override public IDataBlock DetectData(IDataReader dataReader, IDataBlockBuilder dataBlockBuilder, IScanContext context)
{
QtAtom root = new QtAtom(context.Detectors);
// Try to parse a contiguous block of headers
using (QtParser parser = new QtParser(new ByteStreamDataReader(dataReader)))
{
if (!parser.ParseRoot(root, dataReader.Length))
{
dataReader.Position = dataReader.Length;
return(null);
}
// Synchronize the position of the data reader
dataReader.Position = parser.Position;
}
// Trim trailing unknown or large unparsable atoms
QtAtom lastHeader = root.LastHeader;
long firstHeaderOffset = ((QtAtom)root.Children[0]).Offset;
while (lastHeader.IsUnknown && lastHeader.Parent != null)
{
if (lastHeader.RelativeEndOffset == ((QtAtom)lastHeader.Parent).RelativeEndOffset)
{
break; // Last child perfectly aligned with parent atom
}
lastHeader.Parent.RemoveChild(lastHeader);
lastHeader = root.LastHeader;
}
// Discard data blocks of only 1 atom
if ((dataReader.State == DataReaderState.Cancelled) ||
(root.Children.Count == 0) ||
((root.Children.Count == 1) && !root.FirstChild.HasChildren()))
{
// Rewind data reader
dataReader.Position = firstHeaderOffset + 1; // lastHeader.Offset + lastHeader.Length; // != lastHeader.RelativeEndOffset; !!!
return(null);
}
context.Results = root;
var codecStream = new CodecStream(dataReader, dataBlockBuilder, root);
long?rescanPosition = codecStream.CreateCodecStreams();
// TODO: check for (complete) mdat block (for IsFullFile)
// Note: For consistency, always report the name of the detector itself, not a specific data format!
//dataBlockBuilder.DataFormat = root.DataFormat;
dataBlockBuilder.IsFullFile = IsFullFile(root);
var firstChild = ((QtAtom)root.Children[0]);
dataBlockBuilder.StartOffset = firstChild.Offset;
var lastChild = ((QtAtom)root.GetLastDescendant());
var endOffset = (lastChild.Offset + lastChild.Length);
dataBlockBuilder.EndOffset = endOffset;
dataReader.Position = rescanPosition ?? endOffset;
// If the last atom is an 'mdat' atom that was truncated for rescan to its minimum size, truncate the actual result!
if ((rescanPosition == (lastChild.Offset + 8)) && (lastChild == root.FindChild(AtomName.MediaData)))
{
dataBlockBuilder.EndOffset = rescanPosition.Value;
}
return(dataBlockBuilder.Build());
}
private string GetCodecStreamName()
{
return(CodecStream.GetCodecStreamName(_track, _sampleDescription, _truncated));
}