '3'))
{
// ID3 v2 tag incoming
}
else if ((nextHeaderBuffer[0] == 'T') && (nextHeaderBuffer[1] == 'A') && (nextHeaderBuffer[2] == 'G'))
{
// ID3 v1 tag incoming
}
else
{
// next header is invalid, check if the padding bit is set incorrectly
// there is a high pobability that the padding bit is invalid if
// the framestart is not directly after our buffer but one byte late
var newStart = dataLength + (Header.Padding ? -1 : 1);
nextHeaderBuffer = reader.Read(newStart, 4);
next = new MP3AudioFrameHeader(nextHeaderBuffer);
if (next.Validation == MP3AudioFrameHeadervalidation.Valid)
{
if (!Header.Padding)
{
// frame has a padding byte but the header padding bit is not set
m_Data = reader.Read(0, newStart);
}
else
{
// frame has no padding byte but the header padding bit is set
m_Data = reader.Read(0, newStart);
}
InvalidPaddingCorrected = true;
}
}
}
}
reader.Remove(m_Data.Length);
return(true);
}
