public Mpeg2SystemCarver(IMpeg2SystemReader reader, IResultParser <IMpeg2SystemReader> systemHeaderParser, IScanContext scanContext)
{
_reader = reader;
_systemHeaderParser = systemHeaderParser;
_scanContext = scanContext;
_state = reader.State;
_minHeaderCount = (uint)Mpeg2SystemDetector.Configurable[Mpeg2SystemDetector.ConfigurationKey.MinSystemHeaderCount];
}
public Mpeg2SystemReader(BitStreamDataReader dataReader, IMpeg2SystemState state, IReaderState readerState)
{
_dataReader = dataReader;
_state = state;
_readerState = readerState;
_maxZeroByteStuffingLength = (uint)Mpeg2SystemDetector.Configurable[Mpeg2SystemDetector.ConfigurationKey.MaxZeroByteStuffingLength];
_stuffingBytesResultFormatter = new StuffingBytesResultFormatter();
}
public void Parse(IMpeg2SystemReader reader, IResultNodeState resultState)
{
IMpeg2SystemState state = reader.State;
// Check start code and determine header-specific parsing strategy
state.StartCode = reader.GetBits(32, Attribute.StartCode, "{0:X8}");
ISystemHeaderParser headerParser;
if (!resultState.Valid || !_headerParsers.TryGetValue(state.StartCode, out headerParser))
{
resultState.Invalidate();
return;
}
// Invoke the header-specific parsing strategy
headerParser.Parse(reader, resultState);
if (!reader.Valid)
{
return;
}
// Handle stuffing (leading 00's before the next start code)
uint zeroByteStuffing = reader.GetZeroByteStuffing(Attribute.ZeroByteStuffing);
if (IsFragmentBreakPoint(state))
{
reader.BreakFragment();
return;
}
string headerName = resultState.Name as string;
// Record the header and (possible) the extension
if (state.LastHeaderName == null)
{
state.FirstHeaderName = headerName;
}
state.LastHeaderName = headerName;
state.LastHeaderZeroByteStuffing = zeroByteStuffing;
state.ParsedHeaderCount++;
}
private bool IsContinuousStream(IMpeg2SystemState state, ulong systemClockReference)
{
ulong lastSystemClockReference = state.LastSystemClockReference;
if (lastSystemClockReference == FirstSystemClockReference)
{
return(true);
}
// Compare system clock reference to last system clock reference.
// It should be higher and have a limited time gap.
if (systemClockReference < lastSystemClockReference)
{
return(false); // Indicates a discontinuity because of a backwards jump in time
}
ulong timeGap = (systemClockReference - lastSystemClockReference);
return(timeGap < ((state.IsMpeg2() ? 27E6 : 90E3) * _maxTimeGapSeconds));
}
private bool IsFragmentBreakPoint(IMpeg2SystemState state)
{
return(state.ParsedHeaderCount > _maxHeaderCount);
}
